Research On Preparation And Electrochemical Performance Of Ti₃c₂t_x-based Nanocomposites

Because of its unique advantages,such as high power density,energy density,no memory effect,high safety and long cycle life,lithium-ion batteries have become the research hotspot in the field of batteries.Among them,the electrode material is the core materials and technology of lithium-ion battery,which will directly affect the battery capacity,charging speed and other properties.Therefore,the development of new high-performance electrode materials is very necessary and urgent.In this paper,two-dimensional carbide MXene was prepared by etching Ti₃AlC₂ with a mixed solution of lithium fluoride and hydrochloric acid.MXene was used as a matrix to prepare MXene nanocomposites and the performance as negative electrode of lithium-ion battery were studied.First,MoS₂/Ti₃C₂Tx nanocomposites were prepared by high-temperature solid-state sintering using Ti₃C₂T_x and ammonium thiomolybdate as a precursor.The morphology and structural were characterization by a series of methods.The electrochemistry performance was tested and the influence of MoS₂ on the electrochemical performance of nanocomposites as electrodes for Li-ion batteries was also analyzed.As a result,the MoS₂ nanoparticle on the MXene sheet increases the active site during charging and discharging cycles,which improves the electron conversion efficiency of the nanocomposite.In all cycles,MoS₂/Ti₃C₂T_x-10 has higher time capacity than pure Ti₃C₂T_x and MoS₂ electrodes and exhibit excellent reversible capacity,cycle stability and rate performance.Secondly,MXene and two-dimensional layered graphene oxide?GO?were used to prepare MXene/RGO nanocomposites by liquid-phase mixing and high temperature sintering method.The nanocomposites have good dispersibility and thin lamella structure The results of structural characterization and electrochemical tests show that the RGO in the nanocomposites effectively increases the contact area between the electrode material and the electrolyte,which may decrease the resistance of the material,increase the charge transfer efficiency and promote the rapid charge transfer.The RGO/Ti₃C₂T_x nanocomposite exhibited a stable capacity of 140 mAh/g;and maintained a relatively high coulombic efficiency in 200 cycles at a current density of1000 mA/g and exhibited better electrochemical performance than pure Ti₃C₂T_x electrode.Finally,a new Li₄Ti₅O₁₂/Ti₃C₂T_x nanocomposite was successfully prepared by high-temperature solid-state sintering method using Ti₃C₂T_x and lithium hydroxide as precursor.Through a series of structural characterization and electrochemical properties shown,the structure of Li₄Ti₅O₁₂/Ti₃C₂T_x nanocomposites increases their electrical conductivity as an electrode for lithium-ion batteries.The 0D/2D composite structure can increase the contact area between the nanocomposite electrode and the electrolyte;then,Ti₃C₂T_x nano-layer can reduce the resistance,and conductive to nanocomposite electron transfer.Compared with the pured Ti₃C₂T_x and LiTiO₂electrode,The Li₄Ti₅O₁₂/Ti₃C₂T_x electrode material has a reversible capacity of 236mAh/g at a current density of 50 mA/g,a higher specific capacity at current densities of 500 mA/g and 4000 mA/g.The Li₄Ti₅O₁₂/Ti₃C₂T_x electrode was cycled 200 times at a current density of 500 mA/g,resulting in a reversible capacity of 125 mAh/g.The results of electrochemical studies shown that the Li₄Ti₅O₁₂/Ti₃C₂T_x electrode has remarkable rate capability and cycling performance.