CN112002873B - Pole piece with high bending strength of current collector - Google Patents

Pole piece with high bending strength of current collector Download PDF

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Publication number
CN112002873B
CN112002873B CN201910446327.4A CN201910446327A CN112002873B CN 112002873 B CN112002873 B CN 112002873B CN 201910446327 A CN201910446327 A CN 201910446327A CN 112002873 B CN112002873 B CN 112002873B
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China
Prior art keywords
current collector
pole piece
conductive foil
bending strength
high bending
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CN201910446327.4A
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Chinese (zh)
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CN112002873A (en
Inventor
谭歌
韩笑
李凡群
夏塞塞
陈阳
张伟
张建勇
万华峰
王海伦
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Wanxiang A123 Systems Asia Co Ltd
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Wanxiang A123 Systems Asia Co Ltd
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Priority to CN201910446327.4A priority Critical patent/CN112002873B/en
Publication of CN112002873A publication Critical patent/CN112002873A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H01M4/72—Grids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H01M4/72—Grids
    • H01M4/74—Meshes or woven material; Expanded metal
    • H01M4/745—Expanded metal
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention relates to the technical field of batteries, and aims to solve the problems that a current collector is bent towards one side and is bent and intensified after punching and baking in the prior art under the action of rolling stress. According to the invention, the current collector is prevented from bending to one side in the cell lamination process through the reinforcing structure, so that the problems of collision between the current collector and a welding seat and leakage welding of the current collector in the welding process can be effectively solved, and the low capacity and safety risk of the battery caused by leakage welding are avoided.

