Letter | Published:

Conductive two-dimensional titanium carbide ‘clay’ with high volumetric capacitance

Nature volume 516, pages 7881 (04 December 2014) | Download Citation

Abstract

Safe and powerful energy storage devices are becoming increasingly important. Charging times of seconds to minutes, with power densities exceeding those of batteries, can in principle be provided by electrochemical capacitors—in particular, pseudocapacitors1,2. Recent research has focused mainly on improving the gravimetric performance of the electrodes of such systems, but for portable electronics and vehicles volume is at a premium3. The best volumetric capacitances of carbon-based electrodes are around 300 farads per cubic centimetre4,5; hydrated ruthenium oxide can reach capacitances of 1,000 to 1,500 farads per cubic centimetre with great cyclability, but only in thin films6. Recently, electrodes made of two-dimensional titanium carbide (Ti3C2, a member of the ‘MXene’ family), produced by etching aluminium from titanium aluminium carbide (Ti3AlC2, a ‘MAX’ phase) in concentrated hydrofluoric acid, have been shown to have volumetric capacitances of over 300 farads per cubic centimetre7,8. Here we report a method of producing this material using a solution of lithium fluoride and hydrochloric acid. The resulting hydrophilic material swells in volume when hydrated, and can be shaped like clay and dried into a highly conductive solid or rolled into films tens of micrometres thick. Additive-free films of this titanium carbide ‘clay’ have volumetric capacitances of up to 900 farads per cubic centimetre, with excellent cyclability and rate performances. This capacitance is almost twice that of our previous report8, and our synthetic method also offers a much faster route to film production as well as the avoidance of handling hazardous concentrated hydrofluoric acid.

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References

  1. 1.

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

  2. 2.

    et al. High-rate electrochemical energy storage through Li+ intercalation pseudocapacitance. Nature Mater. 12, 518–522 (2013)

  3. 3.

    & True performance metrics in electrochemical energy storage. Science 334, 917–918 (2011)

  4. 4.

    et al. Volumetric capacitance of compressed activated microwave-expanded graphite oxide (a-MEGO) electrodes. Nano Energy 2, 764–768 (2013)

  5. 5.

    , , , & Liquid-mediated dense integration of graphene materials for compact capacitive energy storage. Science 341, 534–537 (2013)

  6. 6.

    , & Hydrous ruthenium oxide as an electrode material for electrochemical capacitors. J. Electrochem. Soc. 142, 2699–2703 (1995)

  7. 7.

    et al. Two-dimensional nanocrystals produced by exfoliation of Ti3AlC2. Adv. Mater. 23, 4248–4253 (2011)

  8. 8.

    et al. Cation intercalation and high volumetric capacitance of two-dimensional titanium carbide. Science 341, 1502–1505 (2013)

  9. 9.

    , , , & Liquid exfoliation of layered materials. Science 340, 6139 (2013)

  10. 10.

    et al. High-volumetric performance aligned nano-porous microwave exfoliated graphite oxide-based electrochemical capacitors. Adv. Mater. 25, 4879–4885 (2013)

  11. 11.

    et al. Towards ultrahigh volumetric capacitance: graphene derived highly dense but porous carbons for supercapacitors. Sci. Rep. 3, 2975 (2013)

  12. 12.

    , , & Tunable electrical conductivity of individual graphene oxide sheets reduced at “low” temperatures. Nano Lett. 8, 4283–4287 (2008)

  13. 13.

    MAX Phases: Properties of Machinable Ternary Carbides and Nitrides (John Wiley & Sons, 2013)

  14. 14.

    , , & MXenes: a new family of two-dimensional materials. Adv. Mater. 26, 982 (2014)

  15. 15.

    et al. Surface Al leached Ti3AlC2 substituting carbon for catalyst support served in a harsh corrosive electrochemical system. Nanoscale 6, 11035–11040 (2014)

  16. 16.

    et al. Unique lead adsorption behavior of activated hydroxyl group in two-dimensional titanium carbide. J. Am. Chem. Soc. 136, 4113–4116 (2014)

  17. 17.

    , & Are MXenes promising anode materials for Li ion batteries? computational studies on electronic properties and Li storage capability of Ti3C2 and Ti3C2X2 (X = F, OH) monolayer. J. Am. Chem. Soc. 134, 16909–16916 (2012)

  18. 18.

    et al. Intercalation and delamination of layered carbides and carbonitrides. Nature Commun. 4, 1716 (2013)

  19. 19.

    et al. Transparent conductive two-dimensional titanium carbide epitaxial thin films. Chem. Mater. 26, 2374–2381 (2014)

  20. 20.

    , , , & Synthesis of a new graphene-like transition metal carbide by de-intercalating Ti3AlC2. Mater. Lett. 109, 295–298 (2013)

  21. 21.

    & Two-dimensional titanium carbonitrides and their hydroxylated derivatives: structural, electronic properties and stability of MXenes Ti3C2−xNx(OH)2 from DFTB calculations. J. Solid State Chem. 207, 42–48 (2013)

  22. 22.

    & The swelling behaviour of clays. Appl. Clay Sci. 4, 143–156 (1989)

  23. 23.

    & Why clays swell. J. Phys. Chem. B 106, 12664–12667 (2002)

  24. 24.

    , , , & Liquid flow along a solid surface reversibly alters interfacial chemistry. Science 344, 1138–1142 (2014)

  25. 25.

    , , , & Kinetics of aluminum extraction from Ti3AlC2 in hydrofluoric acid. Mater. Chem. Phys. 139, 147–152 (2013)

  26. 26.

    Electrochemical capacitors based on pseudocapacitance. In Electrochemical Supercapacitors: Scientific Fundamentals and Technological Applications (Kluwer Academic/Plenum, 1999)

  27. 27.

    , , , & Local atomic structure and conduction mechanism of nanocrystalline hydrous RuO2 from X-ray scattering. J. Phys. Chem. B 106, 12677–12683 (2002)

  28. 28.

    , , & Pseudocapacitive contributions to electrochemical energy storage in TiO2 (anatase) nanoparticles. J. Phys. Chem. C 111, 14925–14931 (2007)

  29. 29.

    et al. Solving the capacitive paradox of 2D MXene by electrochemical quartz-crystal admittance and in situ electronic conductance measurements. Adv. Energy Mater. (2014)

  30. 30.

    , & Where do batteries end and supercapacitors begin? Science 343, 1210–1211 (2014)

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Acknowledgements

We thank O. Mashtalir and Z. Ling for help with material characterization. This work was supported by the US National Science Foundation under grant number DMR-1310245. Electrochemical research was supported by the Fluid Interface Reactions, Structures and Transport (FIRST) Center, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, and Office of Basic Energy Sciences. XRD, X-ray photoelectron spectroscopy, SEM and TEM investigations were performed at the Centralized Research Facilities at Drexel University.

Author information

Author notes

    • Michael Ghidiu
    •  & Maria R. Lukatskaya

    These authors contributed equally to this work.

Affiliations

  1. Department of Materials Science and Engineering, and A. J. Drexel Nanomaterials Institute, Drexel University, Philadelphia, Pennsylvania 19104, USA

    • Michael Ghidiu
    • , Maria R. Lukatskaya
    • , Meng-Qiang Zhao
    • , Yury Gogotsi
    •  & Michel W. Barsoum

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Contributions

M.G. conducted material synthesis and XRD analysis. M.R.L. performed electrochemical measurements and SEM analysis. M.-Q.Z. performed TEM analysis. M.W.B. and Y.G. planned and supervised the research. M.R.L., M.G., M.W.B. and Y.G. wrote the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Yury Gogotsi or Michel W. Barsoum.

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https://doi.org/10.1038/nature13970

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