A kind of aqueous coating method of high-voltage lithium cobalt oxide cathode material

Abstract

Disclosed is an aqueous coating method for a high-voltage lithium cobalt oxide positive electrode material. Specifically steps comprise: weighing and taking pure water and adding the pure water to a ball mill to perform ball milling, after ball milling is complete, starting a cycle, and then separately weighing and taking a dispersant and a metal ion compound and adding the dispersant and the metal ion compound to the ball mill to perform cyclic ball milling and dispersion, to complete preparation of a primary slurry; then weighing and taking lithium cobalt oxide and adding the lithium cobalt oxide to the ball mill to perform ball milling and dispersion, to complete preparation of a secondary slurry; after dispersion, the slurry is added to a vacuum drying machine by using a mortar pump to perform drying; and after drying, adding the material to a kiln to perform secondary sintering; and performing screening and metal elimination on the material after secondary sintering, to obtain a required material. For the preparation method disclosed in the present invention, a layer of oxide is coated on a surface of lithium cobalt oxide, thereby improving charging and discharging voltages of a lithium cobalt oxide positive electrode material, and overcoming a defect of undesirable cycling stability of the material during high-voltage charging and discharging, so that the material of the present invention can be used as a 4.4-V positive electrode lithium cobalt oxide material of a lithium ion battery.

Description

technical field [0001] The invention belongs to the technical field of lithium batteries, in particular to an aqueous coating method for a high-voltage lithium cobalt oxide cathode material. Background technique [0002] Among lithium-ion cathode materials, lithium cobalt oxide is widely used due to its high working voltage and energy density, easy synthesis and fast charge and discharge. However, in the case of deep charge and discharge (charging voltage above 4.3V), there are obvious defects in the structural stability and safety performance of lithium cobalt oxide. [0003] In order to solve the above-mentioned problems existing in lithium cobalt oxide, the method currently adopted is surface coating. Through a certain coating technology, a layer of material is uniformly coated on the surface of the lithium cobalt oxide positive electrode material, which can effectively prevent the direct contact between the active material and the electrolyte, thereby effectively inhibi...

AI Technical Summary

Problems solved by technology

[0006] This process has the following disadvantages: (1) The primary slurry is a suspension. Due to the insufficient complexing ability of simple organic matter to water-insoluble metal ion compounds, the metal ion compounds are prone to sedimentation during the ball milling process, so that during the coating process The segregation of metal ion compounds is easy to occur, causing the problem of uneven coating

(2) Due to the limited complexation of simple organic matter, a large amount of organic matter needs to be used in the slurry preparation process. The total molar weight of water-soluble organic matter in the patent is 50-70% of the molar weight of lithium cobaltate. Decomposed into CO2 and H2O in the process, it will not improve the performance of lithium cobaltate, and the large use of organic matter is a waste of raw materials

(3) This process needs to mix metal ion compounds and water-soluble organic matter before making a slurry, which increases the process and does not utilize industrial production

(4) The ball milling time of the primary slurry in this process is 2 to 5 hours, and the ball milling time of the secondary slurry is 6 to 12 hours. The ball milling time is long, which is not conducive to industrial production, and the long-term ball milling will cause great wear and tear on the equipment and increase the introduction of foreign matter product possibility

And the long-term ball milling of the secondary slurry will damage the surface morphology and internal structure of lithium cobaltate particles, that is, the particle size mentioned in the patent is finer, which will affect the physical and electrochemical properties of the product

Images