Solid-state batteries are thought to be the next be breakthrough for electric cars and Toyota might be preparing to unveil a prototype car using this next-gen battery tech in 2021.

The report from Nikkei Asia says that Toyota wants to be the first to sell an electric car with a solid-state battery in "the early 2020s". It's said that the EVs will have double the range of current lithium-ion batteries used in current models, while Toyota has over 1000 patents around solid-state batteries.

Current EVs have been increasing range by increasing the physical size of the batteries and increasing the density of the cells used within those batteries. But current lithium-ion batteries have downsides - one being the level of protection needed to keep them safe, the management to maintain efficiency, the charging speeds and limited lifespan of liquid-based batteries.

While charging speeds for EVs have been improving, it's thought that solid-state batteries will bring a big step forward, offering much greater power density and faster charging, while also lasting through more charge-discharge cycles than current batteries that rely on an aqueous electrolyte.

Toyota aren't the only company looking at solid-state. Most major manufacturers are involved in some way, as are many of the big chemical companies responsible for current power solutions.

But having a prototype on the road would set a new milestone for the electric car industry as we move towards increasing the viability of solid-state batteries as a commercial solution for electric cars.

Don't get too excited though, because we know that these things take a long time and we're not expecting to see a mainstream shift over to solid-state batteries until the second half of this decade at the earliest.