EV Battery Reference: Basics, Technologies, Care & Benefits.

Introduction.

What do I mean ‘Battery’? The origin of the name.

I use the term battery to mean something acts as storage of electrical energy, and although I rarely state ‘rechargeable battery’ I when I use the term ‘battery’, it can be taken to mean ‘rechargeable battery’.

The term ‘battery’ has evolved over time, and my interpretation is that mobile phones and electric vehicles have made rechargeable batteries so common that we no longer need bother saying ‘rechargeable’ depending on the context.

Historically, and before modern ‘batteries’ existed, the word ‘battery’ meant ‘a number of similar articles‘. The word being independent of what these articles are. The word ‘battery’ still can be used for a ‘battery of guns’ or a ‘battery of tests’ or batteries of other things in keeping with that original meaning. However, without the ‘of something’ the word ‘battery’ is usually one or more electrical cells for storage of electricity.

Originally the electrical ‘battery’ was always ‘battery of similar chemical cells’ because early applications always required a number of similar cells. This became shortened to ‘battery’ as ‘battery of cells’ is too long for frequent use, and now, even when there is only one cell such as a single ‘AAA’ cell, we still call it a battery.

In fact it is reported that the first use the term battery was not for a ‘battery of cells’, but was in 1749 for a ‘battery of electrical capacitors built by Benjamin Franklin, and it was that Volta introduced a ‘battery of chemical cells’ as we think of today, but these early electrical storage units were always called ‘batteries’ because you needed lots of similar components inside to create enough voltage. Now that we even call single cells ‘batteries’, which given that ‘battery’ originally meant ‘a number of similar articles‘, it is a little contradictory given the original meaning, and shows how meanings change.

The meaning of ‘battery’ is still evolving as now the word ‘rechargeable’ is often implied.

Some people feel it is only a battery if the energy is stored as one or more chemical ‘cells’, but I would argue that it does not matter how the electrical energy is stored, to most people it is battery because of the function, not how it achieves that function. So in general use, anything that holds energy for later use as electricity, could be considered a battery. So even a capacitor can be considered a battery, as was the case with Benjamin Franklin.

Chemical Energy: The power for all types of vehicle engines or motors in use.

All current vehicles are powered by chemical reactions, just not all convert the chemical energy into electricity. Internal combustion engines are powered by the heat from a chemical reaction between gasoline/petrol or diesel or hydrogen with oxygen, and electric vehicles are powered by electricity generated by a reaction between the chemicals inside the battery, or for hydrogen fuel cell vehicles, the chemical reaction between hydrogen and oxygen to produce electricity.

This is more fully explained here.

Single Use vs Rechargeable Batteries: For Vehicles, ‘battery’ implies ‘rechargeable’.

Depending on context, the term ‘battery’ can be assumed to either mean ‘single use battery’ or ‘rechargeable battery’. If someone asks, “do you have AA batteries?”, single use batteries are usually assumed unless it is specifically requested that the batteries are ‘rechargeable’. However, with mobile phones, automobiles and battery electric vehicles, battery is assumed to be ‘rechargeable’. We never say, ‘rechargeable car battery’, or ‘rechargeable mobile phone battery’ because these batteries are always assumed to be ‘rechargeable’ batteries.

In some respects, single use batteries are very similar to fossil fuels. Chemicals with stored chemical energy that are disposed of once the energy has been used. But this is about rechargeable batteries.

On this page, and all pages related to EVs, ‘battery’ is taken to mean ‘rechargeable battery’ unless specifically stated otherwise, as the future is hopefully one where portable power is by rechargeable batteries. In many ways, single use batteries would be like staying with gasoline as source of energy. With both gasoline and single use batteries, energy supplies are replenished by adding a new supply of the original chemicals. With (rechargeable) batteries, the battery is restored to the original state by putting energy back into the battery, and no new ingredients are required. The battery itself is ‘renewable’ rather than ‘replaceable’.

Recharging Vs Refuelling: Recharging is recycling whilst refuelling is replacing discarded spent fuel.

What Is The Difference?

All vehicles are powered by a chemical reaction, under the principle:

• When Ingredients ‘react’ the result is ‘waste’ plus energy.

With an internal combustion engine, the ‘waste’ from the ‘reaction’ is mostly CO2 and water vapour, which are disposed of through the exhaust. With an battery vehicle, the ‘reaction’ is inside the battery, and the waste remains inside the battery.

Recharging is using energy to convert the waste back to the ingredients.

Refuelling is disposing of the ‘waste’, and replacing the supply of ingredients.

Could You ‘Recharge’ A Gasoline Engine? Technically, Yes.

In a gasoline engine, the main chemical reaction is:

gasoline + oxygen → CO2 + Water + energy(heat)
2 C8H18 + 25 O2 → 16 CO2 + 18 H2O ( simplified as per Wikipedia)

While there are some ‘burnt impurities’, and the heat is so intense that some nitrogen is also burnt, the components listed above are those that are needed for the engine to work.

In theory, if the tailpipe emissions of CO₂ and water were retained, then instead of refuelling it would possible to add heat back into the ingredients, and thus run the equation in reverse, and thus ‘recharge’ back from ‘waste’ to ingredients:

CO2 + Water + energy -> gasoline(synthetic) + oxygen

This would result in a ‘sustainable’ internal combustion engine vehicle. Of course, there are some problems. This is not an easy reaction to run in reverse, and as internal combustion engines are very inefficient, so far more energy is required to reverse the reaction that the car was able to driving. All the heat energy will be needed to be ‘refuelled’ as well, even thought most of the heat from combustion was lost when driving. But if we captured the emissions from an internal combustion engine, then we could bring the car to an energy source and ‘recharge’ the emissions back into fuel and oxygen, thus operating like an inefficient electric vehicle.

This may sound far fetched, but the reaction:

CO₂ + Water + energy -> fuel + oxygen

Is called photosynthesis, and although the direct fuel, sugar, takes a few conversation steps to make biofuel, this is the exact principle of the process of making biofuel.

Of course, ‘recharging’ in this case is extremely slow slow, and have this car wait while the recharging takes is impractical. So instead, the ‘recharging’ to make biofuel from CO₂ water and energy is done outside the car, and the car is refuelled with biofuel made earlier. Or, in the case of fossil fuels, made way earlier.

Can You ‘Refuel‘ A Battery Electric Car? Yes, by battery swap.

Similarly, a lithium iron battery also runs a chemical reaction, only this is two half reactions at each side of the battery. Battery chemistries vary, but this is one example:

1)  LiCoO2 -> CoO2 + Li+ + e-(electrical energy)
2)  Li+ + 6C + e- -> LiC6

Where the Li⁺ electrolyte is in a solvent that can flow between cathode and anode. You will often see these formulas with a bi-directional arrow, because taking the electrical energy out makes the reaction go one way (discharge), but adding the electricity back makes the reaction goes the other way (recharge). At ‘recharge time’, instead of putting electrical energy back, it is technically possible to simply take out the CoO₂ (Cobalt dioxide) and LiC₆ (lithium graphite) as exhaust, refresh the electrolyte, and put in new LiCo₂ (lithium cobalt dioxide) and C (graphite), replacing the chemicals as we are doing when refuelling a gasoline car. By replacing the chemicals, the car would be ready to go again without the time delay of recharging.

The problem with replacing the chemicals, refuelling the car by refuelling the battery, is that for every battery chemistry, there are different chemicals, which would mean refuelling points would need to be range of ‘fuels’ even more diverse than the different octane ratings we have for gasoline/petrol. Plus, not all chemical ingredients are in the convenient liquid form.

The solution is the battery swap. This requires there is an interface between battery and car which is purely electrical, and independent of the chemicals within the batter. There are still problems, primarily standardising battery form factors so not every vehicle needs it own individual battery swap is a benefit on road trips when full refill off power is needed quickly, but not as appealing as charging at home at night during the more common use of cars when not on road trips.

Hydrogen Cars: Half Way Solution?

Hydrogen cars are the “refuel’ solution with recharging taking place outside the car. The benefit of hydrogen over ‘biofuels’ is that hydrogen can be used in a fuel cell to allow for more electric motors for propulsion. The negative is that hydrogen is a very light gas, which cannot be liquefied at normal temperatures, resulting in the need for high compression which consumes significant energy.

Refuelling is Unstainable Without Recharging at Some Point.

In the end, there are good reasons why no one is going to actually wait while ‘recharging’ a gasoline fuelled vehicle.

The entire system with gasoline was conceived at a time when the very concept of ‘renewable’ appeared unnecessary. The approach was to never worry about ‘recharging’ the ingredients, because the supply of those ingredients was assumed to be effectively infinite, and the ability of the Earth to absorb the ‘waste’ exhaust gases was also assumed to be infinite.

If we now buy into sustainability and the idea that the ability of the Earth to absorb waste is finite, then we need to ‘recharge’ the chemicals we extract energy from as a similar annual rate to our use of the energy, whether we use fossil fuels, biofuels, hydrogen, or lithium based battery chemical reactions.

