Insulating film, battery cell, and battery pack

Abstract

This utility model relates to the field of battery technology and discloses an insulating film, a battery cell, and a battery pack. The insulating film is used to wrap the electrode assembly of the battery cell to isolate the electrode assembly from the cell casing. It includes: a base film with liquid-passing pores; and a porous material layer wrapped around the outer surface of the base film, which adsorbs the electrolyte inside the cell casing. This utility model, by wrapping a porous material layer on the surface of the base film, can improve the liquid absorption capacity and electrolyte transport capacity of the insulating film. This not only allows the electrolyte to be distributed relatively evenly inside the battery, but also allows the electrolyte to contact each area of ​​the electrode assembly relatively evenly, thereby improving the cycle stability of the electrode assembly and extending the lifespan of the battery cell. Furthermore, since each area of ​​the electrode assembly can contact the electrolyte relatively evenly, the utilization rate of the electrolyte can be improved, reducing the cost of the battery.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to an insulating film, a battery cell, and a battery pack. Background Technology

[0002] Due to gravity, most of the electrolyte inside the battery cell tends to accumulate at the bottom, resulting in uneven electrolyte distribution. This leads to different problems in different areas of the electrode assembly. Specifically, the portion of the electrode assembly near the electrolyte accumulation area will experience lithium plating due to excessive electrolyte immersion, while the portion further away from the electrolyte accumulation area will lack lithium-ion transport channels due to insufficient electrolyte. Clearly, both of these problems shorten the cell's cycle life. Furthermore, uneven electrolyte distribution also leads to electrolyte waste, increasing the cell manufacturing cost. Utility Model Content

[0003] In view of this, the present invention provides an insulating film, a battery cell, and a battery pack to solve the problem of short battery life caused by the poor liquid absorption capacity of existing insulating films.

[0004] In a first aspect, this utility model provides an insulating film for wrapping the electrode assembly of a battery cell to isolate the electrode assembly from the battery cell casing, comprising:

[0005] The base membrane is equipped with liquid passage pores;

[0006] A porous material layer is wrapped around the outer surface of the base film. The porous material layer is used to adsorb the electrolyte inside the cell housing.

[0007] Beneficial Effects: This invention enhances the electrolyte absorption and transport capabilities of the insulating film by coating the surface of the base film with a porous material layer. Specifically, the porous material layer has a large number of micropores on its surface. Therefore, when it comes into contact with the electrolyte inside the battery, it not only adsorbs the electrolyte accumulated at the bottom of the cell onto its own surface but also allows the electrolyte to rise along the surface of the porous material layer. This allows the electrolyte to be distributed relatively evenly within the cell, ensuring that each area of ​​the electrode assembly is in relatively uniform contact with the electrolyte, thereby improving the cycle stability of the electrode assembly and extending the lifespan of the cell. Furthermore, by setting liquid passage holes in the base film, this invention allows more electrolyte to flow to the surface of the electrode assembly, improving electrolyte utilization. Specifically, compared to the surface of the porous material layer closest to the electrode assembly, the surface of the porous material layer furthest from the electrode assembly is blocked by the base film. The electrolyte adsorbed on this surface cannot directly contact the electrode assembly. Therefore, by creating liquid passage holes in the base film, the electrolyte on this surface can directly pass through the base film and reach the electrode assembly surface. This not only further improves electrolyte utilization and reduces electrolyte waste, lowering the cost of the battery cell, but also ensures a long cycle life for the battery cell.

[0008] In one alternative embodiment, the liquid passage is located in the region of the base film near where the electrolyte accumulates inside the cell housing.

[0009] Beneficial effects: This utility model sets the liquid passage hole in the area where the electrolyte accumulates in the cell shell near the base film, which allows the electrode assembly to come into contact with more electrolyte. In this way, the electrolyte can flow to other areas of its own through the electrode assembly, improving the uniformity of electrolyte distribution and utilization rate inside the cell.

[0010] In one optional embodiment, there are multiple liquid passage holes, which are spaced apart on the base membrane.

[0011] Beneficial effects: By setting multiple liquid passage holes, this utility model can further increase the probability of electrolyte contact with the electrode assembly, so that the electrode assembly surface can achieve more complete and uniform wetting.

