The electric vehicle industry is still in its early days. Even though practically every auto manufacturer is developing more and better EVs every year, fewer than one in 10 cars sold in the U.S. is fully electric. One company could change all that. It's not a flashy new automaker. It's the company developing a key technology that could make EVs much more preferable and affordable to own over a traditional combustion engine vehicle. QuantumScape (QS -1.23%) is developing solid-state battery technology that c ...