Battery cell, battery pack and vehicle

Abstract

The invention provides a battery cell, a battery pack and a vehicle, and the battery cell comprises a roll core which is provided with a tab; the cover plate assembly comprises a pole, a connecting hole is formed in the end wall, facing the roll core, of the pole, and at least part of the tab penetrates into the connecting hole and is in conductive connection with the pole. According to the invention, the tab directly penetrates through the pole and does not need to be connected with the pole after being bent, so that the height space occupation of the tab is reduced, the height space utilization rate of the battery cell is improved, the height of the roll core can be improved, and the volume energy density of the battery cell is improved; the tabs directly penetrate through the pole columns, so that an insulating partition plate can be omitted, the number of structural parts in the battery cell is reduced, the cost and the weight of the structural parts of the battery cell are reduced, and the weight energy density of the battery cell is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power batteries, in particular to a battery cell, a battery pack and a vehicle. BACKGROUND

[0002] In the related art battery cell structure, the tab is bent and welded at the bottom of the pole, but as the thickness of the lithium battery becomes larger and larger, the number of layers of the tab sheet becomes more and more, the thickness of the tab increases, and the space required for the tab bending also increases, resulting in a loss of battery cell capacity. Moreover, in order to avoid the risk of the tab being inserted into the diaphragm of the roll core, causing internal short circuit, an insulating separator is usually added between the roll core and the tab to isolate the roll core and the tab, but the insulating separator also wastes the height space of the battery cell. SUMMARY

[0003] The purpose of the present application is to provide a battery cell, a battery pack and a vehicle to improve the height space utilization of the battery cell.

[0004] To solve the above technical problems, the present application provides a battery cell, comprising:

[0005] a roll core, the roll core being provided with a tab;

[0006] a cover plate assembly comprising a pole, the pole being provided with a connecting hole facing the end wall of the roll core, at least part of the tab penetrating into the connecting hole and being in conductive connection with the pole.

[0007] The present application optimizes the connection mode of the conventional tab and the pole, at least part of the tab penetrating into the interior of the connecting hole of the pole and being in conductive connection with the pole. The tab does not need to be connected with the pole after the bending process, reducing the occupation of the height space of the tab, improving the height space utilization of the battery cell, and improving the height of the roll core under the condition that the internal accommodation space of the shell of the battery cell is unchanged, improving the volumetric energy density of the battery cell. In theory, the volumetric energy density of each battery cell can be improved by 1%~3%. At the same time, the tab is directly penetrated in the pole, the insulating separator can be cancelled, the number of structural parts in the battery cell is reduced, the cost and weight of the structural parts of the battery cell are reduced, according to the conventional structural part thickness and size design, in theory, each battery cell can reduce the weight by 4g~20g, improving the weight energy density of the battery cell.

[0008] The present application also provides a battery pack comprising the aforementioned battery cell.

[0009] The battery pack of the present application comprises the aforementioned battery cell, and therefore has the same technical effects as the aforementioned battery cell, which will not be described here again.

[0010] The present application also provides a vehicle comprising the aforementioned battery pack.

[0011] The vehicle of the present application comprises the aforementioned battery pack, and thus has the same technical effects as the aforementioned battery pack, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 A first specific embodiment of the battery cell provided by the present application is shown in a cross-sectional view in the height direction;

[0013] Figure 2 A second specific embodiment of the battery cell provided by the present application is shown in a partial cross-sectional view in the height direction; Figure 1

[0014] Figure 3 A third specific embodiment of the battery cell provided by the present application is shown in a partial cross-sectional view in the height direction;

[0015] Figure 4 A fourth specific embodiment of the battery cell provided by the present application is shown in a partial cross-sectional view in the height direction;

[0016] Figure 5 A fifth specific embodiment of the battery cell provided by the present application is shown in a partial cross-sectional view in the height direction;

[0017] Figure 6 A structure schematic diagram of the jelly-roll in the battery cell provided by the present application is shown;

[0018] Figure 7 A top view of the cover plate assembly in the battery cell provided by the present application is shown;

[0019] Figure 8 A top view of the cover plate assembly in the battery cell provided by the present application is shown;

[0020] Figure 9 A partial enlarged view of the cover plate assembly is shown; Figure 8

