高功率型镍氢电池的循环性能

由于没有镉污染,对环境友好,用于高功率设备的镍氢电池的需求量增长很快,目前每年的需求量约为5亿只.但是镍氢电池的一些性能还不能完全满足电动工具的使用要求,突出表现在电池大电流充放循环寿命较差.因此,研制高性能的高倍率镍氢电池不仅具有重要的研究意义,也有很大的应用价值.本文研究影响SC型动力电池循环寿命衰减的主要因素,测量了在大电流循环过程中镍氢电池的内阻、温度及重量变化,并运用SEM、XRD对电池内阻升高的原因进行了分析.我们认为电池内阻升高是镍氢电池大电流循环寿命差的主要原因,分析发现在镍氢电池进行大电流充放电循环时,电池正极膨胀,负极微粉化,电池内部孔隙率增加,致使电解液干涸,电池内阻升高.通过增加负极容量,抑制正极膨胀,可以有效改进镍氢电池大电流充放时的循环性能.

The Cycle Life Performance of MH-Ni Batteries for High Power Applications

Because of few environment pollution of Ni/MH battery compared with Ni/Cd battery, the demand of the high-rate cylinder nickel metal hydride battery is growing in high power applications, and the annual consume amount is above 5 hundred millions. But now some performances of Ni/MH battery can't meet the requirement for usage of electrical tools, especially the poor charge&discharge cycle life. So the development of high-rate nickel metal hydride battery with high performance is very important both in the scientific research and the market applications. The mainly contents in this paper are the study of effects on the charge&discharge cycle life and degradation of sub-C type Ni-MH power batteries. The change of impedance, temperature, and weight loss are investigated in the process of cycle life test. The cause for increase of battery internal resistance is also analysis by SEM method. We think increase of the internal resistance of battery is the main problem to the poor cycle life at high rate, besides the performance deteriorates of the electrode materials. Swell occurred on positive and pulverization on negative electrode at high rate current, make the pore space increased and the electrolyte depleted. The restrains of swelling and the increase of capacity of negative electrode can improve the performance of cycle life.