Two-dimensional composite of Nitrogen-doped graphitic Carbon-coated cobaltosic oxide nanocrystals on MXene nanosheets as High-performance anode for Lithium-ion batteries

Abstract MXenes are a new family of 2D materials that have attracted significant attention as promising substrates for the design of advanced anode materials for Li-ion batteries (LIBs). This is attributed to the high conductivity and low Li-ion diffusion barrier of MXenes. In this study, we developed a facile technique for the synthesis of 2D-structured composites comprising N-doped graphitic C (NGC)-coated Co3O4 and MXene nanosheets (denoted as Co3O4@NGC/MX). The Co-based metal–organic frameworks (ZIF-67) formed on the MXene nanosheets were converted into Co3O4@NGC via reduction under inert conditions and subsequent oxidation. The presence of MXene nanosheets in the composite resulted in high electronic conductivity and structural robustness. The Co3O4 nanoparticles functioned as effective Li-ion reservoirs and inhibited the restacking of MXene nanosheets, while the NGC prevented the deterioration of Co3O4 nanoparticles and were active for Li storage. The Co3O4@NGC/MX composite was utilized as an electrode material for LIBs, and it delivered an excellent electrochemical performance. The electrode exhibited a high cycling stability with a capacity of 830 mA h g−1 after 500 cycles at 1.0 A g−1 and an outstanding rate capability with a capacity of 327 mA h g−1 at 50.0 A g−1.