Proton Exchange Membrane System Research Articles

Theory Guided Discovery of Superior Ru-Based Electrocatalyst for Durable Acidic Oxygen Evolution Reaction

Water electrolysis (WE) using hydrogen evolution reaction is widely recognized as a promising method for clean and sustainable hydrogen production. The currently dominant alkaline-based water electrolysis encounters several challenges including high ohmic resistance, limited current density, low efficiency, and poor long-term stability. Proton exchange membrane (PEM) electrolysis can tackle these challenges by providing efficient proton transfer. However, sluggish oxygen evolution reaction (OER) in acid has been a major long-existing obstacle in PEM systems and, therefore, has attracted great research interest.Due to its high activity and durability, IrO2 is currently considered the only practical OER electrocatalyst in PEM devices. However, Ir’s high cost and low global reserve limit its large-scale applications. Hence, less-expensive catalysts for acidic OER are in great demand. RuO2 has been recognized as an attractive alternative to IrO2 because Ru is ~100x abundant and costs ~10x less. Although RuO2 presents higher activity than IrO2, it deteriorates severely in a few hours due to its dissolution under oxidizing conditions. Its long-term stability remains a big challenge.To overcome the challenge of improving the stability of Ru-based oxides, in this work we provide a rigid theoretical framework of RuO2 dissolution under the influence of other metal species. We show that the stability of Ru-based oxides could be controlled by varying the properties of incorporated metal oxides as well as the synergy to form a complex oxide. Surveying the Materials Project database led to the rationalization of a series of metal elements that could positively improve the stability of RuO2. Guided by our theoretical approach, we conducted high-throughput screening and experimental evaluation of Ru-based oxides for acid OER.Our study discovered a novel Ru-based oxide with superior performance in acid OER application. A new wet-impregnation method was developed to synthesize the desired phase. The as-obtained product were uniform nanoparticles with diameters less than 5 nm in a single rutile structure. The new catalyst showed significantly better performance than pristine RuO2. In the rotating-disk-electrode experiment, our catalyst delivered a current density of 10 mA·cm-2 at an overpotential of less than 170 mV in 0.1 M HClO4. The catalyst exhibited a low degradation rate smaller than 25 μVh-1 for over 200 hours of operation at 10 mA·cm-2. Our results show great promise of Ru-based oxides as Ir-free electrocatalysts for acidic OER in PEM water electrolysis.

Unveiling the Activity-Electrochemically Active Surface Area Relationship in PGM-Free Oxyphosphide OER Electrocatalysts for Alkaline Water Electrolysis

The oxygen evolution reaction (OER) plays a pivotal role in various electrochemical processes, from water splitting to CO2 electroreduction and metal-air batteries. However, the sluggish kinetics of OER, involving multi-electron transfer, necessitate the development of catalysts with high activity and stability. While platinum group metal (PGM) catalysts like IrO2 and RuO2 exhibit high OER activity in proton exchange membrane (PEM) water electrolysis, their cost hinders widespread adoption. Anion Exchange Membrane Water Electrolysis (AEMWE) emerges as a promising technology with the potential to be both cost-effective and sustainable for hydrogen production. It relies on PGM-free OER catalysts, bridging the gap and merging the strengths of PEM and traditional alkaline electrolysis systems Transition metal (TM) oxides, layered double hydroxides, and oxyphosphides, particularly those incorporating Ni, Fe, and Co, emerge as promising OER catalysts for alkaline water electrolysis. Yet, comparing different catalysts remains challenging due to varied testing protocols that influence reported performances, often referenced to geometric surface area. Herein, we address this challenge by evaluating the intrinsic activity and electrochemically active surface area (ECSA) of PGM-free OER catalysts. Employing a colloidal synthesis approach, TM catalysts were synthesized and tested for OER activity and durability in 1 M KOH. Transmission electron microscopy (TEM) imaging revealed a unique porous structure surrounding a metallic core.To estimate the ECSA, cyclic voltammograms were recorded at various scan rates in a non-Faradaic region. The double layer capacitance (Cdl) was evaluated from the slope of current versus scan rate, and a specific capacitance of 40 μF cm-2 was used to calculate the ECSA. [1-4]Preliminary results demonstrate a direct correlation between OER activity and ECSA. The correlation between the BET surface and OER activity was also studied.AcknowledgmentsThis work was supported by the U.S. Department of Energy (DOE), Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office (HFTO) under the auspices of the Electrocatalysis Consortium (ElectroCat 2.0). Argonne is managed for the U.S Department of Energy by the University of Chicago Argonne, LLC, under Contract DE-AC-02-06CH11357. 1. McCrory, CCL; Jung, S; Peters, JC; Jaramillo, TF. Benchmarking Heterogeneous Electrocatalysts for the Oxygen Evolution Reaction. J. Am. Chem. Soc. 2013, 135, 16977–16987.2. Sarkar R, Farghaly AA, Arachchige IU. Oxidative Self-Assembly of Au/Ag/Pt Alloy Nanoparticles into High-Surface Area, Mesoporous, and Conductive Aerogels for Methanol Electro-oxidation. Chemistry of Materials. 2022, 34(13), 5874-87.3. Khalafallah D, Farghaly AA, Ouyang C, Huang W, Hong Z. Atomically dispersed Pt single sites and nanoengineered structural defects enable a high electrocatalytic activity and durability for hydrogen evolution reaction and overall urea electrolysis. Journal of Power Sources. 2023, 558, 232563.4. Onajah S, Sarkar R, Islam MS, Lalley M, Khan K, Demir M, Abdelhamid HN, Farghaly AA. Silica‐Derived Nanostructured Electrode Materials for ORR, OER, HER, CO2RR Electrocatalysis, and Energy Storage Applications: A Review. The Chemical Record. 2024, e202300234.

