Secondary battery

Abstract

The application provides a secondary battery, comprising: a shell, one side of the shell being provided with an opening; an electric core, the electric core being located in the shell; a cover plate assembly, the cover plate assembly being arranged on the opening side of the shell to close the opening, the cover plate assembly comprising a cover plate, an insulating film and a lower plastic connected to the side of the cover plate facing the electric core, the insulating film comprising a connecting part and wrapping parts oppositely connected to the two sides of the connecting part, the connecting part being arranged between the cover plate and the lower plastic, the connecting part covering the top surface of the electric core, and the wrapping parts wrapping the outer surface of the electric core. The secondary battery provided by the application can reduce the hot melting process, avoid the welding slag from entering the inside of the electric core and improve the safety performance of the battery.

Description

Technical Field

[0001] This utility model relates to the field of battery manufacturing technology, specifically to a secondary battery. Background Technology

[0002] The main components of a square battery are electrodes, separator, cover plate, insulating film, connecting piece, base plate, electrolyte, and casing. The existing assembly and manufacturing process involves: electrodes and separator forming the cell; the cell being welded to the cover plate via connecting pieces; an insulating film covering the bottom and sides of the cell; the top edge of the insulating film being fixed to the cover plate via heat fusion; after heat fusion welding, the cell being inserted into the casing containing the base plate; and finally, the cover plate being sealed to the top of the casing by welding. Because the top of the insulating film has an opening, and the top of the insulating film is only fixed to the cover plate via a few heat fusion welds, weld slag can easily enter the cell from the un-heat fused areas between the insulating film and the cover plate during the sealing weld of the cover plate and casing. This reduces the cell's safety performance and could lead to accidents. Utility Model Content

[0003] In order to overcome the defects in the prior art, this utility model provides a secondary battery that can reduce the hot-melting process, prevent welding slag from entering the cell, and improve the safety performance of the battery.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0005] This utility model discloses a secondary battery, comprising:

[0006] A housing, wherein an opening is provided on one side;

[0007] The battery cell is located inside the housing;

[0008] A cover plate assembly is disposed on the opening side of the housing to close the opening. The cover plate assembly includes a cover plate, an insulating film, and a lower plastic film connected to the cover plate on the side facing the battery cell. The insulating film includes a connecting portion and wrapping portions connected to both sides of the connecting portion. The connecting portion is disposed between the cover plate and the lower plastic film. The connecting portion covers the top surface of the battery cell, and the wrapping portions wrap around the outer surface of the battery cell.

[0009] The above technical solution uses a cover plate and lower plastic to fix the insulating film, which reduces the hot-melting process of the insulating film and lowers the battery defect rate caused by hot melting. Due to the position setting of the insulating film, the wrapping direction of the insulating film is changed to wrap the battery cell from the top to the bottom. There is no gap between the top of the insulating film and the top of the battery cell, which can prevent foreign objects such as welding slag from entering the battery cell during the welding of the cover plate and improve the safety performance of the battery cell.

[0010] Furthermore, the packaging section includes a main packaging area, a bottom packaging area connected to the main packaging area, and two side packaging areas. The top edge of the main packaging area is connected to the long side of the connecting section, the bottom edge is connected to the long side of the bottom packaging area, and the two side edges are respectively connected to the long sides of the two side packaging areas.

[0011] This application improves the covering effect of the battery cell by setting wrapping parts on both sides of the connecting part to jointly wrap the battery cell. The structure of the wrapping part allows the wrapping part to wrap the bottom, sides and main surface of the battery cell separately, eliminating the need to set a bottom support plate at the bottom of the housing, thereby improving assembly efficiency and saving assembly materials.

[0012] Furthermore, the length direction of the main packaging area corresponds to the height direction of the battery cell, the width direction of the main packaging area corresponds to the length direction of the cover plate, the length of the main packaging area is greater than the height of the battery cell, and the width of the main packaging area is less than the length of the cover plate.

[0013] After the insulating film wraps the battery cell, it needs to be installed into the housing. If the width of the main wrapping area is equal to or greater than the length of the cover plate, it is easy to cause poor assembly. If the length of the main wrapping area is less than or equal to the height of the battery cell, the battery cell cannot be completely wrapped.

[0014] Furthermore, the difference between the length of the main wrapping area and the height of the battery cell is less than or equal to 5mm. If the length of the main wrapping area is too long, the insulating film will occupy a large space, reducing the battery's energy density. When the length of the main wrapping area is slightly greater than the height of the battery cell, the wrapping effect is optimal.

