Battery cell insulation film, battery cell, and battery pack

Abstract

The utility model relates to lithium battery technical field and provide a kind of electric core insulating film, electric core and battery package.The electric core insulating film includes insulating film main body, and insulating film main body includes base layer, and the function layer capable of absorbing or releasing electrolyte;Base layer is made of polypropylene or polyethylene;Function layer is located at the side of base layer, and function layer is made of porous sponge, porous elastic polyurethane material or ceramic fiber porous material.The utility model electric core insulating film, utilize the function layer being set, electrolyte can be adsorbed, and be stored in pore, simultaneously, using the capillary action formed by the porous structure of material, electrolyte in the bottom of electric core can be transported to electric core middle part or top, adjust the distribution of electrolyte in electric core pole group, reduce the difference of electrolyte in pole group upper and lower part, and in the process of charge and discharge, function layer can adsorb excess electrolyte or release stored electrolyte, so as to can promote electric core capacity consistency, prolong electric core cycle life.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery technology, and in particular to a cell insulating film. It also relates to a cell having the aforementioned insulating film, and a battery pack having the aforementioned cell. Background Technology

[0002] Prismatic batteries are widely used in electric vehicles, energy storage systems, and consumer electronics due to their high energy density and compact structure. Their core component is the cell electrode assembly (a stacked structure consisting of a positive electrode, a negative electrode, and a separator), which must be encased in an insulating film to provide mechanical protection and insulation. The electrolyte is the key medium for ion transport within the battery; its uniform wetting and cycle efficiency directly affect the battery's capacity, cycle life, and safety.

[0003] Currently, the insulating film of prismatic batteries is mostly made of smooth plastic film, whose main function is to isolate the electrode assembly from the external structure and prevent short circuits. However, after the electrode assembly is inserted into the casing and electrolyte is injected, the electrolyte tends to accumulate at the bottom under the influence of gravity, while the upper part of the electrode assembly is far from the electrolyte source and is insufficiently wetted. This results in a significant difference in ion exchange efficiency between the upper and lower parts of the electrode assembly, affecting the consistency of battery capacity.

[0004] In addition, during the charging and discharging process of square batteries, the electrodes (especially the negative electrode) expand in volume due to the insertion / extraction of lithium ions, which will squeeze the electrolyte. This causes some electrolyte to be squeezed out from the gap between the electrodes. The squeezed-out electrolyte cannot effectively fill the squeezed-out position, which can easily lead to electrolyte waste or local drying. Utility Model Content

[0005] In view of this, the present invention aims to provide a battery cell insulating film that can regulate the distribution of electrolyte within the battery cell electrode assembly.

[0006] To achieve the above objectives, the technical solution of this utility model is implemented as follows:

[0007] A battery cell insulating film includes an insulating film body, the insulating film body including a base layer and a functional layer capable of absorbing or releasing electrolyte;

[0008] The base layer is made of polypropylene or polyethylene;

[0009] The functional layer is disposed on one side of the base layer, and the functional layer is made of porous sponge, porous elastic polyurethane material or ceramic fiber porous material.

[0010] Furthermore, the pore size of the functional layer is between 5μm and 50μm.

[0011] Furthermore, the porosity of the functional layer is between 30% and 70%.

[0012] Furthermore, the thickness d of the functional layer satisfies: 0.1mm≤d≤2mm.

[0013] Furthermore, the base layer has a bottom covering portion, a first side covering portion, and a second side covering portion. The bottom covering portion is connected to the first side covering portion on both sides along the first direction, and each first side covering portion is connected to the second side covering portion on both sides along the second direction. The functional layer is disposed on the bottom covering portion and the two opposite second side covering portions.

[0014] Furthermore, the ratio i between the width of the bottom covering portion and the width of the functional layer disposed on the bottom covering portion satisfies: 2 / 3 ≤ i ≤ 8 / 9.

