Battery and battery pack

Abstract

The invention relates to the technical field of batteries, and discloses a battery and a battery pack. The battery comprises a pole group, the pole group comprises a pole group body and a pole lug, the pole lug extends out of a partial region at the side edge of the pole group body along a first direction, a welding mark is suitable for being formed on the pole lug after the pole lug is pre-welded, the orthographic projection area of the welding mark on the surface of the pole lug is S1, the surface area of the pole lug is S2, and S1 and S2 meet the relational expression that S1 / S2 is larger than or equal to 0.18 and smaller than or equal to 0.35; the packaging film coats the outer side of the pole group so as to seal and package the pole group; and one end of the switching piece is welded on the tab, and the other end of the switching piece extends out of the packaging film. According to the tab pre-welding method, poor welding such as insufficient welding, hole explosion and too small welding drawing force of a welding mark on the tab in the tab pre-welding process can be avoided, it is guaranteed that the welding mark can meet the over-current requirement of a battery, abnormal conditions such as welding deviation, too large drawing force of the welding mark on the tab and tab tearing can be avoided, and therefore the welding yield is increased.

Description

Technical Field

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

[0002] The battery is mainly composed of an electrode group and a packaging film. The packaging film covers the outside of the electrode group to seal the electrode group. The pole ear on the electrode group is led out of the packaging film by the adapter to realize the connection between the electrode group and other batteries or external circuits. Among them, the electrode group is composed of several layers of positive electrode sheets, diaphragms and negative electrode sheets. The positive current collectors of several layers of positive electrode sheets form positive pole ears, and the negative current collectors of several layers of negative electrode sheets form negative pole ears. The positive and negative pole ears are welded with a adapter respectively. Before the positive / negative pole ears are welded with the adapter, the pole ears need to be pre-welded to gather the scattered pole ears to realize the electrical connection between the pole sheets of the same polarity, and to facilitate the subsequent welding with the adapter. However, there are not many restrictions on the process steps of pole ear pre-welding in the prior art. During the pole ear pre-welding process, the pre-welding result is greatly affected by human factors such as the work experience of the operator, the consistency is poor, and it is easy to have poor welding such as cold welding and damage to the pole ears, resulting in a low welding yield, which is not conducive to saving production costs. Summary of the invention

[0003] In view of this, the present invention provides a battery and a battery pack to solve the problem of low welding yield during the tab pre-welding process.

[0004] In a first aspect, the present invention provides a battery, comprising: a pole group, comprising a pole group body and a pole ear, the pole ear extending from a partial area at the side of the pole group body along a first direction, the pole ear being suitable for forming a weld mark after the pole ear is pre-welded, the orthographic projection area of ​​the weld mark on the surface of the pole ear is S1, and the surface area of ​​the pole ear is S2, wherein S1 and S2 satisfy the relationship: 0.18≤S1 / S2≤0.35; a packaging film, coated on the outside of the pole group to seal and package the pole group; a transfer plate, one end of the transfer plate is welded to the pole ear and the other end extends out of the packaging film.

[0005] Beneficial effect: By pre-welding the pole lugs, the pole lugs on the pole pieces of the same polarity in the pole group are gathered together to achieve electrical connection between the pole pieces of the same polarity, and the integrity is good, which is convenient for the subsequent welding operation between the pole lug and the adapter. At the same time, by setting the area ratio S1 / S2 of the weld mark formed by pre-welding on the pole lug surface to a value between 0.18 and 0.35, it is possible to avoid poor welding such as cold welding, blown holes, and too small welding pull-out force of the weld mark on the pole lug during the pre-welding process of the pole lug, and ensure that the weld mark can meet the overcurrent requirements of the battery, and avoid abnormal conditions such as welding deviation, excessive pull-out force of the weld mark on the pole lug, and pole lug tearing, thereby improving the welding quality and the production line yield.

[0006] In an optional embodiment, the pole lug is rectangular, the rectangle of the pole lug is a first rectangle, the orthographic projection of the weld mark on the surface of the pole lug is a rectangle, the orthographic projection of the weld mark on the surface of the pole lug is a second rectangle, the short side of the first rectangle and the short side of the second rectangle are both parallel to the first direction, the long side of the first rectangle and the long side of the second rectangle are both parallel to the second direction, wherein the second direction is perpendicular to the first direction.

