Benefits of organo‐aqueous binary solvents for redox supercapacitors based on polyoxometallates

Sonia Dsoke, Qamar Abbas

Research output: Contribution to journalArticleResearchpeer-review

Abstract

A novel redox electrolyte based on organo‐aqueous solvent and a polyoxometallate (POM) as redox moiety is proposed. The presence of dimethyl sulfoxide (DMSO) plays a multi‐role 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 12 O 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 1M LiNO 3 / 10 mM H 3 PW 12 O 40 in a mixed DMSO/H 2 O 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 POMs‐containing cell demonstrates a mitigated self‐discharge, due to the strong POMs adsorption into the carbon pores.
Original languageEnglish
JournalChemElectroChem
DOIs
Publication statusPublished - 26 May 2020

Fields of Expertise

  • Advanced Materials Science

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