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Water electrolysers with closed and open electrochemical systems

Nature Materials volume 19, pages 1140–1150 (2020)Cite this article

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Abstract

Green hydrogen production using renewables-powered, low-temperature water electrolysers is crucial for rapidly decarbonizing the industrial sector and with it many chemical transformation processes. However, despite decades of research, advances at laboratory scale in terms of catalyst design and insights into underlying processes have not resulted in urgently needed improvements in water electrolyser performance or higher deployment rates. In light of recent developments in water electrolyser devices with modified architectures and designs integrating concepts from Li-ion or redox flow batteries, we discuss practical challenges hampering the scaling-up and large-scale deployment of water electrolysers. We highlight the role of device architectures and designs, and how engineering concepts deserve to be integrated into fundamental research to accelerate synergies between materials science and engineering, and also to achieve industry-scale deployment. New devices require benchmarking and assessment in terms of not only their performance metrics, but also their scalability and deployment potential.

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Fig. 1: Schematic illustrating closed versus open electrochemical systems.
Fig. 2: Schematic of set-ups used for performance characterization at the lab-scale and the pilot-scale/industry-scale.
Fig. 3: Cost aspects of WE systems.
Fig. 4: Architecture and design approaches and their implementation for emerging WEs.

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Article 27 October 2022

Arthur J. Shih, Mariana C. O. Monteiro, … Marc T. M. Koper

References

  1. Le Quéré, C. et al. Global carbon budget 2018. Earth Syst. Sci. Data 10, 2141–2194 (2018).

    Google Scholar 

  2. Global Energy Transformation: A Roadmap to 2050 (IRENA, 2019).

  3. Global Energy and CO2 Status Report (IRENA, 2017).

  4. Energy Prices and Cost in Europe (European Commission, 2019).

  5. Winter, M., Barnett, B. & Xu, K. Before Li ion batteries. Chem. Rev. 118, 11433–11456 (2018).

    CAS  Google Scholar 

  6. Curry, C. Lithium-Ion Battery Costs and Market (Bloomberg New Energy Finance, 2017).

  7. Pillot, C. Impact of the xEV Market Growth on Lithium-Ion Batteries and Raw Materials Supply 2019–2030 (Avicenne Energy, 2020).

  8. The Future of Hydrogen (IENA, 2019).

  9. Hydrogen: A Renewable Energy Perspective (IRENA, 2019).

  10. van Hulst, N. The clean hydrogen future has already begun. IEA https://www.iea.org/newsroom/news/2019/april/the-clean-hydrogen-future-has-already-begun.html (2019).

  11. Gül, T., Fernandez Pales, A. & Paoli, L. Batteries and hydrogen technology: keys for a clean energy future. IEA https://www.iea.org/articles/batteries-and-hydrogen-technology-keys-for-a-clean-energy-future (2020).

  12. Nørskov, J. K. et al. Research Needs Towards Sustainable Production of Fuels and Chemicals (ENERGY-X, 2019).

  13. The Battolyser https://battolyser.com (2019).

  14. Weninger, B. M. H. & Mulder, F. M. Renewable hydrogen and electricity dispatch with multiple Ni–Fe electrode storage. ACS Energy Lett. 4, 567–571 (2019).

    CAS  Google Scholar 

  15. Bernt, M. et al. Current challenges in catalyst development for PEM water electrolyzers. Chem. Ing. Tech. 90, 31–39 (2020).

    Google Scholar 

  16. Faustini, M. et al. Hierarchically structured ultraporous iridium-based materials: a novel catalyst architecture for proton exchange membrane water electrolyzers. Adv. Energy Mater. 9, 1802136 (2019).

    Google Scholar 

  17. Wu, T. et al. Iron-facilitated dynamic active-site generation on spinel CoAl2O4 with self-termination of surface reconstruction for water oxidation. Nat. Catal. 2, 763–772 (2019).

    CAS  Google Scholar 

  18. King, L. A. et al. A non-precious metal hydrogen catalyst in a commercial polymer electrolyte membrane electrolyser. Nat. Nanotechnol. 14, 1071–1074 (2019).

