In Situ Electrochemical Transformation toward Structure Optimized VEG@MXene Cathode for Enhanced Zinc-Ion Storage

Abstract

Vanadium-based derivatives, featuring affordable cost and high theoretical capacity, have gathered widespread interest in the context of aqueous zinc-ion batteries (ZIBs). However, the further application of vanadium-based materials is hindered by the limited electrical conductivity and cycling lifespan. Herein, 1D chain-like structure vanadyl ethylene glycolate (VEG, (VO(CH2O)2)), growing on the Ti3C2Tx MXene nanosheets, is synthesized via a one-step oil-bath heating process as cathode materials for ZIBs. Benefiting from the hybrid structure with high conductivity and abundant reactive sites, the VEG@MXene cathode exhibits a remarkable specific capacity (360.3 mAh g−1 at 0.5 A g−1), and impressive capacity retention (up to 85.2% after 3000 cycles at 10 A g−1). Mechanism analysis reveals a gradual phase transition from the original VEG on MXene to the stable Zn3V2O7(OH)2·2H2O nanoflakes accompanied by continuous zinc ion intercalation/deintercalation, offering more pathways for zinc ion transport. This work suggests that engineering conductivity-enhanced vanadium-based materials is a rational approach for developing promising cathode materials of ZIBs.