【作者】 张睿；

【导师】 郭进；

【作者基本信息】 广西大学 ， 凝聚态物理， 2006， 硕士

【摘要】 AB₃型La-Mg基贮氢合金由于具有较高的放电容量、较为适中的吸放氢平台压力以及活化较快，已成为新型高容量稀土系贮氢电极合金的一个重要研究方向。本论文采用Ar气保护下高频感应熔炼的方法制备AB₃型La-Mg-Ni-Co-Al系列合金，运用X射线衍射、循环充放电、循环伏安，P-C-T测定等手段研究了Al元素对La-Mg基AB₃型贮氢合金电极的贮氢及电化学性能的影响。为新型AB₃型La-Mg基贮氢合金的进一步研究开发打下基础。 研究结果表明： 1．La_0.7Mg_0.3Ni_2.75-xAl_xCo_0.75（x=0.0-0.4）系列合金X衍射分析：在系列合金各样品中，始终存在相Mg₂Ni，由于Al取代了Ni的位置，CaCu₅型固溶相由La（Ni，Co）₅转变为La（Ni，Co，Al）₅；随着Al含量的增加，合金的吸放氢平台压降低，滞后效应减小；Al对合金中Ni的替代，改善了合金氢化物的热稳定性，延长了合金电极的循环寿命，但是合金的活化变得困难，最大放电容量和放电平台有所下降。 2．La_0.7Mg_0.3Ni_2.6Al_xCo_0.5-x（x=0.0-0.5）系列合金X衍射分析表明：在系列合金样品中存在La₂Mg₁₇相、LaNi₃相、Al₁₃Co₄相及CaCu₅型固溶相等四种相结构。随着Al元素对Co元素的替代，六方结构CaCu₅型固溶相先由La（Ni，Co）₅相转变为La（Ni，Al，Co）₅相，最后转变为La(Ni，更多还原

【Abstract】 AB₃-type La-Mg-based hydrogen storage alloys are promising candidates for reversible hydrogen storage because of their high discharge capacities, easy activation and good hydrogen pressure. In this paper, a set of La-Mg-Ni-Co-Al alloys are prepared in high frequency induction furnace under Ar atmosphere. The influences of replacing element in La-Mg based hydrogen storage alloys on the electrochemical properties and the hydrogen storage properties have been studied.1. La_0.7Mg_0.3Ni_2.75-xAl_xCo_0.75 （x=0.0-0.4） hydrogen storage alloys were prepared and the effects of partial substitution Al for Ni on the structure, electrochemical properties of the alloys were investigated systematically. In the alloys, Mg₂Ni phase appears in all alloys and La（Ni, Co, Al）₅ phase with the hexagonal CaCu₅-type structure replaces La（Ni, Co）₅ phase with Al substituting for Ni. The plateau pressure declines gradually and the hysteresis between the hydrogen absorption and desorption decreases with the amount of substitution Al for Ni increasing. The substitution Al for Ni can improve thermal stability for La_0.7Mg_0.3Ni_2.75-xAl_xCo_0.75 （x=0.0-0.4） alloy hydrides, slow更多还原