Multiphysics simulation of novel double-spiral flow channel design for circular bipolar plate in proton exchange membrane electrolyzer

The proton exchange membrane water electrolysis (PEMWE) technology is a highly promising method for hydrogen production. The flow field structure is a key factor affecting the electrolyzer’s performance and overall cost. The commonly used flow field designs are typically parallel flow fields or serpentine flow fields. However, parallel flow fields often suffer from an uneven distribution of reactants, which can negatively impact electrolyzer performance. Serpentine flow fields, on the other hand, exhibit higher pressure drops, leading to increased energy consumption. Furthermore, research on circular planar flow field designs in PEMWE has been limited. Therefore, this study proposes a novel annular flow field design based on a circular plane using Murray’s branching law, with comparative analysis against parallel and serpentine flow fields. This design aims to address the aforementioned issues. A three-dimensional numerical model coupling multiple physical fields was developed with the aim of verifying the effectiveness of the annular flow field design in terms of pressure drop, velocity distribution, temperature distribution, hydrogen distribution, and polarization curves. To confirm the model’s reliability, bipolar plates with the novel annular flow field were fabricated and assembled into a single cell for validation. The results show that the novel annular flow field exhibits optimal electrolytic performance and can significantly improve the uniformity of flow and temperature distribution in PEMWE. At a voltage of 2.6 V, the current density increased by 29.99% and 13.84% compared to the parallel and serpentine flow fields, respectively. The velocity distribution was the most uniform, and the average temperature of the Membrane Electrode Assembly (MEA) decreased by approximately 6.08 K and 6.84 K compared to the parallel and serpentine flow fields, respectively. Notably, the pressure drop of the annular flow field was significantly reduced, with reductions of 53.63% and 46.09% compared to the parallel and serpentine flow fields, respectively. This study provides an effective solution for the design of circular plane flow fields in PEMWE.

Membraneless Electrolyzers for Low-Cost Hydrogen Production in a Renewable Energy Future

Systematic assessment of the anode flow field hydrodynamics in a new circular PEM water electrolyser

A 3-D multiphase model of proton exchange membrane electrolyzer based on open-source CFD

Commercialization of proton exchange membrane (PEM) electrolyzers for green hydrogen production have been recently achieved, but with a limited scale of low gigawatts (GW).1 Large-scale and sustainable deployment of PEM electrolyzers will face the challenges of scarcity and high cost of iridium (Ir) used in the anode to catalyze oxygen evolution reaction (OER). A 1 MW PEM electrolyzer stack currently uses ~0.4 kg of Ir based on an Ir loading of 1.5 mg/cm2, which contributes ~$60k cost per stack.2 Moreover, the Ir production has been about 8 tons/year in recent years.3 This can only support an annual production of 5 GW PEM electrolyzer if assuming 25% Ir is available for PEM electrolyzers with the same Ir loading. Therefore, lowering the Ir loading in PEM electrolyzers is urgently needed to meet the rapid expansion of the PEM electrolysis market.Several groups including Plug have developed supported Ir catalysts to lower the Ir loading by a factor of 5 without sacrifice in efficiency.4-8 However, all support used by far is non- or poorly electrically conductive. The conductivity of the electrodes relies solely on the surface IrOx, which sets stringent limits on the catalyst/electrode development, especially with low Ir contents. Here we first argue from fundamental aspects that the catalysts/electrodes with Ir on conductive support can be free of these limits. We further show that platinum (Pt) and titanium diboride (TiB2) powders are feasible candidates as conductive support for Ir-based OER catalysts. We demonstrated a TiB2 supported IrOx (IrOx/TiB2) catalyst synthesized via wet chemistry deposition without post heat treatment combines a mass activity towards OER with high conductivity. Its conductivity of ~30 S/cm2 is comparable to that of Vulcan carbon, and ~105 times that of the counterpart IrOx/W-TiO2 (W-TiO2 represents commercial tungsten doped TiO2 nanoparticles). Meanwhile, the IrOx/TiB2 catalyst shows a mass activity comparable to that of the counterpart IrOx/W-TiO2, twice that of commercial Ir black, and 50 times that of a commercial IrO2/TiO2 catalyst in acidic solution. Durability test showed that the Ir dissolution of the IrOx/TiB2 in acidic solution holding at 2 V for 100 hours is comparable to that of Ir black. Characterization of the IrOx/TiB2 showed small hydrous IrOx nanoparticles (1-2 nm) uniformly distributed on the surface of TiB2 nanoparticles (~58 nm) with an Ir content of ~33±7 wt%. Membrane electrode assembly evaluation on the IrOx/TiB2 catalyst is undergoing. The results will be reported and discussed. References (1) IEA, World Energy Outlook, 2022. https://iea.blob.core.windows.net/assets/830fe099-5530-48f2-a7c1-11f35d510983/WorldEnergyOutlook2022.pdf (accessed 2023-02-12).(2) Mittelsteadt, C. (Invited) Ir Strangelove: Or How I Learned to Stop Worrying and Embrace the PEM. ECS Meeting s 2022, MA2022-01, 1335-1335.(3) Seeking Alpha Home Page. https://seekingalpha.com/article/4399727-sibanye-should-benefit-from-hydrogen-wars-thanks-to-iridium-exposure (accessed 2023-02-12).(4) Böhm, D.; Beetz, M.; Gebauer, C.; Bernt, M.; Schröter, J.; Kornherr, M.; Zoller, F.; Bein, T.; Fattakhova-Rohlfing, D. Highly conductive titania supported iridium oxide nanoparticles with low overall iridium density as OER catalyst for large-scale PEM electrolysis. Applied Materials Today 2021, 24, 101134.(5) Pham, C. V.; Bühler, M.; Knöppel, J.; Bierling, M.; Seeberger, D.; Escalera-López, D.; Mayrhofer, K. J. J.; Cherevko, S.; Thiele, S. IrO2 coated TiO2 core-shell microparticles advance performance of low loading proton exchange membrane water electrolyzers. Appl. Catal. B‐Environ. 2020, 269, 118762.(6) Zhao, S.; Stocks, A.; Rasimick, B.; More, K.; Xu, H. Highly Active, Durable Dispersed Iridium Nanocatalysts for PEM Water Electrolyzers. J. Electrochem. Soc. 2018, 165, F82-F89.(7) Oakton, E.; Lebedev, D.; Povia, M.; Abbott, D. F.; Fabbri, E.; Fedorov, A.; Nachtegaal, M.; Copéret, C.; Schmidt, T. J. IrO2-TiO2: A high-surface-area, active, and stable electrocatalyst for the oxygen evolution reaction. ACS Catal. 2017, 7, 2346-2352.(8) Lewinski, K. A.; van der Vliet, D.; Luopa, S. M. NSTF advances for PEM electrolysis-the effect of alloying on activity of NSTF electrolyzer catalysts and performance of NSTF based PEM electrolyzers. ECS Trans 2015, 69, 893.