Nor is anyone going to refill the chemicals of a battery for a battery car, as batteries are designed for the battery to operate as a sealed unit, although battery swap of the entire battery does have some applications.

The ‘battery’ approach is to ingredients and ‘waste’ within a container, such that it an be either used to produce energy in the form of electricity on demand, or store electrical energy when connected to a supply.

Batteries and EVs.

Batteries and Electric Car Basics.

These are two very worthwhile videos, and while I initially find the first more entertaining, both are worth watching.

Batteries and the Price of Electric Vehicles.

There was a time when computers less powerful than what is today a low-priced home computer filled rooms, cost millions of dollars and were something normal people imagined having at home. There was a time in the 1980s and early 1990s when mobile phones could cost $4,000 or $5,000 and normal people did not imagine ever owning one.

The bad news is it is not certain every aspect of EV electric vehicles is about to go through that type of price crash. But the batteries most likely will, just as significant savings will also accrue with new manufacturing techniques as scale increases.

When I first wrote this in 2021 EV, I estimated the battery to be around 50% of the cost of an EV, although of course this varies widely, with at that time some EVs lower priced than a home battery of the same capacity. Between 2021 and this update in 2023, a significant portion of EV batteries have from Li-ion ternary batteries to LFP batteries, which has had a significant impact on price per kWh.

Cleantechnica estimates that between 2008 and 2022, the price of Li-ion batteries has fallen by over 90%. During this time in the USA, the battery of choice has been the Li-ion ternary battery, while in China the LFP battery has very much taken over, which has made the fall in battery prices even more significant.

During the time since 2008, the energy capacity of batteries in EVs has approximately trebled, which has reduced the impact of falling battery prices on the cost of EVs, but has allowed EVs to move from ‘city cars’ to general purpose vehicles capable of replacing ICE vehicles. With the many different battery technologies being developed at this time, is seems almost certain that LFP will not be the last shirt to a new lower cost battery technology by 2030, and the trend shows how prices would fall even without a new technology.

As battery prices continue to fall, battery capacity could rise even further, but EVs already have a range that makes them practical vehicles, so there is now less need for the same multiple of increase as there was in the past.

Why so many cells to an EV battery?

As can be seen in the battery EV basics section above, EV batteries are made of battery cells. Lots of battery cells.

Consider for a moment a simple double AA size battery cell vs a triple AAA size of the of the same construction, such as an Eneloop. Both sizes have the same voltage but different mA hours, or milliamp hours. For any one cell, the volage is the same regardless of the size of the cell, which for Eneloop is nominally 1.2V, as dictated by battery chemistry, which for Eneloop is NiHM or “nickel metal hydride”. While the voltage remains the save for any cell size, the stored energy increases with cell size.

Multiply amp hours by voltage for energy so the capacity of the first-generation is Eneloop 1.9Ah x 1.2v = 2.28 for the AA and 0.75Ah x 1.2v = 0.9Wh for the AAA.

Connect battery cells in series to add the voltages(V), and in parallel to add the Amp hours(Ah). So, two AA batteries in series has 2.4v and in parallel has 3.8Ah, but whichever way, the energy is that of the two batteries added together. Some devices use 2 AAA batteries, where one AA with provide more power, because with two batteries in series, there can be double the voltage.

Although there are in 2023 1,000-volt architecture EVs, most EVs from previous years were designed around 400-volt architectures with around 400-volt batteries, as 400 volts is all older DC-chargers can deliver. To make an EV battery of just under 400 volts, 300 cells in series would give 360 volts, but 300 cells is only 684Wh of energy, with is too not enough energy for an EV. Instead of 300 individual cells, 300 blocks of 100 parallel-cells with 228 Ah energy per block, would be 360 volts and 68,400Wh or 68.4kWh.

That is 300×100=30,000 Eneloop cells, but it would make a battery with voltage and energy of a modern EV battery! Fortunately, Lithium batteries have a higher voltage per cell and normally more energy per cell than an AA battery. As explained in the video above by Lucid CEO Peter Rawlinson, the 17-18Wh cells in initial Lucid Air vehicles are clearly larger than AA batteries but these initial Lucid Air vehicles still have over 6,000 cells in their batteries!

Charging and discharging speeds: batteries determine not just range, but performance and more.

It is no coincidence that mobile phones have a quite similar range of time for fully charging their much smaller battery packs to EVs for rapid charging their much larger battery packs. This is because battery size has little impact on the total fastest speed charge time, or the total fastest discharge time.

Size can have some impact, as charging or discharging a battery produces heat, and it can be a greater challenge provide cooling to dissipate that heat with a larger battery. Provided the temperate can be kept in the ideal range of temperatures for charging, then charging/discharging the entire battery pack takes the same time as charging each individual battery cell.

An Eneloop battery charger like the BQ-CC50 pictured takes the same time to charge 1 cell, or 2 cells.

Want to charge 20 cells at the same time? Then just use 10 of these chargers. Not matter how many cells you need to charge, if you have enough electrical power and no problem with overheating, then any number can be charged in same time it takes to charge just one cell.

That is, provided you have enough electrical power. Charing that 30,000 cell battery from the “why so many cells” section would take 30,000 times more electrical power to charge. The Lucid Air can require over 250 kW of power from a rapid DC charger. The is over 100x the maximum amount of power available from a typical home power socket. If fact the specification says charging ca be at up to 300kW.

That is a lot of power flowing to the vehicle battery pack when charging, but consider, the rate of charge results from the size of the battery. Double the battery size, either by using twice as many cells, or by using bigger cells, and it will still be able to be fully charged in the same time, with the maximum kW used during charging also doubling. Significantly, this means a car with 2x the battery size, can charge in the same amount of time, but then travel 2x the distance because it has a 2x bigger battery. Ok, almost 2x the distance unless this 2x bigger capacity battery unless the battery pack weighs no more and doesn’t require the car to be larger to fit the battery.

Clearly, withe same battery technology, a 2x bigger battery will have a 2x higher maximum kW during charging.

The convers is also true: a 2x bigger battery will have a 2x higher maximum kW during discharging.

Discharging, is powering the motor(s). The Lucid Air has a maximum power of 596kW from the standard battery model, which requires a flow of 596kW flowing out of the battery. This is double the maximum 300kW of power flowing into the battery charging, but unlike charging, this would never be a continuous flow of power for a long period of time. If the 596kW was consumed continuously, the 112kWh battery would be flat in 10 minutes. Peak power figures for all cars are only every for very short bursts, or supercars would all run out of fuel within 20 minutes.

The key point is that both the peak power for charging, and the peak power for driving, are proportional to battery size.

These principles apply to all EVs, and the Lucid Air only an example because the video with information on the battery pack was used as an information source.

The battery of an EV is many ways the equivalent to the engine of combustion vehicles.

Consider that the battery determines the maximum possible engine power. Just as batteries have a maximum charging speed, they have a maximum discharging speed, which is the maximum possible vehicle power.

People often mistakenly think of the battery as like a really big and expensive equivalent to a fuel tank, and an electric motor as a smaller lighter lower cost powerful equivalent to the internal combustion engine.

I say “mistakenly”, because the battery is neither directly equivalent to the fuel tank nor to the internal combustion engine.

Battery is more a mix of both, with electric motors being additional components needed to enable the battery to complete the role of movement.

Yes, the electric motor can fit in carry-on luggage yet outperform huge complex internal combustion engines, but it is rate energy is supplied from the battery that is the main constraint on EV power.

Batteries vs Other Portable Power Sources(H₂, Gas, Petrol, Diesel)

Disadvantage: The Size, Weight and Range or Operating Time.

The size, weight and cost of a battery to provide the same total power is greater than a tank of fuel.

The advantages of batteries as pure efficient energy storage would win all the time, if it was not for their one Achilles heel: the size, weight and cost required to provide power for a long time.

However, as battery technologies improve, size, weight and cost reduce.

The video to the left explains the case against battery power as it stood at the date of the video. As I am updating this section in late 2021, there are already batteries with over 4x the energy density of those in the video, and energy density continues to improve, so size of this disadvantage decreases.

Given that the cost of the battery is in most cases soon offset by reduced running costs, the disadvantage becomes that only a battery of smaller size and/or weight is possible, reducing running time/range.

As mentioned in the video, the improved efficiency of electrical power can counter the disadvantage.

Advantages: Pure & Efficient Energy Storage.

Universal Fuel Source: Energy vs Chemical Power.

In theory you could make a ‘recharging system’ for an internal combustion engine as described above, but in practice, it will never happen.

When you are out of fuel for a diesel or gasoline engine, you need more of the exact chemicals the engine requires. You can’t just stumble upon gasoline or diesel fuel, and you can’t easily convert other things that are available into gasoline or diesel fuel.

Sunlight, wind, and even heat can be used to make electricity. Almost any form of energy can be converted into electricity and used to charge a battery. The source of the electricity has no impact on the design of the electric car. However, you can just use anything that will burn to power an internal combustion engine. Even the minor change from gasoline to diesel requires a significantly different engine. When gasoline supplies are disrupted, everything that depends on that specific liquid is disrupted.

