材料期刊网

为满足高性能电化学电容器发展的需要,采用循环伏安法(CV)和电化学阻抗谱(EIS)研究了纳米NiO/C复合电极在KOH溶液中的电化学电容特性.这种纳米NiO/C复合电极材料是经热解柠檬酸镍凝胶制得的,由大约85%的纳米NiO和15%的纳米C组成,粉体的比表面积为181m2/g,颗粒粒径＜30nm,微孔直径分布在4～10nm.结果表明,纳米NiO/C复合电极的比电容受KOH浓度和扫描速度的影响,高的电解质浓度和低的扫描速度有助于获得高的比电容.电极的电化学过程研究显示出法拉第反应和双电层特性,因而电极电容由法拉第准电容和双电层电容组成,电极比容量可达116.4F/g.由纳米NiO/C复合电极组成的电容器,其比能量达13.2kJ/kg,比功率达1.6kW/kg,且具有良好的循环稳定性.

For high performances of electrochemical capacitors, this article investigates electrochemical capacitance characteristics of the nano-NiO/C composite electrode, which was fabricated largely by nanosized composite powders of 85 % nickel oxides and 15 % active carbons derived from thermal decomposition of the nickel citrate gel. The nanosized composite powders are characterized with a specific surface area 181m2/g, nanometer particle sizes＜30nm, micro-pore diameter distribution between 4～ 10nm.The electrochemical characteristics of the composite electrode in KOH solutions have been studied by the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The specific capacitance for the nano-NiO/C composite electrode is influenced by the concentration of KOH and sweep rate and high electrolyte concentrations and low sweep rates leads to a high specific capacitance. The electrochemical processes involved may characterize with both kinetically controlled due to faradaic reactions and diffusion controlled due to OH- ion diffusion taking place in the interfaces of electrode/electrolyte and three-dimension frameworks of the electrode active materials. And the electrode exhibited a specific capacitance of 116.4F/g and characterized both the double-layer capacitance and faradaic pseudocapacitance. The electrochemical performances for the prototype capacitor cell have been measured and shown to have a high cycling stability with a specific energy density 13.28kJ/kg and specific power density 1.6kW/kg.