钴添加剂对发泡式镍电极的作用机理研究

Study on the Contribution of Cobalt Additives to Foam Nickel Electrodes

分别以共沉淀和机械混合两种方式于发泡式镍电极引入钴添加剂.X射线衍射(XRD)、循环伏安、电化学阻抗谱(EIS)和恒电流充放电等测试表明,共沉淀引入的钴添加剂会降低氢氧化镍各晶面衍射峰强度并增大其半峰宽.两种方式引入的钴添加剂均能改善镍电极的电化学活性、提高金属氢化物/镍电池容量,而且以机械混合引入的CoO更有效.但由CoO氧化生成的β-CoOOH在低电位下不稳定,经强制性过放电储存后,电池容量出现不可逆衰减.

Two incorporation ways of the cobalt additives into foam nickel electrodes, i.e. the co-precipitated and admixed method are used. The results of X-ray diffraction （XRD） , cyclic voltammetry, electrochemical impedance spectrum （EIS） and galvanostatic charge-discharge curves show that （ I ） there is a decrease in intensity and increase in half peak breadths of the diffraction peaks of Ni （OH） 2 with co-precipitated cobalt additive; （Ⅱ） the electrochemical activity of nickel hydroxide can be improved by both incorporation ways and the effect of admixed CoO is more notable; （ Ⅲ ）/3-CoOOH derived from admixed CoO is not stable at lower potential, thus results in an irreversible capacity loss of nickel-metal-hydride （Ni-MH） battery after imposed overdischargedstate storage.