Abstract
The use of bipolar membranes has the potential to broaden the scope of active and stable electrode materials in water and CO2 electrolyzers, and to mitigate challenges related crossover. 1,2 However, the high resistance of commercial bipolar membrane materials under reversed bias and their tendency to delaminate currently limit their practical use in these technologies. This contribution presents a new design strategy of bipolar membranes, where the individual anion- and cation exchange layers are derived from the same backbone chemistry to govern interfacial compatibility. This is achieved through divergent functionalization of a styrene-ethylene-butylene copolymer, through installation of sulfonic acid moieties or quaternary ammonium groups. When combined with earth abundant and active water dissociation catalysts, such as TiO2 or SnO2, the bipolar membrane system shows an order of magnitude higher adhesion force (50 N/m) than bipolar membranes derived from Nafion and PiperION. The polarization behavior under reversed bias is investigated in H-cell tests, and further evaluated in water electrolysis experiments. The dependencies on ion exchange capacity and the water dissociation catalyst loading at the interfacial junction are investigated. While benefiting on high adhesion strength fluorine-free chemistry, the optimized membrane supports current densities up to 500 mA/cm2 at 2.5 V in pure water electrolysis mode when combined with a Pt/C cathode and a noble-metal-free Co3O4 anode. 1 Blommaert, M. A.; Aili, D.; Tufa, R. A.; Li, Q.; Smith, W. A.; Vermaas, D. A. Insights and Challenges for Applying Bipolar Membranes in Advanced Electrochemical Energy Systems. ACS Energy Lett 2021, 2539–2548. 2 Tufa, R. A.; Blommaert, M. A.; Chanda, D.; Li, Q.; Vermaas, D. A.; Aili, D. Bipolar Membrane and Interface Materials for Electrochemical Energy Systems. ACS Appl Energy Mater 2021, 4 (8), 7419–7439. Figure 1
Published Version
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