Protective film, battery cell, battery pack and vehicle
By designing a high-porosity, low-porosity structure and a liquid storage pore group in the protective film, the problem of uneven electrolyte distribution in the battery cell is solved, thereby improving the battery cell's service life and safety performance.
Patent Information
- Application Number
- CN202422961590.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-02
- Publication Date
- 2025-12-09
- Estimated Expiration
- 2034-12-02
AI Technical Summary
Uneven distribution of electrolyte along the height of the battery cell leads to uneven chemical reactions, affecting the battery cell's lifespan and safety performance.
A protective membrane is designed with high porosity in the region near the top of the core and low porosity in the region at the bottom. An electrolyte storage pore group is set to store electrolyte. The problem of uneven electrolyte distribution is improved by the design of porosity and electrolyte storage pores.
By optimizing the porosity of the protective film and the design of the electrolyte reservoir, the uniformity of electrolyte distribution along the height of the cell is improved, the consistency of chemical reactions in the cell is enhanced, the cell lifespan is extended, and safety performance is improved.
Smart Images
Figure CN223651436U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the technical field of electric core, concretely relates to protection film, electric core, battery pack and vehicle. BACKGROUND
[0002] The electric core comprises a shell, a protection film arranged in the shell, a core body arranged in the protection film, and an electrolyte arranged in the protection film.
[0003] The researchers found that during use of the electric core, the electrolyte would accumulate at the lower end of the inner protection film due to gravity, resulting in uneven distribution of the electrolyte in the height direction of the core body. SUMMARY
[0004] The embodiments of the utility model provide a protection film, an electric core, a battery pack and a vehicle, which can improve the technical problem of uneven distribution of electrolyte in the height direction of the electric core.
[0005] In a first aspect, the embodiments of the utility model provide a protection film, which is used for coating the peripheral side of a core body of an electric core, is provided with a liquid storage hole group on the side facing the core body, and is used for storing electrolyte.
[0006] In an embodiment, the porosity of the protection film gradually decreases in the first direction.
[0007] In an embodiment, the liquid storage hole group comprises a plurality of liquid storage holes.
[0008] In the first direction, the pore diameter of the plurality of liquid storage holes gradually decreases, and / or the depth of the plurality of liquid storage holes gradually decreases.
[0009] In an embodiment, the liquid storage hole group comprises a plurality of liquid storage rows, the liquid storage row comprises a plurality of liquid storage holes, the plurality of liquid storage rows are arranged at intervals in the first direction, and the plurality of liquid storage holes are arranged at intervals in the extension direction of the first edge.
[0010] In an embodiment, the liquid storage hole group comprises a plurality of liquid storage holes, and the pore diameter of the liquid storage hole is between 10 μm and 100 μm.
[0011] In an embodiment, the protective film comprises a first film layer provided with the reservoir hole group, and a second film layer stacked with the first film layer, the reservoir hole group comprises a plurality of reservoir holes, the reservoir holes penetrate through the first film layer along the thickness direction of the first film layer, and the second film layer is used for plugging one end of the reservoir holes.
[0012] In an embodiment, the porosity of the first film layer is between 30% and 70%.
[0013] In an embodiment, the material of the first film layer is configured as PP or PE.
[0014] In an embodiment, the material of the second film layer is configured as PP or PE.
[0015] In an embodiment, the thickness of the protective film is between 0.1mm and 0.2mm.
[0016] In a second aspect, the embodiments of the utility model provide a battery cell, the battery cell comprises a core body and the foregoing protective film, and the protective film is used for coating the peripheral side of the battery cell.
[0017] In a third aspect, the embodiments of the utility model provide a battery pack, the battery pack comprises the foregoing battery cell.
[0018] In a fourth aspect, the embodiments of the utility model provide a vehicle, the vehicle comprises the foregoing battery pack.
