Study On Modification Of High Nickel Layered Cathode Material LiNi_0.6Co_0.2Mn_0.2O₂

The acceleration of modernization also accelerates the consumption of resources and intensifies the pollution to the environment,the task of developing new green energy is imminent.Compared with other traditional battery,lithium-ion battery has the advantages of higher specific capacity,better cycle stability,safety and environmental protection.Among them,Ni in high nickel ternary cathode material Li Ni_0.6Co_0.2Mn_0.2O₂ further improves its energy density,therefore,it has been widely studied by scientific researchers.However,the instability of Ni this material also leads to low material cycle retention and poor rate performance.In order to make up for the defects of the material itself,the initial NCM622 was synthesized by sol-gel method,and then La³⁺doped,La₄Ni Li O₈ coated NCM622and Na⁺doped Ce O₂ coated NCM622 were synthesized by the same process.The results show that the modified material has better electrochemical properties and more stable structure.The details are as follows:（1）The original NCM622 and La³⁺doped,La₄Ni Li O₈ modified NCM622samples were synthesized with acetate of Li,Ni,Co,Mn and La as solute,citric acid as chelating agent and deionized water as solvent.The test results show that the part of La³⁺introduced system enters the lattice to improve the structural stability of the material,and the rest forms La₄Ni Li O₈ with Li and Ni,which is coated on the surface of NCM22,improves the surface structure of the material and enhances its interface stability.When 2 at%La³⁺was added,the capacity retention rate of the sample was 96.54%after 100 cycles in the 2.7 V～4.3 V at 1C rate,which was much higher than 74.12%of the initial sample;The specific capacity of 2 at%La sample in the first cycle of discharge at 5C high current rate is 117.54 m Ah/g,which is also slightly higher than 108.10 m Ah/g of unmodified sample.（2）Na⁺doped and Ce O₂ coated NCM622 samples were synthesized with acetate of Li,Ni,Co,Mn,Na and Ce as solute,citric acid as chelating agent and deionized water as solvent.Similar to the first experiment,the first coulomb efficiency,first discharge specific capacity,capacity retention rate of 100 cycles at1C and discharge capacity at 5C of the modified samples were 91.16%,215.4m Ah/g,93.05%and 127.53 m Ah/g respectively,which were much higher than the initial samples.Na⁺doping and Ce O₂ coating comprehensively improve the electrochemical properties of the materials.