Abstract
This paper investigated the mechanism of the hydrophilic MPL with carbon fiber (CF) to increase cell performance by comparing the cell performance and water distribution inside the MPL with different pore size and thickness. The results show that the hydrophilic thick CFMPL improves cell performance by preventing the increase of concentration overvoltage under high current density region. The direct observations by the freezing method and cryo- SEM shows that water is observed in pores of the CFMPL at the catalyst layer (CL) side, while there is no water in the thick CFMPL at the gas diffusion layer (GDL) side. This suggests that the hydrophilic thick CFMPL evaporates water in the CFMPL before the water reaches to the GDL side by the large pores and the adequate thickness of the CFMPL, resulting in better anti-flooding performance.