Proton exchange membrane‐based electrocatalytic systems for hydrogen production

AbstractHydrogen energy from electrocatalysis driven by sustainable energy has emerged as a solution against the background of carbon neutrality. Proton exchange membrane (PEM)‐based electrocatalytic systems represent a promising technology for hydrogen production, which is equipped to combine efficiently with intermittent electricity from renewable energy sources. In this review, PEM‐based electrocatalytic systems for H2 production are summarized systematically from low to high operating temperature systems. When the operating temperature is below 130°C, the representative device is a PEM water electrolyzer; its core components and respective functions, research status, and design strategies of key materials especially in electrocatalysts are presented and discussed. However, strong acidity, highly oxidative operating conditions, and the sluggish kinetics of the anode reaction of PEM water electrolyzers have limited their further development and shifted our attention to higher operating temperature PEM systems. Increasing the temperature of PEM‐based electrocatalytic systems can cause an increase in current density, accelerate reaction kinetics and gas transport and reduce the ohmic value, activation losses, ΔGH*, and power consumption. Moreover, further increasing the operating temperature (120–300°C) of PEM‐based devices endows various hydrogen carriers (e.g., methanol, ethanol, and ammonia) with electrolysis, offering a new opportunity to produce hydrogen using PEM‐based electrocatalytic systems. Finally, several future directions and prospects for developing PEM‐based electrocatalytic systems for H2 production are proposed through devoting more efforts to the key components of devices and reduction of costs.

Minimizing renewable hydrogen costs at producer's terminal gate with alkaline electrolyser, proton exchange membrane, and their co-installment: A regional case study in China

China leads in deploying large-scale alkaline (ALK) and proton exchange membrane (PEM) electrolysers for renewable hydrogen production. However, they are often overbuilt to handle intermittent renewable electricity (RE), leading to frequent system shutdowns, wasted capacity, or extensive investment. In this work, we propose a co-optimization solution in which ALK and PEM are collocated alongside hybrid RE supply from solar and wind energies. Implementing such a strategy could achieve the lowest hydrogen costs at producer's terminal gate, with production levelized costs of hydrogen (PLCOHs) down to 5.05, 4.13, 3.89, and 5.97 USD per kg respectively in south, north, west, and east regions of China. The co-optimization strategy, harnessing the combined strengths of ALK and PEM systems, efficiently minimizes hydrogen production costs while also presenting opportunities for the integration of advanced technologies into existing facilities.

