Solid State Batteries: Are we there yet? | Autocar Professional


If electric cars have to deliver the future we all expect them to, there will need to be several advances made in the coming years. The first, of course, involves the greening of battery components; specifically the mining and production of lithium. Automotive battery production currently releases around half a dozen tonnes of CO2. Up next safety; which is still a huge problem, especially thermal runaway. This is even more critical in hot countries like our own. And finally there’s performance, packaging and cost, advances we all expect electric cars to make in the coming years.

What’s fascinating is that all three issues can potentially be resolved, partially at least, if solid state battery technology rolls over the horizon in the coming years. Expected to make landfall or mass manufacture and widespread adoption somewhere between 2027 and the end of the decade, solid state batteries are both currently leaden with potential and at the same time fraught with technological hurdles.

Solid state; what’s the difference?

But what exactly is a solid state battery? It’s actually quite simple. Lithium-ion batteries we use in cars use a liquid electrolyte to help transfer electrons from one side of the battery to the other. Remember electrolysis? Yeah, something like that. And since the electrolyte is in liquid form, this makes the battery large, heavy and sensitive to thermal runaway. This is why, in comparison to a conventional lithium-ion battery, solid-state battery technology has the potential to increase energy density, reduce charge time, and make it more stable when it comes to thermal runaway.

Solid state batteries however are expensive. Currently costing up to three times more, pound for pound, they however make up for it as they also can hold three times the charge and deliver thrice the range. How far will EVs with solid state batteries be able to go? Toyota says that by the year 2027, its EVs will be able to travel around 1,400km on a single charge. And unlike today, because of better thermal management, solid state batteries won’t have to stick to the 80 percent limit when it comes to DC fast charging.

Hurdle after hurdle

So much for the potential. There however are also myriad hurdles. For one, several battery makers around the world are struggling to overcome the problems of cracks forming in the solid separator. Some battery makers are suffering lower than expected energy densities (measured in W-h/kg), and then to make these new tech batteries viable, costs need to be reduced significantly. Also part of the equation, even improving conventional lithium-ion batteries.

Still, progress has been made and many companies around the world, especially in Japan, Korea and China are currently moving into the production feasibility phase. While this phase is also sure to throw up its fair share of issues, what’s clear is that progress is being made and we are moving forward, slowly but steadily.

Also on the cards, and often touted as a solution, are sodium-ion batteries. This type could remove the difficult to mine Lithium from the equation. Sodium ion batteries currently however don’t have the density required to be used in cars and currently are only thought to be suitable for use in static applications where weight and size aren’t issues.

Another way we could see faster adoption of solid state tech is if companies like Toyota introduce them in hybrids first. This would potentially resolve some of the problems and then progress once the technology is more widespread would serve only to accelerate the production and use of large capacity units.

But plenty of allied advantages too

Apart from its fundamental strengths, solid state batteries will also offer advances in other areas, many not conventionally associated with the battery. One of the most important is that solid state batteries will be much flatter in general and that means they will be great for packaging. How much of a reduction in size are we talking about? Toyota says the size will go down from roughly 150mm today to approximately 100mm eventually, and that’s huge in packaging terms. So solid state batteries will allow engineers to build lower slung, more aerodynamically efficient cars and with their lighter weight it would also make the design of two door sportscars more feasible. Most sporting EVs today have four doors for a reason, and that reason of course is the size of the battery and its weight. You can bet your last Yen Lexus’ sporty FT-Se show at the Tokyo Salon earlier this year will use a solid state battery. How else can it achieve that roofline?  

Leading the charge

So who’s ahead in the race to bring solid state batteries to the market? Surprisingly Toyota, and it’s simply because it holds the most patents on the tech. What’s just as important, Toyota has recently even tied up with Idemitsu, currently placed third, for the manufacture of solid state batteries. So is Toyota’s solid state battery all but ready? Panasonic, Samsung and LG, the other big Japanese and Korean battery makers are also close on its heels, with some holding onto advantages in specific areas.

Also equally important, Chinese battery giants CATL and BYD who have been ‘showing’ plenty of progress in recent years, especially in their projections. Don’t write off these state sponsored and supported world leaders in battery production, remember they can work their way around most patents anyway.

Way forward

Solid state batteries when they arrive will be game changers. Various chemistries are being researched for suitablility in EVs. Their compact proportions, high performance and ability to blend into any design will fundamentally change how we engineer and manufacture cars. Imagine, when they arrive on the scene en masse, born EV platforms will have to evolve or be rendered outdated.  Keep your eye on this potentially disruptive emerging technology, it has the potential to fundamentally change the game.


This article was first published in Autocar Professional’s December 15, 2023 issue.


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