[0012] In one optional embodiment, the number of liquid passage holes in the region of the base film near the electrolyte accumulation area inside the cell housing is greater than the number of liquid passage holes in the region of the base film away from the electrolyte accumulation area inside the cell housing.

[0013] Beneficial effects: This invention, by differentiating the number of liquid-passing holes, can effectively guide the electrolyte to diffuse rapidly from the accumulation area to the depletion area, significantly improving the electrolyte transport efficiency. Specifically, increasing the number of liquid-passing holes near the electrolyte accumulation area can fully utilize the electrolyte reserve advantage at that location and avoid resource waste; while reducing the number of liquid-passing holes away from the accumulation area can avoid the problem of reduced strength of the base film structure caused by excessive openings.

[0014] In one optional embodiment, the distance between adjacent liquid passages is D1, and the range of D1 is 1cm≤D1≤5cm.

[0015] Beneficial effects: By setting the distance D1 between two adjacent liquid passages according to the above parameters, this utility model not only ensures that the wetting path of the electrolyte on the base film is connected, avoiding insufficient electrolyte supply in local areas of the electrode group due to excessive spacing, but also prevents damage to the mechanical integrity of the base film due to excessive spacing, thus ensuring the support strength and stability of the base film inside the cell.

[0016] In one optional embodiment, the distance between the liquid passage and the edge of the base film is D2, and the range of D2 is 1cm≤D2≤5cm.

[0017] Beneficial effects: By setting the distance between the liquid passage and the edge of the base film to D2 according to the above parameters, this utility model can ensure that the edge of the base film has sufficient structural strength, avoiding damage to the base film caused by mechanical stress concentration during cell assembly, packaging and long-term use, thereby affecting the performance of the cell; on the other hand, it can also ensure that the electrode group located at the edge of the base film can have better contact with the electrolyte, avoiding the problem of local cycle failure of the electrode group due to lack of electrolyte.

[0018] In one optional embodiment, the base film is a polypropylene film, a polyethylene film, or a polyethylene terephthalate film; the porous material layer is an alumina layer.

[0019] Beneficial Effects: This invention uses polypropylene film, polyethylene film, or polyethylene terephthalate film as the base film. This ensures sufficient structural strength of the insulating film and prevents short circuits between the electrode assembly and the battery cell casing, reducing the risk of accidents. The alumina layer, acting as a porous material, provides efficient electrolyte transport channels through its pores, promoting rapid and uniform electrolyte wetting of the electrode assembly. Furthermore, the alumina layer's electrical insulation properties prevent short circuits between the electrode assembly and the battery cell casing. In addition, the alumina layer exhibits good thermal stability, inhibiting deformation or shrinkage of the base film due to high temperatures during battery charging and discharging, thus preventing arcing and fires.

[0020] In one optional embodiment, the thickness of the porous material layer is W1, and the range of W1 is 20um≤W1≤40um; the total thickness of the insulating film is W2, and the range of W2 is 100um≤W2≤300um.

[0021] Beneficial effects: By setting the thickness W1 of the porous material layer and the total thickness W2 of the insulating film according to the above parameters, this utility model can ensure that the insulating film has sufficient liquid absorption capacity and electrolyte transport capacity, while avoiding excessive occupation of the internal space of the battery cell by the insulating film, thus ensuring the energy density of the battery cell itself.

[0022] Secondly, this utility model also provides a battery cell, comprising:

[0023] The shell has an internal cavity containing an electrolyte.

[0024] The pole group is located within the cavity;

[0025] The aforementioned insulating film is wrapped around the outside of the electrode assembly and disposed within the cavity, with at least a portion of the insulating film immersed in the electrolyte.

[0026] Beneficial effects: The battery cell of this utility model includes the insulating film as described above, and has all the beneficial technical effects of the insulating film, which will not be repeated here.

[0027] Thirdly, this utility model also provides a battery pack, including the aforementioned battery cell.

