Effect of LiCl content on pore structure of catalyst layer and cell performance in high temperature polymer electrolyte membrane fuel cell

GDEs (gas diffusion electrodes) fabricated with catalyst layer, supporting layer and GDL (gas diffusion layer) are prepared for high temperature polymer electrolyte membrane fuel cell. A supporting layer consisting of different amount of PTFE (polytetrafluorethylene)-bonded carbon black from 0.0 g to 0.2 g is coated onto GDL to prevent Pt loss into GDL and to enhance the intimate contact between catalyst layer and GDL. Various catalyst layers are prepared by different LiCl content in PBI (polybenzimidazole) solution and coated directly on the top of optimized supporting layer. After preparing GDE, LiCl is leached out of the catalyst layer and the pore structure of GDE left behind the leaching is investigated with LiCl content. The N2 adsorption isotherm indicates that leaching of LiCl from catalyst layer leaves the pores behind and the BET surface area is increased with LiCl content. It is seen that the LiCl content significantly affects the dispersion of Pt nanoparticles in PBI: that is, too low LiCl content leads to non-uniform dispersion of Pt nanoparticles, resulting in poor cell performance. An appropriate amount of LiCl would lead to better cell performance.