Internal battery chemistry can change from car to car with no need to modify how electricity is supplied to the car. All of that battery technologies discussed below can be used with the exact same electric motors.

A battery vehicle can use any source for the energy. Not only is the mains electrical system that is normally used as the source of energy available at almost every dwelling in the developed world, but it is also possible to provide energy from solar or wind. Even in the most remote location, it is possible to generate electricity from natural sources without any need to locate specific chemicals. With enough time people could even hand crank a small amount of electricity. This allows for vehicles such as the Aptera, or the Lightyear One, that can travel normal commuter distances each day on a day’s solar energy alone.

Since batteries are recharged by energy, rather than the chemicals inside the battery that react to produce the energy when it is needed, how the battery stores energy can change, with no impact on refuelling. The reactions above are for ‘conventional’ lithium-cobalt-graphite batteries that have been used in most mobile phones and electric vehicles so far, but already different battery chemistries are being introduced, with phosphorous having already replaced cobalt in BYD batteries, and also being introduced by Panasonic.

Supply Security and Sovereignty.

Moving from requiring one specific chemical formulation for fuel, to requiring electrical energy, is moving depending on a very specify supply chain, to almost total flexibility.

A fossil fuelled engine can only be fuelled by fuel matching the specific chemical formulation for which it is designed. It becomes like the razors and blades business model, but where the car producers make the razors, and the fossil fuel industry makes the blades.

The consumer perspective is fuel prices, and the extent to which consumers end up funding some very questionable nations and some very rich companies, the national perspective security of supply.

Electricity is generic, and can be sourced from solar, or wind, or tidal forces, from hydro or from waves, as well as from any fossil fuel. Particularly with solar power, consumers can themselves take control of supply. Any of these sources, and more, can be used to produce electricity. If you have energy, you can produce electricity, while the gasoline or diesel required by an internal combustion engine can only be produced by an oil refinery, which in turn requires a specific far from universal resource. Oil rigs are as complex solar or wind farms, but instead of then using solar and wind resources that cannot be controlled by cartels, oils supplies depend not just on the equipment, but those who own the rights to supply.

Electricity grids can be very dependent on one way of generating of electricity, but while with fossil fuels there is only choice between nations that can produce oil, with electricity, not only can most countries produce much of their own electrical needs, but there are also so many ways or making electricity that they count not ever be controlled by one cartel.

When it comes to the energy to power cars, while cars that are powered by solar cells alone are not viable, the fact that cars spend over 90% of their time parked, enabled batteries charged by solar cells to play a major role in providing the energy for cars, and allows a percentage of consumers to control much of their own energy source, putting downward pressure on prices for everyone.

Many problems can disrupt the supply of fossil fuel, but the very nature of the electric grid means long term disruption of electrical supply to a wide area is far less likely, and there are even off the grid solutions.

Efficiency.

A typical car fuel tank holds between 50 (Toyota Corolla) and 90 litres (Mercedes GLS580 3 row SUV) which is between 13.21 and 23.77 US gallons. A Ford F150 pickup is available with 23 to 36 US gallons, or 90 to 136 litres. The energy density of gasoline is around 8.76 kWh/l so this means the capacity in litres, US gallons and kilowatt hours of tanks are as follows:

• 2021 Toyota Corolla: 50 litres, 13.21 gallons, 438 kWh
• 2021 Mercedes GLS580/ F150 base model: 90 litres, 23.77 US gallons, 788 kWh

Yet a Lucid Air, with a 115kWh battery pack can travel further on than the Toyota, Mercedes or F150.

There is further discussion on efficiency as it applies to cars in the topic “range”, but in typical applications, electric engines are at least 3x more efficient than combustion engines, resulting in more work done per unit of energy stored.

Safety.

You have probably heard of battery fires, the reason you hear is because battery vehicles are new, so it makes news, not because of the risk, which is low. It turns out if you store energy, then that energy could either explode or burn if not safely stored. In reality there are far more combustion engine fires every year per vehicle than electric battery fires, and the main reason fires and the potential for explosion with batteries is reduced, is the efficiency. As electric vehicles typically need 1/4 or even less, resulting in 1/4 of the problem. There is more to add to this topic.

Energy Density.

Units.

Energy can be expressed as joules (Watt seconds) or kilowatt hours. I kilowatt hour is 60(seconds)x60(minutes)x 1,000 watts = 3.6 MJ (3.6×10⁶ Joules).

There are two measures of energy density:

• by weight: Wh/kg or J/kg
• by volume: Wh/litre or J/m³

Both are important, and although technically energy density should be called “specific energy”, when discussing batteries, the “energy density” discussed is most often weight.

Remembering there is no way to use more than around 25% of the energy from gasoline, so it being included in the table is not “like for like”.

Comparison.

Energy Density: here is how it compares with some batteries.

• By Weight:
  • Gasoline: 13,138 Wh/kg (neutrium.net) (notes, great, but only only 25% accessible)
  • Innolith future battery : 1,000 Wh/kg (2024?).
  • Solid State: 450-500 Wh/kg (proposed July 2020)
  • NCA: 322 Wh/kg (Panasonic)
  • NMC: 230~250Wh/kg
  • LFP: 130~190Wh/kg
  • Nickel-metal hydride battery – 60 to 120 Wh/kg
  • Nickel-cadmium battery – 45 to 80 Wh/kg
  • Lead-acid battery – 30 to 50 Wh/kg
• By Volume:
  • Gasoline: 9,405 Wh/litre (varies with octane rating, I found 8.9kWh/litre when researching range)
  • 1,000-1,200 Wh/litre proposed for solid state (July 2020)
  • BYD Blade Battery LFP 448 Wh/L
  • ONE Aries LFP battery: 287 Wh/litre and Gemini Hybrid 470 Wh/litre.

My plan is to add by volume data as I find it.

On this basis, a EV battery would weight around 10x what the equivalent amount of gasoline, and an 80kWhr battery = 80kWhr ÷ 250 Wh/kg = 320kg.

Also a 250kwh/kg battery is over 50x heavier than an equivalent tank of gasoline. (50×250=12,500)

Future.

When it comes to the energy density of the graphene battery, the numbers will surely be going to impress all the tech-savvy persons. In comparison to the good old lithium-ion batteries, graphene batteries will have a much higher energy density. This is because lithium-ion batteries tend to store up to 180 Wh per kilogram; on the other hand, graphene batteries are capable of storing up to 1000 Wh per kilogram. Therefore, now you can have a higher energy density battery pack in the same size as any other battery.

Graphene Battery Energy Density: Jan 2021

The most touted battery claiming a specific energy of 1,000 Wh/kg is the Innolith battery, but I have not seen any recent updates.

Our Next Energy: This company demonstrated a Tesla model S with a range of over 750 miles. This would suggest a battery with double the energy density of Tesla batteries, and thus around 500 Wh/kg (450), but it is hard to separate from the hype. The company has secured investment from BMW, Bill Gates and Jeff Bezos.

Several batteries claim 500 Wh/kg. E.g:

• Amprius

Battery Theory.

Terminology: Cathode, Anode, Electrode etc..

A note on terminology as it can be confusing, particularly the terms ‘cathode’ and ‘anode’ when discussing rechargeable batteries. The cathode is the terminal from which current flows, and the anode is where the current arrives. Since currents flow in the opposite direction during use of battery power or ‘discharge’ than current flows during ‘recharge’, each physical part of a rechargeable battery swaps roles. So, the cathode during battery use or ‘discharge’, becomes the anode during recharge. This causes much confusion, and I have seen several videos and sites that get confused by this and think one side of the battery is always the ‘cathode’ and the other is always the ‘anode’, not realising that technically this labelling changes between charging and discharging. Also note. to make things even more confusing, electrons flow in the opposite direction to current. For these reasons, I will often use the less technical sounding, but clearer and unambiguous, ‘positive electrode’ and ‘negative electrode’.

State of Charge(SOC): How full is my battery?

Answer: There some guesswork in the answer unless the battery is fully charged or fully flat. Don’t rely on what happens at other levels as being precisely reproduceable.

With a fuel tank, either optical sensors or a ‘float’ can be used to measure how full the tank is, but you can’t count the electrons in a battery. There can be inaccuracy in measuring the depth of fuel in the tank, but it is measurable. A human could read that depth with a stick. But just as human cannot read with certainty the amount of energy that a battery has stored and can provide, or its current ‘state of charge’, nor can any electronic state of charge system.

You can measure battery voltage, but as can be seen from the data below, battery voltage readings only provide limited accuracy in determining state of charge. From charge cycle to charge cycle, the same voltage can occur at different levels of charge as the battery changes over time, and even with changes to internal temperatures in individual cells of the in the battery, and there are a lot of cells.

Another approach is to measure how much charge has been used since the battery was last fully charged, and then subtract charge used from the battery capacity to determine how much charge remains. This relies upon a precise value for battery capacity, the losses during discharge being predictable, and the losses between driving times also being predictable. Again, this is also imperfect, and inaccuracies can accrue any time the battery has been partially charged.

