The Future of the Electric Car Battery
The annual demand for battery storage is expected to increase 8-fold by 2030 (see Fig. 1.) This increase in demand for energy storage is partially driven by the need for batteries in ‘smoothing’ the power network, as we move to renewable but less reliable power sources. However, by far the biggest cause of this increase in demand is due to the expected rise of electric vehicles (EV’s.) For the last 30 years, the lithium-ion battery has dominated the energy storage industry. However, they have significant limitations and so there is a serious need for a new battery technology to allow the green revolution to occur.
Fig. 1: Annual lithium-ion battery demand
Lithium-ion batteries can be found in almost every portable electrical device you might own: mobile phones, laptops and electric cars. The advantages that Li-ion batteries bring in comparison to its predecessors, are a high energy density, low maintenance, minimal self-discharge, and ability to be recharged for many cycles before needing replacement. However, these advantages over predecessors are often now insufficient for current EV requirements. A median petrol car can go 420 miles on 1 tank of petrol, the weight of which is about 40kg. For only 75% of that range, the required battery weighs in at 625kg, so clearly the energy density is a long way off that of petrol cars. Furthermore, over the number of cycles an EV’s battery would undergo, battery degradation does begin to have an effect, seeing about a 10-15% reduction in capacity in 200,000 miles, at which point it needs to be discarded. It is noted this is improving with better battery manufacturing.
There are also several drawbacks to them, the first being safety. Li-ion batteries can overheat and are sensitive to high voltages which need careful protection systems, without which they can set fire. They also require a lot of natural minerals, such as cobalt and nickel, which are energy intensive to mine, finite natural resources and largely found in politically volatile regions such as Russia or the Democratic Republic of Congo. Cobalt free Li-ion batteries have shown promise however, which would take away some of the strain on its supply. Nickel will remain an issue and is highly likely to become the rate limiting factor in speed of Li-ion battery manufacture. Finally, these batteries are expensive. This point represents the biggest hurdle in bringing electric cars to the masses.
Fig. 2: Tesla on fire
Solid State Batteries
Solid-state batteries have for a long time been hailed as the battery that will replace the Lithium-ion. They are theoretically better in almost every way than a Li-ion battery. Crucially they have a much higher energy density, but on top of this they will charge faster, have longer lifetimes, and contain no flammable liquids as they use a solid electrolyte. The CEO of QuantumScape, one of the most hyped solid-state research companies who are partnered with Volkswagen, predicts it will start producing batteries for cars as early as 2024-25. This bold claim, as well as two small technological advancements have sent QuantumScapes’s market capitalisation as high $48B at the end of 2020 after going public through a SPAC merger. However, it now trades just under a third of that at $15B, with other companies potentially further ahead, such as Toyota hoping to unveil a prototype car fitted with a solid-state battery this year. Solid Power based in Colorado is also looking a strong contender, having produced a small multi-layer solid state battery too, and are teamed up with BMW and Ford.
Possibly the most interesting player in the battery game are the leading EV manufacturer, Tesla. They, nor Elon Musk, have so much as mentioned solid-state batteries, let alone start research on their own. Tesla has made significant advances in Li-ion battery technology, with improvements in lifespan, energy density and manufacturing scale. This does place Tesla exposed, and if the likes of Toyota, VW, and BMW crack solid-state batteries soon, Tesla’s competitive advantage of having the longest ranges is eliminated. I personally think with the very real chance that this does happen, Tesla being valued more than all the sum of all other car companies is bewildering.
There is a strong argument to say that solid-state batteries are still so far off overtaking a Lithium-ion battery that Tesla is correct in not focussing their efforts on them. Former senior battery engineer at Tesla, Gene Berdichevsky, recently said in a white paper that, ‘Solid state batteries are likely to be irrelevant to the revolution.’ He points to four technical reasons for that: formation of dendrites (small lithium spikes), physical failure due to stresses, defects within the electrolyte and manufacturing constraints. Berdichevsky also notes that it is very possible for Li-ion batteries to reach $50/kWh by the end of the decade (currently at $137/kWh.) This would be achieved through further improvements in chemistry and manufacturing of the battery packs, which would in turn improve the life span of the battery and critically make them recyclable.
We are still a long way off seeing solid-state batteries becoming a reality for commercial use in electric cars, and so Lithium-ion will continue to dominate for at least the next 10 years. Let's hope to be proven wrong. However, given the idea of a solid-state battery is not a new one, and the very high hurdles standing between their development right now and their practical usage in cars, I do not think we will be. One thing is for certain, and that is that battery technology today is not sufficient for the necessary green revolution to occur. With or without solid-states, battery technology will get better and get closer to the required performance needed. For now, I personally will be steering clear of gambling on companies like QuantumScape but do hope they and others continue to make great advancements in the field.