Description

Pole piece with high bending strength of current collector
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a pole piece with a high bending strength of a current collector.
Background
The pole piece is a small unit structure which is composed of active substances and conductive foil and has the function of lithium ion insertion and extraction, wherein the active substances are distributed on two sides of the conductive foil. The current collector refers to a metal foil which is connected with the pole piece and can conduct the current inside the battery. The current collector of the existing lithium ion battery pole piece is composed of flat metal foils, a pole piece with the metal foil current collector is formed after pole rolls are rolled and punched, and the surface of the formed current collector structure is smooth and flat. The current collector is bent to one side due to the action of rolling stress in the pole piece rolling process, and the current collector is bent to one side and aggravated after the pole piece is stamped. This kind of bending can be more serious in the pole piece toasts the in-process, and the bend angle leads to at electric core lamination in-process, and the mass flow body is crooked to electric core one side, and the mass flow body appears in the phenomenon that the welding seat collided and the mass flow body leaks to weld in welding process. Resulting in low battery capacity and also a safety risk.
For example, a "current collector coating and electrode sheet" disclosed in chinese patent literature, whose publication number CN 207558937U includes: the protective layer is formed on the surface of the current collector, the active material is formed on the protective layer, the protective layer comprises expansion microspheres and a conductive agent, the active material layer comprises the active material, and the expansion microspheres expand when the temperature of the protective layer is greater than or equal to a temperature threshold value, so that the current collector is disconnected from the active material layer. According to the technical scheme, on the premise that the energy density of the unit volume of the battery is not reduced and the production cost of the battery is not increased, the battery is ensured not to continue to be charged and discharged when the temperature is too high, and the safety of the battery is improved. But does not solve the problem of the current collector that the bending is aggravated after punching and baking.
Disclosure of Invention
The invention provides a pole piece with high bending strength of a current collector, aiming at overcoming the problems that the current collector is bent towards one side under the action of rolling stress and the bending is aggravated after punching and baking.
In order to achieve the purpose, the invention adopts the following technical scheme:
the utility model provides a mass flow body pole piece that bending strength is high, includes conducting foil and the active material coating of coating in the conducting foil both sides, and conducting foil includes first district and second district, and the second district is connected in the first district, and the first district is equipped with the active material coating, is equipped with additional strengthening in the second district, and additional strengthening meets with the first district, additional strengthening locates the conducting foil both sides. The problem of the mass flow body to the one side bending that rolling stress leads to can be solved to additional strengthening, can solve simultaneously towards the piece with toast the problem of the crooked aggravation of the mass flow body after, avoid electric core lamination in-process, the mass flow body is to the one side bending, effectively solves the problem of the mass flow body and the collision of weld holder and the mass flow body hourglass welding in welding process. The low capacity of the battery caused by welding leakage is avoided, and the existing safety risk is avoided.
Preferably, the reinforcing structure is a net structure consisting of circular bulges or polygonal bulges formed by continuously and deeply printing on the surface of the conductive foil. The structure has stability, and the stress can be dispersed to achieve the effect of bending resistance.
Preferably, when the net-like structure is composed of circular protrusions, the surfaces of the adjacent circular protrusions are arranged in contact with each other, and grooves are formed between the adjacent circular protrusions. The structure can better disperse stress to each bump and prevent the conductive foil from bending.
Preferably, the diameter of the circular bulge is 1-3 mm. The diameter should be compatible with the width of the conductive foil and should not be too large to exceed the width of the conductive foil.
Preferably, when the mesh-like structure is composed of polygonal protrusions, edges of adjacent polygonal protrusions are arranged in a connection manner, and grooves are formed between the adjacent polygonal protrusions. The structure can better disperse stress to each bump and prevent the conductive foil from bending.
Preferably, the side length of the polygonal bulge is 2-5 mm. The side length should be adapted to the width of the conductive foil so that the network structure is more distributed on the conductive foil.
Preferably, the conductive foil is a metal foil having a thickness of 6 to 30 μm and a width of 10 to 20 mm. The thickness of the conductive foil should be greater than the thickness of the two layers of the reinforcing structures, and a blank conductive foil portion is left between the two layers of the reinforcing structures, and the width of the conductive foil portion should be capable of accommodating a certain number of reinforcing structures of different shapes.
Preferably, the composition ratio of the active material coating is as follows: 33.10 percent of active substance, 3.03 percent of binder, 0.87 percent of conductive agent and 63.00 percent of solvent. The active material coating layer in the proportion can provide static conductivity and collect micro-current of the active material, thereby greatly reducing contact resistance between the positive/negative electrode material and current collection.
Preferably, the active substance coating is applied to one side of 10.0 +/-0.5 mg/cm2The coating amount of (2) is uniformly coated on both sides of the conductive foil. The active material coating with proper thickness can avoid the reduction of the cycle performance and the rate performance of the battery caused by the difficulty in the infiltration of the electrolyte and the maintenance of the electrolyte.
Preferably, the rolling design compaction density of the pole piece is 1.6g/cm3. The pole piece is compressed in volume by rolling, so that the impedance can be reduced, and the multiplying power performance of the battery is improved.
Therefore, the invention has the following beneficial effects: (1) the problem of bending of a pole piece current collector is avoided; (2) the problem of leakage welding of the current collector in the welding process is avoided; (3) the problem of low capacity of the battery is avoided, and the qualification rate is improved.
Drawings
Fig. 1 is a schematic structural view of the present invention.
FIG. 2 is a schematic structural view of the A-A section of the present invention.
Fig. 3 is a partial enlarged view at B in fig. 2.
Fig. 4 is a schematic structural diagram of an embodiment of the present invention.
In the figure: 1. active material coating, 2, conductive foil, 3, reinforcing structure, 31, triangular protrusion, 32, triangular groove.
Detailed Description
The invention is further described with reference to the following detailed description and accompanying drawings.
As shown in fig. 1, a pole piece with a high bending strength of a current collector comprises a conductive foil and active material coatings 1 coated on two sides of the conductive foil 2, wherein the conductive foil comprises a first area and a second area, the first area is connected with the second area, the first area is provided with the active material coatings, the second area is provided with a reinforcing structure 3, the reinforcing structure is connected with the first area, and the reinforcing structure is arranged on two sides of the conductive foil. The effect of rolling stress can lead to conducting foil to one side bending at the in-process that the pole piece rolled, can make crooked aggravation behind the pole piece towards the piece simultaneously, and this additional strengthening dispersibility rolling stress makes conducting foil bear the stress and reduces, avoids crooked problem.
As shown in figure 2, the reinforcing structure is a net structure formed by triangular bulges formed by continuously and deeply printing on two sides of the conductive foil, the side length is 2-5 mm, as shown in figure 3, the reinforcing structure is distributed on two sides of the conductive foil, wherein the depth of one side of the conductive foil is 3-10 mu m, the length of the one side of the conductive foil is 3-6 mm, and a blank conductive foil without the reinforcing structure is left between the two layers of the reinforcing structures.
Further, in order to enhance the strength of the reinforcing structure and enhance the stress dispersion, as shown in fig. 4, adjacent triangular protrusions 31 in the net structure are connected at edges, so that the connected triangular protrusions form triangular grooves 32, and are continuously distributed on the conductive foil.
As other embodiments of the present invention, the printing of the net structure may also be other polygonal protrusions or circular protrusions. When the printing of the net-shaped structure is circular bulges, the surfaces of the adjacent circular bulges are connected to enhance the strength of the structure and enhance the stress dispersion, so that grooves are formed between the circular bulges, and the diameter of each circular bulge is 1-3 mm. When the printing of the net-shaped structure is convex in other polygons, the convex edges of the adjacent polygons are connected with each other, a groove is formed between the adjacent polygons, and the side length of each polygon is 2-5 mm.
The preparation scheme of the bending-resistant pole piece is as follows:
the method comprises the following steps: the metal foil with the foil thickness of 6-30 mu m and the width of 10-20 mm is used as the conductive foil, and the reinforcing structure is arranged on the conductive foil.
Step two: the active material coating composition is prepared into slurry according to the proportion of 33.10 percent of active material content, 3.03 percent of binder content, 0.87 percent of conductive agent content and 63.00 percent of solvent content.
Step three: the active substance slurry is mixed according to a single surface of 10.0 +/-0.5 mg/cm2Is uniformly coated on both sides of the conductive foil, whereinThe areas provided with the reinforcing structure are not coated with the active material slurry.
Step four: rolling to manufacture pole pieces with the rolling design compaction density of 1.6g/cm3. And finally finishing the manufacture of the pole piece.
The above-mentioned embodiments are merely illustrative of the technical concept and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the content of the present invention and implement the present invention, and not to limit the scope of the present invention, and all equivalent changes, modifications or improvements made according to the spirit of the present invention should be covered by the scope of the present invention.

