Battery cell

Abstract

The invention provides a battery cell, and relates to the technical field of batteries. The battery cell comprises a pole group, a cover plate assembly, an insulating sheet and a reinforcing piece, the pole group is connected with the cover plate assembly, and the insulating sheet wraps the pole group; the insulating sheet comprises an insulating main body and a connecting part, the connecting part is connected with one end, in the length direction of the battery cell, of the insulating main body, the connecting part comprises a first binding surface and a second binding surface which are opposite to each other, the first binding surface is bound with the pole group, the reinforcing piece is connected with the second binding surface, and the reinforcing piece is connected with the second binding surface. And the connecting part is connected with the cover plate assembly. Therefore, the reinforcer is connected with the connecting part, which is used for being connected with the cover plate assembly, of the insulating sheet, so that the strength of the connecting part is increased, the risks of wrinkling, damage and the like at the hot melting position of the insulating sheet and the plastic part of the cover plate assembly when the pole group enters the shell are reduced, and the reject ratio of the battery cell is reduced.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell. Background Art

[0002] Lithium-ion batteries have the advantages of large capacity, high operating voltage, strong charge retention ability and long cycle life. They have been widely used in various fields such as transportation power supply, electric energy storage power supply, new energy energy storage power supply, aerospace and military industry.

[0003] The battery cell is the smallest unit of the battery pack of lithium-ion batteries. The battery cell generally includes structures such as the electrode group, electrolyte, insulating sheet, side plate, cover assembly and shell. The cover assembly usually integrates the pole, injection hole and explosion-proof valve. In the battery cell, the shell and the cover assembly are fixedly connected by welding to form a closed space for accommodating the electrode group; the insulating sheet wraps around the electrode group and is fixed with the lower plastic of the cover assembly by hot melting, which plays the role of insulating the electrode group and protecting the electrode group from damage by the shell weld.

[0004] During the assembly of the battery cell, the cover plate assembly and the pole group need to be welded and fixed first, and then the side plate and the insulating sheet are fixed by hot-melt, and the insulating sheet is wrapped on the pole group. At the same time, the two ends of the insulating sheet are fixed by hot-melt to the lower plastic and the end plate of the cover plate assembly respectively, and then the pole group is put into the shell so that the pole group is installed inside the shell. Finally, the cover plate assembly and the shell are welded, thus completing the assembly process of the entire battery cell.

[0005] When the thickness of the insulating sheet is large, it is difficult to bend the insulating sheet when wrapping the electrode group, which will cause the insulating sheet to be loosely attached to the electrode group, resulting in interference with the shell when entering the shell. Therefore, the thickness of the insulating sheet is usually within 0.1mm, and the structural strength of the insulating sheet is limited. During the process of the electrode group entering the shell, due to the limited spacing between the electrode group and the shell, as the depth of the shell increases, the friction between the electrode group and the shell gradually increases. In the length direction of the battery cell, the insulating sheet is increasingly pulled, and the insulating sheet often has problems such as wrinkles and damage at the hot melt position of the lower plastic of the insulating sheet and the cover assembly, resulting in a high defective rate of the battery cell. Summary of the invention

[0006] In view of this, the present application provides a battery cell to solve the problem that during the battery cell assembly process, as the depth of insertion into the shell increases, the friction between the pole group and the shell gradually increases, the insulating sheet is pulled more and more in the length direction of the battery cell, and the insulating sheet is often wrinkled and damaged at the hot-melt position of the lower plastic of the insulating sheet and the cover assembly, resulting in a high defective rate of the battery cell.

[0007] The present application provides a battery cell, the battery cell comprising a pole group, a cover plate assembly, an insulating sheet and a reinforcement member, the pole group is connected to the cover plate assembly, and the insulating sheet covers the pole group;

[0008] The insulating sheet includes an insulating body and a connecting portion, wherein the connecting portion is connected to one end of the insulating body in the length direction of the battery cell, the connecting portion includes a first fitting surface and a second fitting surface facing away from each other, the first fitting surface is fitted to the pole group, the reinforcement is connected to the second fitting surface, and the connecting portion is connected to the cover plate assembly.

