Preparation Of Two-dimensional Material TI3C2TX And Electrochemical Performance Of Lithium/sodium Ion Battery

Lithium-ion batteries have been widely applicated from common small electronic products to large-scale public transport,acting in concert with the use of various types of clean energy to reduce the consumption of primary energy rate and improve the quality of the environment.As one of the most important parts of battery structure,electrode material has become one of the hot topics in recent research.In 2011,an emerging two-dimensional layered structure material-MXene was born as an hotspot material of the lithium-ion battery anode research hotspot,due to its excellent conductivity and lower lithium-ion diffusion resistance.In this paper,Ti3C2Tx MXene materials was used as the research object to explore the preparation process and the preliminary prepared multilayer Ti3C2Tx was intercalaed and ultrasonic stripped.Moreover,TiO2/Ti3C2Tx composites was through in-situ synthesis to explore the degree of etching,stripping and composite TiO2 on the layer structure,the effect of the surface state of the material on the electrochemical properties.First of all,commercial Ti3AIC2 as raw material,method that high concentrations of hydrofluoric acid etching was used to explore particle size,different etching time and etching temperature on the structure of the material to determine the best synthesis process and successfully synthesize as-Ti3C2Tx.The structure,morphology and surface status of as-Ti3C2Tx were analyzed by means of XRD,SEM,TEM and XPS.The lithium ion batteries were assembled and the specific discharge capacity of 200mAh g-1 can be obtained at a current density of 20mA g-1.When the current density was increased to 1000mA g-1 and then reduced to 20mA g-1,the discharge specific capacity can still reach 150 mAh g-1,indicating that the material has great rate performance.Secondly,the multi-layer structure of as-Ti3C2Tx was changed into a two-dimensional structure with less layers by alcohol and dimethyl sulfoxide(DMSO)as intercalation agent and the method of ultrasonic liquid stripping and the laminar size of as-Ti3C2Tx also decreased.At the same time,it was found that the content of functional groups on the surface of the sample decreased after the intercalation and delamination.The first discharge capacities of d-a-Ti3C2Tx and d-D-Ti3C2Tx were 484.9mAh g-1 and 443.1 mAh g-1 at 20mA g-1,respectively,so their rate performance was good and the capacity significantly improved comparing with as-Ti3C2Tx.Moreover,as the negative electrode of sodium ion battery both have a capacity of 110 mAh g-1 and 90 mAh g-1 with excellent cycling stability at the 100 mA g-1 current density after 500 cycles.In the end,using as-Ti3C2Tx as raw material,Ti3C2Tx/TiO2 composite material was prepared by means of directly hydrothermal method and dding a certain amount of water and glucose to build a rich pore structure between layers.Applicated in lithium-ion batteries,the reversible specific capacity of TiO2-Ti3C2Tx and TiO2@C-Ti3C2Tx was about 210mAh g-1 and about 230mAh g-1 at a current density of 20mAg-1,respectively.In the sodium ion batteries,after 400 cycles,both of which could still provide the specific capacity of 102mAh g-1 and 99mAh g-1 at 100mAg-1.The coulombic efficiency remained above 98%,and the cycling stability was outstanding.