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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。
The La0.75Mg0.25Ni3.47Co0.2Al0.03 alloy was prepared by medium frequency induction vacuum melting. The causes of the failure of the alloy electrode were studied by means of electrochemical and gas circulation experiments, SEM and XPS. The results show that the alloy discharge capacity and hydrogen absorption capacity of the decay in the cycle are divided into two stages of rapid and slow. With the increase of the number of cycles, the oxidation corrosion products on the surface of the alloy particles gradually increase and the contact resistance and the charge transfer resistance decrease first and then increase during the electrochemical cycling. In the case of gaseous hydrogen absorption and desorption, the grain cracks gradually increase and the cracking Increased degree. Oxidative corrosion loss of La and Mg is the main reason that causes the discharge capacity of the alloy to decay, and the alloy particles pulverization aggravates the corrosion of La and Mg, which further deteriorates the stability of the alloy electrode.