there are electric cars made more than 115 years ago with the original nickle iron batteries that still work, less capacity than lead batteries, but essentialy idestructable and imortal. there is no reason to equate high power density and low weight with a short life span, and in.the case of capacitive electrical energy storage, we are only waiting for higher energy density, ss it is a true solid state battery, though as every substance that can exist will.hold a charge, the number of possible candidates numbers in the trillions, more, but whatever, and there is an absolute inevitability to creating batteries that will serve humanitys transportation needs. thousands and thousands of smart people work on that every day.