Failure of cathode gas diffusion layer in 1 kW fuel cell stack under new European driving cycle

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One of the main limitations of the proton exchange membrane fuel cells’ lifetime is the gradual diminishment of output power for the absence of a robust gas diffusion layer. Therefore, it is necessary to understand the decay process of the gas diffusion layer in actual working conditions. This study aims to investigate how the operation of automobile to push the degradation of gas diffusion layer by conducting a 1000 h in-situ durability test using a 1 kW stack under a simulative operation condition - New European Driving Cycle. The results demonstrate that the degradation of gas diffusion layer makes about 20% contribution to the decreased power density of proton exchange membrane fuel cells stack. The support failure caused by the collapse of structure and degradation of carbon fiber is the main reason for the attenuation of gas diffusion layer. Moreover, repeating operation of high voltage causes the structural collapse and the loss of polytetrafluoroethylene, which both change the ratio of hydrophilic surface to hydrophobic. Deeper analysis shows that the mass transport resistance of the degraded gas diffusion layer is almost three times than that of the fresh layer under the same current density due to decreased effective pore volume. Therefore, this work provides new ideas for the durability investigation of stack and gas diffusion layer.