AB_2和AB_5型贮氢合金电极热碱充电表面改性

SURFACE MODIFICATION OF AB_2 AND AB_5 HYDROGEN STORAGE ALLOY ELECTRODES BY THE HOT-CHARGING TREATMENT

采用高温热碱充电这一表面改性处理新工艺对AB2和AB5型贮氢合金电极性能的影响进行了对比研究．结果表明：该工艺明显改善了AB2贮氢电极的电压平台率（VPR）、高倍率充放电能力（HRDA）、氢的扩散系数DH以及放电容量Cn．通过该工艺处理可使AB2合金表面致富的氧化贮溶解，形成富镍表层；且使合金表面开裂形成新的活性区，有利于改善合金电极的动力学性能，为生产电动车用NiMH电池打下良好的基础．而AB5型贮氢合金由于表面发生腐蚀，故该方法不利于其综合性能的改善．并对电极表面改性机理作了探讨．

The effect of the hot-charging treatment on the performance of AB2 and AB5 hydrogenstorage alloy electrodes is reported. The result shows that it can markedly improve voltage plateau ratio(VPR), high rate discharge ability (HRDA), diffusion coefficient of hydrogen DH and discharge capacityof the AB2 hydrogen storage al1oy electrode by this surface modification. The SEM analysis shows thatthe hot-charging treatment brings about a Ni-rich surface due to the dissolution of zirconium oxides.Moreover, it is very helpful for the improvemeni of the kinetics properties of AB2 hydrogen storage alloyelectrode because the microcracking of the surface results in fresh areas. This can be the basic modificationtreatmeni for NiMH battery used in EVs in the future. But for AB5 type alloy, it has disadvalltages ofimproving the electrochemically synthetic properties, because the surface of the alloy has been corroded.The mechanism of the surface modification of the electrode is also discussed.