Positive plate and lithium ion battery comprising same

A positive electrode, positive electrode technology, applied in the direction of positive electrode, battery electrode, secondary battery, etc., can solve problems such as fire failure, and achieve the effect of reducing contact probability, improving safety, and reducing short circuit probability.

Inactive Publication Date: 2021-04-02
ZHUHAI COSMX BATTERY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The present invention provides a positive electrode sheet and a lithium ion battery including the positive electrode sheet. The use of the positive electrode sheet can solve the problems of lithium ion battery fire and failure in the case of mechanical abuse, and improve the safety performance of the lithium ion battery. At the same time, the The cycle performance of lithium-ion batteries is not affected, which is equivalent to that of existing lithium-ion batteries, that is, the safety performance of lithium-ion batteries is significantly improved while maintaining the cycle performance of lithium-ion batteries

Method used

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  • Positive plate and lithium ion battery comprising same
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  • Positive plate and lithium ion battery comprising same

Examples

Experimental program
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preparation example Construction

[0077] The present invention also provides a method for preparing the above positive electrode sheet, the method comprising the following steps:

[0078]1) preparing the slurry forming the first coating and the slurry forming the second coating respectively;

[0079] 2) Coating the slurry for forming the first coating layer and the slurry for forming the second coating layer on both surfaces of the positive electrode current collector to prepare the positive electrode sheet.

[0080] According to the present invention, in step 2), the coating is double layer coating, gravure coating, extrusion coating, transfer coating.

[0081] Exemplarily, step 2) specifically includes the following steps:

[0082] Coating the slurry for forming the first coating on the surface of the positive electrode collector to form the first coating, and coating the slurry for forming the second coating on the surface of the first coating to form the second coating to obtain a positive electrode sheet...

Embodiment 1

[0105] The first step: prepare the first coating slurry, mix 40wt% lithium iron phosphate (LFP), 45wt% modified PVDF, 15wt% carbon black, add NMP, and prepare the slurry by stirring.

[0106] The second step: preparing the second coating slurry, mixing 97wt% lithium cobaltate, 1wt% conductive carbon black, 0.8wt% carbon nanotubes, 1.2wt% PVDF1, adding NMP, and stirring to prepare a slurry.

[0107] The third step: preparing negative electrode slurry, mixing 96wt% artificial graphite, 1wt% conductive carbon black, 1.5wt% SBR and 1.5wt% CMC, adding deionized water, and stirring to prepare a slurry.

[0108] Step 4: Preparation of the positive electrode sheet. Use the extrusion coating process to coat the first coating slurry in step 1 on the surface of the positive electrode current collector to form a first coating with a thickness of 5 μm, and apply the second coating in step 2 The slurry was coated to form a second coating with a thickness of 40 μm on the surface of the first...

Embodiment 2

[0114] The first step: prepare the first coating slurry, mix 93wt% LFP, 5wt% modified PVDF, 2wt% carbon black, add NMP, and prepare the slurry by stirring.

[0115] The second step to the sixth step are the same as in Example 1.

[0116] The adhesion test was carried out on the prepared lithium-ion battery, and the surface state of the pole piece after the peeling test was as follows: Figure 4 , Figure 5 and Image 6 As shown, the particles of the coating part were peeled off from the positive electrode sheet, and Co, O, and P elements were detected on the surface of the peeled electrode sheet, indicating that the bonding force between the first coating and the current collector is greater than the bonding force between the coating particles. The average cohesive force is 45.78N / m. At this time, the first coating of the positive electrode sheet is not peeled off from the current collector, indicating that the cohesive force between the first coating and the current collect...

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Abstract

The invention provides a positive plate and a lithium ion battery comprising the positive plate; the positive plate comprises a positive current collector and a positive coating, the positive coatingcomprises a first coating and a second coating, the surface of the positive current collector is coated with the first coating, and the surface of the first coating is coated with the second coating;the binding power between the first coating and the positive electrode current collector is greater than the binding power between the first coating and the second coating, and/or the binding power between the first coating and the positive electrode current collector is greater than the binding power between positive electrode active material particles of the second coating, and after the positive coating of the positive plate is stripped, the total mass of the residual positive coating on the positive electrode current collector accounts for more than 10% of the total mass of the positive coating on the positive electrode current collector before stripping, so that the obtained lithium ion battery has good safety performance, and the probability of fire failure of the battery is greatlyreduced when mechanical abuse (needling and heavy impact) occurs.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a positive electrode sheet and a lithium ion battery including the positive electrode sheet. Background technique [0002] Lithium-ion batteries are widely used in smartphones, laptops, Bluetooth, wearable devices and other fields due to their advantages such as high platform voltage, high energy density, no memory effect, and long life. However, in some extreme cases, such as when the lithium-ion battery is subjected to mechanical damage (needle puncture, heavy impact, etc.), an internal short circuit will occur, and a lithium-ion battery with an internal short circuit will emit a large amount of heat in a short period of time, causing the battery Failure to catch fire has a great potential safety hazard. [0003] Studies have found that when an internal short circuit occurs in a lithium-ion battery, there will be multiple short-circuit modes, among wh...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/131H01M4/1391H01M4/36H01M4/62H01M10/0525
CPCH01M4/131H01M4/1391H01M4/366H01M4/623H01M10/0525H01M2004/028Y02E60/10
Inventor 张健彭冲李俊义徐延铭
Owner ZHUHAI COSMX BATTERY CO LTD
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