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

• Published in: Batteries & supercaps 2019-01, Vol.2 (1), p.74-82
• Main Authors: Budak, Öznil, Srimuk, Pattarachai, Tolosa, Aura, Fleischmann, Simon, Lee, Juhan, Hieke, Stefan W., Frank, Anna, Scheu, Christina, Presser, Volker
• Format: Article
• Language: English
• Subjects: anode materials; carbide-derived carbon; hybrid materials; lithium-ion batteries; vanadia
• ISSN: 2566-6223; 2566-6223
• DOI: 10.1002/batt.201800115

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. Vanadium carbide and NiCl2 ⋅ 6H2O react at 700 °C in an inert gas atmosphere by the formation of a V2O3/C core/shell hybrid material. Elemental nickel is a side‐product that improves the degree of ordering of carbon and can be removed easily by HCl washing. When tested as electrode for lithium‐ion batteries, the best resulting hybrid material yielded a capacity of 225 mAh g−1 at 0.1 A ⋅ g−1 after 500 charge/discharge cycles in the potential range of 0.01‐3.00 V vs. Li/Li+.