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Continuous transition from double-layer to Faradaic charge storage in confined electrolytes

Nature Energy volume 7, pages 222–228 (2022)Cite this article

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Abstract

The capacitance of the electrochemical interface has traditionally been separated into two distinct types: non-Faradaic electric double-layer capacitance, which involves charge induction, and Faradaic pseudocapacitance, which involves charge transfer. However, the electrochemical interface in most energy technologies is not planar but involves porous and layered materials that offer varying degrees of electrolyte confinement. We suggest that understanding electrosorption under confinement in porous and layered materials requires a more nuanced view of the capacitive mechanism than that at a planar interface. In particular, we consider the crucial role of the electrolyte confinement in these systems to reconcile different viewpoints on electrochemical capacitance. We propose that there is a continuum between double-layer capacitance and Faradaic intercalation that is dependent on the specific confinement microenvironment. We also discuss open questions regarding electrochemical capacitance in porous and layered materials and how these lead to opportunities for future energy technologies.

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Fig. 1: Overview of electrochemical interfaces with varying degrees of electrolyte confinement.
Fig. 2: Examples of potential-dependent effects in carbon EDLCs.
Fig. 3: Cation intercalation into the hydrated interlayer of birnessite.
Fig. 4: Influence of the number of graphene layers on Li+ charge storage.
Fig. 5: Unified approach to charge storage in nanoconfined environments.

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Acknowledgements

P.T.C., J.W., Y.G. and V.A. acknowledge support from the Fluid Interface Reactions, Structures and Transport (FIRST) Center, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences at Oak Ridge National Laboratory under contract no. DE-AC0500OR22725 with UT Battelle, LLC. S.F. acknowledges funding from the German Federal Ministry of Education and Research (BMBF) in the ‘NanoMatFutur’ program (grant no. 03XP0423). S.F. and P.S. acknowledge support from the Agence Nationale de la Recherche (Labex STORE-EX) and P.S. from the ERC Synergy Grant MoMa-Stor no. 951513.

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Authors and Affiliations

  1. Department of Materials Science & Engineering, North Carolina State University, Raleigh, NC, USA

    Simon Fleischmann & Veronica Augustyn

  2. Université Paul Sabatier, CIRIMAT UMR CNRS 5085, Toulouse, France

    Simon Fleischmann, Patrice Simon & Yury Gogotsi

  3. Helmholtz Institute Ulm (HIU), Ulm, Germany

    Simon Fleischmann

  4. Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany

    Simon Fleischmann

  5. Réseau sur le Stockage Electrochimique de l’Energie (RS2E), Amiens, France

    Simon Fleischmann & Patrice Simon

  6. INM—Leibniz Institute for New Materials, Saarbrücken, Germany

    Yuan Zhang & Volker Presser

  7. Saarland University, Saarbrücken, Germany

    Yuan Zhang & Volker Presser

  8. Department of Chemical & Environmental Engineering, University of California, Riverside, CA, USA

    Xuepeng Wang & Jianzhong Wu

  9. Department of Chemical and Biomolecular Engineering and Multiscale Modeling and Simulation Center, Vanderbilt University, Nashville, TN, USA

    Peter T. Cummings

  10. Department of Materials Science & Engineering, and A.J. Drexel Nanomaterials Institute, Drexel University, Philadelphia, PA, USA

    Yury Gogotsi

  11. Saarene—Saarland Center for Energy Materials and Sustainability, Saarbrücken, Germany

    Volker Presser

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Fleischmann, S., Zhang, Y., Wang, X. et al. Continuous transition from double-layer to Faradaic charge storage in confined electrolytes. Nat Energy 7, 222–228 (2022). https://doi.org/10.1038/s41560-022-00993-z

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