[0007] Beneficial effect: By setting the tabs and the positive projections printed on the tabs to be rectangular, the rectangular structure is easy to process and shape, and it is also easy to control the size, which is conducive to achieving standardization in the battery production process, improving processing accuracy and ensuring production quality.

[0008] In an optional embodiment, the size of the weld mark along the first direction is A; in the first direction, the vertical distance between the side of the pole ear away from the pole group body and the pole group body is C; wherein 0.3≤A / C≤1 / 2.

[0009] Beneficial effects: It is convenient for the pre-welding process of the tabs, avoids the edge of the tabs from warping or the tabs from tearing, and avoids damage to the diaphragm during welding, thereby ensuring welding quality and improving welding yield.

[0010] In an optional implementation, a value range of a dimension A of the weld mark along the first direction is: 3mm≤A≤5mm.

[0011] Beneficial effects: It is easy to process, meets the overcurrent requirements, avoids damage to the diaphragm during welding, reduces welding difficulty, ensures welding quality, and improves welding yield.

[0012] In an optional embodiment, in the first direction, a vertical distance C between a side of the pole lug away from the pole group body and the pole group body is in the range of 8 mm ≤ C ≤ 15 mm.

[0013] Beneficial effects: It can not only ensure that the tabs meet the overcurrent requirements and reduce the processing difficulty, but also avoid the tabs from tearing, improve the battery qualification rate, and at the same time save materials and control costs.

[0014] In an optional embodiment, a dimension of the weld mark along the second direction is B, and a dimension of the tab along the second direction is D, wherein 0.5≤B / D≤0.8.

[0015] Beneficial effects: It can not only prevent the edge of the pole ear from warping and affecting the subsequent assembly process, but also reduce the difficulty of welding, avoid welding deviation, and improve the welding yield.

[0016] In an optional implementation, a dimension B of the weld mark along the second direction has a value range of 20 mm ≤ B ≤ 50 mm.

[0017] Beneficial effects: It can ensure that the tabs meet the overcurrent requirements, while preventing the tab edges from warping and affecting the subsequent assembly process, and can also reduce the difficulty of welding, avoid welding deviation, and improve the welding yield.

[0018] In an optional implementation, a dimension D of the tab along the second direction is in the range of 30 mm ≤ D ≤ 70 mm.

[0019] Beneficial effect: By setting the dimension B0 of the tab along the second direction to be between 30 mm and 70 mm, the overcurrent requirement can be met while avoiding material waste and reducing production costs.

[0020] In an optional embodiment, the weld mark is symmetrically arranged on the pole lug along the second direction.

[0021] Beneficial effect: In the second direction, the distances from both sides of the weld mark to the edge of the tab are equal, which facilitates the positioning processing during the tab pre-welding process, improves the symmetry of the tab structure after pre-welding, is beneficial to improve the stability of the tab after pre-welding, and ensures the uniformity of current distribution on the tab during battery operation, thereby improving the stability of the current and the quality of the battery.

[0022] In a second aspect, the present invention further provides a battery pack, comprising: the above-mentioned battery. Since the battery pack comprises the battery and has the same effect as the battery, 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 A schematic diagram of the structure of a battery according to an embodiment of the present invention;

[0025] Figure 2 A schematic diagram of the structure of a pole group according to an embodiment of the present invention;

[0026] Figure 3 A schematic structural diagram of a positive electrode sheet according to an embodiment of the present invention;

[0027] Figure 4The figure is a schematic structural diagram of a negative electrode sheet according to an embodiment of the present invention.

[0028] Description of reference numerals:

[0029] 100, pole group; 110, pole group body; 120, pole ear; 1, positive electrode sheet; 101, positive electrode sheet body; 102, positive electrode ear; 2, negative electrode sheet; 201, negative electrode sheet body; 202, negative electrode ear; 3, diaphragm; 4, weld mark; 5, packaging film; 501, seal; 6, positive electrode adapter; 7, negative electrode adapter; 8, sealing component. DETAILED DESCRIPTION

[0030] 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.

[0031] Combine the following Figures 1 to 4 , describing an embodiment of the present invention.

