Researchers at Tufts University continue to develop their lithium battery that does not explode or catch fire or even heat up when punctured or cut. Prof. Zimmerman does not use an electrolyte and instead uses a plastic barrier between the anode and cathode. This could be a great leap in safety, and storage capacity, for lithium batteries. But can they scale up production?
There was even a Nova show (Search for the Super Battery) with Prof. Zimmerman.
Prof Mike Zimmerman's page at Tufts. Zimmerman founded a company Ionic Materials to develop the battery.