Nickel/metal hydride batteries using rare-earth hydrogen storage alloy

Abstract

Fine particles of a hydrogen storage alloy (LaNi3.8Co0.5Mn0.4Al0.3) were microencapsulated with a thin film of nickel of about 0.6 μm thickness. The microencapsulated alloy powders were used as an anode material in a sealed nickel/metal hydride battery. The battery characteristics were compared with those of a battery with a bare (uncoated) alloy anode. The battery using the bare alloy was less stable compared to the coated alloy due to the role of the coated nickel as an oxygen barrier for protecting the alloy surface from oxidation. In addition, charge-discharge characteristics were improved greatly by the nickel coating, especially at high rates and at low temperatures due to the role of nickel as a microcurrent collector. So the microencapsulation of the alloy powders improves the performances of the alloy electrode.