[0019] The embodiments of the utility model have the beneficial effects of:
[0020] In the embodiments of the utility model, the porosity of the area close to the first edge of the protective film is greater than the porosity of the area close to the second edge, so that the amount of electrolyte that can be stored by the area close to the first edge of the protective film is greater than the amount of electrolyte that can be stored by the area close to the second edge. In this way, when the electrolyte is distributed less close to the top end of the core body and more close to the bottom end of the core body, the protective film can supplement more electrolyte for the place close to the top end of the core body and supplement less electrolyte for the place close to the bottom end of the core body. This makes the amount of electrolyte close to the top end of the core body and the amount of electrolyte close to the bottom end of the core body tend to be consistent, thereby improving the problem of uneven distribution of electrolyte in the height direction of the core body. BRIEF DESCRIPTION OF DRAWINGS
[0021] In order to more clearly illustrate the technical solutions in the embodiments of the utility model, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the utility model, and other drawings can also be obtained according to these drawings without creative labor for those skilled in the art.
[0022] Figure 1 is a perspective view of a protective film provided by the embodiment of the present application;
[0023] Figure 2 is Figure 1 is a partial enlarged view of the protective film at A in the embodiment of the present application;
[0024] Figure 3 is Figure 1 is a structural view of the protective film along a first direction in the embodiment of the present application;
[0025] Figure 4 is Figure 3 is a sectional view of the protective film at B-B in the embodiment of the present application;
[0026] Figure 5 is Figure 4 is a structural view of the protective film in the embodiment of the present application.
[0027] Explanation of reference numerals:
[0028] 100, protective film;
[0029] 110, first edge;
[0030] 120, second edge;
[0031] 200, first film layer;
[0032] 300, second film layer;
[0033] 400, liquid storage hole group;
[0034] 410, liquid storage row;
[0035] 411, liquid storage hole. DETAILED DESCRIPTION
[0036] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application. In the present application, the positional words such as "upper" and "lower" generally refer to the upper and lower in the actual use or working state of the device, and specifically refer to the direction of the drawing in the drawings. And "inner" and "outer" refer to the contour of the device.
[0037] The electric core comprises a shell, a protective film arranged in the shell, a core arranged in the protective film, and an electrolyte arranged in the protective film.
[0038] The researchers find that, during the use of the electric core, the electrolyte will accumulate at the lower end of the inner protective film due to gravity, so that the electrolyte is unevenly distributed in the height direction of the core. Specifically, the electrolyte is less distributed near the top end of the core, and more distributed near the bottom end of the core. This makes the electric core have a high degree of uneven chemical reaction during use.
[0039] Therefore, the utility model provides a protective film, aiming at improving the technical problem of uneven distribution of electrolyte in the height direction of the electric core.
[0040] Reference Figures 1 to 5 In an embodiment of the utility model, the protective film 100 is used to coat the peripheral side of the core of the electric core. It should be noted that this should not be understood in a narrow sense that the protective film 100 is only used to coat the peripheral side of the core of the electric core. This should be understood in a broad sense, that is, the protective film 100 is at least used to coat the peripheral side of the core of the electric core. Exemplarily, the protective film 100 can also coat the bottom of the core. It can be understood that the "exemplarily" mentioned in this paper is only as an example of enumeration, and is not intended to limit the protection scope of the application. In addition, the "coating" mentioned in this paper should be understood in a broad sense, that is, "at least partially coating".
[0041] When the protective film 100 is applied to the electric core, the basic structure of the electric core comprises a shell, the electric core comprises a shell, a protective film 100 arranged in the shell, a core arranged in the protective film 100, and an electrolyte arranged in the protective film 100. It should be noted that the core comprises positive and negative electrodes and other basic components for realizing the release of electric energy, and the composition of the electric core will not be described here.
[0042] It is worth mentioning that, if the electric core also comprises an outer protective film 100 coated on the outer surface of the shell, the protective film 100 provided by the utility model can be called an inner protective film 100 at this time.
