GM R&D Group Manager Mei Cai, Ph.D., holds a prototype second-generation Ultium battery cell. GM has completed hundreds of test cycles on the multi-layer prototypes of this next-generation Ultium cell chemistry. Production cells are expected by mid-decade. (Photo by Steve Fecht for General Motors)

GM R&D Group Manager Mei Cai, Ph.D., holds a prototype second-generation Ultium battery cell. GM has completed hundreds of test cycles on the multi-layer prototypes of this next-generation Ultium cell chemistry. Production cells are expected by mid-decade. (Photo by Steve Fecht for General Motors)