Effect of High-Temperature Operation on Voltage Cycling Induced PEMFC Degradation: From Automotive Customer Drive Cycles to an Accelerated Stress Test

Abstract Degradation of the Pt catalyst during load cycling constitutes a major durability issue for proton exchange membrane fuel cells (PEMFCs) in automotive applications. In this study commercial 5 cm2 electrodes were exposed to 20 k voltage cycles between 0.6 – 0.9 VRHE at temperatures ranging from 75 to 120°C. The electrochemical surface area (ECSA), the roughness factor (rf), and the oxygen transport resistance were investigated over the course of the test. The degradation was mainly governed by Pt agglomeration and was accelerated with increasing temperature. Interestingly, operation at high temperature (120°C and 30% RH) caused the same ECSA loss as at standard conditions (90°C and 90% RH), suggesting that when maintaining dry conditions high-temperature operation is not critical for the durability of the catalyst material. The experimental results were used to validate an existing 0D catalyst degradation model, which was then applied to an automotive customer drive cycle. The calculated degradation over the whole automotive lifetime (excluding startup shutdown and idle events) equals 20k voltage cycles (0.6 – 0.9 V, 10 s hold time) at 90°C and 30% RH, which provides a guideline for the assessment of the suitability of novel catalyst materials for automotive applications.