[0043] The researchers find that the electrolyte will be gradually consumed during the use of the electric core, which makes the service life of the electric core lower. In the related art, the shell of the electric core is usually made larger in volume, so that more electrolyte can be contained in the shell, so as to make the electric core have enough electrolyte to be consumed by injecting more electrolyte into the shell, thereby improving the service life of the electric core. However, this is not conducive to the miniaturization of the electric core.
[0044] In order to facilitate the miniaturization of the battery cell, in an embodiment, the protective film 100 is provided with a liquid storage hole group 400 on the side facing the core body, and the liquid storage hole group 400 is used to store the electrolyte. In this way, the protective film 100 provides a space for accommodating the injected electrolyte. Thus, the battery cell does not need to increase the amount of electrolyte in the battery cell by expanding the volume of the shell. It can be understood that the protective film 100 is not only used to avoid direct contact between the electrolyte and the shell, but also serves as a component for accommodating the electrolyte.
[0045] The protective film 100 has a first edge 110 and a second edge 120 arranged opposite along a first direction, the first edge 110 is used to be arranged close to the top end of the core body, and the second edge 120 is used to be arranged close to the bottom end of the core body. The porosity of the area close to the first edge 110 of the protective film 100 is greater than the porosity of the area close to the second edge 120. It should be noted that the porosity here refers to the porosity of the protective film 100 with respect to the liquid storage hole group 400. In addition, it can be understood that the liquid storage hole group 400 includes a plurality of liquid storage holes 411.
[0046] This makes the area close to the first edge 110 of the protective film 100 store more electrolyte than the area close to the second edge 120. In this way, when the electrolyte is less distributed close to the top end of the core body and more distributed close to the bottom end of the core body, the protective film 100 can supplement more electrolyte close to the top end of the core body and less electrolyte close to the bottom end of the core body. This makes the amount of electrolyte close to the top end of the core body and the amount of electrolyte close to the bottom end of the core body tend to be consistent, thereby improving the problem of uneven distribution of electrolyte in the height direction of the core body.
[0047] In addition, by slowly releasing the electrolyte through the protective film 100, the SEI film of the battery cell can be repaired, the positive and negative plates can be fully infiltrated, the growth rate of the DCR can be reduced, and the cycle life and safety performance of the battery cell can be improved.
[0048] It is worth mentioning that in the manufacturing process of the battery cell, it is possible to use one protective film 100 to coat the core body, that is, the protective film 100 at least has a coating state for coating the core body. It can be understood that at this time, the protective film 100 needs to be bent to adapt to the transition place of the side and the bottom of the battery cell, and the edge of the protective film 100 after bending can be called the second edge 120. Of course, in the manufacturing process of the battery cell, it is also possible to use multiple protective films 100 to splice to coat the core body, and the protective film 100 mentioned in the utility model is the protective film 100 for coating the side of the core body.
[0049] In an embodiment, the porosity of the protective film 100 gradually decreases in the first direction. This makes the porosity of the area of the protective film 100 closer to the second edge 120 smaller, further facilitating the amount of electrolyte near the top end of the core and the amount of electrolyte near the bottom end of the core to be consistent, so as to improve the problem of uneven distribution of electrolyte in the height direction of the core. In order to facilitate more intuitive understanding, assuming that a cutting surface with a normal direction as the first direction is used to cut the protective film 100, during the movement of the cutting surface closer to the second edge 120, the porosity of the protective film 100 on the side closer to the first edge 110 of the cutting surface gradually decreases.
[0050] In some other embodiments, in the first direction, the protective film 100 can be divided into a plurality of sequentially arranged areas, using the concept of the cutting surface mentioned above, during the movement of the cutting surface in the first direction and in any area, the porosity of the protective film 100 on the side closer to the first edge 110 of the cutting surface changes or remains unchanged, if the cutting surface is located between two adjacent areas, and the cutting surface is closer to the second edge 120, then the total porosity of the protective film 100 on the side closer to the first edge 110 of all areas of the cutting surface is smaller.
