Cell, battery module and manufacturing method of cell

Abstract

The present invention relates to the technical field of batteries, and discloses a battery cell, a battery module and a manufacturing method of the battery cell. The battery cell includes an aluminum shell, a core package and a negative connection piece. Negative top covers and positive top covers are respectively connected to two opposite ends of the aluminum shell. The negative top cover includes a negative top cover body and a negative terminal, and the positive top cover includes a positive top cover body and a positive terminal. Positive electrode tabs and negative electrode tabs respectively extend from two opposite sides of the core package in the width direction. The positive electrode tab is electrically connected to the positive terminal; the negative connection piece is connected to the negative electrode tab by roll welding, and one end of the negative connection piece is connected to the negative terminal, forming an overall conductive path, enabling the battery cell to achieve charge and discharge functions. In addition, the negative connection piece is connected to the negative electrode tab by roll welding. This welding process can improve the overcurrent capacity of the welding position between the negative electrode tab and the negative connection piece, and can also make the deformation of the negative electrode tab smaller, with good welding flatness and high welding efficiency, which is beneficial to the assembly of the battery cell.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a battery cell, a battery module, and a method for manufacturing a battery cell. Background Art

[0002] In the prior art, ultrasonic welding is usually used for the tab of a square battery and a connecting piece with a flat welding head and a flat welding seat. This method has the following defects:

[0003] (1) The tab of a square battery is generally relatively long, and this welding method is not suitable for welding the long-side tab, and S-shaped welding deformation is likely to occur.

[0004] (2) Only one weld mark is formed on the tab by this welding method, and the size of the weld mark is small, resulting in poor current-carrying capacity at the welding position of the tab and the connecting piece.

[0005] Therefore, there is an urgent need to provide a battery cell, a battery module, and a method for manufacturing a battery cell to solve the above problems. Summary of the Invention

[0006] According to the first object of the present invention, the present invention aims to provide a battery cell, which can make the deformation of the negative tab smaller, has good welding flatness, and is beneficial to the assembly of the battery cell.

[0007] To achieve the above object, the present invention is realized by the following technical solutions:

[0008] A battery cell, comprising:

[0009] An aluminum shell, with a negative top cover and a positive top cover respectively connected to its opposite ends. The negative top cover includes a negative top cover body and a negative terminal insulatedly arranged on the negative top cover body. The positive top cover includes a positive top cover body and a positive terminal arranged on the positive top cover body;

[0010] A core package, accommodated in the aluminum shell. Positive and negative tabs respectively extend from opposite sides of the core package in the width direction. The positive tab is electrically connected to the positive terminal;

[0011] A negative connecting piece, located in the aluminum shell. The negative connecting piece is connected to the negative tab by roll welding, and one end of the negative connecting piece is electrically connected to the negative terminal.

[0012] As a preferred solution, a plurality of weld marks are formed on the negative tab at intervals along the length direction of the negative tab.

[0013] As a preferred solution, the distance between adjacent two weld marks is greater than 5 mm.

[0014] As a preferred solution, a continuous whole-section weld mark is formed on the negative tab.

[0015] As a preferred solution, after the negative electrode tab and the negative electrode connecting piece are stacked, they are located between the upper rolling welding roller and the lower rolling welding roller. The diameters of the upper rolling welding roller and the lower rolling welding roller are equal, and the length of the welding mark is greater than the circumference of the upper rolling welding roller or the lower rolling welding roller.

[0016] As a preferred solution, the minimum distance between the centers of the upper rolling welding roller and the lower rolling welding roller along the length direction of the negative electrode tab is greater than or equal to zero, and the maximum distance is less than the radius of the upper rolling welding roller or the lower rolling welding roller.

[0017] As a preferred solution, the positive electrode tab is connected to one side of the aluminum shell by laser welding, and the aluminum shell is electrically connected to the positive terminal.

