Advanced Anion Exchange Membrane Electrolyser with 360 cm² Active Cell Area

EFCF 2025: Fuel Cells, Electrolysers & H2 Processing 1 - 4 July 2025, Lucerne Switzerland https://doi.org/10.5281/zenodo.17244119 A0802 Page 1/6 A0802 Advanced Anion Exchange Membrane Electrolyser with 360 cm² Active Cell Area Shiva Kumar Sampangi*, Charath Krishna Jarubula, Mohamed Elasmar, Lars Röntzsch Brandenburg University of Technology Cottbus-Senftenberg, Hydrogen Research Center, Siemens-Halske-Ring 13, Cottbus/Germany; *Contact corresponding authors: www.EFCF.com/ContactRequest Abstract Anion Exchange Membrane Water Electrolysis (AEMWE) has emerged as a promising technology for generating green hydrogen, particularly using intermittent renewable energy sources. AEMWE offers a compelling opportunity for cost-effective and sustainable hydrogen production by combining the advantages of traditional alkaline water electrolysis, such as the use of abundant and low-cost catalysts, with the benefits of Proton Exchange Membrane (PEM) electrolysis, which includes membrane separation with pure or lowconcentration alkaline water and operation at high current densities. However, the widespread commercialization of AEMWE remains in its early stages, with small-scale active cell areas (less than 300 cm²) and ongoing challenges related to performance and durability. Consequently, it is vital to develop high-performance, durable AEMWE cells with larger active areas to facilitate the broader adoption of this technology. This contribution presents our recent progress in AEMWE, focusing on the development of cells with an active area of up to 360 cm². In particular, we are advancing AEMWE technology to Technology Readiness Level (TRL) 5/6, incorporating precious metal-free catalysts and advanced membranes to enhance the flexibility and efficiency of hydrogen production. As part of this effort, we have designed and experimentally tested a 100 cm² AEMWE cell and conceptualized and designed a 4-kW short-stack with a total active cell area of 1800 cm², as shown in Figure. 1, for high-pressure operation at 30 bar. Our ongoing efforts includes the laboratory testing of this newly designed stack at high pressure operation and evaluating its electrochemical performance and durability up to 1,000 h continuous operation using precious metal-free electrocatalysts. Figure 1. Newly designed AEM water electrolyser five-cells stack (5 x 360cm2) with an increased single cell active area of 360 cm2. EFCF 2025: Fuel Cells, Electrolysers & H2 Processing 1 - 4 July 2025, Lucerne Switzerland https://doi.org/10.5281/zenodo.17244119 A0802 Page 2/6 Introduction Anion Exchange Membrane (AEM) water electrolysis is an emerging and promising technology for sustainable production of hydrogen. It combines the advantages of both traditional alkaline water electrolysis and proton exchange membrane (PEM) electrolysis, offering a cost-effective and environmentally friendly pathway for generating green hydrogen from water using renewable energy [1, 2]. Typically, in water electrolysis, water is split into hydrogen and oxygen through electrochemical reactions, but unlike PEM water electrolysis systems that use a proton-conducting membrane, AEM systems use a membrane that conducts hydroxide ions (OH⁻) from the cathode to the anode. This allows for the use of non-precious metal catalysts and less corrosive alkaline conditions, thus, significantly reducing materials costs. However, the wide spread commercialization of AEM Water Electrolysis technology remains in its infancy, with current systems typically featuring small active cell areas (below 300 cm²) and facing ongoing limitations in durability [3]. To enable large-scale deployment, it is crucial to develop AEMWE cells that combine high efficiency, long-term stability, and expanded active areas. 1. Scientific Approach To address the challenges associated with AEM water electrolysis, during the last decade, extensive research efforts are directed to development of electrocatalysts, membranes and its system optimizations for increasing performance and durability [4, 5]. For instance, Zhiheng Li et al. [6] developed a nickel-iron electrocatalyst called CAPist-L1 using a simple seed-assisted nucleation method. This catalyst showed excellent oxygen evolution reaction (OER) activity with low overpotentials of 220 ± 4.5 mV at 1,000 mA cm⁻² and 283 ± 12.7 mV at 5,000 mA cm⁻². It also maintained stability over 15,200 hours at 1,000 mA cm⁻². In the study, CAPist-L1 (3.5 mg cm⁻²) was paired with a Ni₄Mo/MoO₂@NF cathode and a terphenyl-based polymer membrane (PAP-TP-85, ~45 μm thick) to test water electrolysis performance, which was benchmarked against IrO2 and NiFe-LDH catalysts. Further, Xu et al. [7] developed an anion exchange membrane based on styrene-b-ethylene-b-butylene-bstyrene