Enhancing the performance of aqueous zinc ion battery cathodes with a floral spherical V5O12·6H2O/V6O13/CNT nanocomposite

Abstract

Aqueous zinc ion batteries (AZIBs) offer a promising approach for electrical energy storage, combining cost-effectiveness and enhanced thermal safety. However, the cathode material, vanadium oxide, while known for its excellent theoretical specific capacity, faces a challenge in terms of its poor electronic conductance. In this study, we present a novel strategy to address this limitation by constructing the V₅O₁₂·6H₂O/V₆O₁₃/CNT (VOH/CNT) nanocomposite, resulting in significantly improved electrochemical performance. This nanocomposite was synthesized through a facile solvothermal method, yielding a unique floral spherical structure featuring a central cluster and multiple smaller groupings. The integration of CNTs into the composite significantly enhanced its electronic conductance, effectively mitigating the electronic conductance issue associated with vanadium oxide. Moreover, the composite retains crystalline water within its structure, playing a crucial role in providing a favorable ion-conductive pathway. Consequently, the VOH/CNT nanocomposite exhibits an impressive reversible capacity of 201 mA h g⁻¹ at 50 mA g⁻¹, surpassing that of VOH (116 mA h g⁻¹). Remarkably, even at a high current density, the VOH/CNT nanocomposite demonstrates an exceptional capacity retention, maintaining a capacity of 150 mA h g⁻¹ over 500 cycles at 1 A g⁻¹. Its outstanding electrochemical performance can be attributed to its distinctive structural arrangement, the conductive network facilitated by CNTs, and the introduced crystalline water component.