Nickel-Iron Battery

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

Basic Concepts Behind Construction

The electrochemistry of a Nickel iron battery is similar to a NiCd or NiMH battery in that nickel oxyhydroxide is used as an anode, but iron is used instead of the toxic metal complexes in NiCd and NiMH batteries. During discharge, both metals turn into their hydroxide forms: Ni(OH)2 and Fe(OH)2. (see the wikipedia article under electrochemistry). Given the resilience and rechargeability of the NiFe battery, it should be possible to build it in a discharged state, combining the appropriate hydroxides of Nickel and Iron. Alternatively, the battery could be constructed out of metallic nickel and iron, and the nickel should mostly convert to an NiOOH form after the first discharge-charge cycle.

again, the usual disclaimer applies: this page is a work in progress, and updates will be forthcoming.