So how can any State of Charge system determine the level of charge in a battery?

• Answer: algorithms ‘using guesswork’ based on a combination of voltage and tracking energy added against energy consumed since the battery was last fully charged.

The only two times charge level can be known with certainty, is when the battery is full and stops taking more charge, and when it is empty and provides no more charge. In between full and empty, software looks at the record of how much energy has been used since the battery was full, subtracts that from full capacity, compares the answer with battery voltage and reports the conclusion as the answer.

So, when your phone says the battery is now 50% full, that may be a guess and not the real amount of charge. Which is why people report events like: “my phone battery just dropped 20% in two minutes!”. What actually happens in cases like this, is the state of charge system now has a revised guess on the state of charge in the battery, often as a result of battery voltage.

No, the battery did not lose, for example, 20% in 1 minute. Software just realised its previous guess was wrong on the basis of battery voltage or change in battery voltage.

It is useful to be wary of EV tests that measure figures like “how far this EV can travel after the range indicates 0 km”. Such tests are normally based to two false assumptions:

• The state of charge detection system for an EV is always able to accurately detect the actual state of charge: False
• Any over-reporting of state of charge measured at one time can be relied upon on other occasions: False.

Most batteries lose some voltage as they lose charge, following a ‘discharge curve’, and knowing the charge curve allows updates to calculations. Unfortunately, the voltage also changes for other reasons, such as temperature and load, making working form voltage alone a problem, plus the discharge curve of a battery changes over time. Getting readings of voltage under various conditions can allow periodic corrections of the guess, which is why indicated battery level can suddenly jump.

As can be seen from the graph here of the NMC discharge curve over time, a voltage of 3.5volts could represent very different states of charge throughout the life of the battery.

Another problem is that reading battery voltage draws some power, and the voltage seen will depend on how much power is being drawn from the battery at the time. Accelerating an EV rapidly, and drawing lots of power, will cause voltage to drop temporarily. So, voltage is not a perfect indicator.

Plus, the ideal battery would have the same voltage from almost full charged to fully empty, which makes reading voltage really challenging. The challenge of determining charge level varies with battery type, and in practice, the worse the battery type behaves, the easier the guessing gets.

Note, the curves shown here are all at constant temperature, and with constant power drain on the battery. In the real world of a car being driven, the load on the battery will also change the voltage as will temperature changes, putting ‘wobbles’ onto the readings.

As can be seen, from the graphs, LFP batteries have much flatter charge/discharge curves, which makes correcting calculations or ‘guesses’ harder.

For this reason, most car makers recommend periodically fully charging LFP batteries in order to allow software to provide a reference for the state of charge detection system to better determine level of charge. This is because as change in voltage is far less helpful in determining state of charge, the state of charge system is more reliant of measuring power used since the most recent fully charged event.

With both LFP and ternary batteries, the battery management system needs to maintain the data required to know the current charge curve and discharge curve of the individual battery.

Updating charge and discharge curves.

Whenever a battery discharges from full capacity, it can allow updating the discharge curve, and when the battery charges from a known and low state of charge, it can allow updating the charge curve, and these two curves being up to date allow for more accurate indications of state of charge.

Charge Time vs ‘Refuel’ time.

Chemical batteries are limited in the speed they can absorb charge, but recharge points are also limited in the speed they can supply charge. Fuel tanks for gasoline and diesel vehicles can absorb fuel ‘instantly’, but the practical limits of hoses that carry fuel, and pumps, means it still takes some time to refuel.

For comparison consider diesel vehicles. There are special ‘high flow’ pumps for large trucks that can deliver fuel so fast that the fuel will go everywhere instead on just into the tank if these ‘high flow’ pumps are used with vehicles not specially designed. The tank can take fuel ‘instantly’, but the hose from the fuel filler to the tank can only manage a certain speed. Trucks can use a really big hose to handle a higher speed, but that is also limited by the maximum rate the fuel pump hose can handle. So there are three constraints:

1. Gas/diesel pump speed.
2. Hose from fuel filler point on car/truck to tank.
3. Tank maximum fill speed (no problem with gasoline or diesel tanks)

With electrical vehicles, chemical batteries normally do have an effective limit on how fast ‘the tank can be filled’, but the other two limitations also apply:

1. Charging Station maximum power rating.
2. Car/truck connector and cabling to battery maximum power rating.
3. Battery maximum ‘fill’ (recharge) speed.

This means that even with future battery technologies that do not limit battery recharge speed, refilling will still not be instant, just as refilling a large truck today is not instant. Currently the fastest chargers have a maximum power rating 350kw, so a 100kw/hr battery would need 100/350 hours or 17 minutes to recharge. The Hyundai Ioniq 5, one of the fastest charging vehicles of 2021, can recharge 75% of an 77.4kw/hr battery in 18 minutes, so just over half the maximum possible.

Actual battery charging rates are determined by battery technology in use. See below for battery charging rates for lithium ion batteries, the type of battery used in all EVs today(2021).

Battery charging times will, by 2025 if not earlier, be able to rival times for filling liquid fuelled vehicles, but practical limitations of getting the power to the car may mean infrastructure to deliver that power at the required rate will be rare.

The reality is that battery swapping is the true equivalent of refuelling, and recharging is a very different concept to refuelling.

Although rapid recharging can even soon match refuelling time, rapid charging should be considered something to avoid. It requires special infrastructure, and even if lower cost than fossil fuels, is inherently expensive compared to recharging while parked. Private cars spend 95% of their time parked, so it should be only very on rare occasions that rapid charging is needed.

Battery Lifetime: Why do batteries ‘wear out’?

Batteries have a finite life, which is expressed in charge cycles.

It is important to understand that a ‘charge cycle’ is a number of cycles from fully charged, to flat, and back to fully charged. There can be a misunderstanding that even a half discharge and recharge will be using one cycle, but this is NOT true. If this was true, then half-discharge would be best avoided, but in fact the opposite is true, as the two half cycles will typically result in less battery deterioration than one full cycle.

A way to think of battery lifetime in an EV, is multiply the official range* per full charge by the number of full battery cycles, and this calculation should be the total distance the battery should survive.

Or it would be, if battery degradation was only the result of cycles, but rating batteries in cycles assumes “typical” cycles. In practice controlling temperature and limiting current during the cycles plays a significant role, and avoiding both ends of a full cycle by completing only partial cycles can extend battery life.

How to maximise battery lifetime and get the most battery cycles is under battery care, below.

*Note that although official range numbers are not the highway range number that people normally want, for this battery life calculation, the range on a test cycle is usually the best number. So, a vehicle with a range of 480km (300 miles) with a battery rated for 1,000 cycles, should be able to travel 480,000 km (300,000 miles) before the specified battery degradation level is reached. If that battery is always ‘half charged’ from 30% to 80% and thus half-charged 2,000 times, the battery life should be slightly higher.

Li Ion (Lithium Ion): The batteries of today (1998-2022?).

Overview.

At the time of writing, basically all EVs in the 21st century have had lithium ion batteries.

Despite first being developed back 1970, mass manufacture of any of the different types of lithium ion batteries is relatively recent. The first commercial battery products did not appear until 1991. If you are old enough to recall older mobile phones had first nickel cadmium batteries (invented in 1899), and then nickel metal hydride batteries, with both of these older battery types having a ‘memory effect’.

Recharging Lithium Ion Batteries.

Charge Rates.

Every battery has a maximum power that it can supply when proving power, and a maximum power it can absorb when charging. Generally speaking, the main focus is on the maximum power absorbed during recharge, as there are many situations where it is desired to charge the battery at the maximum possible rate, and few where it is desired to discharge at the maximum rate. Any car that can discharge its batteries in just 10 minutes is either attempting some form of speed record, or simply does not have enough battery life. The challenge is recharge speeds.

Batteries can now handle all the recharge speed we need. For example, CATL recently announced their Qilin batteries, to be mass produced now from December 2022, can be charged from 10% to 80% in 10 minutes, and stated they have future batteries that will be able to be charged from 10% to 80% in 5 minutes.

Now the question is how long will it take to have recharge stations that can charge batteries that fast.

The Lithium Iron Charging Curve, and the 10% to 80% (or similar).

Three are two ways that charging speed is indicated:

• A maximum charging speed.
• Charging time between a lower and upper limit.

While the maximum charging speed does reveal an upper limit to charging speed, this speed may never, or vary rarely, achieved. This is because the maximum charge rate for a battery varies according to how charged the battery is at that time, as well as the battery temperature.

Most batteries will accept charge 5x faster or more, at around 50% of full charge, than they will at 95% of full charge.

Charging only up to the point where charging slows, is advisable for both battery life in the long term, and fastest charging when on road trips.

Charging speeds and pack size: when all else is equal, a bigger pack add range faster.

