Proton exchange membrane based on interpenetrating polymer network structure for excellent cell performance and chemical stability

Abstract

Chemical stability and proton conductivity are the most critical factors for proton exchange membranes (PEMs). Here, we designed and prepared a co-polymer containing radical scavenger groups and imidazole groups. The membrane's acid-base crosslinking and interpenetrating network structure offer the PEM excellent dimensional stability and gas permeation inhibition properties. The continuous acid-base pairs and imidazole groups, which have high water retention, effectively improve the proton conductivity and reduce the PEM's gas permeability. Hence, a membrane electrode assembly based on as-prepared composite membranes exhibits higher single-cell performance and lower impedance than other membranes used for comparison. In addition, the introduction of hindered amine scavenger groups effectively eliminates the free radicals generated in the process of the electrochemical reaction. Both in-situ and ex-situ stability experiments show that the prepared composite membrane has excellent chemical stability. Morphological changes according to degradation level are also systematically analyzed. This paper shows that the introduction of imidazole and HA groups in the PFSA matrix membrane is effective for improving fuel cell performance and lifetime and for constructing continuous proton transport networks and interpenetrating network structures, making this a promising approach for achieving excellent proton conductivity and chemical stability in PEMs.