Ni／MH电池负极用高容量稀土-镁-镍基储氢合金

Structural and Electrochemical Properties of High-Capacity Ml-Mg-Ni Based Hydrogen Storage Alloys

通过感应熔炼方法制备了稀土-镁-镍基储氢合金Ml0.88Mg0.12Ni3.0Mn0.10Co0.55Al0.10(Ml代表富镧混合稀土).采用XRD和SEM分析了合金的微观结构,发现该合金主要由CaCu5型相、Ce2Ni7型相和Pr5Co19型相组成.电化学测试结果表明:合金的放电容量可以达到386 mA.h/g,比商品AB5型合金(332 mA.h/g)高出16.3%;在1 100 mA/g的放电电流密度下,合金的高倍率放电性能可以达到62%,高于商品AB5型合金(45%);充放电循环300次后,合金的放电容量降低到315 mA.h/g,为最大放电容量的81.5%.

The rare earth-Mg-Ni-based hydrogen storage alloy Ml0. 88 Mg0. 12 Ni3.0 Mn0. 10 Co0. 55 Al0.10 （Ml=La-rich mishmetal） was prepared by inductive melting. The micro-structure was analyzed by XRD and SEM. The alloy consists primarily of CaCu5-type phase, Ce2Ni7 -type phase and Pr5Co19-type phase. The electrochemical measurements show that the maximum discharge capacity reaches to 386 mA·h/g, 16.3% higher than that of the commercial AB5-type alloy （332 mA·h/g）. For the discharge current density of 1 100 mA/g, the higher rate discharge ability gets 62%, while that of the commercial AB5-type alloy is only 45%. The discharge capacity decreases to 315 mA·h/g after 300th cycle, 81.5% of the maximum discharge capacity.