Preparation And Research Of Electrochemical Performance Based On Ti₃C₂T_x Nanomaterials

MXenes is a rapidly rising two-dimensional material in today’s material science era.Among them,Ti₃C₂T_x,the most widely studied MXenes material,is one of the most suitable electrode materials for preparing supercapacitors due to its excellent volume capacitance,metal-like conductivity,adjustable surface functional groups,and two-dimensional structure advantages.However,as with other two-dimensional materials,Ti₃C₂T_x inevitably suffers from the problem of stacking and agglomeration of nanosheets,which will reduce the overall active surface sites and hinder the transport of electrolyte ions,affecting its actual capacity performance.Given the above problems,Ti₃C₂T_x was compounded with transition metal oxides and sulfides to improve the electrochemical performance of the material by designing the structure of the composite material,and its structural morphology and capacity,cyclic stability,and other electrochemical properties were studied and analyzed.The main conclusions are as follows:（1）Zn Co₂O₄/Ti₃C₂T_x composite electrode material was obtained by growing Zn Co₂O₄ porous nanosheets on few-layer Ti₃C₂T_x nanosheets by a method of co-precipitation combined with calcination.The test results show that the Zn Co₂O₄/Ti₃C₂T_x composite calcined at 350℃exhibits the best electrochemical performance among the prepared electrode materials(1 A g^-1 can reach a specific capacity of 195.8 C g^-1).In addition,the assembled hybrid supercapacitor Zn Co₂O₄/Ti₃C₂T_x|AC（Activated Carbon）can achieve an energy density of 15.6 Wh kg^-1 with good cycling stability.The improved performance of the Zn Co₂O₄/Ti₃C₂T_xcomposite electrode material can be attributed to the fact that the vertically aligned Zn Co₂O₄ porous nanosheets can provide abundant active sites and effectively inhibit the self-stacking of Ti₃C₂T_x nanosheets,buffer the volume change during the electrochemical process,and make the Zn Co₂O₄ nanosheets have better stability;at the same time,Ti₃C₂T_x nanosheets can accelerate the transfer of electrons in the electrochemical reaction and shorten the channel of electrolyte ion diffusion as a two-dimensional conductive matrix.（2）Ni S₂/Ti₃C₂T_x composites were prepared by an oil bath combined with a high-temperature in situ sulfuration process.The structure and morphology of the Ni S₂/Ti₃C₂T_x composites were characterized by XRD,XPS,TEM,and other tests.The results show that there is a strong interaction between Ni S₂ and Ti₃C₂T_x,and the Ni S₂nanosheets are uniformly anchored in the exfoliated few-layer Ti₃C₂T_x sheet.The energy density of the prepared hybrid supercapacitor Ni S₂/Ti₃C₂T_x can reach 34.53 Wh kg^-1,which is much higher than that of Ni S₂|AC(26.14 Wh kg^-1),and the capacity retention was 85.21%after long-term cycle test.The Ni S₂/Ti₃C₂T_x composite material can take advantage of the synergistic advantages of the large theoretical capacity and thermodynamic stability of Ni S₂ nanosheets and the high conductivity of Ti₃C₂T_x,thereby preparing supercapacitor electrode materials with excellent performance.（3）Ni Co₂S₄/Ti₃C₂T_x composites with uniform growth of Ni Co₂S₄ nanoparticles on the surface of Ti₃C₂T_x were synthesized by the co-precipitation method combined with a solvothermal strategy.After forming a hybrid capacitor with an AC electrode,Ni Co₂S₄/Ti₃C₂T_x|AC can reach an energy density of 35.52 Wh kg^-1,which is much higher than that of Ni Co₂S₄|AC(20.29 Wh kg^-1)and has good cycling stability.The use of Ti₃C₂T_x as a flexible conductive matrix can effectively inhibit the self-assembly effect of Ni Co₂S₄ particles and improve the electrical conductivity and electrochemical stability of the composite material;at the same time,Ni Co₂S₄ particles can also effectively inhibit the self-stacking defects of Ti₃C₂T_x nanosheets and improve the capacity of the composite material.