Positive electrode material, preparation method thereof, and battery

Abstract

The invention provides a positive electrode material, a preparation method thereof, and a battery. The positive electrode material includes: a substrate; a first cladding layer, which is coated on the surface of the substrate in a discrete island form; and a second cladding layer, which is coated on the first cladding layer and the surface of the substrate in a continuous layered form . The positive electrode material of the present invention has the characteristics of low surface residual lithium content, small specific surface area, and high surface structure stability, which can not only effectively improve the problem that the positive electrode material is easily broken under pressure, but also effectively reduce the side reaction between the positive electrode material and the electrolyte , reduce the gas production of the battery, and improve the storage performance of the battery.

Description

technical field [0001] The invention relates to the field of batteries, in particular to a positive electrode material, a preparation method thereof, and a battery. Background technique [0002] Cathode materials, especially ternary materials, have attracted extensive attention due to their high capacity and low cost. However, in practical applications, the surface structure of the positive electrode material is unstable and has a strong oxidation activity, which is very easy to cause side reactions with the electrolyte, thereby easily deteriorating the storage performance of the battery. [0003] Since the positive electrode material will add excess lithium salt during the preparation process to compensate for the loss of lithium caused by the sintering process, there will be a small amount of Li remaining on the surface of the prepared positive electrode material, which will be replaced by Li at high temperature. 2 Exists in the form of O, when the temperature drops to ro...

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Problems solved by technology

[0005] The first method is to wash the positive electrode material with water to remove the residual lithium on the surface of the positive electrode material and reduce the high-temperature gas production caused by residual lithium. However, after this method, the specific surface area of ​​the positive electrode material increases significantly, and the side reaction between the positive electrode material and the electrolyte is obvious. increase, unable to effectively suppress battery gas production

[0006] The second is to directly coat the surface of the positive electrode material to avoid direct contact between the positive electrode material and the electrolyte, and to suppress the occurrence of side reactions. limited effect

[0007] The third method is to wash the positive electrode material with water, and then perform high-temperature coating treatment on the positive electrode material to reduce the specific surface area of ​​the positive electrode material. However, the high-temperature coating treatment will easily lead to the dissolution of bulk lithium in the positive electrode material, and then the residual lithium content on the surface of the positive electrode material will increase. It is still high, and it cannot effectively suppress battery gas production

[0008] In addition, since the positive electrode material is usually in the form of secondary particles formed by the agglomeration of primary particles, the compressive strength is poor, and the specific surface area of ​​the positive electrode material increases significantly after crushing, resulting in an increase in the contact area with the electrolyte, and the gas production problem of the battery is further aggravated

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