Inner protective film and battery cell
By designing an internal protective film that is heat-deformed, the problems of insufficient electrolyte infiltration at the bottom of the lithium battery cell pack and the powder-loss of the electrode sheet corrode the aluminum shell are solved, and the electrolyte filling and insulation effect is achieved, extending the service life of the battery cell.
Patent Information
- Application Number
- CN202421756608.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-23
- Publication Date
- 2025-05-30
- Estimated Expiration
- 2034-07-23
AI Technical Summary
During the lithium battery manufacturing process, the electrolyte is insufficient infiltrated at the bottom of the core bag, resulting in a shortening of battery life and corrosion of the electrode sheet and the aluminum shell.
An inner protective film is designed to deform by heat and closely fit on the inside of the shell, isolate the direct contact between the core bag and the shell, and ensure that the electrolyte fills the outside of the core bag.
It effectively avoids contact between the electrolyte and the shell, reduces the waste of the electrolyte, extends the service life of the battery cell, and realizes the insulation between the internal charged body and the shell.
Smart Images
Figure CN222927623U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of batteries, in particular to an inner protective film and a battery core. Background Art
[0002] In the manufacturing process of lithium batteries, electrolyte is used as a channel for ion transmission in the battery. The electrolyte plays a role in conducting ions between the positive and negative electrode separators. After long-term storage and use, the electrolyte gradually becomes less due to inevitable side reactions, which shortens the life of the battery. Therefore, electrolyte plays a very important role in battery manufacturing.
[0003] During the manufacturing process, excess electrolyte often fills the empty space inside the battery cell, especially at the bottom of the battery cell. On the one hand, the insulating film wrapped around the core package hinders the entry of the bottom electrolyte to a certain extent, resulting in insufficient infiltration of the core package in the later stage; on the other hand, the powder of the electrode falls off and mixes with the bottom electrolyte, which is easy to corrode the aluminum shell over time.
[0004] Therefore, it is urgent to design a new inner protective film and battery cell to improve the above problems. Utility Model Content
[0005] The utility model aims to provide an inner protective film and a battery cell to solve the technical problem that the insulating film blocks the bottom electrolyte from entering the core package, resulting in insufficient infiltration in the later stage, the pole piece powder falling off and mixing into the bottom electrolyte, and the aluminum shell is easily corroded over time.
[0006] To achieve this purpose, the utility model adopts the following technical solutions:
[0007] An inner protective film, wherein the inner protective film is coated on the outside of the core package, the inner protective film and the core package are arranged in a shell, the inner protective film is used to isolate the core package from direct contact with the shell, and the inner protective film is deformed by heat and tightly adheres to the inner side of the shell.
[0008] Preferably, the inner protective film comprises:
[0009] an inner layer structure, one side of the inner layer structure faces the core package; and
[0010] The outer layer structure is arranged on a side of the inner layer structure away from the core package. After being heated, the outer layer structure and the inner layer structure shrink and deform and fit tightly to the inner side of the shell.
[0011] Preferably, the outer layer structure is melted onto one side of the inner layer structure.
[0012] Preferably, the outer layer structure is made of polyethylene material.
[0013] Preferably, the inner layer structure is made of polypropylene material.
[0014] Preferably, the four sides of the housing are heated.
[0015] Preferably, the heating temperature of the housing is 75°C - 85°C.
[0016] Preferably, a bottom support plate is provided at the bottom of the core package, and the inner protective film wraps the core package and the bottom support plate together.
[0017] Preferably, the battery cell includes a core package, an electrolyte, a housing, and a protective film wrapped around the outside of the core package. The protective film is the inner protective film mentioned above. The housing is used to encapsulate the core package, and the inner protective film is wrapped around the core package.
[0018] Preferably, a plurality of core packages are provided, and the inner protective film is wrapped around the outside of the plurality of core packages.
[0019] Advantages of the present utility model:
[0020] The core package is wrapped with the inner protective film. The core package and the inner protective film are assembled into the housing. By heating the outside of the housing, the heat is conducted through the housing to the inner protective film. The heated inner protective film shrinks and tightly adheres to the inner side of the housing. Thus, in the subsequent liquid injection process, the contact between the electrolyte and the housing is avoided, ensuring that the electrolyte fills the outside of the core package, reducing the waste of the electrolyte, and achieving the insulation effect between the internal charged body and the housing to a great extent. Description of the drawings
[0021] Figure 1 It is a schematic structural diagram of the inner protective film in the embodiment of the present utility model.
