Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

An operationally broadened alkaline water electrolyser enabled by highly stable poly(oxindole biphenylene) ion-solvating membranes

Nature Energy volume 9, pages 401–410 (2024)Cite this article

Subjects

Abstract

Ion-solvating membranes (ISMs) are an alternative to proton-exchange and anion-exchange membranes for use in water electrolysers. ISMs do not have fixed ionic groups in their structure but instead gain their ionic conductivity through the uptake of liquid electrolyte. Although in principle they could offer improved stability over anion-exchange membranes due to the absence of easily degradable anion-exchange groups, stability gains have been modest. Here we report poly(oxindole biphenylene)-based ISMs with highly stable oxindole/KOH complex ion pairs for use in water electrolysers. These ISMs exhibit promising alkaline stability at 80 °C with a negligible conductivity decay over more than 15,000 h and, thus, allow durable alkaline electrolysis over 2,500 h, even at elevated temperatures and high operating voltages of 2.3 V. Moreover, they show ultralow gas permeation and, thus, low transient response times (<1 s). They allow the use of non-precious-metal catalysts (Ni and Ni/Fe) and can be operated over a broad temperature range (−35 to 120 °C).

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: DFT calculation and alkaline stability of model compounds.
Fig. 2: Preparation and characterization of POBP-ISM.
Fig. 3: Properties and stability of POBP-ISMs.
Fig. 4: Polarization curves of AWE.
Fig. 5: Durability of POBP-ISM AWEs.

Similar content being viewed by others

Data availability

The authors declare that the data supporting the findings of this study are available within the paper, Supplementary Information and Source Data files. Further data beyond the immediate results presented here are available from the corresponding authors upon reasonable request. Source data are provided with this paper.

References

  1. Li, D. et al. Highly quaternized polystyrene ionomers for high performance anion exchange membrane water electrolysers. Nat. Energy 5, 378–385 (2020).

    Article  Google Scholar 

  2. Abbasi, R. et al. A roadmap to low-cost hydrogen with hydroxide exchange membrane electrolyzers. Adv. Mater. 31, e1805876 (2019).

    Article  Google Scholar 

  3. Schug, C. A. Operational characteristics of high-pressure, high-efficiency water-hydrogen-electrolysis. Int. J. Hydrogen Energy 23, 1113–1120 (1998).

    Article  Google Scholar 

  4. Lohmann-Richters, F. P., Renz, S., Lehnert, W., Müller, M. & Carmo, M. Review—challenges and opportunities for increased current density in alkaline electrolysis by increasing the operating temperature. J. Electrochem. Soc. 168, 114501 (2021).

    Article  Google Scholar 

  5. Lee, B., Lim, D., Lee, H. & Lim, H. Which water electrolysis technology is appropriate? Critical insights of potential water electrolysis for green ammonia production. Renew. Sustain. Energy Rev. 143, 110963 (2021).

    Article  Google Scholar 

  6. Hu, X. et al. Piperidinium functionalized aryl ether-free polyaromatics as anion exchange membrane for water electrolysers: performance and durability. J. Membr. Sci. 621, 118964 (2021).

    Article  Google Scholar 

  7. Jiao, K. et al. Designing the next generation of proton-exchange membrane fuel cells. Nature 595, 361–369 (2021).

    Article  Google Scholar 

  8. Olsson, J. S., Pham, T. H. & Jannasch, P. Poly(arylene piperidinium) hydroxide ion exchange membranes: synthesis, alkaline stability, and conductivity. Adv. Funct. Mater. 28, 1702758 (2018).

    Article  Google Scholar 

  9. Li, D. et al. Durability of anion exchange membrane water electolyzers. Energy Environ. Sci. 14, 3393 (2021).

    Article  Google Scholar 

  10. Holmes, T., Skalski, T. J. G., Adamski, M. & Holdcroft, S. Stability of hydrocarbon fuel cell membranes: reaction of hydroxyl radicals with sulfonated phenylated polyphenylenes. Chem. Mater. 31, 1441–1449 (2019).

    Article  Google Scholar 

  11. Tang, H. et al. Fuel cells with an operational range of −20 °C to 200 °C enabled by phosphoric acid-doped intrinsically ultramicroporous membranes. Nat. Energy 7, 153–162 (2022).

    Article  Google Scholar 

  12. Kraglund, M. R. et al. Ion-solvating membranes as a new approach towards high rate alkaline electrolyzers. Energy Environ. Sci. 12, 3313–3318 (2019).

