The most promising new battery technology is solid-state batteries. These are seen as the next generation of EV batteries, as they're smaller, lighter, and more efficient than traditional lithium-ion batteries. Solid-state batteries are also safer, as they don't overheat or catch fire in the same way that lithium-ion batteries can. However, this technology is still in its early stages, so it will be some time before we see solid-state batteries in electric cars on the market.