[0015] Furthermore, the difference between the width of the main wrapping area and the length of the cover plate is 1 to 5 mm. If the width of the main wrapping area is too small, it will be impossible to completely wrap the battery cell or the battery cell volume will need to be reduced, resulting in more processing steps.

[0016] Furthermore, the width of the bottom wrapping area and the two side wrapping areas is greater than 0.5 times the total thickness of the battery cell wrapped by the insulating film. This results in an overlapping area at the bottom of the two wrapping portions on both sides of the battery cell, allowing the insulating film to completely wrap the battery cell.

[0017] Furthermore, the connecting part is provided with a through hole. The cover plate is provided with a terminal post, a liquid injection hole, and an explosion-proof valve. The position of the through hole corresponds to the position of the terminal post, the liquid injection hole, and the explosion-proof valve to avoid affecting the assembly of the battery.

[0018] Furthermore, adhesive is provided on the side of the connecting part that contacts the lower plastic. The connecting part is fixed to the lower plastic by the adhesive, ensuring the firmness of the connecting part between the battery cell and the lower plastic.

[0019] Furthermore, the thickness of the insulating film is 0.1–0.5 mm. The insulating film is used to wrap the battery cell. If the thickness is too small, the strength of the insulating film will decrease, making it easy to cause damage during assembly and reducing the protective performance of the battery cell. If the thickness is too large, it will occupy a lot of space, thereby reducing the energy density of the battery.

[0020] Furthermore, adhesive is applied to the bottom wrapping area and the two side wrapping areas. The adhesive can fix the wrapping portion on the outer surface of the battery cell, ensuring the firmness of the insulating film wrapping the battery cell.

[0021] Due to the application of the above technical solution, this utility model has the following advantages compared with the prior art:

[0022] 1. This application uses a cover plate and lower plastic to fix the insulating film, which reduces the hot-melting process of the insulating film and lowers the battery defect rate caused by hot melting. Due to the position setting of the insulating film, the wrapping direction of the insulating film is changed to wrap the battery cell from the top to the bottom of the battery cell. There is no gap between the top of the insulating film and the top of the battery cell, which can prevent foreign objects such as welding slag and dust from entering the battery cell during the welding of the cover plate, thereby improving the safety performance of the battery cell.

[0023] 2. This application wraps the bottom of the battery cell with the bottom wrapping area of ​​the insulating film, eliminating the need for a bottom support plate at the bottom of the casing, which can improve assembly efficiency and save assembly materials.

[0024] To make the above and other objects, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a connection diagram of a cover plate assembly and a battery cell provided in an embodiment of this application;

[0027] Figure 2 This is a structural diagram of an insulating film provided in an embodiment of this application;

[0028] Figure 3 This is a partial view of a cover plate assembly provided in an embodiment of this application;

[0029] Figure 4 This is a structural diagram of a secondary battery provided in an embodiment of this application.

[0030] The reference numerals in the above figures are as follows: 1. Housing; 2. Battery cell; 3. Cover plate; 4. Lower plastic; 5. Connecting part; 6. Main wrapping area; 7. Bottom wrapping area; 8. Side wrapping area. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. In addition, the accompanying drawings of the present invention are only simple schematic illustrations and are not depictions based on actual dimensions, as stated in advance.

[0032] In this utility model, it should be noted that the terms "upper," "lower," "inner," "outer," "forward," "backward," "between," "nearer," and "farthest" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing this utility model and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. It should also be noted that, unless otherwise explicitly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0033] It should be understood that while terms such as "first," "second," and "third" may be used in this document to describe various components or signals, these components or signals should not be limited by these terms. These terms are primarily used to distinguish one component from another, or one signal from another. Furthermore, the term "or" as used herein should, as appropriate, include any combination of one or more of the related listed items.

[0034] Reference Figures 1-4 This application provides a secondary battery, which is a square battery, comprising:

[0035] The housing 1 has an opening on one side and is used to provide space for housing the internal components of the battery.

[0036] Battery cell 2 is located inside housing 1 and has tabs on it.