    Article  Google Scholar 

  13. Aili, D. et al. Towards a stable ion-solvating polymer electrolyte for advanced alkaline water electrolysis. J. Mater. Chem. A 5, 5055–5066 (2017).

    Article  Google Scholar 

  14. Xing, B. & Savadogo, O. Hydrogen/oxygen polymer electrolyte membrane fuel cells (PEMFCs) based on alkaline-doped polybenzimidazole (PBI). Electrochem. Commun. 2, 697–702 (2000).

    Article  Google Scholar 

  15. Hu, B. et al. A stable ion-solvating PBI electrolyte enabled by sterically bulky naphthalene for alkaline water electrolysis. J. Membr. Sci. 643, 120042 (2022).

    Article  Google Scholar 

  16. Hu, X., Liu, M., Huang, Y., Liu, L. & Li, N. Sulfonate-functionalized polybenzimidazole as ion-solvating membrane toward high-performance alkaline water electrolysis. J. Membr. Sci. 663, 121005 (2022).

    Article  Google Scholar 

  17. Grigoriev, S. A., Fateev, V. N., Bessarabov, D. G. & Millet, P. Current status, research trends, and challenges in water electrolysis science and technology. Int. J. Hydrogen Energy 45, 26036–26058 (2020).

    Article  Google Scholar 

  18. Zhang, K. et al. Status and perspectives of key materials for PEM electrolyzer. Nano Res. Energy 1, e9120032 (2022).

    Article  Google Scholar 

  19. Hernandez, M. C. G. et al. Novel, metal-free, superacid-catalyzed ‘click’ reactions of isatins with linear, nonactivated, multiring aromatic hydrocarbons. Macromolecules 43, 6968–6979 (2010).

    Article  Google Scholar 

  20. Hossain, I., Husna, A., Jeong, I. & Kim, T.-H. Biphenyl(isatin-co-trifluoroacetophenone)-based copolymers synthesized using the Friedel–Crafts reaction as mechanically robust membranes for efficient CO2 separation. ACS Appl. Polym. Mater. 4, 3779–3790 (2022).

    Article  Google Scholar 

  21. Zhang, S., Zhu, X. & Jin, C. Development of a high-performance anion exchange membrane using poly(isatin biphenylene) with flexible heterocyclic quaternary ammonium cations for alkaline fuel cells. J. Mater. Chem. A 7, 6883–6893 (2019).

    Article  Google Scholar 

  22. Pulido, B., Chisca, S. & Nunes, S. P. Solvent and thermal resistant ultrafiltration membranes from alkyne-functionalized high-performance polymers. J. Membr. Sci. 564, 361–371 (2018).

    Article  Google Scholar 

  23. Lin, B. et al. Alkaline stable C2-substituted imidazolium-based anion-exchange membranes. Chem. Mater. 25, 1858–1867 (2013).

    Article  Google Scholar 

  24. Klumpp, D. A., Yeung, K. Y., Surya Prakash, G. K. & Olah, G. A. Preparation of 3,3-diaryloxindoles by superacid-induced condensations of isatins and aromatics with a combinatorial approach. J. Org. Chem. 63, 4 (1998).

    Article  Google Scholar 

  25. Cruz, A. R. et al. Precision synthesis of narrow polydispersity, ultrahigh molecular weight linear aromatic polymers by A2 + B2 nonstoichiometric step-selective polymerization. Macromolecules 45, 6774–6780 (2012).

    Article  Google Scholar 

  26. Bruce, J. M. & Sutcliffe, F. K. Heterocyclic compounds of nitrogen. Part I. The alkylation and acylation of 3-phenyloxindole, and the preparation of some derivatives of 2-hydroxy-3-phenylindole, J. Chem. Soc. 1957, 4789–4798 (1957).

  27. Bordwell, F. G. & Fried, H. E. Heterocyclic aromatic anions with 4n + 2 π-electrons. J. Org. Chem. 56, 4218–4224 (1991).

    Article  Google Scholar 

  28. Wang, J. W., Jiang, L., Huang, H. H., Han, Z. & Ouyang, G. Rapid electron transfer via dynamic coordinative interaction boosts quantum efficiency for photocatalytic CO2 reduction. Nat. Commun. 12, 4276 (2021).

    Article  Google Scholar 

  29. Zeng, L., Zhao, T. S., An, L., Zhao, G. & Yan, X. H. Physicochemical properties of alkaline doped polybenzimidazole membranes for anion exchange membrane fuel cells. J. Membr. Sci. 493, 340–348 (2015).

