Vanadium (III) Oxide/Carbon Core/Shell Hybrids as an Anode for Lithium-Ion Batteries

Abstract We present a facile two-step synthesis of vanadium (III) oxide/carbon core/shell hybrid material for application as lithium-ion battery electrode. The first step is a thermal treatment of a mixture of vanadium carbide (VC) and NiCl2 ⋅ 6H2O at 700 °C in an inert gas atmosphere. Elemental nickel obtained from decomposing NiCl2 ⋅ 6H2O served as a catalyst to trigger the local formation of graphitic carbon. In a second step, residual nickel was removed by washing the material in aqueous HCl. By replacing NiCl2 ⋅ 6H2O with anhydrous NiCl2, we obtained a hybrid material of vanadium carbide-derived carbon and a vanadium carbide core. Material characterization revealed a needle-like morphology of the rhombohedral V2O3 along with two carbon species with a different degree of graphitic ordering. We varied the NiCl2 ⋅ 6H2O-to-VC ratio, and the optimized material yielded a capacity of 110 mAh ⋅ g−1 at 2.5 A ⋅ g−1 which increased to 225 mAh ⋅ g−1 at 0.1 A ⋅ g−1 after 500 cycles in the potential range of 0.01-3.00 V vs. Li/Li+. This enhanced performance is in stark contrast to the loss of lithium uptake capacity when using commercially available V2O3 mixed with carbon black, where 93 % of the initial capacity was lost after 50 cycles.