Positive electrode active material for lithium secondary battery

Abstract

Disclosed herein is a cathode active material based on lithium nickel-manganese-cobalt oxide represented by Formula 1, wherein an ion-conductive solid compound and conductive carbon are applied to a surface of the lithium nickel-manganese-cobalt oxide. A lithium secondary battery having the disclosed cathode active material has improved rate properties and high temperature stability, in turn embodying excellent cell performance.

Description

technical field [0001] The present invention relates to a positive electrode active material for a lithium secondary battery, more particularly, to a positive electrode active material based on lithium nickel-manganese-cobalt oxide represented by formula 1, wherein the lithium nickel-manganese-cobalt oxide The surface is coated with ion-conducting solid compounds and conductive carbon. Background technique [0002] With the technological advancement and demands of mobile devices, the demand for secondary batteries as energy sources has increased dramatically. Among such secondary batteries, lithium secondary batteries having high energy density and operating potential, long life cycle, and reduced self-discharge are widely used in the related art. [0003] For positive electrode active materials for lithium secondary batteries, lithium-containing cobalt oxides (LiCoO 2 ). In addition, lithium-containing manganese oxides such as LiMnO with a layered crystal structure can a...

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Problems solved by technology

[0004] Among such cathode active materials, although LiCoO with excellent physical properties such as cycle performance is widely used 2 , but this material suffers from disadvantages including low safety, high cost due to scarcity of cobalt as a natural resource, limitations in large-scale use as a power source in electric vehicle applications, etc.

The above characteristics can cause serious handling problems in battery manufacturing

[0010] Fourth, with LiCoO 2 The manufacturing method is different, and high-quality LiNiO cannot be prepared by simple solid-state reaction 2

However, in the case of using the oxide for a long period of time, the cycle performance is drastically deteriorated and other problems such as swelling due to gas generation in the battery, decrease in chemical stability, etc. cannot be sufficiently overcome.

[0012] It is considered that the reason for the above fact is that the nickel-based lithium transition metal oxide is in the form of secondary particles obtained by aggregation of small primary particles; therefore, lithium ions are transported to the surface of the active material and interact with moisture or CO in the air. 2 reaction, resulting in impurities such as Li 2 CO 3 , LiOH, etc.; impurities generated by residues remaining after the production of nickel-based lithium transition metal oxides may reduce the capacity of the single cell; or the impurities may be decomposed inside the battery to generate gas, thereby causing battery swelling

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