【摘要】 研究了少量Al替代Mg(x=0.1)对La2Mg1-xAlxNi7.5Co1.5贮氢合金电化学循环稳定性的影响。经过充放电循环后,La2Mg1-xAlxNi7.5Co1.5(x=0.0,0.1)合金中的LaNi3相和αLa2Ni7相仍然保持PuNi3型结构和Ce2Ni7型结构,没有发生变化,此外,在这2种合金中出现少量新的物相La(OH)3,Mg(OH)2和Ni。LaNi3相和αLa2Ni7相吸氢形成氢化物后也保持PuNi3型结构和Ce2Ni7型结构。La2MgNi7.5Co1.5吸氢后,LaNi3相和αLa2Ni7相晶胞均呈各向异性膨胀,但LaNi3相的各向异性膨胀程度及晶胞体积膨胀率明显大于αLa2Ni7相。相比La2MgNi7.5Co1.5氢化物,Al替代Mg对La2Mg0.9Al0.1Ni7.5Co1.5氢化物中的αLa2Ni7相吸氢体积膨胀的抑制作用很小,但Al替代Mg使该氢化物中LaNi3相的c轴膨胀率和晶胞体积v的膨胀率均明显降低。电化学吸放氢循环后合金的粒径变化及形貌观察表明,La2Mg0.9Al0.1Ni7.5Co1.5合金的抗粉化能力优于La2MgNi7.5Co1.5合金,这是Al替代Mg改善La2MgNi7.5Co1.5合金电极电化学循环稳定性的重要原因。更多还原

【Abstract】 In this paper, the influence of small quantity substitution of Al for Mg (x=0.1) on electrochemical cyclic stability of La2Mg1-xAlxNi7.5Co1.5 hydrogen storage alloy has been investigated. After electrochemical charge-discharge cycle, LaNi3 and αLa2Ni7 phase still remain PuNi3-type structure and Ce2Ni7 type structure, however, a small amount new phase La(OH)3, Mg(OH)2 and Ni appear in La2Mg1-xAlxNi7.5Co1.5(x=0, 0.1) alloys. The structure of hydride for LaNi3 and αLa2Ni7 phase after hydrogenizing also remain PuNi3-type structure and Ce2Ni7 type structure. The expansion of LaNi3 cell and αLa2Ni7 phase cell in La2MgNi7.5Co1.5 hydride are anisotropic, but the rate of anisotropic expansion and volume expansion of the former is larger than that of the latter. Compared with the La2MgNi7.5Co1.5 hydride, the repression of volume expansion of αLa2Ni7 phase in La2Mg0.9Al0.1Ni7.5Co1.5 alloy with substitution of Al for Mg is very weak, but the expansion of c axis and cell volume v of LaNi3 phase lowers obviously due to Al substitution. The change of particle size and micrograph of the alloys after electrochemical charge-discharge cycles show that the performance of anti-pulverization of La2Mg0.9Al0.1Ni7.5Co1.5 is superior to that of La2MgNi7.5Co1.5 alloy. That is main reason of improvement of electrochemical cyclic stability of La2MgNi7.5Co1.5 alloy due to substitution of Al for Mg.更多还原