Time for some technical talk. Batteries are the true heart of the EV industry, so here’s what you need to know about solid-state batteries, an emerging technology that engineers hope can totally replace more volatile lithium-ion batteries.

Lithium-ion batteries are based around a liquid electrolyte that balances energy flow between the cathode and anode ends of the batteries. They have a longer battery life, better performance in variable temps, and higher energy density than most solid-state batteries.

However, the liquid component also makes them quite heavy, and under certain temperature extremes or improper handling, can outright explode or combust. Remember when Samsung phones kept “exploding” on airplanes? The lithium batteries inside the phones were slightly mis-sized, and when charged in for too long overheated and caught fire.

Obviously, this isn’t something you want to happen to something you’re carrying around in your pocket, let alone a 4,000-pound hunk of metal you’re driving down the freeway.

That’s where solid state batteries come in. Instead of a liquid electrolyte core, solid-state batteries have solid electrolytes, which are inherently more stable. A number of materials can serve as a solid-state electrolyte, including glass and ceramic.
Aside from being less flammable, solid-state batteries are generally faster-charging and more long-lived through charging cycles. Where a lithium-ion battery begins to degrade after 1,000 cycles, a solid-state battery takes closer to 5,000 cycles.
So if they are safer, more durable, more energy-dense, and faster-charging, how come solid-state batteries weren’t used in EV manufacturing before lithium-ion?
Solid-state batteries were originally developed for small devices that didn’t need large batteries to move heavy metal long distances. Think smartwatches, smartphones, and pacemakers. But scaling up solid-state technology is expensive as well as difficult–not every material that performs well as a small-scale electrolyte does as well at a larger scale. Cracking under compression and effective ion conduction are some of the biggest issues.
So when will we get reliable solid-state batteries in our EVs?

Truthfully, we’ll have to wait and see how quickly and how well the technology develops. According to The Next Web, Honda and Toyota are among the automakers that plan to have solid-state battery-empowered vehicles on the market by 2025. But reporting from CarScoops quotes a battery tech CEO that “Right now, despite some of the bullish claims by our rivals, all-solid-state batteries are still at least 10 years away. They are certainly not a silver bullet for any vehicle maker currently developing fast charging electric vehicle architectures.”
The demand is there–but the technology both to build a large solid-state battery and to manufacture it cost-effectively needs to catch up before lithium-ion batteries can become a thing of the past.