[0021] Figure 10 A partial bottom view of the cover plate assembly in the battery cell provided by the present application is shown;

[0022] Figure 11 A structure schematic diagram of the pole in some embodiments of the battery cell provided by the present application is shown;

[0023] Figure 12 A structure schematic diagram of the pole in some other embodiments of the battery cell provided by the present application is shown;

[0024] In the drawings, Figures 1-12 The reference signs in the drawings are as follows:

[0025] 1 - jelly-roll; 11 - tab; a1 - flat section; a2 - bent section;

[0026] 2 - cover plate assembly; 21 - pole; 21a - connecting hole; 21b - welding hole; 22 - light aluminum sheet; 22a - liquid injection port; ​​

[0027] 3 - auxiliary welding sheet; 3a - notch part;

[0028] a - limiting part; b - limiting matching part. DETAILED DESCRIPTION

[0029] In order to make the technical personnel in the art better understand the technical solutions of the present application, the present application will be further described in detail below in combination with the drawings and specific embodiments.

[0030] Please refer to Figures 1-4 , Figure 1 is a first specific embodiment of the battery provided by the present application in the height direction; Figure 2 is Figure 1 is a local enlarged view of the battery in the A area; Figure 3 is a second specific embodiment of the battery provided by the present application in the height direction; Figure 4 is a third specific embodiment of the battery provided by the present application in the height direction.

[0031] The present embodiment provides a battery, comprising:

[0032] The winding core 1 is provided with a tab 11.

[0033] The cover plate assembly 2 comprises a pole 21, the pole 21 is provided with a connecting hole 21a facing the end wall of the winding core 1, at least part of the tab 11 penetrates into the connecting hole 21a and is in conductive connection with the pole 21.

[0034] The battery of the present embodiment optimizes the connection mode of the traditional tab and the pole, at least part of the tab 11 penetrates into the inside of the connecting hole 21a of the pole 21, realizing the conductive connection between the tab 11 and the pole 21, the tab 11 does not need to be connected with the bottom of the pole 21 after the bending process, reducing the occupation of the height space of the tab 11, improving the height space utilization rate of the battery, under the condition that the internal accommodation space of the shell of the battery is unchanged, the height of the winding core 1 can be improved, improving the volume energy density of the battery, theoretically, the volume energy density of each battery can be improved by 1%~3%; at the same time, the tab 11 is directly penetrated in the pole 21, the insulating partition can be cancelled, reducing the number of structural parts in the battery, reducing the cost and weight of the structural parts of the battery, according to the conventional structural part thickness and size design, theoretically, each battery can reduce the weight by 4g~20g, improving the weight energy density of the battery.

[0035] Among them, the tab 11 and the pole 21 are in conductive connection, usually the tab 11 and the pole 21 are welded to realize the conductive connection between the two, the tab 11 and the pole 21 can specifically adopt laser welding or ultrasonic welding.

[0036] At least part of the tab 11 penetrates into the connecting hole 21a, and in some embodiments, the tab 11 penetrates into the inside of the connecting hole 31a. In other embodiments, the end of the tab 11 away from the winding core 1 penetrates into the inside of the connecting hole 21a, and the end of the tab 11 close to the winding core 1 is located inside the shell of the battery cell.

[0037] It can be understood that in practice, the winding core 1 is provided with positive and negative tabs, and the cover plate assembly 2 includes positive and negative poles, the positive tab is connected to the positive pole, and the negative tab is connected to the negative pole, and the connection structures of the positive tab and the positive pole and the connection structures of the negative tab and the negative pole are consistent. Therefore, the positive and negative poles are not distinguished here.

[0038] As shown in Figure 2 and Figure 3 , in this embodiment, the cover plate assembly 2 further includes:

[0039] An auxiliary welding sheet 3 is provided, which is at least partially attached to the side surface of the tab 11 and electrically connected thereto. At least part of the auxiliary welding sheet 3 penetrates into the connecting hole 21a and is electrically connected to the pole 21.

