CoO对稀土系贮氢合金电化学性能的影响

Effect of CoO on the Electrochemical Properties of Rare Earth Based Hydrogen Storage Alloy

采用傅里叶红外光谱、循环伏安、交流阻抗方法研究了CoO对稀土系贮氢合金电化学性能的影响。结果表明,随着活化次数的增加,放电中值电压逐渐增大,出现第2放电平台,使放电容量进一步提高。0.2C放电时,放电电压和放电容量分别提高0.034V和34.5mAh·g-1;当电流密度为3000mA·g-1时,高倍率放电性能(HRD)提高17.7%。循环伏安(CV)曲线表明,随着扫速的加快,电极的氧化、还原峰位差逐渐加大,可逆性降低,反应向Co生成的方向进行;交流阻抗(EIS)谱表明,添加CoO降低了电极接触电阻和电荷传递阻抗,改善了电化学反应活性。

The effects of CoO additive on the electrochemical properties of rare earth based hydrogen storage alloy were studied by means of FTIR, CV and EIS. The results show that the voltage at half discharge time increases gradually and the second discharge platform appears that further improves the specific capacity with increasing the activation times. When the current density is 60 mA·g^-1, the voltage of discharge and the specific capacity increase by 0.034 V and 34.5 mA·g^-1, respectively. When current density is 3000 mA·g^-1, the high rate dischargeability increases by 17.7%. The CV test shows that the gap between oxidation peak and deoxidize peak enlarges with increasing the scan speed, the reversibility of electrode decreases and turns to form the Co. The EIS test shows that with the addition of CoO, the contact resistance and charge-transfer resistance decrease, and the electrochemical-reaction activity is improved.