Those speeds announced for 2023 represent a breakthrough, and in 2022, the fastest time for 10% to 80% is close to 20 minutes, and many typically cars will take around 40 minutes. Note that this percentage recharge time is per individual cell. With good batteries design, any number of cells can all be charged in parallel as this same speed, so no matter how large the battery, the same, or almost the same, total charging time can still apply. This means a larger battery with more cells not only provides more driving range, it can also store energy at a faster rate. Consider a car with a 50kWh “Kirin” battery, with an consumption rate of 100 w/km at 60km/h. This car can travel 350 km at 60 km/h using the charge available between 10% and 80% of that battery, and recharge the energy consumed in 10 minutes. Now consider a car with a 100kWh “Kirin” battery and the same rate of consumption. This second car will only drop the battery level from an initial 80% down to 45%, and could in theory possibly then recharge from 45% to 80% in just 5 minutes. The time to provide charge for the same distance halved, without any other change beyond increasing battery capacity.

Cobalt Lithium Ion: Since 1970 (NCA, NMC)

“Ternary Batteries”.

Electric vehicles so far have mostly used lithium ion cobalt oxide ion batteries (LiCoO₂) as described here and first developed in the 1970s. NCA batteries use Aluminium in place of the Manganese used in MMC batteries, but both also use Nickel and Cobalt in addition to lithium. Lithium is highly reactive which would make significant amounts of pure lithium dangerous, so cobalt is combined with lithium to form LiCoO₂ as a container to hold the lithium more safely in a less chemically active form. Cobalt is not rare, but cobalt in the form that is lowest cost to extract is found almost exclusively in the Congo, creating a supply chain risks, and at times as much of 10% of that Cobalt being mined, has been mined using unsafe practices. In batteries with cobalt, the cobalt becomes the main factor in the cost of the battery.

Note that with ternary batteries, limiting charging to 80% for normal use, as discussed in “battery care” is recommended.

NCA: LiNiCoAlO₂, Lithium Nickel Cobalt Aluminium Oxide Batteries.

The ternary chemistry used by Tesla and produced by Panasonic. Historically the highest density lithium battery, but also the battery presenting the greatest risk of fire.

NMC:  LiNi_xMn_yCo_zO₂, Lithium Nickel Manganese Cobalt Oxide Batteries.

The most popular batteries for EVs until 2021 for all but Tesla, and still most popular outside China in 2022. The fire risk, and energy density, is just slightly below that of NCA batteries.

LFP (Phosphorous): Popular in passenger EVs since 2020.

Lithium-ion phosphate batteries (LiFePO4 or ‘LFP’ for short) are an alternative to ternary batteries, which use cobalt, and LFP batteries feature reduced battery cost and result in a safer battery, with significantly lower fire risk. LFP batteries also outlast ternary batteries and in 2022 became the preferred battery for EVs.

Historically, despite being less expensive and longer life, lithium-ion phosphate batteries (LiFePO₄) have had lower energy density than cobalt-based batteries, which limited their use to busses and larger vehicles. However, several companies now have solutions to the energy density, which allows a price, safety and lifespan breakthrough from lithium phosphate batteries such as the BYD blade battery. LFP batteries may take over from the current, at the time of writing in 2021, champions: NCA and NMC.

As of 2021, LFP batteries are used almost exclusively in BYD vehicles, and to some extent in other Chinese brands and some Teslas. Teslas with LFP batteries do not have the “set limit 90%” option present with their NCA batteries. See battery care below for more details.

LFP batteries have a much flatter discharge curve than ternary batteries, which makes their state of charge more difficult determine, but can enable a much flatter charging curve, with the higher voltage at low state level of charge resulting in less current required, and better charging on 50kW or other lower current chargers.

LMFP: Lithium manganese Iron Phosphate (2024?).

Adding manganese, which is very low cost, reduces the amount of lithium required, and so reduces battery cost while at the same time increasing cell voltage and thus increasing density. They have been lifecycle limitation in the past with LMFP, however these are reported to have been solved.

Chinese media is reporting that CATL will mass produce lithium manganese iron phosphate (LMFP or LFMP) batteries already this year, on track with the company’s roadmap.

Adding manganese to the popular LFP formula increases the voltage and energy density of the battery cells, without a noticeable cost increase, since manganese is particularly cheap. However, I’m curious to see the impact of the voltage increase on the cycle life.

CATL will soon mass produce LMFP batteries

CATL’s LMFP goals

• Gravimetric energy density: 210-230 Wh/kg
• Volumetric energy density: 450-500 Wh/L

Considering a GCTP (gravimetric cell to pack) ratio of 90 % and a VCTP (volume cell to pack) ratio of 72 % of a module-less CTP battery, at the pack level we can reach 207 Wh/kg and 360 Wh/L.

It seems that most viable improvements to the energy density of the LFP chemistry will be made either by adding silicon to the anode or manganese to the cathode.

Anyway, some battery cell makers such as BYD, Gotion High-Tech, Sunwoda and Eve Energy are also testing LMFP batteries and providing sample units to automakers.

With LFP, LMFP, LNMO and sodium-ion we are starting to have plenty of cobalt-free battery chemistries to power the electric transportation revolution.

CATL will soon mass produce LMFP batteries

Links:

• https://cnevpost.com/2022/07/12/catl-said-to-mass-produce-lithium-manganese-iron-phosphate-batteries-within-this-year/
• https://www.takomabattery.com/lmfp-industry-special-report-in-2022/
• CATL LMFP batteries, 20% more autonomy by adding manganese to the LFP formula
• Raw materials: Lithium Manganese Iron Phosphate (LiMn_xFe_1-xPO₄) LMFP Cathode Powder, 500g

Lithium Carbon (Not for EVs).

So far too small for EVs, and instead best for mopeds and scooters.

• 2022 Aug: Lithium Carbon Battery From Allotrope Energy Can Recharge In 90 Seconds

Battery Technology Alternatives: Beyond Lithium Iron

(this section updated as new data emerges)

The benefit of all batteries being charged by electricity and output electricity, is that how batteries work internally can be changed with no impact on the infrastructure to recharge. This means that what we have now is only a starting point, and there are many potential improvements to charging times, cost, lifespan, safety and environmental impact still to come.

If you had a million dollars to invest in a battery company, right like right now where would you put your money, right, like it’s changing so quickly and every six months there is a new technology it doesn’t quite make it to market but you know it threatens to kind of like you know change the whole industry again, um so battery technology is a really weird one, right, like we have these lithium cells so they’re pretty good um five years from now they’re going to be way better different chemistry 10 years from now something different again so we are trying to be king of battery agonistic.

Aptera CTO Nathan Armstrong.

Sodium. 2023.

The press release from CATL, the worlds largest battery supplier for EVs:

Based on a series of innovations in the chemistry system, CATL’s first generation of sodium-ion batteries has the advantages of high-energy density, fast-charging capability, excellent thermal stability, great low-temperature performance and high-integration efficiency, among others.

The energy density of CATL’s sodium-ion battery cell can achieve up to 160Wh/kg, and the battery can charge in 15 minutes to 80% SOC at room temperature.

Moreover, in a low-temperature environment of -20°C, the sodium-ion battery has a capacity retention rate of more than 90%, and its system integration efficiency can reach more than 80%.

The sodium-ion batteries’ thermal stability exceeds the national safety requirements for traction batteries. The first generation of sodium-ion batteries can be used in various transportation electrification scenarios, especially in regions with extremely low temperatures, where its outstanding advantages become obvious. Also, it can be flexibly adapted to the application needs of all scenarios in the energy storage field.

The next generation of sodium-ion batteries’ energy density development target is to exceed 200Wh/kg.

At the event, Dr. Qisen Huang, deputy dean of the CATL Research Institute, said that sodium-ion battery manufacturing is perfectly compatible with the lithium-ion battery production equipment and processes, and the production lines can be rapidly switched to achieve a high-production capacity.

As of now, CATL has started its industrial deployment of sodium-ion batteries, and plans to form a basic industrial chain by 2023. CATL invites upstream suppliers and downstream customers, as well as research institutions to jointly accelerate the promotion and development of sodium-ion batteries.

CATL via PushEvs.

Advantages: (from clean technica)

• No dependence or use of cobalt, lithium, copper, or graphite.
• Patented zero-volt safe transport and storage.
• Low cost with the total cost of ownership compared with lead-acid batteries with the potential for more cost reductions.
• Uses existing lithium-ion manufacturing infrastructure which makes it scalable. Also, the company noted that it’s already been proven with several of its commercial manufacturing partners.
• Its energy density is also on par with lithium-ion phosphate and has a wider operating temperature range of -30℃ to +60℃.
• It also has fast charge and discharge capabilities.

Graphene: Future (September 2023?).

Although originally observed in electron microscopes in 1962 as occurring on supportive metal surfaces, graphene isolated and fully analysed for the first time in 2004 by Andre Geim and Konstantin Novoselov at the University of Manchester. This resulted in a Nobel Prize just 6 years later in 2010. Remember it took 16 years from Albert Einstein’s ‘miracle year’ of discoveries in 1905 to his Nobel prize in 1921, so it is clear this work was quickly recognised as a big deal.