Water electrolyzers and fuel cells can be used to create a closed loop system for space exploration. Electrolyzers allow for reliable self-sustainable generation of hydrogen and oxygen for energy storage, followed by conversion into electrical energy in a fuel cell. A first-order safety concern for water electrolyzer operation is hydrogen crossover. Transport of hydrogen to the oxygen rich anode in proton exchange membrane (PEM) water electrolyzers poses safety concerns when the hydrogen concentration in the anode flow field approaches the hydrogen lower flammability limit (LFL). Hydrogen storage efficiency relies on high hydrogen pressure, leading to pressure-driven hydrogen crossover. Mitigation of hydrogen crossover through research and development of a platinum metal recombination layer has been demonstrated in high performing, durable PEMWEs.1-4 Ouimet4 explored the use of a novel dual recombination layer configuration to mitigate PEM water electrolyzer hydrogen crossover. In addition, the current state of the art for PEM fuel cells and water electrolyzers rely on perfluoro-sulfonated acid (PSFA) based membranes. There are significant challenges facing the use of PSFA-based membranes; namely, environmental contamination and performance limitations. The use of a hydrocarbon membrane allows for the development of a PSFA-free system that shows higher efficiency and durability. Investigation of hydrocarbon membranes pave way for developing a PEM water electrolyzer that will demonstrate improved gas permeability resistance, mechanical strength, and thermal stability.5-8 There is a need for both hydrogen crossover mitigation strategies and durability testing with hydrocarbon membranes.The research outlined in this work is focused on the development of PSFA-free PEM water electrolyzers with low hydrogen crossover. In this work, the dual recombination layer configuration will be incorporated into a hydrocarbon membrane for PEM water electrolysis. Polarization, electrochemical impedance spectroscopy, electrochemical equivalent circuits, distribution of relaxation times, and materials characterization will be used to investigate the cell performance and durability. References G. Mirshekari, R. Ouimet, Z. Zeng, H. Yu, S. Bliznakov, L. Bonville, A. Niedzwiecki, C. Capuano, K. Ayers, and R. Maric, “High-performance and cost-effective membrane electrode assemblies for advanced proton exchange membrane water electrolyzers: Long-term durability assessment,” international journal of hydrogen energy, vol. 46, no. 2, pp. 1526–1539, 2021.Z. Zeng, R. Ouimet, L. Bonville, A. Niedzwiecki, C. Capuano, K. Ayers, A. P. Soleymani, J. Jankovic, H. Yu, G. Mirshekari, et al., “Degradation mechanisms in advanced meas for pem water electrolyzers fabricated by reactive spray deposition technology,” Journal of The Electrochemical Society, vol. 169, no. 5, p. 054536, 2022.A. Martin, D. Abbas, P. Trinke, T. Böhm, M. Bierling, B. Bensmann, S. Thiele, and R. Hanke-Rauschenbach, “Communication—proving the importance of ptinterlayer position in pemwe membranes for the effective reduction of the anodic hydrogen content,” Journal of The Electrochemical Society, vol. 168, no. 9, p. 094509, 2021.R. J. Ouimet, “Catalyst development by a novel fabrication process for energy applications,” University of Connecticut Doctoral Dissertation, 2021.P. Trinke, P. Haug, J. Brauns, B. Bensmann, R. Hanke-Rauschenbach, and T. Turek, “Hydrogen crossover in pem and alkaline water electrolysis: mechanisms, direct comparison and mitigation strategies,” Journal of The Electrochemical Society, vol. 165, no. 7, p. F502, 2018.P. Trinke, B. Bensmann, and R. Hanke-Rauschenbach, “Current density effect on hydrogen permeation in pem water electrolyzers,” International Journal of Hydrogen Energy, vol. 42, no. 21, pp. 14355–14366, 2017.H. Q. Nguyen and B. Shabani, “Proton exchange membrane fuel cells heat recovery opportunities for combined heating/cooling and power applications,” Energy Conversion and Management, vol. 204, p. 112328, 2020.C. Klose, T. Saatkamp, A. Münchinger, L. Bohn, G. Titvinidze, M. Breitwieser, K. D. Kreuer, and S. Vierrath, “All-hydrocarbon mea for pem water electrolysis combining low hydrogen crossover and high efficiency,” Advanced Energy Materials, vol. 10, no. 14, p. 1903995, 2020.

