High-nickel cathode material and preparation method thereof and lithium-ion battery

Abstract

The invention provides a high-nickel cathode material, which comprises a base material and a lithium cobaltate layer, wherein the base material is a compound as shown in a formula I; and the lithium cobaltate layer coats the surface of the base material. The high-nickel cathode material provided by the invention comprises the lithium cobaltate layer; the lithium cobaltate layer can interact with the residual lithium on the surface of the base material, so that the alkali content of the surface of the high-nickel cathode material provided by the invention is relatively low; meanwhile, the lithium cobaltate layer can strengthen intercalation/deintercalation of lithium ions in battery charging and discharging processes; side reaction of the cathode material and electrolyte can also be suppressed; and the high-nickel cathode material provided by the invention has relatively high energy density and long cycle life, so that a lithium-ion battery prepared from the high-nickel cathode material has relatively high capacity, cycle performance and heat stability. The invention further provides a preparation method of the high-nickel cathode material and the lithium-ion battery.

Description

technical field [0001] The invention relates to the technical field of positive electrode materials, in particular to a high-nickel positive electrode material, a preparation method thereof, and a lithium ion battery. Background technique [0002] In recent years, the successful commercialization of Tesla electric vehicles has driven the attention of the lithium battery industry to high-nickel cathode materials. High-nickel cathode materials for lithium-ion batteries (such as nickel-cobalt lithium manganese oxide cathode materials) are comparable to ordinary lithium cobalt oxide cathode materials. It has the advantages of high specific capacity and low price, but due to the similar particle size of Li and Ni ions, it is easy to mix Li and Ni ions during the preparation process, which will lead to high initial irreversible capacity and thermal stability of high-nickel cathode materials. The disadvantages of poor performance and accelerated degradation of cycle performance lim...

AI Technical Summary

Problems solved by technology

[0003] Due to the low sintering temperature of high-nickel cathode materials, the residual alkali content on the surface is relatively high, and the residual alkali content on the surface increases with the increase of nickel content, so that the high-nickel cathode materials are extremely susceptible to moisture and water absorption in the air , causing the viscosity of the material to increase or even appear jelly-like during pulping, making the processing more difficult; moreover, the residual alkaline substances on the surface of the high-nickel positive electrode material will bring moisture into the battery, causing a large loss to the battery and prone to side reactions. The internal resistance of the battery increases, resulting in a decrease in battery performance, and may also cause the battery to appear flatulence

[0004] The coating and doping methods provided by the prior art cannot effectively solve the problem of high alkalinity on the surface of high-nickel positive electrode materials. Generally, in actual production, washing is used to reduce the amount of alkalinity, so as to improve the processing performance of the material; but In the process of water washing, it is often inevitable to cause a certain degree of capacity loss and electrochemical performance degradation of the positive electrode material, because the surface of the high-nickel positive electrode material is very sensitive to moisture, and chemical delithiation reactions are prone to occur, resulting in the destruction of the surface crystal structure. The capacity of the high-nickel cathode material is easy to decrease, and the washed material is more likely to absorb water than the unwashed material

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