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

Highlights: • A 2D structured composite consisting of Co₃O₄@NGC and MXene is facilely synthesized. • The N-doped graphitic carbon and MXene can enhance the robustness of the electrode material. • The composite demonstrates improved Li-ion storage performance. • Co₃O₄@NGC/MX delivered a capacity of 801 mA h g⁻¹ at 1.0 A g⁻¹ after 200 cycles. • It also has a capacity of 327 mA h g⁻¹ at a high current density of 50.0 A g^−1. 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.