    Article  Google Scholar 

  30. Aili, D. et al. Understanding ternary poly(potassium benzimidazolide)-based polymer electrolytes. Polymer 84, 304–310 (2016).

    Article  Google Scholar 

  31. Chang, Z. et al. Chemical oxidative degradation of polybenzimidazole in simulated environment of fuel cells. Polym. Degrad. Stab. 94, 1206–1212 (2009).

    Article  Google Scholar 

  32. Wang, J. et al. Poly(aryl piperidinium) membranes and ionomers for hydroxide exchange membrane fuel cells. Nat. Energy 4, 392–398 (2019).

    Article  Google Scholar 

  33. Kraglund, M. R. et al. Zero-gap alkaline water electrolysis using ion-solvating polymer electrolyte membranes at reduced KOH concentrations. J. Electrochem. Soc. 163, F3125–F3131 (2016).

    Article  Google Scholar 

  34. Choe, Y.-K. et al. Alkaline stability of benzyl trimethyl ammonium functionalized polyaromatics: a computational and experimental study. Chem. Mater. 26, 5675–5682 (2014).

    Article  Google Scholar 

  35. Vengatesan, S., Santhi, S., Jeevanantham, S. & Sozhan, G. Quaternized poly (styrene-co-vinylbenzyl chloride) anion exchange membranes for alkaline water electrolysers. J. Power Sources 284, 361–368 (2015).

    Article  Google Scholar 

  36. Liu, Z. et al. The effect of membrane on an alkaline water electrolyzer. Int. J. Hydrogen Energy 42, 29661–29665 (2017).

    Article  Google Scholar 

  37. Chu, X., Shi, Y., Liu, L., Huang, Y. & Li, N. Piperidinium-functionalized anion exchange membranes and their application in alkaline fuel cells and water electrolysis. J. Mater. Chem. A 7, 7717–7727 (2019).

    Article  Google Scholar 

  38. Li, D. et al. Phenyl oxidation impacts the durability of alkaline membrane water electrolyzer. ACS Appl. Mater. Interfaces 11, 9696–9701 (2019).

    Article  Google Scholar 

  39. Li, H. et al. Poly(vinyl benzyl methylpyrrolidinium) hydroxide derived anion exchange membranes for water electrolysis. J. Mater. Chem. A 7, 17914–17922 (2019).

    Article  Google Scholar 

  40. Su, X. et al. Novel piperidinium functionalized anionic membrane for alkaline polymer electrolysis with excellent electrochemical properties. J. Membr. Sci. 581, 283–292 (2019).

    Article  Google Scholar 

  41. Cha, M. S. et al. Poly(carbazole)-based anion-conducting materials with high performance and durability for energy conversion devices. Energy Environ. Sci. 13, 3633–3645 (2020).

    Article  Google Scholar 

  42. Lee, H. I. et al. Advanced Zirfon-type porous separator for a high-rate alkaline electrolyser operating in a dynamic mode. J. Membr. Sci. 616, 118541 (2020).

    Article  Google Scholar 

  43. Park, H. J., Lee, S. Y., Lee, T. K., Kim, H.-J. & Lee, Y. M. N3-butyl imidazolium-based anion exchange membranes blended with poly(vinyl alcohol) for alkaline water electrolysis. J. Membr. Sci. 611, 118355 (2020).

    Article  Google Scholar 

  44. Park, Y. S. et al. Superior performance of anion exchange membrane water electrolyzer: ensemble of producing oxygen vacancies and controlling mass transfer resistance. Appl. Catal. B 278, 119276 (2020).

    Article  Google Scholar 

  45. Yan, X. et al. Twisted ether-free polymer based alkaline membrane for high-performance water electrolysis. J. Power Sources 480, 228805 (2020).

    Article  Google Scholar 

  46. Chen, N. et al. High-performance anion exchange membrane water electrolyzers with a current density of 7.68 A cm−2 and durability of 1000 h. Energy Environ. Sci. 14, 6338–6348 (2021).

    Article  Google Scholar 

  47. Xu, Z. et al. Anisotropic anion exchange membranes with extremely high water uptake for water electrolysis and fuel cell. J. Mater. Chem. A 9, 23485 (2021).

    Article  Google Scholar 

  48. Liu, M., Hu, X., Hu, B., Liu, L. & Li, N. Soluble poly(aryl piperidinium) with extended aromatic segments as anion exchange membranes for alkaline fuel cells and water electrolysis. J. Membr. Sci. 642, 119966 (2022).

