Battery cell and battery pack

Abstract

The invention relates to the technical field of batteries, and discloses a battery cell and a battery pack, the battery cell comprises a pole group, the pole group comprises a pole group body and a pole lug, the pole lug is connected to the side edge of the pole group body, a pre-welding print is formed on the pole lug, the size of the pre-welding print along the length direction of the pole lug is L1, and L1 is greater than or equal to 20mm and less than or equal to 50mm; the tab is suitable for being cut along a cutting line, and the cutting line extends in the length direction of the tab and penetrates through the pre-welding print; the size of the pre-welding print before cutting along the width direction of the tab is W1, the size of the pre-welding print after cutting along the width direction of the tab is W2, and W1-W2 is more than or equal to 0.5 mm and less than or equal to 2.5 mm. According to the technical scheme, tab cutting process parameters are reasonably optimized and defined, and a reasonable cut width of a pre-welding weld mark is ensured, so that the tab is not cracked after being cut while the alignment degree of the end part, far away from the pole group body, of the tab is ensured, short circuit of a battery cell caused by improper tab cutting is avoided, and the overcurrent requirement is met.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to battery cells and battery packs. Background Art

[0002] The battery cell has the advantages of small size, light weight, high specific energy, etc., and has a large application market. The battery cell is mainly composed of a pole group, a transfer sheet, and a packaging film. The transfer sheet is welded to the pole ear of the pole group. The packaging film encapsulates the pole group and part of the transfer sheet, and seals it by hot pressing. Among them, the pole group is composed of several layers of pole pieces and diaphragms stacked together. Several pole ears need to be pre-welded into one and cut before being welded to the transfer sheet. However, in the actual production process, the range of process parameters for pole ear pre-welding and pole ear cutting is relatively wide, and there are often improper cutting phenomena such as misalignment of the pole ear ends after cutting, which leads to the pole ear contacting with the pole piece inside the battery cell or the pole ear entering the sealing area of ​​the packaging film, causing problems such as short circuit of the battery cell, which is very dangerous. Summary of the invention

[0003] In view of this, the present invention provides a battery cell and a battery pack to solve the problem of battery cell short circuit caused by improper cutting after pre-welding of the tabs.

[0004] In the first aspect, the present invention provides a battery cell, comprising: a pole group, comprising a pole group body and a pole ear, the pole ear being connected to the side of the pole group body, a pre-weld mark being formed on the pole ear, the dimension of the pre-weld mark along the length direction of the pole ear being L1, wherein 20mm≤L1≤50mm; the pole ear being suitable for cutting along a cutting line, the cutting line extending along the length direction of the pole ear and passing through the pre-weld mark; the dimension of the pre-weld mark along the width direction of the pole ear before cutting is W1, and the dimension of the pre-weld mark along the width direction of the pole ear after cutting is W2, wherein 0.5mm≤W1-W2≤2.5mm.

[0005] Beneficial effect: By pre-welding the pole ear of the pole group, the pole ears of the multi-layer pole piece are connected as one, and by limiting the dimension L1 of the pre-welding mark along the length direction of the pole ear to be within the range of 20mm to 50mm, the stability of the pole ear connection after pre-welding can be ensured and the overcurrent requirement can be met, which is convenient for the subsequent battery cell assembly process. By cutting the pole ear along the cutting line parallel to the length direction of the pole ear and passing through the pre-welding mark, the partial area of ​​the pole ear away from the pole group body and the partial area of ​​the pre-welding mark away from the pole group body are cut. Cut off, and at the same time limit the width difference of the pre-weld weld mark before and after cutting to be in the range of 0.5mm to 2.5mm, reasonably optimize and define the tab cutting process parameters, ensure that the pre-weld weld mark is cut off to a reasonable width, so as to ensure the end alignment of the tab away from the pole group body while ensuring that the tab does not crack after cutting, thereby avoiding short circuit of the battery cell due to improper tab cutting, ensuring the safety of the battery cell, and at the same time ensuring that the pre-weld weld mark after cutting still has sufficient size to meet the overcurrent requirement, thereby ensuring the performance of the battery cell.

