They are developing a battery that uses radioactivity to provide years of automatic recharging. Carbon-14 contained in irradiated graphite is press into diamonds, then surrounded by another layer of non-radioactive diamond. The beta decay generates a charge that is captured by the surrounding solid-state structure and passed on to an external circuit. Essentially it's a self-charging battery with a power density higher than today's lithium ion batteries. You could have an i-Phone that could fully recharge itself from zero to full charge 5 times an hour. The battery is practically indestructible and could be scaled up for automobiles.