稀土系A_2B_7型La_(1-x)Sc_xNi_(2.6)Co_(0.3)Mn_(0.5)Al_(0.1)(x=0～0.5)储氢合金相结构和电化学性能研究  

Structural and Electrochemical Properties of A_2B_7-type La_(1-x)Sc_xNi_(2.6)Co_(0.3)Mn_(0.5)Al_(0.1)(x = 0～0.5) Hydrogen Storage Alloys

作　　者：梅兴志 罗永春[1,2] 张国庆[1] 康龙[1] 

机构地区：[1]兰州理工大学材料科学与工程学院,兰州730050 [2]兰州理工大学有色金属先进加工与再利用省部共建国家重点实验室,兰州730050

出　　处：《无机材料学报》2015年第10期1049-1055,共7页Journal of Inorganic Materials

基　　金：国家高技术研究发展计划(863计划)(2011AA03A408)~~

摘　　要：真空电弧熔炼制备了A2B7型La1-xScxNi2.6Co0.3Mn0.5Al0.1（x=0～0.5）储氢合金并进行退火热处理。XRD及SEM/EDS分析结果表明,合金退火组织由La2Ni7、La Ni5、La Ni和Sc Ni2等相组成。合金生成焓计算表明,Sc-Ni体系的生成焓比La-Ni和Mg-Ni体系的生成焓更负,这是含Sc合金易于形成Sc Ni2相以及成相规律有别于含Mg合金的主要原因之一。合金电极最大放电容量和循环寿命S100随着Sc含量x增加均呈先增大后减小规律,当x=0.2时,合金电极具有最大的放电容量（267.1 m Ah/g）和较好的容量保持率S100（80.47%）。掺入适量Sc元素后可抑制A2B7型合金的氢致非晶化,但掺入Sc后合金易形成难吸氢的Sc Ni2相,这是合金电极容量不高的主要原因。A2B7-type La1-xScxNi2.6Co0.3Mn0.5Al0.1（x = 0–0.5） hydrogen storage alloys were prepared by vacuum arc melting method and annealed at 1173 K. XRD and SEM-EDS results showed that the annealed alloys mainly consisted of La2Ni7, La Ni5, La Ni, and Sc Ni2 phases. The enthalpy of formation calculation analyses showed that the enthalpy of formation of binary alloy of Sc-Ni was more negative than that of La-Ni and Mg-Ni. This was one of the main reasons that the phase rule of Sc-contained alloy was different from Mg-contained alloy, which facilitated forming Sc Ni2 phase. The electrochemical measurement results showed that the discharge capacity and the cycle stability of the alloys were all firstly increased and then decreased with the x value increasing. The discharge capacity and cyclic stability（S100） of alloy electrodes reached the maximum of 261.1 m Ah/g and 80.47%, respectively, when x value was equal to 0.2. The appropriate amount of Sc in alloy could obviously inhibit the hydrogen-induced amorphous, meanwhile the alloy with Sc content also tends to form the non-hydrogen absorbing Sc Ni2 phase, which is the main reason that the discharge capacity of alloy electrode is not significantly improved.

关 键 词：稀土-镍系A2B7型储氢合金 钪元素替代 相结构 电化学性能 

分 类 号：TG146[一般工业技术—材料科学与工程]