[0018] As a preferred solution, it further includes a positive electrode connecting piece. The positive electrode connecting piece is located inside the aluminum shell, and the positive electrode connecting piece is connected to the positive electrode tab by rolling welding, and the positive electrode connecting piece is electrically connected to the positive terminal.

[0019] According to the second object of the present invention, the present invention aims to provide a battery module, which can improve the assembly efficiency by applying the above-mentioned battery cell.

[0020] To achieve the above object, the present invention is realized by the following technical solutions:

[0021] The battery module includes a battery box and also includes the battery cell described in any one of the above, and the battery cell is accommodated in the battery box.

[0022] According to the third object of the present invention, the present invention aims to provide a method for manufacturing a battery cell, which can make the deformation of the negative electrode tab smaller, the welding flatness better, the welding efficiency higher, and is beneficial to the assembly of the battery cell.

[0023] To achieve the above object, the present invention is realized by the following technical solutions:

[0024] The method for manufacturing a battery cell is used to manufacture the battery cell described in any one of the above. The method for manufacturing the battery cell includes:

[0025] Step S1: Form the core package by using the stacking or winding method, and make the positive electrode tab and the negative electrode tab located on both sides of the core package along the width direction;

[0026] Step S2: Connect the negative electrode tab and the negative electrode connecting piece by rolling welding, and weld the extended end to the negative terminal.

[0027] Step S3: Weld and connect the positive electrode tab to the conductive component so that the positive electrode tab and the positive terminal are electrically connected through the conductive component.

[0028] As a preferred solution, step S3 specifically includes:

[0029] Step S31: Place the core package and the negative connection piece into the aluminum shell;

[0030] Step S32: Weld and connect the positive electrode tab to one side of the aluminum shell by laser welding.

[0031] As a preferred solution, step S3 specifically includes:

[0032] Step S31: Connect the positive electrode tab and the positive connection piece by roll welding;

[0033] Step S32: Place the core package, the negative connection piece, and the positive connection piece into the aluminum shell, and weld and connect the positive connection piece to the positive terminal.

[0034] As a preferred solution, the method for manufacturing the battery cell further includes:

[0035] Step S4: Weld the negative top cover and the positive top cover to both ends of the aluminum shell respectively to encapsulate the aluminum shell.

[0036] The beneficial effects of the present invention are as follows:

[0037] For the battery cell provided by the present invention, the positive electrode tab and the negative electrode tab are respectively arranged on both sides of the core package along the width direction. Compared with the prior art in which the positive electrode tab and the negative electrode tab are arranged at both ends of the core package along the length direction, it can shorten the conduction path, reduce the impedance of the battery cell, and thus improve the power performance of the battery cell, thereby enhancing the fast charging performance of the battery cell. The positive electrode tab is electrically connected to the positive top cover, and the negative electrode tab is electrically connected to the negative top cover through the negative connection piece, forming an overall conductive path, enabling the battery cell to complete the charge and discharge functions. Among them, the negative connection piece and the negative electrode tab are connected by roll welding. This welding process can improve the current-carrying capacity at the welding position between the negative electrode tab and the negative connection piece, and can also make the deformation of the negative electrode tab smaller, with good welding flatness, which is beneficial to the assembly of the battery cell.

[0038] For the battery module provided by the present invention, by applying the above battery cell, the overall performance of the battery module can be improved, and the assembly efficiency can be increased.