[0040] Since the material of the tab 11 is usually soft, it is difficult for the tab 11 to penetrate into the connecting hole 21a, and it is also difficult for the tab 11 to be directly welded to the pole 21. Based on this, some embodiments of the present application add an auxiliary welding sheet 3, which is connected to the tab 11 in advance. The auxiliary welding sheet 3 can play a supporting role, so that the overall structural strength is improved, and the auxiliary welding sheet 3 and the tab 11 are more easily inserted into the inside of the connecting hole 21a. Then, the auxiliary welding sheet 3 and the pole 21 are welded, the auxiliary welding sheet 3 and the pole 21 can be more stably attached, reducing the welding difficulty and improving the electrical connection reliability of the auxiliary welding sheet 3 and the pole 21.

[0041] In practice, the auxiliary welding sheet 3 and the tab 11 can be fixed together by ultrasonic welding.

[0042] As shown in Figure 2 , in this embodiment, the tab 11 extends along the direction of the hole axis of the connecting hole 21a.

[0043] As arranged above, the tab 11 is directly inserted into the connecting hole 21a, and the length of the tab 11 is as short as possible, which can reduce the transmission path of the tab current and reduce the connection impedance of the tab 11.

[0044] As can be seen, Figure 2In the shown embodiment, the electric core further comprises an auxiliary welding tab 3 extending along the direction of the hole axis of the connecting hole 21a, the auxiliary welding tab 3 is in contact with and electrically connected to the side surface of the tab 11, and the end surface of the auxiliary welding tab 3 away from the winding core 1 and the end wall of the connecting hole 21a can be stably in contact, the welding difficulty is low, the electrically conductive connection between the tab 11 and the pole 21 is realized through the auxiliary welding tab 3, and the reliability of the electrically conductive connection between the tab 11 and the pole 21 is ensured.

[0045] As mentioned above, the auxiliary welding tab 3 is at least partially in contact with the side surface of the tab 11. In some embodiments, the auxiliary welding tab 3 is in contact with the entire side surface of the tab 11. Figure 3 In the shown embodiment, the auxiliary welding tab 3 is in contact with the entire side surface of the tab 11. In some other embodiments, the auxiliary welding tab 3 is partially in contact with the side surface of the tab 11, and the end of the auxiliary welding tab 3 away from the winding core 1 is closer to the pole 21 than the end of the tab 11 away from the winding core 1, and in the connected state, the end of the tab 11 away from the winding core 1 has a spacing from the end wall of the connecting hole 21a.

[0046] As mentioned above, the auxiliary welding tab 3 is at least partially in contact with the side surface of the tab 11. In some embodiments, the auxiliary welding tab 3 is in contact with the entire side surface of the tab 11. Figure 4 In the shown embodiment, the tab 11 comprises a straight section a1 and a bent section a2, the straight section a1 extends along the direction of the hole axis of the connecting hole 21a, and the bent section a2 extends along the transverse direction of the connecting hole 21a, and the bent section a2 is electrically connected to the pole 21.

[0047] As arranged above, the bent section a2 is in contact with and electrically connected to the side surface of the winding core 1 and the closed end wall of the connecting hole 21a, which significantly increases the welding area of the tab 11 and the pole 21, on the one hand, can improve the welding strength of the tab 11 and the pole 21, and ensure the reliability of the electrically conductive connection between the tab 11 and the pole 21, and on the other hand, can improve the overcurrent capacity of the electric core, and meet the fast charging design requirements.

[0048] As can be seen in the shown embodiment, the bent section a2 is in contact with and electrically connected to the side surface of the winding core 1 and the end wall of the connecting hole 21a, which significantly increases the welding area of the tab 11 and the pole 21, on the one hand, can improve the welding strength of the tab 11 and the pole 21, and ensure the reliability of the electrically conductive connection between the tab 11 and the pole 21, and on the other hand, can improve the overcurrent capacity of the electric core, and meet the fast charging design requirements. Figure 4 As can be seen in the shown embodiment, the bent section a2 is in contact with and electrically connected to the side surface of the winding core 1 and the end wall of the connecting hole 21a, which significantly increases the welding area of the tab 11 and the pole 21, on the one hand, can improve the welding strength of the tab 11 and the pole 21, and ensure the reliability of the electrically conductive connection between the tab 11 and the pole 21, and on the other hand, can improve the overcurrent capacity of the electric core, and meet the fast charging design requirements.

[0049] Figure 3 In the shown embodiment, the auxiliary welding tab 3 is connected to the side surface of the bent section a2 away from the winding core 1, and the side surface of the auxiliary welding tab 3 away from the winding core 1 and the end wall of the connecting hole 21a can be more stably in contact, further reducing the welding difficulty, and improving the reliability of the electrically conductive connection between the tab 11 and the pole 21.