Sustainable hydrogen production by integrating solar PV electrolyser and solar evacuated tube collector with hybrid nanoparticles enhanced PCM

The investigation is motivated to analyze the influence of Phase change material (PCM), nano PCMs, and hybrid Nano PCM in sustainable hydrogen production systems. An emerging and highly effective method for hydrogen production involves the use of proton exchange membrane (PEM) technology, which separates water into its constituent parts through electrolysis. Its susceptibility to performance deterioration over time, however, demandsroutine maintenance and component replacement, which negatively impacts operational effectiveness and cost-effectiveness. In this study, the PEM system for electricity and water heating was integrated with the evacuated tube collector and photovoltaic panel to produce hydrogen. Additionally, hybrid Al2O3 and SiO2 nanoparticles with a combined concentration of 0.1 % in equal shares improved the thermal characteristics of PCM in heat exchangers. The research result shows that the heat exchanger of the ETSC circuit with the hybrid nanoparticles enhanced PCM demonstrated improved thermal performance as well as increased hydrogen production. With hybrid nanoparticles enhanced PCM in the heat exchanger, the maximum energy and electrical energy were observed as246.5 kWh and 44.7 kWh, respectively. The ETSC efficiency, electrical efficiency, and PEM electrolyser efficiency reached their highest points at 93.1 %, 15.5 %, and 39.2 %, respectively. Furthermore, hybrid nanoparticle-enhanced PCM produces an average of 25.9 g of hydrogen.

Development of Fe-Doped Ni2P-POx Electrocatalyst for Oxygen Evolution Reaction

Water electrolysis is extensively researched as a next-generation energy storage method to overcome the intermittency of renewable energy. Electricity generated from renewable sources such as solar and wind power can be converted into pure green hydrogen through water electrolysis. Despite the potential of green hydrogen as a renewable energy storage/carrier medium, the high overpotential resulting from the slow kinetics of oxygen evolution reaction (OER) and the use of expensive noble metals make cost-competitive hydrogen production a significant challenge. Anion exchange membrane water electrolysis (AEMWE) is one method for hydrogen production, offering economic advantages over proton exchange membrane systems as it allows for the use of relatively inexpensive transition metal catalysts like Ni, Fe, and Co due to its alkaline environment.Nickel phosphide (Ni2P)-based catalysts have emerged as highly promising candidates to accelerate the electrocatalytic OER. In particular, the introduction of Fe into Ni2P has been found to induce charge transfer, optimizing the electronic structure and accelerating the OER process. OER catalysts based on transition metal phosphides often exhibit a core-shell structure with phosphide at the core and oxide at the shell during OER measurements. This core-shell structure enhances OER performance through the oxide shell, complementing the deficient electrical conductivity of the phosphide core, resulting in superior catalytic activity and durability. From this perspective, transition metal phosphates are also being studied as electrocatalysts for OER. Phosphates, such as PO3 -, not only promote oxygen adsorbate adsorption but also induce a distorted local metal center geometry that favors OH- adsorption and further oxidation.To address these challenges, this study develops a facile and scalable synthesis of iron-doped nickel phosphide-phosphate (Fe-doped Ni2P-POx) nano-hybrid system as a superior noble-metal free OER powder-catalyst. The utilization of self-filling and pyrolysis approaches facilitates economically viable production of the highly porous phosphide catalyst with a high specific surface area and rough surfaces. X-ray diffractometer, X-ray photoelectron spectroscopy, and electron paramagnetic resonance elucidates the electronic structure modulation, resulting in phosphide-phosphate nano-hybrid structures. Consequently, the catalyst demonstrates excellent OER activity in 1 M KOH, with a significantly low overpotential of 283 mV at 20 mA cm-2, a small Tafel slope of 28.4 mV dec-1, and a superior exchange current density of 8.22 mA cm-2, surpassing state-of-the-art PGM catalysts. Furthermore, its durability over 20 hours indicates its excellent stability, mass transport properties, and mechanical robustness in alkaline media, underscoring its potential as an efficient OER catalyst to facilitate electrocatalytic hydrogen production. Figure 1

(Invited) Comparing and Contrasting the Advantages and Challenges of Catalysts for Low Temperature AEM, AEL, and PEM Electrolysis