copolymer (SEBS) with piperidinium-functionalized flexible side chains, achieving improved hydroxide ion conductivity of 20.8 mS cm⁻¹ at room temperature. Membrane electrode assemblies using Pt/C and Ir-black catalysts delivered current densities of 275 and 680 mA cm⁻² at 2 V and 60°C. Durability testing over 330 hours showed a moderate degradation rate, demonstrating the membrane’s stable performance. However, most of the scientific literatures report on electrocatalyst and membrane developments, whereas a limited number of reports is available on electrolyser stack developments and AEMWE system optimizations [8]. Therefore, the present study aims to develop electrolyser cell with an increased electrode active are of 360 cm2 used in a five-cell stack to systematically evaluate and optimize electrochemical performance and durability up to 1,000 h continuous operation. 2. Experiments 2.1 AEM water electrolyser cell, stack design and construction. The development of AEMWE cells and stacks is essential for enabling efficient and scalable hydrogen production. The single cell assembly comprised key components such as the membrane, catalyst-coated electrodes, flow field separator plates, and end plates, all designed to maximize ionic conductivity while minimizing ohmic and activation losses. The EFCF 2025: Fuel Cells, Electrolysers & H2 Processing 1 - 4 July 2025, Lucerne Switzerland https://doi.org/10.5281/zenodo.17244119 A0802 Page 3/6 cell configuration ensured even distribution of electrolyte and effective removal of generated gases, thereby improving overall performance. To optimize cell design for hydrogen generation, a 100 cm² single cell was initially developed, assembled, and tested under varied operating conditions. This cell included nickel current collectors, gas diffusion layers, EPDM gaskets, and nickel flow-field plates featuring straight parallel channels. Transparent polyacrylic end plates were used to visually monitor gas evolution and bubble formation during operation. For cell assembly, the MEA was placed between the flow-field plates, followed by gas diffusion layers and current collectors, then secured with nuts and bolts tightened to 2.5 N·m torque. Building on insights gained from these experiments, a larger 360 cm² single cell and a five-cell stack were subsequently designed and constructed, as shown in Figure 2. These units incorporate novel flow-field configurations to ensure homogeneous reactant distribution and efficient thermal management, particularly during high-pressure operation up to 30 bar. Materials were selected for their chemical stability and mechanical robustness in alkaline environments. This systematic development approach establishes a foundation for scalable, durable, and high-performance AEM electrolysis systems suitable for industrial applications. Figure 2. Newly designed AEM water electrolyser single cell with increased electrode active area of 360 cm2 2.2 Fabrication of Membrane Electrode Assembly The membrane electrode assembly (MEA) was prepared using the catalyst-coated membrane (CCM) method [9]. First, separate catalyst inks for the anode (NiMoO₂) and cathode (30% Ni/C) were formulated by mixing the catalyst powders with 10% FAA-3 ionomer solution, ethanol, and deionized water. The mixtures were ultrasonicated for 60 min at 35 kHz to ensure proper dispersion. The cathode ink was applied directly onto the Fumasep FAA-3-130 membrane using a Sono-Teck spray coater. Due to agglomeration and clogging issues encountered with the spray coater for the anode catalyst, the anode ink was applied using a traditional brush coating method. Catalyst loadings were controlled at 0.4 mg/cm² for the cathode and 1 mg/cm² for the anode. Finally, the coated membrane was hotpressed at 60°C under 30 bar pressure for 3 min to form a final MEA. It is further assembled in an AEM electrolyser cell and studied its performance and measured the current-voltage polarization curves. EFCF 2025: Fuel Cells, Electrolysers & H2 Processing 1 - 4 July 2025, Lucerne Switzerland https://doi.org/10.5281/zenodo.17244119 A0802 Page 4/6 2.3 Electrolysis performance evolution. The electrochemical performance of the developed AEM electrolyser cell was systematically evaluated using a custom-designed electrolyser test station, as shown in Figure 3. This test station integrates advanced electrochemical instrumentation to ensure accurate and reproducible measurements of the cell’s behavior under various operating conditions. The core equipment includes a Gamry 3000 potentiostat combined with a 30 A booster to extend the current range, along with a DC power supply capable of delivering up to 340 A, providing the flexibility to simulate a wide range of load scenarios. Electrolysis experiments were conducted using a 1 M KOH solution, continuously circulated at a