Constructing High-Performance Proton Transport Channels in High-Temperature Proton Exchange Membranes by Introducing Triazole Groups

Recently, constructing proton transport channels has been considered an effective method to improve proton conductivity of high-temperature proton exchange membranes (PEM) with low phosphoric acid (PA)-doping levels. To construct proton transport channels, a metal–organic framework (MOF) is introduced into a polymer matrix. However, the MOF has poor compatibility with the polymer matrix as an inorganic substance. In this study, organic triazole-grafted poly(vinylbenzyl chloride) is synthesized and introduced into a cross-linked OPBI membrane to construct proton transport channels. Scanning electron microscopy (SEM) images show a homogeneous microstructure. Furthermore, proton transport channels are constructed in the membrane by introducing numerous triazole groups. The cross-linked OPBI has twice the proton conductivity of the linear OPBI, even with a low PA-doping level. All cross-linked membranes with a triazole group outperform OPBI membranes in terms of mechanical properties. The maximum power density of a single-cell test reaches 563 mW cm–2 at 160 °C under H2/O2, and it can be maintained for 500 h under a constant load of current discharge without manifest voltage degradation. These impressive results indicate that the moderately cross-linked membrane with triazole groups is one of the potential materials for PEM applications.