Carbon-coated Li₃V₂(PO₄)₃ as insertion type electrode for lithium-ion hybrid electrochemical capacitors: An evaluation of anode and cathodic performance

We first report the possible utilization of carbon-coated Li₃V₂(PO₄)₃ (LVP-C) phase as insertion type anode and cathode in Lithium-ion hybrid electrochemical capacitor (Li-HEC) applications with activated carbon (AC) counter electrode. Conventional sol-gel technique is utilized to prepare LVP-C and characterized by various techniques like powder X-ray diffraction, field emission scanning electron microscopy and high resolution transmission electron microscopy. Li-cycling studies are performed in half-cell assembly to evaluate the optimum mass loading for the fabrication of Li-HEC. A reversible capacity of ∼125 and ∼91 mAh g^-1 is noted (current density of 100 mA g^-1) when LVP-C is employed as cathode (3-4.3 V vs. Li) and anode (1-3 V vs. Li), respectively. Li-HEC is constructed in an organic electrolyte and tested in two configurations, using LVP-C as positive electrode and AC as the negative electrode (LVP-C/AC) and the second one composed of AC as the positive electrode and LVP-C as the negative electrode (AC/LVP-C). The LVP-C/AC and AC/LVP-C Li-HECs delivered maximum energy densities of ∼27 and ∼25 Wh kg^-1, respectively.