Battery and battery pack

Abstract

The utility model relates to the field of batteries, and discloses a battery and a battery pack. The battery comprises a battery cell, an electrode lead-out piece and an adhesive film, the battery cell is provided with a tab, and the tab and the electrode lead-out piece are welded to form a crator; one side, deviating from the electrode lead-out piece, of the tab is covered with the welding scar by the adhesive film, and at least part of the adhesive film corresponding to the welding scar is separated from the welding scar, so that an unbonded area is formed between the adhesive film and the welding scar. The battery can have high tab heat dissipation performance and high reliability of connection with the pole.

Description

Technical Field

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

[0002] In current commercial batteries, the tabs and terminal leads of battery cells are typically connected by welding. However, the weld scar formed after welding is located inside the casing after packaging. If the weld slag from the weld scar falls into the battery cell, it can cause a short circuit. To address this problem, tape is often placed over the weld scar to prevent the slag from falling. However, this weld location is used for overcurrent and generates a high amount of heat. The adhesion of the tape to the weld scar hinders heat dissipation from this location, making it more difficult to dissipate heat. Utility Model Content

[0003] The present application discloses a battery and a battery pack for improving the heat dissipation of a tab and the reliability of the connection with a pole.

[0004] To achieve the above objectives, this application provides the following technical solutions:

[0005] In a first aspect, the present application provides a battery comprising a battery cell, an electrode lead-out member and an adhesive covering film, wherein the battery cell is provided with a tab, the tab being welded to the electrode lead-out member to form a weld scar; the adhesive covering film covers the weld scar on the side of the tab facing away from the electrode lead-out member, and at least a portion of the adhesive covering film corresponding to the weld scar is separated from the weld scar to form an unbonded area between the adhesive covering film and the weld scar.

[0006] In the battery of this application, the welding process between the tab and the electrode lead forms a weld scar. To prevent slag from the weld scar from falling into the battery cell, an adhesive film is used to cover the weld scar. However, the adhesive film and the weld scar are at least partially separated, leaving an unbonded area between them. This creates a gap between the tab and the adhesive film, reducing heat transfer from the tab to the diaphragm, causing the diaphragm to heat up and shrink, leading to safety issues.

[0007] In a second aspect, the present application provides a battery pack, which includes a plurality of batteries of the present application, and the plurality of batteries are arranged along the width direction of the batteries.

[0008] The battery pack of the present application has the battery of the present application, and therefore, can have all the advantages of the first aspect of the present application, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 1 is a schematic structural diagram of a battery according to an embodiment;

[0010] Figure 2 This is a schematic diagram of the connection structure between the cover plate and the battery cell before being installed in the housing according to one embodiment;

[0011] Figure 3 Schematic diagram of the structure of a battery cell according to an embodiment;

[0012] Figure 4 This is a schematic diagram of the connection structure on the inner side of the cover of a battery according to an embodiment;

[0013] Figure 5 Schematic diagram of the connection structure between the electrode lead-out piece on the inner side of the cover and the tab;

[0014] Figure 6 Schematic diagram of the structure of an adapter sheet according to an embodiment.

[0015] Figure Number:

[0016] 10-shell; 20-cover; 21-pole; 211-positive pole; 212-negative pole; 22-adapter; 221-positive adapter; 222-negative adapter; 223-avoidance; 23-pressure relief mechanism; 30-battery cell; 31-battery cell body; 32-ear; 321-positive ear; 322-negative ear; 33-first part; 34-second part; 35-third part; 40-adhesive film; 50-weld scar. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0018] Figure 1 FIG. 1 is a schematic diagram of the exploded structure of a battery according to an embodiment of the present invention. Figure 1 As shown in FIG, the battery includes a cell, a shell 10 and a cover 20. For the convenience of description, Figure 1 The positions shown in define the length, width and height of the battery. Figure 1 The width direction of the battery is as shown in the x direction. Figure 1 The height direction of the battery is Figure 1 The z direction is shown. The length of the battery is consistent with the length of the cover. The width of the battery is consistent with the width of the cover. The height of the battery is consistent with the thickness of the cover.

[0019] Figure 2 FIG1 is a schematic diagram of the connection structure between the cover plate and the battery cell before being installed in the housing in an embodiment. Figure 2 As shown, each battery may include two cells. Figure 2The two battery cells of the shown connection structure are bent in a direction away from the cover when being installed in the housing, and then installed in the housing.

