Mechanical and Physio-Chemical Properties of Anion Exchange Membranes and Their Implications on Industrial Scale Water Electrolysis

Abstract

Siemens Energy Global GmbH & Co. KG - Sustainable Energy Systems, Otto-Hahn-Ring 6, 81739 MünchenMembrane based water electrolysis can operate under acidic or alkaline conditions, depending on the nature of the conducting ion in the membrane. Proton conducting membranes became commercially available and sufficiently stable over the last decades, enabling to scale PEM (ProtonExchange Membrane) – electrolysis in the tens of MW range1,2 approaching GW plants.Anion Exchange Membranes (AEM) suffered mainly from limited hydroxide stability. In recent years, AEMs with sufficient initial stability and semi-commercial availability on pilot size draw the attention of industry to invest in developing in AEM electrolysers3,4. On research scale, AEMs are mainly characterized by their ion exchange capacity, conductance, ASR, tensile strength or elongation at break5,6. For industrial application, parameters such as swelling, water uptake, permeability or solubility and viscosity of the corresponding ionomer set boundary conditions for scaling cell sizes into the square meter range and the applicability of high volume manufacturing or coating methods.In the presentation, physio chemical properties of membranes (swelling, water uptake, IEC, conductance, stress/strain and anisotropy ) are brought in context to requirements for > 1000 cm² industrial membrane electrolysis. Investigations on ex-situ characterization of membranes are being compared to different membrane chemistries and implications for larger cell sizes are derived. First results of durability tests at 1.5 A/cm² and potential degradation mechanisms will be presented in an Ir-free electrolysis cell. Changes of morphological features of the membrane electrode assembly arebeing examined by optical and scanning microscopy techniques. Membrane parameters will be correlated to the electrochemical performance (impedance, endurance) in 25 cm² cells. Relevant ex-situ measurable properties are compiled for discussion with the audience.ACKNOWLEDGEMENTThe investigations were partly funded by the BMBF under the contract number AEMready(FKZ:03SF0613B).REFERENCES1 https://www.siemens-energy.com/global/en/offerings/renewable-energy/hydrogen-solutions.html?gclid=EAIaIQobChMIsuu-wMHV wIVktZ3Ch24ngoYEAAYASAAEgJUF_D_BwE.2 https://press.siemens-energy.com/global/en/pressrelease/new-production-facility-berlin-siemens-energy-wants-eliminate-worlds-most-potent .3 https://www.enapter.com/applications4 https://www.enerstack.eu/5 D. Henkensmeier, M. Najibah, C. Harms, J. Zitka, J. o. Electrochemical Energy Conversion and Storage, 2021, Vol. 18, 0240016 K.M. Meek, C.M. Antunes, A. Neyerlin, B.S. Pivovar, “High-Throughput Anion Exchange-Membrane Characterisation at NREL”, Electrochemical Engineering & Materials Chemistry, National Renewable Energy Laboratory, Gold, Colorado, USA