[0050] As mentioned above, the auxiliary welding tab 3 is at least partially in contact with the side surface of the tab 11. In some embodiments, the auxiliary welding tab 3 is in contact with the entire side surface of the tab 11. Figure 3 ​In the shown embodiment, the auxiliary welding tab 3 entirely adheres to the side of the bending section a2 away from the core 1. In other embodiments, the auxiliary welding tab 3 has a width greater than that of the bending section a2, and the auxiliary welding tab 3 partially adheres to the side of the bending section a2 away from the core 1.

[0051] Further, in Figure 2 In the shown embodiment, the width of the connecting hole 21a ranges from 1mm to 20mm, and the width of the connecting hole 21a is defined as D1, and the value of D1 ranges from 1mm to 20mm.

[0052] It can be understood that, in order to ensure that the auxiliary welding tab 3 and the tab 11 can be kept in a stable state after being inserted into the connecting hole 21a, and to ensure that the auxiliary welding tab 3 can be accurately connected at the preset position, the sum of the thicknesses of the auxiliary welding tab 3 and the tab 11 is slightly less than or equivalent to the width of the connecting hole 21a. It has been verified that when the width of the connecting hole 21a is greater than 20mm, the structural strength of the pole 21 is obviously weakened, and the pole 21 has the possibility of cracking under high pressure, or in order to ensure the structural strength of the pole 21, the size of the pole 21 needs to be increased, resulting in an increase in the weight and cost of the core; when the width of the connecting hole 21a is less than 1mm, the space for accommodating the auxiliary welding tab 3 is very small in addition to the space for accommodating the tab 11, the thickness of the auxiliary welding tab 3 is very thin, the welding area of the auxiliary welding tab 3 and the pole 21 is small, and the reliability of the conductive connection between the auxiliary welding tab 3 and the pole 21 cannot be guaranteed. Based on this, in the present embodiment, the width of the connecting hole 21a has the above value range, which can ensure the reliability of the conductive connection between the auxiliary welding tab 3 and the pole 21, and reduce the weight and cost of the core 1.

[0053] In practice, D1 can have values of 1mm, 10mm, 15mm, 20mm, etc. When D1 is 1mm, the thickness of the auxiliary welding tab 3 is as thin as possible under the premise of ensuring the reliability of the conductive connection between the auxiliary welding tab 3 and the pole 21, thereby reducing the structural cost and the weight of the core. When D1 is 20mm, the welding area of the auxiliary welding tab 3 and the pole 21 is the largest under the premise that the structural cost and the weight of the core meet the requirements, thereby improving the reliability of the conductive connection between the auxiliary welding tab 3 and the pole 21 as much as possible, improving the overcurrent capacity of the core, and meeting the fast charging design requirements. When D1 is 10mm or 15mm, a balance can be achieved among the structural cost, the weight of the core, and the reliability of the conductive connection, thereby improving the overall quality of the core.

[0054] From Figure 2As can be seen, in this embodiment, there is a gap between the side wall of the tab 11 facing away from the welding piece 3 and the relative inner side wall of the connecting hole 21a. It can be understood that since the tab 11 is formed by stacking tab pieces that are brought together, the thickness of the tab 11 varies depending on the number of tab pieces. The gap between the side wall of the tab 11 facing away from the welding piece 3 and the relative inner side wall of the connecting hole 21a allows for a certain amount of clearance inside the connecting hole 21a, ensuring that even if the thickness of the tab 11 varies, the tab 11 and the auxiliary welding piece 3 can be smoothly inserted into the connecting hole 21a.

[0055] Depend on Figure 3 As can be seen, in this embodiment, there is a gap between the side wall of the straight section a1 facing away from the bent section a2 and the relative inner side wall of the connecting hole 21a.

[0056] Similarly, since the tab 11 is formed by stacking tab pieces that are brought together, the thickness of the tab 11 is different depending on the number of tab pieces. There is a gap between the side wall of the straight section a1 facing away from the bent section a2 and the relative inner side wall of the connecting hole 21a. That is, a certain amount of allowance is reserved inside the connecting hole 21a to ensure that even if the thickness of the tab 11 is different, the tab 11 and the auxiliary welding piece 3 can be smoothly inserted into the connecting hole 21a.

