High-voltage composite lithium cobaltate cathode material and preparation method and application thereof

Abstract

The invention discloses a high-voltage composite lithium cobaltate cathode material and a preparation method and application thereof. The composite lithium cobaltate cathode material comprises a particle core doped with gradient metallic elements and a coating layer having a spinel structure, wherein the particle core has an uneven surface. Further, a preparation method of the composite lithium cobaltate cathode material is also disclosed. The application of the composite lithium cobaltate cathode material is also disclosed. The method obtains gradient doped primary particles by primary sintering, and obtains the lithium cobaltate cathode material with a core layered structure and a shell spinel structure by secondary sintering. The method is simple in process and is controllable in operation procedure. The prepared lithium cobaltate material has good structural stability, high discharge capacity and excellent cycle performance at high voltage.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a high-voltage composite lithium cobalt oxide positive electrode material and a preparation method and application thereof. Background technique [0002] Lithium-ion batteries have the characteristics of light weight, high specific energy, no memory effect, small self-discharge, and long life. They are not only widely used in civil and military fields such as mobile phones, notebook computers, video cameras, and digital cameras, but also in electric vehicles, aerospace and energy storage have great development prospects. [0003] In recent years, with the continuous development of science and technology and the continuous improvement of the performance of mobile devices and communication devices, in order to meet people's needs for energy and safety, the development of positive electrode materials with higher voltage, higher energy density, and good cycl...

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Problems solved by technology

However, at a higher voltage, lithium cobalt oxide will cause structural instability as more lithium ions are extracted from the lattice. Excessive lithium ion extraction will cause the internal structure to collapse, affecting the service life of high-voltage lithium cobalt oxide.

[0005] In the prior art, CN104953096A treats the core of lithium cobaltate with acid solution to make the surface of the core uneven, then filters, washes repeatedly to remove acid, and dries, and then coats a layer of material on the basis of the core to form a core-shell structure of lithium cobaltate , this method needs to use acid liquid, and also uses water to remove acid, the waste liquid treatment is difficult, and the production cost is increased. At the same time, the coated shell part has a layered structure, and the high pressure resistance of the lithium battery layered structure is not as good as that of spinel. structure, which affects the application of high-voltage lithium cobalt oxide; CN109461891A uses nickel-manganese binary active materials for doping to stabilize the internal structure, and the surface coating layer has a spinel structure of nickel-manganese lithium oxide, which can effectively avoid the inert elements. capacity loss, and because the spinel structure is more resistant to high voltage than the layered structure, it overcomes the Li in the inert cladding layer + The conductivity is poor, but the surface coating layer of this material particle is a spinel structure and the inner matrix part is a layered structure. The spinel structure and the layered structure belong to two different structures, and there is a boundary between the two, resulting in The structure of the material is not stable enough, charging and discharging at high voltage will easily lead to structural separation, affecting the performance of the battery, thus affecting the application of high-voltage lithium cobalt oxide

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