Degradation Studies of Single Cell and Short Stack for High Temperature Proton Exchange Membrane Fuel Cells Based on PBI/H3PO4 Membrane

Abstract

AbstractDurability is a premise of extensive application for high‐temperature proton exchange membrane fuel cells (HT‐PEMFCs) based on H3PO4 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 H3PO4 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.