[0015] Compared with the prior art, this utility model has the following advantages:

[0016] (1) The battery cell insulating film of this utility model has a functional layer set on the base layer. The functional layer is made of porous sponge, porous elastic polyurethane or ceramic fiber porous material. The porous structure of the material forms a capillary effect. After the electrode assembly is filled into the shell, it can adsorb the electrolyte and store it in the pores. At the same time, under the capillary effect of the porous structure, the electrolyte at the bottom of the battery cell can be transported to the middle or top of the battery cell, which can adjust the distribution of electrolyte in the battery cell electrode assembly and reduce the difference of electrolyte between the upper and lower parts of the electrode assembly. Moreover, when the electrode expands and squeezes the electrolyte during charging, the functional layer can adsorb the excess electrolyte. When discharging or the electrode shrinks, the functional layer can release the stored electrolyte, thereby improving the uniformity of battery cell capacity, reducing electrolyte loss and extending the battery cell cycle life.

[0017] (2) By limiting the pore size of the functional layer, the electrolyte delivery efficiency and storage capacity can be balanced, avoiding the absorption rate of the electrolyte being affected by the pore size being too small, or the electrolyte storage capacity being reduced due to the pore size being too large.

[0018] (3) By limiting the gaps in the functional layer, the electrolyte storage capacity and the mechanical strength of the insulating film can be balanced, avoiding insufficient liquid absorption due to low porosity, which would prevent the electrolyte from being effectively stored and released, or loose material structure due to high porosity, which would make it easy to be squeezed and damaged by the electrode assembly.

[0019] (4) By limiting the thickness of the functional layer, the requirements for the electrode assembly can be met without affecting the battery volume.

[0020] (5) Functional layers are provided in the bottom covering part and the two opposite second side covering parts. This not only saves the setting of functional layers, but also allows direct absorption of the electrolyte accumulated at the bottom and transport of the electrolyte accumulated at the bottom to the second side covering part, that is, transporting the electrolyte at the bottom to the middle or top of the electrode group.

[0021] (6) Limiting the width of the functional layer on the bottom coating portion can prevent the coating effect of the bottom of the electrode assembly from being too large, or the absorption of the electrolyte from being too small.

[0022] This utility model also proposes a battery cell in which the electrode assembly is covered with the battery cell insulating film as described above.

[0023] The battery cell of this invention, by adopting the aforementioned battery cell insulating film and utilizing the structure and material properties of the functional layer, can transport the electrolyte from the bottom of the battery cell to the middle or top of the battery cell, adjust the distribution of the electrolyte within the battery cell electrode assembly, reduce the difference in electrolyte between the upper and lower parts of the electrode assembly, and during the charging and discharging process, the functional layer can absorb excess electrolyte or release and refill the stored electrolyte, thereby improving the uniformity of battery cell capacity, reducing electrolyte loss, and extending the battery cell cycle life.

[0024] This utility model also proposes a battery pack, in which the above-mentioned battery cells are provided.

[0025] The battery pack described in this utility model, by using the aforementioned battery cells, can improve the uniformity of the electrolyte within the cell electrode assembly, reduce the difference in electrolyte between the upper and lower parts of the electrode assembly, and during the charging and discharging process, the functional layer can absorb excess electrolyte or release and refill the stored electrolyte, thereby improving the consistency of cell capacity, reducing electrolyte loss, extending cell cycle life, and thus improving the quality and service life of the battery pack. Attached Figure Description

[0026] The accompanying drawings, which form part of this utility model, are used to provide a further understanding of the utility model. The illustrative embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute an undue limitation of the utility model. In the drawings:

[0027] Figure 1 This is a partial cross-sectional view of the battery cell insulating film described in an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the outer structure of the battery cell insulating film according to an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the inner side of the battery cell insulating film according to an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of another structure of the inner side of the battery cell insulating film according to an embodiment of the present invention;

[0031] Figure 5 This is a structural schematic diagram of the battery cell insulating film in application state according to an embodiment of the present invention;