[0032] According to an embodiment of the present invention, on the one hand, a battery is provided, including: a pole group 100, a packaging film 5 and a transfer sheet. The pole group 100 includes a pole group body 110 and a pole ear 120, wherein the pole ear 120 extends from a portion of the side of the pole group body 110 along a first direction, and the pole ear 120 is suitable for forming a weld mark 4 after the pole ear 120 is pre-welded, and the orthographic projection area of ​​the weld mark 4 on the surface of the pole ear 120 is S1, and the surface area of ​​the pole ear 120 is S2, wherein S1 and S2 satisfy the relationship: 0.18≤S1 / S2≤0.35; the packaging film 5 is coated on the outside of the pole group 100 to seal and package the pole group 100; one end of the transfer sheet is welded to the pole ear and the other end extends out of the packaging film 5. Among them, the first direction refers to Figure 2 The arrow in the middle points to the "first direction"; the units of S1 and S2 are both mm 2 .

[0033] In the battery using this embodiment, the pole tabs 120 are pre-welded, and the pole tabs on the pole pieces of the same polarity in the pole group 100 are gathered together as one, so as to realize the electrical connection between the pole pieces of the same polarity, and the integrity is good, which is convenient for the subsequent welding operation between the pole tab 120 and the adapter sheet. At the same time, by setting the area ratio S1 / S2 of the weld mark 4 formed by the pre-welding on the surface of the pole tab to be between 0.18 and 0.35, it is possible to avoid poor welding such as cold welding, blown holes, and too small welding pull-out force of the weld mark on the pole tab during the pre-welding process of the pole tab, and ensure that the weld mark 4 can meet the overcurrent requirement of the battery, and avoid abnormal conditions such as welding deviation, excessive pull-out force of the weld mark on the pole tab, and pole tab tearing, thereby improving the welding quality and the production line yield.

[0034] It should be noted that the electrode group 100 includes several layers of positive electrode sheets 1, several layers of negative electrode sheets 2 and several layers of separators 3. The positive electrode sheets 1, the negative electrode sheets 2 and the separators 3 are stacked in the order of the negative electrode sheets 2, the separators 3, the positive electrode sheets 1, the negative electrode sheets 2... to form the electrode group 100. The positive electrode sheet 1 includes a positive electrode sheet body 101 and a positive electrode ear 102 connected to the side of the positive electrode sheet body 101. The negative electrode sheet 2 includes a negative electrode sheet body 201 and a negative electrode ear 202 connected to the side of the negative electrode sheet body 201. The electrode group body 110 includes a positive electrode sheet body 101, a negative electrode sheet body 201 and a separator 3, and further combined with Figure 2 It can be seen that the size of the diaphragm 3 is larger than the size of the positive electrode sheet body 101 and the negative electrode sheet body 201. The diaphragm 3 completely covers the positive electrode sheet body 101 and the negative electrode sheet body 201 to ensure insulation between the positive electrode sheet 1 and the negative electrode sheet 2. Part of the positive electrode ear 102 of the positive electrode sheet 1 on the side close to the positive electrode sheet body 101 is covered by the diaphragm 3, and part of the negative electrode ear 202 of the negative electrode sheet 2 on the side close to the negative electrode sheet body 201 is covered by the diaphragm 3. The surface area S2 of the electrode ear 120 in this embodiment refers to the surface area of ​​the portion of the positive electrode ear 102 extending out of the area covered by the diaphragm 3 or the surface area of ​​the portion of the negative electrode ear 202 extending out of the area covered by the diaphragm 3.

[0035] The pre-welding of the pole tabs refers to welding the pole tabs of the same polarity together. The positive pole tabs 102 on a plurality of positive pole sheets 1 are connected into an integrated positive pole tab unit after the pre-welding of the pole tabs. The negative pole tabs 202 on a plurality of negative pole sheets 2 are connected into an integrated negative pole tab unit after the pre-welding of the pole tabs. A weld mark 4 is formed on each of the positive pole tab unit and the negative pole tab unit. The pole sheets of the same polarity are electrically connected through the weld mark 4. During the operation of the battery, the current flows through the weld mark 4. The size of the weld mark 4 directly affects the current carrying capacity of the pole tab. The orthographic projection area S1 of the weld mark 4 on the surface of the pole tab 120 is the current carrying area of ​​the weld mark 4. S1 is equal to the surface area S of the pole tab 120. 2 is the ratio S1 / S2 of the weld mark 4 formed by pre-welding on the surface of the lug 120. If S1 / S2 is less than 0.18, the weld mark 4 accounts for too small a proportion of the lug surface, and poor welding such as cold welding, blown holes, and too small welding pull-out force of the weld mark on the lug is prone to occur during the lug pre-welding process. The weld mark 4 serves as a current channel between different layers of pole pieces with the same polarity. If S1 is too small, the flow area at the weld mark 4 will be too small, making it difficult to meet the overcurrent requirements of the battery. If S1 / S2 is greater than 0.35, the weld mark 4 accounts for too large a proportion of the lug surface, and abnormalities such as welding deviation, excessive pull-out force of the weld mark on the lug, and lug tearing are prone to occur.

