A Hyperstable Aqueous Zinc-Ion Battery Based on Mo_1.74CT_z MXene

The sustainable utilization of natural resources and growing demand for various electronic devices have promoted the development of safe, stable, and rechargeable aqueous zinc-ion batteries (AZIBs). However, a stable cathode material is crucial for ZIBs in an aqueous electrolyte, since it is more difficult for divalent Zn²⁺ to be reversibly inserted and extracted between active materials than it is for monovalent metal ions. In this work, a tailored multi-defect MXene, Mo_1.74CT_z, of a complete chemical formula of Mo_1.74±0.06CO_0.95±0.02(OH)_0.63±0.01F_0.3±0.03.0.2±0.05H₂O_ads (Mo_1.74CT_z), is assembled as cathode in AZIBs. It achieved 75% capacity retention and nearly 100% Coulombic efficiency even after up to 100 000 cycles as the intrinsic structural stability and many vertical holes of the Mo_1.74CT_z MXene contributed to alleviating the MXene collapse under repeated charge and discharge. Meanwhile, the Mo_1.74CT_z-based AZIBs exhibited good performance with a specific capacity of 200 mAh g^-1 at a current density of 0.2 A g^-1, which greatly exceeds previous reports of pure MXene-based cathodes in AZIBs. This work will aid in finding new solutions for sustainable energy development, which will pave the way for AZIBs as an alternative to lithium-ion batteries (LIBs) in the future.