[0032] Explanation of reference numerals in the attached figures:

[0033] 1. Insulating film body; 2. Battery cell housing;

[0034] 10. Base layer; 20. Functional layer; 100. Electrode group; 101. Bottom covering portion; 102. First side covering portion; 103. Second side covering portion. Detailed Implementation

[0035] To make the technical solution and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0037] Furthermore, in the description of this utility model, it should be noted that if terms such as "upper," "lower," "inner," or "outer" appear, indicating orientation or positional relationship, they are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. In addition, if terms such as "first" or "second" appear, they are also used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0038] Furthermore, in the description of this utility model, unless otherwise explicitly defined, the terms "installation," "connection," "joining," and "connector" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model in light of the specific circumstances.

[0039] In this utility model, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0040] The present invention will now be described in detail through exemplary embodiments. However, it should be understood that, without further description, elements, structures, and features in one embodiment may be advantageously incorporated into other embodiments.

[0041] An embodiment of the first aspect of this utility model provides a cell insulating film that covers the outside of the electrode assembly and is housed in the cell housing. By optimizing the structure of the cell insulating film, the distribution of electrolyte in the cell electrode assembly can be adjusted, thereby reducing the difference in electrolyte between the upper and lower parts of the electrode assembly and improving the consistency of cell capacity.

[0042] In existing technologies, the electrode assembly of the battery cell, as the core component of a prismatic battery, needs to be wrapped in an insulating film, which provides mechanical protection and insulation. The electrolyte is the key medium for ion transport within the battery, and its uniform wetting and cycle efficiency directly affect the battery's capacity, cycle life, and safety.

[0043] Currently, the insulating film of prismatic batteries is mostly made of smooth plastic film, whose main function is to isolate the electrode assembly from the external structure and prevent short circuits. However, after the electrode assembly is inserted into the casing and electrolyte is injected, the electrolyte tends to accumulate at the bottom under the influence of gravity, while the upper part of the electrode assembly is far from the electrolyte source and is insufficiently wetted. This results in a significant difference in ion exchange efficiency between the upper and lower parts of the electrode assembly, affecting the consistency of battery capacity.

[0044] In addition, during the charging and discharging process of square batteries, the electrodes (especially the negative electrode) expand in volume due to the insertion / extraction of lithium ions, which will squeeze the electrolyte. This causes some electrolyte to be squeezed out from the gap between the electrodes. The squeezed-out electrolyte cannot effectively fill the squeezed-out position, which can easily lead to electrolyte waste or local drying.

[0045] In view of this, in order to overcome the shortcomings of the prior art, the cell insulating film of this embodiment incorporates... Figures 1 to 4 As shown, the overall design includes an insulating film body 1, which includes a base layer 10 and a functional layer 20 capable of absorbing or releasing electrolyte.

[0046] The base layer 10 is made of polypropylene or polyethylene. The base layer 10 encapsulates the electrode assembly 100 and provides sufficient mechanical support and insulation. The functional layer 20 is located on one side of the base layer 10 and is made of porous sponge, porous elastic polyurethane material, or porous ceramic fiber material. The functional layer 20 is positioned on the side of the base layer 10 facing the electrode assembly 100, meaning it is in contact with both the electrode assembly 100 and the electrolyte.

[0047] Therefore, by setting the functional layer 20 on the base layer 10, the functional layer 20 is made of porous sponge, porous elastic polyurethane or ceramic fiber porous material. The porous structure of the material forms capillary action, which can adsorb electrolyte and store it in the pores after the electrode assembly 100 is filled into the shell. At the same time, under the capillary action of the porous structure, the electrolyte at the bottom of the cell can be transported to the middle or top of the cell, which can adjust the distribution of electrolyte in the electrode assembly 100 and reduce the difference of electrolyte between the upper and lower parts of the electrode assembly 100. Moreover, when the electrode expands and squeezes the electrolyte during charging, the functional layer 20 can adsorb excess electrolyte. When discharging or the electrode shrinks, the functional layer 20 can release the stored electrolyte, thereby improving the cell capacity consistency, reducing electrolyte loss and extending the cell cycle life.

