中文摘要：

采用中频感应真空熔炼制备La0．75Mg0．25Ni3．47Co0．2Al0．03合金，并借助电化学和气态循环实验、SEM、XPS等手段对合金电极失效的原因进行研究。结果表明，合金放电容量和吸氢容量的衰减在循环过程中均分为快速和缓慢两个阶段。随循环次数的增加，在电化学循环过程中，合金颗粒表面的氧化腐蚀产物逐渐增多，接触电阻和电荷传递电阻先降低后提高；在气态吸放氢过程中，合金颗粒裂纹逐渐增多，且开裂程度增大。La和Mg的氧化腐蚀损耗是导致合金放电容量衰减的主要原因，而合金颗粒粉化加剧了La、Mg的腐蚀，进一步恶化合金电极的稳定性。

英文摘要：

La0.75Mg0.25Ni3.47Co0.2Al0.03 alloy was prepared by intermediate-frequency induction vacuum melting. The reasons for the efficacy loss of the alloy electrode were investigated by electrochemical and gaseous cycle experiments,SEM and XPS. The results show that capacity attenuation in both discharge and hydrogen absorption cycles takes place in rapid and slow stages. With cycling number increasing,the corrosive oxide on the surface of alloy particle increases during electrochemical cycling, and the contact resistance and charge transfer resistance first decrease and then increase. During gaseous hydrogen absorption and desorp- tion cycling,the crack of the alloy particle increases and the split extent enlarges. The main reason of the alloy electrode capacity decay is the oxidation and corrosion of La and Mg. Alloy particle pulverization ac- celerates the corrosion of La and Mg, and further deteriorates the cycling performance of the alloy electrode.