[0039] For the method for manufacturing the battery cell provided by the present invention, by connecting the negative connection piece and the negative electrode tab by roll welding, the current-carrying capacity at the welding position between the negative electrode tab and the negative connection piece can be improved, and the deformation of the negative electrode tab can also be made smaller, with good welding flatness, which is beneficial to the assembly of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly and understandably illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. The following described drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0041] Figure 1 is an exploded view of the battery cell provided in Embodiment 1 of the present invention;

[0042] Figure 2 is a schematic diagram of the overall structure of the battery cell provided in Embodiment 1 of the present invention;

[0043] Figure 3 is a schematic diagram of the structure of the battery cell provided in Embodiment 1 of the present invention after removing the insulating film;

[0044] Figure 4 is a schematic diagram of the roll welding of the negative electrode tab and the negative electrode connecting piece provided in Embodiment 1 of the present invention;

[0045] Figure 5 is an exploded view of the roll welding of the negative electrode tab and the negative electrode connecting piece provided in Embodiment 1 of the present invention;

[0046] Figure 6 is a schematic diagram of the welding mark on the negative electrode tab provided in Embodiment 1 of the present invention;

[0047] Figure 7 is a front view of the roll welding of the negative electrode tab and the negative electrode connecting piece provided in Embodiment 1 of the present invention;

[0048] Figure 8 is a specific flowchart of the manufacturing method of the battery cell provided in Embodiment 1 of the present invention;

[0049] Figure 9 is a schematic diagram of the welding mark on the negative electrode tab provided in Embodiment 2 of the present invention;

[0050] Figure 10 is a specific flowchart of the manufacturing method of the battery cell provided in Embodiment 3 of the present invention.

[0051] In the figure:

[0052] 100, upper roll welding roller; 200, lower roll welding roller;

[0053] 1, aluminum shell; 11, positive electrode top cover; 12, negative electrode top cover; 121, negative electrode top cover body; 122, negative terminal;

[0054] 2, core package; 21, positive electrode tab; 22, negative electrode tab; 221, welding mark;

[0055] 3. Negative connection piece

[0056] 4. Inner protective film; 41. Notch

[0057] 5. Insulating sheet

[0058] 6. Insulating film Specific implementation manner

[0059] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. In addition, it should be noted that for the sake of description, only the parts related to the present invention rather than all the structures are shown in the accompanying drawings.

[0060] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0061] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "over" and "on" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "under" and "beneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is lower than that of the second feature.

[0062] In the description of this embodiment, the orientation or positional relationships such as "above", "below", "left", and "right" are based on the orientation or positional relationships shown in the accompanying drawings. It is only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention. In addition, the terms "first" and "second" are only used for distinction in description and have no special meanings.

[0063] Embodiment 1

[0064] This embodiment provides a battery module. Multiple battery modules can form a battery pack, which can be applied to new energy vehicles to store and release energy and provide power for new energy vehicles. The battery module includes a battery box and multiple battery cells, and the multiple battery cells are accommodated in the battery box. Among them, the battery cells are square battery cells.

[0065] Specifically, as Figure 1 and Figure 3 shown, the battery cell provided in this embodiment includes an aluminum shell 1, a core package 2, and a negative connection piece 3. Negative top covers 12 and positive top covers 11 are respectively welded to opposite ends of the aluminum shell 1 along the length direction. Specifically, the negative top cover 12 includes a negative top cover body 121 and a negative terminal 122. The negative top cover body 121 is buckled and welded to one end of the aluminum shell 1, and the negative terminal 122 penetrates and is insulated on the negative top cover body 121 to serve as the negative output terminal. Similarly, the positive top cover 11 includes a positive top cover body and a positive terminal (not shown in the figure). The positive top cover body is buckled and welded to the other end of the aluminum shell 1, and the positive terminal is arranged on the positive top cover body and is electrically connected to the positive top cover body to serve as the positive output terminal.

[0066] Furthermore, the core package 2 is accommodated in the aluminum shell 1. Positive electrode tabs 21 and negative electrode tabs 22 respectively extend from opposite sides of the core package 2 along the width direction. The positive electrode tab 21 is in contact connection with one side of the aluminum shell 1, and the aluminum shell 1 is electrically connected to the positive top cover body, and thus is electrically connected to the positive terminal to achieve positive output; the negative connection piece 3 is located in the aluminum shell 1 and is insulated from the aluminum shell 1. The negative connection piece 3 is bent, one end is connected to the negative electrode tab 22 by roll welding, and the other end is electrically connected to the negative terminal 122 to achieve negative output, forming an overall conductive path, so that the battery cell can complete the charging and discharging functions.