Electrolysis has been promoted as a critical route to enabling green hydrogen and a broader US Department of Energy supported H2@Scale vision enabling a clean, economic and sustainable energy system.1 Low temperature electrolysis offers advantages over high temperature electrolysis in high temperature materials challenges, limited intermittency capabilities, thermal integration, lower manufacturing and technology readiness, steam conversion and separation challenges.2 Within low temperature electrolysis anion exchange membrane (AEM), (liquid) alkaline (AEL) and proton exchange membrane (PEM) electrolysis are the three primary electrolysis technologies being investigated.These electrolysis environments are different and the catalyst materials they employ, and the cost, natural abundance, performance, and durability limitations are all different. These factors have a significant impact on the research focus and needs for each of these competing technologies. This presentation will explore catalysis in each one of these systems and compare critical limitations of each.The PEM system depends on Ir for anode (OER) catalysis. Ir is expensive and one of the least abundant elements in the earth’s crust. While earth abundance of Ir may is a potential concern for projections of electrolysis needs,3,4 the ability to thrift Ir more efficiently and achieve improved durability are critical for achieving hydrogen cost targets. Specific features impacting the cost, performance and durability trade-offs of Ir in PEM electrolysis will be discussed in terms of hydrogen levelized costs and the research advances necessary to have a positive impact on PEM electrolyzers.AEM and AEL electrolysis are distinct in terms of the concentration of supporting (KOH) electrolytes being investigated and the types of electrodes typically employed. AEM electrolyzers typically work at 1M KOH concentrations or below and employ thin film electrodes with alkaline ionomer as a parallel to most PEM designs. AEL electrolyzers typically operate at high (30 wt% KOH) concentrations and consist of electrodes deposited onto metal substrates rather than deposited as a thin film onto the membrane/separator. The materials sets and some of the performance and durability challenges of each of these systems are similar. They also have challenges at both the anode and cathode, where as PEM cathodes operate highly efficiently and durably with low loadings of Pt. The primary advantage of alkaline systems is the ability to enable highly earth abundant electrocatalysis, but challenges remain for performance and durability tradeoffs. These aspects as well as their implications for hydrogen levelized cost will be presented along with target research needs. https://www.energy.gov/eere/fuelcells/h2scale.Alex Badgett, Mark Ruth, Bryan Pivovar, “Economic considerations for hydrogen production with a focus on polymer electrolyte membrane electrolysis,” Electrochemical Power Sources: Fundamentals, Systems, and Applications, 2022, 327-364.Cortney Mittelsteadt, Esben Sorensen, and Qingying Jia, Ir Strangelove, or How to Learn to Stop Worrying and Love the PEM Water Electrolysis Energy Fuels 2023, 37, 17, 12558–12569.Mark Clapp, Christopher M. Zalitis, Margery Ryan, Perspectives on current and future iridium demand and iridium oxide catalysts for PEM water electrolysis, Catalysis Today 420 (2023) 114140.

Integrated assessment of green hydrogen production in California: Life cycle Greenhouse gas Emissions, Techno-Economic Feasibility, and resource variability

This study explores green hydrogen production, focusing on life cycle assessment (LCA) and techno-economic feasibility; specifically, life cycle greenhouse gas emissions and hydrogen production cost. Existing literature lacks a comprehensive exploration of the impact of solar and wind resource variations, ambient conditions, and proton exchange membrane (PEM) electrolyzer sizing on the carbon intensity (CI) and hydrogen production cost. This work explores the relationship between the performance of photovoltaic (PV) and wind systems and the CI of renewable electricity in the U.S. Secondly, this study incorporates the hourly variations in solar and wind resources to assess the variation in hydrogen CI and production costs across California. The study examines how reductions in PEM and Renewable Energy Systems (RES) costs, technological advancements, and the inclusion of co-products’ carbon dioxide equivalent (CO2eq) credits and revenues impact hydrogen CI and production costs. Wind-based systems consistently demonstrate lower CI (0.35 − 1.9 kg CO2eq/kg H2) except for the central regions (CI can reach up to 4.34 kg CO2eq/kg H2), with geographical variations larger than solar-based systems (1.58 − 2.95 kg CO2eq/kg H2). Similar trends are observed for the hydrogen production cost which varies between 1.5 and 15 USD/kg H2 for wind-based systems and between 3.0 and 5.2 USD/kg H2 for the PV-based systems. This study highlights the importance of optimal sizing of PEM electrolyzer to maximize its utilization for hydrogen production and the use of hourly-based models to assess the CI and production costs of hydrogen. Additionally, the geographical variation in the renewable energy resources and the ambient conditions are important factors that affect the hydrogen cost and the CI of both renewable electricity and green hydrogen.

