What is it about?
In a Polymer Electrolyte Membrane Fuel Cell (PEMFC), the catalyst layer—made of platinum (Pt)—is responsible for converting hydrogen and oxygen into power. While we often measure the "average" health of this layer, this study reveals a massive heterogeneity (unevenness) in how this catalyst wears out. Using a specialized sixteen-segmented membrane electrode assembly (MEA), the researchers tracked the "Effective Platinum Surface Area" (EPSA) across different zones of a single working cell. They subjected the cell to Accelerated Stress Tests (ASTs) to simulate years of heavy use. The results were stark: The Outlet Penalty: The segments near the gas outlet showed a 21% higher loss in platinum surface area compared to the inlet segments. Resistance Spike: The polarization resistance—a measure of how hard it is for electricity to flow—was 14% higher at the outlet. Corrosive Micro-climates: The study linked these failures to local fluctuations in relative humidity, temperature, and pressure that occur naturally as gases travel across the cell. By comparing a segmented cell to a standard "non-segmented" one, the authors demonstrated that local degradation is far more severe than previously thought, as standard tests often "mask" these dying zones by averaging them with healthier ones.
Featured Image
Photo by Maximalfocus on Unsplash
Why is it important?
Platinum is the single most expensive component of a fuel cell. If 10% of the cell's area degrades twice as fast as the rest, the entire stack may need to be replaced prematurely, wasting the remaining 90% of the healthy catalyst. This research provides the industry with: Spatial Reliability Data: It proves that "one size fits all" durability models are inaccurate. Designers must account for the harsher chemical environment at the cell's outlet. Improved Lifespan Predictions: By identifying that the platinum dissolution rate is 50% higher at the outlet, manufacturers can implement "gradient" designs—perhaps using more platinum or different cooling strategies at the outlet to balance the decay. Diagnostic Precision: The use of Cyclic Voltammetry on individual segments allows for a "biopsy" of the cell's health without destroying it, providing a blueprint for real-time health monitoring in commercial vehicles.
Perspectives
This study highlights a fundamental "design paradox" in green energy: we are building high-tech systems using materials that are inherently sensitive to their own byproducts. In a PEMFC, the water produced at the cathode increases humidity as it moves toward the outlet. This study elegantly demonstrates that this necessary byproduct becomes a "slow poison" for the platinum catalyst. The finding that kinetic losses and Pt dissolution are spatially coupled suggests that the future of fuel cell engineering isn't just about better materials, but better architectures. We can no longer treat the MEA as a uniform sheet of paper. Instead, we must treat it as a dynamic environment where the "weather" at the inlet is different from the "weather" at the outlet. Dhanushkodi and the team have provided the empirical evidence needed to move toward asymmetric cell design. By quantifying the "Outlet Penalty," they have set the stage for a new generation of fuel cells that are reinforced where they are most vulnerable, potentially doubling the operational life of hydrogen-powered trucks and ships.
Dr. Shankar Raman Dhanushkodi
University of British Columbia
Read the Original
This page is a summary of: PEMFC Durability: Spatially Resolved Pt Dissolution in a Single Cell, Journal of The Electrochemical Society, January 2014, The Electrochemical Society,
DOI: 10.1149/2.1031412jes.
You can read the full text:
Contributors
The following have contributed to this page
