Boosting the power density of the H₃PO₄/polybenzimidazole high-temperature proton exchange membrane fuel cell to >1.2 W cm^-2 via the deposition of acid-based polymer layers on the catalyst layers

The high-temperature proton exchange membrane fuel cells (HT-PEMFCs) based on H3PO4/polybenzimidazole (PBI) membrane have drawn much attention in recent years. However, the power density of the H3PO4/PBI based membrane electrode assembly (MEA) is still much lower than that of the common perfluorosulfonate membranes based low-temperature proton exchange membrane fuel cells (LT-PEMFCs). Regulation and control of redistribution of H3PO4 in the MEA is a most important issue for the power density improvement of H3PO4/PBI based MEA. Herein, a MEA with new structure is proposed, in which a layer of PBI without H3PO4 doping (referred to as the acid-based polymer layers or APL) is deposited on the catalyst layers. With the application of APL, the peak power density of the H3PO4/PBI based MEA is 902 mW cm(-2) in H-2/air, and 1.289 W cm(-2) in H-2/O-2 at 180 degrees C, which is the highest performance for H3PO4/PBI based HT-PEMFC reported in the literature. The results shows that the APL could effectively promote the reasonable redistribution of H3PO4 along the cross section in the MEA, construct more three phase boundaries (TPBs), enhance the electrochemical active surface area (ECSA), thus boosting the performance of H3PO4/PBI based HT-PEMFC.