DEGRADATION SPEED JUDGING METHOD FOR HYDROGEN STORAGE ALLOY POWDER FOR SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To judge whether the degrading speed of a secondary battery due to repetitive charge and discharge lies within the normal range, wherein the secondary battery uses a gas atomize powder of a hydrogen storage alloy in which misch metal and nickel alloy are mixedly melted. SOLUTION: A secondary battery is formed using a gas atomize powder of a hydrogen storage alloy consisting of a misch metal and nickel alloy, and inspection is made as to whether the half value width (2θ) of the peak in the X-ray diffraction pattern after heat treatment has decreased more than 15% from before the heat treatment, or whether the peak half value width of the diffraction pattern of X-rays after heat treatment is below 0.6 deg. in case where the (301) diffraction peak of CuKαline is used as the X-ray diffraction pattern. If yes, it is judged that the degrading speed lies within the normal range.