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Thin membranes with Cu-ion crosslinking for high temperature polymer electrolyte membrane fuel cells

Nature Energy (2026)Cite this article

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Abstract

High-temperature polymer electrolyte membrane fuel cells offer inherent impurity tolerance and simplified thermal/water management. However, conventional phosphoric acid-doped membranes must be relatively thick (typically >50 μm) to counteract H3PO4-induced mechanical degradation, leading to ohmic losses that limit fuel cell performance. Here we report a 20-μm-thin, mechanically robust phosphoric acid-doped membrane incorporating dynamic Cu-ion crosslinking for high-power-density high-temperature polymer electrolyte membrane fuel cells. The dynamic Cu-polymer coordination establishes dynamic crosslinking networks that provide exceptional toughness and extensibility, alongside spontaneous self-healing capability. Simultaneously, the Cu ions improve H3PO4 retention and proton dissociation through electrostatic interactions and polarization of O–H bonds in H3PO4 molecules. The resulting thin membranes exhibit minimal ohmic resistance (0.06 Ω cm2) while maintaining low H2 crossover current density (0.95 mA cm−2). Fuel cells incorporating this membrane achieved a peak power density of 3.08 W cm−2 at 200 °C (H2/O2), with negligible degradation over 503 h at 1.0 A cm−2 and 160 °C.

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Fig. 1: Design of thin dynamic crosslinking PEMs for HT-PEMFCs.
The alternative text for this image may have been generated using AI.
Fig. 2: Formation and structure of Cu-ion crosslinking membrane.
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Fig. 3: Characterization of the dynamic Cu–N coordination.
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Fig. 4: Integrated mechanics, proton conduction and stability of dynamic Cu-ion crosslinking membranes.
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Fig. 5: Integrated mechanics, proton conduction and stability of dynamic Cu-ion crosslinking membranes.
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Fig. 6: Performance of single cells fed by dry H2-O2.
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Fig. 7: Durability of single cells based on 20-μm membranes.
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Acknowledgements

We would like to thank the National of Key R&D Program of China (number 2024YFE0207700 (S.L.)), the National Natural Science Foundation of China (number 22178012 (S.L.), U22A20419 (Y.X.), 22409011 (W. Li), 22572005 (Jin Zhang)). The programme was also sponsored by Beijing Nova Program (20220484140, (Jin Zhang)). We thank J. Xu and X. Wang from National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance Spectroscopy and Imaging, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences for providing assistance in NMR test and analysis. We also thank P. An and the 1W1B-XAFS Beamline of Beijing Synchrotron Radiation Facility for providing technical support and assistance in XAFS data collection. We acknowledge the facilities and the scientific and technical assistance of the Analysis and Testing Center, Beihang University.

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Authors and Affiliations

  1. Beijing Key Laboratory of Bio-inspired Energy Materials and Devices, School of Energy and Power Engineering, Beihang University, Beijing, China

    Zhenguo Zhang, Qi Zhang, Wen Li, Wen Liu, Jialin Zhang, Jin Zhang, Haining Wang, Yan Xiang & Shanfu Lu

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  1. Zhenguo Zhang
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Contributions

Z.Z. conceived the project, analysed the data and wrote the manuscript. Q.Z., Jialin Zhang and W. Li helped with data collection and assisted fuel cell measurements. W. Liu performed the DFT and MD calculations. Jin Zhang guided the research and helped with data collection. H.W. and Y.X. supervised and guided this work. S.L. proposed the concept, supervised the research and made final revisions to the manuscript.

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Correspondence to Jin Zhang, Yan Xiang or Shanfu Lu.

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Zhang, Z., Zhang, Q., Li, W. et al. Thin membranes with Cu-ion crosslinking for high temperature polymer electrolyte membrane fuel cells. Nat Energy (2026). https://doi.org/10.1038/s41560-026-02049-y

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