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Helical peptide structure improves conductivity and stability of solid electrolytes

Nature Materials volume 23, pages 1539–1546 (2024)Cite this article

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A Publisher Correction to this article was published on 07 October 2024

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Abstract

Ion transport is essential to energy storage, cellular signalling and desalination. Polymers have been explored for decades as solid-state electrolytes by either adding salt to polar polymers or tethering ions to the backbone to create less flammable and more robust systems. New design paradigms are needed to advance the performance of solid polymer electrolytes beyond conventional systems. Here the role of a helical secondary structure is shown to greatly enhance the conductivity of solvent-free polymer electrolytes using cationic polypeptides with a mobile anion. Longer helices lead to higher conductivity, and random coil peptides show substantially lower conductivity. The macrodipole of the helix increases with peptide length, leading to larger dielectric constants. The hydrogen bonding of the helix also imparts thermal and electrochemical stability, while allowing for facile dissolution back to monomer in acid. Peptide polymer electrolytes present a promising platform for the design of next-generation ion-transporting materials.

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Fig. 1: Synthesis and conformation of helixes in the solid state.
Fig. 2: Temperature and thermal history effects on conductivity and stability.
Fig. 3: Role of increasing helix length on increased conductivity.
Fig. 4: Longer helices increase macrodipole, dielectric constant and conductivity.
Fig. 5: Liquid crystallinity at PPIL surfaces.
Fig. 6: Acid degradation of PPILs.

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Data availability

The authors declare that all data supporting the findings of this study are available within the paper and the Supplementary Information. The raw numbers for charts and graphs are available in the provided Source Data file whenever possible. Additional images are available from the corresponding author upon reasonable request. Source data are provided with this paper.

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Acknowledgements

This work is partially supported by the United States National Science Foundation (NSF CHE 17-09820 to J.C. and CHE 19-05097 to J.C. and P.V.B. for peptide synthesis, and DMR-1751291 to C.M.E. for polymerized ionic liquid physics). The work is also partially supported by the US Department of Energy, Office of Basic Energy Science, Division of Materials Sciences and Engineering under award #DE-SC0020858 (ionic conductivity and dielectric measurements). The authors acknowledge the facility and instrumental support from the Materials Research Laboratory, the SCS NMR Laboratory, Beckman Institute, University of Illinois Urbana-Champaign. Specifically, the Q-Tof Ultima mass spectrometer was purchased in part with a grant from the National Science Foundation, Division of Biological Infrastructure (DBI-0100085).

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Authors and Affiliations

  1. Department of Materials Science and Engineering, Materials Research Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, IL, USA

    Yingying Chen, Tianrui Xue, Chen Chen, Seongon Jang, Paul V. Braun, Jianjun Cheng & Christopher M. Evans

  2. School of Engineering, Westlake University, Hangzhou, China

    Jianjun Cheng

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Contributions

C.M.E conceived of using the helix to enhance conductivity, and Y.C and T.X. conceived of the polymer electrolyte design and synthesis. Solid 13C NMR was conducted by S.J. Dielectric spectroscopy was conducted by C.C. Y.C. and C.M.E. wrote the manuscript with contributions and critical feedback from T.X., C.C., S.J., J.C. and P.V.B. All authors discussed the results and commented on the manuscript.

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Correspondence to Christopher M. Evans.

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Chen, Y., Xue, T., Chen, C. et al. Helical peptide structure improves conductivity and stability of solid electrolytes. Nat. Mater. 23, 1539–1546 (2024). https://doi.org/10.1038/s41563-024-01966-1

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