[0022] In the figure:
[0023] 1. Inner protective film; 11. Inner layer structure; 12. Outer layer structure; 2. Bottom support plate; 3. Housing. Detailed implementation manners
[0024] The present utility model will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present utility model, rather than limiting the present utility model. Additionally, it should be noted that for the sake of description, only parts related to the present utility model are shown in the drawings, rather than all the structures.
[0025] In the description of the present utility model, unless otherwise clearly defined and limited, the terms "connected", "connected to", and "fixed" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.
[0026] In the present utility model, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "over", and "on" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "under", and "beneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.
[0027] In the description of this embodiment, the orientation or positional relationships such as "above", "below", "right", etc. are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present utility model. In addition, the terms "first" and "second" are only used for distinction in description and do not have special meanings.
[0028] This embodiment provides an electric core, which includes a core package (not shown in the figure), electrolyte (not shown in the figure), a housing 3, and a protective film. The protective film is coated on the outside of the core package, and the protective film and the core package are arranged inside the housing 3. Specifically, the core package includes a positive electrode sheet, a negative electrode sheet, and a separator. The laminated core body is formed by laminating them in sequence according to the stacking process of the positive electrode sheet, the separator, and the negative electrode sheet, or the wound core body is formed by winding them in the order of the positive electrode sheet, the separator, and the negative electrode sheet. The electrolyte is filled in the housing 3, and the housing 3 is used to encapsulate the core package.
[0029] Preferably, the housing 3 is one of aluminum and stainless steel. The housing 3 of this embodiment is an aluminum shell.
[0030] During the manufacturing process of lithium batteries, the excess electrolyte often fills the empty space inside the electric core, especially at the bottom of the electric core. On the one hand, since the protective film wrapped around the core package hinders the entry of the bottom electrolyte to a certain extent, resulting in insufficient infiltration of the core package in the later stage; on the other hand, the powder falling off from the electrode sheet mixes into the bottom electrolyte, and it is easy to corrode with the aluminum shell over time.
[0031] In order to solve the above problems, combined Figure 1 As shown, this embodiment provides an inner protective film, wherein the inner protective film 1 is coated on the outside of the core package, and the inner protective film 1 and the core package are arranged in the shell 3. The inner protective film 1 is used to isolate the direct contact between the core package and the shell 3. The inner protective film 1 is deformed by heat and fits tightly to the inner side of the shell 3.
[0032] It can be understood that the core package is wrapped with the inner protective film 1, and the core package and the inner protective film 1 are assembled into the shell 3. By heating the outside of the shell 3, the heat is conducted to the inner protective film 1 through the shell 3, and the heated inner protective film 1 shrinks and fits tightly on the inner side of the shell 3, thereby avoiding the contact between the electrolyte and the shell 3 in the subsequent liquid injection process, ensuring that the electrolyte is filled on the outside of the core package, reducing the waste of the electrolyte, and achieving the insulation effect between the internal charged body and the shell 3 to a great extent. Specifically, the inner protective film 1 includes an inner layer structure 11 and an outer layer structure 12, one side of the inner layer structure 11 faces the core package, and the outer layer structure 12 is arranged on the side of the inner layer structure 11 away from the core package. The outer layer structure 12 and the inner layer structure 11 shrink and deform after heating and fit tightly on the inner side of the shell 3.
[0033] Preferably, the outer layer structure 12 is a film made of polyethylene (PE) material. Polyethylene is a thermoplastic obtained by polymerization of ethylene monomers, has high volume resistivity, small dielectric constant, good insulation performance, and a melting point of 120°-130°.
