Side chain sulfonic acid polymers with intrinsic pores in the main chain as proton exchange membranes for fuel cells and redox flow battery

The high proton conductivity, good dimensional stability and acceptable mechanical properties of proton exchange membranes (PEMs) are important indicators for the practical application of membrane materials in clean energy storage and conversion systems. In this work, we prepared SPDI-x, a membrane material with rigid and twisted main chains and intrinsic channels by an efficient and simple route. It combined a rigid and twisted skeleton with a flexible sulfonic acid side chain to achieve high conductivity and a limited swelling rate. The conductivity of SPDI-x at 80 °C was 233 mS cm−1, and the swelling rate was lower than 14%. SPDI-x demonstrated higher coulomb efficiency, energy efficiency and voltage efficiency than commercial Nafion212 in redox flow battery. In addition, it had more stable long-term cycle performance under the same test conditions. The H2–O2 fuel cell has a maximum peak power density of 823 mW cm−2, which is also higher than the battery performance of commercial PEMs under the same test conditions. The high mass transfer performance and good battery performance of SPDI-x provide a new idea for the structural design of high-performance proton exchange membranes.