    CAS  Google Scholar 

  19. Seh, Z. W. et al. Combining theory and experiment in electrocatalysis: insights into materials design. Science 355, eaad4998 (2017).

    Google Scholar 

  20. Kibsgaard, J. & Chorkendorff, I. Considerations for the scaling-up of water splitting catalysts. Nat. Energy 4, 430–433 (2019).

    Google Scholar 

  21. Inaba, M. et al. Benchmarking high surface area electrocatalysts in a gas diffusion electrode: measurement of oxygen reduction activities under realistic conditions. Energy Environ. Sci. 11, 988–994 (2018).

    CAS  Google Scholar 

  22. Wei, C. et al. Recommended practices and benchmark activity for hydrogen and oxygen electrocatalysis in water splitting and fuel cells. Adv. Mater. 31, 1806296 (2019).

    Google Scholar 

  23. Suntivich, J., Gasteiger, H. A., Yabuuchi, N. & Shao-Horn, Y. Electrocatalytic measurement methodology of oxide catalysts using a thin-film rotating disk electrode. J. Electrochem. Soc. 157, B1263–B1268 (2010).

    CAS  Google Scholar 

  24. Debe, M. K. Electrocatalyst approaches and challenges for automotive fuel cells. Nature 486, 43–51 (2012).

    CAS  Google Scholar 

  25. Kroschel, M., Bonakdarpour, A., Kwan, J. T. H., Strasser, P. & Wilkinson, D. P. Analysis of oxygen evolving catalyst coated membranes with different current collectors using a new modified rotating disk electrode technique. Electrochim. Acta 317, 722–736 (2019).

    CAS  Google Scholar 

  26. Bender, G. et al. Initial approaches in benchmarking and round robin testing for proton exchange membrane water electrolyzers. Int. J. Hydrog. Energy 44, 9174–9187 (2019).

    CAS  Google Scholar 

  27. Ayers, K. Benchmarking Advanced Water Splitting Technologies: Best Practices in Materials Characterization (Energy Materials Network, 2019).

  28. Colli, A. N., Girault, H. H. & Battistel, A. Non-precious electrodes for practical alkaline water electrolysis. Materials 12, 1336 (2019).

    CAS  Google Scholar 

  29. Weiß, A. et al. Impact of intermittent operation on lifetime and performance of a PEM water electrolyzer. J. Electrochem. Soc. 166, F487–F497 (2019).

    Google Scholar 

  30. Debe, M. K. et al. Initial performance and durability of ultra-low loaded NSTF electrodes for PEM electrolyzers. J. Electrochem. Soc. 159, K165–K176 (2012).

    CAS  Google Scholar 

  31. Bock, R. et al. Measuring the thermal conductivity of membrane and porous transport layer in proton and anion exchange membrane water electrolyzers for temperature distribution modeling. Int. J. Hydrog. Energy 45, 1236–1254 (2019).

    Google Scholar 

  32. Wang, L. et al. Electrochemically converting carbon monoxide to liquid fuels by directing selectivity with electrode surface area. Nat. Catal. 2, 702–708 (2019).

    CAS  Google Scholar 

  33. Andersen, S. Z. et al. A rigorous electrochemical ammonia synthesis protocol with quantitative isotope measurements. Nature 570, 504–508 (2019).

    CAS  Google Scholar 

  34. Wakerley, D. et al. Bio-inspired hydrophobicity promotes CO2 reduction on a Cu surface. Nat. Mater. 18, 1222–1227 (2019).

    CAS  Google Scholar 

  35. Weng, L.-C., Bell, A. T. & Weber, A. Z. Modeling gas-diffusion electrodes for CO2 reduction. Phys. Chem. Chem. Phys. 20, 16973–16984 (2018).

    CAS  Google Scholar 

  36. Burdyny, T. & Smith, W. A. CO2 reduction on gas-diffusion electrodes and why catalytic performance must be assessed at commercially-relevant conditions. Energy Environ. Sci. 12, 1442–1453 (2019).

