石墨烯包覆对球形Ni(OH)2电化学性能的影响

摘要

采用化学还原法还原石墨氧化物制备了石墨烯聚集物,利用该聚集物对球形氢氧化镍进行了表面包覆.采用X射线衍射(XRD)和扫描电镜(SEM)对其结构和表面形态进行了表征,结果发现,石墨烯包覆在球形氢氧化镍表面,改变了其表面状态,并未影响其结构.运用循环伏安、线性极化法和模拟电池充放电实验等方法研究其电化学性能,结果表明包覆石墨烯后,显著提高了氢氧化镍电极反应的交换电流密度,降低了极化,提高了氧析出的过电位,使充放电性能得到了明显的改善.电极的0.2 C放电容量提高了20％,放电平台电压提高了60 mV;1.0C放电容量提高了39％,放电平台电压提高了110 mV.%Graphene accumulation was prepared by chemical reduction of graphite oxide and it was coated on the surface of spherical nickel hydroxide in this paper. The structure and morphology of the coated nickel hydroxide was studied by using X-ray diffraction and scanning electronic microscope tests. The results show that numerous strip-like particles of graphene aggregated on the surface of the Ni(OH)2 particles and a structure of β-Ni(OH)2 was kept. The results of cyclic voltammetry, linear polarization and galvanostatic charge-discharge tests show that the electrochemical activity of the Ni(OH)2 electrodes with graphene coat can be improved obviously, such as an increase in exchange current density and emanation potential of oxygen gas. The discharge capacity of the electrodes increases by 20% at 0.2 C and 39% at 1.0 C.