High-Performance Layered CaV₄O₉-MXene Composite Cathodes for Aqueous Zinc Ion Batteries

Due to their reliability, affordability and high safety, rechargeable aqueous zinc ion batteries (ZIBs) have garnered a lot of attention. Nevertheless, undesirable long-term cycle performance and the inadequate energy density of cathode materials impede the development of ZIBs. Herein, we report a layered CaV₄O₉-MXene (Ti₃C₂T) composite assembled using CaV₄O₉ nanosheets on Ti₃C₂T_x and investigate its electrochemical performance as a new cathode for ZIBs, where CaV₄O₉ nanosheets attached on the surface of MXene and interlamination create a layered 2D structure, efficiently improving the electrical conductivity of CaV₄O₉ and avoiding the stacking of MXene nanosheets. The structure also enables fast ion and electron transport. Further discussion is conducted on the effects of adding MXene in various amounts on the morphology and electrochemical properties. The composite shows an improved reversible capacity of 274.3 mA h g^-1 at 0.1 A g^-1, superior rate capabilities at 7 A g^-1, and a high specific capacity of 107.6 mA h g^-1 can be delivered after 2000 cycles at a current density of 1 A g^-1. The improvement of the electrochemical performance is due to its unique layered structure, high electrical conductivity, and pseudo capacitance behavior.