镍正极中钴添加剂掺入方式的研究

A Study of Doping of Nickel Positive Electrode with Cobalt Additive

以钴作为Ni(OH)2活性物质的添加剂,研究了化学共沉积-表面沉积-机械混合、化学共沉积、表面沉积、机械混合4种掺入方式对镍电极性能的影响。通过恒流充放电对比测试表明,在钴添加剂掺杂量相同的前提下,采用化学共沉积-表面沉积-机械混合分步复合掺入方式的镍电极其放电容量和放电平台得到明显改善和提高。X射线衍射(XRD)和循环伏安(CV)法对镍电极分析表明,分步复合掺入方式的钴添加剂能够在镍电极中能够形成良好的导电网络,充电过程中更能有效的抑制-γNiOOH的生成,提高了析氧过电位,增强了镍电极氧化还原反应的可逆性,提高了活性物质的利用率,大大提高了钴添加剂对镍正极的优化作用。分步复合掺入方式弥补了单一掺入方式的不足,使镍电极表现良好的电化学性能。

Several types of nickel electrodes with same cobalt content were prepared by different cobalt adding methods such as co-precipitation-coating-incorporation, co-precipitation, coating and incorporation. Their charge-discharge performances were tested. The results show that the effect of the cobalt adding method on the modification of the nickel electrode performance is great. The co-preci pitation-coating-incorporation method can improve the performance of the nickel electrodes whereas the others can not. In addition, the effective mechanism of cobalt element is investigated by X-ray diffraction and cyclic voltammetry. The results indicate that adding cobalt by co-precipitation-coating-incorporation method during charging can produce CoOOH with good conductivity, effectively restrain γ-NiOOH creation and increase oxygen over-potential, which is favorable to improve the electrode performance. The fractional complex doping method remedies the deficiency of the single doping methods.