CN-121282139-B - Lithium aluminum phosphate composite coated modified lithium cobalt oxide positive electrode material and preparation method thereof

CN121282139BCN 121282139 BCN121282139 BCN 121282139BCN-121282139-B

Abstract

The invention provides a lithium aluminum titanate phosphate compound coated modified lithium cobalt oxide anode material which is of a core-shell structure and comprises a doped lithium cobalt oxide core material in the core-shell structure and a coating layer formed on the surface of the doped lithium cobalt oxide core material, wherein the chemical formula of the doped lithium cobalt oxide core material is LiCo 1‑a‑b‑c Mg a Al b Ce c O 2 , and the coating layer comprises lithium aluminum titanate phosphate, cerium titanate, cerium lithium oxide and cerium lithium phosphate. The lithium aluminum titanium phosphate composite coated modified lithium cobalt oxide anode material overcomes the defect of suddenly reduced material performance under high-temperature and high-pressure application when the lithium aluminum titanium phosphate material is coated independently. The oxygen vacancies and the coating structure provided by the composite coating layer of the lithium aluminum titanium phosphate, the cerium titanate, the cerium lithium cerium oxide and the lithium cerium phosphate ensure the structural continuity between the reinforcement phase and the coating layer and the conductivity of the fast ion conductor, so that the material has good cycle retention rate at high temperature and high pressure and maintains the capacity characteristic of the material.

Inventors

Zeng Zhidun
TU WEN
LI YIBO
Ran Maojin
WANG LIN
ZHU XIANXU
TANG CHAOHUI

Assignees

湖南美特新材料科技有限公司

Dates

Publication Date: 20260505
Application Date: 20250926

Claims (8)

1. The lithium aluminum titanium phosphate composite coated modified lithium cobalt oxide positive electrode material is characterized by being of a core-shell structure, and comprises a doped lithium cobalt oxide core material and a coating layer, wherein the doped lithium cobalt oxide core material is arranged in the core-shell structure; The chemical formula of the doped lithium cobalt oxide core material is as follows: liCo 1-a-b-c Mg a Al b Ce c O 2 , wherein, a is more than or equal to 0.001 and less than or equal to 0.005, b is more than or equal to 0.001 and less than or equal to 0.005 c is more than or equal to 0.005 and less than or equal to 0.001 and less than or equal to 0.010; The coating layer comprises titanium aluminum lithium phosphate, cerium titanate, cerium lithium oxide and cerium lithium phosphate, wherein the chemical formula of the titanium aluminum lithium phosphate is Li 1+x Al x Ti 1+1-x (PO 4 ) 3 , and x is more than or equal to 0.2 and less than or equal to 0.5; Cerium titanate has a chemical formula of Ce 1-y Ti 2+y O 6-z , y is more than or equal to 0.1 and less than or equal to 0.4,0.2 and less than or equal to z and less than or equal to 0.5, lithium cerium oxide phosphate has a chemical formula of Li 2 Ce m (PO 4 ) n O, m is more than or equal to 0.2 and less than or equal to 0.5, n is more than or equal to 0.2 and less than or equal to 0.5, and lithium cerium phosphate has a chemical formula of Li d CePO 4 and d is more than or equal to 0.2 and less than or equal to 0.8; the weight of the coating layer accounts for 0.1% -2% of the weight of the modified lithium cobalt oxide anode material.
2. The lithium aluminum titanium phosphate composite coated modified lithium cobalt oxide positive electrode material according to claim 1, wherein the content of the lithium aluminum titanium phosphate in the coating layer is 55% -65%.
3. The lithium aluminum titanium phosphate composite coated modified lithium cobalt oxide positive electrode material according to claim 1, wherein the weight of the coating layer accounts for 0.2% -1.5% of the weight of the modified lithium cobalt oxide positive electrode material.
4. The lithium aluminum titanium phosphate composite coated modified lithium cobalt oxide cathode material according to claim 1, wherein the particle size of the doped lithium cobalt oxide core material is controlled to be D50<7 μm.
5. The lithium aluminum titanium phosphate composite coated modified lithium cobalt oxide positive electrode material according to claim 1, wherein cerium titanate in the coating layer accounts for 27% -35% of the content of the coating layer.
6. The lithium aluminum titanium phosphate composite coated modified lithium cobalt oxide positive electrode material according to claim 1 is characterized in that the preparation method of the lithium aluminum titanium phosphate composite coated modified lithium cobalt oxide positive electrode material comprises the following steps of (1) mixing a magnesium source, an aluminum source, a cerium source, a cobalt source and a lithium source, sintering the mixture in an oxygen-containing atmosphere at a constant temperature of minus 1 to minus 4kpa and 950 ℃ to 1080 ℃ for 8 to 15 hours to form a sintered doped lithium cobalt oxide core material, and (2) mixing the mixed lithium aluminum phosphate composite coated modified lithium cobalt oxide positive electrode material with an aluminum source, an ammonium phosphate salt, a titanium source and a cerium source at a granularity of D50<7 mu m and sintering the mixture in an oxygen-containing atmosphere for 15 to 20 hours at a temperature of minus 650 ℃ to 720 ℃ to obtain the lithium aluminum titanium phosphate composite coated modified lithium cobalt oxide positive electrode material.
7. A preparation method of the lithium aluminum titanium phosphate composite coated modified lithium cobalt oxide positive electrode material according to any one of claims 1-6 is characterized by comprising the following steps of (1) mixing a magnesium source, an aluminum source, a cerium source, a cobalt source and a lithium source, then sintering the mixture in an oxygen-containing atmosphere at a constant temperature of negative pressure of-1 to-4 kpa and 950 ℃ for 8-15 hours to form a sintered doped lithium cobalt oxide core material, and (2) mixing the mixed lithium aluminum source, ammonium phosphate salt, titanium source and cerium source with the granularity of D50<7 mu m, and sintering the mixture in an oxygen-containing atmosphere at a temperature of negative pressure of-1 to-4 kpa and 650 ℃ to 720 ℃ for 15-20 hours to obtain the lithium aluminum titanium phosphate composite coated modified lithium cobalt oxide positive electrode material.
8. The preparation method of the lithium aluminum titanium phosphate composite coated modified lithium cobalt oxide positive electrode material according to claim 7, wherein in the step (1), a magnesium source, an aluminum source and a cerium source are corresponding oxides or hydroxides, a cobalt source is tricobalt tetraoxide, a lithium source is lithium carbonate, and in the step (2), the aluminum source, the titanium source and the cerium source are corresponding oxides, and an ammonium phosphate is diammonium hydrogen phosphate or monoammonium phosphate.