[0009] Preferably, an end of the reinforcement member in the length direction facing away from the insulating body is flush with an end of the connecting portion facing away from the insulating body.

[0010] Preferably, the cover plate assembly comprises a plate body and a plastic part, wherein one side of the plastic part in the length direction is in contact with the plate body, and the other side of the plastic part in the length direction is in contact with the pole group;

[0011] The insulating sheet encloses a wrapping space, at least a portion of the plastic component is located inside the wrapping space, and the outer side wall of the plastic component in the length direction and / or width direction is connected to the connecting portion.

[0012] Preferably, a dimension of a portion of the plastic part located inside the insulating sheet in the length direction is smaller than or equal to a dimension of the reinforcement in the length direction.

[0013] Preferably, the dimension of the reinforcement in the length direction is 15 mm-25 mm.

[0014] Preferably, the battery cell also includes a side plate, which is arranged inside the wrapping space, and includes a first connecting surface and a second connecting surface opposite to each other in the width direction of the battery cell, the first connecting surface is in contact with the pole group, and the second connecting surface is in contact with the insulating sheet.

[0015] Preferably, the battery core includes two reinforcing members, the insulating sheet includes two connecting parts, the two connecting parts are respectively connected to two ends of the insulating body in the length direction, and the two reinforcing members are respectively connected to the two connecting parts.

[0016] Preferably, the battery cell comprises two cover plate assemblies, the two cover plate assemblies are respectively arranged on both sides of the pole group in the length direction, and the two connecting parts are respectively connected to the two cover plate assemblies.

[0017] Preferably, the battery cell further comprises a shell, the insulating sheet and the pole group are both arranged inside the shell, the reinforcement is fitted with the shell, and the two cover plate assemblies are respectively connected to both ends of the shell in the length direction.

[0018] Preferably, the reinforcement member is an insulating member.

[0019] In the battery cell of the present application, the battery cell includes a pole group, a cover plate assembly, an insulating sheet and a reinforcement member, the pole group is connected to the cover plate assembly, and the insulating sheet covers the pole group; the insulating sheet includes an insulating body and a connecting portion, the connecting portion is connected to one end of the insulating body in the length direction of the battery cell, the connecting portion includes a first fitting surface and a second fitting surface facing away from each other, the first fitting surface is fitted with the pole group, and the reinforcement member is connected to the second fitting surface. In this way, the reinforcement member is connected to the connecting portion of the insulating sheet used for connecting with the cover plate assembly, so that the strength of the connecting portion is increased, and the risk of wrinkles, breakage, and other problems of the insulating sheet at the position where the plastic part of the cover plate assembly is hot-melted when the pole group is put into the shell is reduced, thereby reducing the defective rate of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. 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 related drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 An exploded view of a battery cell according to an embodiment of the present invention is shown;

[0022] Figure 2 A schematic diagram showing the internal structure of a shell of a battery cell according to an embodiment of the present invention;

[0023] Figure 3 The figure shows the relative position of the insulating sheet and the reinforcing member before being bent.

[0024] Icons: 1-pole group; 2-cover plate assembly; 21-plate body; 22-plastic part; 23-pole; 3-insulating sheet; 31-insulating body; 32-connecting part; 4-reinforcement; 5-side plate; 6-shell; 7-hot melting point; L1-length direction; L2-width direction; L3-thickness direction. DETAILED DESCRIPTION

[0025] The following specific embodiments are provided to help the reader obtain a comprehensive understanding of the methods, devices and / or systems described herein. However, after understanding the disclosure of the present application, various changes, modifications and equivalents of the methods, devices and / or systems described herein will be apparent. For example, the order of operations described herein is merely an example, and is not limited to the order set forth herein, but in addition to the operations that must occur in a particular order, changes that will be apparent after understanding the disclosure of the present application may be made. In addition, in order to improve clarity and brevity, descriptions of features known in the art may be omitted.

