Investigation on capacity fading of aqueous MnO2•nH2O electrochemical capacitor

JOURNAL OF POWER SOURCES

卷:177

Article

Hsieh, Yi-Chien¹  Lee, Kuang-Tsin¹  Lin, Yen-Po¹  Wu, Nae-Lih¹  Donne, Scott W.² 

[1] Natl Taiwan Univ, Dept Chem Engn, Taipei 106, Taiwan

[2] Univ Newcastle, Discipline Chem, Callaghan, NSW 2308, Australia

关键词: electrochemical capacitor;    MnO2;    cycle stability;    capacity fading;   

DOI  :  10.1016/j.jpowsour.2007.11.026

来源: Elsevier

【 摘 要 】

Cycle stability of MnO2 center dot nH(2)O electrochemical capacitors (ECs) has been studied by using galvanostatic tests and electrochemical impedance spectroscopy (EIS). The extent of capacity fading, ranging from 5 to 30% in 1000 cycles, increases with current-rate, and is markedly reduced with increasing binder content. Two fading mechanisms have been identified. With low binder content, and at high current-rate, capacity fading occurs in conjunction with appreciable increase in transmission resistance, suggesting progressively deteriorating electric contacts among the pseudocapacitive oxide particles and conductive carbon. The mechanical failure of the electrode structure may arise from the cyclic volumetric variation of the pseudocapacitive oxide particles as previously reported. With high binder content or at low current-rate, capacity fading is associated with increasing interfacial charge-transfer resistance upon cycling, which has a less pronounced effect than the mechanical failure mechanism. (C) 2007 Elsevier B.V. All rights reserved.

【 授权许可】

Free