[0067] For the battery cell provided in this embodiment, the length of the core package 2 is greater than the width of the core package 2. The positive electrode tab 21 and the negative electrode tab 22 are respectively arranged on opposite sides of the core package 2 along the width direction. Compared with the prior art in which the positive electrode tab 21 and the negative electrode tab 22 are respectively arranged at opposite ends of the core package 2 along the length direction, the conductive path can be shortened, the impedance of the battery cell can be reduced, and thus the power performance of the battery cell can be improved, thereby enhancing the fast charging performance of the battery cell. Secondly, the positive electrode tab 21 is directly in contact connection with the aluminum shell 1, so that the aluminum shell 1 serves as a positive connection piece to be connected to the positive top cover 11 to form a conductive path, eliminating the setting of the positive connection piece, simplifying the structure, reducing the cost, and improving the grouping efficiency. In addition, the roll welding process adopts the principle of resistance welding, which can improve the overcurrent capacity of the welding position between the negative electrode tab 22 and the negative connection piece 3, and can also make the deformation of the negative electrode tab 22 smaller, with good welding flatness and high welding efficiency, which is beneficial to the subsequent assembly of the battery cell.

[0068] As a preferred solution, the positive electrode tab 21 is connected to the aluminum case 1 by laser welding. During welding, it can be directly welded outside the aluminum case 1, which is convenient to operate, has good connection performance, high production efficiency and low cost.

[0069] It can be understood that the positive electrode tab 21 is made of aluminum, the negative electrode tab 22 is made of copper, and the aluminum case 1 is also made of aluminum. Therefore, the positive electrode tab 21 and the aluminum case 1 are of the same metal, and the welding is relatively easy and the welding effect is good. While the negative electrode tab 22 and the aluminum case 1 are of dissimilar metals, the welding is relatively difficult and the welding effect is not good. Therefore, in order to meet the connection requirements and facilitate operation, only the positive electrode tab 21 needs to be welded to the aluminum case 1.

[0070] It should be noted that, as Figure 4 and Figure 5 shown, the negative electrode tab 22 and the negative connection piece 3 are welded by a roll welding device. The roll welding device includes an upper roll welding wheel 100 and a lower roll welding wheel 200. The diameters of the upper roll welding wheel 100 and the lower roll welding wheel 200 are equal. After the negative electrode tab 22 and the negative connection piece 3 are stacked, they are placed between the upper roll welding wheel 100 and the lower roll welding wheel 200. The upper roll welding wheel 100 and the lower roll welding wheel 200 press the negative electrode tab 22 and the negative connection piece 3 and then pass an electric current to perform rolling welding.

[0071] Furthermore, as Figure 6 shown, the roll welding process can meet the design requirements of multi-segment intermittent short welding marks. That is, through roll welding, multiple welding marks 221 can be formed on the negative electrode tab 22 at intervals along the length direction of the negative electrode tab 22 to improve the connection effect between the negative electrode tab 22 and the negative connection piece 3, thereby enhancing the current-carrying capacity at the welding position between the negative electrode tab 22 and the negative connection piece 3. Preferably, the distance between adjacent two welding marks 221 is greater than 5 mm. Exemplarily, this distance can be 6 mm, 7 mm or 8 mm, and can be adaptively selected according to actual requirements, and no specific limitation is made here.

