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Modified cathode active material, preparation method of modified cathode active material and lithium secondary battery

A positive electrode active material and a positive electrode active material technology are applied in the field of lithium secondary batteries, modified positive electrode active materials and their preparation, which can solve the problem of not having electronic conductivity and ionic conductivity, and reducing the kinetic performance of lithium ion secondary batteries. , increase the overall impedance of lithium-ion secondary batteries, etc., to achieve the effect of improving dynamic performance, improving cycle and storage life, and reducing impedance value

Inactive Publication Date: 2018-07-17
CONTEMPORARY AMPEREX TECH CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the commonly used method is to coat the surface of the positive electrode active material with oxides of simple structure (such as TiO 2 , Nb 2 o 5 、Al 2 o 3 , ZrO 2 , Y 2 o 3 , B 2 o 3 etc.), this kind of coating method can reduce the oxidation of the positive electrode active material to the electrolyte, but this kind of oxide generally does not have electronic conductivity and ion conductivity, or the electronic conductivity and ion conductivity are very poor, so it will sacrifice The high capacity and high charge and discharge voltage platform of lithium-ion secondary batteries reduce the energy density of lithium-ion secondary batteries to a certain extent, and this coating method will also increase the overall impedance of lithium-ion secondary batteries and reduce the Kinetic performance of lithium-ion secondary batteries

Method used

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  • Modified cathode active material, preparation method of modified cathode active material and lithium secondary battery
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  • Modified cathode active material, preparation method of modified cathode active material and lithium secondary battery

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preparation example Construction

[0025] Next, illustrate the preparation method of the modified positive electrode active material according to the second aspect of the present invention, which is used to prepare the modified positive electrode active material according to the first aspect of the present invention, comprising the steps of: (1) combining the oxide with the positive electrode active material After mixing and sintering, a positive electrode active material coated with an oxide is obtained, wherein the general formula of the oxide is N x o y , N is selected from one or more of transition metal elements and elements of the third main group, 1 / 4≤y / x≤4; (2) combining the positive electrode active material coated with oxide with the perovskite structure The lanthanum strontium manganese oxide compound is mixed and sintered, so that the lanthanum strontium manganese oxide compound is coated on the surface of the oxide, and the modified positive electrode active material is obtained.

[0026] In the p...

Embodiment 1

[0038] (1) Preparation of modified cathode active materials

[0039] La(NO 3 ) 3 , Sr(NO 3 ) 2 , Mn(NO 3 ) 2 Mix according to the material ratio of 7:3:10, add to deionized water and mix evenly to prepare a nitrate solution with a total concentration of La, Sr, and Mn metal ions of 0.5mol / L. Adding citric acid as a complexing agent, the mass ratio of citric acid and nitrate is 1-2, and then stirring evenly. Add dilute ammonia water to adjust the pH of the solution, and control the pH at about 2.5. Ethylene glycol was added under stirring to carry out solization reaction, and the amount of ethylene glycol was controlled to be the same as that of citric acid, and then the solution was heated to 80° C. for gelation treatment to obtain a wet gel. Dry the wet gel at a constant temperature of 120° C. for 24 hours to dehydrate to prepare a xerogel. Then the obtained xerogel was subjected to self-propagating sintering reaction at 300°C for 1 h to obtain La 0.7 Sr 0.3 MnO 3 ...

Embodiment 2

[0048] Lithium-ion secondary batteries were prepared according to the method of Example 1, the difference being:

[0049] (1) Preparation of modified cathode active materials

[0050] La 0.7 Sr 0.3 MnO 3 The synthesis is the same as in Example 1.

[0051] ZrO 2 and positive active material LiNi 0.5 co 0.25 mn 0.25 o 2 Mixed according to the mass ratio of 0.1:100, and then sintered at 600 ° C for 6 hours to obtain the coated ZrO 2 positive electrode active material; the above material and La 0.7 Sr 0.3 MnO 3 Mix in solid phase at a mass ratio of 100:0.3, sieve, and then perform solid phase sintering at 600° C. to 650° C. for 8 hours to obtain the modified positive electrode active material.

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Abstract

The invention provides a modified cathode active material, a preparation method of the modified cathode active material and a lithium secondary battery, the modified cathode active material comprisesa cathode active substance in the inner core and a coating layer coated on the surface of the cathode active substance. The coating layer is in a double-layer structure and comprises an inner layer coated on the surface of the cathode active substance and an outer layer coated on the surface of the inner layer. The inner layer is chosen from oxides, the general formula is NxOy, N is one or more oftransition metal elements and third main group elements, and y / x is more than or equal to 1 / 4 and less than or equal to 4. The outer layer is chosen from lanthanum manganese strontium oxides having aperovskite structure. The modified cathode active material prolongs the cycle and storage lives of the lithium secondary battery, the polarization of a microcell of a cathode sheet is reduced, the overall resistance value of the lithium secondary battery is reduced, and the dynamic performance of the lithium secondary battery is improved.

Description

technical field [0001] The invention relates to the technical field of batteries, in particular to a modified positive electrode active material, a preparation method thereof, and a lithium secondary battery. Background technique [0002] In order to improve the service life and storage performance of lithium-ion secondary batteries, the usual strategy is to improve the stability of the surface of the positive electrode active material and strengthen the structural stability of the positive electrode active material itself. At present, the commonly used method is to coat the surface of the positive electrode active material with oxides of simple structure (such as TiO 2 , Nb 2 o 5 、Al 2 o 3 , ZrO 2 , Y 2 o 3 , B 2 o 3 etc.), this coating method can reduce the oxidation of the positive electrode active material to the electrolyte, but this type of oxide generally does not have electronic conductivity and ion conductivity, or the electronic conductivity and ion conduc...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/62H01M4/505H01M4/525H01M10/0525
CPCH01M4/366H01M4/505H01M4/525H01M4/624H01M10/0525Y02E60/10
Inventor 梁伟汪龙李奇峰柳娜李鲲阮丁山
Owner CONTEMPORARY AMPEREX TECH CO
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