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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。
The effect of Al content on the electrochemical performance of MmNi_ (4-x) Co_ (0.7) Mn_ (0.3) Al_x (x = 0,0.1,0.2,0.3) electrode was investigated systematically, especially for low temperature and high temperature Effect of rate performance. At room temperature, the discharge capacity and cycle performance of hydrogen storage alloy electrode increase with the increase of Al content, while the discharge performance at high rate decreases seriously. At -20 ℃, the discharge capacity still increases with the increase of Al content, but the discharge capacity decreases seriously at -40 ℃. The results of electrochemical kinetics show that the decrease of high rate capability of high Al alloy at room temperature is mainly attributed to the deterioration of the surface charge transfer process. At low temperature of -40 ℃, Al also decreases the surface electrocatalytic activity and bulk phase H diffusion Ability to severely degrade the electrode process kinetics, resulting in very low capacity and voltage output of high Al alloys. Considering the comprehensive electrochemical performance of each electrode, MmNi_ (3.8) Co_ (0.7) Mn_ (0.3) Al_ (0.2) is the best composition ratio.