[0037] A cover plate assembly is provided on the opening side of the housing 1 to close the opening. The cover plate assembly includes a cover plate 3, an insulating film, and a lower plastic 4 connected to the cover plate 3 facing the battery cell 2. The cover plate 3 is connected to the housing 1 and is located at the top opening of the housing 1 to seal the housing 1. The cover plate 3 is provided with an electrode post, a liquid injection hole, and an explosion-proof valve. The lower plastic 4 is fixed to the side of the cover plate 3 facing the battery cell 2 by connecting to the electrode post. The connection and fixing method between the lower plastic 4 and the electrode post is the same as the existing method, and will not be described in detail here. The insulating film includes a connecting part 5 and wrapping parts connected to both sides of the connecting part 5. The connecting part 5 is located between the cover plate 3 and the lower plastic 4. The connecting part 5 covers the top surface of the battery cell 2. After the electrode tabs on the battery cell 2 are connected to the cover plate 3 through an adapter piece, the wrapping parts wrap around the outer surface of the battery cell 2.

[0038] With the above structure, the secondary battery in this application embodiment can reduce the hot melting process of the insulating film, reduce the battery defect rate caused by hot melting, and prevent foreign objects such as welding slag and dust from entering the cell during cover welding, thereby improving the safety performance of the cell.

[0039] Specifically, such as Figure 2 and Figure 3 As shown, the connecting part 5 is provided with multiple through holes. The size, number and shape of the multiple through holes are flexibly set according to the size, number and shape of the pole, injection hole and explosion-proof valve on the cover plate 3.

[0040] To enhance the firmness of the connecting part 5 between the cover plate 3 and the lower plastic 4, in the embodiments of this application, an adhesive is provided on the side of the connecting part 5 that contacts the lower plastic 4. The adhesive can be an existing glue, such as a 1% NMP solution of polyvinylidene fluoride.

[0041] It should be noted that the shape and size of the connecting part 5 can be flexibly set according to the shape, number and size of the battery cell, as long as the overall area of ​​the connecting part 5 can completely cover the top surface of the battery cell 2.

[0042] like Figures 1-4 As shown in the illustration, this application takes a square battery with a square cell inside as an example. The cell is rectangular in shape, the cover is rectangular, and the connecting part 5 is rectangular, with the long side of the connecting part 5 corresponding to the long side of the cover. In other possible embodiments, the housing 1 may contain multiple cells. The connection between the multiple cells can be in series, in parallel, or partially in series and partially in parallel, which will not be specifically described here.

[0043] like Figure 1 and Figure 4As shown, the battery cell 2 has two side surfaces along the first direction, which are spaced apart along the first direction. The battery cell 2 also has two main surfaces along the second direction, which are spaced apart along the second direction. The surface area of ​​the main surfaces is larger than that of the side surfaces; that is, the main surfaces correspond to the larger surface area of ​​the battery (casing). It can be understood that when the battery is placed vertically with the cover facing upwards, the first direction corresponds to the thickness (width) direction of the battery cell (casing), the second direction corresponds to the length direction of the battery cell (casing / cover), and the vertical direction corresponds to the height direction of the battery cell (casing).

[0044] The wrapping section includes a main wrapping area 6, a bottom wrapping area 7 connected to the main wrapping area 6, and two side wrapping areas 8. The main wrapping area 6 is rectangular in shape. The top edge of the main wrapping area 6 is connected to the long side of the connecting part 5, the bottom edge is connected to the long side of the bottom wrapping area 7, and the two side edges are connected to the long sides of the two side wrapping areas 8 respectively. The main wrapping area 6 completely wraps the main surface of the battery cell 2, the bottom wrapping area 7 wraps the bottom surface of the battery cell 2, and the two side wrapping areas 8 wrap the two sides of the battery cell 2.

[0045] like Figure 2 As shown in the embodiments of this application, the main wrapping area 6 and the bottom wrapping area 7 are an integral structure, and the main wrapping area 6 and the two side wrapping areas 8 are an integral structure. The connecting part 5 of the insulating film and the two wrapping parts are an integral structure.

[0046] The length of the main wrapping area 6 corresponds to the height of the battery cell 2, the width of the main wrapping area 6 corresponds to the length of the cover plate 3, the top edge of the main wrapping area 6 is equal to the length of the connecting part 5, the bottom edge is equal to the length of the bottom wrapping area 7, and the two side edges are equal to the length of the two side wrapping areas 8 respectively.

[0047] In order to fit the battery cell 2 into the housing 1 and to improve the wrapping effect of the insulating film around the battery cell 2, the width of the main wrapping area 6 is less than the length of the cover plate 3, and the length of the main wrapping area 6 is greater than the height of the battery cell 2.

[0048] In the embodiments of this application, the difference between the length of the main packaging area 6 and the height of the battery cell 2 is less than or equal to 5 mm, and the difference between the width of the main packaging area 6 and the length of the cover plate 3 is 1 to 5 mm.