Claims (7)

1. A pole piece with a high bending strength of a current collector is characterized by comprising a conductive foil and active substance coatings (1) coated on two sides of the conductive foil (2), wherein the conductive foil comprises a first area and a second area, the first area is connected with the second area, the first area is provided with the active substance coatings, the second area is provided with a reinforcing structure (3), the reinforcing structure is connected with the first area, and the reinforcing structure is arranged on two sides of the conductive foil; the reinforcing structure is a net structure consisting of circular bulges or polygonal bulges formed by continuously and deeply printing on the surface of the conductive foil; the thickness of the conductive foil is larger than that of the two layers of the reinforcing structures; when the reticular structure consists of the circular bulges, the surfaces of the adjacent circular bulges are connected and arranged, and a groove is formed between the adjacent circular bulges; when the net-shaped structure is composed of the polygonal bulges, the edges of the adjacent polygonal bulges are connected and arranged, and a groove is formed between the adjacent polygonal bulges.
2. The pole piece with the current collector having high bending strength as claimed in claim 1, wherein the diameter of the circular protrusion is 1-3 mm.
3. The pole piece with the current collector having high bending strength as claimed in claim 1, wherein the side length of the polygonal protrusion is 2-5 mm.
4. The pole piece with the current collector having high bending strength as claimed in claim 1, wherein the conductive foil is a metal foil with a thickness of 6 μm to 30 μm and a width of 10 mm to 20 mm.
5. The pole piece with the current collector having high bending strength as claimed in claim 1, wherein the active material coating comprises the following components in percentage by weight: 33.10 percent of active substance, 3.03 percent of binder, 0.87 percent of conductive agent and 63.00 percent of solvent.
6. The pole piece with high bending strength of the current collector as claimed in claim 1 or 5, wherein the active material coating is 10.0 ± 0.5mg/cm on one side2The coating amount of (2) is uniformly coated on both sides of the conductive foil.
7. The pole piece with high bending strength of the current collector as claimed in claim 1, wherein the roll design compaction density of the pole piece is 1.6g/cm3。
CN201910446327.4A 2019-05-27 2019-05-27 Pole piece with high bending strength of current collector Active CN112002873B (en)

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CN112002873B true CN112002873B (en) 2022-03-18

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Publication number Priority date Publication date Assignee Title
CN115036456B (en) * 2022-06-17 2023-08-15 欣旺达电动汽车电池有限公司 Electrode plate and battery core

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JP2013095972A (en) * 2011-11-02 2013-05-20 Furukawa Electric Co Ltd:The Electrolytic copper foil, and wiring board and battery using electrolytic copper foil
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