[0057] Furthermore, in Figure 3 In the embodiments, the width of the connecting hole 21a ranges from 3mm to 20mm.

[0058] It is understandable that, in order to ensure the stability of the auxiliary welding piece 3 and the electrode tab 11 after they are inserted into the connecting hole 21a, and to ensure that the auxiliary welding piece 3 can be accurately connected in the preset position, the width of the auxiliary welding piece 3 is slightly smaller than the width of the connecting hole 21a, or is equivalent to the width of the connecting hole 21a. Verification has shown that when the width of the connecting hole 21a is greater than 20mm, the structural strength of the electrode post 21 is significantly weakened, and the electrode post 21 may crack under high pressure. Alternatively, to ensure the structural strength of the electrode post 21, its size needs to be increased, leading to increased weight and cost of the battery cell. When the width of the connecting hole 21a is less than 3mm, the width of the auxiliary welding piece 3 is limited, the welding area between the auxiliary welding piece 3 and the bending section a2 is small, and the reliability of the conductive connection between the auxiliary welding piece 3 and the bending section a2 cannot be guaranteed. Therefore, in this embodiment, the width of the connecting hole 21a has the above-mentioned range, which can both ensure the reliability of the conductive connection between the auxiliary welding piece 3 and the bending section a2 and reduce the weight and cost of the core 1.

[0059] In practice, D1 can be 3 mm, 10 mm, 15 mm, 20 mm, etc. When D1 is 3 mm, the thickness of the auxiliary welding piece 3 is as thin as possible under the premise of ensuring the reliable conductive connection of the auxiliary welding piece 3 and the bending section a2, the size of the pole 21 is reduced, the structural cost is reduced, and the weight of the battery cell is reduced. When D1 is 20 mm, under the premise that the structural cost and the weight of the battery cell meet the requirements, the welding area of the auxiliary welding piece 3 and the bending section a2 is the largest, the reliable conductive connection of the auxiliary welding piece 3 and the bending section a2 is improved as much as possible, the overcurrent capacity of the battery cell is improved, the fast charging design requirement is met, and the comprehensive quality of the battery cell is improved.

[0060] Further, in the embodiment of the application, the width of the connecting hole 21a is 3 mm to 20 mm. Figure 4

[0061] It can be understood that, in order to ensure that the pole tab 11 can remain in a stable state after being inserted into the connecting hole 21a and ensure that the bending section a2 can be accurately connected at the preset position, the width of the bending section a2 is slightly smaller than or equivalent to the width of the connecting hole 21a. It has been verified that when the width of the connecting hole 21a is greater than 20 mm, the structural strength of the pole 21 is obviously weakened, the pole 21 has a possibility of cracking under high air pressure, or in order to ensure the structural strength of the pole 21, the size of the pole 21 needs to be increased, resulting in an increase in the weight and cost of the battery cell. When the width of the connecting hole 21a is less than 3 mm, the fitting area of the bending section a2 and the pole 21 is small, and the reliable conductive connection of the bending section a2 and the pole 21 cannot be ensured. Therefore, in the embodiment, the width of the connecting hole 21a has the above range, which can ensure the reliable conductive connection of the bending section a2 and the pole 21 and reduce the weight and cost of the battery cell.

[0062] In practice, the width of the connecting hole 21a can be 3 mm, 10 mm, 15 mm, 20 mm, etc. When the width of the connecting hole 21a is 3 mm, the structural strength of the pole 21 is the largest under the premise of ensuring the reliable conductive connection of the bending section a2 and the pole 21, the possibility of cracking of the pole 21 under high air pressure is minimized, and the size of the pole 21 is reduced, the structural cost is reduced, and the weight of the battery cell is reduced. When the width of the connecting hole 21a is 20 mm, under the premise that the structural strength of the pole 21 and the cost and weight of the battery cell meet the requirements, the welding area of the bending section a2 and the pole 21 is the largest, the reliable conductive connection of the bending section a2 and the pole 21 is improved as much as possible, the overcurrent capacity of the battery cell is improved, the fast charging design requirement is met, and the comprehensive quality of the battery cell is improved.​

[0063] In addition, Figure 3 In the illustrated embodiment, the width of the auxiliary welding piece 3 is slightly smaller than the width of the connecting hole 21a, reducing the difficulty of inserting the auxiliary welding piece 3 into the connecting hole 21a. Alternatively, in some other embodiments of this application, the auxiliary welding piece 3 and the connecting hole 21a have a zero-clearance fit.

