Transport Phenomena in Polymer Electrolyte Fuel Cells

Transport phenomena in polymer electrolyte fuel cells encompass the movement of reactant gases, protons and liquid water through the multilayered membrane electrode assembly. Optimising gas diffusion layers, catalyst layers and the polymer electrolyte membrane is essential to maintain efficient oxygen supply at the cathode, water removal and proton conduction across the membrane. Mass transport losses arise from insufficient reactant delivery, diffusion resistance within porous media and water flooding or dry‐out. Multiphase flow within the gas diffusion and catalyst layers governs liquid water production, distribution and removal, directly influencing local reactant concentrations and membrane hydration. Microstructural characteristics such as pore size distribution, tortuosity and ionomer morphology determine effective diffusivity, proton conductivity and capillary pressures. A multiscale understanding—from nanometre ionomer films to millimetre‐scale gas channels—is required to balance water management, minimise local transport resistances and sustain high power densities. Recent advances employ pore‐scale simulations, tomographic reconstructions and novel analytical frameworks to link microstructure to macroscopic performance, guiding the design of more durable and efficient fuel cell components.

Research from Nature Portfolio

Recent studies have elucidated the relation between catalyst layer microstructure and proton conductivity by generating synthetic three‐dimensional images of ionomer distributions. Through a combination of numerical simulation and adapted percolation theory, work has identified two limiting ionomer morphologies—thin films with high coverage and voluminous chunks—that govern proton transport pathways. An analytical model emerging from this research provides a unified relation linking film coverage, thickness and agglomerate architecture to effective conductivity over a wide range of compositions. This approach offers predictive guidance for ink formulation and processing, advocating well‐defined ionomer films on catalyst particles to optimise both conductivity and gas accessibility.

Transport Phenomena in Polymer Electrolyte Fuel Cells publication trend

The graph below shows the total number of articles in transport phenomena in polymer electrolyte fuel cells across all publications each year (not limited to Nature Index journals).

Technical terms

Ionomer: A proton‐conducting polymer phase within the catalyst layer that facilitates proton transport between reaction sites and the membrane.

Tortuosity: A measure of the convoluted pathways within porous media that impede effective gas and liquid diffusion compared with straight‐line distances.

Proton conductivity: The ability of the membrane or ionomer to transport protons, influenced by hydration level and microstructure.

Mass transport resistance: The hindrance to reactant or product movement within porous layers, often quantified as an additional voltage loss.

Two‐phase flow: Concurrent flow of gas and liquid phases within porous electrodes, critical for water management and reactant supply.

Triple‐phase boundary: The interfacial region where electrode, ionomer and gas phases meet, enabling simultaneous access to electrons, protons and reactants for electrochemical reaction.

References

1. Structure and conductivity of ionomer in PEM fuel cell catalyst layers: a model-based analysis. Scientific Reports (2023).
2. Tomographic Analysis and Modeling of Polymer Electrolyte Fuel Cell Unsupported Catalyst Layers. Journal of The Electrochemical Society (2018).
3. Heterogeneous pore-scale model analysis of micro-patterned PEMFC cathodes. Journal of Power Sources (2023).
4. Hybrid Lattice Boltzmann Agglomeration Method for Modeling Transport Phenomena in Polymer Electrolyte Membrane Fuel Cells. Journal of The Electrochemical Society (2021).
5. A Mixed Wettability Pore Size Distribution Based Mathematical Model for Analyzing Two-Phase Flow in Porous Electrodes. Journal of The Electrochemical Society (2017).