Battery cell and battery pack

Abstract

A battery cell and a battery pack, which relate to the technical field of lithium ion batteries. The battery cell comprises a battery case, an insulating film, and a bare cell core, wherein the bare cell core is arranged in an accommodating cavity of the case, the bare cell core having two first bare core side surfaces which are arranged opposite each other in the direction of thickness of the bare cell core; the insulating film is arranged in the accommodating cavity, the insulating film comprising two first side film portions attached to the first bare core side surfaces; and the bare cell core is sandwiched between the two first side film portions, the thickness of each first side film portion being gradually reduced from the middle to two ends in the direction of height H of the bare cell core. The battery pack comprises the battery cell. According to the battery cell and battery pack provided in the present application, a reactive force from the battery case can be distributed by means of the structure of the insulating film, making the reactive force relatively uniformly distributed on the insulating film and transmitted to the bare cell core, thereby preventing or delaying the continued expansion and deformation of the bare cell core.

Description

Battery cells and battery packs

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application number 202322186982.5 filed with the State Intellectual Property Office of China on August 14, 2023, entitled “Battery Cell and Battery Pack,” the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the technical field of lithium-ion batteries, and in particular to a battery cell and a battery pack. Background Art

[0004] With the depletion of fossil fuels and growing awareness of energy conservation and emission reduction, the development of green energy technologies and battery energy storage technologies has become inevitable. Lithium-ion batteries, with their numerous advantages such as large capacity, light weight, high energy density, long cycle life, environmental friendliness, and lack of memory effect, have become the primary energy storage material for electronic products such as electric vehicles and smartphones.

[0005] Among them, the battery cells of power batteries are mainly square aluminum shells, including bare cells, aluminum shells and top covers. Bare cells are prepared by winding or stacking the positive and negative pole pieces and separators. Insulating films (also known as Mylar films) are placed on both sides of the bare cells in the thickness direction for insulation protection, and then further wrapped in aluminum shells. Currently, the insulating film is generally a flat plate structure with uniform thickness after unfolding, which only serves as insulation protection. In practical applications, this is difficult to meet the requirements.

[0006] During the use of wound power batteries, the bare cells will generate heat and expand, and the expansion force in the middle of the bare cells is generally larger. After expansion, the bare cells tend to bulge in the middle and stick to the insulating film first, and then deform together with the insulating film and squeeze the aluminum shell, thereby affecting the fit of the bare cells. This can easily lead to gaps of varying degrees between the positive electrode sheet, the negative electrode sheet, and the separator (such as a large gap in the middle and small gaps on both sides), which increases the lithium ion transmission path and reduces the electrochemical performance of the lithium ion battery.

[0007] Summary of the Invention

[0008] The present application provides a battery cell and a battery pack, which can to a certain extent solve the technical problem in the related art that the middle part of the bare cell bulges due to heat expansion of the bare cell, which easily causes the bare cell to deform.

[0009] Some embodiments of the present application provide the following technical solutions:

[0010] A battery cell may include a shell, an insulating film and a bare cell;

[0011] The battery housing has a housing cavity, and the bare cell is arranged in the housing cavity;

[0012] The bare core has two first bare core side surfaces arranged opposite to each other along the thickness direction of the bare core;

[0013] The insulating film is disposed in the housing cavity, and includes two first side film portions spaced apart from each other; the two first side film portions are respectively disposed corresponding to the two first bare core side surfaces, and the bare cell is sandwiched between the two first side film portions;

[0014] Along the height direction of the bare battery core, the thickness of the first side film portion decreases from the middle to both ends.

[0015] In any of the above technical solutions, optionally, the insulating film may further include a bottom film portion, and two ends of the bottom film portion are respectively connected to one side of the first side film portion along the height direction of the bare cell;

[0016] The bare core further includes a first bare core bottom surface and a first bare core top surface that are arranged opposite to each other along the height direction of the bare core, and the bottom surface film portion is in contact with the first bare core bottom surface.

[0017] In any of the above technical solutions, optionally, the bare core may further include two second bare core side surfaces arranged opposite to each other along the length direction of the bare core; and the insulating film may further include two second side surface film portions respectively attached to the second bare core side surfaces;

[0018] The two first side membrane portions, the two second side membrane portions and the bottom membrane portion enclose and form a membrane cavity for accommodating the bare battery cell.

