La-Mg-Ni系A_2B_7与A_5B_(19)型相结构储氢合金的电化学性能

Electrochemical Properties of the La-Mg-Ni System A_2B_7-type and A_5B_(19)-type Hydrogen Storage Alloys

系统研究了由较单一的A2B7与A5B19型相结构组成的储氢合金的电化学性能。以La-Mg-Ni系La0.83Mg0.17NixMn0(.1x=3.4,3.6)为研究对象,合金在1173K进行不同时间退火处理,通过XRD及Rietveld全谱拟合方法和扫描电镜背散射分析表明,在1173K退火8h分别可得到较单一的A2B7与A5B19型相结构合金。对较单一的A2B7与A5B19型物相合金进行电化学测试,结果表明:A2B7型相结构储氢合金的活化次数与A5B19型相结构储氢合金的活化次数基本相同,A2B7型物相合金的最大放电容量(386.12mAh/g)略高于A5B19型物相合金的最大放电容量(371.38mAh/g)。A2B7与A5B19型物相合金电极100个循环容量保持率都在85%以上,且差别不大。A5B19型相结构合金的高倍率放电性能(HRD900=85%)高于A2B7型相结构合金的高倍率放电性能(HRD900=76.6%)。

Electrochemical properties of singler type A2B7 and A5B19 phase composition alloys have been investigated systematically. La-Mg-Ni system La0.83Mg0.17NixMn0.1（x=3.4,3.6）hydrogen storage alloy electrode has been explored. Different time annealing treatment at 1173K has been applied to the alloy. XRD and Rietveld refinement method and Scanning Electron Microscopy analysis showed that the alloy annealed at 1173K for 8h singler type A2B7 and A5B19 phase composition can be obtained. Electrochemical measurements of the singler A2B7 and A5B19 phase alloy showed that, the activation properties of singler type A2B7and A5B19 phase composition alloys were the same. The maximum discharge capacity （386.12mAh/g） of A2Bz type phase alloy was slightly higher than the maximum discharge capacity（371.38 mAh / g）of A5B19 type phase alloy. The cyclic stability of alloy electrode of both A2B7 and A5B19-type phase alloy were all very well. The capacity retention rate of 100 cyclic was more than 85%.The high-rate discharge （HRD900=85%）of A5B19 phase alloy was higher than the high-rate discharge （HRD900=76,6%） of A2B7 phase alloy.