Hydrogen production by water electrolysis technologies: A review

Hydrogen as an energy source has been identified as an optimal pathway for mitigating climate change by combining renewable electricity with water electrolysis systems. Proton exchange membrane (PEM) technology has received a substantial amount of attention because of its ability to efficiently produce high-purity hydrogen while minimising challenges associated with handling and maintenance. Another hydrogen generation technology, alkaline water electrolysis (AWE), has been widely used in commercial hydrogen production applications. Anion exchange membrane (AEM) technology can produce hydrogen at relatively low costs because the noble metal catalysts used in PEM and AWE systems are replaced with conventional low-cost electrocatalysts. Solid oxide electrolyzer cell (SOEC) technology is another electrolysis technology for producing hydrogen at relatively high conversion efficiencies, low cost, and with low associated emissions. However, the operating temperatures of SOECs are high which necessitates long startup times. This review addresses the current state of technologies capable of using impure water in water electrolysis systems. Commercially available water electrolysis systems were extensively discussed and compared. The technical barriers of hydrogen production by PEM and AEM were also investigated. Furthermore, commercial PEM stack electrolyzer performance was evaluated using artificial river water (soft water). An integrated system approach was recommended for meeting the power and pure water demands using reversible seawater by combining renewable electricity, water electrolysis, and fuel cells. AEM performance was considered to be low, requiring further developments to enhance the membrane's lifetime.

(Invited) Techno-Economic Analysis on Near-Term and Future Projections of Levelized Cost of Hydrogen for Low-Temperature Water Electrolysis Technologies

Hydrogen is seen as a potential energy intermediary between renewable energy sources and end-use applications including transportation, power, and industrial feedstocks. Core to this approach is low-cost hydrogen generation via water electrolysis. Significant research has been undertaken to improve the electrolysis stack technology, including enhancements in electrical efficiency, materials degradation, and total stack cost. However, relative to the total cost of installing an electrolysis plant, the stack contributes <50% of the initial capital investment. Therefore, from an electrolysis project perspective, the mechanical balance of plant and electrical systems required to operate the plant are equally important to understand.To explore the near-term and future cost projection for hydrogen production via electrolysis, Strategic Analysis, Inc. (SA) has developed a bottom-up project cost model for Alkaline, Proton Exchange Membrane (PEM), and Anion Exchange Membrane (AEM) electrolysis technologies. This project cost model incorporates: 1) Stack cost, derived from a Design for Manufacturing and Assembly (DFMA) process-based cost model developed by SA, 2) mechanical balance of plant, including process equipment, piping, valves, and instrumentation, derived from equipment quotes, scaling, database values, and Aspen estimates; 3) electrical balance of plant, including wiring, rectification, and electrical infrastructure upgrades, derived from time and material cost correlations; 4) Site Preparation, focused on green field installation; and 5) Construction Overhead, including engineering, procurement, and construction (EPC) costs and project contingency. The SA project cost model is fed into a Levelized Cost of Hydrogen (LCOH) model that accounts for electricity and water consumption, in addition to other operating costs, including labor, maintenance, and stack replacements.The SA project cost model and the LCOH model were used to conceptualize electrolysis system sizes from 100 MW to 1 GW for Alkaline, PEM, and AEM electrolysis systems. From a project perspective, electricity costs contribute 50-80% to the LCOH while capital and maintenance costs contribute the remaining 20-50% to the LCOH. Improvements in stack performance and cost offer incremental improvements in LCOH; however, larger reductions in hydrogen cost will only be possible through optimization of the stack cell voltage and operating current density in conjunction with reductions in net electricity price through integration with low-cost, probably renewable, electricity.Results from SA’s polarization performance optimization model show that lower cost Alkaline stacks, having somewhat lower performance (than PEM), tend to optimize at lower current densities leading to a larger stack active area, and benefit from low operational voltage to obtain higher conversion efficiencies. Higher cost PEM stacks with higher performance (than Alkaline stacks) tend to optimize at higher current densities to reduce the size/capital cost of the stacks and can afford a lower stack efficiency. Multivariable sensitivity analyses show the statistical variation in capital cost leading to the most likely range in LCOH for each technology. The results of this study provide guidance on where the largest incremental reductions in LCOH can be achieved on a project basis.

