Dual Strategies of Metal Preintercalation and In Situ Electrochemical Oxidization Operating on MXene for Enhancement of Ion/Electron Transfer and Zinc-Ion Storage Capacity in Aqueous Zinc-Ion Batteries.

As an emerging two-dimensional material, MXenes exhibit enormous potentials in the fields of energy storage and conversion, due to their superior conductivity, effective surface chemistry, accordion-like layered structure, and numerous ordered nanochannels. However, interlayer accumulation and chemical sluggishness of structural elements have hampered the demonstration of the superiorities of MXenes. By metal preintercalation and in situ electrochemical oxidization strategies on V 2 CT x , MXene has enlarged its interplanar spacing and excited the outermost vanadium atoms to achieve frequent transfer and high storage capacity of Zn ions in aqueous zinc-ion batteries (ZIBs). Benefiting from the synergistic effects of these strategies, the resulting VO x /Mn-V 2 C electrode exhibits the high capacity of 530 mA h g -1 at 0.1 A g -1 , together with a remarkable energy density of 415 W h kg -1 and a power density of 5500 W kg -1 . Impressively, the electrode delivers excellent cycling stability with Coulombic efficiency of nearly 100% in 2000 cycles at 5 A g -1 . The satisfactory electrochemical performances bear comparison with those in reported vanadium-based and MXene-based aqueous ZIBs. This work provides a new methodology for safe preparation of outstanding vanadium-based electrodes and extends the applications of MXenes in the energy storage field.