Energy and exergy analysis of hydrogen production by a proton exchange membrane (PEM) electrolyzer plant

Proton conducting polymer electrolyte membrane (PEM) electrolysis has emerged as the currently favored research area to enable a global transformation of the energy system with hydrogen from renewable sources as a critical central feature. The hydrogen council has suggested that hydrogen impacts by 2050 could be $2.5T annually and 18% of total global energy demand.[1] While other electrolysis routes including traditional alkaline (based on aqueous KOH), alkaline membrane (emerging) and solid oxide electrolysis are all also being explored, and other possible hydrogen production pathways exist. The ability of PEM electrolysis to fit the needs of the emerging energy system as a dispatchable resource meeting cost, performance and durability requirements most effectively has led to a greater focus on PEM electrolysis than other electrolysis approaches within the global R&D community. The extent PEM electrolysis will establish itself commercially will depend largely on the advances made in the next several years.Much of the focus on PEM electrolysis has been centered around the advances made in PEM fuel cells, and the belief that these advances can be translated to PEM electrolysis systems. In particular, PEM fuel cells have largely been designed for transportation applications where they operate at low duty cycles (mostly off), and experience significant start-stop cycling (multiple times per day) while still achieving requisite performance and durability (several years).[2] Renewable energy sources are dramatically impacting the cost and availability of electricity and the ability to translate these resources into other energy sectors – most notably transportation and industry. While it is hoped that PEM electrolyzers can achieve cost, performance and durability targets, the research needs and challenges are not identical to PEM fuel cells.A new Department of Energy Consortium (H2NEW – Hydrogen from Next-generation Electrolyzers of Water) funded out of the Hydrogen and Fuel Cell Technologies Office is focused on enabling the cell-level fundamental understanding and advances required to address achieving $2/kg hydrogen through electrolysis. The primary focus of this effort is PEM electrolysis, the focus of the talk.A challenge in meeting the cost, performance and durability of PEM electrolysis systems is that current systems have had a strong emphasis on efficiency and durability. This means that cost has not been a primary concern such that systems could be “over-engineered” using extra or more expensive components and processing techniques. This approach has meant that little is understood about fundamental degradation rates relevant to systems that have not been over-engineered. Additionally, the markets that these devices have been sold into have typically operated under continuous conditions rather than the variable, intermittent load profiles that could couple to renewable or low-cost electricity inputs expected in the future. A clear understanding of the optimum system and operating conditions is not well understood at this time, nor is the impact of such operating conditions on performance and durability.Research needs place a high priority on durability under variable operating conditions. Specific components have susceptibility to different performance and durability impacts. In this talk, the impact of operating conditions and a discussion of projected operating conditions will be discussed. The concerns for both performance and durability will be discussed at the cell level with consideration of various cell components including catalyst, polymer, electrode, and porous transport layers. Accelerated stress tests for components in cells is a critical need and will also be presented. Finally, system and techno-economic considerations will also be included.References Hydrogen Council. “Hydrogen Scaling Up.” November 2017. http://hydrogencouncil.com/hydrogen-scaling-up/ B Pivovar, N Rustagi, S Satyapal, Electrochemical Society Interface 27 (1), 47.

