Proton exchange membrane water electrolysis (PEM-WE) is a clean method for hydrogen production and an important piece in the adoption of a hydrogen fuel economy. Proton exchange membranes require specific chemical and physical properties for efficient use in the PEM-WE system, and development of these membranes still presents a major challenge. Current industry standards such as Nafion^®, developed by DuPont, are costly, show high gas permeability, and are limited to operation below 90 °C.¹ Performance of a novel sulfonated poly(arylene ether) membrane, SA8, is investigated in this research. SA8 has shown a significantly higher glass transition temperature than Nafion, better mechanical properties, higher proton conductivity, and better chemical stability from various ex-situ tests and in-situ fuel testing. The multiphenylated backbone creates free volume around the sulfonic acid sites, which allows for greater water uptake with minimal swelling.² The presence of water is not only necessary for proton conductivity but is of particular importance in the water electrolyzer where the cell is fed liquid water, rather than operated at various humidities as in a fuel cell. In this research SA8 is found to successfully operate in a water electrolysis system at a temperature of 90 °C for over 120 hours. Polarization curves taken at 60 °C show operation of a 25 μm membrane at 1.8 V reaching a current density of 4 A cm^-2.

1. Ito, H., Maeda, T., Nakano, A. & Takenaka, H. International Journal of Hydrogen Energy (2011)
2. Lee, H. F., Huang, Y.C., Wang, P.H., Lee, C.C., Hung, Y.S., Gopal, R., Holdcroft, S., Huang, W.Y. Mater. Today Commun. 3, 114–121 (2015).