Synthesis And Electrochemical Properties Of MOFs And Its Derivatives/V₂CT_x Composites

MOFs and their derivatives are considered to be a promising class of anode materials for lithium-ion batteries because of their high theoretical specific capacity.However,their low electrical conductivity and cyclic volume expansion hinder their practical application.In this paper,MOFs and their derivatives/V₂CT_xcomposites were prepared by combining MOFs materials and their derivatives with V₂CT_x through in-situ growth,taking advantage of the high electrical conductivity and good electrochemical cycling stability of the new two-dimensional material V₂CT_x MXene.And the prepared materials were applied to lithium-ion battery anode materials,the main research results are as follows.（1）In situ growth of Co-MOF materials on V₂CT_x MXene by a simple hydrothermal method to obtain Co-MOF/V₂CT_x composites.The influence of different proportions of Co-MOF on the structure and electrochemical properties of Co-MOF/V₂CT_x composites were also systematically studied.The Co-MOF in composite materials provided additional specific capacity,so that Co-MOF/V₂CT_x electrode material maintained a high specific capacity.Furthermore,thanks to the strong bonding between MXene and Co-MOF,the Co-MOF material had better structural stability in the composite,which allowed the Co-MOF/V₂CT_xcomposite exhibited excellent cycling stability during charging and discharging.The Co-MOF/V₂CT_x electrode material exhibited a high specific capacity of 483.4 m Ah g^-1 after 120 cycles at 100m Ag^-1 and exhibited good cycling stability even after 300 cycles at a high current density of 500 m A g^-1.The unique synergistic design of this work could provide new ideas for the development of MXene based composites in energy storage applications.（2）We made Co₃O₄@NGC/V₂CT_xcomposites by growing ZIF-67 material on the V₂CT_x surface,then carbonizing and oxidizing them at high temperatures.The influence of different proportions of Co₃O₄ on the structure and electrochemical properties of Co₃O₄@NGC/V₂CT_x composites were also systematically studied.When the Co₃O₄@NGC/V₂CT_x composite was used as an anode material for Li-ion batteries,the electrode material exhibited a high specific capacity of 700.9 m Ah g^-1after 180cycles at 100 m Ag^-1.Furthermore,the electrode material exhibited specific capacity of420.3 m Ah g^-1after 600 cycles at 500 m Ag^-1,and the average coulomb efficiency of the electrode material is consistently above 98%during the cycle.This is due to the fact that the Co₃O₄ in the composite relieved the re-stacking of MXene and expanded the active site of Li⁺,while MXene improved the electrical conductivity of the composite and accelerated the transport of Li⁺.This study shows that the synergistic effect of MOFs derivatives and MXene can effectively improve the electrochemical performance of lithium-ion battery anodes.