Research on Life Assessment of Ni-MH Battery through Orthogonal Experiment under Multiple Aging Factors

Abstract

The power battery is required to have the same service life as the hybrid vehicle. The cylindrical Ni-MH battery 600DC has been used in many HEVs, which was produced by Shona-Corun Energy Co., Ltd (Shona) in Japan. Recently, Shona has been acquired by Hunan Co-power EV Battery co., LTD (CPEV), and an improved and localized 600DE NiMH battery was produced in China. Therefore, it is necessary to study the cycle life of the battery according to the requirements of the real vehicle. The orthogonal experimental scheme based on characteristic conditions including battery temperature, SOC average value, DOD range and average current was designed. According to the periodic assessment during the aging cycle and the physio-chemical analysis after the aging cycle, it is proved that the depth of DOD has a significant impact on the life aging. The main factors of the performance degradation of the battery are the pulverization and corrosion of the negative alloy, the reduction of the active material Ni (OH)2 and the production of the inert material Ni2O3H in the positive electrode.