[0020] Figure 3 FIG. 1 is a schematic diagram of the structure of a battery cell according to an embodiment of the present invention. Figure 3 As shown, the battery cell 30 includes a battery cell body 31 and tabs 32 , wherein the tabs 32 are divided into a positive tab 321 and a negative tab 322 .

[0021] Reference Figure 3 Because the cell body 31 is composed of multiple alternating positive and negative electrode sheets and a separator, the tabs 32 can include multiple single-layer tab layers. For example, the positive tab can include multiple single-layer positive tab layers, and the negative tab can include multiple single-layer negative tab layers. The multiple single-layer positive tab layers in the positive tab can be connected by pressing or pre-welding. The multiple single-layer negative tab layers in the negative tab can also be connected by pressing or pre-welding.

[0022] Each tab 32 may include a first portion 33, a second portion 34, and a third portion 35. The second portion 34 is disposed between the first portion 33 and the third portion 35, thereby sequentially connecting the first portion 33, the second portion 34, and the third portion 35. The first portion 33 is connected to the cell body 31. The third portion 35 is connected to the electrode lead. Because the cell body 31 and the electrode lead are not in the same plane, the second portion 34, which serves as the connecting portion between the first portion 33 and the third portion 35, has a bend.

[0023] Figure 4 The figure is a schematic diagram of the connection structure on the inner side of the cover of a battery in an embodiment. Figure 4 The structure shown is Figure 3 The schematic structural diagram of the back side of the structure shown is a schematic structural diagram observed from the side of the cover plate facing the battery cell. Figure 5 This is a schematic diagram of the connection structure between the electrode lead-out piece on the inner side of the cover and the tab. Figures 2 to 5 The cover plate 20 is provided with an electrode lead-out part, such as a pole 21 or a combination of a pole 21 and a transition piece 22. The pole 21 is divided into a positive pole 211 and a negative pole 212. The transition piece 22 can be divided into a positive pole transition piece 221 and a negative pole transition piece 222. When the electrode lead-out part includes a transition piece 22, the transition piece can be first integrally formed with the cover plate and connected together. After the pole tab and the transition piece are welded, they are installed together into the shell, and then the cover plate and the shell are welded. During the assembly process, the pole tab will be bent to reduce the occupied space, so that there is a bent portion in the second part of the pole tab. The positive pole tab 321 of the battery cell is directly connected to the positive pole post 211, and the negative pole tab 322 is directly connected to the negative pole post 212. In addition, the positive pole tab 321 can also be connected to the positive pole post 211 through the positive pole transition piece 221, and the negative pole tab 322 can be connected to the negative pole post 212 through the negative pole transition piece 222.

[0024] like Figure 5 As shown, in this embodiment, the electrode lead-out member includes both a pole 21 and an adapter plate 22. The tab 32 is welded to the adapter plate 22. A weld scar 50 is formed at the welding point between the tab 32 and the adapter plate 22. The weld scar 50 represents the welding area between the tab and the electrode lead-out member. To prevent weld slag from the weld scar 50 from falling, the battery of the present application further includes an adhesive film 40. The adhesive film 40 covers the weld scar 50 on the side of the tab facing away from the electrode lead-out member, and the adhesive film 40 corresponding to the weld scar 50 is at least partially separated from the weld scar 50 to form an unbonded area between the adhesive film 40 and the weld scar 50. As a result, the weld scar 50 and the adhesive film 40 are at least partially separated to form a gap between them. The heat generated at the weld scar 50 can be dissipated using the gap as a heat dissipation space. The adhesive film corresponding to the weld scar is the portion of the adhesive film whose orthographic projection on the weld scar surface is located within the area enclosed by the edge of the weld scar.

[0025] In addition, the adhesive film 40 is separated from the weld scar 50, which can prevent the adhesive film 40 from generating a tearing force on the weld scar during the assembly of the battery cell, thereby improving the connection strength between the tab and the pole.

[0026] In addition, the heat generated at the weld scar position needs to pass through the gap and the adhesive film to reach the battery cell diaphragm. The heat transfer path is long because more heat can be dissipated through the electrode lead-out parts and the cover plate, avoiding excessive heat transfer to the battery cell diaphragm, causing the diaphragm to shrink and causing a short circuit between the positive and negative electrodes.

[0027] Figure 6 FIG. 1 is a schematic diagram of the structure of an adapter sheet according to an embodiment of the present invention. Figure 6 As shown, the adapter plate 22 can be a concave sheet structure with a bypass opening 223. The bypass opening 223 is used to avoid the liquid injection hole of the cover plate. When the adapter plate is far away from the liquid injection hole, the adapter plate can also be a rectangular sheet structure. In addition, the adapter plate can also be shaped like a Y-shaped structure.

