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.