Automakers including Toyota, Honda, Mercedes-Benz, and BMW are investing billions in solid-state batteries, with commercial EV deployments targeted for the second half of this decadeScientists now know why solid-state batteries have repeatedly failed. For years, engineers knew how solid-state batteries were failing, but not why. The repeated failures never convinced the auto industry that solid-state batteries were unworkable. Honda has spent approximately $280 million on a 27,400-square-meter solid-state battery production line in Sakura City, Japan. Toyota still expects to introduce its first solid-state batteries during 2027-2028.