Preparation And Modification Of LiNi_0.8Co_0.1Mn_0.1O₂ Cathode Material For Lithium Battery

With the gradual reduction of traditional fossil energy,traditional energy sources are gradually depleted and environmental pollution is becoming more and more serious.Lithium-ion batteries have attracted more and more attention as clean and efficient new energy sources.Now ternary cathode material is the hotspot of cathode materials for lithium ion batteries,because it has the advantages of three materials:LiNiO₂,LiCoO₂ and LiMnO₂.High-nickel material LiNi_0.8Co_0.1Mn_0.1O₂?NCM811?has the advantages of high theoretical specific capacity and low cost and so on.However,due to the increase of nickel content,the phenomenon of cation disordering becomes even more serious.This will affect the cycle performance and rate performance of materials to varying degrees.We hope to solve these problems by exploring new synthetic methods and modify the material.Here we synthesized NCM811 precursor by nano ball milling and spray drying,then LiNi_0.8Co_0.1Mn_0.1O₂ cathode material is prepared by high-temperature calcination under oxygen atmosphere.Then explore the effect of process conditions such as milling time,rotating speed,particle size of precursor materials,and calcining temperature on the physical and electrochemical properties of the material.The result is:when the rotation speed is 2500 r/min and the milling time is 120 min,the obtained precursor material has the smallest particle size of 246 nm.Two-stage calcination at500°C and 800°C yields the best crystallinity of NCM811 material.SEM analysis shows that the material is a secondary particle formed by the agglomeration of primary particles.The primary particle diameter is about 200³00 nm.The initial discharge capacity of the sample obtained under optimal conditions was 166.4 mAh/g.After 50 cycles at 1 C rate,the capacity retention rate of the material reached 93.4%.The Rb-doped Rb_x Li_?1-x?Ni_0.8Co_0.1Mn_0.1O₂?x=0,0.005,0.01,0.02?cathode material was prepared by the same method according to the best process.We studied the influence of ion doping on the phase structure and electrochemical properties of the material and explored the optimal Rb doping amount.When x=0.005,that is sample Rb0.5%,The first discharge specific capacity at 0.5C is 188.9 mAh/g,which is 13.52%higher than that of sample Rb0%.After 100 cycles,the capacity retention rate of material Rb 0.5%is 88.9%,which is 14.08%higher than Rb0%.After the EIS calculation,the diffusion coefficient of Li⁺ions is1.14×10^-10 cm²·s^-1,it is 3.42 times that of the sample without Rb.