[0064] In some embodiments of this application, the tab 11 and the post 21 are connected by laser penetration welding, such as... Figure 4 As shown; in other embodiments of this application, the auxiliary welding piece 3 and the electrode post 21 are connected by laser penetration welding, thereby achieving a conductive connection between the tab 11 and the electrode post 21, as shown. Figure 2 and Figure 3 As shown.

[0065] Thus, after the assembly of the core 1 and the cover plate assembly 2 is completed, the tab 11 and the pole post 21, or the auxiliary welding piece 3 and the pole post 21, can be welded and fixed directly on the outside of the cell, which is convenient to operate.

[0066] Please continue to refer to this. Figures 1-4 In some embodiments of this application, the end wall of the pole post 21 facing away from the winding core 1 is provided with a welding hole 21b. Figure 1 , Figure 3 and Figure 4 In the illustrated embodiment, the width of the welding hole 21b is greater than the width of the connecting hole 21a. Within the transverse projection plane of the pole post 21, the projection area of ​​the connecting hole 21a is located inside the projection area of ​​the welding hole 21b. Figure 2 In the illustrated embodiment, the width of the welding hole 21b is the same as the width of the connecting hole 21a. Within the lateral projection plane of the pole post 21, the projection area of ​​the welding hole 21b coincides with the projection area of ​​the connecting hole 21a. In short, within the lateral projection plane of the pole post 21, the projection area of ​​the welding hole 21b should at least cover the projection area of ​​the connecting hole 21a.

[0067] The design of the welding hole 21b serves two purposes. First, by designing the height of the welding hole 21b and the connecting hole 21a, the penetration thickness during laser penetration welding can be kept within a suitable range, ensuring the effectiveness of the penetration welding and improving the reliability of the conductive connection between the tab 11 and the pole 21, or between the auxiliary welding piece 3 and the pole 21. Second, the weld wire after welding is located inside the welding hole 21b, ensuring that the height of the weld wire after welding does not exceed the outer surface of the pole 21, thus ensuring the flatness of the pole 21. Simultaneously, the projection area of ​​the welding hole 21b at least covers the projection area of ​​the connecting hole 21a, ensuring that the mating surfaces of the tab 11 and the pole 21, or between the auxiliary welding piece 3 and the pole 21, can be completely welded and fixed, guaranteeing the welding strength.

[0068] As mentioned above, the penetration thickness during laser penetration welding should be within a proper range, such as Figure 2 As shown in the figure, the distance between the end wall of the welding hole 21b and the end wall of the connecting hole 21a is H1, and the value range of H1 is: 0.4mm≤H1≤2mm.

[0069] It has been verified that when H1>2mm, the tab 11 and the pole piece 21, or the auxiliary welding sheet 3 and the pole piece 21 need a larger welding power when they are welded by laser penetration welding, and the laser penetration effect is not good, and when H1<0.4mm, the structural strength of the tab 11 and the pole piece 21, or the auxiliary welding sheet 3 and the pole piece 21 after welding is poor, and the pole piece 21 is prone to cracking under high pressure, therefore, the penetration thickness has the value range as above, which can not only ensure the effect of penetration welding and improve the connection reliability of the tab 11 and the pole piece 21, or the auxiliary welding sheet 3 and the pole piece 21, but also ensure the structural strength of the pole piece 21 to prevent the pole piece 21 from cracking under high pressure.

[0070] In practice, H1 can take values of 0.4mm, 1mm, 1.5mm, 2mm, etc., when H1 is 0.4mm, the welding power required for laser penetration welding is the smallest under the premise of ensuring the structural strength of the pole piece 21, and the laser penetration effect is the best; when H1 is 2mm, the structural strength of the pole piece 21 is the highest under the premise of ensuring the laser penetration effect and the connection reliability of the tab 11 and the pole piece 21, which can reduce the possibility of the pole piece 21 cracking under high pressure to the greatest extent; when H1 is 1mm or 1.5mm, a balance can be achieved between the laser penetration effect and the structural strength of the pole piece 21, and the overall quality of the battery cell can be improved.

