烧结温度对La-Mg-Ni系储氢合金的相结构与电化学性能的影响

Effects of sintering temperature on microstructure and electrochemical characteristics of La-Mg-Ni system hydrogen storage alloys

采用粉末烧结法制备La0.7Mg0.3Ni2.8Co0.5合金,并系统研究1173和1273 K下Ar保护分别烧结12 h所制备合金的微观结构与电化学性能。结果表明:合金均由(La,Mg)Ni3和LaNi52种主相所构成,1173 K条件下却含有少量MgNi2相,而1273 K条件下所制备的合金相结构中不含MgNi2相,这说明高温条件较有利于合金的合成。高温条件下所制备的合金具有较高的放电容量,且循环稳定性和高倍率放电性能均有明显的提高,电化学动力学也随制备温度的增高而改善。

The microstructure and electrochemical characteristics of La0.7Mg0.3Ni2.8Co0.5 hydrogen storage alloy were investigated prepared by powder sintering method at 1 173 and 1 273 K for 12 h.Results showed that the alloy consisted of（La,Mg）Ni3 and LaNi5 phases,besides a bit amount of MgNi2 phase at 1 173 K,but MgNi2 phase vanished at 1 273 K.It indicated that the alloy was synthesized at a higher temperature.The maximum discharge capacity,cycle stability,high rate dischargeability,and electrochemical kinetics were improved with the increasing of the powder sintering temperature.