[0006] In an optional embodiment, the dimension W2 of the pre-weld mark after cutting along the width direction of the tab is in the range of 2.5 mm ≤ W2 ≤ 4.5 mm.

[0007] Beneficial effect: By setting the width of the pre-weld mark after cutting to a value within the range of 2.5 mm to 4.5 mm, both the overcurrent requirement can be met and the production cost can be controlled.

[0008] In an optional embodiment, the dimension W1 of the pre-weld mark before cutting along the width direction of the tab is in the range of 3 mm ≤ W1 ≤ 5 mm.

[0009] Beneficial effect: By setting the dimension W1 of the pre-weld weld mark before cutting along the width direction of the pole ear to be in the range of 3mm to 5mm, it can not only meet the overcurrent requirements, but also control the production cost, ensure the welding quality, avoid the influence of welding on the pole group body, and thus ensure the performance of the battery cell.

[0010] In an optional implementation, the area of ​​the pre-weld mark after cutting is S1, and the area of ​​the tab after cutting is S0, wherein 0.1≤S1 / S0≤0.3.

[0011] Beneficial effect: By setting the ratio S1 / S0 between the area S1 of the pre-weld mark after cutting and the area S0 of the tab after cutting to be in the range of 0.1 to 0.3, it can not only ensure that the tab has sufficient current capacity, but also reduce costs and ensure welding quality, thereby improving battery performance.

[0012] In an optional embodiment, the width of the electrode tab after cutting is A2, wherein 5mm≤A2≤10mm.

[0013] Beneficial effect: By setting the width A2 of the cut tab within the range of 5mm to 10mm, it can not only ensure the convenience of subsequent welding between the tab and the adapter and improve the welding quality, but also avoid waste of materials, reduce production costs, facilitate packaging, improve tab stability, and avoid tab tearing.

[0014] In an optional implementation, the width of the tab before cutting is A1, wherein 8 mm ≤ A1 ≤ 15 mm.

[0015] Beneficial effect: By setting the width A1 of the tab before cutting to a value within the range of 8 mm to 15 mm, both the overcurrent requirement can be met and the production cost can be controlled.

[0016] In an optional embodiment, the length of the pole ear is L0, wherein 30 mm ≤ L0 ≤ 70 mm.

[0017] Beneficial effect: By setting the length L0 of the pole ear to a value between 30 mm and 70 mm, it can be ensured that the pole ear provides a sufficient design area for the pre-welding weld mark and the current capacity is guaranteed, and it can also avoid wasting materials and reduce production costs.

[0018] In an optional embodiment, the battery cell further includes: a transfer plate welded on the pole ear; and a packaging film wrapped around the outer side of the pole group, the packaging film extending out from a side of the transfer plate away from the pole ear.

[0019] Beneficial effects: By arranging the adapter to be welded with the pole ear and extending out of the packaging film, the packaging film forms a closed space for protecting the pole group, and the adapter is used to connect with external equipment or other batteries, with a simple structure and high reliability.

[0020] In an optional embodiment, the electrode tabs include a positive electrode tab and a negative electrode tab; the pre-welding pressure for forming the pre-welding mark on the positive electrode tab is 1±0.5Bar, the pre-welding amplitude is 45%±10%, and the pre-welding energy is 30±20Ws; the pre-welding pressure for forming the pre-welding mark on the negative electrode tab is 1.5±0.5Bar, the pre-welding amplitude is 65%±10%, and the pre-welding energy is 150±100Ws.

[0021] Beneficial effect: For different materials, using different welding parameters in the pre-welding process can effectively improve the pre-welding yield, thereby improving the qualified rate of battery cells.

