弱结晶α-MnO_2超级电容器电极EIS分析

EIS Analysis of Weak-crystalline α-MnO_2 Electrode in Supercapacitor

通过机械球磨法制备得弱结晶α-MnO2,并组装成对称型超级电容器进行充放电测试,对充放电若干次后的电极进行电化学阻谱测试。结果表明,电极过程先表现为半无限扩散阻抗特征,然后逐渐表现为有限层扩散阻抗,最后为阻挡层扩散阻抗;电极微分电容从2.40×10-1F减少到1.91×10-3F;交换电流密度先减少到69.8mA/g,经过325次循环后再大幅增加到534mA/g;电极反应电阻先增加到24Ω后减小到5.2Ω,而接触电阻则从0.89Ω增加到1.9Ω。

Equivalent KMnO4 and Mn（CH3030）2 were used to prepare the weak-crystalline a-MnO2 via mechanochemical route, The MnO2 electrode was investigated by A, C, impedance when it was charge-discharge some times. The results suggested that the electrode process displayed for the semi-infinite diffusion impedance characteristic at the beginning cycles, then displayed gradually for the limited level diffusion impedance, finally for barrier diffusion impedance. The electrode differential capacitance decreased from 2.40 ＋ 10^-1F to 1.91 ＋ 10^-3F, The exchange current density reduced to 69.8 mA/g, but after 325 cycles it increasd to 534 mA/g. The electrode reaction resistance increased to 24Ωand then reduces to 5.2Ω, but the contact resistance increased from 0. 89Ω to 1.9Ω.