直封 AAA MH-Ni 电池的研究

Studies on directlysealed AAAsized NiMH batteries

直接封口技术是ＭＨ－Ｎｉ电池的发展趋势，这样可省去开口化成的繁杂工序，降低成本，不污染环境，且电池的均匀性能得到了提高。本文对直封ＡＡＡＭＨ－Ｎｉ电池进行了详细的研究，实验结果表明：电池０．２Ｃ的放电容量可达４２０ｍＡｈ以上，中值电压大于１．２Ｖ，而且电池高倍率放电性能亦良好；电池的自放电率低于２８％；对电池进行１Ｃ连续充放电测得的循环寿命达到５８０次。本文还对ＭＨ－Ｎｉ电池在充放电过程中内压变化进行了初步分析，并发现了电池失效的主要原因是负极合金发生了氧化和正负极活性物质都发生了粉化。

Directlysealing technology, which can avoid the complicated process of formation, lower the cost, protect the environment and improve the homogeneity of the products, is the developing trend of NiMH batteries. Detailed studies have been performed on the AAAsized NiMH batteries in this paper. The experimental results exhibit that the discharging capacity at 0.2C rate is more than 420 mAh, and the mean voltage is higher than 1.2V. Moreover, the discharge property of high rate is very good. The selfdischarge rates of the batteries are lower than 28% and the cyclic lives at 1C reach 580. In this paper the inner pressure changes during charge/discharge process have been analyzed. It is also found that the degradation of the batteries is resulted from the oxidation of negative electrode alloys and the pulverization of both active substances in the negative and positive electrodes.