Preparation and properties of superprotonic conductor-based mixed matrix proton exchange membranes for energy conversion and storage

Abstract

The integration of crystalline metal-organic frameworks (MOFs) into polymer-based matrix to develop mixed matrix membranes (MMMs) is a rapidly growing research area, particularly in energy conversion and storage applications. Enhancing the loading capacity of MOFs in polymer matrices and improving interfacial compatibility are essential for preparing MMMs. This study involved the preparation of MMMs using a sulfonated microblock copolymer (SPP-3) with a high density of meta-ether oxygen bonds as the polymer matrix. The incorporation of the MOF-based superprotonic conductor UiO-66(SO₃H)₂ (USO) yielded the MMMs with up to 30 % loading and excellent dimensional stability, fabricated via conventional solvent evaporation. The ideal proton conductivity (PC) of the prepared MMMs achieved 165.0 mS cm⁻¹ at 80 °C, representing a 34.38 % increase relative to the initial membrane. The peak power density (PPD) of proton exchange membrane fuel cells (PEMFCs) reached 387.7 mW cm⁻². Notably, the positive correlation between the persistence length of hydrophobic structural domains in microblock copolymers and the effective contact area of crystalline MOFs was initially noted. This study proposed a new strategy for the fabrication of MMMs with high MOFs loading and investigated efficient interface compatibility.