[0071] Please continue to refer to Figures 5-6 , Figure 5 the fourth specific embodiment of the battery cell provided in the present application is a partial sectional view in the height direction; Figure 6 the fifth specific embodiment of the battery cell provided in the present application is a partial sectional view in the height direction.

[0072] In some embodiments of the present application, the auxiliary welding sheet 3 is at least zero-gap matched away from one end of the winding core 1 and the connecting hole 21a.

[0073] As above, the auxiliary welding sheet 3 is at least zero-gap matched away from one end of the winding core 1 and the connecting hole 21a, which can effectively prevent the laser from penetrating through the gap between the auxiliary welding sheet 3 and the connecting hole 21a, and avoid burning the inside of the battery cell, at this time, the connecting hole 21a and the welding hole 21b are connected, and no longer need to be welded by laser penetration welding, such as the auxiliary welding sheet 3 and the pole piece 21 can be connected by ultrasonic welding or laser welding, which has high welding convenience and higher welding reliability, and improves the conductive connection reliability of the auxiliary welding sheet 3 and the pole piece 21.

[0074] In practice, the height of the fitting section of the auxiliary welding sheet 3 for fitting with the connection hole 21a without clearance is not less than 0.4 mm. In this way, the structural strength of the pole 21 can be ensured, and the pole 21 can be prevented from cracking under high pressure.

[0075] Please continue to refer to Figure 5 In the embodiment, the auxiliary welding sheet 3 is provided with a notch part 3a facing the end wall of the winding core 1, and the tab 11 extends along the hole axis of the connection hole 21a and is at least partially located inside the notch part 3a. The notch part 3a can serve to accommodate the tab 11.

[0076] In the embodiment, the notch part 3a penetrates one of the side walls of the auxiliary welding sheet 3 in the width direction, and the tab 11 is located on one side of the auxiliary welding sheet 3. During welding, the tab 11 is located on the side close to the welding machine, and the laser or ultrasonic wave is more easily penetrated through the tab 11 to weld the tab 11 and the auxiliary welding sheet 3. In this way, the welding power is reduced, the welding strength of the tab 11 and the auxiliary welding sheet 3 is improved, and the reliability of the conductive connection between the auxiliary welding sheet 3 and the tab 11 is ensured. At the same time, the side wall penetrated by the notch part 3a only partially fits with the connection hole 21a without clearance, and the difficulty of inserting the auxiliary welding sheet 3 into the connection hole 21a is reduced, thereby improving the assembly efficiency.

[0077] In some other embodiments, the auxiliary welding sheet 3 can also be inverted right-angle U-shaped, and the auxiliary welding sheet 3 has a notch part 3a formed inside. The end of the notch part 3a facing the winding core 1 is an open end. At this time, the tab 11 penetrates into the inside of the auxiliary welding sheet 3, and the auxiliary welding sheet 3 can serve to accommodate and position the tab 11, thereby facilitating the welding and fixing of the two.

[0078] Please continue to refer to Figure 6 The auxiliary welding sheet 3 has a limiting part a facing away from the winding core 1, and the inner wall of the connection hole 21a has a limiting fitting part b facing the winding core 1. The limiting part a and the limiting fitting part b are in contact.

[0079] As can be seen, in the embodiment, the auxiliary welding sheet 3 and the connection hole 21a are relatively narrow at the end away from the winding core 1 and are relatively wide at the end close to the winding core 1. In this way, the auxiliary welding sheet 3 forms the limiting part a facing away from the winding core 1, and the inner wall of the connection hole 21a forms the limiting fitting part b facing the winding core 1. When the limiting part a and the limiting fitting part b are in contact, it indicates that the auxiliary welding sheet 3 has reached the preset installation position. It can be seen that the limiting part a and the limiting fitting part b can cooperate with each other to serve the positioning function of the auxiliary welding sheet 3. At the same time, since the end of the connection hole 21a close to the winding core 1 is relatively wide, the auxiliary welding sheet 3 can be very conveniently inserted into the inside of the connection hole 21a. The difficulty of inserting the auxiliary welding sheet 3 into the connection hole 21a is low, thereby improving the assembly efficiency.