[0028] Reference Figure 4 and Figure 5, each adapter 22 can connect the positive pole ears of two battery cells or can connect the negative pole ears of two battery cells. In this setting, each adapter 22 can form two corresponding weld scars 50. The two weld scars 50 can be arranged at intervals. Each weld scar 50 can be provided with a corresponding adhesive film 40. One end of each adhesive film 40 can be connected to the edge of the pole ear, such as bonding to part of the weld scar area or the non-weld scar area, and the other end can extend to the side of the battery cell body and bond to the side of the battery cell body. Among them, the battery cell body can be a rectangular structure, including four side faces and two end faces. Among the four side faces, there are two large faces and two small faces. The two large faces are arranged opposite to each other along the width direction of the battery cell. The two small faces are arranged opposite to each other along the length direction of the battery cell. The two end faces are arranged opposite to each other along the height direction of the battery cell. Among them, one end face is arranged on the cover plate side, and one end face is arranged on the side away from the cover plate. The adhesive film extends to the side of the battery cell body, which can reduce the risk of the tab being inserted back into the battery cell and short-circuiting with the different polarity pole pieces of the battery cell.

[0029] In one embodiment, the adhesive film 40 includes a base film, which is provided with an adhesive area 41 and a non-adhesive area 42. The adhesive area 41 of the base film is provided with an adhesive layer, while the non-adhesive area 42 of the base film is not provided with an adhesive layer. The weld scar 50 is at least partially covered by the non-adhesive area 42. In this arrangement, the adhesive film corresponding to the weld scar is not provided with an adhesive layer. In this way, the adhesive film is prevented from adhering to the weld scar, thereby preventing the adhesive film from exerting a tearing force on the tab.

[0030] In one embodiment, in the area corresponding to the weld scar, the ratio K of the area of ​​the non-bonded area to the area of ​​the weld scar satisfies 0.3-1.5. For example, the ratio of the area of ​​the non-bonded area to the area of ​​the weld scar can be, for example, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, or 1.5, or any value between any two of the above values. In the area corresponding to the weld scar, the ratio of the area of ​​the non-bonded area to the weld scar satisfies the above range, which can not only meet the heat dissipation requirements and increase heat dissipation, but also reduce the risk of welding slag falling.

[0031] In one embodiment, the non-bonding area completely covers the weld scar. When the weld scar is completely covered by the non-bonding area, heat dissipation at the weld scar can be maximized to avoid heat accumulation.

[0032] In one embodiment, the non-adhesive area of ​​the adhesive film covers the bent portion of the tab. The non-adhesive area covering the bent portion of the tab can prevent the adhesive film from pulling on the bent portion of the tab, reducing the risk of tearing the bent portion of the tab.

[0033] In one embodiment, the ratio k of the thickness of the adhesive layer to the thickness of the base film satisfies 0.05-0.3. Exemplarily, the ratio of the thickness of the adhesive layer to the thickness of the base film may be, for example, 0.05, 0.08, 0.1, 0.12, 0.15, 0.18, 0.2, 0.22, 0.25, 0.28 or 0.3 or a value between any two of the above values. When the ratio of the thickness of the adhesive layer to the thickness of the base film is too small, the gap between the adhesive film and the weld scar is too small, which is not conducive to heat dissipation. When the ratio of the two is too large, the welding slag falling from the weld scar is more likely to fall from the gap between the adhesive film and the weld scar, affecting the performance of the battery cell. Therefore, when the thickness of the adhesive layer and the thickness of the base film are controlled within the above range, it is not only conducive to heat dissipation, but also can play a good role in preventing welding slag from falling.

[0034] In one embodiment, the unbonded area between the adhesive film and the weld scar can extend along a certain direction to the edge of the adhesive film. At least one side of the unbonded area extends along a certain direction to the edge of the adhesive film, thereby forming a continuous heat dissipation channel along the direction of the unbonded area. Heat generated at the weld scar can be dissipated through the gap between the adhesive film and the weld scar, thereby preventing heat accumulation.

