Evaluation of thermal cycling on durability and PA loss in high temperature PEM fuel cells

Abstract

This study investigates the durability of high temperature proton exchange membrane fuel cells (HT-PEMFCs) under various thermal cycling conditions: temperature changes between 140 °C and 180 °C (TC1), simulated 50 °C to 160 °C start–stop cycles (TC2), and 50 °C to 160 °C start–stop cycles under open circuit voltage (TC3). Accelerated stress tests and electrochemical evaluations were used to study voltage degradation, shifts in polarization curves, electrochemical impedance spectroscopy (EIS), and phosphoric acid (PA) leaching. The findings indicate escalating voltage degradation rates, peaking at 75.6 μV h⁻¹ in TC3, significantly higher than the 14.2 μV h⁻¹ observed at a steady 160 °C. Additionally, a decline in polarization curves and increased PA leaching were noted, with the most significant escalation in TC3, where it reached 36.1 ng cm⁻² h⁻¹, compared to 6.9 ng cm⁻² h⁻¹ in TC1 and 8.3 ng cm⁻² h⁻¹ under constant temperature. Furthermore, EIS analysis indicated substantial increases in charge transfer and ohmic resistance under the various thermal cycling tests. These results underscore the crucial need for improved thermal management strategies in HT-PEMFCs to enhance their durability under fluctuating thermal conditions.

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