CN219534833U

CN219534833U - Structure for protecting lug die cutting by using adhesive tape

Info

Publication number: CN219534833U
Application number: CN202320286963.7U
Authority: CN
Inventors: 梁永胜
Original assignee: Gaoqu Digital Technology Ningde Co ltd
Current assignee: Gaoqu Digital Technology Ningde Co ltd
Priority date: 2023-02-22
Filing date: 2023-02-22
Publication date: 2023-08-15
Anticipated expiration: 2033-02-22

Abstract

The utility model relates to the technical field of lithium battery manufacturing, in particular to a structure for protecting tab die cutting by using an adhesive tape, which comprises an aluminum foil, wherein a main material coating is arranged on the surface of the aluminum foil, a composite adhesive tape layer is arranged on the upper side edge of the main material coating, and a composite material main body is formed after rolling; the composite adhesive tape layer consists of a PP film and a PP hot melting layer; a PP film is arranged outside the PP hot melting layer; cutting an upper region B and a lower region C at two sides of the right end of the composite material main body, wherein a residual part between the upper region B and the lower region C forms a tab; overlapping and covering parts of the composite material main body and the electrode lugs to form a covering area; coating a PP film and a PP hot melting layer on an aluminum foil to form a composite material, so as to replace the traditional ceramic slurry; the adhesive tape is adhered to the aluminum foil by a hot pressing method to form a pole piece protection structure; the method can effectively prevent burrs generated by die cutting from piercing the diaphragm, effectively avoid internal short circuit, and improve the reliability and safety of the lithium battery.

Description

Structure for protecting lug die cutting by using adhesive tape

Technical Field

The utility model relates to the technical field of lithium battery manufacturing, in particular to a die-cut structure for protecting a tab by using an adhesive tape.

Background

Fig. 1 is a schematic side view of a positive electrode plate with a certain type of battery core lithium iron phosphate as a main material. Wherein the dashed line portion 4a is the die cut location. The ceramic paste height and tab height may vary depending on the design. Description of the principle of using ceramic slurry: at present, the electrode lug die cutting is protected by using ceramic slurry. This is because burrs may be generated when the tab is die-cut, either by a cutter or by a laser. Burrs are typically on the order of micrometers (μm), and experimental data indicate that typical burrs are on the order of 4-8 μm.

The burrs are difficult to avoid and cannot be detected by traditional optical vision. The burrs possibly pierce the diaphragm, so that internal short circuit between the anode and the cathode is caused, and the quality and safety of the product are affected. To solve this problem, ceramic slurries are used by various mainstream manufacturers. The die-cut part protected by the ceramic slurry still generates burrs during die-cutting, but the burrs are covered with the rolled ceramic slurry, so that the thickness is large, and the diaphragm is difficult to pierce. Therefore, the safety of the battery cell is improved to a greater extent by coating the ceramic slurry on the pole piece.

Disclosure of Invention

The utility model aims to overcome the defects and shortcomings of the prior art and provides a structure for protecting tab die cutting by using an adhesive tape.

The utility model relates to a die-cut structure for protecting a tab by using an adhesive tape, which comprises an aluminum foil, wherein a main material coating is arranged on the surface of the aluminum foil, a composite adhesive tape layer is arranged on the upper edge of the main material coating, and a composite material main body is formed after rolling; the composite adhesive tape layer consists of a PP film and a PP hot melting layer; a PP film is arranged outside the PP hot melting layer; cutting an upper region B and a lower region C at two sides of the right end of the composite material main body, wherein a residual part between the upper region B and the lower region C forms a tab; and the composite material main body and the overlapped covering part of the tab form a covering area.

Further, the thickness of the aluminum foil was 12 μm.

Further, the thickness of the main material coating is 10-15 mu m.

Further, the PP film had a thickness of 6 μm and a width of 8mm.

Further, the PP hot melt layer had a thickness of 4 μm and a width of 8mm.

After the structure is adopted, the utility model has the beneficial effects that: the utility model relates to a structure for protecting a tab die-cutting by using an adhesive tape, which adopts a mode that a PP film and a PP hot melting layer are coated on an aluminum foil to form a composite material to replace the traditional ceramic slurry; the adhesive tape is adhered to the aluminum foil by a hot pressing method to form a pole piece protection structure; the lithium battery can effectively prevent burrs generated by die cutting from penetrating through the diaphragm, and effectively avoid internal short circuit, so that the reliability and safety of the lithium battery are improved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the utility model and are incorporated in and constitute a part of this specification, illustrate and together with the description serve to explain the utility model, if necessary:

FIG. 1 is a schematic side view of a positive electrode sheet of a lithium battery of the present utility model;

FIG. 2 is a schematic side elevational view of one embodiment of the present utility model;

FIG. 3 is a schematic plan view of a structure embodying the present utility model;

FIG. 4 is a schematic illustration of a die cut top side structure of an embodiment of the present utility model;

FIG. 5 is a schematic side elevational view of another embodiment of the present utility model;

FIG. 6 is a schematic top view of another embodiment of the present utility model;

fig. 7 is a schematic illustration of a die cut top view of another embodiment of the present utility model.