[0022] In a second aspect, the present invention further provides a battery pack, comprising: the above-mentioned battery cell. Since the battery pack comprises the battery cell and has the same effect as the battery cell, it will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 This is a schematic structural diagram of a battery cell according to an embodiment of the present invention;

[0025] Figure 2 is a schematic structural diagram of a pole group before cutting according to an embodiment of the present invention;

[0026] Figure 3 It is a schematic structural diagram of the electrode group after cutting according to an embodiment of the present invention.

[0027] Description of reference numerals:

[0028] 1. Pole group body; 101. Positive electrode sheet; 102. Negative electrode sheet; 103. Diaphragm; 201. Positive electrode ear; 202. Negative electrode ear; 3. Pre-welding mark; 401. Positive electrode adapter; 402. Negative electrode adapter; 5. Packaging film; 501. Seal; 6. Sealant. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0030] Combine the following Figures 1 to 3 , describing an embodiment of the present invention.

[0031] According to an embodiment of the present invention, on the one hand, a battery cell is provided, including a pole group, the pole group including a pole group body 1 and a pole ear, the pole ear is connected to the side of the pole group body 1, a pre-weld mark 3 is formed on the pole ear, and the dimension of the pre-weld mark 3 along the length direction of the pole ear is L1, wherein 20mm≤L1≤50mm; the pole ear is suitable for cutting along a cutting line, the cutting line extends along the length direction of the pole ear and passes through the pre-weld mark 3; the dimension of the pre-weld mark 3 along the width direction of the pole ear before cutting is W1, and the dimension of the pre-weld mark 3 along the width direction of the pole ear after cutting is W2, wherein 0.5mm≤W1-W2≤2.5mm. Wherein, the length direction refers to Figures 2 to 3 The arrow in the middle refers to the "length direction", and the width direction refers to Figures 2 to 3The “width direction” indicated by the middle arrow is the same direction as the length direction of the pole ear and the extension direction of the side of the pole group body connected to the pole ear, and the width direction is perpendicular to the length direction.

[0032] In the battery cell of the present embodiment, the pole ears of the electrode group are pre-welded so that the pole ears of the multi-layer electrode sheets are connected as one, and the dimension L1 of the pre-welding mark 3 along the length direction of the pole ear is limited to a value within the range of 20 mm to 50 mm, so that the stability of the pole ear connection after pre-welding and the satisfaction of the overcurrent requirement can be ensured, and the subsequent battery cell assembly process is facilitated. The pole ear is cut along a cutting line parallel to the length direction of the pole ear and passing through the pre-welding mark 3, and a partial area of ​​the pole ear away from the pole group body 1 and a portion of the pre-welding mark 3 away from the pole group body 1 are cut. Cut off in different areas, and limit the width difference of the pre-weld mark 3 before and after cutting to be within the range of 0.5mm to 2.5mm. Reasonably optimize and define the tab cutting process parameters to ensure that the pre-weld mark 3 is cut off to a reasonable width, thereby ensuring the alignment of the end of the tab away from the pole group body 1 and ensuring that the tab does not crack after cutting, thereby avoiding short circuit of the battery cell due to improper tab cutting and ensuring the safety of the battery cell. At the same time, it can also ensure that the pre-weld mark 3 after cutting still has sufficient size to meet the overcurrent requirement, thereby ensuring the performance of the battery cell.

