Persistent and Reversible Solid Iodine Electrodeposition in Nanoporous Carbons

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 in nanoporous carbons electrochemical oxidation of iodide 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 modelling, 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.<br>

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Persistent and Reversible Solid Iodine Electrodeposition in Nanoporous Carbons

10.26434/chemrxiv.12173214.v1 ◽

2020 ◽

Author(s):

Christian Prehal ◽

Harald Fitzek ◽

Gerald Kothleitner ◽

Volker Presser ◽

Bernhard Gollas ◽

...

Keyword(s):

Raman Spectroscopy ◽

Volume Fraction ◽

Stochastic Modelling ◽

Redox Activity ◽

Potential Candidate ◽

Nanoporous Carbons ◽

In Situ Raman Spectroscopy ◽

Hybrid Supercapacitors ◽

In Situ Raman

Aqueous iodine based electrochemical energy storage is considered a potential candidate to improve sustainability and electrochemical 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 in nanoporous carbons electrochemical oxidation of iodide 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 spectroscopy confirms the formation of triiodide and pentaiodide during iodide oxidation. Besides polyiodides, remarkable amounts of solid iodine are deposited in the carbon nanopores, as detected by in situ SAXS/WAXS. Combined with stochastic modelling, 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.<br>

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Persistent and reversible solid iodine electrodeposition in nanoporous carbons

Nature Communications ◽

10.1038/s41467-020-18610-6 ◽

2020 ◽

Vol 11 (1) ◽

Cited By ~ 1

Author(s):

Christian Prehal ◽

Harald Fitzek ◽

Gerald Kothleitner ◽

Volker Presser ◽

Bernhard Gollas ◽

...

Keyword(s):

Volume Fraction ◽

Lattice Models ◽

Redox Activity ◽

Potential Candidate ◽

Nanoporous Carbons ◽

In Situ Raman Spectroscopy ◽

Hybrid Supercapacitors ◽

In Situ Raman ◽

And Performance

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.

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New insights on electrochemical hydrogen storage in nanoporous carbons by in situ Raman spectroscopy

Carbon ◽

10.1016/j.carbon.2013.12.042 ◽

2014 ◽

Vol 69 ◽

pp. 401-408 ◽

Cited By ~ 30

Author(s):

S. Leyva-García ◽

E. Morallón ◽

D. Cazorla-Amorós ◽

F. Béguin ◽

D. Lozano-Castelló

Keyword(s):

Raman Spectroscopy ◽

Hydrogen Storage ◽

Nanoporous Carbons ◽

In Situ Raman Spectroscopy ◽

In Situ Raman ◽

Electrochemical Hydrogen Storage

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“In-Situ Raman Spectroscopy of Electronic Processes in Fullerene Thin Films

MRS Proceedings ◽

10.1557/proc-725-p10.8 ◽

2002 ◽

Vol 725 ◽

Author(s):

S.B. Phelan ◽

B.S. O'Connell ◽

G. Farrell ◽

G. Chambers ◽

H.J. Byrne

Keyword(s):

Thin Film ◽

Indium Tin Oxide ◽

Low Temperatures ◽

In Situ Raman Spectroscopy ◽

State Reduction ◽

In Situ Raman ◽

Linear Behavior ◽

Current Voltage ◽

Solid State Reduction

AbstractThe current voltage characteristics of C60 thin film sandwich structures fabricated by vacuum deposition on indium tin oxide (ITO) with an aluminium top electrode are presented and discussed. A strongly non-linear behavior and a sharp increase in the device conductivity was observed at relatively low voltages (∼2V), at both room and low temperatures (20K). At room temperature the system is seen to collapse, and in situ Raman measurements indicate a solid state reduction of the fullerene thin film to form a polymeric state. The high conductivity state was seen to be stable at elevated voltages and low temperatures. This state is seen to be reversible with the application of high voltages. At these high voltages the C60 film was seen to sporadically emit white light at randomly localized points analogous to the much documented Electroluminescence in single crystals.

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