[0036] Preferably, the electrode group 100 has electrode ears on both sides, and further combined Figure 2 As shown, a pole lug 120 is connected to each of the two sides of the pole group body 110 along the first direction, and one of the two pole lugs 120 corresponds to the positive pole lug 102 and the other corresponds to the negative pole lug 202 .

[0037] Specifically, the packaging film 5 includes an upper packaging film and a lower packaging film, one of the upper packaging film and the lower packaging film is formed with a pit corresponding to the pole group 100, the pole group 100 is located in the pit, and 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 pole group 100.

[0038] Preferably, the battery is a soft-pack battery, and 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, etc.

[0039] In one embodiment, a seal 8 is provided between the adapter and the packaging film 5, and the section of the seal 501 corresponding to the adapter is pressed on the seal 8 to improve the sealing between the packaging film 5 and the adapter and ensure the safety of the battery. Preferably, the seal 8 is a sealant, which has a strong bond and good sealing performance.

[0040] Specifically, the adapter plate includes a positive adapter plate 6 and a negative adapter plate 7. The positive adapter plate 6 and the negative adapter plate 7 are respectively welded to a pole ear 120, so as to realize the separate lead-out of the positive and negative electrodes of the battery.

[0041] In one embodiment, the tab 120 is rectangular, the tab 120 is a first rectangle, the positive projection of the weld mark 4 on the surface of the tab 120 is a rectangle, the positive projection of the weld mark 4 on the surface of the tab 120 is a second rectangle, the short side of the first rectangle and the short side of the second rectangle are parallel to the first direction, the long side of the first rectangle and the long side of the second rectangle are parallel to the second direction, wherein the second direction is perpendicular to the first direction. The first direction refers to Figure 2 The arrow in the middle refers to the "first direction", and the second direction refers to Figure 2 The middle arrow indicates the "second direction". By setting the tab 120 and the positive projection of the weld mark 4 on the tab 120 to be rectangular, the rectangular structure is easy to process and shape, and is also easy to control the size, which is conducive to achieving standardization in the battery production process, improving processing accuracy, and ensuring production quality.

[0042] In one embodiment, the size of the weld mark 4 along the first direction is A, and in the first direction, the vertical distance between the side of the pole ear 120 away from the pole group body 110 and the pole group body 110 is C; wherein 0.3≤A / C≤1 / 2, and the units of A and C are both mm. If A / C is less than 0.3, then in the first direction, the size of the weld mark 4 is too small relative to the size of the pole lug 120, the flow area of ​​the weld mark 4 is insufficient, and the flow requirement cannot be met. The processing is difficult, and the weld mark 4 is too far from the edge of the pole lug 120. The weld mark 4 cannot well press the different layers of the pole lug 120, causing the edge of the pole lug 120 away from the pole group body 110 to warp, making it inconvenient for the subsequent welding of the pole lug 120 and the adapter, or the part of the pole lug 120 close to the pole group body 110 is prone to tearing; if A / C is greater than 1 / 2, then in the first direction, the size of the weld mark 4 is too large relative to the size of the pole lug 120, and the weld mark 4 is too close to the diaphragm 3. During the pre-welding process of the pole lug, the welding equipment is likely to damage the diaphragm, and it will increase the difficulty of welding, resulting in a decrease in welding quality. Therefore, by setting the ratio A / C between the dimension A of the weld mark 4 along the first direction and the vertical distance C between the side of the pole lug 120 away from the pole group body 110 and the pole group body 110 to be between 0.3 and 1 / 2, on the basis of meeting the overcurrent requirements, it is convenient to carry out the pole lug pre-welding process, while avoiding the edge of the pole lug 120 from warping or the pole lug from tearing, and can also avoid damage to the diaphragm 3 during the welding process, thereby ensuring the welding quality and improving the welding yield.