[0019] In any of the above technical solutions, optionally, a plurality of through holes may be provided on the bottom film portion; and the plurality of through holes penetrate the bottom film portion along the height direction of the bare cell.

[0020] In any of the above technical solutions, optionally, the two first side film portions, the two second side film portions and the one bottom film portion can be enclosed to form a film cavity for accommodating the bare cell.

[0021] In any of the above technical solutions, optionally, when the two first side membrane portions, the two second side membrane portions and the bottom membrane portion enclose a membrane cavity for accommodating the bare battery cell, the second side membrane portions on both sides of the first side membrane portion may overlap or partially overlap.

[0022] In any of the above technical solutions, optionally, along the thickness direction of the bare battery cell, the first side surface film portion of the insulating film has an inner surface close to the bare battery cell and an outer surface away from the bare battery cell; the inner surface and the first bare core side are in contact, wherein the inner surface of the first side surface film portion is a plane, and the outer surface of the first side surface film portion is a curved surface.

[0023] In any of the above technical solutions, optionally, an outer surface of the first side film portion of the insulating film is at least partially in contact with an inner wall of the battery housing.

[0024] In any of the above technical solutions, along the thickness direction of the bare cell, the sum of the maximum thickness dimensions of the two first side membrane portions may be a closed interval of 6%-15% of the size of the housing cavity.

[0025] In any of the above technical solutions, optionally, the sum of the maximum thickness dimensions of the two first side membrane portions may be a closed interval of 7%-10% of the size of the housing accommodating cavity.

[0026] In any of the above technical solutions, optionally, along the thickness direction of the bare cell, the sum of the maximum thickness dimensions of the two first side membrane portions plus the size of the bare cell may be equal to the size of the shell accommodating cavity.

[0027] In any of the above technical solutions, optionally, along the thickness direction of the bare cell, the sum of the maximum thickness dimensions of the two first side film portions plus the size of the bare cell can be equal to the distance between the two first side film portions.

[0028] In any of the above technical solutions, optionally, in the planar structure of the insulating film, the first side film portion, the bottom film portion and the first side film portion can be connected in sequence along the thickness direction of the bare cell.

[0029] In any of the above technical solutions, optionally, along the length direction of the bare cell, both sides of each first side film portion can be connected to the second side film portion respectively.

[0030] In any of the above technical solutions, optionally, the material of the insulating film can be one of PET plastic, PC plastic or PVC plastic.

[0031] In any of the above technical solutions, optionally, the battery shell may be an aluminum shell.

[0032] In any of the above technical solutions, optionally, there may be multiple bare cells, and the multiple bare cells are arranged in sequence along the thickness direction of the bare cells;

[0033] Along the thickness direction of the bare battery cell, the first side surface film portion is attached to the first bare core side surface of the bare battery cell at the end.

[0034] In any of the above technical solutions, optionally, along the thickness direction of the bare cell, the ratio of the maximum thickness dimension of the first side surface film to the minimum dimension of the first side surface film portion may be in the range of 1.5 to 3.

[0035] In any of the above technical solutions, optionally, along the height direction of the bare battery cell, the thickness of the first side film portion is gradually decreased from the middle to both ends to form an arch structure.

[0036] In any of the above technical solutions, optionally, the first side film portion can be fixed to the bare battery cell by gluing or hot melting.

[0037] Other embodiments of the present application further provide a battery pack, which may include the battery cell according to any of the above technical solutions.

[0038] The beneficial effects of this application are mainly:

[0039] The battery cell and battery pack provided in the present application include an insulating film and a bare cell; the thickness of the first side film portion of the insulating film is gradually reduced from the middle to the two ends along the height direction H of the bare cell, forming an arch structure or a similar arch structure; when the bare cell heats up and expands and presses against the insulating film, and squeezes the battery shell together with the insulating film, the reaction force from the battery shell can be decomposed by the structure of the insulating film, and then the reaction force is relatively evenly distributed on the insulating film and transmitted to the bare cell, so as to prevent or delay the bare cell from continuing to expand and deform. Compared with an insulating film with a flat structure, the insulating film structure described in this embodiment can greatly reduce or avoid the technical problem of deformation of the bare cell.

[0040] In order to make the above-mentioned objectives, features and advantages of the present application more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0042] FIG1 is a schematic structural diagram of a battery cell provided in an embodiment of the present application;

[0043] FIG2 is another schematic structural diagram of a battery cell provided in an embodiment of the present application;

[0044] FIG3 is a schematic structural diagram of an insulating film provided in an embodiment of the present application;

[0045] FIG4 is a schematic diagram of the planar structure of the insulating film provided in an embodiment of the present application.

