Preparation And Surface Modification Of Spinel Lithium Manganate Cathode Materials

Spinel lithium manganate has always been an important part of the lithium-ion battery cathode system.Spinel lithium manganate is considered to be one of the most competitive cathode candidate materials for lithium-ion batteries because of its rich source and environmental friendliness.However,the inherent Jahn-Teller effect of Li Mn₂O₄ makes the capacity decay seriously,which affects the industrial application of the material.In this paper,the synthesis conditions of lithium manganate and the influencing factors in the preparation process were discussed by chemical precipitation method,and the modification of lithium manganate was studied in order to point out the optimal route for the preparation of lithium manganate by chemical precipitation method and improve its performance.According to the electrochemical test data,when the calcination time is10 h and the calcination temperature is 700°C,the lithium manganese oxide prepared by precipitation method has better crystal structure and excellent electrochemical performance.When the calcination temperature is 700°C,the first discharge capacity is101.3 m Ah·g^-1;when the calcination time is 10 h,the initial discharge capacity of the sample is 104.3 m Ah·g^-1.The results of electrochemical test data and software fitting data show that the synthesized lithium manganate has the best electrochemical performance when manganese chloride is used as manganese source and the amount of ammonium bicarbonate precipitant is 4.0 times.The initial discharge capacity of the sample synthesized with manganese chloride as manganese source is 108.9 m Ah·g^-1.In the cyclic impedance test,it has the smallest polarization degree and the fastest lithium-ion diffusion rate(1.998×10^-14 cm²·s^-1).When the amount of precipitant is 4.0 times,the sample has a good crystal structure and surface morphology.In the charge-discharge test,the first discharge capacity is 108.5 m Ah·g^-1.In addition,it can be seen from the rate charge and discharge analysis that the cycle performance of the oxide-coated lithium manganate sample at high rates has been improved,and the initial discharge capacity has reached 104.7 m Ah·g^-1.After 50 cycles,the 1C capacity retention rate is 87%,while the uncoated lithium manganate is only80.6%,which effectively improves the cycle instability and poor rate performance of lithium manganate.