纳米无定型MnO_2/炭黑复合电极的电容特性研究

CAPACITIVE CHARACTERISTICS OF AMORPHOUS MnO_2/CARBON BLACK NANOCOMPOSITE ELECTRODE FOR SUPERCAPACITOR

以聚乙二醇和聚乙烯吡咯烷酮为分散剂,加入高比表面积、高导电性的纳米级炭黑,采取化学共沉淀法制备 MnO2/炭黑复合电极材料。借助SEM和XRD分析手段对样品结构及性能进行表征。研究结果表明复合材料为无定型、纳米级粉体。以不同的扫描速度、在不同的电位窗口范围内对MnO2/炭黑纳米复合电极作循环伏安测试和以不同的电流进行恒流充放电测试。结果表明:纳米级 MnO2/炭黑复合电极在1 mol/L的Na2SO4电解质溶液中具有理想的超级电容器特性。复合电极在电位窗口对应于饱和甘汞电极(saturated calomel electrode,SCE)电压为-0.2^+0.8 V范围内,具有良好的电容特性、电化学可逆性和良好的功率特性。复合电极的平均比电容达142.02 F/g。

The nanocomposite electrode material of amorphous MnO2 and carbon black (CB) was synthesized through chemical coprecipitation by using polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) as surfactant and adding nano-carbon black with high specific surface area and high conductivity. The products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results indicate that the composite prepared is amorphous nano-scaled powder. MnO2/CB nanocomposite electrode was measured by cyclic voltammetry (CV) and constant current charge-discharge method using a three electrode system under the conditions of different potential windows, different scanning rates and different current charge-discharge. The amorphous nanocomposite electrode material in 1 mol/L Na2SO4 aqueous electrolyte exhibits ideal capacitive behavior, high reversibility and high pulse charge-discharge property. It indicates that MnO2/CB nanocompostie electrode is a promising electrode material for supercapacitor. The specific capacitance of the composite as high as 142.02 F/g is obtained in the range of -0.2 - +0.8 V corresponded to saturated calomel electrode (SCE).