[0072] Preferably, as Figure 7As shown, the minimum distance between the center of the upper roll welding wheel 100 and the center of the lower roll welding wheel 200 along the length direction of the negative electrode tab 22 is greater than or equal to zero, and the maximum distance is less than the radius of the upper roll welding wheel 100 or the lower roll welding wheel 200. That is to say, during rolling, along the length direction of the negative electrode tab 22, the upper roll welding wheel 100 and the lower roll welding wheel 200 are arranged in a staggered manner, and there is a distance between their centers. However, in order to ensure the welding effect, this distance cannot be too large. The maximum distance is set as D, and the maximum distance D needs to be less than the radius of the upper roll welding wheel 100 or the lower roll welding wheel 200. Such a setting can avoid the concentration of welding points and further reduce the deformation of the negative electrode tab 22. It should be noted that the specific distance value between the center of the upper roll welding wheel 100 and the center of the lower roll welding wheel 200 along the length direction of the negative electrode tab 22 is not specifically limited in this embodiment and can be adaptively selected according to the radius of the upper roll welding wheel 100 or the lower roll welding wheel 200.

[0073] Preferably, chamfers are provided at the edges of the upper roll welding wheel 100 and the lower roll welding wheel 200 in contact with the negative electrode tab 22. By adopting such a setting, the phenomenon of cracking at the edge of the weld mark 221 of the negative electrode tab 22 due to welding can be reduced.

[0074] Furthermore, as Figure 1 shown, after the negative connection piece 3 is connected to the negative electrode tab 22, an inner protective film 4 is wrapped outside the core package 2 and the negative connection piece 3. A notch 41 is provided on one side of the inner protective film 4 for avoiding the positive electrode tab 21. The inner protective film 4 is used to insulate the negative connection piece 3 and the core package 2 from the aluminum shell 1 respectively, avoiding short circuits caused by the contact between the negative connection piece 3 and the core package 2 and the aluminum shell 1, and improving the safety of the battery cell. Exemplarily, the inner protective film 4 can adopt a relatively common PET protective film in the prior art. In other embodiments, the inner protective film 4 can also adopt other materials that can achieve insulation, which is not specifically limited in this embodiment.

[0075] Preferably, continuing to refer to Figure 1 , an insulating sheet 5 is provided outside the side of the inner protective film 4 close to the negative connection piece 3, and the insulating sheet 5 is located between the inner protective film 4 and the aluminum shell 1. That is to say, the insulating sheet 5 and the negative connection piece 3 are respectively located on both sides of the inner protective film 4. By providing the insulating sheet 5, double insulation protection can be achieved for the negative connection piece 3, the insulation effect can be further improved, and thus the safety of the battery cell can be further improved.

[0076] Furthermore, as Figure 1 and Figure 2As shown, an insulating film 6 or an insulating coating is wrapped outside the aluminum shell 1. The insulating film 6 or the insulating coating is used to insulate adjacent two battery cells, avoiding short circuit caused by contact between battery cells during grouping and improving the safety of the battery module. Exemplarily, the insulating film 6 can adopt a commonly used PET protective film in the prior art, and the insulating coating can adopt ceramic materials such as alumina and zirconia. In other embodiments, the insulating film 6 or the insulating coating can also adopt other materials or coatings capable of achieving insulation, which are not specifically limited in this embodiment.

[0077] Preferably, the difference between the length of the battery cell and the length of the core package 2 is less than 25 mm. By adopting this setting, on the premise that the core package 2 is completely accommodated in the aluminum shell 1, it is ensured that the length of the core package 2 is as long as possible, making the overall structure of the battery cell more compact and the battery cell capacity larger.

[0078] Furthermore, as Figure 8 shown, this embodiment also provides a method for manufacturing a battery cell for manufacturing the above-mentioned battery cell. The method for manufacturing the battery cell includes the following steps:

[0079] Step S1: Form the core package 2 by means of stacking or winding, and make the positive electrode tab 21 and the negative electrode tab 22 located on both sides of the core package 2 along the width direction;

[0080] Step S2: Connect the negative electrode tab 22 and the negative connection piece 3 by roll welding, and weld and connect one end of the extended negative electrode tab 22 to the negative terminal 122;

[0081] Step S3: Weld and connect the positive electrode tab 21 and the conductive component so that the positive electrode tab 21 and the positive terminal are electrically connected through the conductive component, specifically including:

[0082] Step S31: Place the core package 2 and the negative connection piece 3 into the aluminum shell 1;

[0083] Step S32: Connect the positive electrode tab 21 and one side of the aluminum shell 1 by laser welding.

