钴的添加对涂膏型镍电极电化学性能的影响

Effects of cobalt addition on electrochemical performance of pasted nickel electrodes

以发泡镍作为电极基体,将金属Co粉以不同比例添加到氢氧化镍粉末中制备了涂膏型镍电极。采用恒电流充放电测试、循环伏安(CV)及交流阻抗分析(EIS)等方法对镍电极的电化学性能进行了研究。结果表明,Co的添加可以使镍电极的放电比容量、活性物质利用率、抗膨胀能力及循环稳定性等得到明显改善和提高,但Co也会降低镍电极的放电电位,因此其添加量要适当控制,一般以3%～5 %(质量百分数)比较适宜。添加有Co的镍电极具有更高的反应活性及更小的电化学反应阻抗,因而表现出优良的电化学性能。

The pasted foam-nickel electrodes were prepared with various amounts of the addition of cobalt metallic powder to nickel hydroxide powder. Constant current charge/discharge tests, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize the electrochemical performances of the pasted nickel electrodes. Results show that in comparison with that of the nickel electrode without cobalt addition, the nickel electrodes with cobalt powder addition exhibit better performances in the specific discharge capacity, active material utilization, resistance to swelling with cycling and cycle stability. Meanwhile, the cobalt addition also lowers the discharge potential of the pasted nickel electrodes, so the amount of cobalt addition to the nickel electrodes should be controlled, and an appropriate amount of addition is 3%~5%(mass percentage). The superior electrochemical performances of the nickel electrodes with the cobalt addition can be attributed to the higher reaction activity and lower electrochemical impedance.