No single detail
Seems like they connected two events solid state batteries , all of them are far away from 2021 and producing first electric car from Toyota
Toyota already makes a hybrid which is more complicated than an electric car. You have an electric drive and a gas drive and you have to make them work together.
It is indeed challenging to make a hybrid. In an all-electric, though, one must have a larger battery that can supply the car's range. That's the challenge that Tesla's met and Toyota has not.
it's a false understanding of an electric car, despite the fact EV is simpler and and more robust, for a large battery, you have to do a lot of engineering. Termal management, hight voltage, safety etc... Toyota's bet was that EV will be slow or stuck in this hybrid world, Reality is pushing it towards different direction.