[0046] Icon: 100-insulating film; 110-bottom membrane portion; 120-first side membrane portion; 130-second side membrane portion; 140-membrane cavity; 200-bare cell; 210-bottom surface of first bare core; 220-side surface of first bare core; 230-side surface of second bare core; 240-top surface of first bare core; 300-battery shell; 310-shell accommodating cavity. DETAILED DESCRIPTION

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0048] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0049] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0050] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the products of this application are typically placed when in use. These terms are intended only to facilitate the description of this application and to simplify the description, and are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0051] Furthermore, terms such as "horizontal," "vertical," and "overhanging" do not necessarily imply that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0052] It should also be noted that, in the description of this application, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0053] The following describes some embodiments of the present application in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features therein may be combined with each other.

[0054] Example

[0055] The present embodiment provides a battery cell and a battery pack; please refer to Figures 1 to 4, Figures 1 and 2 are schematic structural diagrams of the battery cell provided in this embodiment, wherein Figure 1 is a cross-sectional view of the battery cell, and Figure 2 is a cross-sectional view of the battery cell shown in Figure 1 rotated 90° from a top view direction; Figure 3 is a schematic structural diagram of the insulating film provided in this embodiment, and Figure 4 is a schematic plan structural diagram of the insulating film shown in Figure 3.

[0056] The battery cell provided in this embodiment can be used in power batteries, such as lithium-ion batteries, and can be used in electric vehicles, electric bicycles, energy storage, and other fields.

[0057] As shown in Figures 1-4, a battery cell may include an insulating film 100 and a bare cell 200. In this embodiment, the battery cell may further include a battery housing 300. The insulating film 100 and the bare cell 200 may both be disposed within the battery housing 300, with the insulating film 100 disposed between the bare cell 200 and the battery housing 300. The bare cell 200 has a height direction H, a length direction L, and a thickness direction T, wherein the height direction H, the length direction L, and the thickness direction T are mutually perpendicular.

[0058] The bare cell 200 may have first bare cell side surfaces 220 disposed opposite to each other along a thickness direction T of the bare cell 200 .

[0059] The insulating film 100 may include two first side surface film portions 120 that are aligned with the first bare core side surface 220. In other words, the first bare core side surface 220 of the bare cell 200 may be aligned with the first side surface film portion 120 of the insulating film 100.

[0060] Along the height direction H of the bare battery cell 200, the thickness of the first side membrane portion 120 is set to decrease from the middle to the two ends, forming an arch structure or a similar arch structure; through this structure, when the bare battery cell 200 heats up and expands and sticks to the insulating film 100, and squeezes the battery shell 300 together with the insulating film 100, the arch structure or the similar arch structure of the insulating film 100 can be used to decompose the reaction force from the battery shell 300, so that the reaction force is relatively evenly distributed on the insulating film 100 and transmitted to the bare battery cell 200, which can effectively prevent or delay the bare battery cell 200 from continuing to expand and deform, thereby avoiding or reducing the poor contact caused by the separation of the positive and negative pole pieces of the bare battery cell 200 to a certain extent, thereby improving the electrochemical performance of the battery pack, and avoiding or reducing the safety hazards caused by excessive squeezing pressure on the middle part of the battery shell 300.

[0061] The battery cell described in this embodiment may include an insulating film 100 and a bare cell 200. The thickness of the first side membrane portion 120 of the insulating film 100 decreases from the middle to both ends along the height direction H of the bare cell 200, forming an arched structure or a similar arched structure. When the bare cell 200 heats up and expands, pressing against the insulating film 100 and squeezing the battery housing together with the insulating film 100, the structure of the insulating film 100 can decompose the reaction force from the battery housing, thereby making the reaction force relatively evenly distributed on the insulating film 100 and transmitted to the bare cell 200, thereby preventing or delaying the bare cell 200 from further expanding and deforming. Compared to an insulating film with a flat structure, the insulating film 100 structure described in this embodiment can greatly reduce or avoid the technical problem of deformation of the bare cell 200.

