Poly(fluorenyl terphenyl piperidinium) with Sulfonated Side Chains for the Application of High-Temperature Proton Exchange Membranes
Yanbo Chen, Fei Xu, Jing Li, Yuyang Han, Junjie Qiao, Jie Liu, Yao Xu, Bencai Lin
Abstract
To produce proton exchange membranes (PEMs) with robust mechanical properties, poly(fluorenyl terphenyl piperidinium) (PFTP) with an aromatic backbone is synthesized. Sulfonated PFTP (SPFTP- x ) is obtained by introducing propanesulfonic acid onto PFTP as a side chain to enhance its phosphoric acid (PA) adsorption capacity and proton conductivity. Both the PFTP and SPFTP- x membranes exhibit good thermal, oxidization, and dimensional stabilities owing to their rigid ether-free aromatic backbones. Because of the introduction of propanesulfonic acid side chains, the SPFTP- x membranes show higher PA adsorption capacity and higher proton conductivity than the PFTP membrane. The PA doping content of the SPFTP- x membranes is more than 160% at room temperature, and their conductivity can be up to 109.0 mS cm –1 at 160 °C under anhydrous condition. Furthermore, a single cell assembled with SPFTP-50 exhibits a maximum power density of 280 mW cm –2 at 100 °C. These results indicate that SPFTP- x is a promising membrane material for applications in high-temperature proton exchange membrane fuel cells.