aluminum ion battery
Energy density about the same as lead acid. 7500 cycle life with rapid charging aluminum ion
Forum Discussion
About a year or two ago, I read about a fuel cell which turned aluminum into aluminum oxide (also called an aluminum-air battery although it is not rechargable). It has a lot of energy density, but has to be replaced (the aluminum oxide has to be put in with the piles of bauxite.) This would be useful for something that puts out watts over time to keep the batteries topped off, in addition to solar.
