Modified positive electrode material and preparation method thereof and lithium ion battery

A positive electrode material and modification technology, applied in the field of modified positive electrode materials, its preparation method and lithium ion batteries, can solve the problems of high free lithium on the surface, decreased cycle performance, obvious side effects, etc., achieve simple preparation method and reduce contact range , The effect of improving cycle performance

Inactive Publication Date: 2018-07-24
CONTEMPORARY AMPEREX TECH CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] Positive electrode materials, especially high-nickel positive electrode materials, generally have the problem of excessive free lithium on the surface. Excessively high free lithium will cause the material to easily form jelly during the homogenization process, affecting coating, and eventually lead to loss of reversible capacity and Decrease in cycle performance
[0003] In the prior art, although there are many ways to remove part of the free lithium in the positive electrode material, while removing part of the free lithium, it will more or less adversely affect other properties, such as excessive increase in specific surface area, cycle performance, etc. decline and decrease in specific capacity, etc.
[0004] Commonly used methods mainly include the following: 1) The method of washing with water to reduce the content of free lithium on the surface, although this method can reduce the content of free lithium and improve cycle performance, but the side effects are obvious, and the specific capacity of the material after washing is much lost , the increase in the specific surface increases the contact surface with the electrolyte, which eventually leads to more side reactions
2) Coating is carried out by secondary sintering after solid phase mixing. The disadvantage of this method is that the surface of the positive electrode material cannot be well and uniformly coated, and the effect of performance improvement is limited.
3) Secondary sintering through water phase coating. Although this method can uniformly coat the surface of the material and improve cycle performance, the first charge and discharge efficiency of the positive electrode material drops greatly, and it is not suitable for coating with high nickel materials. cover

Method used

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  • Modified positive electrode material and preparation method thereof and lithium ion battery
  • Modified positive electrode material and preparation method thereof and lithium ion battery
  • Modified positive electrode material and preparation method thereof and lithium ion battery

Examples

Experimental program
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Effect test

Embodiment 1

[0030] Determination of free lithium (LiOH, LiOH, 2 CO 3 ) content, calculate the theoretical amount of phosphite ion needed to completely precipitate free lithium, and convert it into the total amount of phosphorous acid.

[0031] Weigh 3g of phosphorous acid and dissolve it in 800g of ethanol to form a phosphorous acid alcohol phase solution;

[0032] Add 500gLiNi 0.6 co 0.2 mn 0.2 o 2 Material, stirred for 30 minutes to make it evenly dispersed to obtain a slurry;

[0033] Transfer the slurry to an oven and dry at 80°C for 10 hours to obtain a dry powder;

[0034] The dry powder was placed in a muffle furnace under an air atmosphere, heated to 300° C. for 8 hours at a heating rate of 4° C. / min, and fired for 8 hours. After cooling, a modified positive electrode material with a uniform coating layer was obtained. figure 1 is the SEM image of the modified positive electrode material prepared in Example 1. From figure 1 It can be seen that, through the alcohol phase t...

Embodiment 7

[0058] The modified positive electrode material prepared in Example 1 is uniformly mixed with Super P and PVDF binder in NMP solvent at a mass ratio of 90:5:5 to make a slurry with a solid content of 45%, and this slurry is coated with Spread on aluminum foil, dry at 85°C for 5 hours, place the positive pole piece at 105°C for 10 hours in vacuum, and punch it into a circular pole piece with a diameter of 14 mm. The circular pole piece is used as the positive electrode, and Celgard 2400 is used as the separator. With metal lithium sheet as negative electrode, 1M LiPF with EMC:EC:DMC=1:1:1 6 Made into a button battery as an electrolyte.

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Abstract

The invention discloses a preparation method of a modified positive electrode material. The preparation method comprises the following steps of dissolving phosphorous acid into an organic alcohol solution to form a phosphorous acid alcohol phase solution; adding a positive electrode material and performing stirring and uniform dispersing to obtain paste; performing drying on the paste to obtain dried powder; and putting the dried powder into air or oxygen atmosphere to be calcined, and then performing cooling to obtain the modified positive electrode material with a uniform coating layer. Compared with the prior art, by performing positive electrode material modification in the invention, the initial charging-discharging efficiency and specific discharge capacity of the material can be improved effectively, and the cycle performance of the material is improved; and the modified positive electrode material is simple in preparation method, low in production cost and suitable for industrial production. In addition, the invention also discloses the modified positive electrode material and a lithium ion battery adopting the same.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, and more specifically, the invention relates to a modified positive electrode material, a preparation method thereof and a lithium ion battery. Background technique [0002] Positive electrode materials, especially high-nickel positive electrode materials, generally have the problem of excessive free lithium on the surface. Excessively high free lithium will cause the material to easily form jelly during the homogenization process, affecting coating, and eventually lead to loss of reversible capacity and Decreased cycle performance. [0003] In the prior art, although there are many ways to remove part of the free lithium in the positive electrode material, while removing part of the free lithium, it will more or less adversely affect other properties, such as excessive increase in specific surface area, cycle performance, etc. The decline and the reduction of specific capacity, etc. [000...

Claims

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Application Information

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Patent Type & AuthorityApplications(China)
IPC IPC(8): H01M4/36H01M4/525H01M4/505H01M4/485H01M4/62H01M10/0525B82Y30/00
CPCB82Y30/00H01M4/366H01M4/485H01M4/505H01M4/525H01M4/628H01M10/0525Y02E60/10
Inventor倪欢陈玉君况新亮梁建东柳娜汪龙
OwnerCONTEMPORARY AMPEREX TECH CO