纳米二氧化锰的电化学电容性能  

Electrochemical-capacity of nanostructure manganese dioxide

作　　者：张莹[1] 刘开宇[1] 张伟[1] 王洪恩[1] 

机构地区：[1]中南大学化学化工学院,湖南长沙410083

出　　处：《中南大学学报（自然科学版）》2008年第3期469-473,共5页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(50772133)

摘　　要：以MnSO4和K2S2O8为原料，采用液相法制得MnO2并制成电化学电容器电极；采用X射线衍射和扫描电镜对产物进行结构形貌表征，采用恒流充放电、循环伏安、交流阻抗等方法对MnO2电化学电容器电化学性能进行表征。研究结果表明：产物为纳米棒聚集而形成的纳米α-MnO2。充放电曲线由于电极在0．53V和0．36V（vs．Hg／HgO）处发生氧化还原反应而发生了明显弯曲，这有利于比容量的提高；在10^-3～10^4Hz频率范围内，阻抗曲线在0．2Hz以下出现“电荷饱和”，说明电极材料中储存的大部分电容量可得到利用，有效能量为48．3J／g，电极具有良好的倍率特征，其频率响应时间为12．5s；在低频区电极过程由阻挡层扩散控制，比容量可达到151F／g，但随着频率增加，比容量快速下降，100Hz以后比容量开始趋于0。Using MnSO4 and K2S2O8 as reactants, MnO2 was synthesized using fluid phase method and assembled to the electrochemical capacitor electrode. XRD and SEM were used to investigate its structure and morphology, and galvanostastic charge-discharge, A.C. impendence, cyclic voltammetry were used to study the electrochemical performance of the as-prepared electrochemical capacitor, The results show that the product is pure nanostructure α-MnO2, assembled by plenty of nano-robs. The charge-discharge curves bend obviously, resulting from the redox reactions in 0.53 V and 0.33 V （vs. Hg/HgO） respectively, which is helpful to enhance the capacity. In the range of 10^-3-10^4 Hz, ＂charge saturation＂ occurs below 0.2 Hz, showing that most capacitance in the electrode material can be made good use of, and the available power is 48.3 J/g. The rate capability of the electrode is favorable, with the characteristic response time 12.5 s. The electrode process is determined by the block-layer diffusion at low frequency, with a specific capacitance as high as 151 F/g. However, the capacity drops quickly along with the increase of frequency. Below 100 Hz, the capacitance approximates to 0.

关 键 词：纳米二氧化锰 电化学电容器 准电容 

分 类 号：TM53[电气工程—电器] TM911