[0062] In the related art, the insulating film 100 wraps the bare cell 200 and is placed in the battery shell 300, with a certain reserved gap between it and the inner wall of the battery shell 300. During the use of the battery, the bare cell 200 will heat up and expand. The middle part of the bare cell 200 will first bulge and stick to the insulating film 100, and then deform together with the insulating film 100 and squeeze the battery shell 300. The battery cell described in this embodiment improves the structure of the insulating film 100. When the middle part of the bare battery cell 200 first bulges and presses against the insulating film 100, the arched structure or the arch-like structure of the insulating film 100 squeezes the battery shell 300 together with the bare battery cell 200. The reaction force of the battery shell 300 is evenly dispersed by the arched structure or the arch-like structure of the insulating film 100. The action process of the reaction force of the battery shell 300 is shown by the arrows in Figure 1. The dispersed force is relatively evenly transmitted to the bare battery cell 200, which can effectively prevent or delay the bare battery cell 200 from continuing to expand and deform, thereby avoiding or reducing the poor contact caused by the separation of the positive and negative pole pieces of the bare battery cell 200 to a certain extent.

[0063] In the optional scheme of this embodiment, along the thickness direction T of the bare battery cell 200, the ratio range of the maximum thickness dimension of the first side membrane portion 120 to the minimum dimension of the first side membrane portion (120) can be: 1.5~3. Controlling the ratio range of the maximum dimension and the minimum dimension of the thickness direction of the first side membrane portion 120 to 1.5~3 can not only achieve the expansion force of the decomposition of the bare battery cell, but also effectively prevent or delay the continued expansion and deformation of the bare battery cell 200, thereby avoiding or reducing the poor contact caused by the separation of the positive and negative pole pieces of the bare battery cell 200 to a certain extent, and at the same time, it can also minimize the internal space of the battery accommodating cavity occupied by the first side membrane portion, thereby improving the energy density of the battery.

[0064] In this embodiment, the dimension of the first side film portion 120 in the thickness direction can be measured using a vernier caliper or a micrometer.

[0065] The insulating film 100 of this embodiment not only has the function of insulating protection, but also can effectively prevent or reduce the amount of heat expansion and deformation of the bare battery cell 200.

[0066] As shown in FIG. 1 to FIG. 4 , in an optional solution of this embodiment, the insulating film 100 may further include a bottom film portion 110 , which is connected to one side of the first side film portion 120 along the height direction H of the bare cell 200 .

[0067] The bare cell 200 may further include a first bare core bottom surface 210 and a first bare core top surface 240 disposed opposite each other along a height direction H of the bare cell 200, with the bottom surface film portion 110 being in contact with the first bare core bottom surface 210. The bottom surface film portion 110 of the insulating film 100 can provide good insulation protection for the first bare core bottom surface 210 of the bare cell 200.

[0068] As shown in Figures 1 to 4, in an optional solution of this embodiment, the bare cell 200 may further include second bare core side surfaces 230 disposed opposite each other along the length direction L of the bare cell 200; and the insulating film 100 may further include two second side surface film portions 130 that are in contact with the second bare core side surfaces 230. The second side surface film portions 130 of the insulating film 100 can provide good insulation protection for the second bare core side surfaces 230 of the bare cell 200.

[0069] The two first side membrane portions 120, the two second side membrane portions 130, and the bottom membrane portion 110 enclose a membrane cavity 140 for accommodating the bare battery cell 200. For example, the two first side membrane portions 120, the two second side membrane portions 130, and the bottom membrane portion 110 enclose a membrane cavity 140 to accommodate the bare battery cell 200. The membrane cavity 140 is enclosed by the first side membrane portion 120, the second side membrane portion 130, and the bottom membrane portion 110 to accommodate the bare battery cell 200, so as to provide good insulation protection for the bare battery cell 200.

[0070] In an optional solution of this embodiment, the bottom membrane portion 110 may be provided with a plurality of through holes; the plurality of through holes penetrate the bottom membrane portion 110 along the height direction H of the bare cell 200. The plurality of through holes provided on the bottom membrane portion 110 can improve the heat dissipation performance of the bare cell 200 and accelerate the air flow inside and outside the membrane cavity 140.