[0026] The features described herein may be implemented in different forms and should not be interpreted as being limited to the examples described herein. Rather, the examples described herein have been provided only to illustrate some of the many possible ways of implementing the methods, devices and / or systems described herein that will be apparent after understanding the disclosure of the present application.

[0027] Throughout the specification, when an element (such as a layer, a region, or a substrate) is described as being “on”, “connected to”, “bound to”, “over”, or “covering” another element, it may be directly “on”, “connected to”, “bound to”, “over”, or “covering” another element, or one or more other elements may be present between them. In contrast, when an element is described as being “directly on”, “directly connected to”, “directly bound to”, “directly over”, or “directly covering” another element, there may be no other elements present between them.

[0028] As used herein, the term "and / or" includes any one of the associated listed items and any combination of any two or more items.

[0029] Although terms such as "first," "second," and "third" may be used herein to describe various members, components, regions, layers, or portions, these members, components, regions, layers, or portions are not limited by these terms. Rather, these terms are only used to distinguish one member, component, region, layer, or portion from another member, component, region, layer, or portion. Therefore, without departing from the teachings of the examples described herein, the first member, component, region, layer, or portion referred to may also be referred to as the second member, component, region, layer, or portion.

[0030] For ease of description, spatial relational terms such as "above", "upper", "below", and "lower" may be used herein to describe the relationship of one element to another element as shown in the accompanying drawings. Such spatial relational terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the accompanying drawings. For example, if the device in the accompanying drawings is turned over, an element described as being "above" or "upper" relative to another element will subsequently be "below" or "lower" relative to the other element. Therefore, the term "above" includes both "above" and "below" orientations depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relational terms used herein will be interpreted accordingly.

[0031] The terms used herein are only used to describe various examples and are not used to limit the present disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms "include", "comprise" and "have" list the stated features, quantities, operations, components, elements and / or their combinations that exist, but do not exclude the existence or addition of one or more other features, quantities, operations, components, elements and / or their combinations.

[0032] Variations in the shapes shown in the drawings may occur due to manufacturing techniques and / or tolerances. Therefore, the examples described herein are not limited to the specific shapes shown in the drawings but include variations in shapes that occur during manufacturing.

[0033] The features of the examples described herein may be combined in various ways that will be apparent after understanding the disclosure of the present application. In addition, although the examples described herein have various configurations, other configurations are possible as will be apparent after understanding the disclosure of the present application.

[0034] The present application provides a battery cell, such as Figures 1 to 3 As shown, the battery cell includes a pole group 1, a cover assembly 2, an insulating sheet 3 and a reinforcing member 4, the pole group 1 is connected to the cover assembly 2, and the insulating sheet 3 covers the pole group 1; the insulating sheet 3 includes an insulating body 31 and a connecting portion 32, the connecting portion 32 is connected to one end of the insulating body 31 in the length direction L1 of the battery cell, the connecting portion 32 includes a first fitting surface and a second fitting surface, the first fitting surface is fitted with the pole group 1, the reinforcing member 4 is connected to the second fitting surface, and the connecting portion 32 is connected to the cover assembly 2. In this way, the reinforcing member 4 is connected to the connecting portion 32 of the insulating sheet 3 used for connecting with the cover assembly 2, so that the strength of the connecting portion 32 is increased, and the risk of wrinkles, breakage, etc. of the insulating sheet 3 at the position where the pole group 1 is hot-melted with the plastic part 22 of the cover assembly 2 when the pole group 1 is put into the shell is reduced, thereby reducing the defective rate of the battery cell.

[0035] Optionally, the insulating sheet 3 may be a Mylar film.

