This looks kinda cool

[Caydr]

Basically a new kind of battery, vaguely similar in capability to a mixture of ultracapacitors and super-duper-lithium batteries. Also, smaller for equivalent capacity... longer shelf-life...

http://en.wikipedia.org/wiki/EEStor

The "skepticism" section had be... skeptical... but they have a lot of big investors and Lockheed-Martin bigshots are apparently very impressed with their factory.