[0028] Beneficial effects: The battery pack of this utility model includes the battery cell as described above, and has all the beneficial technical effects of the battery cell, which will not be repeated here. Attached Figure Description

[0029] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1 This is a front view of an insulating film according to an embodiment of the present utility model;

[0031] Figure 2 This is a schematic diagram of the assembly of the insulating film and the electrode assembly according to an embodiment of the present invention;

[0032] Figure 3 for Figure 2 A schematic diagram of the unfolded structure of the insulating film in the middle;

[0033] Figure 4 for Figure 2 A schematic diagram of the unfolded structure of the middle pole group.

[0034] Explanation of reference numerals in the attached figures:

[0035] 1. Base film; 2. Porous material layer; 10. Insulating film; 20. Electrode assembly. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0037] To address the problem of poor liquid absorption capacity of existing insulating films leading to shortened battery life, this invention provides an insulating film, a battery cell, and a battery pack.

[0038] The following is combined with Figures 1 to 4 The following describes embodiments of the present invention.

[0039] According to embodiments of the present invention, on the one hand, such as Figure 1 and Figure 3 As shown, an insulating film 10 is provided for wrapping the electrode assembly 20 of a battery cell to isolate the electrode assembly 20 of the battery cell from the battery cell housing, comprising: a base film 1 and a porous material layer 2.

[0040] Specifically, the base membrane 1 is provided with liquid passage holes; the porous material layer 2 is wrapped around the outer surface of the base membrane 1, and the porous material layer 2 is used to adsorb the electrolyte inside the battery cell housing.

[0041] This embodiment of the invention enhances the liquid absorption and electrolyte transport capabilities of the insulating film 10 by coating the surface of the base film 1 with a porous material layer 2. Specifically, the surface of the porous material layer 2 has a large number of micropores. Therefore, when it comes into contact with the electrolyte inside the battery, it can not only adsorb the electrolyte accumulated at the bottom of the cell onto its own surface, but also allow the electrolyte to rise along the surface of the porous material layer 2. In this way, the electrolyte can be relatively evenly distributed within the cell, meaning that each area of ​​the electrode assembly 20 can be relatively evenly contacted with the electrolyte, thereby improving the cycle stability of the electrode assembly 20 and extending the lifespan of the cell. Furthermore, this embodiment of the invention allows more electrolyte to flow to the surface of the electrode assembly 20 by providing liquid passage holes on the base film 1, improving the utilization rate of the electrolyte. Specifically, compared to the surface of the porous material layer 2 closest to the electrode assembly 20, the surface of the porous material layer 2 furthest from the electrode assembly 20 is blocked by the base film 1. The electrolyte adsorbed on this surface cannot directly contact the electrode assembly 20. Therefore, by providing liquid passage holes in the base film 1, the electrolyte on this surface can directly pass through the base film 1 and reach the surface of the electrode assembly 20. In this way, not only can the utilization rate of the electrolyte be further improved, electrolyte waste reduced, and cell cost lowered, but the long cycle life of the cell can also be guaranteed.

[0042] It should be noted that the bottom of the cell in this embodiment is determined by the specific layout of the cell within the battery pack. In other words, the location where the electrolyte accumulates within the cell is not unique. For example, taking a square cell as an example, a square cell has a pair of oppositely arranged large faces and a pair of oppositely arranged small faces. If the pair of large faces are arranged along the direction of gravity of the electrolyte, the electrolyte mainly accumulates near the lower large face; if the pair of small faces are arranged along the direction of gravity of the electrolyte, the electrolyte mainly accumulates near the lower small face.

[0043] In addition, in this embodiment, the base film 1 and the porous material layer 2 need to be electrically insulating, so that the electrode group 20 can be isolated from the cell housing, avoiding short circuit between the two.

[0044] According to one embodiment of the present invention, the liquid passage hole is located in the region of the base film 1 near where the electrolyte accumulates inside the cell housing. By placing the liquid passage hole in the region of the base film 1 near where the electrolyte accumulates inside the cell housing, this embodiment allows the electrode assembly 20 to come into contact with more electrolyte. In this way, the electrolyte can flow to other areas of its own via the electrode assembly 20, improving the uniformity and utilization rate of electrolyte distribution within the cell.

[0045] It should be noted that the shape of the liquid passage in this embodiment can be triangular, circular, square, or strip-shaped. Specifically, it can be adapted according to design needs, and this utility model does not impose specific limitations on it. In addition, in order to ensure the liquid passage effect, the diameter of the liquid passage needs to be increased while ensuring the structural strength of the base film 1 itself.

