Electrochemical performances of AB5-type hydrogen storage alloy modified with Co3O4

来源期刊:中国有色金属学报(英文版)2011年第6期

论文作者:张青青 苏耿 李傲生 刘开宇

文章页码:1428 - 1434

关键词:Co3O4;储氢合金;容量;电化学性能

Key words:Co3O4; hydrogen storage alloy; capacity; electrochemical performance

摘    要:

将不同含量的Co3O4(2%,4%,6%,8%,质量分数)作为添加剂加入到储氢合金中,采用机械混合法进行改性处理。对添加Co3O4的合金电极的电化学性能和电极过程进行研究。结果表明:放电容量有了较大增加,添加2%、4%、6%、8% Co3O4的电极放电容量比空白电极容量分别增加0.83%, 4.86%, 7.18% 和 9.21%。线性极化曲线和电化学阻抗谱测试表明,添加Co3O4降低了电极的电荷转移电阻。循环伏安、扫描电镜和EDS测试表明,添加的Co3O4可部分溶解,发生Co-Co(OH)2可逆氧化-还原反应,从而改善储氢合金的电化学性能。

Abstract:

Anodic electrodes with the mixture of hydrogen storage alloys and different contents of Co3O4 (2%, 4%, 6% and 8%, mass fraction) powders were made. The effects of Co3O4 on the electrochemical performance of the alloy electrodes were studied. The constant charge-discharge tests show that the discharge capacity of alloy electrodes with Co3O4 significantly increases, and the maximum discharge capacities of electrodes with 2%, 4%, 6% and 8% Co3O4 are higher than the electrode with no Co3O4 by 0.83%, 4.86%, 7.18% and 9.21%, accordingly. Linear polarization (LP) and electrochemical impedance spectroscopy (EIS) tests suggest that charge-transfer resistance decreases by the addition of Co3O4. Cyclic voltammogram (CV), scanning electron microscopy (SEM) and energy dispersive spectrum (EDS) tests indicate that Co3O4 can partly dissolve and experience a reversible oxidation-reduction process of Co to Co (OH)2, leading to the improvement in the electrochemical performance of hydrogen storage alloy.

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