Proton exchange membrane (PEM) water electrolysis has become increasingly attractive due to the penetration of renewable energy (e.g, solar and wind). Hydrogen production from PEM water electrolysis is advantageous over other technologies due to its simple and clean nature. Membrane and electrode assemblies (MEAs) of PEM electrolyzers typically use iridium (Ir) as an anode catalyst and Pt as a cathode catalyst. Performance and durability of the MEAs play an essential role for the cost and viable commercialization of PEM water electrolysis. However, unlike the well-established MEA benchmarks of PEM fuel cells, the performance and durability of PEM electrolyzer MEAs have not been thoroughly studied. The objective of this work is to establish benchmark MEA performance and durability for PEM water electrolysis. For this purpose, a series of oxygen evolution reaction (OER) catalysts, which includes commercial Ir black and various Ir nanostructures, has been evaluated under test protocols established at Giner Inc. These approaches include high-voltage hold (>1.8 V), accelerated stress test (e.g., voltage cycling from 1.4 to 2.0 V), and constant low-current operations. The polarization curves of the MEAs will be obtained after each test. The morphology and structure of MEAs after durability tests will be characterized to correlate to their performance and durability. The established performance and durability may provide metrics and guidance to the community of PEM water electrolysis. Acknowledgement: The financial support is from the Department of Energy under the Contract Grant DE-SC0007471.

The high cost of noble metals is one of the key factors hindering the large‐scale application of proton exchange membrane (PEM) water electrolyzer for hydrogen production. Recently, single‐atom catalysts (SACs) with a potential of maximum atom utilization efficiency enable lowering the metal amount as much as possible; unfortunately, their durability remains a challenge under PEM water electrolyzer working conditions. Herein, a highly‐stable alloyed Pt SAC is demonstrated through a plasma‐assisted alloying strategy and applies to a PEM water electrolyzer. In this catalyst, single Pt atoms are firmly anchored onto a Ru support via a robust metal–metal bonding strength, as evidenced by these complementary characterizations. This SAC is used in a PEM water electrolyzer system to achieve a cell voltage as low as 1.8 V at 1000 mA cm−2. Impressively, it can operate over 1000 h without obvious decay, and the catalyst is present in the form of individual Pt atoms. To the knowledge, this will be the first SAC attempt at a cell level toward long‐term PEM. This work paves the way for designing durable SACs employed in the actual working condition in the PEM water electrolyzer.

Proton exchange membrane fuel cells need cooling plates with strong heat exchange capacity to maintain temperature balance. In order to obtain better cooling performance, four new types of flow field distribution of cooling plate are designed, including local serpentine channel, local parallel channel and the flow field in which the four channels are symmetrically distributed along the diagonal and horizontal centerline of the cooling plate. The maximum temperature, temperature difference, temperature uniformity index and pressure drop of the multi-channel cooling plate under different working conditions are analyzed by numerical simulation. The results show that the multi-channel design can effectively enhance the heat transfer effect of the cooling plate and reduce the pressure drop. The local serpentine channel design can increase the fluidity of the coolant, avoid local reflux, make the temperature distribution more uniform and avoid local overheating. The maximum temperature of local serpentine channel flow field is 1.2 K lower than that of local parallel channel flow field. The pressure drop of internal parallel flow field design is 2.58 kPa, which is 62% lower than that the design of internal serpentine flow field. Increasing the inlet coolant flow can strengthen the heat transfer capacity of the cooling plate, when the flow rate increases from 2e-6 m3/s to 4e-6 m3/s, the maximum decrease is 8.53% of Model6. But it will increase the pressure drop of the channel with long cooling channel, the maximum pressure drop increase is 924 kPa when the inlet flow increases from 6e-6 m3/s to 8e-6 m3/s.

