Lithium ion battery composite positive electrode material, and preparation method and application thereof

Abstract

The invention discloses a lithium ion battery composite positive electrode material, and a preparation method and application thereof, and belongs to the technical field of lithium ion battery positive electrode materials. The lithium ion battery composite positive electrode material comprises a positive electrode base material, and a lithium-poor intermediate layer and a composite coating layer which sequentially coat the surface of the positive electrode base material, the lithium-poor-state intermediate layer is LixMx1Mn2-x1O4with a spinel structure, and the composite coating layer comprises an electronic conductor and an ionic conductor; and the positive electrode material is obtained by compositely coating the surface of the positive electrode base material with the composite coating layer consisting of the lithium-poor intermediate layer with a spinel structure, an electronic conductor and an ionic conductor. According to the composite positive electrode material disclosed by the invention, the positive electrode base material is coated by the lithium-poor intermediate layer and the composite coating layer, so that the rate capability and coulombic efficiency of the composite positive electrode material are effectively improved, and the cycle performance of the composite positive electrode material is improved.

Description

technical field [0001] The invention relates to the technical field of lithium-ion battery cathode materials, in particular to a lithium-ion battery composite cathode material and a preparation method and application thereof. Background technique [0002] At present, lithium-ion batteries have been widely used in consumer electronics equipment, energy storage equipment, and power tools. As one of the core materials of lithium-ion batteries, the positive electrode material has also carried out a lot of research on different application fields. At present, the commercialized positive electrode materials mainly include lithium cobalt oxide, lithium iron phosphate, lithium manganate, nickel cobalt lithium manganate and nickel Lithium cobalt aluminate. The above positive electrode materials will more or less have surface interface problems in lithium-ion batteries, such as side reactions between the electrolyte and the surface of the positive electrode material, and the interfac...

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Problems solved by technology

At present, the surface coating methods of positive electrode materials generally have the following types: First, metal oxides can be coated on the surface of positive electrode materials, and then a stable coating layer can be formed by annealing. This coating method can well isolate the positive electrode material from the electrolyte. However, the coating amount should not be too large, otherwise it will have a great negative impact on the electrochemical performance of the positive electrode material; another method is to coat the fast ion conductor on the surface of the positive electrode material, and the ions on the surface of the material Conduction has a very good helping effect, but the electronic conductance of fast ion conductors is usually poor, and the amount of such coating should not be too large; there is another method to coat the surface of positive electrode materials with electrochemically active substances, which will not Reduce the performance of the material, and even improve it to a certain extent, but the electrochemically active substances coated on the surface will still bring new surface and interface problems due to their certain activity.

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