Synthesis And Modification Of Nickel-Rich Ternary Cathode Material For Lithium-ion Battery

With regard to the synthetic method,co-precipitation route is the most commonly used technique for synthesis of high performance LiNi_0.6Co_0.2Mn_0.2O₂?NCM622?material.However,numerous procedures increase complexity of the manufacturing process.Moreover,the co-precipitation technique produces large amounts of waste water containing transition metal ions,resulting in some environmental issues.Doping and coating methods are commonly used to improve the electrochemical properties of cathode material.Among them,doping improves the electrochemical properties of material by introducing other elements into the crystals to form more stable chemical bonds and so on.The NCM622 was synthesized by a simple rheological phase process in this paper,and the effect of different lithium salt ratio on the electrochemical performance and physical structure was investigated.It reveals that the ratio of 1.15 sample has the highest initial discharged capacities of 177.1mAh/g,due to the lowest degree of cation mixing.However,the ratio of 1.05 sample showed the best cycling stability and rate capability,which is correlated to its small particle size and highly ordered structure.Phosphorus and fluorine co-doped Nickel-rich cathode material NCM622 is doped with LiPF₆.Thermogravimetry and differential analysis confirmed that reaction temperature was about 500°C,physical characterization showed that LiPF₆ doping did not change the crystal shape of material,but increased the resistivity of the material.Electrochemical results show that doping LiPF₆ can reduce initial discharge capacity and initial coulomb efficiency,and improve the cycling performance of the material at high discharge rate.It reveals that the sample with a ratio of 3%has the highest initial discharged capacities of 157.8mAh/g and the best cycling stability of 92.8%at 0.5C,compared with this,the raw material capacities of 154mAh/g and cycling stability of81.4%.The Nickel-rich cathode material NCM622 is doped with LiBF₄ as raw material.It is found that the ordering degree and conductivity performance of the materials decrease.Electrochemical results show that the discharge capacity of LiBF₄-doped materials increases and then decrease with the charge-discharge cycles.Compared with the raw material discharged capacities of 168.2mAh/g,the sample with a ratio of 4%shows the highest discharged capacities of 178mAh/g at 0.1C.