[0084] Step S4: Weld the negative top cover 12 and the positive top cover 11 to both ends of the aluminum shell 1 respectively to encapsulate the aluminum shell 1.

[0085] Specifically, in step S1, the core package 2 includes multiple layers of positive electrode sheets, multiple layers of negative electrode sheets, and multiple layers of separators. The positive electrode sheets and the negative electrode sheets are alternately stacked, and the separators are disposed between adjacent positive electrode sheets and negative electrode sheets. One end of the positive electrode sheet extends by a preset width to form a positive electrode tab 21, and one end of the negative electrode sheet far from the positive electrode sheet extends by a preset width to form a negative electrode tab 22. During the production process of the battery cell, they are stacked in the order of separator, positive electrode sheet, separator, negative electrode sheet, separator in sequence, with the separator between the positive electrode sheet and the negative electrode sheet to play an isolation role, thereby obtaining the core package 2. Among them, the production processes of the positive electrode sheet and the negative electrode sheet belong to the prior art and will not be elaborated here.

[0086] In step S2, by providing a negative connection piece 3, a negative circuit is conducted between the negative electrode tab 22 and the negative terminal 122. By connecting the negative connection piece 3 and the negative electrode tab 22 through roll welding, the overcurrent capacity of the welding position between the negative electrode tab 22 and the negative connection piece 3 can be improved, and the deformation of the negative electrode tab 22 can be made smaller, with good welding flatness, which is beneficial to the assembly of the battery cell.

[0087] In step S3, the positive electrode tab 21 is directly welded to the aluminum shell 1, so that the aluminum shell 1 serves as a positive connection piece to connect with the positive electrode top cover 11 to form a conductive path, eliminating the need for a positive connection piece, simplifying the structure, reducing the cost, and improving the grouping efficiency.

[0088] It should be noted that in step S4, the positive terminal is electrically conducted with the positive electrode top cover body. After welding the positive electrode top cover 11 to the aluminum shell 1, the aluminum shell 1 is electrically conducted with the positive electrode top cover body, so that a positive conductive path is formed between the positive electrode tab 21 and the positive terminal through the aluminum shell 1.

[0089] Embodiment 2

[0090] This embodiment provides another battery cell. The structure of this battery cell is basically the same as that of the battery cell provided in Embodiment 1, and the same parts will not be elaborated here. The differences are as follows:

[0091] As Figure 9 shown, the roll welding process can also meet the design requirements of a continuous long weld mark for the whole section, that is, through roll welding, a continuously set weld mark 221 can be formed on the negative electrode tab 22, and the weld mark 221 extends along the length direction of the negative electrode tab 22 to improve the connection effect between the negative electrode tab 22 and the negative connection piece 3, thereby enhancing the overcurrent capacity of the welding position between the negative electrode tab 22 and the negative connection piece 3.

[0092] Preferably, the length of the integral weld mark 221 is greater than the circumference of the upper roll welding wheel 100 or the lower roll welding wheel 200 to ensure that the size of this section of the weld mark 221 is as large as possible, thereby further improving the current-carrying capacity of the welding position between the negative electrode tab 22 and the negative electrode connecting piece 3. It should be noted that the length of this section of the weld mark 221 can be adaptively adjusted according to the circumference of the roll welding wheel and the specific length of the negative electrode tab 22, and no specific limitation is made here.

