Method for preparing lithium-rich solid solution cathode material with lithium, nickel, manganese and cobalt system through partial dissolution

Abstract

The invention relates to a method for preparing a lithium-rich solid solution cathode material with a lithium, nickel, manganese and cobalt system through partial dissolution. The method is characterized by comprising the following steps of: weighing a lithium compound, a nickel compound, a manganese compound and a cobalt compound in a molar ratio of lithium ions to nickel ions to manganese ions to cobalt ions of (1.1+0.90.x):(1-x).y:(x+z-x.z):(1-x).k; weighing weak organic acid with the mole number of more than or equal to (x+z-x.z) and less than or equal to x+(1-x).(z+y+k); mixing the weighed nickel compound, manganese compound and cobalt compound, adding a wet grinding medium and the weak organic acid, performing wet grinding and mixing, adding the lithium compound, and performing wet grinding and mixing again to obtain a precursor 1; and drying the precursor 1, putting the precursor 1 in air, oxygen-rich gas or pure oxygen atmosphere, and performing two-section sintering to prepare the lithium-rich solid solution cathode material. The electrode material prepared by the method has uniform composition, high discharge performance, and high discharge cycle performance particularly under the high-current condition.

Description

technical field [0001] The invention belongs to the technical field of battery electrode material preparation, and specifically relates to a preparation method of a lithium-rich solid solution positive electrode material that can be used in lithium nickel manganese cobalt systems of lithium batteries, lithium ion batteries, polymer batteries and supercapacitors. technical background [0002] Spinel LiMn 2 o 4 It has the characteristics of high working voltage, low price, and environmental friendliness, but the reversible capacity of the positive electrode material is low, and the discharge point capacity is only 90-100mAh / g when charging and discharging at a rate of 1C; at high temperatures, the discharge capacity of the positive electrode material will change with the Rapid decay with the charge-discharge cycle. [0003] Lithium-rich solid solution cathode material Li 2 MnO 3 ·Li[Ni 1 / 3 co 1 / 3 mn 1 / 3 ]O 2 It shows the advantages of high specific capacity, good therm...

AI Technical Summary

Problems solved by technology

The preparation process has many preparation steps, and the preparation process needs to use a large amount of washing water, which increases water pollution

When preparing carbonate precipitation by co-precipitation method, the precipitation solubility product of nickel, manganese and cobalt ions is larger; completely (hydroxide precipitates easily with OH - Or ammonia forms a complex and increases the solubility of hydroxide), which causes the stoichiometric ratio of the composition of the final product to be difficult to accurately control, resulting in the instability of the electrochemical performance and high-current discharge performance of the sample (Editor-in-Chief, Wuhan University, Analytical Chemistry (Second Edition), Higher Education Press, October 1982, Beijing: Pages 14 to 17)

[0017] In summary, the energy-consuming and water-consuming preparation steps such as filtration and washing to be experienced during the preparation of the co-precipitation method, in addition, when prepared by the co-precipitation method, due to the hydroxide of manganese ions, cobalt ions, and nickel ions Or carbonate precipitation is not complete, making it difficult to control the stoichiometric ratio of the prepared product

The ordinary solid phase sintering method, in which the reactants are simply mixed by ball milling and then sintered, has problems such as uneven mixing of the reactants and poor consistency of the electrochemical properties of the reaction products.

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