A lot of money has been poured into battery technology over the last decade or two. We don't have much to show for it. That makes me believe that inventing a better battery is not as simple as it might seem. Coming up with a terrific chemistry is one thing, finding something that is can be manufactured at a good price is something very different.

You can make your own graphene with some charcoal and sticky tape. Graphene is an amazing material, but making it industrially useful is extremely hard.