Architecting Amorphous Vanadium Oxide/MXene Nanohybrid via Tunable Anodic Oxidation for High-Performance Sodium-Ion Batteries

Structural engineering and creating atomic disorder in electrodes are promising strategies for highly efficient and rapid charge storage in advanced batteries. Herein, a nanohybrid architecture is presented with amorphous vanadium oxide conformally coated on layered V2C MXene (a-VOx/V2C) via tunable anodic oxidation, which exhibits a high reversible capacity of 307 mAh g(-1) at 50 mA g(-1), decent rate capability with capacity up to 96 mAh g(-1) at 2000 mA g(-1), and good cycling stability as a cathode for sodium-ion batteries. The a-VOx layer enables reversible and fast Na+ insertion/extraction by providing sufficient vacancies and open pathways in the amorphous framework, unlike the irreversible phase transition in its crystalline counterpart, while layered V2C MXene offers abundant electron/ion transfer channels, which are joined together to boost the electrochemical performance. Notably the improved reversibility and structural superiority of the a-VOx/V2C nanohybrid are clearly revealed by in situ Raman, in situ transmission electron microscopy, in situ synchrotron X-ray absorption spectroscopy, and density functional theory calculations, demonstrating a reversible V-O vibration and valence oscillation between V4+ and V5+ in the disordered framework, with robust structural stability and unobstructed Na+ diffusion. This work provides a meaningful reference for the elaborate design of MXene-based nanostructured electrodes toward advanced rechargeable batteries.

Automated summary

The study presents a nanohybrid architecture of amorphous vanadium oxide conformally coated on layered V2C MXene, demonstrating high reversible capacity, decent rate capability, and good cycling stability for sodium-ion batteries. The nanohybrid enables reversible and fast Na+ insertion/extraction, while providing abundant electron/ion transfer channels to boost electrochemical performance. The structural superiority and improved reversibility of the nanohybrid are clearly revealed by various in situ techniques, showcasing its potential for advanced rechargeable batteries.