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Disentangling water, ion and polymer dynamics in an anion exchange membrane

Nature Materials volume 21, pages 555–563 (2022)Cite this article

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Abstract

Semipermeable polymeric anion exchange membranes are essential for separation, filtration and energy conversion technologies including reverse electrodialysis systems that produce energy from salinity gradients, fuel cells to generate electrical power from the electrochemical reaction between hydrogen and oxygen, and water electrolyser systems that provide H2 fuel. Anion exchange membrane fuel cells and anion exchange membrane water electrolysers rely on the membrane to transport OH− ions between the cathode and anode in a process that involves cooperative interactions with H2O molecules and polymer dynamics. Understanding and controlling the interactions between the relaxation and diffusional processes pose a main scientific and critical membrane design challenge. Here quasi-elastic neutron scattering is applied over a wide range of timescales (100–103 ps) to disentangle the water, polymer relaxation and OH− diffusional dynamics in commercially available anion exchange membranes (Fumatech FAD-55) designed for selective anion transport across different technology platforms, using the concept of serial decoupling of relaxation and diffusional processes to analyse the data. Preliminary data are also reported for a laboratory-prepared anion exchange membrane especially designed for fuel cell applications.

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Fig. 1: Schematic illustration of AEM-FC and the FAD-55 AEM in relation to measurement protocol.
Fig. 2: EFWS intensity and m.s.d. data for FAD-55 membrane.
Fig. 3: Analysis of QENS associated with different dynamical processes; data for FAD-55 membrane.
Fig. 4: Intermediate scattering function to investigate relaxation dynamics as a function of their timescale; data for FAD-55 membrane.
Fig. 5: From dynamics parameters to AEM performance; data for FAD-55 membrane.

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All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Information. Additional data related to this paper may be requested from the authors. Source data are provided with this paper.

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Acknowledgements

In loving memory of Prof. Paul F. McMillan, a brilliant scientist and mentor, who not only inspired this work, but also his many colleagues throughout a long and proud career. F.F. acknowledges EPSRC for funding (grant EP/V057863/1). We thank the neutron scattering facilities at ILL (Grenoble, France), ISIS (Didcot, UK) and NIST (USA) for the award of beamtime necessary to carry out these experiments. We are grateful to ISIS and ILL for neutron beamtime (https://doi.org/10.5286/ISIS.E.RB1920608, https://doi.org/10.5286/ISIS.E.RB2090038-1 and https://doi.org/10.5291/ILL-DATA.9-11-1916). We also thank the Science and Technology Facilities Council for the use of the Nano-inXider instrument in the Materials Characterisation Laboratory. Access to the HFBS was provided by the Center for High-Resolution Neutron Scattering, a partnership between NIST and the National Science Foundation under agreement number DMR-2010792. Certain commercial equipment, instruments or materials are identified in this paper in order to specify the experimental procedure adequately. Such identification is not intended to imply recommendation or endorsement by NIST. This project received funding from the EU Graphene Flagship under Horizon 2020 Research and Innovation programme grant agreement no. 881603-GrapheneCore3 and from the Engineering and Physical Sciences Research Council Materials Research Hub for Energy Conversion, Capture, and Storage (M-RHEX) EP/R023581/1. F.F. acknowledges EPSRC for funding (grant EP/V057863/1). A.J.C. thanks the Society of Chemical Industry and the Ramsay Memorial Trust for support. Degradation studies performed at Surrey University were funded by Engineering and Physical Sciences Research Council grants EP/M022749/1 and EP/T009233/1.

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Author notes

  1. Deceased: Paul F. McMillan.

Authors and Affiliations

  1. Department of Chemistry, Christopher Ingold Laboratory, University College London, London, UK

    Fabrizia Foglia, Adam J. Clancy & Paul F. McMillan

  2. Université Grenoble Alpes, CNRS, CEA, IRIG-SyMMES, Grenoble, France

    Quentin Berrod, Gérard Gebel & Sandrine Lyonnard

  3. Electrochemical Innovation Lab, Department of Chemical Engineering, University College London, London, UK

    Keenan Smith, Thomas S. Miller, Daniel J. L. Brett & Paul R. Shearing

  4. ISIS Neutron and Muon Source, Science & Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Chilton, UK

    Victoria García Sakai & Najet Mahmoudi

  5. Institut Laue Langevin, Grenoble, France

    Markus Appel

  6. Laboratoire Léon Brillouin (CEA-CNRS), Université Paris-Saclay, CEA Saclay, Gif-sur-Yvette Cedex, France

    Jean-Marc Zanotti

  7. NIST Center for Neutron Research (NCNR), National Institute of Standards and Technology, Gaithersburg, MD, USA

    Madhusudan Tyagi

  8. Department of Materials Science and Engineering, University of Maryland, College Park, MD, USA

    Madhusudan Tyagi

  9. Department of Chemistry, University of Surrey, Guildford, UK

    John R. Varcoe & Arun Prakash Periasamy

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Contributions

The study was initiated as a collaboration between the Commissariat à l’énergie atomique et aux énergies alternatives and University College London at a meeting between P.R.S., F.F., P.F.M., S.L., G.G., Q.B. and J.-M.Z., following discussions with D.J.L.B. and T.S.M. Neutron scattering experiments were initiated and directed by F.F. and S.L. in collaboration with V.G.S., Q.B., J.-M.Z., M.A. and M.T. at neutron beamline facilities. A.J.C. and K.S. also participated in neutron scattering experiments; K.S. carried out ionic conductivity experiments under supervision from T.S.M., D.J.L.B. and P.R.S.; A.J.C. provided Fourier transform infrared spectroscopy and TGA data; and N.M. obtained essential small- and wide-angle X-ray scattering and small-angle neutron scattering data. F.F. and P.F.M. worked closely with S.L. and Q.B. to interpret the neutron scattering results. Sample degradation, IEC determinations and Raman spectroscopy experiments were initiated and carried out by J.R.V. and A.P.P. All authors read, edited, commented on and fully contributed to developing the study and this manuscript.

Corresponding authors

Correspondence to Fabrizia Foglia or Sandrine Lyonnard.

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Nature Materials thanks Dario Dekel, Naresh Osti and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–23, Texts 1–3 and Tables 1–9.

Source data

Source Data Fig. 1

Raw data for Raman spectra (Fig. 1h).

Source Data Fig. 2

Raw data for EFWS acquired at Eres = 1 μeV (Fig. 2c).

Source Data Fig. 3

Data reported in Fig. 3m.

Source Data Fig. 5

Data reported in Fig. 5c,d.

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Foglia, F., Berrod, Q., Clancy, A.J. et al. Disentangling water, ion and polymer dynamics in an anion exchange membrane. Nat. Mater. 21, 555–563 (2022). https://doi.org/10.1038/s41563-022-01197-2

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