Improved Performance of Solid-State Metal Hydride Batteries Using Heteropolyacid Hydrate as an Electrolyte

Abstract

In order to enhance the electrochemical performance of our solid-state metal hydride battery using an electrolyte of heteropolyacid hydrate, such as 12-molybdophosphoric acid hydrate (H₃PMO₁₂O₄₀·20H₂O), we tried to improve the total battery construction; the interface between electrode and electrolyte was increased and the electrolytic manganese dioxde was adapted as a positive electrode material instead of reagent grade manganese dioxide previously used. The resultant battery exhibited remarkablv longer cycle life performance, higher discharge efficiency, and lower po larization than the previous one. The high rate charge-discharge characteristics was improved significantly by optimiz ing electrolyte content in the positive electrode; the battery was able to operate over 200 cycles at 10 mA g (alloy)^-1.