[0071] As shown in Figures 1 to 4, in an optional solution of this embodiment, along the thickness direction T of the bare cell 200, the first side surface portion 120 of the insulating film 100 may have an inner surface close to the bare cell 200 and an outer surface away from the bare cell 200; wherein the inner surface of the first side surface portion 120 is a plane, and the outer surface of the first side surface portion 120 is a curved surface. By setting the inner surface of the first side surface portion 120 close to the bare cell 200 as a plane, the contact area between the insulating film 100 and the bare cell 200 is increased, so that the insulating film 100 can transfer the reaction force from the battery case 300 to the bare cell 200 relatively evenly. By setting the outer surface of the first side surface portion 120 away from the bare cell 200 as a curved surface, an arched structure or a similar arched structure of the insulating film 100 is formed.

[0072] As shown in Figures 1 and 2, in an optional solution of this embodiment, the battery cell may further include a battery case 300. The battery case 300 may have a case accommodating cavity 310. The bare cell 200 is disposed in the case accommodating cavity 310, and the outer surface of the first side membrane portion 120 of the insulating film 100 at least partially abuts the inner wall of the battery case 300. In this way, by configuring the outer surface of the first side membrane portion 120 of the insulating film 100 to at least partially abut the inner wall of the battery case 300, when the bare cell 200 heats up and expands and squeezes the inner wall of the battery case 300 together with the insulating film 100, the reaction force of the battery case 300 can better act on the first side membrane portion 120 of the insulating film 100.

[0073] Optionally, the battery housing 300 may be an aluminum shell or a shell made of other materials.

[0074] As shown in Figures 1 and 2, in an optional solution of this embodiment, the battery cell may further include a battery case 300, the battery case 300 having a case accommodating cavity 310, and the bare cell 200 is disposed in the case accommodating cavity 310. Along the thickness direction T of the bare cell 200, the sum of the maximum thickness dimensions of the two first side film portions 120 may be 6%-15% of the size of the case accommodating cavity 310. In an optional embodiment of the present application, by setting the sum of the maximum thickness dimensions of the two first side film portions 120 to a closed interval of 6%-15% of the size of the case accommodating cavity 310, the space utilization efficiency of the bare cell 200 and the strength of the insulating film 100 are balanced.

[0075] Optionally, along the thickness direction T of the bare battery cell 200 , the sum of the maximum thickness dimensions of the two first side membrane portions 120 is 6%, 8%, 11%, 12.5% ​​or 15% of the size of the shell accommodating cavity 310 , or other values.

[0076] Optionally, along the thickness direction T of the bare cell 200 , the sum of the maximum thickness dimensions of the two first side membrane portions 120 may be a closed interval of 7%-10% of the size of the shell accommodating cavity 310 .

[0077] As shown in Figures 1 and 2, in an optional solution of this embodiment, the battery cell may further include a battery shell 300, the battery shell 300 having a shell accommodating cavity 310, and the bare cell 200 is arranged in the shell accommodating cavity 310. Along the thickness direction T of the bare cell 200, the sum of the maximum thickness dimensions of the two first side membrane portions 120 plus the size of the bare cell 200 may be equal to the distance between the two first side membrane portions 120. In an embodiment of the present application, the distance between the two first side membrane portions 120 refers to the distance between the outer surfaces of the two first side membrane portions 120. Specifically, the number of first side membrane portions 120 is two, and the sum of the maximum dimensions of the two first side membrane portions 120 plus the dimension in the thickness direction of the cell is equal to the thickness dimension of the accommodating cavity. This arrangement allows the insulating film 100 to better fit the inner wall of the battery shell 300.

[0078] It should be noted that, along the thickness direction T of the bare cell 200, the size of the bare cell and the size of the two first side film portions can be measured using a vernier caliper or a micrometer.

[0079] As shown in FIG. 4 , in an optional solution of this embodiment, in the planar structure of the insulating film 100 , the first side film portion 120 , the bottom film portion 110 and the first side film portion 120 are sequentially connected along the thickness direction T of the bare cell 200 .

[0080] Along the length direction L of the bare cell 200, both sides of each first side membrane portion 120 can be connected to the second side membrane portion 130. When the first side membrane portion 120, the second side membrane portion 130 and the bottom membrane portion 110 are enclosed to form a membrane cavity 140 for accommodating the bare cell 200, the second side membrane portions 130 on both sides of the first side membrane portion 120 overlap or partially overlap.

[0081] In an optional solution of this embodiment, the insulating film 100 is made of one of PET plastic, PC plastic, or PVC plastic, or other materials. PET plastic is a polyethylene terephthalate plastic, PC plastic is a polycarbonate plastic, and PVC plastic is a polyvinyl chloride plastic. Using PET, PC, or PVC plastic as the insulating film material offers high cost-effectiveness, excellent insulation performance, and superior mechanical strength.

