Hydrogen storage alloys having a high porosity surface layer

Abstract

Electrochemical and thermal hydrogen storage alloy compositions that provide superior performance, including an electrochemical hydrogen storage alloy that provides superior low temperature discharge characteristics. The alloy compositions include microstructures in the interface region that are highly porous and that include catalytic metallic particles. The microstructures include a large volume fraction of voids having spherical or channel-like shapes and are sufficiently open structurally to facilitate greater mobility of reactive species within the microstructure and in the vicinity of catalytic metallic particles. Greater accessibility to reactive sites accordingly results. The greater mobility of reactive species and/or the greater density of catalytic particles lead to faster kinetics and improved performance (e.g. higher power), especially at low operating temperatures. The microstructures may be formed through inclusion of a microstructure tuning element in the alloy composition, through control of processing conditions and/or through inclusion of etching steps in the post-formation processing of hydrogen storage alloys.