[0036] In the embodiments of the present application, Figure 1 and Figure 2As shown, the cover plate assembly 2 includes a plate body 21, a plastic part 22 and a pole 23. One side of the plastic part 22 in the length direction L1 is in contact with the plate body 21, and the other side of the plastic part 22 in the length direction L1 is in contact with the pole group 1. The pole 23 passes through the plate body 21 and the plastic part 22, and the pole lug in the pole group 1 is connected to the pole 23. The insulating sheet 3 is bent into a rectangular parallelepiped shape, thereby enclosing a wrapping space. The pole group 1 is located in the wrapping space, and at least part of the plastic part 22 also extends into the wrapping space. The side wall of the plastic part 22 is in contact with the first surface of the connecting portion 32, and the outer side wall of the plastic part 22 is connected to the connecting portion 32 by hot melting. By providing the reinforcing member 4, the strength of the connecting portion 32 is increased, and the risk of wrinkles, breakage, and other problems of the insulating sheet 3 at the position of hot melting with the plastic part 22 when the pole group 1 is put into the shell is reduced, thereby reducing the defective rate of the battery cell.

[0037] Optionally, the plastic part 22 can be hot-melt connected to the connecting portion 32 only at the two outer walls opposite to each other in the length direction L1, or the plastic part 22 can be hot-melt connected to the connecting portion 32 only at the two outer walls opposite to each other in the width direction L2, or the plastic part 22 can be hot-melt connected to the connecting portion 32 at both the two outer walls opposite to each other in the length direction L1 and the two outer walls opposite to each other in the width direction L2.

[0038] Furthermore, the end of the reinforcing member 4 in the length direction L1 facing away from the insulating body 31 is flush with the end of the connecting portion 32 facing away from the insulating body 31. In other words, the reinforcing member 4 extends from the end of the insulating sheet 3 in the length direction L1 to the middle of the insulating sheet 3 to ensure that the reinforcing member 4 can cover the area of ​​the insulating sheet 3 used for connection with the plastic part 22.

[0039] Optionally, the size of the portion of the plastic part 22 extending into the interior of the insulating sheet 3 in the length direction L1 is less than or equal to the size of the reinforcement member 4 in the length direction L1. In this way, the reinforcement member 4 can completely cover the portion of the plastic part 22 used for heat-melting with the insulating sheet 3, reducing the risk of wrinkles, breakage, and other problems on the insulating sheet 3 at the position where the insulation sheet 3 is heat-melted with the plastic part 22 when the electrode group 1 is placed in the shell.

[0040] Preferably, the two ends of the reinforcing member 4 in the length direction L1 are respectively flush with the two ends of the connecting portion 32 in the length direction L1, that is, the size of the reinforcing member 4 in the length direction L1 is equal to the size of the connecting portion 32 in the length direction L1. In this way, the reinforcing member 4 can completely cover the connecting portion 32 to ensure that the connecting portion 32 has sufficient strength.

[0041] Preferably, the dimension of the reinforcement member 4 in the length direction L1 is 15 mm-25 mm, for example, the dimension of the reinforcement member 4 in the length direction L1 may be 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm or 25 mm, etc. In this way, the dimension of the reinforcement member 4 in the length direction L1 is set to be within the above range, so that the reinforcement member 4 can completely cover the area for connection with the plastic part 22, reducing the risk of the insulation sheet 3 being wrinkled or damaged at the hot-melt position of the lower plastic of the cover plate assembly 2 when the electrode group 1 is put into the shell.

[0042] During the manufacturing process of the battery cell, the insulation coating process includes coating the insulation sheet 3 on the whole composed of the two cover plate assemblies 2, the pole group 1 and the side plate 5, and after the connecting portion 32 is hot-melt connected with the plastic part 22, the whole composed of the insulation sheet 3, the two cover plate assemblies 2, the pole group 1 and the side plate 5 is put into the shell. In the manufacturing process of the battery cell without the reinforcement 4, the yield rate of the insulation coating process is about 97.5%, and the defective rate is about 2.5%. In the case of poor insulation coating process, the poor insulation caused by the damage of the insulation sheet 3 due to the pulling of the connection position between the insulation sheet 3 and the plastic part 22 when entering the shell accounts for about 90%. In order to determine the influence of the size of the reinforcement 4 in the length direction L1 on the yield of the insulation film coating process, reinforcements 4 with different sizes in the length direction L1 are tested, and the test results are as follows:

[0043]

[0044]

[0045]

