電気自動車用ニッケル金属水素化物電池の発熱解析

抄録

Battery development for EV application is quite different from that of consumer battery. In particular, temperature conditions affect battery performances like a cycle life or an energy efficiency remarkably in accordance with a heat generation due to batteries themselves. Accordingly, heat management technologies including the development of battery materials, the structural design of battery module or pack, and the installing system are strongly demanded. The heat behavior of Ni-MH batteries during charge and discharge processes was analyzed and discussed. Heat elements were basically divided to four types of factors corresponding to a battery reaction heat: Q_r, a polarization heat: Q_p, a sub reaction heat: Q_s and a joule heat: Q_j. To minimize the Q_s by introducing an undercharge or a minimum overcharge is effective in order to reduce a heat generation and to increase an energy efficiency during a charge process. And a control technology of oxygen generation from positive electrodes due to a sub reaction of water decomposition is imperative. As an internal resistance of battery dominates a heat generation relating a joule heat and a polarization heat at charge and discharge processes. Eventually, both the material development and the control technology like a charge algorithm should be considered to suppress the total heat generation.