a surface coating li 2 tio 3 Lithium cobaltate-based composite cathode material and preparation method thereof

Abstract

The invention discloses a lithium-cobalt-oxide-based composite positive material with surface coated with Li2TiO3. A titanium-containing lithium-cobalt-oxide-based composite material is used as a basal body, and the surface of the basal body is coated with Li2TiO3, wherein the mass ratio of Li2TiO3 to the positive material is 0.2 to 5 percent; a molecular formula of the titanium-containing lithium-cobalt-oxide-based composite material is xLi2TiO3.(1-x)LiCoO2, wherein x is more than or equal to 0.01 and less than or equal to 0.10. The lithium-cobalt-oxide-based composite positive material with surface coated with Li2TiO3 has excellent chemical properties under a high voltage, the voltage range is 3.0V to 4.6V, and when the current density is 20mA / g, the primary specific discharge capacity can reach more than 200mAh / g; when the current density is 1A / g, the specific discharge capacity can reach 190mAh / g; when the current density is 200mA / g, the capacity retention rate is more than 90 percent after 50 charge-discharge cycles.

Description

technical field [0001] The invention belongs to the field of positive electrode materials for lithium ion batteries, in particular to a surface-coated Li 2 TiO 3 Lithium cobaltate-based composite positive electrode material and preparation method thereof. Background technique [0002] Since the commercialization of lithium-ion batteries in 1990, its application range has been continuously expanded, ranging from portable electronic devices such as mobile phones, notebook computers, and digital cameras to electric vehicles, aerospace, and artificial satellites. In the composition of lithium-ion batteries, the cathode material is the most important component of lithium-ion batteries and the key to the development of lithium-ion energy storage devices. Lithium cobaltate is the earliest commercialized and still widely used cathode material for lithium-ion batteries. It has the advantages of high working voltage, good compatibility, and easy synthesis. Its theoretical capacity r...

AI Technical Summary

Problems solved by technology

Both the Chinese patent document CN101284681A and the US patent document US6555269B2 mention the use of doping with elements such as Mg and Ti to improve the high temperature performance and overcharge resistance of lithium cobaltate; however, the material particles are still exposed without surface coating treatment. In acidic electrolyte, thus affecting its cycle performance under high voltage

CN103779556A Chinese patent document proposes to improve the electrochemical performance of lithium cobaltate through doping and surface coating co-modification; but the coating material is an inactive phosphate, thereby reducing the conductivity of lithium cobaltate

In the non-patent literature (“Studies of LiCoO 2 coated with metal oxides”. Electrochemical and Solid-State Letters 6 (2003) A221-A224) proposed that coating metal oxides can improve the cycling performance of lithium cobalt oxide; Phase transition leads to material structural instability

The above-mentioned bulk phase doping modification needs to replace part of the cobalt element in lithium cobalt oxide, and the surface coating modification adopts inactive material coating. Although it can indeed improve some performance defects of lithium cobalt oxide, it still makes the capacity of the battery somewhat reduce

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