Modelling of a Proton-Exchange Membrane Electrolysis Cell with Liquid-Fed Cathode

Conventional proton-exchange membrane (PEM) water electrolysers use much thicker membranes (>175 µm) than their PEM fuel cell counterparts (<25 µm), which reduces hydrogen crossover but also reduces electrolyzer efficiency due to the increased Ohmic resistance1. Reduction of hydrogen crossover is critical in conventional systems to avoid buildup of hydrogen in the anode above the lower explosive limit. Due to the use of liquid water at the anode in conventional systems, the anode cannot be flushed with air or an inert gas to reduce the hydrogen concentration.If the liquid water supply is moved to the cathode, the anode can be easily purged with air, reducing the safety concern related to hydrogen crossover. Proof-of-concept experiments2 have demonstrated the viability of this approach, but many open questions remain regarding the interplay between water transport, water consumption, membrane hydration, and cell performance, as well as understanding what components and properties are most important in improving the efficiency of such a device.In this work, a framework for modelling of PEM electrolysis cells will be outlined, with special attention to wet and dry anode conditions. The model will be used to provide guidance for optimizing system performance while contributing to understanding of local processes inside an electrolysis cell such as water transport, heat generation, reaction distribution, and bubble formation. We study the impact of various design and operational choices, such as membrane thicknesses, PTL structure, air feed humidity, and differential pressure operation, on the rate of water transport from cathode to anode and on overall cell polarization performance. Using these results, we provide design recommendations for PEM electrolysers with liquid-fed cathodes. Finally, progress towards an open-source implementation of this model will be discussed.This work has been performed within the HOPE (Revolutionizing Green Hydrogen Production with Next Generation PEM Water Electrolyser Electrodes) and HYSTACK (Low cost, high efficiency PEM electrolyser stack) projects financially supported by the Research Council of Norway under project numbers 325873 and 321466, respectively. Ayers, K. et al. Perspectives on Low-Temperature Electrolysis and Potential for Renewable Hydrogen at Scale. Annu. Rev. Chem. Biomol. Eng. 10, 219–239 (2019).Barnett, A. O. & Thomassen, M. S. Method for producing hydrogen in a PEM water electrolyser system, PEM water electrolyser cell, stack and system. Patent No.: WO 2019/009732. EP3649276B1. US11408081B2.

LMI-based Model Predictive Control Design for Supply Manifold Pressure Improvement of Proton Exchange Membrane Fuel Cell realized through Additive Manufacturing

The fuel cell is one of the renewable energy sources and proton exchange membrane (PEM) is the most common and widely used type. With the aim of increasing efficiency, this article first presents a developed PEM fuel cell with additive manufacturing (AM) process. Then, the nonlinear dynamic model describing the behaviour of the AM-based PEM cell is described, and considering the general working class, a new control method for adjusting the pressure of the supply manifold is presented. The planned control method is a combination of model predictive and LMI approaches and in addition to guaranteeing the stability of the closed loop system, it is able to adjust the pressure of the supply manifold and guarantee the optimal operation of the PEM system developed by the additive manufacturing process. The results of simulation and comparison in the MATLAB environment show the efficiency of the proposed control method in meeting the control objectives and improving the transient and permanent response.

Additive manufacturing for Proton Exchange Membrane (PEM) hydrogen technologies: merits, challenges, and prospects

With the growing demand for green technologies, hydrogen energy devices, such as Proton Exchange Membrane (PEM) fuel cells and water electrolysers, have received accelerated developments. However, the materials and manufacturing cost of these technologies are still relatively expensive which impedes their widespread commercialization. Additive Manufacturing (AM), commonly termed 3D Printing (3DP), with its advanced capabilities, could be a potential pathway to solve the fabrication challenges of PEM parts. Herein, in this paper, the research studies on the novel AM fabrication methods of PEM components are thoroughly reviewed and analysed. The key performance properties, such as corrosion and hydrogen embrittlement resistance, of the additively manufactured materials in the PEM working environment are discussed to emphasise their reliability for the PEM systems. Additionally, the major challenges and required future developments of AM technologies to unlock their full potential for PEM fabrication are identified. This paper provides insights from the latest research developments on the significance of advanced manufacturing technologies in developing sustainable energy systems to address the global energy challenges and climate change effects.

Design of proton exchange membranes with high durability for fuel cells: From the perspective of machine learning

Proton exchange membranes (PEMs)（） with high chemical durability have been generally researched in recent years. Free radical scavengers such as ceria can significantly suppress the chemical degradation of proton exchange membranes when added to proton exchange membranes. However, proton conductivity may decline in the presence of ceria. Thus, a trade-off between performance and durability in ceria-containing membranes emerges. To address this challenge, we developed a novel machine learning methodology called SPARK (Smart Prediction of Advanced Research on PEMs using Knowledge-based machine learning) to quickly predict the performance and durability of proton exchange membranes in fuel cell applications with high precision. Moreover, with the definition of the mixed index, the performance and durability were coupled, and the trade-off of performance and durability could be easily made. The SPARK methodology not only streamlines the design process for ceria-containing proton exchange membranes but also has broader implications for the development of other proton exchange membrane systems.