Description

Lithium aluminum phosphate composite coated modified lithium cobalt oxide positive electrode material and preparation method thereof Technical Field The invention relates to a lithium cobalt oxide positive electrode material, in particular to a titanium aluminum lithium phosphate compound coated modified lithium cobalt oxide positive electrode material and a preparation method thereof. Background The lithium ion battery has wide application range nowadays, the main application range of the lithium battery taking lithium cobaltate as a battery anode material is 3C small electricity market, the development market of 3C equipment brings higher requirements on energy density, cycle life and the like, and the application scene is more diversified and extends to high voltage, high temperature, low temperature and the like. Compared with the normal temperature application environment, the ion transmission rate is accelerated at high temperature, the subsequent cycle retention rate is obviously attenuated, possible reasons include collapse of a high temperature acceleration structure, higher polarization voltage and higher internal resistance of the material surface caused by high temperature, and a conceivable solution for the situation comprises adding interlayer spacing by doping large-particle-size particles and carrying out surface modification on the particle surface by using an additional coating material, so that the material forms a CEI film with more stable, compact and more suitable thickness in the charge and discharge process. However, the cycle performance of the existing magnesium-aluminum doped lithium cobalt oxide battery anode material on a high-temperature line needs to be improved. Disclosure of Invention The invention aims to overcome the defects in the prior art and provide a titanium aluminum lithium phosphate compound coated modified lithium cobalt oxide positive electrode material and a preparation method thereof. In order to achieve the aim, the technical scheme adopted by the invention is that the lithium aluminum titanium phosphate composite coated modified lithium cobalt oxide anode material is of a core-shell structure and comprises a doped lithium cobalt oxide core material in the core-shell structure and a coating layer formed on the surface of the doped lithium cobalt oxide core material; The chemical formula of the doped lithium cobalt oxide core material is as follows: liCo 1-a-b-cMgaAlbCecO2, wherein, a is more than or equal to 0.001 and less than or equal to 0.005, b is more than or equal to 0.001 and less than or equal to 0.005 c is more than or equal to 0.005 and less than or equal to 0.001 and less than or equal to 0.010; The coating layer comprises titanium aluminum lithium phosphate, cerium titanate, cerium lithium oxide and cerium lithium phosphate, wherein the chemical formula of the titanium aluminum lithium phosphate is Li 1+xAlxTi1+1-x(PO4)3, and x is more than or equal to 0.2 and less than or equal to 0.5; Cerium titanate has a chemical formula of Ce 1-Ti2+y O6-z, y is more than or equal to 0.1 and less than or equal to 0.4,0.2 and less than or equal to z and less than or equal to 0.5, lithium cerium oxide phosphate has a chemical formula of Li 2Cem(PO4)n O, m is more than or equal to 0.2 and less than or equal to 0.5, n is more than or equal to 0.2 and less than or equal to 0.5, and lithium cerium phosphate has a chemical formula of Li dCePO4 and d is more than or equal to 0.2 and less than or equal to 0.8; the weight of the coating layer accounts for 0.1% -2% of the weight of the modified lithium cobalt oxide anode material. The lithium aluminum titanium phosphate composite coated modified lithium cobalt oxide anode material is of a core-shell structure, the magnesium, aluminum and cerium doped lithium cobalt oxide core material is arranged in the core-shell structure, the structural stability of the material can be improved, the bulk phase structure of lithium cobalt oxide particles can be improved, the magnesium ion and aluminum doped support interlayer structure improves the lattice stability, meanwhile, cerium ion doping utilizes the strong oxidation resistance and larger ion radius to introduce more oxygen vacancies after entering the bulk phase structure, the ion mobility and the transmission rate of lithium ions in the charging and discharging process are improved, and a compact composite coating layer is generated through the sintering reaction of a coating layer additive, so that the lithium aluminum titanium phosphate composite coated modified lithium cobalt oxide anode material has good structural stability. In-situ generation of lithium aluminum titanium phosphate, cerium titanate, cerium lithium cerium oxide and lithium cerium phosphate on the surfaces of lithium cobalt oxide particles, wherein the chemical formula of the cerium lithium oxide is Li 2Cem(PO4)n O, namely, the cerium lithium oxide is oxygen to replace part of the phosphate radical, the tit