[0033] It should be noted that the electrode group of the battery cell is stacked in the order of negative electrode sheet 102, separator 103, positive electrode sheet 101, negative electrode sheet 102, ..., a negative current collector extends from the negative electrode sheet 102, and a positive current collector extends from the positive electrode sheet 101. Several positive current collectors are connected into an integrated positive electrode ear 201 after pre-welding, and several negative current collectors are connected into an integrated negative electrode ear 202 after pre-welding, so that a pre-welding mark 3 is formed on the positive electrode ear 201 and the negative electrode ear 202 respectively, and the electrode sheets of the same polarity are electrically connected through the pre-welding mark, and the current flows through the pre-welding mark 3. The size of the pre-welding mark 3 directly affects the current carrying capacity of the electrode ear; the electrode ear after pre-welding needs to be cut to cut off a part of the electrode ear away from the electrode group body 1 and a part of the pre-welding mark 3 away from the electrode group body 1, so that the end of the electrode ear away from the electrode group body 1 is aligned. To avoid direct contact between the surfaces of the positive electrode sheet 101 and the negative electrode sheet 102 , the length and width of the diaphragm 103 are larger than the corresponding dimensions of the electrode sheet. The electrode assembly body 1 includes the area with active material on the electrode sheet and the diaphragm 103 .

[0034] If the difference between the dimension W2 of the pre-weld mark 3 along the width direction of the pole ear after cutting and the dimension W1 of the pre-weld mark 3 along the width direction of the pole ear before cutting is less than 0.5mm, the part of the pre-weld mark 3 that is cut off is too small, and there may be a situation where the collector of one or more layers of the pole sheet is not cut, and the end of the pole ear away from the pole group body 1 is uneven, so there is a risk of the pole ear contacting the pole group body 1 and causing a short circuit in the battery cell, or there is a risk of cracking on the side of the pole ear away from the pole group body 1 after cutting; if the difference between W2 and W1 is greater than 2.5mm, the part of the pre-weld mark 3 that is cut off is too large, the size of the remaining pre-weld mark after cutting is insufficient, the flow area is too small, and it is difficult to meet the flow requirement.

[0035] In one embodiment, the dimension W1 of the pre-weld weld mark 3 along the width direction of the pole ear before cutting is in the range of 3mm≤W1≤5mm. It should be noted that the dimension W1 of the pre-weld weld mark 3 along the width direction of the pole ear before cutting is the width of the pre-weld weld mark 3. If W1 is less than 3mm, the width of the pre-weld weld mark 3 before cutting is too small, and the flow area between the pole pieces of the same polarity in each layer electrically connected by the pre-weld weld mark 3 is too small. After a part of the pre-weld weld mark 3 is cut, the flow area is even smaller, and it is difficult to meet the flow requirements. If W1 is greater than 5mm, the width of the pre-weld weld mark 3 is too large, which wastes welding energy and increases costs. It will also increase the difficulty of welding due to the excessively large welding width, resulting in a decrease in welding quality and even affecting the pole group body 1. Therefore, by setting the dimension W1 of the pre-weld weld mark 3 before cutting along the width direction of the pole ear to be in the range of 3mm to 5mm, it is possible to meet the overcurrent requirements, control the production cost, ensure the welding quality, avoid the impact of welding on the pole group body 1, and thus ensure the performance of the battery cell.

[0036] In one embodiment, the dimension W2 of the pre-weld weld mark 3 after cutting along the width direction of the pole ear has a value range of: 2.5mm≤W2≤4.5mm. The area of ​​the pre-weld weld mark 3 after cutting is the actual flow area of ​​the pole ear of the battery cell. If the width W2 of the pre-weld weld mark 3 after cutting is less than 2.5mm, the width of the pre-weld weld mark 3 after cutting is too small, and the actual flow area of ​​the pole ear is too small to meet the flow requirements. If W2 is greater than 4.5mm, the width of the pre-weld weld mark 3 after cutting is too large. Correspondingly, the width of the pre-weld weld mark 3 before cutting is too large, which wastes welding energy and increases costs. Therefore, by setting the width of the pre-weld weld mark 3 after cutting to a value within the range of 2.5mm to 4.5mm, both the flow requirements can be met and the production costs can be controlled.