[0051] In an embodiment, the liquid storage hole group 400 includes a plurality of liquid storage holes 411, and in the first direction, the pore diameters of the plurality of liquid storage holes 411 gradually decrease. The larger the pore diameter of the liquid storage hole 411, the higher the flowability of the electrolyte in the liquid storage hole 411. Since the electrolyte is less distributed near the top end of the core and more distributed near the bottom end of the core, the protective film 100 shell quickly replenishes electrolyte near the top end of the core and slowly replenishes electrolyte near the bottom end of the core. This facilitates the amount of electrolyte near the top end of the core and the amount of electrolyte near the bottom end of the core to be consistent, thereby improving the problem of uneven distribution of electrolyte in the height direction of the core.
[0052] In some other embodiments, the liquid storage hole group 400 includes a plurality of liquid storage holes 411, and in the first direction, the pore diameters of the plurality of liquid storage holes 411 are consistent. In this way, the production and manufacture of the protective film 100 are facilitated.
[0053] There are many ways to control the size of the porosity, in an embodiment, the liquid storage hole group 400 includes a plurality of liquid storage holes 411, and in the first direction, the depths of the plurality of liquid storage holes 411 gradually decrease. In some other embodiments, the liquid storage hole group 400 includes a plurality of liquid storage holes 411, and in the first direction, the depths of the plurality of liquid storage holes 411 gradually increase.
[0054] In an embodiment, the liquid storage hole group 400 includes a plurality of liquid storage rows 410, and the liquid storage row 410 includes a plurality of liquid storage holes 411. The plurality of liquid storage rows 410 are arranged at intervals along the first direction, and the plurality of liquid storage holes 411 are arranged at intervals along the extension direction of the first edge 110. In this way, the liquid storage hole group 400 is more regular, which is convenient for the production and manufacture of the protective film 100.
[0055] In an embodiment, the liquid storage hole group 400 includes a plurality of liquid storage holes 411, and the aperture of the liquid storage hole 411 is between 10 μm and 100 μm. The smaller the aperture, the lower the flowability of the electrolyte in the liquid storage hole 411, and the larger the aperture, the lower the structural strength of the protective film 100. When the aperture of the liquid storage hole 411 is between 10 μm and 100 μm, the flowability of the electrolyte in the liquid storage hole 411 is relatively high, and the structural strength of the protective film 100 is relatively high. Exemplarily, the aperture value of the liquid storage hole 411 can be, but is not limited to, 20 μm, 34 μm, 40 μm, 53 μm, 67 μm, 72 μm, 88 μm, 94 μm, etc., which is not limited herein.
[0056] In an embodiment, the protective film 100 includes a first film layer 200 provided with a liquid storage hole group 400, and a second film layer 300 arranged in a stacked manner with the first film layer 200. The liquid storage hole group 400 includes a plurality of liquid storage holes 411, and the liquid storage hole 411 penetrates the first film layer 200 along the thickness direction of the first film layer 200. The second film layer 300 is used to block one end of the liquid storage hole 411. In this way, the second film layer 300 not only blocks one end of the liquid storage hole 411, but also provides support for the first film layer 200 to improve the structural strength of the protective film 100. In addition, by dividing the protective film 100 into the first film layer 200 and the second film layer 300, it is also convenient for the liquid storage hole 411 to be formed and the first film layer 200.
[0057] In some other embodiments, the protective film 100 has only one film layer, and at this time the liquid storage hole 411 of the liquid storage hole group 400 is in the form of a blind hole. In still some other embodiments, more film layers can be stacked between the first film layer 200 and the second film layer 300.
