Zn3V2O7(OH)2·2H2O/MXene cathode with fast ion diffusion for highly durable zinc ion batteries.

V-based materials are considered promising candidates as cathode materials for zinc ion batteries (ZIBs). However, the inherent low conductivity of V-based compounds leads to the sluggish diffusion kinetics of Zn2+ and serious cycling capacity degradation of ZIBs. Herein, 1D Zn3V2O7(OH)2·2H2O (ZVO) nanowires were grown on monodisperse 2D Ti3C2T x MXene nanosheets via a facile microwave-assisted method. The introduction of Ti3C2T x MXenes effectively improved the conductivity and hydrophilicity of ZVO. Furthermore, the Zn2+ diffusion coefficient of ZVO/Ti3C2T x composites was enhanced to 10-7-10-8 cm2 s-1, which was superior to that of pure ZVO nanowires (10-8-10-10 cm2 s-1) and other previously reported typical V-based cathodes. The ZIBs based on the ZVO/Ti3C2T x cathode possessed an excellent discharge specific capacity of 215.2 mAh g-1 at 0.1 A g-1 and cycling stability (84% retention over 14 000 cycles at 10 A g-1). Moreover, the flexible Zn//ZVO/Ti3C2T x ZIBs using a gel electrolyte still exhibited good cycling stability and rate performance.