Composite cladded lithium ion cathode material, and preparation method thereof

Abstract

The invention discloses a composite cladded lithium ion cathode material, and a preparation method thereof. According to the composite cladded lithium ion cathode material, Li(NiCoMn)O2 and / or Li(NiCoAl)O2 is taken as a matrix; the surface of the matrix is cladded with an electrically conductive cladding layer; the electrically conductive cladding layer comprises a lithium fast ion conductor material, and optionally comprises an electronic conductor material. The preparation method comprises following steps: 1, the lithium fast ion conductor or raw materials of the lithium fast ion conductor are dispersed in a solvent, and optionally, an electronic conductor material or raw materials of the electronic conductor material are dispersed in the solvent so as to obtain an electrically conductive cladding layer solution; 2, a cathode material is dispersed in the electrically conductive cladding layer, and stirring is carried out so as to obtain a mixed solution; 3, the mixed solution is stirred, and is subjected to distillation with stirring so as to obtain a dried powder; and 4, the dried powder is subjected to annealing, smashing, and sieving successively so as to obtain the compositecladded lithium ion cathode material. The composite cladded lithium ion cathode material possesses following advantages: cracking is not easily caused, the electrical properties are excellent, the preparation method is simple, and is convenient for industrialized production.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, and in particular relates to a lithium ion battery positive electrode material, in particular to a composite coated lithium ion battery positive electrode material and a preparation method thereof. Background technique [0002] At present, the commonly used lithium ion cathode materials in the market mainly include lithium cobaltate, lithium manganese oxide, lithium iron phosphate and ternary cathode materials with different ratios. Due to the high cost, lithium cobalt oxide cathode materials are mainly used in the production of batteries for 3C electronic products. In the electric vehicle market, ternary cathode materials occupy a large proportion. [0003] However, the particle morphology of ternary cathode materials on the market is mostly spherical secondary particles, which are formed by agglomeration of primary particles. During the electrochemical cycle of this type of material, due ...

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Problems solved by technology

Taking nickel-cobalt lithium aluminate as an example, as the number of charge and discharge increases, cracks will eventually occur between the primary particles, and the formation of cracks will cause the electrolyte to enter the cracks and increase the reaction area; continue the electrochemical cycle with the cycle As the number of times increases, the cracks continue to expand, and even run through the entire secondary particle, causing the secondary particle to break or even break, deteriorating battery performance

[0004] Moreover, the ternary cathode material Ni in the delithiated state 4+ It is very unstable and highly reactive. Therefore, it is easy to cause the reaction between the electrode and the electrolyte to generate high interfacial internal resistance, especially at high nickel content, which leads to rapid decay of material capacity and poor cycle performance. Therefore, it is necessary to The surface of the ternary cathode material is coated to prevent the reaction between the electrode and the electrolyte

[0005] In the prior art, it is disclosed that the surface of the ternary positive electrode material is coated with metal oxide, but the poor conductivity of the metal oxide leads to poor conductivity of the positive electrode material and a decrease in capacity.

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