Missing pieces of the puzzle or about some unresolved issues in solid state chemistry of alkali metal aluminohydrides

Abstract

The paper discusses some unresolved issues in the solid state chemistry of alkali metal aluminohydrides (alanates) relevant to high-capacity hydrogen storage. Analysis of experimental data available in chemical and materials science literature suggests a one-step mechanism for the thermal decomposition of both pure and Ti-doped aluminohydrides. Most likely, the presence of a titanium hydride phase in the catalyst is responsible for the catalytic effect of Ti-additives. Furthermore, ball-milling promotes chemical and phase transformations of solid alanates by enhancing mass transfer in the material and creating high-pressure spots where pressure-driven chemical reactions can take place.