[0058] It is worth mentioning that if the protective film 100 has only two layers, that is, only the first film layer 200 and the second film layer 300, at this time the second film layer 300 is used to connect with the inner side of the shell of the battery cell. Further, the side of the second film layer 300 away from the first film layer 200 can be configured as a complete sealing surface, so that the second film layer 300 and the shell are sealed and fitted, which is also conducive to reducing the infiltration of the electrolyte between the shell and the second film layer 300, thereby reducing the occurrence of electrolyte leakage due to the corrosion of the electrolyte to the shell.
[0059] In an embodiment, the porosity of the first film layer 200 is between 30% and 70%. The smaller the porosity, the less electrolyte is stored, and the greater the porosity, the lower the structural strength of the protective film 100. When the porosity of the first film layer 200 is between 30% and 70%, the protective film 100 can store more electrolyte and has a higher structural strength. For example, the porosity of the first film layer 200 can be 31%, 37%, 43%, 45%, 54%, 63%, 68%, etc., but is not limited thereto.
[0060] In an embodiment, the material of the first film layer 200 is PP or PE. It can be understood that PP is polypropylene and PE is polyethylene. PP and PE have excellent chemical resistance, which can avoid being eroded by electrolyte. PP and PE have good aging resistance, which can maintain their physical properties for a long time. PP and PE also have good flexibility, which facilitates the protective film 100 to cover the core. PP and PE also have good thermal stability, so that the first film layer 200 will not be decomposed and deformed at a high temperature. The raw materials of PP and PE are abundant, so that the production cost of the first film layer 200 is low. In some other embodiments, the material of the first film layer 200 can also be configured as other materials according to actual needs, which is not limited herein.
[0061] In an embodiment, the material of the second film layer 300 is PP or PE. It can be understood that PP is polypropylene and PE is polyethylene. PP and PE have excellent chemical resistance, which can avoid being eroded by electrolyte. PP and PE have good aging resistance, which can maintain their physical properties for a long time. PP and PE also have good flexibility, which facilitates the protective film 100 to cover the core. PP and PE also have good thermal stability, so that the second film layer 300 will not be decomposed and deformed at a high temperature. The raw materials of PP and PE are abundant, so that the production cost of the second film layer 300 is low. In some other embodiments, the material of the second film layer 300 can also be configured as other materials according to actual needs, which is not limited herein.
[0062] In an embodiment, the materials of the first film layer 200 and the second film layer 300 are different, which makes the performance of the first film layer 200 and the performance of the second film layer 300 can complement each other, and is conducive to improving the performance of the protective film 100.
[0063] For example, the material of the first film layer 200 is PP, and the material of the second film layer 300 is PE; or the material of the first film layer 200 is PE, and the material of the second film layer 300 is PP.
[0064] In an embodiment, the thickness of the protective film 100 is between 0.1 mm and 0.2 mm. If the thickness of the protective film 100 is too thin, the structural strength of the protective film 100 is low and the protective film 100 is easy to break. If the thickness of the protective film 100 is too thick, the protective film 100 occupies too much space in the battery cell shell, which is not conducive to increasing the amount of electrolyte. Therefore, when the thickness of the protective film 100 is between 0.1 mm and 0.2 mm, the structural strength of the protective film 100 is high and the protective film 100 is not easy to break, and the volume of the protective film 100 is small, which reduces the aperture of the protective film 100 in the battery cell shell and is conducive to increasing the amount of electrolyte.
[0065] In a second aspect, the embodiments of the utility model provide a battery cell, the battery cell includes a core body and the foregoing protective film 100, the protective film 100 adopts all the technical solutions of the foregoing embodiments, and therefore at least has all the beneficial effects brought by the technical solutions of the foregoing embodiments, which will not be repeated here. The protective film 100 of the battery cell is used to coat the peripheral side of the battery cell.
[0066] Without loss of generality, the basic structure of the battery cell includes a shell, the battery cell includes the shell, the protective film 100 arranged in the shell, the core body arranged in the protective film 100, and the electrolyte arranged in the protective film 100. It should be noted that the core body includes positive and negative electrodes and other basic components for releasing electrical energy, and the composition of the battery cell will not be described here.