[0048] It should be noted that the functional layer 20 does not react with the electrolyte. Furthermore, in specific implementations, the functional layer 20 is bonded to the substrate layer 10, for example, through thermal bonding. It is also worth noting that the functional layer 20 can completely cover one side of the substrate layer 10, or it can cover only a portion of the substrate layer 10, depending on the specific design requirements.

[0049] Based on the above overview, specifically, the battery cell insulating film includes an insulating film body 1, which includes a base layer 10 and a functional layer 20. The functional layer 20 is disposed on the side of the base layer 10 facing the electrode assembly 100, and is made of porous sponge, porous elastic polyurethane material, or porous ceramic fiber material.

[0050] Combination Figures 1 to 4 As shown, in some exemplary embodiments, the base layer 10 has a bottom covering portion 101, a first side covering portion 102, and a second side covering portion 103. The bottom covering portion 101 is connected to the first side covering portion 102 on both sides along a first direction, and each first side covering portion 102 is connected to the second side covering portion 103 on both sides along a second direction. Furthermore, a functional layer 20 is provided on the bottom covering portion 101 and the two opposing second side covering portions 103.

[0051] In specific implementation, the bottom covering portion 101 is used to cover the bottom of the electrode assembly 100, the first side covering portion 102 is used to cover the large surface of the electrode assembly 100, and the second side covering portion 103 is used to cover the side surface connected to the large surface. At this time, the functional layer 20 is set on the bottom covering portion and the two opposite second side covering portions 103. In this way, the targeted structural design can not only save the setting of the functional layer 20, but also directly absorb the electrolyte accumulated at the bottom and transport the electrolyte accumulated at the bottom to the second side covering portion 103, that is, transport the electrolyte at the bottom to the middle or top of the electrode assembly 100.

[0052] It is worth noting that the two opposing second side covering portions 103 can be as follows: Figure 3 As shown, two opposite portions on the same first side covering 102 can also be as follows: Figure 4 As shown, there are two opposite portions on different first side covering portions 102. In a specific implementation, the second side covering portion 103 with the functional layer 20 contacts the side of the electrode group 100, while the second side covering portion 103 without the functional layer 20 is folded and attached to the outside of the second side covering portion 103 with the functional layer 20.

[0053] In some exemplary embodiments, for example, the ratio i between the width of the bottom covering portion 101 and the width of the functional layer 20 disposed on the bottom covering portion 101 satisfies: 2 / 3 ≤ i ≤ 8 / 9. In specific implementations, this ratio i is set to, for example, 2 / 3, 3 / 4, 4 / 5, 5 / 6, 6 / 7, 7 / 8, or 8 / 9. In this case, by limiting the width of the functional layer 20 on the bottom covering portion 101, it is possible to avoid the coating effect at the bottom of the electrode assembly 100 being too large, or the absorption of the electrolyte being too small.

[0054] In some exemplary embodiments, for example, the pore size of the functional layer 20 is between 5 μm and 50 μm. Specifically, the pore size of the functional layer 20 can be set to, for example, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, or 50 μm. By limiting the pore size of the functional layer 20, both electrolyte transport efficiency and storage capacity can be balanced, avoiding the absorption rate of the electrolyte being affected by an excessively small pore size, or the electrolyte storage capacity being reduced by an excessively large pore size.

[0055] In some exemplary embodiments, for example, the porosity of the functional layer 20 is between 30% and 70%. Specifically, the porosity of the functional layer 20 can be set to, for example, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70%. By limiting the porosity of the functional layer 20, the electrolyte storage capacity and the mechanical strength of the insulating film can be balanced. This avoids insufficient electrolyte absorption due to excessively low porosity, preventing effective storage and release of the electrolyte, or excessively high porosity leading to a loose material structure that is easily damaged by the electrode assembly 100.

