Construction of waffle-like NS-ZIF@V2CTx heterostructures for high-performance potassium ion batteries

Abstract

V2CTx MXenes have attracted much attention in metal-ion battery due to their flexible interlayer spacing and high electronic conductivity. Unfortunately, lamellar V2CTx suffers from self-stacking phenomenon during charging and discharging process. Herein, the alternately stacked waffle-like NS-ZIF@V2CTx heterostructures with plentiful exposed active sites, enhanced electrical conductivity and superior structural stability have been fabricated and utilized as anode in potassium-ion battery. The ultrathin porous ZIF nanosheets for the waffle-like NS-ZIF@V2CTx heterostructures were tranformed from the ZIF nanoparticles through a innovative solvothermal reaction. It displays a large specific discharge capacity of 278 mA h g-1 over 200-lap cycling test at 100 mA g-1 while the electrode still maintains 100 mA h g-1 after 2000 cycles at a current density of 500 mA h g-1. The dense nano-network could not only increase the interlayer spacing of V2CTx MXene but also impede the occurrence of self stacking phenomenon of V2CTx, thus accelerating the diffusion and transport efficiency of electrons and ions. The waffle-like lightweight structures can increase the energy density of potassium-ion batteries. Ex-situ characterization and electrochemical kinetics test have been performed to vetify the superiority of waffle-like nanostructure. This study provides a inspired structure design strategy for developing MXene and MOF hybrid composites in the field of metal-ion battery research.