微包覆对贮氢电极性能及放电机理的影响

Effects of micro-encapsulation on the performance and discharge mechanism of hydrogen storage alloy electrode

用交流阻抗法、恒电位阶跃法和模拟电池充放电实验,研究了贮氢合金表面微包覆处理前后在不同的放电时刻电极表面的电化学反应阻抗、氢在合金中的扩散系数和电极的放电性能。结果表明,在放电末期电极表面电化学阻抗的急剧增大是引起贮氢合金电极放电终止的主要因素;微包覆铜和钴可促进氢的扩散并显著降低电化学反应阻抗,推迟阻抗增大的时间,因而提高了电极的放电性能。

The electrochemical reaction resistance, the hydrogen diffusion coefficient and the discharge characteristics of MH electrodes at different discharge of depth （DOD） before and after hydrogen storage alloys encapsulated with Co or Cu were investigated by electrochemical impedance spectra （EIS）, the constant potential step method （CPS） and the constant-current charge/discharge test. The experimental results showed that the discharge of MH electrodes terminated with the rapid increase of the electrochemical reaction resistance at the end of discharge; Hydrogen storage alloys coated by Co or Cu could increase hydrogen diffusion coefficient, reduce electrochemical reaction resistance and depress the time of electrochemical reaction resistance increasing, so the discharge characteristics were improved.