    CAS  Google Scholar 

  37. Mayyas, A. et al. Manufacturing Cost Analysis for Proton Exchange Membrane Water Electrolyzers (National Renewable Energy Laboratory, 2019).

  38. Fritz, K. E., Beaucage, P. A., Matsuoka, F., Wiesner, U. & Suntivich, J. Mesoporous titanium and niobium nitrides as conductive and stable electrocatalyst supports in acid environments. Chem. Commun. 53, 7250–7253 (2017).

    CAS  Google Scholar 

  39. Gago, A. S. et al. Protective coatings on stainless steel bipolar plates for proton exchange membrane (PEM) electrolysers. J. Power Sources 307, 815–825 (2016).

    CAS  Google Scholar 

  40. Ayers, K., Capuano, C. B. & Anderson, E. B. Recent advances in cell cost and efficiency for PEM-based water electrolysis. ECS Trans. 41, 15–22 (2012).

    CAS  Google Scholar 

  41. 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).

    CAS  Google Scholar 

  42. Bernt, M., Siebel, A. & Gasteiger, H. A. Analysis of voltage losses in PEM water electrolyzers with low platinum group metal loadings. J. Electrochem. Soc. 165, F305–F314 (2018).

    CAS  Google Scholar 

  43. Schmuch, R., Wagner, R., Hörpel, G., Placke, T. & Winter, M. Performance and cost of materials for lithium-based rechargeable automotive batteries. Nat. Energy 3, 267–278 (2018).

    CAS  Google Scholar 

  44. Pillot, C. The Rechargeable Battery Market and Main Trends 2018–2030 (Avicenne Energy, 2019).

  45. Lehner, M., Tichler, R., Steinmüller, H. & Koppe, M. Power-to-Gas: Technology and Business Models 19–39 (Springer, 2014).

  46. Yanagi, H. & Fukuta, K. Anion exchange membrane and ionomer for alkaline membrane fuel cells (AMFCs). ECS Trans. 16, 257–262 (2008).

    CAS  Google Scholar 

  47. Varcoe, J. R. et al. Anion-exchange membranes in electrochemical energy systems. Energy Environ. Sci. 7, 3135–3191 (2014).

    CAS  Google Scholar 

  48. Abbasi, R. et al. A roadmap to low-cost hydrogen with hydroxide exchange membrane electrolyzers. Adv. Mater. 31, 1805876 (2019).

    Google Scholar 

  49. Whiston, M. M. et al. Expert assessments of the cost and expected future performance of proton exchange membrane fuel cells for vehicles. Proc. Natl Acad. Sci. USA 116, 4899–4904 (2019).

    CAS  Google Scholar 

  50. Energy Technology Perspectives 2020: Special Report on Clean Energy Innovation (IEA, 2020).

  51. You, B. & Sun, Y. Innovative strategies for electrocatalytic water splitting. Acc. Chem. Res. 51, 1571–1580 (2018).

    CAS  Google Scholar 

  52. Esposito, D. V. Membraneless electrolyzers for low-cost hydrogen production in a renewable energy future. Joule 1, 651–658 (2017).

    CAS  Google Scholar 

  53. H. Hashemi, S. M., Modestino, M. A. & Psaltis, D. A membrane-less electrolyzer for hydrogen production across the pH scale. Energy Environ. Sci. 8, 2003–2009 (2015).

    CAS  Google Scholar 

  54. Kato, T., Kubota, M., Kobayashi, N. & Suzuoki, Y. Effective utilization of by-product oxygen from electrolysis hydrogen production. Energy 30, 2580–2595 (2005).

    CAS  Google Scholar 

  55. O’Neil, G. D., Christian, C. D., Brown, D. E. & Esposito, D. V. Hydrogen production with a simple and scalable membraneless electrolyzer. J. Electrochem. Soc. 163, F3012–F3019 (2016).

    Google Scholar 

  56. Davis, J. T., Qi, J., Fan, X., Bui, J. C. & Esposito, D. V. Floating membraneless PV-electrolyzer based on buoyancy-driven product separation. Int. J. Hydrog. Energy 43, 1224–1238 (2018).

