The configuration has the potential to deliver faster charging times and make the packs safer by eliminating the flammable electrolyte solution used in lithium-ion batteries, auto executives and analysts say. Still, the technology remains costly and relatively unproven in real-world applications, a hurdle that is expected to take years to solve for the mass market. Toyota Motor Corp. is pursuing in-house development of solid-state battery cells. Earlier this month, the Japanese auto maker said it needed more time to develop the technology for fully electric cars, though it would use smaller solid-state batteries in hybrid vehicles for now. Other major car companies, such as Volkswagen AG , Ford Motor Co. and Bayerische Motoren Werke AG have invested in solid-state battery startups to help them perfect the technology and make it ready for mass production. A number of leading battery startups have so far received around $2 billion in investment […]