Morphology Control, Surface Coating And Electrochemical Performance Of NaLiTi₃O₇ Anode Materials

The lithium ion anode material NaLiTi₃O₇ has been widely studied by researchers due to its lower voltage platform?¹.25 V?and higher theoretical capacity(281.6 mAh g^-1).In order to improve the electrochemical properties of materials,this paper studies the relationship between the structure and electrochemical properties of materials through morphology control and surface modification.First,the NaLiTi₃O₇ anode material was prepared by solid phase method,sol-gel method and solvothermal method.The results show that the materials synthesized by solid phase method and sol-gel method have almost no morphology and agglomeration is serious.The solvothermal synthesis material is porous microspheres,and the diameter of the microspheres is 0.8-1?m,and the solvothermal calcination temperature Lower,with better crystallinity and higher electrochemical performance.Because the morphology of the above three methods is difficult to control,and the electrochemical properties of the bulk materials obtained by the three methods are not ideal,in order to further improve the electrochemical properties of the materials,we control the structure of NaLiTi₃O₇ materials.Surface modification is performed to further improve electrochemical performance.Firstly,TiO₂ nanoparticles were prepared by solvothermal method,and NaLiTi₃O₇ nanoparticles were synthesized by solid phase method.Then,the surface of NaLiTi₃O₇ coated with different MgF₂ content was prepared by simple chemical deposition method.The results show that the synthesized material has a particle size of 150-250 nm,and the 5wt.%MgF₂ coated NaLiTi₃O₇ material has the best rate performance and cycle performance.In order to simplify the preparation process of the material,the paper further uses solvothermal method to adjust the morphology and in-situ coating of the material.HRTEM results confirmed that Er₂O₃ was successfully coated on NaLiTi₃O₇ nanorods with a cladding thickness of 2.5 nm.The EIS test results showed that the three samples of ErO-2,ErO-4 and ErO-6 exhibited much lower charge transfer resistance than ErO-0.Therefore,the Er₂O₃ coating improves the electrochemical activity of the anode material.