Sulfonated Microporous\nPolyxanthene Binder for High-Temperature\nHydrogen Fuel Cells

High-temperature\nproton exchange membrane fuel cells\nbased on phosphoric\nacid-doped polybenzimidazole (PBI) materials face challenges of low\npower output and low Pt utilization due to the lack of suitable electrode\nbinders. We have developed a sulfonated microporous polymer material\n(namely, SPX, i.e., sulfonated polyxanthene) with excellent chemical\nstability, to be used as the electrode binder. The rigid and contorted\npolymer structure of SPX reduces the adsorption of the ionomer on\nthe Pt catalyst surface, prevents phosphoric acid loss, and promotes\nthe rapid transport of reactant gases and water molecules within the\ncatalyst layer. The cell performance is thereby significantly improved,\nwith a Pt utilization reaching 42.51%, and a peak power density approaching\n805 mW cm<sup>–2</sup> at 180 °C, surpassing the performance\nof cells using PBI as a binder.