[0043] In one embodiment, the size of the weld mark 4 along the second direction is B, and the size of the tab 120 along the second direction is D, wherein 0.5≤B / D≤0.8, and the units of B and D are both mm. If B / D is less than 0.5, then in the second direction, the size of the weld mark 4 is too small for the size of the tab 120, the flow area of ​​the weld mark 4 is insufficient, and the flow requirement cannot be met, and the weld mark 4 is too far away from the edge of the tab along the second direction, causing the edges of the tab 120 on both sides of the second direction to be easily warped, affecting subsequent assembly; if B / D is greater than 0.8, then in the second direction, the size of the weld mark 4 is too small for the size of the tab 120, and the weld mark 4 is too close to the edge of the tab 120 along the second direction, which will increase the difficulty of positioning the welding tooling, and it is easy to weld off-center, resulting in poor welding. Therefore, by setting the ratio between the dimension B of the weld mark 4 along the second direction and the dimension D of the tab 120 along the second direction within the range of 0.5 to 0.8, on the basis of meeting the overcurrent requirements, it is possible to avoid the edge of the tab 120 from warping and affecting the subsequent assembly process, and it is also possible to reduce the welding difficulty, avoid welding deviation, and improve the welding yield.

[0044] It should be noted that the orthographic projection of the weld mark 4 on the surface of the pole lug 120 is rectangular, and the orthographic projection area S1 of the weld mark 4 on the surface of the pole lug 120 and the dimension A of the weld mark 4 along the first direction and the dimension B of the weld mark 4 along the second direction satisfy the relationship: S1=A×B; the pole lug 120 is rectangular, and the surface area S2 of the pole lug and the vertical distance C between the side of the pole lug 120 away from the pole group body 110 and the pole group body 110 and the dimension D of the pole lug along the second direction satisfy the relationship: S2=C×D.

[0045] In one embodiment, the value range of the dimension A of the weld mark 4 along the first direction is: 3mm≤A≤5mm. It should be noted that the weld mark 4 is the actual flow area between the pole pieces of the same polarity, and the size of the weld mark 4 directly affects the flow capacity of the entire battery. If the dimension A of the weld mark 4 along the first direction is less than 3mm, the width dimension of the weld mark 4 along the first direction is too small, and the processing difficulty is relatively large. In addition, since the size of the flow area of ​​the weld mark 4 depends on the dimension A of the weld mark 4 along the first direction and the dimension B of the weld mark 4 along the second direction, and the value range of B is certain, if A is too small, even if B takes a larger value within the limited range, the flow area of ​​the entire weld mark 4 is still small, and it is difficult to meet the flow demand. If A is greater than 5mm, the width dimension of the weld mark 4 along the first direction is too large, and the weld mark 4 is too close to the diaphragm 3. During the pre-welding process of the tab, the welding equipment is easy to damage the diaphragm, and it will increase the difficulty of welding, resulting in a decrease in welding quality. Therefore, by setting the dimension A of the weld mark 4 along the first direction to be in the range of 3 mm to 5 mm, it is easy to process, can meet the overcurrent requirements, avoid damage to the diaphragm 3 during welding, reduce welding difficulty, ensure welding quality, and improve welding yield.

[0046] In one embodiment, in the first direction, the vertical distance C between the side of the pole tab 120 away from the pole group body 110 and the pole group body 110 is in the range of 8 mm ≤ C ≤ 15 mm. It should be noted that the size of the diaphragm 3 along the first direction is greater than the size of the positive electrode sheet 1 and the negative electrode sheet 2 along the first direction, and the vertical distance C between the side of the pole tab 120 away from the pole group body 110 and the pole group body 110 refers to the vertical distance from the side of the pole tab 120 away from the pole group body 110 to the side of the diaphragm 3, that is, the width of the pole tab 120 along the first direction. If the dimension C of the pole tab 120 along the first direction is less than 8 mm, the size of the pole tab 120 is too small, and it cannot provide enough welding space for the weld mark 4. The processing difficulty of the pole tab pre-welding process is relatively large, and it is difficult to meet the overcurrent requirement. If C is greater than 15 mm, the size of the pole tab 120 along the first direction is too large, which wastes materials, and the size of the remaining area of ​​the pole tab 120 except the weld mark 4 along the first direction is too large, and the different layers of the pole tab 120 are relatively scattered, which is easy to tear. Therefore, by limiting the vertical distance C between the side of the pole tab 120 away from the pole group body 110 and the pole group body 110 to a value within the range of 8 mm to 15 mm, the size of the pole tab 120 is limited to a reasonable range, which can not only ensure that the pole tab 120 meets the overcurrent requirement and reduce the processing difficulty, but also avoid the tearing of the pole tab, improve the battery qualification rate, and save materials and control costs at the same time.

