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铁道科学与工程学报

JOURNAL OF RAILWAY SCIENCE AND ENGINEERING

Vol. 17    No. 3    June 2007

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Charge-discharge process of MnO2 supercapacitor
LIU Kai-yu(刘开宇)1, 2, ZHANG Ying(张 莹)1, ZHANG Wei(张 伟)1,
ZHENG He(郑 禾)1, SU Geng(苏 耿)1

1. School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China;
2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China

Abstract: Mechanochemical synthesis of α-MnO2 was carried out with KMnO4 and Mn(CH3COO)2 in 1׃1 mole ratio. The electrochemical performance of MnO2 electrode was investigated by cyclic voltammograms and alternating current impedance. The charge-discharge process of MnO2 supercapacitor in 6 mol/L KOH was studied within 1.2 V at 200 mA/g, suggesting that it displays double-layer capacibility in low potential scope and pseudo-capacitance properties in high potential scope. It is found that Mn3O4, an electrochemical inert, mainly forms in the initial 40 charge-discharge cycles. During cycling, the pseudo-capacitance properties disappear and the discharge curves are close to ideal ones, indicating double-layer capability. The maximum capacitance of MnO2 electrode is as high as 416 F/g, and retains 240 F/g after 200 cycles. The equivalent series resistance increases from 17 to 41 Ω.

 

Key words: manganese dioxide; supercapacitor; pseudo-capacitance; double-layer capability; charge-discharge process

ISSN 1672-7029
CN 43-1423/U

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