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Gradient potential distribution composite electrode, preparation method thereof and power battery

A composite electrode and potential distribution technology, applied in battery electrodes, non-aqueous electrolyte battery electrodes, secondary batteries, etc., can solve problems such as increasing environmental protection requirements, uneven stress distribution, and porosity defects in the second active layer, and improve production. Efficiency and yield, improving uniformity and consistency, avoiding residual porosity defects

Inactive Publication Date: 2021-09-17
KUNSHAN BAOTRON NEW ENERGY TECH CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But in actual application, if it is to prepare the positive sheet that contains multi-layer positive electrode active layer, there are following problems: 1. Before coating the second active layer, if the first active layer is not subjected to rolling pretreatment, then coating When laying the second layer of material, the solvent in the second layer of slurry will quickly penetrate into the first active layer, slowly volatilize and penetrate the second active layer during the subsequent baking process, resulting in residues on the surface of the second active layer A large number of pore defects affect the consistency of the final battery; 2. Before coating the second active layer, if the first active layer is pretreated by rolling, the rolling process will be in the coating area and blank area of ​​​​the current collector. Uneven stress distribution occurs, which leads to serious curling and even belt breakage of the positive electrode sheet in the drying tunnel when coating the second active layer
If the third and fourth layers of coating are also carried out, the problem is even more serious; if it is to prepare a negative electrode sheet containing a multilayer negative electrode active layer, there are the following problems: one, the negative electrode slurry usually adopts water-based slurry, and the water-based slurry Poor adhesion, if the water-based slurry is still used for the second coating, the bottom coating layer will be peeled off from the current collector, resulting in coating failure; if the oil-based slurry is used for coating, it is still inevitable The defect of partial powder falling; 2. The whole process is coated with oily slurry successively, which increases the environmental protection requirements of equipment and environment, as well as the complexity of the process, increases the cost and increases the number of defects

Method used

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  • Gradient potential distribution composite electrode, preparation method thereof and power battery
  • Gradient potential distribution composite electrode, preparation method thereof and power battery
  • Gradient potential distribution composite electrode, preparation method thereof and power battery

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preparation example Construction

[0035] A preparation method of a composite electrode with gradient potential distribution, comprising the following steps:

[0036] Using a multi-layer co-extrusion coating method, a variety of electrode active slurries are simultaneously coated on the collector side to form a multi-layer electrode active layer, and the electrode active slurries are positive electrode active slurries, In the direction of the fluid, the potential gradient of the multi-layer electrode active layer decreases gradually, or the electrode active slurry is a negative electrode active slurry, and the potential gradient of the multi-layer electrode active layer increases gradually along the direction away from the current collector;

[0037] Using the multi-layer co-extrusion coating method, a variety of electrode active slurries are simultaneously coated on the other side of the current collector to form a multi-layer electrode active layer', with the current collector as the axis, two sides The elect...

Embodiment 1

[0078] This embodiment provides a composite positive electrode with gradient potential distribution and a preparation method thereof, the steps are as follows:

[0079] 1) Preparation of the first positive electrode active slurry

[0080] In terms of parts by mass, mix 96 parts of lithium-rich manganese-based solid solution materials, 2 parts of PVDF, 1 part of SP, 1 part of CNT and 43 parts of NMP (note: a total of 143 parts, of which 100 parts are solid materials, and the remaining 43 parts are liquid The solvent will be baked clean), and the first positive electrode active slurry is prepared, the viscosity at 25° C. is 7000-8000 mPa.s, and the solid content is 70%.

[0081] 2) Preparation of the second positive electrode active slurry

[0082] In terms of parts by mass, 96.5 parts of NCM, 1.5 parts of PVDF, 1 part of SP, 1 part of CNT and 41 parts of NMP were mixed to prepare the second positive electrode active slurry. The viscosity at 25°C was 8000-8500mPa.s, and the sol...

Embodiment 2

[0089] This embodiment provides a composite positive electrode with gradient potential distribution and a preparation method thereof, the steps are as follows:

[0090] 1) Preparation of the first positive electrode active slurry

[0091] In parts by mass, 97 parts of NCM, 1 part of PVDF, 1 part of SP, 1 part of CNT and 46 parts of NMP were mixed to prepare the first positive electrode active slurry. The viscosity at 25°C was 7500-8000mPa.s, and the solid content was 68.5%.

[0092] 2) Preparation of the second positive electrode active slurry

[0093] In parts by mass, 95 parts of LFP, 2.5 parts of PVDF, 1.5 parts of SP, 1 part of CNT and 125 parts of NMP were mixed to prepare the second positive electrode active slurry. The viscosity at 25°C was 8900-9200mPa.s, and the solid content was 44.4%.

[0094] 3) Preparation of composite positive electrode

[0095] Add the first positive electrode active slurry and the second positive electrode active slurry into the coating head ...

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Abstract

The invention relates to the technical field of power batteries, in particular to a gradient potential distribution composite electrode, a preparation method of the composite electrode and a power battery. The preparation method comprises the following steps that a multi-layer co-extrusion coating method is adopted, one side of a current collector is coated with multiple kinds of electrode active slurry at the same time, multiple electrode active layers are formed, and the potential gradient of the multiple electrode active layers is gradually increased or gradually decreased in the direction away from the current collector; by adopting the multi-layer coextrusion coating method, the other side of the current collector is coated with multiple electrode active slurry at the same time to form multiple electrode active layers, and the electrode active layers on the two sides are symmetrically distributed with the current collector as the axis, wherein the number of layers is not less than 2. According to the invention, various defects caused by preparation of multiple electrode active layers by a layer-by-layer coating method are solved, the interface performance of each potential electrode active layer in the composite electrode with gradient potential distribution can be improved, and the safety of the battery under the condition of internal short circuit thermal runaway is further improved.

Description

technical field [0001] The invention relates to the technical field of power batteries, in particular to a composite electrode with gradient potential distribution, a preparation method thereof and a power battery. Background technique [0002] The safety of power batteries is a common problem faced by the entire battery industry at present. The frequent fire accidents of new energy vehicles in recent years have raised the intrinsic safety of batteries to the height that determines the fate of the entire industry. The thermal runaway of lithium-ion batteries is the core cause of power battery safety accidents. How to improve the safety of power batteries from the cell level is imminent. [0003] The battery cell includes positive and negative electrodes. How to design and prepare positive and negative electrode materials to improve the safety of the battery in the case of internal short-circuit thermal runaway is a key research topic in the industry. [0004] In addition, w...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/139H01M4/13H01M4/36H01M10/0525
CPCH01M4/13H01M4/139H01M10/0525H01M4/366Y02E60/10
Inventor 刘永飞梁世硕张国军
Owner KUNSHAN BAOTRON NEW ENERGY TECH CO LTD
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