For the scale-up of proton exchange membrane (PEM) water electrolysis, understanding the cell behavior on industrial scale is a prerequisite. A proper distribution of current and temperature in the cell can improve performance and decrease overall degradation effects. Due to water consumption as well as the concomitant gas evolution and accumulation, gradients and inhomogeneities along the reaction coordinate are expected. These effects increase along the water supply channels of a flow field and are expected to lead to spatial gradients in cell performance and temperature. In this study we present a new test cell that is segmented along the flow field channels and is designed for the operation at high current densities. We show polarization curve measurements at 10 bar differential pressure up to 10 A∙cm−2 at ∼2.7 V without observing any mass transport limitations and conduct current density, temperature and impedance distribution measurements. At harsh conditions (low water flow rates of 2 ml∙min−1∙cm−2 and high current densities up to 6 A∙cm−2) we see significant temperature and current density increase of ∼13 K and 0.7 A∙cm−2 which can be explained by decreasing membrane resistance determined via EIS of >10 mΩ⋅cm2 along the channel. The validity of the impedance measurements is proofed by comparison of the impedance at 100 mHz with the direct current resistance of the cell extracted by the local slope of the polarization curve.

Proton exchange membrane (PEM) water electrolysis is considered a promising method for producing green hydrogen. PEMs are vital in conducting protons and preventing hydrogen from permeating to the anode side. Additionally, the PEMs need high durability to withstand the harsh environment of PEM water electrolysis over extended periods. Therefore, high proton conductivity, high mechanical strength, high chemical stability, low hydrogen permeability, and ease of handling are required in PEM properties. In general, PEMs containing perfluorinated sulfonic acid (PFSA) polymers are known as the best candidates to meet these requirements. Due to their exceptional proton conductivity and chemical stability, they are used in several electrochemical devices, including water electrolysis.In the future, there will be a demand to increase the proton conductivity of PEMs to reduce the energy required for hydrogen production in the water electrolysis industry. Decreasing the thickness of PEMs is an easy way to achieve high proton conductivity, but it tends to result in higher hydrogen permeability and lower mechanical strength. Overcoming this trade-off is essential to enhancing the hydrogen productivity of PEM water electrolysis.Since 1975, AGC has developed many kinds of PFSA polymers by introducing original monomers and then producing FORBLUETM products in-house. AGC recently released the FORBLUETM S-SERIES, a family of PFSA membrane products designed explicitly for PEM water electrolysis. This series is expected to overcome the trade-off issues by applying our advanced polymer and membrane technology. This talk will provide an overview of the development, including the novel PFSA polymers.

Hydrogen, as a clean energy carrier, is of great potential to be an alternative fuel in the future. Proton exchange membrane (PEM) water electrolysis is hailed as the most desired technology for high purity hydrogen production and self-consistent with volatility of renewable energies, has ignited much attention in the past decades based on the high current density, greater energy efficiency, small mass-volume characteristic, easy handling and maintenance. To date, substantial efforts have been devoted to the development of advanced electrocatalysts to improve electrolytic efficiency and reduce the cost of PEM electrolyser. In this review, we firstly compare the alkaline water electrolysis (AWE), solid oxide electrolysis (SOE), and PEM water electrolysis and highlight the advantages of PEM water electrolysis. Furthermore, we summarize the recent progress in PEM water electrolysis including hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts in the acidic electrolyte. We also introduce other PEM cell components (including membrane electrode assembly, current collector, and bipolar plate). Finally, the current challenges and an outlook for the future development of PEM water electrolysis technology for application in future hydrogen production are provided.

Looking for alternative energy sources has been an inevitable trend since the oil crisis, and close attentioned has been paid to hydrogen energy. The proton exchange membrane (PEM) water electrolyzer is characterized by high energy efficiency, high yield, simple system and low operating temperature. The electrolyzer generates hydrogen from water free of any carbon sources (provided the electrons come from renewable sources such as solar and wind), so it is very clean and completely satisfies the environmental requirement. However, in long-term operation of the PEM water electrolyzer, the membrane material durability, catalyst corrosion and nonuniformity of local flow, voltage and current in the electrolyzer can influence the overall performance. It is difficult to measure the internal physical parameters of the PEM water electrolyzer, and the physical parameters are interrelated. Therefore, this study uses micro-electro-mechanical systems (MEMS) technology to develop a flexible integrated microsensor; internal multiple physical information is extracted to determine the optimal working parameters for the PEM water electrolyzer. The real operational data of local flow, voltage and current in the PEM water electrolyzer are measured simultaneously by the flexible integrated microsensor, so as to enhance the performance of the PEM water electrolyzer and to prolong the service life.