Larger batteries are prohibitively heavy though; electric cars are already pushing the weight up, compensating it with being more powerful, but at the same time they cost more energy to get in motion, which lowers battery life.

Lighter and higher capacity batteries would be ideal, but I'm not sure how feasible that is with current battery tech. I gathered one manufacturer was working on solid state batteries for use in cars, which should give more capacity at the same weight? not sure.