LiVPO₄F: A New Cathode for High-Energy Lithium Ion Capacitors

We report, for the first time, the possibility of using tavorite type LiVPO₄F as insertion electrode for Li-ion capacitor configuration with carbonaceous counterpart i. e. activated carbon (AC) in organic medium. Carbothermal reduction process is successfully employed to prepare LiVPO₄F and the as-prepared material is subsequently characterized using various analytical techniques. Single electrode studies are conducted to estimate the optimum mass loading between two electrodes. A reversible capacity of 120 mAh g^–1 is obtained when cycled between 3–4.5 V vs. Li at current density of 50 mA g^–1. This has been further studied as cathode in a Li-ion capacitor configuration with AC. The LiVPO₄F/AC configuration delivered the maximum energy density of 30 Wh kg^–1. A good cycleability is also evidenced, for instance, ∼90 % of the initial value is retained after 1000 cycles.