Persistent and reversible solid iodine electrodeposition in nanoporous carbons

Christian Prehal*, Harald Fitzek, Gerald Kothleitner, Volker Presser, Bernhard Gollas, Stefan A Freunberger*, Qamar Abbas*

*Korrespondierende/r Autor/-in für diese Arbeit

Publikation: Beitrag in einer FachzeitschriftArtikelBegutachtung

Abstract

Aqueous iodine based electrochemical energy storage is considered a potential candidate to improve sustainability and performance of current battery and supercapacitor technology. It harnesses the redox activity of iodide, iodine, and polyiodide species in the confined geometry of nanoporous carbon electrodes. However, current descriptions of the electrochemical reaction mechanism to interconvert these species are elusive. Here we show that electrochemical oxidation of iodide in nanoporous carbons forms persistent solid iodine deposits. Confinement slows down dissolution into triiodide and pentaiodide, responsible for otherwise significant self-discharge via shuttling. The main tools for these insights are in situ Raman spectroscopy and in situ small and wide-angle X-ray scattering (in situ SAXS/WAXS). In situ Raman confirms the reversible formation of triiodide and pentaiodide. In situ SAXS/WAXS indicates remarkable amounts of solid iodine deposited in the carbon nanopores. Combined with stochastic modeling, in situ SAXS allows quantifying the solid iodine volume fraction and visualizing the iodine structure on 3D lattice models at the sub-nanometer scale. Based on the derived mechanism, we demonstrate strategies for improved iodine pore filling capacity and prevention of self-discharge, applicable to hybrid supercapacitors and batteries.

Originalspracheenglisch
Aufsatznummer4838
FachzeitschriftNature Communications
Jahrgang11
Ausgabenummer1
DOIs
PublikationsstatusVeröffentlicht - 2020

Schlagwörter

  • Electrochemistry
  • Energy Storage
  • Activated carbon
  • Iodine electrochemistry
  • SAXS
  • Raman spectroscopy

ASJC Scopus subject areas

  • Physik und Astronomie (insg.)
  • Chemie (insg.)
  • Biochemie, Genetik und Molekularbiologie (insg.)

Fields of Expertise

  • Advanced Materials Science

Treatment code (Nähere Zuordnung)

  • Basic - Fundamental (Grundlagenforschung)
  • Experimental

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