Graphene based batteries hold promises of ‘instant charging’ combined with:

The rapid charging isn’t the only selling point. In the lab, NanoGraf says its graphene batteries show a 50 percent increase in run time compared to conventional lithium-ion ones, a 25 percent drop in carbon footprint, and half of weight needed to provide the same output.

Futurism.com

To date, graphene is the strongest mineral ever discovered, with 40 times the strength of diamond. It is more effective as a conductor of heat and electricity than graphite. … Graphene is capable of transferring electricity 140 times faster than lithium, while being 100 times lighter than aluminium. This means it could increase the power density of a standard Li-ion battery by 45%.

Mining Technology.

GAC, a subsidiary of Chinese state owned GAIC, has announced “The batteries will be installed in the first vehicle from September[2021]”, which would be the 1 year anniversary of the joint venture project for GAC.

Solid State Batteries: Future (VW plans for 2024-2025)

Introduction

Solid state batteries promise far higher energy density than current electrolyte lithium ion batteries, almost instant recharging, lower costs, and can be extremely durable. Some project it will take 10 years for them to take over, but a joint venture between VW group and QuantumScape plans for volume production by 2024-2025, a similar time from to Solid Power. Independent engineering analysis by Cleanerwatt and Matt Ferrel (undecided) do believe these timeframes. CATL, Panasonic/Toyota BYD all have too much at risk and too much engineering not to also be there if solid state does reach market by that time.

QuantumScape is developing what many consider the Holy Grail of electric car batteries: a highly-efficient, long-lasting, long-range, fast-charging electric car battery cell.

The battery startup achieves this by replacing* the liquid electrolyte that regulates the flow of current with a solid electrolyte.

The polymer separator used in conventional lithium-ion batteries is substituted with a solid-state ceramic separator, QuantumScape says. As a result, the less-efficient carbon or carbon-silicon anode is replaced with an anode of pure metallic lithium.

Forbes: Feb 2021.

Silicon Anodes: A Lithium battery upgrade: 2024.

Another proposed advance is the use of silicon anodes (positive terminal) to improve energy density.

Silicon anodes are famous for their energy density, which is 10 times greater than the graphite anodes most often used in today’s commercial lithium ion batteries. On the other hand, silicon anodes are infamous for how they expand and contract as the battery charges and discharges, and for how they degrade with liquid electrolytes. These challenges have kept all-silicon anodes out of commercial lithium ion batteries despite the tantalizing energy density. The new work published in Science provides a promising path forward for all-silicon-anodes, thanks to the right electrolyte.

A New Solid-state Battery Surprises the Researchers Who Created It

Links

• https://cleantechnica.com/2022/03/16/solid-state-battery-news-from-samsung-sdi-sakuu/
• Battery material supplier Sila promotes silicon anode material to battery makers. (2022-May).

Aluminium ion and Graphene: Future (Coin cells 2021, Automotive 2024-2025).

Batteries do not have to use lithium as the electron donor metal. Lithium is the lightest metal, and with the smallest size atom, but lithium atoms only have a single outer shell electron per atom, and thus only allow a +1 charge. Aluminium, although a larger and heavier atom, has 3 outer shell electrons, not one, and this gives aluminium the potential for a +3 charge, which it turns out can result in even greater energy density than with lithium. Plus lithium is so reactive, the batteries are normally made from lithium compounds, rather than lithium metal.

There are a variety of projects to deliver aluminium batteries, eg:

Graphenemg: Aluminium/Graphene batteries which can charge 20 to 60 times faster than lithium ion batteries.

GMG plans to bring graphene aluminum-ion coin cells to market late this year or early next year, with automotive pouch cells planned to roll out in early 2024.

Based on breakthrough technology from the University of Queensland’s (UQ) Australian Institute for Bioengineering and Nanotechnology, the battery cells use nanotechnology to insert aluminum atoms inside tiny perforations in graphene planes.

The GMG technology drops aluminum atoms into perforations in graphene.
The Graphene Manufacturing Group’s aluminum-ion technology can charge an iPhone in less than 10 … [+] GRAPHENE MANUFACTURING GROUP

Testing by peer-reviewed specialist publication Advanced Functional Materials publication concluded the cells had “outstanding high-rate performance (149 mAh g−1 at 5 A g−1), surpassing all previously reported AIB cathode materials”.

Forbes: 2021 May 15 (worth reading the article)

Supercapacitors and Ultracapacitors. (nothing scheduled to replace batteries).

Capacitors could also be used as the ultimate ‘solid state’ battery, simply storing a charge using electrostatic attraction. Although there is significant work on supercapacitors for use in EVs, and supercapacitors do function in some ways like a battery, the role they are currently ‘auditioning for’ is to augment the ability of a battery a battery to deliver extremely high currents instantly. If instead of feeding motors directly from a battery, the battery feeds a capacitor that in turn feeds power to the motor, then the system can deliver brief periods of peak current beyond what the battery can deliver. This role, not of being the primary battery, is what is being proposed at this time.

Companies involved include SkeletonTech.

Sulphur (2024 at earliest?)

German battery startup Theion is promising a new sulfur battery technology that could help mainstream electric cars offer 900 miles of range on a single charge. The best part? Compared to li-ion tech, sulfur is cheap.

New Sulfur Battery Promises 300% More EV Range

Lithium Metal (No date for commercial product)

This is a variation on the lithium ion batter as:

Lithium metal is one of the best candidates to replace graphite as an anode (positive terminal) material thanks to its high theoretical capacity. The problem is that batteries using lithium metal anodes currently have poor cycle life.

However, thanks to a new non-flammable dual-anion ionic liquid electrolyte this could soon change.

Push Evs 25th August, 2021

Sion Batteries.

Lithium Oxygen / Lithium Air (2025?).

Lithium oxygen batteries can also be described as lithium air batteries because the necessary oxygen can be found in the ai. Although air is mostly nitrogen, the strong bonding of the N2 molecules makes air look like mostly oxygen from the perspectrive of potential chemical reactions.

The lithium–air battery (Li–air) is a metal–air electrochemical cell or battery chemistry that uses oxidation of lithium at the anode and reduction of oxygen at the cathode to induce a current flow.^[1]

Pairing lithium and ambient oxygen can theoretically lead to electrochemical cells with the highest possible specific energy. Indeed, the theoretical specific energy of a non-aqueous Li–air battery, in the charged state with Li₂O₂ product and excluding the oxygen mass, is ~40.1 MJ/kg = 11.14 kWh/kg of lithium. This is comparable to the theoretical specific energy of gasoline, ~46.8 MJ/kg.

Wikipedia

There is potential for batteries with good energy density, but cost and reliability are the issues to overcome.

In early 2023, the announcements have been for a 1,200 kWh/kg battery with 1,000 cycle lifetimes, but without production dates or costs. Even at a high price, a battery with these specifications would be viable for aviation. There are no dates for commercialisation at this time, so 2025 is an optimistic guess at this time.

Announcements:

• 2023 February:
  • Cleantechnica: New Design For Lithium-Air Battery Could Offer Much Longer Driving Range
  • PV Magazine: Lithium-air battery with solid electrolyte
  • Sabine
• 2021 Science daily: Significant progress in lithium-air battery development
• 2018 Science: Energy density boost

Al Air. (No products scheduled to replace rechargeable batteries)

In addition to Aluminium ion batteries where aluminium replaces the lithium, there are also aluminium air batteries. However, these batteries are, so far, not rechargeable and thus not a contender in the same way as other batteries technologies discussed here.

EV Battery Lifetime, Care and Management.

Beware of misleading estimates of how long do EV batteries last based on past history.

One often-given simplistic answer is “10-20 years which is longer than the life of the car”. See video to the right.

A few problems with that answer:

1. The first being that on average cars last more like 20 years, so if that is true it could mean two replacements within a normal vehicle lifetime.
2. This data is taken from vehicles different from EVs today.
3. The data alone gives little indication of whether a vehicle can expect 10, 20 or even 30 years of operation without a new battery, and that difference really matters.

ICE vehicles on average manage a 20-year lifespan, and other than particularly high use vehicles such as taxis etc, most can manage this on their original engine, so 10-20 years is not really enough.

The good news is that there are many EVs available today with batteries that can be expected able to last over 2 million km (1.6 million miles), but the bad news is that there are also batteries that may last a small fraction of that driving distance.

While how many years it will t This can be sake to travel far enough to wear out a battery will vary according to how far the owner drives per year, any modern EV with around 400 km (250 miles) of range will easily exceed 20 years without needing to be replaced, particularly if the battery is LFP, while PHEVs or hybrids may have much shorter battery life.

The first step is to consider what can be learnt the 10-to-20-year battery life of early EVs, and then consider whether newer vehicles should expect longer or shorter battery life.

