Simulation-Based Study on the Influence of Microporous Layer Gradient Porosity on the Performance of PEMFC

Proton exchange membrane fuel cell (PEMFC) has the advantages of high efficiency, high power density and easy recycling, which makes it significant in the future of energy transformation. However, PEMFC is also faced with the problem that the generated water will block the gas diffusion channels (GDL) and limit the current density so water management is crucial to improve the performance of PEMFC. In this paper, the microporous layer (MPL) of two kinds of pore structures were designed and investigated with simulation, and the maximum current density and maximum mole fraction of water are compared, indicating that the high porosity gradient can increase the capillary force to accelerate the outward diffusion of liquid water and prevent the condensation of gaseous water into liquid in the channel. Also, the study of the MPL with stepwise varying porosity which is closer to the actual design and manufacture of the MPL structure is carried out, and the conclusions are consistent with the study of the MPL with linearly varying porosity, indicating that it can better improve the performance of the MPL to make the porosity vary more uniformly, which should be considered when designing a MPL.