Reference numerals illustrate:

a main material coating layer-1; aluminum foil-2; PP film-3; PP hot melt layer-4; dotted line a-5; an upper region B-6; a lower region C-7; a tab-8; coverage area-9.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments of the present utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

In the description of the present utility model, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

As shown in fig. 2-4, the structure of die cutting using adhesive tape to protect the tab according to this embodiment includes an aluminum foil 2, wherein a main material coating 1 is provided on the surface of the aluminum foil 2, a composite adhesive tape layer is provided on the upper side edge of the main material coating 1, and a composite material main body is formed after rolling; the composite adhesive tape layer consists of a PP film 3 and a PP hot melting layer 4; a PP film 3 is arranged on the outer side of the PP hot melting layer 4;

cutting an upper region B6 and a lower region C7 at two sides of the right end of the composite material main body, and forming a tab 8 at a remained part between the upper region B and the lower region C; the overlapping cover portions of the composite body and the tabs 8 form a cover region 9.

Further, the thickness of the aluminum foil was 12 μm.

Further, the thickness of the main material coating is 10-15 mu m.

Further, the PP film had a thickness of 6 μm and a width of 8mm.

Further, the PP hot melt layer had a thickness of 4 μm and a width of 8mm.

The working principle of the utility model is as follows:

fig. 1 is a side view of a positive electrode tab of a lithium battery of a conventional mainstream product. The aluminum foil 1a is provided with a rolled lithium iron phosphate coating. The specific preparation process is as follows:

(1) A slurry of a main material of the positive electrode material (e.g., a ternary material or a lithium iron phosphate material) is prepared using a stirring device, and the binder is typically PVDF. Meanwhile, stirring equipment is used for manufacturing the anode plate protection slurry, which is also called ceramic slurry 3a. The ceramic slurry 3a has alumina (Al as a main component ₂ O ₃ ) Or boehmite (gamma-AlOOH), and the binder is PVDF.

(2) A positive electrode material 2a (lithium iron phosphate coating) was coated on the aluminum foil 1 a. At the same time of the main material coating, the ceramic slurry 3a coating with the thickness of 8-10mm is carried out on the two sides of the main material coating, and the thickness of the ceramic slurry 3a coating is consistent with the thickness of the main material coating.

(3) And (3) after the surface A is coated, the aluminum foil is put into an oven, baking and heating are carried out on the coated aluminum foil, and the solvent is evaporated, so that the main material and the ceramic slurry are firmly attached to the aluminum foil under the bonding action of PVDF.

(4) The 2-3 steps were then repeated for B-side coating while ensuring A, B side coating alignment.

(5) The positive pole piece is subjected to cold pressing (also called rolling), so that the density of the pole piece coating material is improved under pressure, and the energy density is improved.

(6) And cutting the positive electrode plate. And (7) controlling the moisture of the positive pole piece. And (8) cutting the cutter or the laser tab. Thus, the positive pole piece with the pole lug is manufactured.

The problems existing in the prior art are solved. The present design solves the above problems by adopting the following two modes, which are specifically described as follows:

first embodiment: the design is aimed at a 12 mu m PP (polypropylene) composite adhesive tape, which is adhered to an aluminum foil by a hot pressing method to form a pole piece protection structure. This structure can prevent effectively that the burr that the cross cutting produced from penetrating through the diaphragm, effectively avoids the internal short circuit to improve the reliability and the security of lithium cell, this design structure can directly replace ceramic thick liquids.

FIG. 1 is a side view (cut surface) of the structure of the design, wherein the coating thickness of the main material of the positive electrode is 10-15 mu m, the thickness of the aluminum foil is 12 mu m, the height of the tab is 25mm, and the thickness is different variable values according to the cell design. The width of the compound adhesive tape is 8mm, the thickness of the adhesive tape is 12 mu m before the adhesive tape is attached, and 10 mu m after the adhesive tape is hot-pressed and attached. The dashed line A5 is the laser cutting position. In the design, the die-cut composite material main body is compounded with the 8mm adhesive tape through hot pressing.

Fig. 2-4 are block diagrams of the present design in which cutting by laser is performed to form tabs. The specification of the pole piece protection structure is as follows:

(1) The thickness of the PP composite adhesive tape is 12 mu m, wherein the PP film is 6 mu m, the hot-melt layer is 6 mu m, the thickness of the hot-melt layer after lamination is 4 mu m, and the total thickness of the PP composite adhesive tape after hot-melt lamination is 10 mu m. The thickness can meet the requirements of the coating thickness of the positive electrode of the lithium iron phosphate and the ternary material.

(2) The PP composite tape had a width of 8mm, and the reason for this width value setting was stated as follows: a. the adhesive tape is easy to produce. b. The adhesive tape has sufficient adhesive strength. c. Allowing for some deviation in the fit.