[0049] In order to completely wrap the battery cell, the width of the bottom wrapping area 7 and the two side wrapping areas 7 is greater than 0.5 times the total thickness of the battery cell wrapped by the insulating film. This results in an overlap between the bottom wrapping area 7 and the two side wrapping areas 7 of one wrapping area and the bottom wrapping area 7 and the two side wrapping areas 7 of the other wrapping area when the two wrapping areas on both sides of the connecting part 5 jointly wrap the battery cell.

[0050] It should be noted that the two wrapping parts set on both sides of the connecting part 5 can be symmetrically set or asymmetrically set, as long as the two wrapping parts can cover the battery cell together.

[0051] To enhance the secure wrapping of the battery cell 2, adhesive tape is provided on the bottom wrapping area 7 and the two side wrapping areas 8. Optionally, the adhesive tape can be directly applied to the outer surface of the wrapping area, and the size, position, and quantity of the adhesive tape can be flexibly set.

[0052] In the embodiments of this application, the thickness of the insulating film is 0.1 to 0.5 mm, so that the insulating film meets the requirements for covering the battery cell while avoiding excessive thickness that would waste space inside the battery casing.

[0053] In one possible embodiment, the insulating film is made of an insulating material with certain thermal conductivity, such as PI or PET, to ensure the insulating effect of the insulating film while avoiding the reaction between the insulating film and the electrolyte.

[0054] The process of connecting the cover plate assembly and the battery structure in the above embodiment is as follows: according to the existing process, the positive and negative electrode materials are made into positive and negative slurries in a certain proportion. The positive and negative electrode slurries are evenly coated on aluminum foil and copper foil. The solvent is removed by passing through a tunnel oven to make coated positive and negative electrode sheets. After rolling, die cutting and other processes, positive and negative electrode sheets are made. The positive electrode sheets, separator and negative electrode sheets are made into battery cells by winding or stacking. After welding the battery cells and cover plate assembly together with connecting pieces, the wrapping part is bent to wrap the battery cells. Then, the battery cells wrapped with insulating film are assembled into the shell, laser welded, injected with liquid, and formed according to the existing process to complete the battery manufacturing.

[0055] This utility model uses specific embodiments to illustrate the principle and implementation of the utility model. The above description of the embodiments is only for the purpose of helping to understand the method and core idea of ​​the utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the utility model. Therefore, the content of this specification should not be construed as a limitation of the utility model.

Claims

1. A secondary battery, characterized in that, include: A housing, wherein an opening is provided on one side; The battery cell is located inside the housing; A cover plate assembly is disposed on the opening side of the housing to close the opening. The cover plate assembly includes a cover plate, an insulating film, and a lower plastic film connected to the cover plate on the side facing the battery cell. The insulating film includes a connecting portion and wrapping portions connected to both sides of the connecting portion. The connecting portion is disposed between the cover plate and the lower plastic film. The connecting portion covers the top surface of the battery cell, and the wrapping portions wrap around the outer surface of the battery cell.

2. A secondary battery according to claim 1, characterized in that, The packaging section includes a main packaging area, a bottom packaging area connected to the main packaging area, and two side packaging areas. The top edge of the main packaging area is connected to the long side of the connecting section, the bottom edge is connected to the long side of the bottom packaging area, and the two side edges are respectively connected to the long sides of the two side packaging areas.

3. A secondary battery according to claim 2, characterized in that, The length of the main packaging area corresponds to the height of the battery cell, and the width of the main packaging area corresponds to the length of the cover plate. The length of the main packaging area is greater than the height of the battery cell, and the width of the main packaging area is less than the length of the cover plate.

4. A secondary battery according to claim 3, characterized in that, The difference between the length of the main packaging area and the height of the battery cell is less than or equal to 5 mm.

5. A secondary battery according to claim 3, characterized in that, The difference between the width of the main packaging area and the length of the cover plate is 1 to 5 mm.

6. A secondary battery according to claim 2, characterized in that, The width of the bottom wrapping area and the two side wrapping areas is greater than 0.5 times the total thickness of the battery cell wrapped by the insulating film.

7. A secondary battery according to claim 1, characterized in that, The connecting part is provided with a through hole.

8. A secondary battery according to claim 1, characterized in that, The side of the connecting part that contacts the lower plastic is provided with adhesive.

9. A secondary battery according to claim 1, characterized in that, The thickness of the insulating film is 0.1 to 0.5 mm.

10. A secondary battery according to claim 2, characterized in that, Adhesive is applied to the bottom wrapping area and the two side wrapping areas.

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