[0046] Based on the above table, it can be seen that when the size of the reinforcement 4 in the length direction L1 is less than 15mm (Comparative Example 1 and Comparative Example 2 in the above table), there is still a problem of damage to the insulating sheet 3 due to excessive pulling force on the connection position of the insulating sheet 3 and the plastic part 22 when entering the shell, and the yield rate of the insulation coating process is still low; when the size of the reinforcement 4 in the length direction L1 is greater than 25mm (Comparative Example 3, Comparative Example 4 and Comparative Example 5 in the above table), the size of the reinforcement 4 is too large, which will affect the bending effect of the insulating sheet 3, the appearance after coating is irregular, and the friction resistance with the shell is large when entering the shell, and the yield rate of the insulation coating process is still low; when the size of the reinforcement 4 in the length direction L1 is within the range of 15mm-25mm (Examples 1 to 11 in the above table), the proportion of poor insulation caused by damage to the insulating sheet 3 due to pulling on the connection position of the insulating sheet 3 and the plastic part 22 when entering the shell is significantly reduced, and the yield rate of the insulation coating process is increased.

[0047] In addition, if Figure 1As shown, the battery cell also includes a side plate 5, which includes a first connecting surface and a second connecting surface opposite to each other in the width direction L2 of the battery cell, the first connecting surface is in contact with the electrode group 1, and the second connecting surface is in contact with the insulating sheet 3. The side plate 5 is also located in the wrapping space enclosed by the insulating sheet 3.

[0048] Preferably, one side of the electrode group 1 in the width direction L2 is bonded to the first connection surface of the side plate 5, the other side of the electrode group 1 in the width direction L2 is bonded to the insulating sheet 3, and both sides of the electrode group 1 in the thickness direction L3 are bonded to the insulating sheet 3 respectively.

[0049] In an embodiment of the present application, the battery cell includes two reinforcement members 4, and the insulating sheet 3 includes two connecting portions 32, the two connecting portions 32 are respectively connected to the two ends of the insulating body 31 in the length direction L1, and the two reinforcement members 4 are respectively connected to the two connecting portions 32. In other words, the two reinforcement members 4 extend from the two ends of the insulating sheet 3 in the length direction L1 toward the middle of the insulating sheet 3. The battery cell includes two cover plate assemblies 2, the two cover plate assemblies 2 are respectively arranged on both sides of the pole group 1 in the length direction L1, and the two connecting portions 32 are respectively connected by hot melt to the two plastic parts 22 in the two cover plate assemblies 2. By providing two reinforcement members 4, the risk of wrinkles, breakage and other problems in the insulating sheet 3 at the position where the pole group 1 is hot melted with the two plastic parts 22 when the pole group 1 is put into the shell is reduced.

[0050] In addition, the battery cell also includes a shell 6, the insulating sheet 3 and the electrode group 1 are both arranged inside the shell 6, the reinforcement 4 is fitted with the shell 6, and the two cover plate assemblies 2 are respectively connected to the two ends of the shell 6 in the length direction L1. In this way, by arranging the reinforcement 4 on the connecting portion 32 of the insulating sheet 3, it is possible to ensure that the connecting portion 32 has sufficient structural strength, so as to reduce the risk of the insulating sheet 3 being wrinkled, damaged, etc. at the hot melting position of the lower plastic of the insulating sheet 3 and the cover plate assembly 2 when the electrode group 1 is inserted into the shell.

[0051] Optionally, the reinforcing member 4 is an insulating member to ensure the insulation effect between the pole group 1 and the shell 6. The reinforcing member 4 can be a structure that can play an insulating role, such as an insulating tape, a rubber sheet, etc. When the reinforcing member 4 is an insulating tape, the reinforcing member 4 can be directly bonded to the connecting portion 32. When the reinforcing member 4 is a structure that does not have a rubber layer, such as a rubber sheet, the reinforcing member 4 can be bonded to the connecting portion 32 by an insulating adhesive.