[0047] In one embodiment, the dimension of the weld mark 4 along the second direction is B, where 20mm≤B≤50mm. If B is less than 20mm, the dimension B of the weld mark 4 along the second direction is too small. Even if the dimension A of the weld mark 4 along the first direction takes a larger value within its value range, the flow area of ​​the entire weld mark 4 is still small, which is difficult to meet the flow demand. The weld mark 4 is too far away from the edge of the pole ear along the second direction, which may cause the edge of the pole ear to be easily warped. If B is greater than 50mm, the dimension of the weld mark 4 along the second direction is too large, which may cause the weld mark 4 to be too close to the edge of the pole ear 120 along the second direction, increase the positioning difficulty of the welding tool, and easily cause welding deviation, resulting in poor welding. Therefore, by setting the dimension B of the weld mark 4 along the second direction to take a value within the range of 20mm to 50mm, it can not only ensure that the pole ear 120 meets the flow requirement, but also avoid the edge of the pole ear 120 from warping and affecting the subsequent assembly process, but also reduce the welding difficulty, avoid welding deviation, and improve the welding yield.

[0048] In one embodiment, the dimension D of the tab 120 along the second direction has a value range of: 30mm≤D≤70mm. The dimension of the tab 120 along the second direction is the length of the tab 120. If the dimension B0 of the tab 120 along the second direction is less than 30mm, the length of the tab 120 is too short, and the tab 120 cannot reserve enough space for the pre-welding weld mark 4 in the second direction, resulting in the size of the weld mark 4 along the second direction being too small, making it difficult to meet the overcurrent requirement, or causing the pre-welding weld mark 4 to be too close to the edge of the tab 120 in the second direction, which is prone to poor welding such as cold welding and welding slag, thereby affecting the overcurrent capacity of the tab 120; if B0 is greater than 70mm, the length of the tab 120 is too long, too much material is used, the production cost is high, and the processing is inconvenient. Therefore, by setting the dimension B0 of the tab 120 along the second direction to be between 30mm and 70mm, it is possible to meet the overcurrent requirement, avoid wasting materials, and reduce production costs.

[0049] In one embodiment, the weld mark 4 is symmetrically arranged in the center of the pole lug 120 along the second direction. In the second direction, the distances from both sides of the weld mark 4 to the edge of the pole lug 120 are equal, which is convenient for positioning processing during the pre-welding process of the pole lug, improves the symmetry of the structure of the pole lug 120 after pre-welding, is beneficial to improving the stability of the pole lug 120 after pre-welding, and ensures the uniformity of current distribution on the pole lug 120 during battery operation, thereby improving the stability of the current and the quality of the battery.

[0050] The battery of this embodiment reasonably optimizes and defines the pre-welding process parameters of the tab 120 , thereby improving the pre-welding yield and quality of the tab 120 .

[0051] According to the above formula S1 = A × B, S2 = C × D and the value ranges of A, B, C, and D, it can be concluded that the value range of S1 is 60 mm 2 ≤S1≤250mm 2 , S2 value range is 240mm 2 ≤S1≤1050mm 2 .

[0052] The following describes the experimental results of testing cells with different parameter values ​​to experimentally verify the parameter values ​​of the cell.