    CAS  Google Scholar 

  57. Hashemi, S. M. H. et al. A versatile and membrane-less electrochemical reactor for the electrolysis of water and brine. Energy Environ. Sci. 12, 1592–1604 (2019).

    Google Scholar 

  58. Symes, M. D. & Cronin, L. Decoupling hydrogen and oxygen evolution during electrolytic water splitting using an electron-coupled-proton buffer. Nat. Chem. 5, 403–409 (2013).

    CAS  Google Scholar 

  59. Rausch, B., Symes, M. D., Chisholm, G. & Cronin, L. Decoupled catalytic hydrogen evolution from a molecular metal oxide redox mediator in water splitting. Science 345, 1326–1330 (2014).

    CAS  Google Scholar 

  60. Mulder, F. M., Weninger, B. M. H., Middelkoop, J., Ooms, F. G. B. & Schreuders, H. Efficient electricity storage with a battolyser, an integrated Ni-Fe battery and electrolyser. Energy Environ. Sci. 10, 756–764 (2017).

    CAS  Google Scholar 

  61. Chen, L., Dong, X., Wang, Y. & Xia, Y. Separating hydrogen and oxygen evolution in alkaline water electrolysis using nickel hydroxide. Nat. Commun. 7, 11741 (2016).

    CAS  Google Scholar 

  62. Amstutz, V. et al. Renewable hydrogen generation from a dual-circuit redox flow battery. Energy Environ. Sci. 7, 2350–2358 (2014).

    CAS  Google Scholar 

  63. Peljo, P. et al. All-vanadium dual circuit redox flow battery for renewable hydrogen generation and desulfurisation. Green. Chem. 19, 1785–1797 (2016).

    Google Scholar 

  64. Landman, A. et al. Photoelectrochemical water splitting in separate oxygen and hydrogen cells. Nat. Mater. 16, 646–652 (2017).

    CAS  Google Scholar 

  65. Gillespie, M. I., Van Der Merwe, F. & Kriek, R. J. Performance evaluation of a membraneless divergent electrode-flow-through (DEFT) alkaline electrolyser based on optimisation of electrolytic flow and electrode gap. J. Power Sources 293, 228–235 (2015).

    CAS  Google Scholar 

  66. Gillespie, M. I. & Kriek, R. J. Hydrogen production from a rectangular horizontal filter press Divergent Electrode-Flow-Through (DEFTTM) alkaline electrolysis stack. J. Power Sources 372, 252–259 (2017).

    CAS  Google Scholar 

  67. Dotan, H. et al. Decoupled hydrogen and oxygen evolution by a two-step electrochemical–chemical cycle for efficient overall water splitting. Nat. Energy 4, 786–795 (2019).

    CAS  Google Scholar 

  68. Tsotridis, G. & Pilenga, A. EU Harmonised Terminology for Low Temperature Water Electrolysis for Energy Storage Applications (Publications Office of the European Union, 2018).

  69. Palacín, M. R. & De Guibert, A. Batteries: Why do batteries fail? Science 351, 1253292 (2016).

    Google Scholar 

  70. Battolyser B. V. https://www.battolyserbv.com (2020).

  71. ERGOSUP https://www.ergosup.com/electrolyseur-sous-pression/ (2020).

  72. Hydrox Holdings Ltd https://hydroxholdings.co.za (2020).

  73. Wilson, A., Kleen, G. & Papageorgopoulos, D. Fuel Cell System Cost - 2017 (US Department of Energy, 2017).

  74. Slowik, P., Pavlenko, N. & Lutsey, N. Assessment of Next-Generation Electric Vehicle Technologies (International Council on Clean Transportation, 2016).

  75. Fumatech https://www.fumatech.com (2020).

  76. Dioxide Materials https://dioxidematerials.com (2020).

  77. Pavel, C. C. et al. Highly efficient platinum group metal free based membrane-electrode assembly for anion exchange membrane water electrolysis. Angew. Chem. Int. Ed. 126, 1402–1405 (2014).

