(Invited) Progress in Nafion™ Membrane Development for Proton Exchange Membrane Water Electrolyzers

Abstract

Proton exchange membrane water electrolyzers (PEMWE) have received significant recent attention in order to address the burgeoning need for low/zero-carbon sources of hydrogen at scale. PEMWE devices are an attractive source of “green” hydrogen due to their relatively compact size, scalable construction, high efficiency, and proven durability. They also integrate well with intermittent electricity sources and can deliver elevated hydrogen outlet pressures to reduce parasitic efficiency losses associated with hydrogen compression.1 Membranes made from Nafion™ perfluorosulfonic acid (PFSA) polymer have been the leader in PEMWE device application for decades, due to their high proton conductivity and chemical durability in the hot, acidic PEMWE environment. Traditional Nafion™ membranes in this application, however, comprise thick films (>100 µm) where ohmic-driven voltage losses due to proton transport resistance are high.To maximize the electrical efficiency and hydrogen production of PEMWE applications, and help drive hydrogen costs below $2/kg, new membranes – specifically engineered for low proton transport resistance and high durability in a PEMWE environment – are required. A multigenerational plan has been established to improve the performance of Nafion™ membranes while maintaining their best-in-class durability. One major contributor to membrane improvement is a reduced proton transport resistance inherent in thinner membranes. However, as membranes become thinner, they invite higher gas crossover, especially in a differential pressure environment. Novel mitigation strategies are required to ensure safe operation and long lifetimes of the thinnest membranes in advanced PEMWE membrane concepts.2-3 In this presentation, an overview of the activities and strategic developments within Nafion™ membranes for water electrolyzers will be summarized. The multigenerational product development program will be discussed, highlighting the significant contribution possible from Nafion™ membrane development to green hydrogen proliferation. Ayers, K.; Danilovic, N.; Ouimet, R.; Carmo, M.; Pivovar, B.; Bornstein, M., Perspectives on Low-Temperature Electrolysis and Potential for Renewable Hydrogen at Scale. Annual Review of Chemical and Biomolecular Engineering 2019, 10 (1), 219-239.Klose, C.; Trinke, P.; Böhm, T.; Bensmann, B.; Vierrath, S.; Hanke-Rauschenbach, R.; Thiele, S., Membrane Interlayer with Pt Recombination Particles for Reduction of the Anodic Hydrogen Content in PEM Water Electrolysis. J. Electrochem. Soc. 2018, 165 (16), F1271-F1277.Baker, A. M.; Babu, S. K.; Mukundan, R.; Advani, S. G.; Prasad, A. K.; Spernjak, D.; Borup, R. L., Cerium Ion Mobility and Diffusivity Rates in Perfluorosulfonic Acid Membranes Measured via Hydrogen Pump Operation. J. Electrochem. Soc. 2017, 164 (12), F1272-F1278. Figure 1