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On the molecular origin of supercapacitance in nanoporous carbon electrodes

Abstract

Lightweight, low-cost supercapacitors with the capability of rapidly storing a large amount of electrical energy can contribute to meeting continuous energy demands and effectively levelling the cyclic nature of renewable energy sources1. The excellent electrochemical performance of supercapacitors is due to a reversible ion adsorption in porous carbon electrodes. Recently, it was demonstrated that ions from the electrolyte could enter sub nanometre pores, greatly increasing the capacitance2,3,4. However, the molecular mechanism of this enhancement remains poorly understood. Here we provide the first quantitative picture of the structure of an ionic liquid adsorbed inside realistically modelled microporous carbon electrodes. We show how the separation of the positive and negative ions occurs inside the porous disordered carbons, yielding much higher capacitance values (125 F g−1) than with simpler electrode geometries5. The proposed mechanism opens the door for the design of materials with improved energy storage capabilities. It also sheds new light on situations where ion adsorption in porous structures or membranes plays a role.

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Figure 1: The EDLC simulation cell.
Figure 2: Typical structure of the ionic liquid inside electrified pores of the CDC-1200 material.
Figure 3: Density profiles normal to the electrode surface for graphite and CDC materials.
Figure 4: Influence of the material local structure on the charging of the carbon atoms.

References

  1. 1

    Miller, J. R. & Simon, P. Electrochemical capacitors for energy management. Science 321, 651–652 (2008).

    CAS  Article  Google Scholar 

  2. 2

    Chmiola, J. et al. Anomalous increase in carbon capacitance at pore sizes less than 1 nm. Science 313, 1760–1763 (2006).

    CAS  Article  Google Scholar 

  3. 3

    Raymundo-Piñero, E., Kierzek, K., Machnikowski, J. & Béguin, F. Relationship between the nanoporous texture of activated carbons and their capacitance properties in different electrolytes. Carbon 44, 2498–2507 (2006).

    Article  Google Scholar 

  4. 4

    Largeot, C. et al. Relation between the ion size and pore size for an electric double-layer capacitor. J. Am. Chem. Soc. 130, 2730–2731 (2008).

    CAS  Article  Google Scholar 

  5. 5

    Merlet, C., Salanne, M., Rotenberg, B. & Madden, P. A. Imidazolium ionic liquid interfaces with vapor and graphite: Interfacial tension and capacitance from coarse-grained molecular simulations. J. Phys. Chem. C 115, 16613–16618 (2011).

    CAS  Article  Google Scholar 

  6. 6

    Simon, P. & Gogotsi, Y. Materials for electrochemical capacitors. Nature Mater. 7, 845–854 (2008).

    CAS  Article  Google Scholar 

  7. 7

    Huang, J., Sumpter, B. G. & Meunier, V. Theoretical model for nanoporous carbon supercapacitors. Angew. Chem. Int. Ed. 47, 520–524 (2008).

    CAS  Article  Google Scholar 

  8. 8

    Yang, L., Fishbine, B. H., Migliori, A. & Pratt, L. R. Molecular simulation of electric double-layer capacitors based on carbon nanotube forests. J. Am. Chem. Soc. 131, 12373–12376 (2009).

    CAS  Article  Google Scholar 

  9. 9

    Shim, Y. & Kim, H. J. Nanoporous carbon supercapacitors in an ionic liquid: A computer simulation study. ACS Nano 4, 2345–2355 (2010).

    CAS  Article  Google Scholar 

  10. 10

    Feng, G. A. et al. The importance of ion size and electrode curvature on electrical double layers in ionic liquids. Phys. Chem. Chem. Phys. 13, 1152–1161 (2011).

    CAS  Article  Google Scholar 

  11. 11

    Kornyshev, A. A. Double-layer in ionic liquids: Paradigm change? J. Phys. Chem. B 111, 5545–5557 (2007).

    CAS  Article  Google Scholar 

  12. 12

    Armand, M., Endres, F., MacFarlane, D. R., Ohno, H. & Scrosati, B. Ionic-liquid materials for the electrochemical challenges of the future. Nature Mater. 8, 621–629 (2009).

    CAS  Article  Google Scholar 

  13. 13

    Lanning, O. & Madden, P. Screening at a charged surface by a molten salt. J. Phys. Chem. B 108, 11069–11072 (2004).

    CAS  Article  Google Scholar 

  14. 14

    Fedorov, M. V. & Kornyshev, A. A. Ionic liquid near a charged wall: Structure and capacitance of electrical double layer. J. Phys. Chem. B 112, 11868–11872 (2008).

    CAS  Article  Google Scholar 

  15. 15

    Vatamanu, J., Borodin, O. & Smith, G. D. Molecular insights into the potential and temperature dependences of the differential capacitance of a room-temperature ionic liquid at graphite electrodes. J. Am. Chem. Soc. 132, 14825–14833 (2010).

