Phase-Transition Intervention Engineered Amorphous Vanadium Oxide for High-Performance Aqueous Zinc-Ion Batteries

Amorphous vanadium oxide (AVO) has emerged as a promising cathode material for aqueous zinc-ion batteries (AZIBs), combining the high theoretical capacity and low cost of crystalline vanadium oxides with improved kinetics and structural tolerance. However, AVO still faces critical challenges, including thermodynamic instability, poor electrical conductivity, and severe dissolution in aqueous electrolytes, which limit its practical application. Herein, we propose a novel "phase-transition intervention" strategy for the synthesis of AVO. In this approach, polyaniline molecules are first intercalated into layered V₂O₅·1.6H₂O, followed by high-temperature treatment. During the thermally induced phase transition of V₂O₅·1.6H₂O, the intercalated polyaniline molecules undergo in situ carbonization and form nitrogen-doped carbon layers, which simultaneously disrupt long-range crystallinity and promote the formation of AVO confined in nitrogen-doped carbon layers. The carbon layers provide the AVO with suppressed dissolution, enhanced electrical conductivity, and improved thermodynamic stability. The resulting composite exhibits excellent AZIB performance, delivering high capacities of 390.5 and 329.9 mAh g^-1 at 0.1 and 20.0 A g^-1, respectively, and outstanding cycling stability. This work offers a versatile strategy for designing amorphous electrode materials and opens new directions for high-energy aqueous zinc-ion batteries.