摘要
系统地研究了Al含量对富Ce储氢合金MmNi_(4-x)Co_(0.7)Mn_(0.3)Al_x(x=0,0.1,0.2,0.3)电极综合电化学性能,尤其是对低温和高倍率性能的影响。在常温下,储氢合金电极放电容量和循环性能均随着Al含量的增加而增加,而高倍率放电性能严重下降。-20℃时,放电容量仍随着Al含量的增加而增加,但在-40℃下放电容量随之严重衰退。电化学动力学结果表明,常温下高Al合金高倍率性能的降低主要是由于电极表面电荷转移过程的恶化;低温-40℃下,Al同时降低了合金电极的表面电催化活性以及体相H扩散能力,严重恶化电极过程动力学,从而导致了高Al合金极低的容量及电压输出。考虑到各电极的综合电化学性能,MmNi_(3.8)Co_(0.7)Mn_(0.3)Al_(0.2)为最佳的成分配比。
Effects of Al content on the comprehensive electrochemical performance of Ce-rich MmNi4-xCo0.7Mn0.3Alx （x=0, 0.1, 0.2, 0.3） hydrogen storage alloys, particularly the low-temperature and high-rate capacity have been systematically investigated. At room temperature, both the discharge capacity and cycling stability of the electrode increase with the Al content increases, but the high-rate dischargeability seriously deteriorates. The discharge capacity still increases with the increase of Al content at -20℃, but gradually deteriorates when the temperature drops down to -40℃. Electrochemical kinetics results demonstrate that the high-rate capacity recession of the high-Al alloy at room temperature is contributed to the deterioration of the charge-transfer process. When the temperature drops down to -40℃, Al deteriorates both the surface catalytic ability and the bulk hydrogen diffusion ability, leading to the severe drop of discharge capacity and potential of the high-Al alloy. Based on the comprehensive electrochemical properties of the electrodes, the optimal composition of MmNi4-xCo0.7Mn0.3Alx is obtained when x=0.2.
出处
《无机化学学报》
SCIE
CAS
CSCD
北大核心
2017年第10期1881-1888,共8页
Chinese Journal of Inorganic Chemistry
基金
四川省科技创新苗子工程(No.2017RZ0033)资助项目
关键词
AB5型储氢合金
低温电化学性能
Al替代
镍氢电池
电化学动力学
AB5-type hydrogen storage alloy low-temperature electrochemical performance aluminum substitution nickel metal hydride battery electrochemical kinetics
