Orbital‐Modulated Cu‐Doped VO ₂ Nanoflowers via Glucose‐Assisted Synthesis: Structural Optimization and Electronic Coupling Engineering for High‐Capacity Aqueous Aluminum Ion Batteries

Vanadium oxide cathode materials in aqueous aluminum-ion batteries (AAIBs) have an exceptional potential for development because of their high valence and fast electron transfer capability. However, the strong electron-electron Coulomb repulsion in vanadium and its associated electrostatic interactions severely hinder the feasibility of vanadium oxides in AAIBs. The glucose-assisted hydrothermal reduction of monoclinic VO₂ combined with Cu ion doping effectively promotes the self-assembly of VO₂ into nanoflower architectures, enabling precise control over morphology and crystalline structure. When integrated with a 5 m Al(OTF)₃ electrolyte and an Ionic liquid （IL ）-treated Al sheet anode, this full battery demonstrates outstanding electrochemical performance, achieving an initial discharge capacity of 642 mAh·g^-1 at 0.4 A·g^-1. Moreover, introducing Cu_3d orbitals effectively enhances the hybridization and electronic coupling effects between the V_3d and O_2p orbitals. Ex situ characterization and diffusion kinetic provide insights into the embedding/de-embedding mechanism of Al³⁺. This work significantly improves the application potential of VO₂ in AAIBs through structural optimization and mechanism studies and provides systematic scientific guidance for the development of vanadium oxide cathode materials.