[0034] Preferably, the inner layer structure 11 is a film made of polypropylene (PP) material. Polypropylene is a polymer formed by addition polymerization of propylene, that is, a synthetic resin material, whose dielectric loss factor is in a relatively low range, dielectric constant is small, and has excellent electrical insulation properties, and its melting point is 155°-165°. In addition, the inner layer structure 11 made of polypropylene material also has good mechanical properties, is not easy to deform when subjected to pressure and extrusion, and can play a certain protective role on the core package. Furthermore, in the process of making the inner protective film 1, a hot melt process is used to melt the outer layer structure 12 into one side of the inner layer structure 11, so that the connection between the inner layer structure 11 and the outer layer structure 12 is tight and the integrity is better. In this embodiment, a heating element (not shown in the figure) is used to heat the shell. The heating element is a clamp with heating devices on all four sides. The clamp is clamped on the four sides of the shell 3 to heat the four sides of the shell 3. The heating temperature of the heating element is 75°C-85°C, and the heating temperature is kept uniform during the heating process. Preferably, the heating temperature of this embodiment is 80°C. In other embodiments, it can also be 75°C, 76°C, 77°C, 78°C, 79°C, 81°C, 82°C, 83°C, 84°C or 85°C.
[0035] It should be noted that the outer structure 12 and the inner structure 11 are fused together, and the heating temperature during melting is higher than the temperature for heating the housing 3.
[0036] Among them, a plurality of core packages are provided, and the inner protective film 1 is coated on the outside of the plurality of core packages. In this embodiment, two core packages are provided. In other embodiments, the number of core packages can also be three, four, five or even more. This embodiment does not make specific limitations in this regard. For the case where a plurality of core packages are provided, coating the inner protective film 1 can, on the one hand, isolate the core packages from the housing 3, prevent the bottom electrode plate from directly contacting the housing 3, and play an insulating role; on the other hand, it can play a role in fixing the plurality of core packages.
[0037] In another embodiment, one core package is provided, and the inner protective film 1 is coated on the outside of one core package.
[0038] Furthermore, a bottom support plate 2 is provided at the bottom of the core package, and the inner protective film 1 coats the core package and the bottom support plate 2 together. The correspondence of a plurality of core packages to one bottom support plate 2 facilitates the coating of the inner protective film 1. The bottom support plate 2 further isolates the core package from the housing 3, avoids the powder falling off the electrode plate from mixing into the bottom electrolyte and corroding with the housing 3, and prolongs the service life of the battery cell.
[0039] Obviously, the above-mentioned embodiments of the present utility model are merely examples for clearly explaining the present utility model, rather than limitations on the implementation manners of the present utility model. For those of ordinary skill in the art, various obvious changes, re-adjustments and substitutions can be made without departing from the protection scope of the present utility model. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present utility model shall be included within the protection scope of the claims of the present utility model.
Claims
1. Inner protective film, characterized in that: The inner protective film (1) is coated on the outside of the core package. The inner protective film (1) and the core package are arranged in a shell (3). The inner protective film (1) is used to isolate the core package from direct contact with the shell (3). The inner protective film (1) is deformed by heat and tightly adheres to the inner side of the shell (3).
2. The inner protective film according to claim 1, characterized in that: The inner protective film (1) comprises: an inner layer structure (11), one side of the inner layer structure (11) faces the core package; and An outer layer structure (12), wherein the outer layer structure (12) is arranged on a side of the inner layer structure (11) facing away from the core package, and when heated, the outer layer structure (12) and the inner layer structure (11) shrink and deform and fit tightly to the inner side of the shell (3).
3. The inner protective film according to claim 2, characterized in that: The outer layer structure (12) is melted onto one side of the inner layer structure (11).
4. The inner protective film according to claim 2, characterized in that: The outer layer structure (12) is made of polyethylene material.
5. The inner protective film according to claim 2, characterized in that: The inner layer structure (11) is made of polypropylene material.
6. The inner protective film according to claim 1, characterized in that: The surroundings of the shell (3) are heated.
7. The inner protective film according to claim 1 or 2, characterized in that: The heating temperature of the shell (3) is 75°C-85°C.
8. The inner protective film according to claim 1 or 2, characterized in that: A bottom support plate (2) is provided at the bottom of the core package, and the inner protective film (1) covers the core package and the bottom support plate (2) together.
9. A battery cell, characterized in that: It comprises a core package, an electrolyte, a shell (3) and a protective film coated on the outside of the core package, wherein the protective film is the inner protective film according to any one of claims 1 to 8, the shell (3) is used to encapsulate the core package, and the inner protective film (1) is wrapped around the outside of the core package.
10. The battery cell according to claim 9, characterized in that: A plurality of core packages are provided, and the inner protective film is coated on the outside of the plurality of core packages.