Elaborating the Iodine/Polyiodide Equilibrium Effects in Nanoporous Carbon-based Battery Electrode via Extreme Mass Asymmetry in Hybrid Cells

Horst Schranger, Saman Khosravi Haji Vand, Harald Matthias Fitzek, Qamar Abbas*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


This article discusses the conversion of electrodeposited iodine to polyiodides within the nanopores of carbon electrodes that affect the performance of iodide electrolyte-based electrochemical cells. Here, carbon electrodes have been polarized in aqueous sodium iodide electrolyte to store charge in the form of solid iodine via highly reversible reaction (2I ⇌I 2+2e ). The stored iodine within the pores interacts with free iodide ions present in the bulk electrolyte via comproportionation reactions leading to polyiodide (I 3 and I 5 ) formations. By tuning the mass asymmetry of carbon electrodes in hybrid cells and using the in-situ Raman spectroscopy on positive battery electrode, we show the influence of iodine/polyiodides equilibrium shifts on the self-discharge and voltage rebounds during open circuit conditions. This study provides insights into the charging mechanisms of carbon electrodes for iodine-based hybrid supercapacitors and battery systems.

Original languageEnglish
Pages (from-to)3155-3160
Number of pages6
Issue number16
Publication statusPublished - 13 Aug 2021


  • hybrid energy storage
  • iodide redox-active electrolyte
  • iodine electrodeposition
  • nanoporous carbon
  • supercapacitor

ASJC Scopus subject areas

  • Materials Science(all)
  • Catalysis
  • Electrochemistry

Fields of Expertise

  • Advanced Materials Science

Treatment code (Nähere Zuordnung)

  • Basic - Fundamental (Grundlagenforschung)

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