What is a solid-state battery?

Remember the good old days? Your engine would start to turn a little slow when it was cold and you’d think to yourself, ‘time for a new battery’.

You’d almost certainly ignore that early warning, though, and continue to let the battery wind its way down to certain death and then require a roadside assistance rescue. Or a long walk to the parts store. Invariably, though, the exercise was as simple as forking out for a like replacement.

It doesn’t quite work that way anymore, and the old starter battery is only one part of the equation. Even though a pure EV still has a starter battery you’re familiar with.

Let’s take a simple look at what constitutes a solid-state battery; something that is very much the way of the future.

In short, the key difference between a solid-state battery and a traditional lithium-ion battery is what the ions pass through. A solid-state battery uses solid electrodes and a solid electrolyte, rather than liquid or polymer gel electrolytes. In effect, then, it is exactly what it’s called – a solid-state battery.

Solid-state batteries are an important next-step for electric vehicles, key technology towards faster charging times, extended battery life, improved safety, as well as providing longer driving range for EVs.

Other claimed benefits include increased energy density, which would allow batteries to be smaller and lighter.

Right now, the downside seems to be that solid-state batteries are relatively complex to manufacture and mass-produce. As with other automotive technologies we’ve seen morph into the mass market, though, that’s something the manufacturers will get on top of sooner rather than later.

Toyota, for one, is investing heavily (a 2020 report from Japan suggested Toyota is investing as much as $25 billion) in the technology and has flagged that its popular hybrid models will adopt solid-state tech by 2025.

In simple terms, the reason a solid-state battery is ‘better’ technology relates to energy density. A solid-state battery has a higher energy density than traditional batteries, as well as not suffering from the risk of explosion. Solid-state batteries are also more weight- and space-efficient as a result.

And with estimated driving ranges of between 800-1000km on a single charge, as well as the ability to recharge in around 15 minutes, it's easy to see why solid-state batteries are next step in fully electric mobility.