Pseudocapacitive mechanism of manganese oxide in 1-ethyl-3- methylimidazolium thiocyanate ionic liquid electrolyte studied using X-ray photoelectron spectroscopy

Jeng-Kuei Chang, Ming Tsung Lee, Wen Ta Tsai, Ming Jay Deng, Hui Fang Cheng, I. Wen Sun*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

51 Scopus citations

Abstract

The electrochemical behavior of anodically deposited manganese oxide was studied in pyrrolidinium formate P-HCOO), 1-butyl-3-methylimidazolium hexafluorophosphate (BMI-PF6), and 1-ethyl-3-methylimidazolium thiocyanate (EMI-SCN) ionic liquids (ILs). The experimental data indicate that the Mn oxide electrode showed ideal pseudocapacitive performance in aprotic EMI-SCN IL. In a potential window of ~1.5 V, the oxide specific capacitance, evaluated using cyclic voltammetry and chronopotentiometry, was about 55 F/g. The electrochemical energy storage reaction was examined using X-ray photoelectron spectroscopy (XPS). It was confirmed that the SCN- anions, instead the EMI+ cations, were the primary working species that can become incorporated into the oxide and thus compensate the Mn 3+/Mn4+ valent state variation upon the charge-discharge process. According to the analytical results, a pseudocapacitive mechanism of Mn oxide in the SCN- based aprotic IL was proposed.

Original languageEnglish
Pages (from-to)11955-11960
Number of pages6
JournalLangmuir
Volume25
Issue number19
DOIs
StatePublished - 6 Oct 2009

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