Three–Dimensional Polyacrylamide–Poly(Ethylene Glycol)/ Phosphoric Acid for High–Temperature Proton Exchange Membranes

Abstract

We report the feasibility of anhydrous polyacrylamide-poly(ethylene glycol)/phosphoric acid (PAAm-PEG/H3PO4) semi-interpenetrating network frameworks as high-temperature proton exchange membranes (PEMs). The PEMs are synthesized by imbibing H3PO4 aqueous solution into three-dimensional PAAm-PEG frameworks accompanied with a dehydration process. The electrical properties are optimized by adjusting synthesis conditions such as crosslinker, initiator and PEG dosages. Results show that the H3PO4 loading and therefore the proton conductivities of the PEMs are significantly enhanced at optimal synthesis conditions. The optimal anhydrous proton conductivity is as high as 0.18 S cm−1 at 180 °C. A fuel cell using a thick membrane as a PEM shows a peak power density of 635 mW cm−2 at 150 °C with O2 and H2 as the oxidant and fuel, respectively. The high proton conductivities at high temperatures in combination with the simple preparation, low cost, scalable hosts and proton conductors demonstrate the potential use of hydrogel materials in high-temperature PEM fuel cells.