GM invested Billions of dollars into EV prototypes back in 2008-2009
They invested millions into fuel cell vehicles as well
I suspect they threw the knowledge into the trash can because someone came in and decided to take them in a new direction
Detroit teamed up with A123 (the company that designed and built the first lithium batteries)
The cars were terrible looking and were total flops
The Chinese came in an bought the remnants of A123 and just like that the US had lost it's lead in Lithium Ion
The original guys from Tesla realized you needed some sex appeal in a new idea for a car, ran out of money. Elon bought them out using some government money
The Model S was a sexy, fast, outperformed everything comparable and ignited the EV demand
GM was ahead of the game, just did not realize how important pizzaz was.