Patent ID: 7632604

Claim:
An energy storage device, comprising: a separator having a first surface that defines at least a portion of a first chamber, and a second surface that defines a second chamber, and the first chamber is in ionic communication with the second chamber though the separator; and a plurality of cathodic materials comprising at least a first cathodic material and a second cathodic material, both cathodic materials being in electrical communication with the separator and both cathodic materials having a reduced state and an unreduced state, the unreduced state comprising a metal halide, wherein the first cathodic material has a first electric potential that differs from a second electric potential of the second cathodic material, the energy storage device configured such that upon the first cathodic material being fully in the reduced state, the energy storage device electric potential changes from the first electric potential to the second electric potential, with the proviso that if either of the first cathodic material or the second cathodic material is a transition metal, then the other of the first cathodic material and the second cathodic material is not iron, arsenic, or tin.