Preparation And Modification Of Nickel-rich LiNi_0.8Co_0.1Mn_0.1O₂ Electrode Material

Compared with the in-depth study of other cathode materials for lithium batteries,the nickel rich LiNi_0.8Co_0.1Mn_0.1O₂?NCM 811?sample was widely used in tramcar because of its superior energy density and cheaper cost.However,in practical application,NCM 811 material had the disadvantages of poor cycle performance and low first coulomb efficiency due to its internal Ni2+/Li+ mixed and external easy additional reaction with the electrolyte.To solve its shortcomings,NCM 811 materials were prepared by ball milling spray drying and solvothermal method respectively.The effects of different process parameters,different ratios Ti ions doped and Ti O2 coated on the NCM 811 cathode materials were investigated.The main research contents were as follows:?1?The NCM 811 cathode material was prepared by ball milling-spray drying method.The effects of different technological parameters such as solid content of solution,milling speed and time on the phase,particle size and electrochemical performance of the material were investigated.The results presented that when the solid content of the fixed solution was 35%,the milling speed was 2000 r min-1,and the milling time was 60 min,the synthesized material was of layered crystal structure and the particle size was uniform.The specific capacity retention rate of material was 78.80% after 150 cycles at 1 C.?2?Li1.05-xNi0.8Co0.1Mn0.1Tix O2?x=0,0.005,0.01?material was prepared by the same method with the best technological parameters.The influences of different amount of Ti ion doping on the structure,morphology and electrochemical property of NCM 811 material were investigated.The results shown that the Ni2+ content of Li1.045Ni0.8Co0.1Mn0.1Ti0.005O2 in the lithium layer decreased from 4.4%?pure sample?to 2.5%,and the specific capacity retention of material was 18% higher than that of NCM electrode material after 150 cycles at 1 C.?3?NCM 811 materials were prepared by solvothermal method.The effects of different process parameters such as solvent,reaction temperature and time on the crystalline phase and electrochemical properties of the materials were studied.The best process parameters were 1:1 volume ratio of glycol and water,200 ? solvothermal temperature,and 12 h reaction time,the material had good crystallinity and the first discharge specific capacity was 133.1 m Ah g-1 at 1 C.?4?Ti modified NCM 811 material was prepared by solvothermal.The effects of different amount of double titanium modification on the phase,morphology and electrochemical properties of the material were studied.When the modified amount of titanium was 0.01 mol,the content of Ni2+ in the lithium layer decreased from 7.9 %?pure sample?to 3.4 %.The surface of NCM 811 coated with proper proportion Ti O2 had a low residual lithium salt content.The first cycle coulomb efficiency of the modified NCM 811 was 84.16 % at 0.5 C,and the discharge capacity of 144.4 m Ah g-1 at 5 C.