Variants have been around for a long while, They’re referred to as AGM batteries. I’m a car stereo buff and I’ve been using them for 25 years. They are very efficient and can take huge charges and discharges. A specialized division of Caterpillar also had a patented carbon fiber based battery that was conveniently shelves about 5 years ago. Puff, vaporized
Elon’s stock is at $380, 10X the value since I became interested. lol