Novel Pyrrolidinium-Functionalized Styrene-b-ethylene-b-butylene-b-styrene Copolymer Based Anion Exchange Membrane with Flexible Spacers for Water Electrolysis

Ziqi Xu; Sofia Delgado; Vladimir Atanasov; Tobias Morawietz; Aldo Saul Gago; Kaspar Andreas Friedrich

doi:10.3390/membranes13030328

Novel Pyrrolidinium-Functionalized Styrene-b-ethylene-b-butylene-b-styrene Copolymer Based Anion Exchange Membrane with Flexible Spacers for Water Electrolysis

Membranes (Basel). 2023 Mar 13;13(3):328. doi: 10.3390/membranes13030328.

Authors

Ziqi Xu¹, Sofia Delgado², Vladimir Atanasov³, Tobias Morawietz^{1

4}, Aldo Saul Gago¹, Kaspar Andreas Friedrich^{1

5}

Affiliations

¹ German Aerospace Center (DLR), Institute of Engineering Thermodynamics, Pfaffenwaldring 38-40, 70569 Stuttgart, Germany.
² Laboratory for Process Engineering, Environmental, Biotechnology and Energy (LEPABE), Faculty of Engineering of University of Porto, Rua Roberto Frias S/n, 4200-465 Porto, Portugal.
³ Institute of Chemical Process Engineering, University of Stuttgart, Boeblinger Strasse 78, 70199 Stuttgart, Germany.
⁴ Faculty of Science, Energy and Building Services, Esslingen University of Applied Sciences, Kanalstraße 33, 73728 Esslingen am Neckar, Germany.
⁵ Institute of Building Energetics, Thermal Engineering and Energy Storage (IGTE), University of Stuttgart, Pfaffenwaldring 6, 70569 Stuttgart, Germany.

Abstract

Anion exchange membranes (AEM) are core components for alkaline electrochemical energy technologies, such as water electrolysis and fuel cells. They are regarded as promising alternatives for proton exchange membranes (PEM) due to the possibility of using platinum group metal (PGM)-free electrocatalysts. However, their chemical stability and conductivity are still of great concern, which is appearing to be a major challenge for developing AEM-based energy systems. Herein, we highlight an AEM with styrene-b-ethylene-b-butylene-b-styrene copolymer (SEBS) as a backbone and pyrrolidinium or piperidinium functional groups tethered on flexible ethylene oxide spacer side-chains (SEBS-Py2O6). This membrane reached 27.8 mS cm^-1 hydroxide ion conductivity at room temperature, which is higher compared to previously obtained piperidinium-functionalized SEBS reaching up to 10.09 mS cm^-1. The SEBS-Py206 combined with PGM-free electrodes in an AWE water electrolysis (AEMWE) cell achieves 520 mA cm^-2 at 2 V in 0.1 M KOH and 171 mA cm^-2 in ultra-pure water (UPW). This high performance indicates that SEBS-Py2O6 membranes are suitable for application in water electrolysis.

Keywords: anion exchange membrane; anion exchange membrane water electrolysis; chemical stability; conductivity; flexible oxide spacers.

Grants and funding

This research was funded by the EU project NEWELY funded by Fuel Cells and Hydrogen 2 Joint Undertaking (now Clean Hydrogen Partnership) under Grant Agreement No. 875118 and Chinese Scholarship Council (201706060199).