From crystalline to amorphous: V2CT MXene cathodes enable high-capacity and long-life aqueous zinc ion batteries

Vanadium-based compounds are promising cathodes for aqueous zinc ion batteries owing to their high capacity derived from multi-electron redox reactions. However, their practical application is often hampered by poor rate capability, caused by low electrical conductivity and sluggish Zn 2+ diffusion kinetics. Herein, we propose a precise amorphization strategy applied to conductive V 2 CT x MXene to overcome these limitations. Starting from exfoliated few-layer V 2 CT x , a controlled annealing process in argon induces a crystalline-to-amorphous transition, which effectively elevates the valence state of surface vanadium, creates abundant active sites for Zn 2+ storage, and expands the interlayer spacing to facilitate ion diffusion. Meanwhile, the intrinsic conductive V-C-V framework remains intact, ensuring rapid electron transport. As a result, the amorphous a-V 2 CT x cathode delivers remarkable electrochemical performance: a high reversible capacity of 543 mAh/g at 1 A/g, exceptional rate capability (494 mAh/g at 30 A/g), and outstanding cycling stability over 3000 cycles with a minimal decay rate of 0.012% per cycle. This work demonstrates the great potential of phase engineering MXenes for developing high-performance energy storage materials. Amorphization engineering of V 2 CT x MXene enables superior aqueous Zn-ion storage by synergistically enhancing ion diffusion kinetics and redox active sites. • Controlled amorphization boosts V valence and Zn²⁺ storage, enabling high capacity. • The conductive V–C–V network ensures fast electron/ion transport and high rate capability. • The a-V₂CTₓ cathode breaks the capacity–rate–stability trade-off in AZIBs.