用冷坩锅磁悬浮熔炼的方法制备了不同化学计量比的La0.7Mg0.3(Ni0.85Co0.15)x (x=3.0, 3.1, 3.2, 3.3, 3.4, 3.5) 稀土镁基贮氢电极合金, 采用X射线衍射和三电极测试体系研究了合金的相结构和电化学性能.X射线衍射分析结果表明, 该系列合金均由(La, Mg)Ni3相、 (La, Mg)2Ni7相、 LaNi5相及少量杂质相组成, 为多相结构;随着化学计量比x的增加, (La, Mg)Ni3相的含量降低, 相应LaNi5相的含量增加.电化学测试结果表明, 该系列合金的最大放电容量均高于目前已商品化的稀土基AB5型贮氢电极合金的最大放电容量(310～330 mAh·g-1), 且当x=3.4时, 合金的最大放电容量可达395.4 mAh·g-1, 较AB5型合金高约30%, 是合金中各相的含量比例较为合适的结果;该系列合金活化性能、倍率放电性能良好, 并随着化学计量比x的增加得到进一步改善, 这与同时作为贮氢相和催化相的LaNi5相含量的增加有关;在电化学吸放氢循环过程中, 合金的循环稳定性较差, 有待进一步提高.
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