Electrolyte-assisted hydrogen storage reactions

Abstract

Use of electrolytes, in the form of Li/KBH_4 and Li/K/CsI eutectics, is shown to significantly improve (by more than a factor of ten) both the dehydrogenation and full rehydrogenation of the MgH_2/Sn destabilized hydride system and the hydrogenation of MgB_2 to Mg(BH_4)_2. The improvement revealed that inter-particle transport can be an important rate-limiting step during hydrogen cycling in hydrogen storage materials consisting of multiple phases in powder form (e.g., complex and destabilized hydrides). Electrolytes enable solubilizing heavy ions into a liq. environment and thereby facilitate the reaction over the full surface area of the interacting particles. This work suggests that the use of electrolytes in the form of eutectics, ionic liqs., or solvents contg. dissolved salts may be generally applicable for increasing reaction rates in complex and destabilized hydride materials.