Pseudocapacitive behavior of Mn oxide in aprotic 1-ethyl-3- methylimidazolium-dicyanamide ionic liquid

Jeng Kuei Chang, Ming Tsung Lee, Chi Wei Cheng, Wen Ta Tsai, Ming Jay Deng, Ya Ching Hsieh, I. Wen Sun

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

The electrochemical behavior of anodically deposited Mn oxide was studied in three ionic liquids (ILs): 2-methylpyridine-trifluoroacetic acid (P-TFA), 1-ethyl-3-methylimidazolium-dicyanamide (EMI-DCA), and 1-ethyl-3- methylimidazolium tetrafluoroborate (EMI-BF4). In the aprotic and low-viscosity EMI-DCA IL, ideal pseudocapacitive behavior of the oxide electrode was observed; the specific capacitance, measured using cyclic voltammetry at a sweep rate of 5 mV/s, was 72 F/g. The operation potential window was as wide as 2 V, which is double that found in traditional aqueous electrolytes. Moreover, electrochemical stability of the Mn oxide electrode in EMI-DCA IL was excellent; after 600 redox cycles, the capacitance barely decayed. The charge storage mechanism of Mn oxide in the IL was examined using X-ray photoelectron spectroscopic (XPS) analyses. The results reveal that DCA-, instead of EMI+, is the primary working ion that penetrates into the oxide and compensates the Mn valent state variation. This is the first study that provides a detailed explanation of the pseudocapacitive properties of Mn oxide in IL.

Original languageEnglish
Pages (from-to)3732-3738
Number of pages7
JournalJournal of Materials Chemistry
Volume19
Issue number22
DOIs
Publication statusPublished - 2009

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Chemistry

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