【作者】 张法亮； 罗永春； 阎汝煦； 康龙； 陈剑虹；

【Author】 ZHANG Fa-liang, LUO Yong-chun, YAN Ru-xu, KANG Long, CHEN Jian-hong (Key Laboratory of New Nonferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050, China)

【机构】 兰州理工大学有色金属新材料重点实验室；

【摘要】 用高频感应熔炼的方法制备了La2-xMgxNi7.0(x=0.4,0.5,0.6,0.7,0.8)贮氢电极合金,采用x-ray衍射和XRD粉末衍射全谱拟合分析方法及电化学方法系统研究了随Mg含量的增加,该类合金相结构和电化学性能的变化规律,以及合金在不同退火温度(1123K,1203K,1253K)和不同退火时间(24h,72h,144h)下相结构和微观组织及电化学性能的变化规律.实验结果表明,该类合金由(La,Mg)2Ni7相(Ce2Ni7型结构)、LaNi5(CaCu5型结构)相、(La,Mg)Ni3相(PuNi3型结构)及少量未知相组成.随Mg含量的增加,电极电化学放电容量呈先升高后降低趋势,当x=0.6时达到最大值389.87mAh/g;当Mg含量进一步增加时,电化学放电容量迅速降低,x=0.8时电化学放电容量为188.34mAh/g;随Mg含量的增加,合金组织中(La,Mg)Ni3相和LaNi5相增多.退火处理很大程度上消除了LaNi5相,高温退火有利于(La,Mg)2Ni7相的生成,低温退火有利于(La,Mg)Ni3相生成.退火时间的延长对合金相结构影响不明显,但提高了合金组织均匀性,同时使电化学放电容量降低.不同的退火温度和退火时间对未知相影响不明显.本文研究表明,退火温度对(La,Mg)2Ni7合金相结构有重要影响,Mg含量是影响合金相结构和电化学放电容量的关键.更多还原

【Abstract】 The La2-xMgxNi7.0( x=0.4, 0.5, 0.6, 0.7, 0.8) hydrogen storage alloys were prepared by induction melting under Ar gas and the phase structure and electrochemical properties of the alloys were studied systematically at different heattreatment conditions. The experimental results showed that all these alloys consisted of (La,Mg)Ni3 phase, (La,Mg)2Ni7 phase ,LaNi5 phase and a little amount of unknown phase. The electrochemical discharging capacity increases firstly with increasing Mg, then decreases, The maximal capacity is 389.87mAh/g when x=0.6, meanwhile, the electrochemical discharging capacity of x=0.8 alloy is only 188.34mAh/g. the amount of the ( La, Mg) Ni3 phase and LaNi5 phase increase with increasing x. Heat treatment eliminated the LaNi5 phase greatly. High temperature is in favor of forming (La,Mg)2Ni7 phase, while Low temperature prefers to the forming of (La,Mg)Ni3 phase. Prolonging the time of heat treatment improved the homogenizations of alloys, but not changed the structure of phases obviously, meanwhile decreasing the electrochemical discharging capacities. Heat treatment didn’t influence the unknown phase distinctly. The research shows that heat treatment temperature influences the phase structure of alloys greatly, meanwhile the ration of Mg is key to influence the phase structure and the electrochemical discharging capacity.更多还原