A nanoengineered vanadium oxide composite as a high-performance anode for aqueous Li-ion hybrid batteries†

Abstract

Aqueous lithium-ion batteries (LIBs) have received increasing attention as a promising solution for stationary energy storage systems due to their low environmental impact, non-flammability and low cost. Despite recent progress in electrolyte development and cathode manufacturing, the lack of anode materials with high specific capacity presents difficult challenges for a wide range of applications. In this study, we propose a novel synthetic strategy to fabricate a pseudocapacitive V₂O₅/graphene composite as a highly functional anode material for aqueous LIBs. The designed synthesis combines a fast laser-scribing step with controlled calcination to tune the morphology and oxidation state of the electrochemically active vanadium oxide species while obtaining a highly conductive graphene scaffold. The optimized V₂O₅/graphene anode shows an outstanding specific capacity of 158 mA h g⁻¹ in three-electrode measurements. When the V₂O₅/graphene anode is paired with an LiMn₂O₄ cathode, the charge storage mechanism of the full cell is revealed to be dominantly surface-controlled, resulting in remarkable rate performance. Specifically, the full cell can reach a specific capacity of 151 and 107 mA h (g anode)⁻¹ at C/6 and 3C, respectively. Moreover, this hybrid battery can achieve a high power density and an energy density of 650 W kg⁻¹ at 15.6 W h kg⁻¹ and 81.5 W h kg⁻¹ at 13.6 W kg⁻¹, respectively, outperforming most aqueous LIBs reported in the literature. This innovative strategy provides a pathway to incorporate pseudocapacitive electrodes for improving aqueous lithium-ion storage systems, enabling safe operation of large-scale energy storage without compromising their electrochemical performance.