X-ray absorption spectroscopic study of sodium iodide and iodine mediators in a solid-state supercapacitor

Azzam N. Mansour, Juanjuan Zhou, Xiangyang Zhou

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

In situ X-ray absorption spectroscopy was used to provide the redox states of the NaI/I2 mediators in an all-solid-state mediator-enhanced supercapacitor during the charge/discharge processes. Results show that in the charge process from -0.08 (open-circuit voltage (OCV)) to 0.80 V at constant current of 5 mA, all of the I- ions were oxidized to I2. However, in the discharge process from +0.80 V to OCV at constant current of -5 mA, only I3- ions were detected indicating that the I2 molecules were reduced to I3- ions. Upon a negative polarization from OCV to -0.80 V at constant current of -5 mA, the I3- ions were reduced to I- ions. Based on combined in situ XAS and cyclic voltammetry data, we show that the I-/I2 redox couple proceeds via the formation of I3- ions as an intermediate step.

Original languageEnglish (US)
Pages (from-to)270-276
Number of pages7
JournalJournal of Power Sources
Volume245
DOIs
StatePublished - Jan 1 2014

Keywords

  • Capacitor
  • Iodine
  • Redox state
  • Sodium iodide
  • XAS Mediator

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Energy Engineering and Power Technology
  • Renewable Energy, Sustainability and the Environment
  • Physical and Theoretical Chemistry

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