The top three battery chemistries coming soon to EVs – and none of them are solid-state
Electric vehicles saw a subtle, but significant evolution in batteries during the 2010s.
For example, the BMW i3’s battery capacity doubled between 2013 and 2019, using the same physical size of cells.
However, nothing particularly exciting happened regarding the chemistry of those batteries.
They were almost always NMC – lithium nickel manganese cobalt oxide – with gradually decreasing cobalt content and improved energy density (in other words, how much range you can pack into a given weight or size of battery).
Now, we’re starting to see some seriously exciting battery developments on the horizon, all of which have important implications for EVs, and will result in a diversification of the chemistries offered in different makes and models of electric vehicles.
Here, we’ll look at my personal top three favourite battery chemistries that are due to hit EVs soon – and despite the hype, you may be surprised to learn that none of them are solid-state.
LITHIUM IRON PHOSPHATE AND LMFP
The first of my top three battery chemistries is already offered in some of the best selling EVs today, including the Standard Range Tesla Model 3 and Y, MG4 and BYD’s electric cars.
Lithium iron phosphate (LFP) replaces NMC in the cathode. It contains no cobalt or nickel, so is cheaper and more ethical, and on top of this, it has a longer cycle life (can be charged and discharged more times before its capacity degrades to the point that it’s no longer suitable for your needs) and doesn’t catch fire if severely damaged.
BYD’s Blade LFP cell doesn’t even get hot if drilled straight through when fully charged!
LFP’s range issue is on the cusp of being solved by LMFP, whereby manganese (or another metal) is added alongside the iron and phosphorus in the cathode.
This boosts the cell’s voltage without adding much cost, and brings the energy density of this cobalt-free, cheaper, safer and more ethical chemistry close to that of NMC.
Tesla was rumoured to be introducing LMFP in the refreshed Model 3, which would give the Standard Range model a range in excess of 300 miles per charge, but this has yet to happen. However, watch this space: in addition to the Tesla rumours, Gotion, a cell manufacturer backed by Volkswagen, plans to start manufacturing its LMFP cells this year.
SODIUM-ION
While there is a lot of focus on how make batteries that provide the most range for an electric vehicle, some of the most exciting developments will result in slightly less range vs today, but with huge advantages in other areas.
Sodium-ion is a prime example of this: it eliminates cobalt, nickel, copper and lithium, replacing them with cheaper and far more abundant materials with well-established supply chains. After all, sodium is found in sea salt.
Sodium-ion cells don’t pose a fire hazard if severely damaged; perform better than lithium-ion in freezing temperatures; don’t require as much thermal management (battery cooling/heating) as lithium-ion cells; and are much easier and safer to ship.
So, not only are they cheaper to make and manage, but they’re cheaper to transport too, which delivers a double cost saving to consumers. Their downside is that their energy density is less than LFP, so the range per charge of EVs equipped with the first generation of sodium-ion cells will arguably best suited to urban drivers, but that’s still a valid part of the market, and one that needs affordable cars.
WHAT ABOUT SOLID-STATE?
The term “solid-state” encompasses a broad church of different electrolytes and chemistries, rather than being a single type of cell.
“Solid-state” refers to the replacement of the liquid electrolyte and polymer separator with a solid electrolyte that does both jobs, ideally while offering faster charge and discharge times and improved safety.
This means that, for example, a solid-state electrolyte could be used with a silicon anode and an LMFP cathode.
The electrolyte may be so safe that the silicon anode would no longer be required, allowing for a pure lithium anode to be used instead and further reducing the bulkiness – and increasing the energy density – of the battery pack.
This means that some of our cheapest and most ethical chemistries today could be made so compact that they exceed the energy density of today’s more expensive market-leading NMC chemistries, while solid-state electrolytes used in conjunction with NMC cathodes could result in seriously impressive electric vehicle ranges, including “city cars” that are more than capable of taking on cross-country journeys with ease.
On top of this, some startups are now turning their attention to how to make solid-state electrolytes for sodium-ion cells.
This would further reduce the cost of batteries by allowing more abundant and ethical sodium to be used instead of lithium, in batteries that rival the range per charge of today’s EVs.
While early versions of solid-state batteries are already in use in niche applications today, it will be a few years before we see them offered in mass produced electric cars and vans.
One thing is for certain, though: electric vehicle battery chemistries are diversifying, and shall continue to do so, bringing many cost, range and ethics advantages which are great news for electric vehicles and their buyers.
https://electricdrives.tv/the-top-three-battery-chemistries-coming-soon-to-evs-and-none-of-them-are-solid-state/