Benefits of Organo-Aqueous Binary Solvents for Redox Supercapacitors Based on Polyoxometalates

Sonia Dsoke*, Qamar Abbas

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

A novel redox electrolyte is proposed based on organo-aqueous solvent and a polyoxometalate (POM) redox moiety. The presence of dimethyl sulfoxide (DMSO) plays multiple roles in this system. Firstly, it enhances the cathodic electrochemical stability window by shifting the H 2 evolution to lower potentials with respect to pure aqueous systems; secondly, it improves the reversibility of the redox reaction of the PW 12O 40 3− anion at low potentials. The presence of DMSO suppresses the Al corrosion, thus enabling the use of this metal as the current collector. An activated carbon-based supercapacitor is investigated in 1 M LiNO 3/10 mM H 3PW 12O 40 in a mixed DMSO/H 2O solvent and compared with a POM-free electrolyte. In the presence of POMs, the device achieves better stability under floating conditions at 1.8 V. At 1 kW kg −1, it delivers a specific energy of 8 Wh kg −1 vs. 4.5 Wh kg −1 delivered from the POM-free device. The H 2 evolution is further shifted by the POMs adsorbed on the activated carbon, which is one reason for the improved stability. The POM-containing cell demonstrates a mitigated self-discharge, owing to strong POMs adsorption into the carbon pores.

Original languageEnglish
Pages (from-to)2466-2476
Number of pages11
JournalChemElectroChem
Volume7
Issue number11
DOIs
Publication statusPublished - 2 Jun 2020

Keywords

  • electrolyte
  • heteropolytungstate
  • polyoxometalates
  • redox supercapacitors
  • water/dimethyl sulfoxide mixtures

ASJC Scopus subject areas

  • Catalysis
  • Electrochemistry

Fields of Expertise

  • Advanced Materials Science

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