[0056] In some exemplary embodiments, for example, the thickness d of the functional layer 20 satisfies: 0.1mm ≤ d ≤ 2mm. In specific implementations, the thickness of the functional layer 20 can be set to, for example, 0.1mm, 0.3mm, 0.5mm, 0.7mm, 1mm, 1.3mm, 1.5mm, 1.7mm, or 2mm. By limiting the thickness of the functional layer 20, the encapsulation requirements of the electrode assembly 100 can be met without affecting the battery volume.

[0057] Reference Figure 5 As shown, the insulating film body 1 covers the outer side of the electrode assembly 100 and is housed within the inner cavity of the cell housing 2, which is also filled with electrolyte for wetting the electrode assembly 100. The insulating film body 1 is illustrated by taking an example where the functional layer 20 is disposed on the bottom covering portion 101 and two opposing second side covering portions 103. Specifically, the functional layer 20 is in direct contact with the sides of the electrode assembly 100. During electrolyte absorption, the functional layer 20 actively adsorbs the electrolyte through capillary action and stores it in its pores. Furthermore, utilizing the capillary action formed by the porous structure of the functional layer 20 material, the electrolyte accumulated at the bottom is dispersed... Figure 5 The arrows in the diagram indicate the electrolyte movement path, delivering it to the middle and upper parts of the cell.

[0058] During cell charging, the electrode expands and squeezes the electrolyte, while the sponge layer absorbs excess electrolyte. During cell discharge or electrode shrinkage, in the backfilling stage, the sponge layer releases the stored electrolyte, allowing it to be backfilled to the extrusion position to replenish the insufficient electrolyte area in the upper part of the electrode assembly 100.

[0059] It is worth noting that, regarding the battery cell insulating film of this embodiment, based on the above exemplary embodiments, in specific implementation, as a preferred embodiment, it is still made by... Figures 1 to 5 As shown, it includes an insulating film body 1, which includes a base layer 10 and a functional layer 20 capable of absorbing or releasing electrolyte. The base layer 10 is made of polypropylene or polyethylene, and the functional layer 20 is disposed on the side of the base layer 10 facing the electrode assembly 100. The functional layer 20 is made of porous sponge, porous elastic polyurethane material, or ceramic fiber porous material.

[0060] The substrate 10 includes a bottom covering portion 101, a first side covering portion 102, and a second side covering portion 103. The bottom covering portion 101 is connected to the first side covering portion 102 on both sides along a first direction, and each first side covering portion 102 is connected to the second side covering portion 103 on both sides along a second direction. The bottom covering portion 101 covers the bottom of the electrode assembly 100. The first side covering portion 102 covers the large surface of the electrode assembly 100. The second side covering portion 103 covers the narrower side adjacent to the large surface. Functional layers 20 are provided on the bottom covering portion 101 and the two opposing second side covering portions 103.

[0061] The ratio i between the width of the bottom covering portion 101 and the width of the functional layer 20 disposed on the bottom covering portion 101 satisfies: 2 / 3≤i≤8 / 9.

[0062] The pore size of the functional layer 20 is between 5μm and 50μm.

[0063] The porosity of functional layer 20 is between 30% and 70%.

[0064] The thickness d of the functional layer 20 satisfies: 0.1mm≤d≤2mm.

[0065] In the above preferred embodiments, the specific settings and arrangements of the position, aperture, gap and thickness of the functional layer 20 can still be referred to the descriptions in the above exemplary embodiments. Furthermore, the beneficial effects brought about by the design of the position, aperture, gap and thickness of the functional layer 20 in this preferred embodiment can also be referred to the descriptions in the above exemplary embodiments.