Most quoted data on battery life from real world experience, has to draw primality from old Nissan Leaf and Renault Zoe vehicles, and to a lesser extent from older Tesla Model S vehicles, as up until around 2017, these vehicles were the most popular EVs. The original Nissan Leaf vehicles from 2010 had a 24kWh LMO battery, with a 30kW battery only arriving in 2016, and the Zoe had a 22kWh battery until 2016, while original the Tesla Model S had a 60kWh NCA battery.

When all else is equal, a battery of half the size will last only half the time, so it makes sense the Leaf batteries may only last 10 years and the Tesla Model S batteries last 20 years. In fact, when looking at all the factors determining battery lifetime, it seems unlikely a Leaf/Zoe battery would last half the number of years of Tesla Model S battery.

Determining Battery lifetime: Range x Cycles.

Why does battery size affect battery lifetime? Because the life of a battery is calculated as a number of “cycles”, where a cycle is from fully charged to flat and then back to fully recharged. On average, a vehicle will travel its rated range on one full cycle. Yes, the rated range is often an overestimate of highway range, but the rated range is typically very appropriate for typical driving conditions, which is what is needed for this calculation.

For an approximate answer to battery lifetime: range x cycles for the type of battery.

Note that other factors including how the battery is maintained also play a role.

So, looking back at the historical battery life data, 1,000 cycles of the 24kWh Nissan Leaf battery, even for later versions with a range of 135km, would be only 135,000 km (84,000 miles), while 1,000 cycles of the lowest range original Tesla Model S 60 with a range of 335km (208 miles) would represent 335,00km or 208,000 miles.

The number of cycles a battery lasts also varies with battery chemistry with LMO batteries rated at 500-1,000 cycles and NCA batteries are rated at 500-1,500 cycles, suggesting probably more cycles for the NCA battery type.

Battery construction is another factor impacting the number of cycles a battery will last, but determining the impact of each construction type and each implementation of each construction type is very difficult.

Next, battery temperature management has a significant impact on battery life. The Nissan Leaf had ineffective battery temperature management, which further limits battery life. While the original Tesla Model S did not have a heat pump to ensure not only protection against over temperature but also under temperature, all Teslas now do have heat pumps as do BYDs and other major EV brands.

The last element in battery protection is to reduce occurrence of charging beyond the limits for optimum battery life, as decribed below under “battery care” and “keeping charge within a window“.

In summary, all these factors play a role:

• Range, which determines distance travelled per battery cycle.
• Battery chemistry: which determines the potential number of battery-cycles.
• Battery constructions: which helps achieves maximum potential cycles
• Battery thermal management: which limits degradation per cycle.
• Charging limits and lower charging speeds which also limits degradation.

Why EV batteries can many times longer than phone batteries.

Phone batteries seem to last as little as 5 years and are mostly Li-ion batteries which are rated at between 400-1,200 cycles, in the smaller form factor that fits within a phone. Note again, that a cycle is from fully charged to completely flat and back to fully charged, so a battery that discharges to 50% each day and is charged each night is experiencing 1/2 of a full cycle per day, which means or around 180 full cycles per year, so 5 years would be around 900 cycles.

Then main reason the typical EV battery will last many years longer than a phone battery, is that a normal day will be a smaller percentage of the battery cycle, with a typical EV having a range of 400 kms and the typical daily driving distance of between 30 to 60 km (20 to 40 miles) per day depending on country, which means only one cycle per week, instead of 3.5 cycles per week being more typical for a phone.

Then adjust for the fact that more effort goes into construction and thermal management, and a higher level of adoption of charging limiting, and you get to 20 years instead of around 5 years.

The problem for Hybrid and other small battery EVs: Much shorter battery life.

Now consider the appeal of the plug-in hybrid, or EV designed for commuting only: instead of “lugging” around a heavy battery that could last an entire week in the city, why not a less expensive lighter battery that will still be sufficient for just over one full day? Or in the case of a plug-in hybrid, a why not only battery that is only sufficient for a typical day, given there is the “back-up” of an Internal Combustion Engine for any occasion when the battery is not enough?

One problem with these smaller batteries, is that these batteries could experience a full cycle every 1 or 2 days, resulting in battery life similar to that of a mobile phone of around 5 years, or if there is a full cycle every day, even just half the life of the battery of a mobile phone!

Which brings us to hybrids without the plug, where the battery is very, very small, and is only charged using energy that originated from the fuel tank. These very small batteries could even experience multiple full battery cycles within a single day.

Small batteries do cost less initially, but if they need to be replaced many times, the final cost could be higher due to the extra expense of replacements.

Battery Replacements?

Batteries can be replaced, as shown on this video. While the battery structure with dedicated EVs is often currently integrated into the vehicle, and the replacement is specific to the vehicle, the process is simpler than replacing an engine in an internal combustion engine vehicle, which mean 3rd party EV battery replacement should be easier an engine replacement with an ICE vehicle.

On one hand, batteries are improving performance including lifespan so rapidly that already we are seeing batteries that may outlast the normal life of a motor vehicle and never need replacement. But on the other hand, it could become desirable to replace original batteries non only due to faults or problems before their full lifespan, but because rapidly improving battery technology makes a battery upgrade highly desirable.

And as I said before, with batteries, it looks they’re going to start lasting way longer than the vehicles, which means you can amortize the cost of the battery over three vehicle lifetimes right, so where there were its going to land on batteries right now like no one has any idea. It’s really a strange time to be in this industry. And with the mineral resource issues and mining stories coming out about lithium extraction, your going to see more attention being put to battery technology. I think were going to see some interesting alternatives coming out here pretty quickly. Especially on the solid state side of things, you’re going to see some interesting breakthroughs.

Aptera CTO Nathan Armstrong.

The off the cuff remarks quoted above convey the contradiction that while batteries may now last longer than the car, they may be the first part of the car to be out of date. Fortunately, replacing the batteries can be practical, and as batteries improve, replacing them can result in a vehicle that becomes even better than when new. When batteries are replaced, the materials are valuable, and recycling is possible.

General battery care principles.

Battery Life and Battery Charging.

Current Li Ion batteries, and most likely all future chemical batteries, can deteriorate over time as noted under ‘battery life’.

Batteries are rated for a number of ‘charge cycles’, and as explained above, it is important to understand that this is a number of cycles from fully charged, to flat, and back to fully charged. There can be a misunderstanding that even and half discharge and recharge will be using one cycle, but this is NOT true, and in fact the opposite is true, as the two half cycles will typically result in less battery deterioration that one full cycle.

Partial cycles are exactly that: only a part of one cycle.

Maximum battery life will result if the battery cycles are never experienced by the battery as complete ‘full to flat’ cycles.

Optimum battery life results when the following principles are all adhered to:

1. Recharge and discharge currents must be limited to avoid causing elevated batteries temperatures.
2. Rapid charging is best used sparingly.
3. Batteries should rarely be discharged until capacity is exhausted.
4. Batteries should rarely be charged to full capacity.

See the guidance specifically on ternary batteries (NCA, NM etc as most EVs as of 2022) or LFP batteries, but overall principles here apply to most modern rechargeable batteries also apply with mobile phones.

With mobile phones, most of us break rule 4 almost every day by leaving our phones on charge overnight. Now phones can have software designed to maximise battery life, and detect a charge is an overnight charge so they can:

• Use a slow charge provided there is sufficient time.
• Pause the charge as soon as a ‘during the night’ level is reached.
• Resume the charge as late as possible in the morning to ensure the phone is ready for the start of the next day, topped up to a level which still leaves a safety buffer.

For specific guidance on EV battery care, see the section on ‘

But we not yet at the point where software can be fully aware of when to fully charge, and when to limit charging below the maximum.

Charging outside the schedule of overnight charging can assume special circumstances and rapidly charge and allow rapid charging to proceed to full charge if the phone is left on charge.

There are articles that suggest rapid charging has no significant impact on battery life, but full analysis always reveals that the increase temperatures that result from increased current do reduce battery life, and the only question is as to whether the convenience justifies the impact. There is no doubt rapid charging is useful, the main care requirement is to limit rapid charging to when it is needed. With a relatively low-cost mobile phone battery in phone that will be obsolete in perhaps 3 years, it matters far less than with a high-cost EV battery in vehicle that still has value as a used vehicle many years after initial purchase. The average age of a car, even in the US, is around 12 years, and overall vehicle lifetime is typically around 20 years.

Some phones (e.g. Apple) do have software to try to avoid bad charging practices, but this is nowhere near as important with a phone as with a car.

Keeping charge within a window.

As discussed above in ‘battery life‘, EV batteries gradually deteriorate. However, battery life can be extended by following guidelines and those for the relevant battery type. Some steps battery care steps do not so much care for the battery itself directly, but for the battery management system and its ability to detect state of charge. Of course, caring for the battery, and charging at the correct speed for the state of charge.

Why bother?

Mobile phone batteries have similar chemistry to EV batteries (typically these are ternary batteries with cobalt), and we don’t limit their charging to 80%, so why bother with EV batteries? The two main reasons are:

• EV batteries represent a much bigger investment than a phone battery does.
• Cars have a longer life than mobile phones, so EV batteries need to last longer.