[0093] Embodiment III

[0094] This embodiment provides another battery cell. The structure of this battery cell is basically the same as that of the battery cells provided in Embodiment I and Embodiment II, and the same parts will not be described in detail here. The differences are as follows:

[0095] The battery cell provided in this embodiment further includes a positive electrode connecting piece (not shown in the figure). The positive electrode connecting piece has the same structure as the negative electrode connecting piece 3 but different positions. The positive electrode connecting piece is located inside the aluminum shell 1 and is insulated from the aluminum shell 1. One end of the positive electrode connecting piece is connected to the positive electrode tab 21 by roll welding, and the other end is electrically connected to the positive electrode terminal. Among them, in this embodiment, the positive electrode terminal needs to be insulated from the positive electrode top cover body. One end of the negative electrode connecting piece 3 is connected to the negative electrode tab 22 by roll welding, and the other end is electrically connected to the negative electrode terminal 122, forming an overall conductive path, so that the battery cell can complete the charging and discharging functions. It should be noted that the positive electrode tab 21 and the positive electrode connecting piece are also roll welded by the roll welding device provided in Embodiment I. The form of the weld mark formed on the positive electrode tab 21 and the achieved effect are exactly the same as the structure and effect of the weld mark 221 on the negative electrode tab 22 in Embodiment I, and will not be described in detail here.

[0096] It is worth noting that the insulation between the positive electrode connecting piece and the aluminum shell 1 can be achieved by the inner protective film 4 in Embodiment I. At this time, the setting of the notch 41 needs to be cancelled, and the inner protective film 4 is also wrapped outside the positive electrode connecting piece to insulate the positive electrode connecting piece and the core package 2 from the aluminum shell 1, avoiding short circuits caused by the contact between the positive electrode connecting piece and the core package 2 and the aluminum shell 1, thereby improving the safety of the battery cell.

[0097] As Figure 10 shown, this embodiment also provides another method for manufacturing a battery cell, which is used to manufacture the battery cell provided in this embodiment. The manufacturing method of this battery cell includes the following steps:

[0098] Step S1: Form the core package 2 by means of stacking or winding, and make the positive electrode tab 21 and the negative electrode tab 22 located on both sides of the core package 2 in the width direction;

[0099] Step S2: Connect the negative electrode tab 22 and the negative electrode connecting piece 3 by roll welding, and weld the extended end of the negative electrode tab 22 to the negative electrode terminal 122;

[0100] Step S3: Weld and connect the positive electrode tab 21 with the conductive component so that the positive electrode tab 21 and the positive terminal are electrically connected through the conductive component. Specifically, it includes:

[0101] Step S31: Connect the positive electrode tab 21 and the positive electrode connecting piece by roll welding;

[0102] Step S32: Place the core package 2, the negative electrode connecting piece 3 and the positive electrode connecting piece into the aluminum shell 1, and weld and connect the positive electrode connecting piece with the positive terminal.

[0103] Step S4: Weld the negative electrode top cover 12 and the positive electrode top cover 11 to both ends of the aluminum shell 1 respectively to encapsulate the aluminum shell 1.

[0104] It should be noted that the manufacturing method of the battery cell provided in this embodiment is the same as steps S1, S2 and S4 of the manufacturing method of the battery cell in Embodiment 1, which will not be elaborated here. The difference lies in the specific operation of step S3. In step S3, by setting the positive electrode connecting piece, a positive electrode conductive path can be formed between the positive electrode tab 21 and the positive terminal. Connecting the positive electrode connecting piece and the positive electrode tab 21 by roll welding can improve the current-carrying capacity of the welding position between the positive electrode tab 21 and the positive electrode connecting piece, thereby improving the overall performance of the battery cell. It can also make the deformation of the positive electrode tab 21 smaller and the welding flatness better, which is beneficial to the assembly of the battery cell.

