Preparation And Study On Electrochemical Properties Of 3D Ti₃C₂T_x

With the development of science and technology,energy storage devices have gradually entered people's lives and played an increasingly important role.The development of energy storage devices with excellent performance has become the focus.Electrode plays an important role in various components of energy storage device.Since 2011,a new two-dimensional material family-MXenes,has emerged in the world of two-dimensional materials.Its excellent performance in the field of energy storage and other fields has aroused great interest of researchers.The titanium powder,the aluminum powder and the graphite powder are uniformly mixed by an atomic ratio of 3:1.1:1.8 by solid phase sintering,and then solid phase sintered at a temperature of1650°C for 2 hours to obtain a MAX phase material;followed by the liquid etching of MAX phase,etched sample?MXene?shows that the material is highly pure and has no other miscellaneous items.Then the MXene material was characterized.Firstly,the FTIR and Raman tests showed that the surface of Ti₃C₂T_x material had-OH,=O,-F functional groups,and then the transmission electron microscopy was carried out,and results showed that the material was micron-sized two-dimensional.Next,three materials were prepared by using the Ti₃C₂T_x single layer material,namely a Ti₃C₂T_x flexible film material prepared by using a lithium battery separator,a vacuum dried 3D Ti₃C₂T_x material at-196°C,and a vacuum dried 3D Ti₃C₂T_x material at-30°C.The scanning electron microscopy?SEM?shows that the Ti₃C₂T_x flexible film is a two-dimensional structure in which monolithic layers are stacked on each other,and the vacuum-dried 3D Ti₃C₂T_x material after freezing is a three-dimensional structure with micron-sized pores.And vacuum-dried 3D Ti₃C₂T_x material after freezing at-30°C has larger pores and no wrinkles in the material.Previous electrochemical studies have shown that electrode materials with excellent structural often have excellent electrochemical properties.For further verification,we have prepared three MXene material electrodes for use in lithium-ion batteries.It can be seen that the 3D Ti₃C₂T_x material is more suitable as an electrode of lithium-ion batteries than the traditional flexible membrane material.At a current density of 50 mA/g,the conventional flexible membrane has a capacity of only about10 mAh/g as the electrode of the lithium ion battery.The vacuum-dried 3D Ti₃C₂T_x electrode after freezing at-196°C has a capacity of 339.9 mAh/g after 1500 cycles at a current density of 50 mAh/g,while the 3D Ti₃C₂T_x material after freezing at-30°C has a capacity of 390.8 mAh/g after 1500 cycles at a current density of 50 mAh/g.At the rate performance test,the 3D Ti₃C₂T_x material has a much higher capacity at the same current density than the conventional flexible membrane material,and has a capacity of239.7 mAh/g at a current density of 1 A/g.And through CV test,it can be concluded that the energy storage principle of 3D Ti₃C₂T_x and Ti₃C₂T_x flexible film have not changed,and they are pseudocapacitive.It can be concluded from the AC impedance spectroscopy that the 3D Ti₃C₂T_x material has a small interfacial resistance and a large ion diffusion coefficient,and has better electrochemical kinetics and diffusion properties than conventional flexible film materials.In order to further verify the electrochemical properties of 3D Ti₃C₂T_x,we applied 3D Ti₃C₂T_x to the capacitor system.First in lithium-ion capacitor system testing materials,electrochemical experiments showed that vacuum-dried 3D Ti₃C₂T_x electrode after freezing at-30°C electrochemical performance is best,and preparation of quality capacity can reach 130.6 F/g under the scanning speed of 2 mV/s,specific energy and specific power can reach 222.2 Wh/kg and 9996.2 W/kg,far higher than the traditional flexible membrane.Then 3D Ti₃C₂T_x were applied to sodium and magnesium ion capacitors,and electrochemical tests showed that they had good electrochemical effects in both systems.At the sweep rate of 2 mV/s,the mass capacity of sodium ion capacitor can reach 110.1 F/g,and that of magnesium ion capacitor can reach 71.6 F/g.This paper focuses on the preparation of 3D Ti₃C₂T_x by template method and proves its advantages in electrochemical properties through electrochemical comparison.Subsequently,it is applied in the electrochemical properties research of sodium ion and magnesium ion capacitor,providing a good reference for the preparation and electrochemical research of other 3D MXenes materials.