[0082] In an optional solution of this embodiment, there may be multiple bare cells 200 , and the multiple bare cells 200 are arranged in sequence along the thickness direction T of the bare cells 200 .

[0083] Along the thickness direction T of the bare cell 200, the first side film portion 120 is attached to the first bare cell side surface 220 of the end bare cell 200. By arranging multiple bare cells 200 in a battery cell, the power of the battery cell can be effectively increased.

[0084] In an optional solution of this embodiment, the first side film portion 120 can be fixed to the bare battery cell 200 by gluing or hot melting. Fixing the first side film portion 120 to the bare battery cell 200 by gluing or hot melting can reduce the processing difficulty and cost of the battery cell to a certain extent.

[0085] The battery cell described in this embodiment may also use other methods to fix the first side film portion 120 and the bare battery cell 200.

[0086] This embodiment also provides a battery pack, which may include the battery cells described in any of the above-mentioned embodiments. In the battery pack of this embodiment, the thickness of the first side membrane portion 120 of the insulating film 100 is gradually reduced from the middle to both ends along the height direction H of the bare cell 200, forming an arch structure or a similar arch structure; when the bare cell 200 heats up and expands and adheres to the insulating film 100, and squeezes the battery shell together with the insulating film 100, the reaction force from the battery shell can be decomposed by the structure of the insulating film 100, and the reaction force is relatively evenly distributed on the insulating film 100 and transmitted to the bare cell 200, so as to prevent or delay the bare cell 200 from continuing to expand and deform. Compared with an insulating film with a flat structure, the insulating film 100 structure described in this embodiment can greatly reduce or avoid the technical problem of deformation of the bare cell 200.

[0087] The battery pack provided in this embodiment may include the battery cells described above. The technical features of the battery cells disclosed above also apply to this battery pack, and the technical features of the battery cells disclosed above are not repeated here. The battery pack described in this embodiment has the advantages of the battery cells described above, and the advantages of the battery cells disclosed above are not repeated here.

[0088] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application. Industrial Applicability

[0089] The present application provides a battery cell and a battery pack, which relate to the technical field of lithium-ion batteries; the battery cell includes a battery shell, an insulating film and a bare cell; the bare cell is arranged in a housing cavity of the shell, and the bare cell has two first bare core side surfaces arranged opposite to each other along the thickness direction of the bare cell; the insulating film is arranged in the housing cavity, and the insulating film includes two first side surface film portions that are in contact with the first bare core side surfaces; the bare cell is sandwiched between the two first side surface film portions, and along the height direction H of the bare cell, the thickness of the first side surface film portions decreases from the middle to both ends. The battery pack includes a battery cell. The present application provides a battery cell and a battery pack, which can decompose the reaction force from the battery shell through the structure of the insulating film, and then make the reaction force relatively evenly distributed on the insulating film and transmitted to the bare cell, so as to prevent or delay the bare cell from continuing to expand and deform.

[0090] Furthermore, it is understood that the battery cells and battery packs of the present application are reproducible and can be used in a variety of industrial applications. For example, the battery cells and battery packs of the present application can be used in the field of lithium-ion battery technology.

Claims

1. A battery cell, wherein: The battery cell comprises a battery housing (300), an insulating film (100) and a bare battery cell (200); The battery housing (300) has a housing accommodating cavity (310), and the bare battery cell (200) is arranged in the housing accommodating cavity (310); The bare battery core (200) has two first bare core side surfaces (220) arranged opposite to each other along a thickness direction (T) of the bare battery core (200); The insulating film (100) is arranged in the housing accommodating cavity (310), and the insulating film (100) comprises two first side film portions (120) arranged at intervals; the two first side film portions (120) are respectively arranged corresponding to the two first bare core side portions, and the bare battery cell (200) is sandwiched between the two first side film portions (120); Along the height direction (H) of the bare battery core (200), the thickness of the first side film portion (120) decreases from the middle to both ends.

2. The battery cell according to claim 1, wherein: The insulating film (100) further comprises a bottom film portion (110), and two ends of the bottom film portion (110) are respectively connected to one side of the first side film portion (120) along the height direction (H) of the bare battery cell (200); The bare core (200) further comprises a first bare core bottom surface (210) and a first bare core top surface (240) arranged relatively to each other along a height direction (H) of the bare core (200), and the bottom surface film portion (110) is in contact with the first bare core bottom surface (210).