    Article  Google Scholar 

  49. Diaz, L. A. et al. Alkali-doped polyvinyl alcohol – polybenzimidazole membranes for alkaline water electrolysis. J. Membr. Sci. 535, 45–55 (2017).

    Article  Google Scholar 

  50. Konovalova, A. et al. Blend membranes of polybenzimidazole and an anion exchange ionomer (FAA3) for alkaline water electrolysis: improved alkaline stability and conductivity. J. Membr. Sci. 564, 653–662 (2018).

    Article  Google Scholar 

Download references

Acknowledgements

We thank X. Zhang from Nanjing University of Science and Technology for the simulations and M. Dou at the Institute of Coal Chemistry of the Chinese Academy of Sciences for help with the NMR. We also thank Shiyanjia Lab (www.shiyanjia.com) for support during the DFT test. Financial support for this work was provided by the National Natural Science Foundation of China (Grant Nos. 21835005 and 22105217), the STS Project of the Chinese Academy of Sciences (Grant No. KFJ-STS-QYZD-2021-02-003) and the Natural Science Foundation of Shanxi Province (Grant No. 20210302124433).

Author information

Authors and Affiliations

  1. State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, China

    Xu Hu, Bin Hu, Chengyuan Niu, Min Liu, Yingda Huang, Shuanyan Kang, Kang Geng & Nanwen Li

  2. Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, China

    Xu Hu, Bin Hu, Min Liu & Nanwen Li

  3. Ningbo Sino-Tech Hydrogen Membrane Technology Co., Ltd, Ningbo, China

    Jin Yao

  4. State Key Laboratory for Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China

    Huabing Tao

Authors
  1. Xu Hu
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Bin Hu
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Chengyuan Niu
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Jin Yao
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Min Liu
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Huabing Tao
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Yingda Huang
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Shuanyan Kang
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. Kang Geng
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. Nanwen Li
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

N.L. initiated this collaborative project. K.G. helped with data collection and the formal analysis. X.H. synthesized the polymeric materials, designed the experiments and wrote the original draft of the manuscript. C.N. and J.Y. set up the testing system at high operating pressure and high temperature and collected the data. K.G., B.H., M.L., H.T. and S.K. characterized the electrolyser tests and reviewed the draft of the manuscript. Y.H., N.L. and K.G. contributed to the writing of the manuscript. K.G. and N.L. supervised and guided the work.

Corresponding authors

Correspondence to Kang Geng or Nanwen Li.

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature Energy thanks Patric Jannasch, Jens Oluf Jensen and Yu Seung Kim for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Figs. 1–3 show the alkaline stability of a small molecule. Supplementary Fig. 4 shows the dynamic thermomechanical analysis of POBP. Supplementary Figs. 5–14 show the swelling behaviour, XRD, structure and hydrophily of all the POBPs. Supplementary Figs. 15 and 16 show the thermal stability of POBP. Supplementary Figs. 17–19 show the alkaline and oxidative stability of POBP. Supplementary Figs. 20–28 show the AWE device performance of POBP. Supplementary Figs. 29–35 show the in situ stability of POBP under different conditionals. Supplementary Table 1 lists the solubility of the POBP and Supplementary Table 2 lists the polymerization conditions of the POBP.

Supplementary Data 1

Source Data for Supplementary Figs. 1–35.

Source data

Source Data for Fig. 1

DFT calculation and alkaline stability test of model compounds.

Source Data for Fig. 2

Preparation, composition, mechanical properties and gas permeability characterization of POBP-ISMs.

Source Data for Fig. 3

Ion conductivity, alkaline durability, oxidation stability of POBP and 1H NMR spectra of pristine and aged POBP after alkaline during test and Fenton test.

Source Data for Fig. 4

Polarization curves of POBP-ISM AWE under different conditions and area resistance (AR).

Source Data for Fig. 5

In situ durability of electrolyser with POBP-ISMs at 80 °C and comparison of in situ durability and cell voltage of present POBP-ISM and current ISMs and AEMs.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Hu, X., Hu, B., Niu, C. et al. An operationally broadened alkaline water electrolyser enabled by highly stable poly(oxindole biphenylene) ion-solvating membranes. Nat Energy 9, 401–410 (2024). https://doi.org/10.1038/s41560-023-01447-w

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41560-023-01447-w

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing