High-rate electrochemical energy storage through Li+ intercalation pseudocapacitance

Journal name:
Nature Materials
Year published:
Published online

Pseudocapacitance is commonly associated with surface or near-surface reversible redox reactions, as observed with RuO2·xH2O in an acidic electrolyte. However, we recently demonstrated that a pseudocapacitive mechanism occurs when lithium ions are inserted into mesoporous and nanocrystal films of orthorhombic Nb2O5 (T-Nb2O5; refs 1, 2). Here, we quantify the kinetics of charge storage in T-Nb2O5: currents that vary inversely with time, charge-storage capacity that is mostly independent of rate, and redox peaks that exhibit small voltage offsets even at high rates. We also define the structural characteristics necessary for this process, termed intercalation pseudocapacitance, which are a crystalline network that offers two-dimensional transport pathways and little structural change on intercalation. The principal benefit realized from intercalation pseudocapacitance is that high levels of charge storage are achieved within short periods of time because there are no limitations from solid-state diffusion. Thick electrodes (up to 40 μm thick) prepared with T-Nb2O5 offer the promise of exploiting intercalation pseudocapacitance to obtain high-rate charge-storage devices.

At a glance


  1. Kinetic analysis of the electrochemical behaviour of
    Figure 1: Kinetic analysis of the electrochemical behaviour of T-Nb2O5.

    a, Cyclic voltammograms from 100 to 500 mV s−1 demonstrate the high-rate capability of the material. bb-value determination of the peak anodic and cathodic currents shows that this value is approximately 1 up to 50 mV s−1. This indicates that even at the peak currents, charge storage is capacitive. c, Capacity versus v−1/2 allows for the separation of diffusion-controlled capacity from capacitive-controlled capacity; two distinct kinetic regions emerge when the sweep rate is varied from 1 to 500 mV s−1. The dashed diagonal line corresponds to the extrapolation of the infinite sweep rate capacitance using the capacity between 2 and 20 mV s−1. d, The variation of the cathodic peak voltage with the sweep rate exhibits a region of small peak separation followed by increased separation at 20 mV s−1, and represents another method of identifying systems with facile intercalation kinetics.

  2. Electrochemical cycling of a 40-μm-thick
T-Nb2O5 electrode.
    Figure 2: Electrochemical cycling of a 40-μm-thick T-Nb2O5 electrode.

    a, Galvanostatic cycling of a thick Nb2O5 electrode at a 10C rate. b, Comparison of the rate capability of T-Nb2O5 with a high-rate lithium-ion anode, Li4Ti5O12, at various C-rates (Li4Ti5O12 data reproduced from ref. 16).

  3. Structural features of lithium intercalation in
    Figure 3: Structural features of lithium intercalation in T-Nb2O5.

    a, The structure of T-Nb2O5 stacked along the c axis demonstrates the layered arrangement of oxygen (red) and niobium (inside polyhedra) atoms along the ab plane. b, Derivative of Nb K-edge X-ray absorption near-edge spectra at selected cell voltages, showing a systematic shift to lower energies as Nb5+ is reduced to Nb4+. ck2-weighted Fourier-transformed Nb K-edge EXAFS at selected cell voltages.


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Author information


  1. Department of Materials Science and Engineering, University of California, Los Angeles, California 90095, USA

    • Veronica Augustyn,
    • Jong Woung Kim &
    • Bruce Dunn
  2. Department of Materials Science, Université Paul Sabatier, CIRIMAT UMR CNRS 5085, Toulouse 31062, France

    • Jérémy Come,
    • Pierre-Louis Taberna &
    • Patrice Simon
  3. Réseau sur le Stockage Electrochimique de l’Energie (RS2E), FR CNRS 3459, France

    • Jérémy Come,
    • Pierre-Louis Taberna &
    • Patrice Simon
  4. Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA

    • Michael A. Lowe &
    • Héctor D. Abruña
  5. Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA

    • Sarah H. Tolbert


V.A., J.C., M.A.L. and J.W.K.: experimental work, data analysis. P-L.T., S.H.T., H.D.A., P.S., B.D.: project planning, data analysis.

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The authors declare no competing financial interests.

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