High-voltage lithium cobalt oxide cathode material for lithium-ion battery and preparation method of high-voltage lithium cobalt oxide cathode material

Abstract

The invention discloses a high-voltage lithium cobalt oxide cathode material for a lithium-ion battery and a preparation method of the high-voltage lithium cobalt oxide cathode material. The high-voltage lithium cobalt oxide cathode material is prepared from a doped lithium cobalt oxide matrix and a coating on the surface of the doped lithium cobalt oxide matrix, wherein a general formula of the doped lithium cobalt oxide matrix is Li<x>Co<1-y>M<y>O<2-z>N<z>; the general formula of the coating is LiNi<x'>Co<y'>Al<z'>O<2>; and the preparation method comprises the following steps: firstly, obtaining the lithium cobalt oxide matrix Li<x>Co<1-y>M<y>O<2-z>N<z> through once sintering; secondly, preparing a lithium cobalt oxide cathode material precursor coated with Ni<x'>Co<y'>Al<z'>(OH)<2> on the surface by liquid-phase co-precipitation reaction; and finally obtaining the high-voltage lithium cobalt oxide cathode material through twice sintering. The high-voltage lithium cobalt oxide cathode material prepared by the method is good in processability and high in compaction density, has relatively high specific capacity and good cycle performance in a high-voltage state, and can be stably circulated at high voltage of 3.0V to 4.5V.

Description

technical field [0001] The invention relates to the field of positive electrode materials for lithium ion batteries, in particular to a high voltage lithium cobalt oxide positive electrode material for lithium ion batteries and a preparation method thereof. Background technique [0002] Lithium-ion batteries have been widely used in portable electronic products and mobile tools due to many advantages such as small size, light weight, high specific energy, and portability. LiCoO 2 As the most commonly used cathode material for commercial lithium-ion batteries, the theoretical specific capacity is 274mAh / g, but the actual capacity is only about 140mAh / g. This is because when the charge cut-off potential is lower than 4.2V, the structure changes corresponding to the extraction of lithium ions. for Li 1-x CoO 2 (0≤x≤0.5), only nearly half of the lithium ions can be extracted. In order to improve the LiCoO 2 The capacity of the battery, the charging cut-off voltage needs to ...

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Problems solved by technology

US20050130042 U.S. patent literature and non-patent literature (YuhongOh, DonggiAhn, SeunghoonNam, ByungwooPark.TheeffectofAl 2 o 3 -coating coverage on the electrochemical properties in LiCoO 2 thinfilms.JournalofSolidStateElectrochemistry, 2010,14(7):1235-1240) mentions the coating of LiCoO with alumina 2 Finally, the cycle performance and storage performance of lithium cobalt oxide at high voltage are improved. However, due to the A1 2 o 3 Equal oxides and LiCoO 2 The crystal structure of the battery is very different, the crystal matching is not good, and it is an inactive material oxide. After coating, the polarization of the material increases, and the capacity and rate performance of the battery decrease significantly.

No. CN104022280A Chinese patent document mentions that in pure Ni, Co binary system or in LiCoO 2 Surface coated Li p Ni x co y mn z o 2 , although the electrochemical performance of the material is improved when the working voltage is higher than 4.4V, when the battery is operated at a slightly high temperature (greater than 45°C), the protective effect of the coating layer on the substrate will be due to the dissolution of Mn And the gradual failure accelerates the deterioration of material properties under high voltage

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