Preparation And Electrochemical Properties Of Single Crystal LiNi_0.83Co_0.12Mn_0.05O₂ Cathode Material

Nowadays,the active cathode material that is focused on in the lithium battery cathode material market is mainly high nickel ternary cathode material.This active material has the advantages of more suitable production cost and higher capacity,but also has low electronic conductivity,cycle rate performance and Disadvantages such as poor high temperature performance.Therefore,this article first uses the co-precipitation-hydrothermal method to prepare the single-crystal material precursor Ni_0.83Co_0.12Mn_0.05（OH）₂,which is prepared by designing a reasonable sintering process,matching the appropriate lithium ratio,and high-temperature sintering.Single crystal LiNi_0.83Co_0.12Mn_0.05O₂cathode material,the influence of relevant sintering process parameters on the morphology,structure and electrochemical performance of single crystal material was explored.In addition,this paper also uses two methods of doping with F element and carbon coating with polymer PVP as the organic carbon source to modify the single crystal material,which effectively improves the physical and chemical properties of the single crystal material.The main research conclusions are as follows:（1）The experiment found that the single crystal LiNi_0.83Co_0.12Mn_0.05O₂ternary active material synthesized under the conditions of pure oxygen atmosphere,860℃,holding time for 16 h,and lithium content of 1.09 has a relatively stable layered crystal structure and a relatively good particle dispersion.Uniformity,smooth crystal grain surface,low cation mixing,and the single crystal material prepared under this optimal condition also has good physical and chemical properties,the first discharge specific capacity is as high as 200.86m Ah/g,and it is cycled under a rate cycle of 0.2 C After 100 times,the capacity retention rate is as high as 96.46%.（2）The experiment adopts the method of low-temperature sintering to modify the single crystal morphology cathode material obtained under the optimal preparation conditions by doping with F element,which effectively improves the structural stability and crystallization performance of the single crystal material,and enables the growth of crystals.More complete.Experimental data shows that when the molar amount of F doping reaches 1%,the prepared LiNi_0.83Co_0.12Mn_0.05O_1.99F_0.01composite material has the best cycle performance and rate performance,and the first discharge specific capacity is 199.2 m Ah/g.After 100 cycles under0.2 C rate cycle,the capacity retention rate is 99.51%.In addition,the material has a higher capacity retention rate than the discharge specific capacity of 0.1 C under the charge and discharge rate conditions of 0.2 C,0.5 C,1 C,2 C,and 5 C.（3）The experiment also uses polymer PVP as the organic carbon source to coat the surface carbon of the single crystal cathode material prepared under the optimal conditions.The experimental results show that the single crystal material coated with carbon effectively reduces the loss of active material of the single crystal material during the cycle,and also reduces the side reaction between the single crystal material and the electrolyte.In addition,through related electrochemical tests,it is found that when the mass ratio of PVP reaches1.5%,the single crystal LiNi_0.83Co_0.12Mn_0.05O₂/C composite has better rate performance and cycle performance.Under the condition of 0.2 C charge and discharge rate The first discharge specific capacity is 195.2 m Ah/g,and the capacity retention rate is 98.47%after 100 cycles.In addition,the material has a higher capacity retention rate than the discharge specific capacity of 0.1 C under the charge and discharge rate conditions of 0.2 C,0.5 C,1 C,2 C,and5 C.