Positive material of high-voltage lithium ion battery, lithium ion battery and preparation method thereof

Abstract

The invention belongs to the technical field of lithium ion batteries and relates to a positive material of a high-voltage lithium ion battery, the lithium ion battery and a preparation method thereof. The positive material of the high-voltage lithium ion battery is prepared from the following raw materials in percent by weight: 92%-98% of positive active substance with a single-crystal structure,1%-4% of conductive agent and 1%-4% of binding agent, wherein the structural formula of the positive active substance with the single-crystal structure is LiNixCoyMn1-x-yO2; in the formula, x is morethan 0.4 and less than 0.9, y is more than 0 and less than 0.4, and 1-x-y is more than 0 and less than 1. The positive material has good structural stability and higher heat stability in the processof high-voltage circulation, so that the defects of easy structure change and the like of the existing positive material when in use under a high voltage due to poor heat stability are relieved.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a high-voltage lithium battery cathode material, a lithium ion battery and a preparation method thereof. Background technique [0002] In the existing secondary battery system, lithium-ion batteries are currently the most competitive secondary batteries in terms of development space and technical indicators such as life, specific energy, working voltage and self-discharge rate. The key material of lithium-ion batteries is the cathode material, which accounts for about 30% of the cost of lithium-ion batteries. At present, the positive electrode materials used in lithium-ion batteries on the market mainly include lithium cobalt oxide, lithium iron phosphate, lithium manganese oxide, and nickel-cobalt lithium manganese oxide (NCM) ternary materials. [0003] With the increase of electric vehicles, hybrid vehicles, cordless power tools and military applicat...

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Problems solved by technology

[0004] The most studied high-voltage cathode material is the spinel oxide LiNi 0.5 mn 1.5 o 4 , but the key problem of this material is that it is not easy to produce a product with a single phase and good chemical stability

The usual solid-phase method or liquid-phase method tends to cause oxygen defects in the spinel structure during high temperature treatment. The material is not synthesized according to the stoichiometric ratio, and Li x Ni 1－x O and other impurity phases, Mn 3+ It does not completely disappear, which makes the phase change serious during the charging and discharging process, which is easy to cause problems such as capacity attenuation and poor high-rate discharge performance.

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