无镨钕La_(1-x)Ce_x(NiCoMnAlCuSnFeB)_(5.1)贮氢合金的电化学特性

The electrochemical properties of La_(1-x) Ce_x ( NiCoMnAlCuSnFeB )_(5.1) hydrogen storage alloys

采用真空电弧熔炼-热处理制备了一系列无镨钕稀土基AB5型贮氢合金,研究了Ce掺杂量对贮氢合金La1-xCex(NiCoMnAlCuSnFeB)5.1的相结构、吸放氢PCT曲线和电化学性能的影响.XRD分析结果表明,该系列贮氢合金均为CaCu5型六方结构,晶胞体积随Ce含量的增加而减小.由合金的吸放氢PCT曲线可知,随Ce含量的增加,合金的吸氢平台压升高而吸氢量减少.对合金的电化学性能测试结果表明,随Ce含量的增加,合金的电化学容量减小而电化学稳定性则有所改善.在La1-xCex(NiCoMn-AlCuSnFeB)5.1贮氢合金中,当Ce含量(原子分数)为0.15～0.23时,合金在0.2C的放电比容量为349.5～333.1mA.h/g,高倍率放电性能HRD7C为75.53%～73.21%,当合金电极的容量保持率Sn为80%时,合金电极的充放电循环次数为269～365次.

The Pr-free and Nd-free AB5 type rare-earth-based hydrogen storage alloys are prepared by an in- duction furnace melting-heat treatment process. The characteristics of these alloys are investigated by means of XRD, PCT and measurement of electrochemical capacity. The results from XRD indicate this se- ries of hydrogen storage show a hexagonal structure of CaCu5-type, and the volume of their until cells in these alloys decrease with Ce content increasing. The PCT curves exhibit that the pressure of hydrogen ab- sorption in plateau rises and hydrogen storage capacity of alloys increases with Ce content increasing. Elec- trochemical measurements show that discharge capacities of alloys La1-x Cex （NiCoMnAlCuSnFeB）5.1 de- crease and electrochemical cycling stability inceases with Ce content increasing. When the Ce content is 0.15-0. 23（atomic number） ,the discharge capacities of these alloys at a rare of 0. 2C are 349.5-333.1 mA .h/g, and high rate discharging capabilities are 75.53%-73.21% at 7C rare, and discharge capacities of al- loy electrodes reduce to 80% of its initial discharge capacity after 269-365 cycles.