There are a few new types of battery tech coming out - one is basically a gel made with carbon nanotubes for the dielectric (faster charging and greater capacity) and the other is a modified Lithium-ion battery, which came about by accident! (4x as many charges before capacity is affected)
A few years back I worked for Toyota forklifts and quizzed one of the technology guys as they were wafting fancy drafts of future electric technologies and even hydrogen around in a presentation. Details were glossed over, but being a bit of a nerd I wanted to know more. I was told Lithium Ion was definitely not the route forward, in high power applications they couldn't tame thermal runaway, so fine for microelectronics, not good for power apps. He was shadey about the actual solution, got a politician's answer, but my money's on carbon nanotubes as they seem to offer a good blend of physical properties and cost.
If anyone has a definitive answer it's Elon Musk, that man's invested a lot of money in cell production.