熔盐法制备λ-MnO_2及其超级电容性能  

Supercapacitor Performances of λ-MnO_2 Prepared in Molten Salt System

作　　者：张春霞[1] 陈野[1] 舒畅[1] 葛鑫[1] 张密林[1] 

机构地区：[1]哈尔滨工程大学材料科学与化学工程学院,黑龙江哈尔滨150001

出　　处：《精细化工》2007年第2期121-124,共4页Fine Chemicals

基　　金：教育部博士点基金资助(20050217019)

摘　　要：在600℃的m(NaC l)∶m(L iC l)=1∶3的熔盐体系中,将KMnO4反应5 h制备了MnO2。X射线衍射分析其结构表明,所制样品为λ-MnO2;扫描电镜对其形貌研究表明,样品为微米级片状结构。按m(MnO2)∶m(石墨)∶m(乙炔黑)∶m(羧甲基纤维素)∶m(聚四氟乙烯)=75∶10∶10∶3∶2制备电极材料,在电解液为c〔(NH4)2SO4〕=2mol/L的三电极体系中,通过循环伏安、交流阻抗和恒流充放电对其超级电容性能进行了考察。不同扫速循环伏安曲线表明,该材料具有典型的超级电容特性;交流阻抗测试结果表明,溶液电阻RL为0.69Ω,电极电阻RE为2.5Ω;用恒流充放电测得在1 mA恒流充放电条件下,放电比容量可达306.92 F.g-1。经5 mA恒电流循环100次,充放电效率接近100%。MnO2 was prepared by decomposition of KMnO4 in a molten salt system of NaCI-LiCI [ m （NaCl） ： m （LiCl） = 1：3 ] at 600℃ for 5 h. Its structure and shape were studied by XRD and SEM. The results show that the sample is A-MnO2 of micro-slice. The electrode material was prepared in the ratio m （ MnOz ） ：m （graphite） ： m （ black ethine） ： m （CMC） ： m （ PTFE ） = 75 ： 10：10： 3 ： 2. The electrochemical properties were tested by cyclic voltammetry, AC impedance and constant current charge/discharge in three-electrode system. The result of CV shows that the material has a perfect supercapacitor performance in the electrolyte of 2 mol/L （NH4）2SO4. The values of RL and RE by test of AC -1 impedance are 0. 69 Ω and 2. 5 Ω respectively. The specific discharge capacitance is 306. 92 F· g when the current is 1 mA. Long cycle life and high coulombic efficiency were also demonstrated after charge/discharge 100 cycles at 5 mA.

关 键 词：超级电容器 熔盐法 A—MnO2 循环伏安 交流阻抗 恒流充放 

分 类 号：TM911[电气工程—电力电子与电力传动]