[0035] Continue to refer to Figure 4 In one embodiment, the non-adhesive area of ​​the adhesive film is provided along the length of the cover plate. At least one side of the non-adhesive area extends along the length of the cover plate to the edge of the adhesive film. When providing the adhesive area of ​​the adhesive film, all four sides of the weld scar can serve as the adhesive area. The adhesive area can be provided along the length of the cover plate, along the width of the cover plate, or at an angle. Providing the non-adhesive area along the length of the cover plate not only facilitates the production of the adhesive layer, but also allows the gap between the adhesive film and the weld scar to open toward the pressure relief vent of the cover plate, thereby allowing heat released from the gap to be discharged outward through the pressure relief vent. At least one side of the non-adhesive area extends along the length of the cover plate to the edge of the adhesive film. This effectively forms a complete heat dissipation channel along the length of the cover plate, allowing heat to dissipate through the heat dissipation channel. Furthermore, when a pressure relief mechanism is provided on the cover plate, heat can be transferred to the pressure relief mechanism. In the event of thermal runaway of the battery, heat can be quickly dissipated from the pressure relief mechanism.

[0036] In one embodiment, the adhesive film's bonding areas are positioned on both sides of the weld scar along the width of the cover plate. The gap formed in between can extend along the length of the cover plate to the edge of the adhesive film, facilitating heat dissipation. Furthermore, providing bonding areas on both sides of the weld scar further reduces the risk of weld slag droplets. Alternatively, the bonding area can be positioned only on one side of the weld scar, i.e., on the side of the tab closest to the midline of the cover plate's length.

[0037] In one embodiment, the ratio K2 of the unconnected area S1, where the adhesive film separates the tab, to the total tab thickness D is within a range of 0.001-0.5. The total tab thickness D = the thickness of a single tab layer * the total number of tab layers. Thinner tabs have lower current flow capacity and generate more heat, requiring a larger unconnected area. Keeping the ratio within this range ensures that the heat dissipation area can meet heat dissipation requirements and prevents heat accumulation.

[0038] Based on the same technical purpose, an embodiment of the present application also provides a battery pack. This battery pack includes multiple batteries of the present application and may also include a busbar. The multiple batteries are arranged along the width of the battery, which is the direction perpendicular to the large surface of the battery. The busbar connects the poles of different batteries, achieving series and parallel connection between the multiple batteries.

[0039] Obviously, those skilled in the art may make various changes and modifications to the embodiments of the present application without departing from the spirit and scope of the present application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations.

Claims

1. A battery, characterized in that: The battery comprises a battery cell, an electrode lead-out piece and an adhesive film, wherein the battery cell is provided with a tab, and the tab is welded to the electrode lead-out piece to form a weld scar; The adhesive film covers the weld scar on the side of the tab away from the electrode lead-out piece, and the adhesive film corresponding to the weld scar is at least partially separated from the weld scar to form an unbonded area between the adhesive film and the weld scar.

2. The battery according to claim 1, characterized in that The adhesive covering film includes a base film, the base film is provided with a bonding area and a non-bonding area, the bonding area surface of the base film is provided with a bonding layer, the non-bonding area surface of the base film is not provided with the bonding layer, and at least part of the non-bonding area covers the weld scar.

3. The battery according to claim 2, characterized in that In the area corresponding to the weld scar, a ratio K of the area of ​​the non-bonding zone to the area of ​​the weld scar satisfies 0.3-1.

5.

4. The battery according to claim 2, characterized in that The non-bonded area completely covers the weld scar.

5. The battery according to claim 2, characterized in that The tab includes a first part, a second part and a third part, the second part is arranged between the first part and the third part, the first part is connected to the body of the battery cell, the third part is connected to the electrode lead-out piece, the second part has a bending portion, and the non-adhesive area of ​​the adhesive film covers the bending portion of the tab.

6. The battery according to claim 2, characterized in that The ratio k of the thickness of the adhesive layer to the thickness of the base film satisfies 0.05-0.

3.

7. The battery according to claim 2, characterized in that The battery further includes a cover plate, the electrode lead-out member is connected to the cover plate, the non-adhesive area of ​​the adhesive film is arranged along the length direction of the cover plate, and at least one side of the non-adhesive area extends along the length direction of the cover plate to the edge of the adhesive film.

8. The battery according to claim 7, characterized in that The bonding areas of the adhesive film are arranged on both sides of the weld scar along the width direction of the cover plate.

9. The battery according to any one of claims 2 to 8, characterized in that: The ratio K2 of the area S1 of the non-bonding region to the total thickness D of the tab satisfies 0.001-0.5; wherein the total thickness D of the tab = the thickness of a single-layer tab * the total number of tab layers.

10. A battery pack, characterized in that: The invention comprises a plurality of batteries according to any one of claims 1 to 9, wherein the plurality of batteries are arranged along the width direction of the battery.

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