[0037] In one embodiment, the area of ​​the pre-weld mark 3 after cutting is S1, and the area of ​​the tab after cutting is S0, wherein 0.1≤S1 / S0≤0.3. It should be noted that S1 / S0 represents the area ratio of the pre-weld mark 3 after cutting on the tab after cutting, and the units of S1 and S0 are both mm. 2 If S1 / S0 is less than 0.1, the area of ​​the pre-weld weld mark 3 after cutting on the cut pole ear accounts for too small a proportion, and the flow area provided by the pre-weld weld mark 3 is insufficient, which affects the flow capacity of the pole ear and thus affects the performance of the battery cell; if S1 / S0 is greater than 0.3, the area of ​​the pre-weld weld mark 3 after cutting on the cut pole ear accounts for too large a proportion, which not only wastes welding energy and increases costs, but also increases welding difficulty and affects welding quality. Therefore, by setting the ratio S1 / S0 between the area S1 of the pre-weld weld mark 3 after cutting and the area S0 of the cut pole ear within the range of 0.1 to 0.3, it can not only ensure that the pole ear has sufficient flow capacity, but also reduce costs, ensure welding quality, and thus improve battery cell performance.

[0038] In one embodiment, the width of the cut pole ear is A2, wherein 5mm≤A2≤10mm. It should be noted that one of the longer sides of the pole ear is connected to the pole piece in the pole group body 1, and the distance from the other longer side opposite to the side to the pole group body 1 is the width of the pole ear. Specifically, the width of the pole ear refers to the distance from the side of the pole ear away from the pole group body 1 to the diaphragm 103. If the width A2 of the cut pole ear is less than 5mm, the width of the cut pole ear is too small, which is not conducive to the subsequent welding of the pole ear and the adapter, and increases the difficulty of the welding operation. If A2 is greater than 10mm, the width of the cut pole ear is too large, which wastes materials and affects the packaging of the battery cell. In addition, the stability of the pole ear along the width direction is poor, and the pole ear is prone to tearing. Therefore, by setting the width A2 of the cut tab within the range of 5 mm to 10 mm, it can not only ensure the convenience of subsequent welding between the tab and the adapter and improve the welding quality, but also avoid waste of materials, reduce production costs, facilitate packaging, improve tab stability, and avoid tab tearing.

[0039] In one embodiment, the width of the pole ear before cutting is A1, wherein 8mm≤A1≤15mm. If the width A1 of the pole ear before cutting is less than 8mm, the width of the pole ear before cutting is too small, and it is difficult to provide sufficient setting space for the pre-welding weld mark 3, and it is difficult to meet the overcurrent requirements. It will also cause the pre-welding weld mark 3 to be too close to the edge of the pole ear, resulting in poor welding such as cold welding, or affecting the pole group body 1, thereby reducing the performance of the battery cell; if A1 is greater than 15mm, the width of the pole ear before cutting is too large, too much material is used, and the production cost is high. Therefore, by setting the width A1 of the pole ear before cutting to a value within the range of 8mm to 15mm, both the overcurrent requirements can be met and the production costs can be controlled.

[0040] In one embodiment, the length of the tab is L0, where 30 mm ≤ L0 ≤ 70 mm. Figures 2 to 3 The dimension of the "length direction" indicated by the middle arrow, if the length L0 of the pole ear is less than 30mm, the length of the pole ear is too short, and the pole ear cannot reserve enough space for the pre-weld weld mark 3 in the length direction, resulting in the pre-weld weld mark 3 being too close to the edge of the pole ear along the length direction, which is prone to poor welding such as cold welding and welding slag, thereby affecting the current carrying capacity of the pole ear; if L0 is greater than 70mm, the length of the pole ear is too long, too much material is used, the production cost is high, and the processing is inconvenient. Therefore, by setting the length L0 of the pole ear to a value between 30mm and 70mm, it can be ensured that the pole ear provides sufficient design area for the pre-weld weld mark 3 to ensure the current carrying capacity, and it can also avoid wasting materials and reduce production costs.