Proton Exchange Membrane Electrolysis Performance Targets for Achieving 2050 Expansion Goals Constrained by Iridium Supply

As demand for hydrogen electrolysis increases with the renewable energy transition, it is critical to ensure that the supply of required resources for these technologies is sufficient to match demand. Several studies have set forth projections for H2 production targets to achieve net-zero emissions by mid-century, where proton exchange membrane (PEM) electrolyzers feature prominently. As compared to other commercially available electrolyzers, PEM systems exhibit high current densities that favor flexible operation to utilize intermittent renewable energy sources but rely on relatively scarce iridium (Ir) for catalysis. In this work, we model the supply of Ir resources available for PEM electrolysis and compare it to the Ir required to meet plausible H2 production targets for 2030 and 2050. In order for Ir supply to be sufficient for 2030 H2 production targets, significant improvement in average operational current density or Ir loading would be required compared to today’s averages of 2 A/cm2 and 2 mg/cm2, respectively. By 2050, current technology may be sufficient to meet the lower end of H2 production targets (83 Mt), with modest technological advances needed in case H2 demand exceeds these levels.

Development of Model-Based PEM Water Electrolysis HILS (Hardware-in-the-Loop Simulation) System for State Evaluation and Fault Detection

Hydrogen is attracting attention as a good energy-storage medium for renewable energy. Among hydrogen production technologies using renewable energy, water electrolysis is drawing attention as a key technology for green hydrogen production using renewable energy. In particular, polymeric electrolyte membrane water electrolysis systems have several advantages compared to other types of water electrolysis technologies, such as small size and mass, high efficiency, low operating temperature, and low power consumption. However, until now, proton-exchange membrane (PEM) water electrolysis systems have not been reliable. In this study, system failure diagnosis techniques were presented among the various methods for improving reliability. We developed PEM water electrolysis stack models and system models to predict the performance of the system and analyze the dynamic properties using MATLAB/Simulink® 2018a, which have been validated under various conditions. The developed dynamic characteristic simulation model applies hardware-in-the-loop simulation (HILS) technology to configure experimental devices to interact in real-time. The developed PEMWE HILS system accepts signals that control the system, operates the experimental setup and simulation model in real-time, and diagnoses the system’s failure based on the results.

Enhancing reliability and lifespan of PEM fuel cells through neural network-based fault detection and classification

In order to maximise fuel cell reliability of operation and useful life span, an accurate online health assessment of the fuel cell system is essential. Existing algorithms for fault detection in fuel cell systems are based on sensing elements, control methods, and statistical/probabilistic models. In this paper, an artificial neural network (ANN) will be developed to detect and classify faults in proton-exchange membrane (PEM) fuel cell systems. As the ANN model developed within the PEM system relies on the input and output current and voltage, additional sensing devices are not required within the system. Based on an experimental setup using a 3-kW fuel cell system, it was found that the proposed model was able to detect faults associated with the reduction/increase of fuel pressure, H2 consumption rate, and voltage regulation changes in the dc-dc converter with >90% accuracy. In the proposed model, historical data is required to train and validate the ANN algorithm, but after this is complete, no human intervention is required afterward.

Assessment of hydrogen production from waste heat using hybrid systems of Rankine cycle with proton exchange membrane/solid oxide electrolyzer

A techno-economic assessment of hydrogen production from waste heat using a proton exchange membrane (PEM) electrolyzer and solid oxide electrolyzer cell (SOEC) integrated separately with the Rankine cycle via two different hybrid systems is investigated. The two systems run via three available cement waste heats of temperatures 360 °C, 432 °C, and 780 °C with the same energy input. The waste heat is used to run the Rankine cycle for the power production required for the PEM electrolyzer system, while in the case of SOEC, a portion of waste heat energy is used to supply the electrolyzer with the necessary steam. Firstly, the best parameters; Rankine working fluid for the two systems and inlet water flow rate and bleeding ratio for the SOEC system are selected. Then, the performance of the two systems (Rankine efficiency, total system efficiency, hydrogen production rate, and economic and CO2 reduction) is investigated and compared. The results reveal that the two systems' performance is higher in the case of steam Rankine than organic, while a bleeding ratio of 1% is the best condition for the SOEC system. Rankine output power, total system efficiency, and hydrogen production rate rose with increasing waste heat temperature having the same energy. SOEC system produces higher hydrogen production and efficiency than the PEM system for all input waste heat conditions. SOEC can produce 36.9 kg/h of hydrogen with a total system efficiency of 23.8% at 780 °C compared with 27.4 kg/h and 14.45%, respectively, for the PEM system. The minimum hydrogen production cost of SOEC and PEM systems is 0.88 $/kg and 1.55 $/kg, respectively. The introduced systems reduce CO2 emissions annually by about 3077 tons.