3. The battery cell according to claim 2, wherein the bottom membrane portion (110) is provided with a plurality of through holes; the plurality of through holes penetrate the bottom membrane portion (110) along a height direction (H) of the bare battery cell (200).

4. The battery cell according to claim 2, wherein: The bare core (200) further comprises two second bare core side surfaces (230) arranged opposite to each other along the length direction (L) of the bare core (200); the insulating film (100) further comprises two second side surface film portions (130) respectively attached to the second bare core side surfaces (230); The two first side membrane portions (120), the two second side membrane portions (130) and the bottom membrane portion (110) enclose and form a membrane cavity (140) for accommodating the bare battery cell (200).

5. The battery cell according to claim 4, wherein: The two first side membrane portions (120), the two second side membrane portions (130) and the one bottom membrane portion (110) enclose and form a membrane cavity (140) for accommodating the bare battery cell (200).

6. The battery cell according to claim 4, wherein: When the two first side membrane portions (120), the two second side membrane portions (130) and the bottom membrane portion (110) enclose a membrane cavity (140) for accommodating the bare battery cell (200), the second side membrane portions (130) on both sides of the first side membrane portion (120) overlap or partially overlap.

7. The battery cell according to claim 1, wherein: Along the thickness direction (T) of the bare battery core (200), the first side film portion (120) of the insulating film (100) has an inner surface close to the bare battery core (200) and an outer surface away from the bare battery core (200); the inner surface is in contact with the first bare core side surface (220), the inner surface of the first side film portion (120) is a plane, and the outer surface of the first side film portion (120) is a curved surface.

8. The battery cell according to claim 7, wherein: The outer surface of the first side film portion (120) of the insulating film (100) at least partially abuts against the inner wall of the battery case (300).

9. The battery cell according to claim 1, wherein: Along the thickness direction (T) of the bare battery cell (200), the sum of the maximum thickness dimensions of the two first side membrane portions (120) is a closed interval of 6%-15% of the size of the shell accommodating cavity (310), or the sum of the maximum thickness dimensions of the two first side membrane portions (120) is a closed interval of 7%-10% of the size of the shell accommodating cavity (310).

10. The battery cell according to claim 1, wherein: Along the thickness direction (T) of the bare battery core (200), the sum of the maximum thickness dimensions of the two first side membrane portions (120) plus the dimension of the bare battery core (200) is equal to the dimension of the shell accommodating cavity (310).

11. The battery cell according to claim 1, wherein: Along the thickness direction (T) of the bare battery core (200), the sum of the maximum thickness dimensions of the two first side film portions (120) plus the dimension of the bare battery core (200) is equal to the distance between the two first side film portions (120).

12. The battery cell according to claim 2, wherein: In the planar structure of the insulating film (100), the first side film portion (120), the bottom film portion (110) and the first side film portion (120) are sequentially connected along the thickness direction (T) of the bare battery cell (200).

13. The battery cell according to claim 4, wherein: Along the length direction (L) of the bare battery cell (200), two sides of each first side film portion (120) are respectively connected to the second side film portion (130).

14. The battery cell according to claim 1, wherein: The insulating film is made of PET plastic, PC plastic or PVC plastic.

15. The battery cell according to claim 1, wherein: The battery housing (300) is an aluminum housing.

16. The battery cell according to claim 1, wherein: There are a plurality of bare battery cells (200), and the plurality of bare battery cells (200) are arranged in sequence along a thickness direction (T) of the bare battery cells (200); Along the thickness direction (T) of the bare battery core (200), the first side film portion (120) is attached to the first bare core side surface (220) of the bare battery core (200) at the end.

17. The battery cell according to claim 1, wherein: Along the thickness direction (T) of the bare battery cell (200), the ratio of the maximum thickness dimension of the first side film portion (120) to the minimum dimension of the first side film portion (120) is in the range of 1.5 to 3.

18. The battery cell according to claim 1, wherein: Along the height direction (H) of the bare battery cell (200), the thickness of the first side film portion (120) is gradually reduced from the middle to both ends to form an arch structure.

19. The battery cell according to claim 1, wherein: The first side film portion (120) is fixed to the bare battery cell (200) by gluing or hot melting.

20. A battery pack, wherein: The battery pack includes the battery cell according to any one of claims 1 to 19.

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