[0053] Table 1 Cell verification results corresponding to different parameter values

[0054]

[0055] It can be seen from Table 1 that for the battery cells of Implementation Case 1 to Implementation Case 6, the area ratio S1 / S2 of the weld mark 4 formed by pre-welding on the surface of the pole ear is within the range of 0.18 to 0.35 specified in the present application, the ratio A / C between the dimension A of the weld mark 4 along the first direction and the vertical distance C between the side of the pole ear 120 away from the pole group body 110 and the pole group body 110 is within the range of 0.3 to 1 / 2 specified in the present application, and the ratio B / D between the dimension B of the weld mark 4 along the second direction and the dimension D of the pole ear 120 along the second direction is within the range of 0.5 to 0.8 specified in the present application. The experimental verification results show that the battery cells of Implementation Case 1 to Implementation Case 6 can meet the overcurrent requirements, and there is no tearing of the pole ear or warping of the edge of the pole ear, the positioning difficulty of the welding tooling is small, there is no welding deviation or diaphragm damage, and the welding yield is high. For the battery cells of comparative case 1, S1 / S2 is less than 0.18, A / C is less than 0.3, and B / D is less than 0.5, all of which are not within the range specified in the present application, and the overcurrent requirements are not met. In addition, the tabs are torn or the edges of the tabs are lifted, and the welding yield is low; for the battery cells of comparative case 2, S1 / S2 is greater than 0.35, A / C is greater than 1 / 2, and B / D is greater than 0.8, all of which are not within the range specified in the present application. Although the overcurrent requirements can be met, the positioning of the welding tooling is difficult, welding deviation, diaphragm damage, and tab tearing occur, and the welding yield is low; for the battery cells of comparative case 3, S1 / S2 is greater than 0.35 and A / C is greater than 1 / 2, which are not within the range specified in the present application. Although the overcurrent requirements are met, welding is difficult, diaphragm damage and tab tearing occur, and the welding yield is low.

[0056] In summary, by limiting S1 / S2 to be in the range of 0.18 to 0.35, A / C to be in the range of 0.3 to 1 / 2, and B / D to be in the range of 0.5 to 0.8, it is ensured that the weld mark 4 provides sufficient flow area for the tab to meet the flow requirements. At the same time, it can avoid the tab tearing or the edge warping of the tab 120 during the pre-welding process of the tab, reduce the difficulty of positioning the welding tooling, reduce the difficulty of welding, avoid damaging the diaphragm 3 during welding, avoid welding deviation, and avoid excessive pulling force of the weld mark on the tab, thereby ensuring the welding quality and improving the welding yield.

[0057] According to an embodiment of the present invention, on the other hand, a battery pack is provided, comprising: the above-mentioned battery.

[0058] 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, characterized in that: include: A pole group, comprising a pole group body and a pole ear, wherein the pole ear extends from a part of a side area of ​​the pole group body along a first direction, and the pole ear is suitable for forming a weld mark on the pole ear after pre-welding, the orthographic projection area of ​​the weld mark on the surface of the pole ear is S1, and the surface area of ​​the pole ear is S2, wherein S1 and S2 satisfy the relationship: 0.18≤S1 / S2≤0.35; A packaging film, covering the outside of the electrode group to seal and package the electrode group; A transfer plate, one end of which is welded to the pole ear and the other end of which extends out of the packaging film.

2. The battery according to claim 1, characterized in that The pole ear is rectangular, the rectangle of the pole ear is a first rectangle, the orthographic projection of the weld mark on the surface of the pole ear is a rectangle, the orthographic projection of the weld mark on the surface of the pole ear is a second rectangle, the short side of the first rectangle and the short side of the second rectangle are both parallel to the first direction, the long side of the first rectangle and the long side of the second rectangle are both parallel to the second direction, wherein the second direction is perpendicular to the first direction.

3. The battery according to claim 2, characterized in that The size of the weld mark along the first direction is A; in the first direction, the vertical distance between the side of the pole ear away from the pole group body and the pole group body is C; wherein 0.3≤A / C≤1 / 2.

4. The battery according to claim 3, characterized in that The value range of the dimension A of the weld mark along the first direction is: 3mm≤A≤5mm.

5. The battery according to claim 3, characterized in that In the first direction, a vertical distance C between a side of the pole lug away from the pole group body and the pole group body is in the range of 8 mm ≤ C ≤ 15 mm.

6. The battery according to claim 2, characterized in that The size of the weld mark along the second direction is B, and the size of the tab along the second direction is D, wherein 0.5≤B / D≤0.

8.

7. The battery according to claim 6, characterized in that The value range of the dimension B of the weld mark along the second direction is: 20mm≤B≤50mm.

8. The battery according to claim 6, characterized in that The dimension D of the tab along the second direction has a value range of 30 mm ≤ D ≤ 70 mm.

9. The battery according to any one of claims 2 to 8, characterized in that The weld marks are symmetrically arranged on the pole lug along the second direction.

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

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