If we paid thousands of dollars for our mobile phone battery, and expected it to last at least 10 years, then we would look after it far more.

Ternary batteries: Lithium-Ion Batteries.

Note that these batteries require systems limiting charging speed as the state of charge approaches around 80% when the optimum rate of charge is often significantly lower and should only be charged above 90% on rare occasions. Long term storage should ideally be at 50%. Here is an article on the impact of different charging patterns, but note this data only applies to “ternary” Nickel/Cobalt batteries, which at the time of writing in 2021 are almost the only batteries in some markets, but it won’t stay that way.

LFP Batteries.

LFP battery cells use a lower voltage around 85% of that of ternary battery cells, and as the battery voltage plays a role in battery degradation and a fully charged LFP battery has a lower cell voltage, the requirement to limit charging of LFP cells is far less significant. Further, an LFP battery has around 3x the maximum life as a ternary battery, so even if treated with less caution, should still last longer. However, some argue that to get that full 3x extra life, LFP batteries should be treated just as carefully, while others argue the same chemical properties that result in LFP being a significantly lower fire risk, also means there is significantly less degradation when fully charged.

Typically keeping the battery between about 50% and 80% will result in maximum battery life, but without periodically fully charging the battery, the reported state of charge will become too inaccurate to ensure the battery is being kept between desired limits.

While avoiding fully charging very often is optimal for battery life, doing so can create problems for the state of charge % (SOC) system with an LFP battery. Without periodic fully charging, the SOC % of battery life the car thinks it has, can drift further and further from reality.

On balance, best to fully charge more LFP often than with ternary batteries, but still not all the time. How often to fully charge depends on how much trust needs be put in the state of charge. Manufacturers will normally recommend practices that ensure the battery will safely outlive the warranty requirements and yet still keep SOC systems quite accurate. A common usage pattern is that an EV may require an accurate SOC system only when on those typically quite occasional ‘road trips’. Between those road trips, often much less range is required, and allowing SOC system to become quire inaccurate no real problem. In this case, charging to 100% far less than recommended by the manufacturer could prolong battery life, and will be practical provided any road trip, or any other time charge could fall to a low level, is proceeded by fully charging.

Then there is the need of the SOC system to also periodically observe low level of charge. to Around once every 10x typical range, not the lower highway range, the battery should have state of charge dropped to the lower voltage part of the charging curve that occurs at around 15% state of charge, in order to allow the battery management system to ‘observe’ the lower part of the charging curve and enable an update of the stored data for charging curve and discharge curve. This is not needed sufficiently often as to impct battery life.

Battery Makers.

Car Brands.

So far, only BYD from China makes their own battery cells. Even Tesla, who makes battery packs from battery cells from Panasonic and CATL, does not yet make their own batteries. This may change, particularly with major brands would would see a huge part of their revenue go to battery suppliers.

VW.

Are VW looking at following in the footsteps of BYD?

• 2022 July 7: VW Investing $20 Billion into Battery Cell Plants
  • Also reported by Bloomberg, Electrek and Autoweek.

With initial capacity of 40 GW, no, there are not on the road to being a BYD. Well, not yet.

Market Shares.

2202 H2.

2022 H1.

• SNE Research: Chinese companies lead the global electric vehicle battery market in the first half of the year
• Tesla supplier CATL commands 34.8% of the battery market in 1H22

Global EV Battery Shipment – January-May 2021:

If we take a look at the year-to-date numbers, it turns out that CATL (22.1 GWh) maintained its first place, but it’s only 0.4 GWh ahead of LG Energy Solution (2.7 GWh). The combined market share of those two manufacturers is 53.7%, which means that every second xEV on the planet is equipped with CATL or LGES batteries.

CATL clearly benefits from very high sales in China (including LFP deal with Tesla) and several global  contracts, while LG Energy Solution got a boost from the deal with Tesla in China and massive expansion globally.

Inside EVs May 2021

Panasonic, with 13 GWh, is not only behind the leaders, but its growth rate is below 74%, which is a worrying sign. Market Shares are as of May 2021.

1. CATL – 22.1 GWh (up 300%) with 27.1% share.
2. LG Chem’s LG Energy Solution – 21.7 GWh (up 184%) with 26.6% share
3. Panasonic – 13.0 GWh (up 74%) with 16.0% share
4. BYD – 5.5 GWh (up 235%)
5. Samsung SDI – 4.6 GWh (up 106%)
6. SK Innovation – 3.8 GWh (up 154%)
7. CALB – 2.5 GWh (up 418%)
8. Envision AESC – 1.6 GWh (up 11%)
9. Guoxuan – 1.4 GWh (up 336%)
10. PEVE – 1.0 GWh (up 43%)
    other – 4.3 GWh (up 235%)
    Total – 81.6 GWh (up 169%)

CATL: The worlds largest battery maker.

CATL is moving further ahead of rivals, particularly with the Qilin battery, available in LFP and ternary batteries, and supplies both to Tesla.

• 2022-07-14 New Super-Fast Charging Technology Can Charge a Battery to 80% in Five Minutes
  • CATL will launch a 10 C-rate EV battery
• 2022-07-13 CATL says it’s developing M3P battery, different from LMFP battery.
  • This is a new way of using manganese to make a longer range LFP battery
• 2022-06-23 CATL launches CTP 3.0 battery “Qilin,” achieves the highest integration level in the world
  • CATL launches CTP 3.0 battery
  • mass production early 2023, also features 10 minutes 10-80% recharge rate
  • it can deliver 13% more power than the 4680 battery, accomplishing an all-round improvement in range, fast-charging, safety, service life, efficiency and low-temperature performance.
  • For more pages, see PushEVs,

LG Chem: Battling some challenges.

LG chem is limited by having had problems with battery fires with both the Chevrolet Bolt and Hyundai Kona, plus not having an LFP battery as of 2022.

Panasonic: The Initial supplier to Tesla.

• 2022 July Panasonic Reports Robust EV Battery Demand In Q2 2022

Panasonic were for a long time Tesla’s only battery partner, however Tesla ramping up in China has seen a closer relationship with CATL, plus Panasonic does not yet offer LFP batteries as of 2022.

BYD: The Blade battery.

BYD is the only battery maker that is also a car maker. BYD has gone stronger than anyone with LFP, with the their blade battery largely regarded as the safest battery on the market as of 2019-2022.

Note that BYD LFP batteries have effective charge rates that are close maintaining their peak charge rate: How does BYD make the blade battery charge faster than the ternary lithium battery

• Sept 5: BYD overtakes LG Energy Solution to become world’s No. 2 battery maker in July

GAC

• 2022 July 04: GAC introduced its new-generation LFP battery
• 2022 April 9: GAC unveils battery technology with range of over 1,000 km

Prologium.

Supplier to Vinfast and Mercedes, with upcoming solid state batteries.

• 2022 July 10: Solid-State Battery Race Just Got Hotter With New VinFast-ProLogium Mashup

Gotion High Tech (VW)

• 2022 July EV battery maker Gotion raises $685 million in Swiss GDR offering

S Volt (solid State)

• SVolt Energy Readies Solid-State Battery With 400 Wh/Kg Energy Density For Production

Upcoming Products.

Under battery technologies below, there are several new products and their proposed timelines. However, this is not car companies announcing products. I will add links here to cars with new tech, but it may take time:

Tesla 4680 Battery.

WeLion: NIO expected to get small batch of 150-kWh semi-solid-state batteries from WeLion in September

Conclusion.

The battery journey is still at an early stage. Right now, the cost of batteries puts EVs at a cost disadvantage to conventional cars, but that disadvantage is evaporating rapidly as shown by the quite competitive F150 lightning recently announced. By 2025, there will be a cost competitive EV for almost all new vehicle market segments.

However, 2025 is not the end of the line. EVs will continue getting less expensive for years to come, just as PCs did for decades.

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Updates.

• 2023 May 19 th: Revised EVs and Batteries section and explained how batteries determine EV power.
• 2023 March 2 nd : Lithium air batteries and updates to EV battery pricing and EV battery lifetime and battery care.
• 2022 Sept 7: BYD as now no2 battery maker.
• 2022 Aug 14: Added Video on GMG graphene Al batteries, LMFP, and general updates.
• 2022 July 21: Added State of charge: How full is my battery?
• 2022 July 14 : Updated information on new battery technology from CATL, and GAC, plus VW launches battery division.
• 2022 July 9: Added more information on leading battery makers.

Articles found after posting.

• Exploring Massless Energy Battery Breakthrough 20th July 2021.
• Solid State Batteries – Autumn 2021 mass production in Japan. Is it FINALLY happening? 18th July 2021.
• Toyota’s NEW Batteries will Make EVs CHEAP 18th July 2021.
• Tesla 4680
  • Tesla’s new Game-Changer 4680 Battery already on Production will Crushing EV competitors 18th July 2021.
  • Game Over! Tesla’s 4680 Battery Causes Big Manufacturing Fights 19th July 2021.
• Why This Battery Breakthrough Could Make EVs Cheaper 30 June 2021.

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