MH-Ni动力电池性能影响因素与机理的研究

研究了电极材料、结构设计、电解液组成以及化成制度对SC动力型MH-Ni电池性能的影响。实验结果表明:MmNi5基贮氢合金中La含量的提高,合金晶胞体积增大,表面活性提高,改善MH-Ni电池高倍率放电性能,降低电池内压;合金的粒径过于细化,增加了电极间的接触电阻,导致电池高倍率放电性能恶化,合适的粒径分布不仅增加合金的活性表面,又能提高电池的放电平台。镍电极中钴添加剂采取化学共沉积-表面沉积-机械混合分步复合掺入方式,Ni(OH)2晶体形成缺陷,并在化成过程中形成良好的CoOOH导电网络,提高了电池的放电性能;优化的集流结构设计,降低了电子导电阻抗;电解液中Na含量的提高,溶液的电导率下降,不利于电池高倍率放电,但适量的Na能够改善电池的高温性能。对封口电池采用高温预活化制度,合金表面形成微裂纹,产生晶体缺陷,提高了合金的活性;Ni(OH)2晶粒微晶化,产生晶格缺陷,提高质子迁移能力,因此大电流放电性能较好。

Study on influencing factors of performance and mechanism of Ni-MH power batteries

Study on the effects of electrode materials, current colletors design, electrolyte composition and formation systems on SC-3.0 Ah Ni-MH traction batteries for high rate discharge. The experimental results showe that in comparison with that of the conventional MmNi5-based alloy, the high rate dischargeability is enhanced by increasing La content and decreasing Ce content of the alloy composition because of enlargement of the unit cell volume and the improvement of the surface activity. The over-fine particle size increases the contact resistance of the electrode, resulting in a deterioration of high rate dischargeability, a suitable particle size distribution can enhance the alloy activity and discharge plateau. Adding cobalt by co-precipitation - surface coated - mechanical incorporation method make Ni(OH)2 form more lattice defect density and perfectly produce CoOOH with good conductivity in the surface of Ni(OH)2 is there surely better the diffusion velocity of protons/electrons between Ni-metal foam and Ni(OH)2/NiOOH active mass in electrode reactions. A optimizing current colletors design can promote discharge plateau due to decreasing the electrons resistance. The high rate dischargeability is decreased by increasing Na content and decreasing K content of the electrolyte composition because of decreasing conductance. It is also found that a suitable Na content can promote the batteries high-temperature charge efficiency in electrolyte. The negative and positive electrodes exists many defects, lower charge transfer resistance and high electrochemical activity after high-temperature pre-charge formation system for sealed batteries, which results in good high rate dicharge.