In practice, the protection requirement of the pole piece protection area is 2mm enough, so long as the knife edge part of the die cutting can be covered. In the future, with the improvement of the adhesive tape production process, when the adhesive tape attaching strength and attaching precision can meet the requirements, the adhesive tape with the width of 2mm can be adopted, so that the material can be greatly saved, but the current process does not support.

(3) The PP composite adhesive tape is not necessarily clung to the positive electrode main material. The core of the structure is that: the PP composite adhesive tape covers the position of the die cutting opening.

In particular, in the process of producing lithium batteries, the adhesive tape may be bonded to form the structure prior to die cutting of the tab. When the tab is die-cut, a burr-adhesive tape complex (the function of the structure) is formed on burrs formed by the aluminum foil, so that the lithium battery diaphragm is basically not pierced, the positive electrode plate is protected, internal short circuit is prevented, and the reliability and safety of the battery are improved. The structure can completely replace the ceramic slurry technology used at present.

The PP composite adhesive tape is required to be provided with the following structure: a. good insulation and high voltage resistance. b. The bonding strength is high, and the PP film material can be firmly adhered to the surface of the aluminum foil. c. And is resistant to electrolyte corrosion. The bonding strength can be maintained under the environment of electrolyte soaking. d. After lamination, the thickness of the adhesive tape cannot be higher than the coating thickness of the positive electrode main material. Otherwise pole piece bulging easily occurs when the battery cells are wound or laminated.

Specific embodiment II: the application is further described as follows: and a narrower adhesive tape is used, and the adhesive tape is attached after the die cutting of the electrode lugs, so that a protective layer is formed to protect the positive electrode lug and avoid burrs from penetrating through the diaphragm.

As shown in fig. 5-7, is a side view of the above structure. The aluminum foil of 12 μm is rolled with a primary coating of 10-15 μm. The difference from the first application mode is that the application places the PP composite tape after die cutting.

The advantages of the above structure are: the cut section of the lug die cutting can be completely wrapped by the PP composite adhesive tape, and the burrs perpendicular to the surface of the pole piece or parallel to the surface of the pole piece can be covered, so that the safety of the pole piece is better ensured. The pole piece protection structure has the following application specifications:

(1) The thickness of the PP composite adhesive tape is 12 mu m, wherein the PP film is 6 mu m, the hot-melt layer is 6 mu m, and the thickness of the hot-melt layer after lamination is 4 mu m. The total thickness after the hot melt lamination was 10. Mu.m. The thickness can meet the requirements of the coating thickness of the positive electrode of the lithium iron phosphate and the ternary material.

(2) The width of the PP composite adhesive tape is 3mm (1 mm is left on the aluminum foil, 2mm is used for bonding the AB surface adhesive tapes mutually), the incision part of die cutting can be covered, and the adhesive tapes on the two sides of the AB surface can be bonded.

(3) The core of this design structure is: (3.1) PP composite tape covers the die-cut opening position. (3.2) the PP composite tape AB surface is aligned and bonded to each other to completely cover the die cutter port end face.

In summary, the key protection innovation points are as follows: the structure of the pole piece is protected by using the PP composite adhesive tape to be overlapped at the position of the notch of the pole lug, and the important point is that the position of the adhesive tape covers the notch. The two embodiments described above differ in the position of the covering of the two cuts, and the structure itself is identical (whether the width of the tape is a few millimeters).

The two different applications in this design do not represent all the possibilities of using this protective structure, since the lamination of the PP composite tape can be added after the pole piece coating is completed, before winding (lamination) and the tape width can be the same from 2mm to tens of millimeters.

The above embodiments are only for illustrating the technical solution of the present utility model, and are not limiting; although the utility model has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present utility model.

Claims

1. Use sticky tape protection utmost point ear cross cutting structure, its characterized in that: the aluminum foil comprises an aluminum foil (2), wherein a main material coating (1) is arranged on the surface of the aluminum foil (2), a composite adhesive tape layer is arranged on the upper side edge of the main material coating (1), and a composite material main body is formed after rolling; the composite adhesive tape layer consists of a PP film (3) and a PP hot melting layer (4); a PP film (3) is arranged on the outer side of the PP hot melting layer (4); the two sides of the right end of the composite material main body are cut into an upper area B (6) and a lower area C (7), and a residual part between the upper area B (6) and the lower area C (7) forms a tab (8); and the overlapping covering part of the composite material main body and the tab (8) forms a covering area (9).

2. The structure of claim 1, wherein the die-cut tab is protected by adhesive tape, and the structure is characterized in that: the thickness of the aluminum foil (2) is 12 μm.

3. The structure of claim 1, wherein the die-cut tab is protected by adhesive tape, and the structure is characterized in that: the thickness of the main material coating (1) is 10-15 mu m.

4. The structure of claim 1, wherein the die-cut tab is protected by adhesive tape, and the structure is characterized in that: the PP film (3) had a thickness of 6 μm and a width of 8mm.

5. The structure of claim 1, wherein the die-cut tab is protected by adhesive tape, and the structure is characterized in that: the thickness of the PP hot melt layer (4) is 4 mu m, and the width is 8mm.