Power quality improvement for 20 MW PEM water electrolysis system

Hydrogen is an important alternative as a clean fuel for industry and power-to-gas energy storage. The water electrolysis process is a promising technology in green hydrogen production where proton exchange membrane (PEM) technology has been keenly interested. Industrial large-scale PEM electrolyzers need a high current power supply. When connected to an alternating current (AC) source, high current power rectifiers are used to convert AC to DC. Currently, the most commonly used topology in large-scale PEM electrolysis systems is the thyristor-based topology due to its technology maturity and low cost. However, this topology presents several drawbacks in terms of power quality and consequently leads to higher stack-specific energy consumption (SEC) and additional losses. In the present research, we demonstrate the potential power quality improvement for a 20 MW PEM water electrolysis system by rectifier topology upgrade. Rather than traditional thyristor-based topology, a 3-phase interleaved buck rectifier topology is proposed. The new topology presents advantages on both AC and DC sides via a validated simulation model, which is built using MATLAB/Simulink and then validated with experimental data from an industrial 20 MW PEM water electrolyzer at Air Liquide's Bécancour plant. Results show a great improvement in terms of power factor, Total Harmonic Distortion (THD), and DC-current ripple reducing the total losses and the SEC of the PEM stack, especially under partial load. Towards a higher power efficiency, the proposed rectifier topology may be considered in the construction of future large-scale PEM systems.

Aerogel-Derived Fe-N-C Catalysts for Oxygen Electro-Reduction. Linking Their Pore Structure and PEMFC Performance

Iron-based catalysts are intensely investigated for application at the cathode of proton exchange membrane (PEM) and, more recently, of anion exchange membrane fuel cells (AEMFC). Besides optimising their kinetic activity toward the oxygen reduction reaction (ORR), the design and control of their pore structure plays a key role in achieving the highest possible performance in fuel cell. Fe-N-C catalysts derived from the metal-organic framework ZIF-8 are highly active but also mainly microporous, which can lead to mass-transport issues. The silica templating approach typically leads to slightly less active Fe-N-C catalysts, but featuring a combination of micropores and mesopores, which can facilitate mass-transport. Aerogel methods for the synthesis of Fe-N-C catalysts with a hierarchical pore size distribution has been hitherto under-investigated. In contrast to the silica templating method, it is more environmental friendly since no dissolution of a template is needed (no HF). However, highly active Fe-N-C catalysts prepared by aerogel method have not yet been reported in PEM system (even if promising results were recently obtained in rotating disk electrode [1-2]), and it is therefore also unclear if the hierarchical pore size distribution derived from this method is beneficial for improving the mass-transport properties of Fe-N-C cathodes.This presentation will first report the synthesis method and the key parameters investigated, such as the ratio of melamine to resorcinol, the nature and amount of the iron precursor, the addition of an additionnal N-rich ligand, on their ORR activity. The materials were characterized for their texture (N2 sorption, Hg porosimetry), Fe coordination (X-ray absorption and Mössbauer spectroscopy) and surface chemistry (XPS) and morphology. The most promising materials were investigated in PEMFC, for their initial power performance and durability. The results show that, by playing with these synthesis parameters, the aerogel method can yield highly active ORR catalysts (Figure 1), and can give a control on their hierarchical porosity, especially in tuning the mesoporous volume and the average pore width of mesopores. Most catalysts display an atomic dispersion of Fe, explaining their high ORR activity. The presentation will particularly discuss the link between the pore size distribution in this set of materials (micro, meso and macropores), and the mass-transport properties in PEMFC, under pure O2 or air at the cathode. Their durability will also be discussed, from accelerated stress tests performed in rotating disk electrode and/or PEMFC.Acknowledgments:This study was financially supported by the French National Research Agency under the project ANIMA (ANR-19-CE05-0039).