controlled flow rate of 1 dm³/min through both the anode and cathode compartments. This continuous flow ensures efficient reactant supply and effective removal of gas products, which is critical for maintaining stable cell performance. Temperature control was achieved using integrated heat exchangers, maintaining the cell temperature within the range of 30°C to 60°C. This allowed investigation into how elevated temperatures influence electrochemical kinetics and overall cell efficiency. Further, current-voltage (I-V) curves were recorded by varying the applied current through the potentiostat and booster system, enabling detailed characterization of the cell’s voltage response at different current densities. These measurements provided valuable insights into activation losses, ohmic resistance, and mass transport limitations, thereby helping to identify performance bottlenecks and opportunities for optimization. Figure 3. AEM water electrolyser test station, which includes a 100 cm2 AEM single cell and their components. 3. Results The performance of the developed electrolyser was evaluated using a custom-designed electrolyser test station. The electrolysis experiments were conducted using a 1M KOH solution over a temperature ranges from 30°C to 70°C. During the experiments, the cell’s current-voltage characteristics were recorded across varying current densities to assess its electrochemical performance under different thermal conditions. The results indicate that at an operating temperature of 70°C, the electrolyser achieved a current density of 300 mA cm⁻² at a cell voltage of 2.08 V, as shown in Figure 4. Furthermore, it was observed that increasing the temperature from 30°C to 70°C led to a noticeable reduction in the cell voltage required to reach the same current density. Specifically, the voltage decreased from 2.20 V EFCF 2025: Fuel Cells, Electrolysers & H2 Processing 1 - 4 July 2025, Lucerne Switzerland https://doi.org/10.5281/zenodo.17244119 A0802 Page 5/6 at 30°C to 2.08 V at 70°C. This improvement in performance can be attributed to enhanced electrochemical reaction kinetics at elevated temperatures, which reduce the overall energy loss within the system [10]. Figure 4. Current–voltage polarization curves of 100 cm² AEM electrolyser contains Fumasep®FAA-3-130 membrane and non-precious metal catalysts of NiMoO4 and 30% Ni/C. 4. Summary and Outlook The present study outlines the development of an AEMWE cell, focusing on innovative cell configurations and membrane electrode assemblies (MEAs). This work represents part of the preliminary outcomes from the Energy Innovation Centre (EIZ) at Brandenburg University of Technology (BTU), conducted within the framework of a project funded by the Federal Government through the Structural Development Act for coal-mining regions. As part of this initiative, a 100 cm² AEM single cell was designed, fabricated, and tested under various experimental conditions to evaluate its electrochemical performance. Current efforts are directed toward enhancing cell performance through the optimization of operational parameters and the integration of advanced membrane materials and precious-metal-free electrocatalysts. Building upon these initial results, a larger 360 cm² single cell and a fivecell stack (4-kW) have been developed, featuring novel flow-field configurations tailored for high-pressure operation up to 30 bar. These developments are a step toward scaling the technology (TRL 5/6) for practical, industrial-scale hydrogen production using AEM electrolysis. Future efforts also will focus on the direct integration of the electrolyser system with downstream processes for the synthesis of green fuels such as methane and methanol, contributing to the advancement of fully renewable energy-to-fuel pathways. EFCF 2025: Fuel Cells, Electrolysers & H2 Processing 1 - 4 July 2025, Lucerne Switzerland https://doi.org/10.5281/zenodo.17244119 A0802 Page 6/6 Acknowledgements The authors gratefully acknowledge the support of the Federal Ministry of Education and Research (BMBF) and the State of Brandenburg (ILB) within the framework of the joint project "EIZ – Energy Innovation Center" (Project Numbers: 85056897 and 03SF0693A), funded through the Structural Development Act for Coal-Mining Regions. References 1. Zhiqing Tang, Baoxin Wu, Kejun Yan, Jiahui Luo, Mahmood Ul Haq, Lin Zeng, Longterm stability for anion exchange membrane water electrolysis: Recent development and future perspectives. Future Batteries 5 (2025)100024. 2. Jingyi Wang, Jinbin Yang, Yu Feng, Jing Hua, Zhengjian Chen, Mei Liao, Jingran Zhang, Jiang Qin, Comparative experimental study of alkaline and proton exchange membrane water electrolysis for green hydrogen production, Applied Energy (379, 2025) 124936. 3. 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