[0052] Before the insulating sheet 3 is bent, Figure 3 As shown, the insulating sheet 3 is in sheet shape, and two reinforcing members 4 are respectively bonded to two ends of the insulating sheet 3 . The portion of the insulating sheet 3 bonded to the two reinforcing members 4 is two connecting portions 32 , and the remaining portion is an insulating body 31 .

[0053] It should be noted that since the insulating sheet 3 and the reinforcing member 4 are relatively thin, Figure 3From the perspective, the connection part 32 of the insulating sheet 3 and the reinforcing member 4 form a sheet-like structure. However, after the physical structure of the insulating sheet 3 and the physical structure of the reinforcing member 4 are bonded, the connection part 32 and the reinforcing member 4 are two stacked sheet-like structures.

[0054] During the manufacturing process of the battery cell, the insulating sheet 3 needs to be covered on the whole body consisting of the side plate 5, the electrode group 1 and the two cover plate assemblies 2, and the reinforcing member 4 is located on the side of the insulating sheet 3 facing away from the electrode group 1. Then, the hot melting point 7 is selected on the reinforcing member 4 for hot melting, so that the connecting portion 32 is hot-melted and connected with the plastic part 22, thereby realizing the connection between the plastic part 22 and the insulating sheet 3. Then, the whole body consisting of the insulating sheet 3, the side plate 5, the electrode group 1 and the two cover plate assemblies 2 is put into the shell, and finally the cover plate assembly 2 is welded to the shell 6, thereby completing the assembly process of the entire battery cell.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A battery cell, characterized in that: The battery cell comprises an electrode group, a cover plate assembly, an insulating sheet and a reinforcing member, wherein the electrode group is connected to the cover plate assembly, and the insulating sheet covers the electrode group; The insulating sheet includes an insulating body and a connecting portion, wherein the connecting portion is connected to one end of the insulating body in the length direction of the battery cell, the connecting portion includes a first fitting surface and a second fitting surface facing away from each other, the first fitting surface is fitted to the pole group, the reinforcement is connected to the second fitting surface, and the connecting portion is connected to the cover plate assembly.

2. The battery cell according to claim 1, characterized in that: An end of the reinforcement member in the length direction facing away from the insulation body is flush with an end of the connection portion facing away from the insulation body.

3. The battery cell according to claim 1, characterized in that: The cover plate assembly comprises a plate body and a plastic part, wherein one side of the plastic part in the length direction is in contact with the plate body, and the other side of the plastic part in the length direction is in contact with the pole group; The insulating sheet encloses a wrapping space, at least a portion of the plastic component is located inside the wrapping space, and the outer side wall of the plastic component in the length direction and / or width direction is connected to the connecting portion.

4. The battery cell according to claim 3, characterized in that: The dimension of the portion of the plastic part located inside the insulating sheet in the length direction is smaller than the dimension of the reinforcement part in the length direction.

5. The battery cell according to claim 4, characterized in that: The dimension of the reinforcement in the length direction is 15 mm to 25 mm.

6. The battery cell according to claim 3, characterized in that: The battery cell also includes a side plate, which is arranged inside the wrapping space, and includes a first connecting surface and a second connecting surface opposite to each other in the width direction of the battery cell, the first connecting surface is in contact with the electrode group, and the second connecting surface is in contact with the insulating sheet.

7. The battery cell according to claim 3, characterized in that: The battery core includes two reinforcing members, the insulating sheet includes two connecting parts, the two connecting parts are respectively connected to two ends of the insulating body in the length direction, and the two reinforcing members are respectively connected to the two connecting parts.

8. The battery cell according to claim 7, characterized in that: The battery cell includes two cover plate assemblies, which are respectively arranged on both sides of the pole group in the length direction, and the two connecting parts are respectively connected to the two cover plate assemblies.

9. The battery cell according to claim 8, characterized in that: The battery cell further comprises a shell, the insulating sheet and the pole group are both arranged inside the shell, the reinforcement is fitted with the shell, and the two cover plate assemblies are respectively connected to both ends of the shell in the length direction.

10. The battery cell according to any one of claims 1 to 9, characterized in that: The reinforcement member is an insulating member.

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