Membrane Durability in Proton Exchange Fuel Cells

Proton exchange fuel cells rely on a thin polymer membrane to conduct protons from anode to cathode while preserving separation of reactant gases. The durability of this membrane underpins overall cell lifetime and reliability. Mechanical stresses from pressure variations and humidity cycles can induce cracks, pinholes and swelling, while chemical attack by free radicals generated during operation leads to chain scission and loss of ion exchange groups. Thermal cycling and start–stop transients exacerbate degradation through local hygrothermal stresses and reactive oxygen species. Membrane thinning and loss of proton conductivity manifest as voltage decay and eventual cell failure. Advances in membrane materials—including reinforced composites and radical scavengers—combined with system-level control of humidity and pressure have been directed at prolonging service life. Imaging and multiscale modelling now permit real-time visualisation of degradation processes and prediction of durability under varying operating regimes. As fuel cell technologies expand into transport and stationary power, understanding and mitigating membrane failure pathways is critical to commercial viability and the global hydrogen economy.

Research from Nature Portfolio

Operando four-dimensional X-ray computed tomography has enabled direct, time-resolved visualisation of membrane and catalyst layer changes during accelerated stress tests. These studies reveal the evolution of cathode catalyst layer cracks, membrane swelling and delamination, and correlate morphological shifts with local water distribution and carbon support loss. Such insight clarifies the interplay between mechanical deformation and electrochemical ageing, highlighting regions most susceptible to performance decline. Investigations into the Fenton reaction mechanism for hydrated PFSA membranes have redefined our understanding of chemical degradation pathways. Contrary to earlier assumptions of hydroxyl radical involvement, density functional theory studies indicate direct C–S bond dissociation driven by hydrogen peroxide coordination to iron complexes. The findings explain side-chain scission and acid group formation, offering a molecular basis for improved membrane formulations and targeted scavenger strategies.

Membrane Durability in Proton Exchange Fuel Cells publication trend

The graph below shows the total number of articles in membrane durability in proton exchange fuel cells across all publications each year (not limited to Nature Index journals).

Technical terms

Proton exchange membrane (PEM): A polymer electrolyte layer that conducts protons while preventing the mixing of fuel and oxidant gases.

Perfluorosulfonic acid (PFSA): A class of fluorinated polymers used in PEMs, characterised by sulfonic acid functional groups for proton conduction.

Fenton reaction: A redox process involving hydrogen peroxide and iron ions that generates oxidative species capable of degrading organic materials.

Membrane electrode assembly (MEA): The integrated unit in a fuel cell comprising the proton exchange membrane, catalyst layers and gas diffusion layers.

References

1. Four-dimensional joint visualization of electrode degradation and liquid water distribution inside operating polymer electrolyte fuel cells. Scientific Reports (2019).
2. Fenton reaction mechanism generating no OH radicals in Nafion membrane decomposition. Scientific Reports (2020).
3. Main degradation mechanisms of polymer electrolyte membrane fuel cell stacks – Mechanisms, influencing factors, consequences, and mitigation strategies. International Journal of Hydrogen Energy (2024).
4. Electrochemical impedance spectroscopy of PEM fuel cells at low hydrogen partial pressures: efficient cell tests for mass production. Industrial Chemistry and Materials (2024).
5. A Review of the Transition Region of Membrane Electrode Assembly of Proton Exchange Membrane Fuel Cells: Design, Degradation, and Mitigation. Membranes (2022).