Poly(arylene piperidine)s with phosphoric acid doping as high temperature polymer electrolyte membrane for durable, high-performance fuel cells

Abstract

The properties of high temperature polymer electrolyte membranes (HT-PEMs) are determined directly by the polymer matrix with phosphoric acid (PA) doping. Here, new polymer materials based on poly (arylene piperidine)s (PAPs) are prepared by one-step polymerization as PA absorbing matrix for HT-PEM fuel cells (HT-PEMFCs) application. The PAPs show excellent thermal stability and high glass transition temperature. Among PAPs, PA doped poly (N-methyl-piperidine-co-p-terphenyl) (PPT/PA) shows a high proton conductivity of 96.0 mS cm−1 at 180 °C without humidification and an excellent tensile strength of 12 MPa, which is much better than that of PA doped commercial poly [2,2’-(p-oxydiphenylene)-5,5′-benzimidazole] (OPBI/PA). The enhancement on conductivity of PPT/PA is attributed to the formation of micro-phase separation. A single cell based on PPT/PA membrane presents outstanding performance with a maximum power density of 1220.2 mW cm−2 with H2/O2 feeding under 0.15 MPa backpressure in cathode at 180 °C, which is 1.85 times of that with OPBI/PA membrane (660.8 mW cm−2). Furthermore, a H2/air single cell with PPT/PA shows excellent stability at a constant current density of 120 mAcm−2 and 150 °C for 1600 h. This work indicates PAPs (especially, PPT) are a promising PA doping polymer matrix for high temperature polymer electrolyte membrane fuel cells application.