MECHANICAL PROCESS FOR ENHANCING METAL HYDRIDE FOR THE ANODE OF A NI-MH SECONDARY BATTERY

This study attempted to find a simpler method for modifying hydrogen storage alloys that are used as anodes in Ni-MH batteries to prolong their cycle life. The alloy was modified by mechanical grinding with cobalt metal powder. A short grinding time yielded samples with a higher-discharge capacity and longer cycle life than those of the alloy which was mixed with the cobalt powder without the mechanical treatment. However, prolonged grinding caused a decrease in the discharge capacity because of amorphization of the alloy by mechanical stress. We believed the formation of a cobalt compound on the alloy surface plus closer contact between particle enhanced the cyclic durability and discharge capacity of metal hydride anodes.