钴离子对硫酸中PbO_2电极的影响

Effects of cobalt ion on the PbO_2 electrode in sulfuric acid solution

为研究钴离子对硫酸溶液中PbO2 电极电化学行为的影响机理 ,用循环伏安法、充放电循环实验、X射线衍射技术和扫描电子显微镜技术研究了PbO2 电极的电化学行为和微观结构。结果表明 :硫酸钴的添加有利于提高PbO2 电极的循环寿命与放电容量。尽管硫酸钴的添加同时会引起氧气的析出 ,但当硫酸钴的添加量不高于 6mmol/L时 ,这些不利的影响可以避免。钴离子影响PbO2 电极电化学行为的机理可能是充电过程中钴 (Ⅱ )被氧化为钴 (Ⅲ )离子后 ,与PbSO4发生氧化反应 ,有利于 β PbO2 的生成以改善正极活性物质中 β PbO2 与α PbO2

The effects of cobalt ion on the electrochemical behaviors of PbO_2 electrode in sulfuric acid solution were studied by cyclic voltammetry, charge-discharge cycling experiments, X-ray diffraction and scanning electron microscopy.Test results showed that in the presence of cobaltous sulfate, both the discharge capacity and the cycle life of PbO_2 electrodes were improved. Although the addition of cobaltous sulfate could cause the growth of oxygen evolution, these unfavorable effects could be avoided when the additional quantities of cobaltous sulfate were no more than 6 mmol/L in the electrolyte.The possible mechanism on the effects of cobalt-ion on the electrochemical behavior of PbO_2 electrode was that the addition of cobaltous sulfate could improve the ratio of (β-PbO_2 )and α-PbO_2 in positive active material during overcharge.