[0046] According to one embodiment of the present invention, there are multiple liquid-passing holes, which are spaced apart on the base film 1. By providing multiple liquid-passing holes, this embodiment can further increase the probability of electrolyte contact with the electrode assembly 20, enabling more thorough and uniform wetting of the electrode assembly 20 surface. For example, the number of liquid-passing holes can be three, five, or seven.

[0047] According to one embodiment of this utility model, the number of liquid-passing holes in the region of the base film 1 near the electrolyte accumulation area inside the cell housing is greater than the number of liquid-passing holes in the region of the base film 1 away from the electrolyte accumulation area inside the cell housing. This embodiment, by differentiating the number of liquid-passing holes, can effectively guide the electrolyte to diffuse rapidly from the accumulation area to the depletion area, significantly improving the electrolyte transport efficiency. Specifically, increasing the number of liquid-passing holes near the electrolyte accumulation area can fully utilize the electrolyte reserve advantage at that location and avoid resource waste; while reducing the number of liquid-passing holes away from the accumulation area can avoid the problem of decreased structural strength of the base film 1 due to excessive openings.

[0048] According to one embodiment of this utility model, the distance between adjacent liquid passage holes is D1, and the range of D1 is 1cm ≤ D1 ≤ 5cm. This embodiment, by setting the distance D1 between two adjacent liquid passage holes according to the above parameters, ensures that the electrolyte wetting path on the base film 1 is interconnected, avoiding insufficient electrolyte supply in local areas of the electrode assembly 20 due to excessive spacing, and also prevents damage to the mechanical integrity of the base film 1 due to excessive spacing, ensuring the supporting strength and stability of the base film 1 inside the battery cell.

[0049] It should be noted that, in addition, the value of D1 in this embodiment can be, but is not limited to, 1cm, 1.1cm, 1.3cm, 1.5cm, 1.7cm, 1.9cm, 2cm, 2.1cm, 2.3cm, 2.5cm, 2.7cm, 2.9cm, 3cm, 3.1cm, 3.3cm, 3.5cm, 3.7cm, 3.9cm, 4cm, 4.1cm, 4.3cm, 4.5cm, 4.7cm, 4.9cm, and 5cm.

[0050] According to one embodiment of this utility model, the distance from the liquid passage hole to the edge of the base film 1 is D2, and the range of D2 is 1cm≤D2≤5cm. By setting the distance from the liquid passage hole to the edge of the base film 1 as D2 according to the above parameters, this embodiment ensures that the edge of the base film 1 has sufficient structural strength, preventing damage to the base film 1 due to mechanical stress concentration during cell assembly, packaging, and long-term use, thus affecting cell performance. Furthermore, it ensures that the electrode assembly 20 located at the edge of the base film 1 can also have good contact with the electrolyte, avoiding the problem of localized cycle failure of the electrode assembly 20 due to electrolyte shortage.

[0051] It should be noted that, in addition, the value of D2 in this embodiment can be, but is not limited to, 1cm, 1.1cm, 1.3cm, 1.5cm, 1.7cm, 1.9cm, 2cm, 2.1cm, 2.3cm, 2.5cm, 2.7cm, 2.9cm, 3cm, 3.1cm, 3.3cm, 3.5cm, 3.7cm, 3.9cm, 4cm, 4.1cm, 4.3cm, 4.5cm, 4.7cm, 4.9cm, and 5cm.

[0052] According to one embodiment of this utility model, the base film 1 is a polypropylene film, a polyethylene film, or a polyethylene terephthalate film; the porous material layer 2 is an alumina layer. This embodiment selects a polypropylene film, a polyethylene film, or a polyethylene terephthalate film as the base film 1. On the one hand, this ensures that the insulating film 10 has sufficient structural strength; on the other hand, it prevents short circuits between the electrode assembly 20 and the battery cell casing, reducing the occurrence of safety accidents. The alumina layer is used as the porous material layer 2. On the one hand, its pores provide efficient transport channels for the electrolyte, promoting rapid and uniform wetting of the electrode assembly 20; on the other hand, the alumina layer has electrical insulation properties, thus preventing short circuits between the electrode assembly 20 and the battery cell casing. Furthermore, the alumina layer has good thermal stability, which can suppress the deformation or shrinkage of the base film 1 due to high temperatures when heat is generated during battery charging and discharging, avoiding adverse consequences such as arcing and fire.

