I watched this Nova documentary "Search for the Super Battery" last night, and found it quite interesting - there wasn't anything I didn't already know as I try to keep up on battery technology but it's a good watch and summary of the situation:
One disclaimer though, the presenter is well known tech Journalist David Pogue, who apparently seems to fancy himself an actor, but just comes across as cringe-worthy in places, especially near the beginning.
But if you can get through the first 5 minutes you should find the rest quite interesting.
Some of the stuff included is a demo of an electric car from 1909 (from Jay Leno's collection of course!) testing of Lithium Ion batteries to destruction, which is frightening to be honest, a demo of a plastic electrolyte battery that is fire and explosion proof, can be cut with scissors or pierced with a screwdriver and keep working, some talk about clean energy generation etc, demonstration of exactly how a lithium Ion cell is made in the lab and whats inside, demonstration of a number of grid storage technologies including flow batteries and flywheels...and a very safe and cheap salt water battery that may (along with flow batteries) be excellent for grid storage in the future... quite a good mix of stuff.