Researchers in Singapore report the first use of TiNb2O7 as an insertion-type anode in a lithium-ion hybrid electrochemical capacitor (Li-HEC) along with an activated carbon (AC) counter electrode derived from a coconut shell. The Li-HEC delivers very high energy and power densities of approximately 43 Wh kg-1 and 3 kW kg-1, respectively.
Furthermore, the AC/TiNb2O7 Li-HEC delivers a good cyclability of 3 000 cycles with about 84 % of the initial value. A paper on their work is published in the journal ChemSusChem.
A simple and scalable electrospinning technique is adopted to prepare one-dimensional TiNb2O7 nanofibers that can be characterized by XRD with Rietveld refinement, SEM, and TEM. The lithium insertion properties of such electrospun TiNb2O7 are evaluated in the half-cell configuration (Li/TiNb2O7) and it is found that the reversible intercalation of lithium (≈3.45 mol) is feasible with good capacity retention characteristics. The Li-HEC is constructed with an optimized mass loading based on the electrochemical performance of both the TiNb2O7 anode and AC counter electrode in nonaqueous media.—Aravindan et al.
Aravindan, V., Sundaramurthy, J., Jain, A., Kumar, P. S., Ling, W. C., Ramakrishna, S., Srinivasan, M. P. and Madhavi, S. (2014) “Unveiling TiNb2O7 as an Insertion Anode for Lithium Ion Capacitors with High Energy and Power Density,” ChemSusChem doi: 10.1002/cssc.201400157