[0041] In one embodiment, the battery cell further includes: a transfer plate and a packaging film 5. The transfer plate is welded on the pole ear; the packaging film 5 is wrapped around the outside of the pole group, and the side of the transfer plate away from the pole ear extends out of the packaging film 5. By arranging the transfer plate to be welded to the pole ear and extending out of the packaging film 5, the packaging film 5 forms a closed space for protecting the pole group, and the transfer plate is used to connect with an external device or other battery cells, with a simple structure and high reliability. Among them, after the insulating film is wrapped around the outside of the pole group, it is packaged with the packaging film 5 to further protect the pole group.

[0042] Specifically, the packaging film 5 includes an upper packaging film and a lower packaging film. The upper packaging film is formed with a pit corresponding to the electrode group. During the assembly of the battery cell, the electrode group is first placed in the pit on the upper packaging film, and then covered with the lower packaging film. The four sides of the upper packaging film and the lower packaging film are hot-melt sealed to form a seal 501 to form an enclosed space that wraps the electrode group.

[0043] Preferably, the packaging film 5 is an aluminum-plastic film, which has the advantages of good protection performance, high safety performance, high energy density, good stability and the like.

[0044] In one embodiment, a sealant 6 is provided between the adapter and the packaging film 5 , and the seal 501 is pressed on the sealant 6 to improve the sealing between the packaging film 5 and the adapter and ensure the safety of the battery cell.

[0045] In one embodiment, the tabs include a positive tab 201 and a negative tab 202, the adapter includes a positive adapter 401 and a negative adapter 402, the positive adapter 401 is welded to the positive tab 201, and the negative adapter 402 is welded to the negative tab 202, thereby achieving separate lead-out of the positive and negative electrodes of the battery cell.

[0046] In one embodiment, the pre-welding pressure for forming the pre-welding mark 3 on the positive electrode ear 201 is 1±0.5Bar, the pre-welding amplitude is 45%±10%, and the pre-welding energy is 30±20Ws; the pre-welding pressure for forming the pre-welding mark 3 on the negative electrode ear 202 is 1.5±0.5Bar, the pre-welding amplitude is 65%±10%, and the pre-welding energy is 150±100Ws. It should be noted that the positive electrode ear 201 and the negative electrode ear 202 are made of different materials, the positive electrode ear 201 is aluminum, and the negative electrode ear 202 is copper. For different materials, different welding parameters are used in the pre-welding process, which can effectively improve the pre-welding yield, thereby improving the qualified rate of the battery cell.

[0047] The battery cell of this embodiment reasonably optimizes and defines the tab cutting process parameters, which can effectively ensure the alignment of the tab ends, avoid short circuits caused by misaligned tab ends, and avoid improper tab cutting that causes the tabs to enter the area where the packaging film 5 and the seal 501 are located, thereby avoiding the risk of causing micro short circuits.

[0048] The following describes the experimental results of testing cells with different parameter values ​​to experimentally verify the parameter values ​​of the cell.

[0049] Table 1 Cell verification results for different values ​​of W1-W2 and S1 / S0

[0050]

[0051] It can be seen from Table 1 that for the battery cells of Implementation Examples 1 to Implementation Examples 6, the difference W1-W2 between the dimension W1 of the pre-weld weld mark 3 along the width direction of the pole ear before cutting and the dimension W2 of the pre-weld weld mark 3 along the width direction of the pole ear after cutting is within the range of 0.5 mm to 2.5 mm specified in the present application, and the ratio S1 / S0 between the area S1 of the pre-weld weld mark 3 after cutting and the area S0 of the pole ear after cutting is within the range of 0.1 to 0.3 specified in the present application. The experimental results show that Implementation Examples 1 to Implementation Examples 6 The battery cells of Comparative Case 1 can meet the overcurrent requirements; while for the battery cell of Comparative Case 1, the value of W1-W2 is 0.4mm, which is less than 0.5mm, and the value of S1 / S0 is 0.4, which is greater than 0.3, and is not within the scope defined in the present application. Although the overcurrent requirements can be met, the side of the cut ear away from the electrode group body is cracked; for the battery cells of Comparative Case 2 and Comparative Case 3, the values ​​of W1-W2 are both greater than 2.5mm, and S1 / S0 are both less than 0.1, which are not within the scope defined in the present application, the overcurrent requirements cannot be met, and the cost is relatively high.