[0053] According to one embodiment of this utility model, the thickness of the porous material layer 2 is W1, where W1 ranges from 20µm to 40µm; the total thickness of the insulating film 10 is W2, where W2 ranges from 100µm to 300µm. By setting the thickness W1 of the porous material layer 2 and the total thickness W2 of the insulating film 10 according to the above parameters, this embodiment can ensure that the insulating film 10 has sufficient liquid absorption and electrolyte transport capabilities while avoiding excessive occupation of the internal space of the battery cell, thus guaranteeing the energy density of the battery cell itself.

[0054] It should be noted that, in addition, the value of W1 in this embodiment can be, but is not limited to, 20um, 21um, 22um, 23um, 24um, 25um, 26um, 27um, 28um, 29um, 30um, 31um, 32um, 33um, 34um, 35um, 36um, 37um, 38um, 39um, and 40um. Furthermore, the value of W2 in this embodiment can be, but is not limited to, 100um, 110um, 120um, 130um, 140um, 150um, 160um, 170um, 180um, 190um, 200um, 210um, 220um, 230um, 240um, 250um, 260um, 270um, 280um, 290um, and 300um.

[0055] According to an embodiment of the present invention, on the other hand, as... Figures 2 to 4 As shown, a battery cell is also provided, including: a housing, an electrode group 20 and the aforementioned insulating film 10.

[0056] Specifically, the shell has an internal cavity containing an electrolyte; the electrode assembly 20 is located within the cavity; the insulating film 10 is wrapped around the outside of the electrode assembly 20 and located within the cavity, with at least a portion of the insulating film 10 immersed in the electrolyte.

[0057] The battery cell of this embodiment includes the insulating film 10 as described above, and has all the beneficial technical effects of the insulating film 10, which will not be repeated here.

[0058] It should be noted that the battery cells in this embodiment can be, but are not limited to, prismatic battery cells and blade battery cells.

[0059] According to an embodiment of the present invention, another aspect provides a battery pack including the aforementioned battery cell. The battery pack of this embodiment includes the battery cell described above and possesses all the beneficial technical effects of that battery cell, which will not be repeated here.

[0060] The technical effects of this utility model will be described below with reference to specific embodiments and comparative examples.

[0061] Table 1

[0062]

[0063] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. An insulating film for wrapping the electrode assembly of a battery cell to isolate the electrode assembly from the battery cell housing, characterized in that, include: The base membrane is equipped with liquid passage pores; A porous material layer is wrapped around the outer surface of the base film, and the porous material layer is used to adsorb the electrolyte inside the cell housing; There are multiple liquid passage holes, which are spaced apart on the base film; the distance between adjacent liquid passage holes is D1, and the range of D1 is 1cm≤D1≤5cm; the distance between each liquid passage hole and the edge of the base film is D2, and the range of D2 is 1cm≤D2≤5cm. The number of liquid passage holes in the base film near the electrolyte accumulation area inside the cell housing is greater than the number of liquid passage holes in the base film away from the electrolyte accumulation area inside the cell housing. Alternatively, the liquid passage hole is located in the region of the base film near where the electrolyte accumulates inside the cell housing.

2. The insulating film according to claim 1, characterized in that, The base membrane is a polypropylene membrane, a polyethylene membrane, or a polyethylene terephthalate membrane; the porous material layer is an alumina layer.

3. The insulating film according to claim 1, characterized in that, The thickness of the porous material layer is W1, and the range of W1 is 20um≤W1≤40um; the total thickness of the insulating film is W2, and the range of W2 is 100um≤W2≤300um.

4. A battery cell, characterized in that, include: The shell has an internal cavity containing an electrolyte. The pole group is located within the cavity; The insulating film according to any one of claims 1 to 3 is wrapped around the outside of the electrode assembly and disposed in the cavity, with at least a portion of the insulating film immersed in the electrolyte.

5. A battery pack, characterized in that, include: The battery cell as described in multiple claims 4.

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