    Google Scholar 

  78. Enapter https://www.enapter.com/ (2020).

  79. Parrondo, J. et al. Degradation of anion exchange membranes used for hydrogen production by ultrapure water electrolysis. RSC Adv. 4, 9875–9879 (2014).

    CAS  Google Scholar 

  80. Gardner, G. et al. Structural basis for differing electrocatalytic water oxidation by the cubic, layered and spinel forms of lithium cobalt oxides. Energy Environ. Sci. 9, 184–192 (2016).

    CAS  Google Scholar 

  81. Proton OnSite https://www.protononsite.com/ (2020).

  82. Yoon, Y., Yan, B. & Surendranath, Y. Suppressing ion transfer enables versatile measurements of electrochemical surface area for intrinsic activity comparisons. J. Am. Chem. Soc. 140, 2397–2400 (2018).

    CAS  Google Scholar 

  83. Dubouis, N. & Grimaud, A. The hydrogen evolution reaction: From material to interfacial descriptors. Chem. Sci. 10, 9165–9181 (2019).

    CAS  Google Scholar 

  84. Garcia, A. C., Touzalin, T., Nieuwland, C., Perini, N. & Koper, M. T. M. Enhancement of oxygen evolution activity of nickel oxyhydroxide by electrolyte alkali cations. Angew. Chem. Int. Ed. 58, 12999–13003 (2019).

    CAS  Google Scholar 

  85. Babic, U., Suermann, M., Büchi, F. N., Gubler, L. & Schmidt, T. J. Critical review—identifying critical gaps for polymer electrolyte water electrolysis development. J. Electrochem. Soc. 164, F387–F399 (2017).

    CAS  Google Scholar 

  86. Harrison, K. & Levene, J. I. in Solar Hydrogen Generation: Toward a Renewable Energy Future (eds Rajeshwar, K., McConnell, R. & Licht, S.) 41–63 (Springer, 2008).

  87. Bertuccioli, L. et al. Development of Water Electrolysis in the European Union (Fuel Cells and Hydrogen Joint Undertaking, 2014).

  88. Coutanceau, C., Baranton, S. & Audichon, T. Hydrogen Electrochemical Production 17–62 (Academic Press, 2017).

  89. Guillet, N. & Millet, P. in Hydrogen Production (ed. Godula‐Jopek, A.) 117–166 (Wiley, 2015).

  90. Miller, H. A. et al. Green hydrogen from anion exchange membrane water electrolysis: a review of recent developments in critical materials and operating conditions. Sustain. Energy Fuels 4, 2114–2133 (2020).

    CAS  Google Scholar 

  91. Frankel, D., Kane, S. & Tryggestad, C. The new rules of competition in energy storage. McKinsey https://www.mckinsey.com/industries/electric-power-and-natural-gas/our-insights/the-new-rules-of-competition-in-energy-storage (2018).

  92. Mongird, K. et al. Energy Storage Technology and Cost Characterization Report (US Department of Energy, 2019).

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Acknowledgements

The authors acknowledge financial support from the ANR MIDWAY project (project ID: ANR-17-CE05-0008), from the French national network ‘Réseau sur le Stockage Electrochimique de l’Energie’ (RS2E) FR CNRS 3459 and from the Laboratory of Excellence programme STORE-EX (ANR 10-LABX-0076). They thank N. Dubouis for his contribution to Fig. 2b; C. Ferchaud for useful discussions regarding hydrogen pressurization; and J.-M. Tarascon, N. Dubouis, R. Dugas and B. M. Gallant for critical examination of the manuscript in its early stage.

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Authors and Affiliations

  1. Chimie du Solide et de l’Energie, Collège de France, UMR 8260, Paris, France

    Marie Francine Lagadec & Alexis Grimaud

  2. Réseau sur le Stockage Electrochimique de l’Energie (RS2E), CNRS FR3459, Amiens, France

    Alexis Grimaud

  3. Sorbonne Université, Paris, France

    Alexis Grimaud

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M.F.L. and A.G. contributed equally to conceiving, developing and writing the manuscript.