[0052] In summary, when the width difference before and after the pre-weld weld mark 3 is within the range of 0.5mm to 2.5mm, it can ensure the alignment of the end of the pole ear away from the pole group body 1, while ensuring that the pole ear does not crack after cutting, thereby avoiding short circuit of the battery cell due to improper cutting of the pole ear, ensuring the safety of the battery cell, and at the same time ensuring that the pre-weld weld mark 3 after cutting still has sufficient size to meet the overcurrent requirements and ensure the performance of the battery cell; when the ratio S1 / S0 between the area S1 of the pre-weld weld mark 3 after cutting and the area S0 of the pole ear after cutting is within the range of 0.1 to 0.3, it can not only ensure that the pole ear has sufficient overcurrent capacity, but also reduce costs, ensure welding quality, and thus improve battery cell performance.

[0053] According to an embodiment of the present invention, in another aspect, a battery pack is provided, comprising: the above-mentioned battery cell. Preferably, the battery pack comprises a plurality of battery cells, and the plurality of battery cells are electrically connected to each other.

[0054] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that: include: A pole group, comprising a pole group body and a pole ear, wherein the pole ear is connected to a side of the pole group body, a pre-welding mark is formed on the pole ear, and a dimension of the pre-welding mark along the length direction of the pole ear is L1, wherein 20 mm ≤ L1 ≤ 50 mm; The pole lug is suitable for cutting along a cutting line, which extends along the length direction of the pole lug and passes through the pre-weld weld mark; the size of the pre-weld weld mark along the width direction of the pole lug before cutting is W1, and the size of the pre-weld weld mark along the width direction of the pole lug after cutting is W2, wherein 0.5mm≤W1-W2≤2.5mm.

2. The battery cell according to claim 1, characterized in that: The dimension W2 of the pre-weld mark after cutting along the width direction of the tab is in the range of 2.5 mm ≤ W2 ≤ 4.5 mm.

3. The battery cell according to claim 1, characterized in that: The dimension W1 of the pre-weld mark before cutting along the width direction of the tab is in the range of 3 mm ≤ W1 ≤ 5 mm.

4. The battery cell according to claim 1, characterized in that: The area of ​​the pre-weld mark after cutting is S1, and the area of ​​the tab after cutting is S0, wherein 0.1≤S1 / S0≤0.

3.

5. The battery cell according to claim 4, characterized in that: The width of the electrode tab after cutting is A2, wherein 5mm≤A2≤10mm.

6. The battery cell according to claim 1, characterized in that: The width of the tab before cutting is A1, wherein 8mm≤A1≤15mm.

7. The battery cell according to claim 1, characterized in that: The length of the pole ear is L0, wherein 30mm≤L0≤70mm.

8. The battery cell according to any one of claims 1 to 7, characterized in that: The battery cell also includes: A transfer plate, welded on the pole lug; A packaging film is wrapped around the outer side of the electrode group, and the packaging film extends out from a side of the adapter sheet away from the electrode ear.

9. The battery cell according to claim 8, characterized in that: The tabs include a positive tab and a negative tab; The pre-welding pressure for forming the pre-welding weld mark on the positive electrode ear is 1±0.5 Bar, the pre-welding amplitude is 45%±10%, and the pre-welding energy is 30±20 Ws; The pre-welding pressure for forming the pre-welding weld mark on the negative electrode ear is 1.5±0.5 Bar, the pre-welding amplitude is 65%±10%, and the pre-welding energy is 150±100 Ws.

10. A battery pack, characterized in that: include: The battery cell according to any one of claims 1 to 9.

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