Composite positive electrode material, positive electrode sheet, preparation method of positive electrode sheet, and lithium ion battery

Abstract

The invention relates to the field of lithium ion batteries and discloses a composite cathode material, a cathode sheet, a preparation method of the cathode sheet, and a lithium ion battery. The material includes first nickel-cobalt-lithium composite oxide which is a secondary particle spherical agglomerate, wherein the primary particles in the secondary particle spherical agglomerate have a particle diameter of 200 to 400 nm, and the first nickel-cobalt-lithium composite oxide has an average particle diameter of 10 to 12[mu]m; second nickel-cobalt-lithium composite oxide which is a single crystal-like material, wherein the primary particles in the second nickel-cobalt-lithium composite oxide have a particle diameter of 600 to 2000 nm, and the second nickel-cobalt-lithium composite oxide has an average particle diameter of 6.5 to 8.5[mu]m; and a LMFP compound which is a single crystal-like material, wherein the primary particles in the LMFP compound have a particle diameter of 50 to 200 nm, and the LMFP compound has an average particle diameter of 0.8 to 2[mu]m. Applying the technical solution is beneficial to improving the energy density and the safety performance of the lithium ion battery.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, and discloses a composite positive electrode material, a positive electrode sheet, a preparation method for the positive electrode sheet, and a lithium ion battery. Background technique [0002] Since the commercialization of lithium-ion batteries, because of their advantages such as high energy density, high battery voltage, long cycle life and no memory effect, they have not only rapidly become energy storage devices used in various fields of life, but also attracted experts and researchers. broad interests. With the development of electrical and electronic equipment, especially the rapid development of electric vehicles, the energy density and power density of existing lithium-ion batteries cannot meet the energy demand. Therefore, finding and preparing materials with high energy density is an urgent problem. [0003] Ternary materials have great advantages in compaction density, platform...

AI Technical Summary

Problems solved by technology

With the development of electronic and electrical equipment, especially the rapid development of electric vehicles, the energy density and power density of existing lithium-ion batteries cannot meet the energy demand, so finding and preparing materials with high energy density is an urgent problem

[0003] The compaction density, platform voltage and gram capacity of ternary materials have great advantages, but the thermal stability of ternary materials is poor, and oxygen is easily released in the delithiated state, resulting in poor safety performance of this type of battery.

For example, the high-nickel ternary material NCM811 has a capacity of up to 200mAh / g, a voltage platform of 3.6V, and a compaction density of 3.4g / cm 3 , but the NCM811 in the delithiated state begins to release oxygen at around 235°C, which directly aggravates the thermal runaway degree of the battery, and has application safety problems, which limits the promotion of ternary materials as cathode materials

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