[0105] Obviously, the above embodiments of the present invention are only examples for clearly explaining the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. The battery cell, characterized in that, comprises: an aluminum shell (1), with a negative electrode top cover (12) and a positive electrode top cover (11) respectively connected to its opposite ends. The negative electrode top cover (12) includes a negative electrode top cover body (121) and a negative terminal (122) insulatedly arranged on the negative electrode top cover body (121). The positive electrode top cover (11) includes a positive electrode top cover body and a positive terminal arranged on the positive electrode top cover body; a core package (2), accommodated in the aluminum shell (1). The length of the core package (2) is greater than its width. Positive electrode tabs (21) and negative electrode tabs (22) respectively extend from opposite sides of the core package (2) along the width direction, so as to shorten the conduction path. The positive electrode tab (21) is electrically connected to the positive terminal; a negative connection piece (3), located in the aluminum shell (1) and insulatedly arranged from the aluminum shell (1). The negative connection piece (3) is bent, with one end connected to the negative electrode tab (22) by roll welding and the other end electrically connected to the negative terminal (122). After the negative electrode tab (22) and the negative connection piece (3) are stacked, they are placed between an upper roll welding roller (100) and a lower roll welding roller (200). Chamfers are provided at the edges of the upper roll welding roller (100) and the lower roll welding roller (200) that contact the negative electrode tab (22); the positive electrode tab (21) is connected to one side of the aluminum shell (1) by laser welding, and the aluminum shell (1) is electrically conducted with the positive terminal; an inner protective film (4) is wrapped outside the core package (2) and the negative connection piece (3). A notch (41) is provided on one side of the inner protective film (4), and the notch (41) is used to avoid the positive electrode tab (21).

2. The battery cell according to claim 1, characterized in that, multiple welding imprints (221) are formed on the negative electrode tab (22) at intervals along the length direction of the negative electrode tab (22).

3. The battery cell according to claim 2, characterized in that, the distance between two adjacent welding imprints (221) is greater than 5 mm.

4. The battery cell according to claim 1, characterized in that, a continuous whole-section welding imprint (221) is formed on the negative electrode tab (22).

5. The battery cell according to claim 4, characterized in that, the upper roll welding roller (100) and the lower roll welding roller (200) have the same diameter, and the length of the welding imprint (221) is greater than the circumference of the upper roll welding roller (100) or the lower roll welding roller (200).

6. The battery cell according to claim 5, characterized in that, the minimum distance along the length direction of the negative electrode tab (22) between the centers of the upper roll welding roller (100) and the lower roll welding roller (200) is greater than or equal to zero, and the maximum distance is less than the radius of the upper roll welding roller (100) or the lower roll welding roller (200).

7. The battery module, including a battery box, characterized in that, it further includes the battery cell according to any one of claims 1-6, and the battery cell is accommodated in the battery box.

8. Method for manufacturing an electrode assembly, characterized in that, it is used to manufacture the electrode assembly according to any one of claims 1-6, and the method for manufacturing the electrode assembly includes: Step S1: Form the core package (2) by stacking or winding, and make the positive electrode tab (21) and the negative electrode tab (22) located on both sides of the core package (2) along the width direction; Step S2: Connect the negative electrode tab (22) and the negative connection piece (3) by roll welding, and weld one end of the extended negative connection piece (3) to the negative terminal (122); Step S3: Weld the positive electrode tab (21) to the conductive component, so that the positive electrode tab (21) and the positive terminal are electrically connected through the conductive component.

9. The method for manufacturing an electrode assembly according to claim 8, characterized in that, the specific steps of Step S3 include: Step S31: Place the core package (2) and the negative connection piece (3) into the aluminum shell (1); Step S32: Weld the positive electrode tab (21) to one side of the aluminum shell (1) by laser welding.

10. The method for manufacturing an electrode assembly according to any one of claims 8-9, characterized in that, the method for manufacturing the electrode assembly further includes: Step S4: Weld the negative top cover (12) and the positive top cover (11) to both ends of the aluminum shell (1) respectively to encapsulate the aluminum shell (1).

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