"..."It's true. There has not been a major change in battery chemistry since lithium-ion," says Dr. Lawrence Dubois, vice president in the physical sciences division of SRI International, a nonprofit research and development company. "We are not seeing the doubling or tripling of battery life that we'd like."
Link. Yeah, I know you know about fuel-cells etc. This is just a reminder of the massive market niche awaiting the first mover.