    CAS  Article  Google Scholar 

  16. 16

    Fedorov, M. V. & Kornyshev, A. A. Towards understanding the structure and capacitance of electrical double layer in ionic liquids. Electrochim. Acta 53, 6835–6840 (2008).

    CAS  Article  Google Scholar 

  17. 17

    Feng, G., Huang, J., Sumpter, B. G., Meunier, V. & Qiao, R. A ‘counter-charge layer in generalized solvents’ framework for electrical double layers in neat and hybrid ionic liquid electrolytes. Phys. Chem. Chem. Phys. 13, 14723–14734 (2011).

    CAS  Article  Google Scholar 

  18. 18

    Bazant, M. Z., Storey, B. D. & Kornyshev, A. A. Double layer in ionic liquids: Overscreening versus crowding. Phys. Rev. Lett. 106, 046102 (2011).

    Article  Google Scholar 

  19. 19

    Kondrat, S. & Kornyshev, A. A. Superionic state in double-layer capacitors with nanoporous electrodes. J. Phys. Condens. Matter 23, 022201 (2011).

    CAS  Article  Google Scholar 

  20. 20

    Kondrat, S., Georgi, N., Fedorov, M. V. & Kornyshev, A. A. A superionic state in nanoporous double-layer capacitors: Insights from Monte Carlo simulations. Phys. Chem. Chem. Phys. 13, 11359–11366 (2011).

    CAS  Article  Google Scholar 

  21. 21

    Palmer, J. C. et al. Modeling the structural evolution of carbide-derived carbons using quenched molecular dynamics. Carbon 48, 1116–1123 (2010).

    CAS  Article  Google Scholar 

  22. 22

    Reed, S. K., Lanning, O. J. & Madden, P. A. Electrochemical interface between an ionic liquid and a model metallic electrode. J. Chem. Phys. 126, 084704 (2007).

    Article  Google Scholar 

  23. 23

    Pounds, M., Tazi, S., Salanne, M. & Madden, P. A. Ion adsorption at a metallic electrode: An ab initio based simulation study. J. Phys. Condens. Matter 21, 424109 (2009).

    CAS  Article  Google Scholar 

  24. 24

    Chmiola, J., Largeot, C., Taberna, P-L., Simon, P. & Gogotsi, Y. Desolvation of ions in subnanometer pores and its effect on capacitance and double-layer theory. Angew. Chem. Int. Ed. 47, 3392–3395 (2008).

    CAS  Article  Google Scholar 

  25. 25

    Hardacre, C., Holbrey, J. D., Nieuwenhuyzen, M. & Youngs, T. G. A. Structure and solvation in ionic liquids. Acc. Chem. Res. 40, 1146–1155 (2007).

    CAS  Article  Google Scholar 

  26. 26

    Ohkubo, T. et al. Restricted hydration structures of Rb and Br ions confined in slit-shaped carbon nanospace. J. Am. Chem. Soc. 124, 11860–11861 (2002).

    CAS  Article  Google Scholar 

  27. 27

    Willard, A. P. & Chandler, D. Instantaneous liquid interfaces. J. Phys. Chem. B 114, 1954–1958 (2010).

    CAS  Article  Google Scholar 

  28. 28

    Roy, D. & Maroncelli, M. An improved four-site ionic liquid model. J. Phys. Chem. B 114, 12629–12631 (2010).

    CAS  Article  Google Scholar 

  29. 29

    Vora, P. M. et al. Correlating magnetotransport and diamagnetism of sp2–bonded carbon networks through the metal–insulator transition. Phys. Rev. B 84, 155114 (2011).

    Article  Google Scholar 

Download references

Acknowledgements

We acknowledge the support of the French Agence Nationale de la Recherche (ANR) under Grant ANR-2010-BLAN-0933-02 (‘Modelling the Ion Adsorption in Carbon Micropores’). We are grateful for the computing resources on Hector (UK National HPC) provided by EPSRC through the UKCP consortium. Y.G. is supported by the US National Science Foundation under International Collaborations in Chemistry Grant No. 0924570. P.S. and Y.G. thank the Partner University Fund (PUF) for funding their collaborative efforts. We thank J. C. Palmer and K. Gubbins for providing us the raw data from ref. 21.

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C.M., B.R., P.A.M. and M.S. designed the research. C.M. carried out simulations. All authors contributed to the analysis and discussion of the data and writing the manuscript.

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Correspondence to Mathieu Salanne.

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The authors declare no competing financial interests.

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Merlet, C., Rotenberg, B., Madden, P. et al. On the molecular origin of supercapacitance in nanoporous carbon electrodes. Nature Mater 11, 306–310 (2012). https://doi.org/10.1038/nmat3260

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