Battery technology has come a long way. Lead acid was the best that we had for a good long while, which is why it sees use in nearly every automobile sold in the world. Now, we have the nickel based battery chemistries and the newest lithium based batteries which are expected to allow the final leap into truly relevant all electric cars. This is all great news to anybody who is concerned with the use of fossil fuels for transportation. But, as more and more power is required to give the performance that we all expect, batteries must continue to get smaller and lighter.
You can't really go smaller than the nanoscale batteries that NASA is working on. NASA is using the iron-containing protein ferritin, which can carry either a positive or negative charge, and layering them in opposing charges. The more layers are added the more power the battery will produce. Smart guys, those NASA folk!
[Source: New Scientist Tech via Engadget]