Degradation Studies of Single Cell and Short Stack for High Temperature Proton Exchange Membrane Fuel Cells Based on PBI/H 3 PO 4 Membrane

Durability is a premise of extensive application for high‐temperature proton exchange membrane fuel cells (HT‐PEMFCs) based on H 3 PO 4 doped polybenzimidazole membrane, but is far unsatisfactory. In this work, using our home‐made electrodes, a single cell with a start‐stop operation for 1900 h and a short stack with a continuous operation for 1344 h are separately conducted at 0.2 A cm −2 with hydrogen‐air feed. After 1900 h operation, an average degradation rate of 59.5 μV h −1 is obtained. Combined scanning electron microscope with energy dispersive spectrometer, transmission electron microscope, and electrochemical methods, the start‐stop operation cause more serious H 3 PO 4 loss, cobalt element leaching, and platinum particles agglomeration, which produces a decreased ion conductivity and a big active polarization loss. In short stack test, we find electrode consistency is more important. An inferior cell enables a rapid failure due to almost complete acid loss in the membrane. The bigger polarization loss and more joule heat at the inferior electrode from a lower ionic and electrical conductivity further make acid loss aggravated, and it is a vicious circle. Despite a big gaps with life requirement, we believe our work will give a guidance for the design of high stable HT‐PEMFCs.