[0066] The battery cell insulating film of this embodiment adopts the above design. By setting a functional layer 20 on one side of the base layer 10, the functional layer 20 is made of porous sponge, porous elastic polyurethane or ceramic fiber porous material. After the electrode assembly 100 is filled with electrolyte, the functional layer 20 can absorb the electrolyte and store the electrolyte in the pores. At the same time, by utilizing the capillary effect formed by the porous structure of the material, the electrolyte at the bottom of the battery cell can be transported to the middle or top of the battery cell, adjusting the distribution of electrolyte in the battery cell electrode assembly 100 and reducing the difference of electrolyte between the upper and lower parts of the electrode assembly 100.

[0067] Moreover, when the electrode expands and squeezes the electrolyte during charging, the functional layer 20 can absorb excess electrolyte. When discharging or when the electrode contracts, the functional layer 20 can release the stored electrolyte, thereby improving the consistency of cell capacity, reducing electrolyte loss, and extending cell cycle life.

[0068] A second aspect of this utility model provides a battery cell in which the electrode assembly 100 is covered with a battery cell insulating film as described above.

[0069] In this embodiment, the battery cell, by employing the aforementioned battery cell insulating film and utilizing the structure and material properties of the functional layer 20, can transport the electrolyte from the bottom of the battery cell to the middle or top of the battery cell, adjust the distribution of the electrolyte within the battery cell electrode assembly 100, reduce the difference in electrolyte between the upper and lower parts of the electrode assembly 100, and during the charging and discharging process, the functional layer 20 can absorb excess electrolyte or release and refill the stored electrolyte, thereby improving the uniformity of battery cell capacity, reducing electrolyte loss, and extending the battery cell cycle life.

[0070] A third aspect of this utility model provides a battery pack in which the aforementioned battery cells are provided.

[0071] The battery pack of this embodiment, by using the above-mentioned cells, can improve the uniformity of the electrolyte in the cell electrode assembly 100, reduce the difference of electrolyte between the upper and lower parts of the electrode assembly 100, and during the charging and discharging process, the functional layer 20 can absorb excess electrolyte or release and refill the stored electrolyte, thereby improving the consistency of cell capacity, reducing electrolyte loss, extending cell cycle life, and thus improving the quality and service life of the battery pack.

[0072] The above descriptions are merely some embodiments of this utility model and are not intended to limit the utility model. The technical features or structures in the foregoing different embodiments can be arbitrarily combined to form other specific technical solutions as needed. For those skilled in the art, this utility model can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A battery cell insulating film, characterized in that: It includes an insulating film body, which includes a base layer and a functional layer capable of absorbing or releasing electrolyte; The base layer is made of polypropylene or polyethylene; The functional layer is disposed on one side of the base layer, and the functional layer is made of porous sponge, porous elastic polyurethane material or ceramic fiber porous material.

2. The cell insulating film according to claim 1, characterized in that: The pore size of the functional layer is between 5μm and 50μm.

3. The cell insulating film according to claim 1, characterized in that: The porosity of the functional layer is between 30% and 70%.

4. The cell insulating film according to claim 1, characterized in that: The thickness d of the functional layer satisfies: 0.1mm≤d≤2mm.

5. The cell insulating film according to any one of claims 1 to 4, characterized in that: The base layer has a bottom covering portion, a first side covering portion and a second side covering portion. The bottom covering portion is connected to the first side covering portion on both sides along the first direction, and each first side covering portion is connected to the second side covering portion on both sides along the second direction. The functional layer is provided on the bottom covering portion and the two opposite second side covering portions.

6. The cell insulating film according to claim 5, characterized in that: The ratio i between the width of the bottom covering portion and the width of the functional layer disposed on the bottom covering portion satisfies: 2 / 3 ≤ i ≤ 8 / 9.

7. A battery cell, characterized in that: The electrode assembly in the battery cell is covered with the battery cell insulating film according to any one of claims 1 to 6.

8. A battery pack, characterized in that: The battery pack includes the battery cell as described in claim 7.

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