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Correspondence to Marie Francine Lagadec or Alexis Grimaud.

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Extended data

Extended Data Fig. 1 Low-temperature water electrolyser architectures and designs.

a, Alkaline water electrolyser. b, Proton exchange membrane water electrolyser. c, Anion exchange membrane water electrolyser. The components and commonly used materials or commercial products of each electrolyser design are listed at the top and at the bottom of the schematics, respectively.

Extended Data Fig. 2

Physical properties of proton exchange membrane and anion exchange membrane water electrolyser components which impact water electrolyser performance and stack cost.

Extended Data Fig. 3

Design and performance parameters of state-of-the-art alkaline, proton exchange membrane and anion exchange membrane water electrolysers.45,68,86,87,88,89,90.

Extended Data Fig. 4 Key information and assumptions for cost calculations used in ref. 37.

Mayyas et al. classify catalyst coated membranes (CCMs) and porous transport layers (PTLs) as membrane electrode assemblies (MEAs), which are held in place by a frame. In our definition, MEAs consist of a membrane and the electrodes.

Extended Data Fig. 5

Data extracted from ref. 37 using WebPlotDigitizer as plotted in Fig. 3a-c.

Extended Data Fig. 6 Data for Li-ion battery packs (ref. 74) and proton exchange membrane water electrolyser (ref. 37) and fuel cell (ref. 73) stacks and systems as plotted in Fig. 3d.

The data of references74 and37 were extracted using WebPlotDigitizer. For PEM fuel cell (PEMFC) and water electrolyser (PEMWE) systems, the balance of plant (BOP) cost includes cost associated with power supply, water circulation and gas processing parts as well as other parts (see Fig. 3a and Extended Data Fig. 5 for PEMWE systems). As shown in this table, the BOP cost of PEMWEs makes up a larger fraction of the system cost compared to the one of PEMFCs; at current production rates (10 units per year for PEMWEs and several thousand units per year for PEMFCs), the BOP cost fraction is about 50-60% for PEMWEs and 35-50% for PEMFCs. This is in part due to the different power supply requirements for large-scale, on-site PEMWE applications and for specific mobile PEMFC applications. For the highest projected production rates (50k units per year for PEMWEs and 500k units per year for PEMFCs), the BOP cost is fairly constant for PEMWEs (60-75% of system cost depending on system size) and PEMFCs (reaching up to 60% of system cost). Li-ion batteries deviated from portable electronics applications require a battery management system (BMS). The BMS can be seen as the equivalent of balance of stack equipment and its cost amounts to ~10% of reported LIB pack cost. For large-scale applications, balance of system (BOS) equipment is required (for example, comprising climate control, containerisation, inverter, controller and controls)91. This BOS cost is not comprised in the pack cost as reported in this table, and would lead to an additional ~10% on top of pack cost.92 At a production rate of 100k units per year, Li-ion battery pack cost is projected to be 210 $/kWh; thus, we estimate a BOS cost of ~21 $/kWh and a total Li-ion system cost (including battery pack, BOS, power conversion systems, and construction and commissioning cost) to be in the order of up to twice the battery pack cost (that is, ~400 $/kWh) based on the values given in ref. 92.

Extended Data Fig. 7 Design parameters and performance characteristics for emerging water electrolysers14,53,55,56,57,58,59,60,61,62,63,64,65,66,67.

The listed values are recorded at room temperature (except for ref. 60: 30-40 °C, refs. 65,66: 70-80 °C and ref. 67: 25-95 °C). The studies marked in blue are shown in greater detail in Fig. 4b-c. Efficiency values are given for system efficiency (SE), Faradaic efficiency (FE), voltage efficiency (VE) and higher heating value efficiency (HHVE) of hydrogen.

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Lagadec, M.F., Grimaud, A. Water electrolysers with closed and open electrochemical systems. Nat. Mater. 19, 1140–1150 (2020). https://doi.org/10.1038/s41563-020-0788-3

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