Porous organic polymer with high-density phosphoric acid groups as filler for hybrid proton exchange membranes

Developing sulfonated poly (ether ether ketone) (SPEEK)-based proton exchange membrane with both high proton conductivity and robust mechanical stability is desired for proton exchange membrane fuel cell (PEMFC). Here, a type of phosphoric acid porous organic polymer (PAPOP) with high‐density phosphoric acid (-PO3H2) groups and microporous structure was synthesized and incorporated into SPEEK matrix. The porous skeleton bonding -PO3H2 groups of PAPOP reduced the proton transfer activation energy by providing additional proton conduction pathways. The rigid backbone of PAPOP and its good compatibility with SPEEK increased the mechanical strength of the membrane. The hybrid membrane achieves greatly enhanced proton conductivity up to 417.0 mS cm−1 (80 °C, 100% RH) and high tensile strength of 120.6 MPa. The maximum power density of fuel cell with the hybrid membrane exhibits two times increase compared with the control membrane.