[0067] The battery cell can be but is not limited to a cylindrical battery cell, a square battery cell, a soft package battery cell, and the like, which will not be limited here.
[0068] It is worth mentioning that when the battery cell is a cylindrical battery cell, the core body at this time can be referred to as a winding core. Exemplarily, the winding core is a cylindrical structure formed by winding a positive electrode sheet, a negative electrode sheet and a separator together.
[0069] In a third aspect, the embodiments of the utility model provide a battery pack, the battery pack includes the foregoing battery cell, and the battery cell adopts all the technical solutions of the foregoing embodiments, and therefore at least has all the beneficial effects brought by the technical solutions of the foregoing embodiments, which will not be repeated here.
[0070] In a fourth aspect, the embodiments of the utility model provide a vehicle including the foregoing battery pack. The battery pack adopts all the technical solutions of the foregoing embodiments, and therefore at least has all the beneficial effects brought by the technical solutions of the foregoing embodiments, which will not be repeated here.
[0071] The above has carried out the detailed introduction to the embodiment of the utility model, the principle and implementation mode of the utility model have been described in this article by applying specific examples, the above embodiment explanation is only for helping understanding the method and its core thought of the utility model; simultaneously, for the technical personnel in the art, according to the thought of the utility model, there will be changes in specific implementation mode and application range, and the above is described, the content of the specification should not be understood as the limitation of the utility model.
Claims
1. A protective film for coating a peripheral side of a core body of an electrode core, characterized by, The protective film is provided with a liquid storage hole group on one side of the core body, the liquid storage hole group is used for storing electrolyte, the protective film has a first edge and a second edge oppositely arranged along a first direction, the first edge is used for being arranged close to a top end of the core body, and the second edge is used for being arranged close to a bottom end of the core body, a porosity of an area close to the first edge of the protective film is greater than a porosity of an area close to the second edge.
2. The protective film according to claim 1, characterized by In the first direction, the porosity of the protective film gradually decreases.
3. The protective film according to claim 1, characterized by The liquid storage hole group includes a plurality of liquid storage holes. In the first direction, the pore diameter of the plurality of liquid storage holes gradually decreases, and / or the depth of the plurality of liquid storage holes gradually decreases.
4. The protective film according to claim 3, characterized by The liquid storage hole group includes a plurality of liquid storage rows, the liquid storage row includes a plurality of liquid storage holes, the plurality of liquid storage rows are arranged at intervals along the first direction, and the plurality of liquid storage holes are arranged at intervals along an extension direction of the first edge.
5. The protective film according to claim 3, characterized by The liquid storage hole group includes a plurality of liquid storage holes, and the pore diameter of the liquid storage hole is between 10 μm and 100 μm.
6. The protective film according to claim 1, characterized by The protective film includes a first film layer provided with the liquid storage hole group and a second film layer arranged in a stack with the first film layer, the liquid storage hole group includes a plurality of liquid storage holes, the liquid storage hole penetrates through the first film layer along a thickness direction of the first film layer, and the second film layer is used for plugging one end of the liquid storage hole.
7. The protective film according to claim 6, characterized in that, The porosity of the first film layer is between 30% and 70%.
8. The protective film according to claim 6, characterized by The material of the first film layer is configured as PP or PE. And / or, the material of the second film layer is configured as PP or PE.
9. The protective film according to any one of claims 1 to 8, characterized in that, The thickness of the protective film is between 0.1 mm and 0.2 mm.
10. An electric cell characterized by The battery cell includes a core body and the protective film according to any one of claims 1 to 9, and the protective film is used for wrapping a peripheral side of the battery cell.
11. A battery pack, characterized by The battery cell includes the battery cell according to claim 10.
12. A vehicle characterized by comprising: The battery pack includes the battery pack according to claim 11.