[0080] By Figure 2 , Figure 5 and Figure 6It can be seen that, in the embodiment, the auxiliary welding sheet 3 has a spacing between the end close to the winding core 1 and the winding core 1, which can prevent the auxiliary welding sheet 3 from being inserted into the interior of the winding core 1, and avoid the problem of short circuit of the winding core 1.

[0081] Please refer to Figures 7-10 , Figure 7 for the structural schematic diagram of the winding core in the battery cell provided in the present application; Figure 8 for the top view of the cover plate assembly in the battery cell provided in the present application; Figure 9 for Figure 8 the enlarged view of a part thereof; Figure 10 for the partial bottom view of the cover plate assembly in the battery cell provided in the present application.

[0082] In the embodiment, the tab 11 is of an integral structure, i.e., the number of the tab 11 is one. It should be noted that the number of the tab 11 being one is only for the positive electrode or the negative electrode.

[0083] In practice, the number of the tab 11 can also be multiple, such as two. The two tabs 11 can be arranged in mirror symmetry, and both of the two tabs 11 are connected with the auxiliary welding sheet 3 and at least partially inserted into the interior of the connecting hole 21a to realize the conductive connection with the pole 21.

[0084] In addition, in the embodiment, the tab 11 is rectangular. In practice, the shape of the tab 11 is not limited, as long as the shape of the tab 11 is consistent with that of the connecting hole 21a, and the tab 11 can be inserted into the interior of the connecting hole 21a.

[0085] In the embodiment, the cover plate assembly 2 further comprises an aluminum sheet 22, and the pole 21 is connected to the aluminum sheet 22 by riveting process or injection molding process, and the connection is reliable.

[0086] Further, in the embodiment, the aluminum sheet 22 is further provided with a liquid injection port 22a to facilitate the addition of electrolyte when needed.

[0087] Please refer to Figures 11-12 , Figure 11 for the structural schematic diagram of the pole in some embodiments of the battery cell provided in the present application; Figure 12 for the structural schematic diagram of the pole in some other embodiments of the battery cell provided in the present application.

[0088] In the foregoing embodiments, the cross section of the pole 21 is circular. In practice, the cross section of the pole 21 can also be square or track-shaped, and the square pole or the track-shaped pole can increase the cross-sectional area of the welding hole 21b and the connecting hole 21a, increase the welding area of the tab 11 and the pole 21 or the auxiliary welding sheet 3 and the pole 21, improve the overcurrent capacity of the battery cell, and meet the fast charging design requirement.

[0089] The application also provides a battery pack comprising the aforementioned battery cell.

[0090] The battery pack of the application comprises the aforementioned battery cell, and thus has the same technical effects as the aforementioned battery cell, which will not be described herein.

[0091] The application also provides a vehicle comprising the aforementioned battery pack.

[0092] The vehicle of the application comprises the aforementioned battery pack, and thus has the same technical effects as the aforementioned battery pack, which will not be described herein.

[0093] The above is only the preferred embodiment of the application, and it should be pointed out that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the application, and these improvements and refinements should also be considered as the protection scope of the application.

Claims

1. A battery cell, characterized in that, include: The core (1) is provided with tabs (11); The cover plate assembly (2) includes a pole post (21), the pole post (21) having a connection hole (21a) on the end wall facing the core (1), at least part of the tab (11) passing through the connection hole (21a) and being electrically connected to the pole post (21).

2. The battery cell according to claim 1, characterized in that, Also includes: An auxiliary welding piece (3) is at least partially attached to and electrically connected to the side of the tab (11), and at least part of the auxiliary welding piece (3) is inserted into the connection hole (21a) and electrically connected to the pole post (21).

3. The battery cell according to claim 1, characterized in that, The tab (11) extends along the axis of the connecting hole (21a); ​​or, The tab (11) includes a straight section (a1) and a bent section (a2). The straight section (a1) extends along the direction of the hole axis of the connecting hole (21a), and the bent section (a2) extends laterally along the connecting hole (21a). The bent section (a2) is electrically connected to the pole post (21).

4. The battery cell according to claim 2, characterized in that, The tab (11) and the pole post (21) are connected by laser penetration welding, or the auxiliary welding piece (3) and the pole post (21) are connected by laser penetration welding.

5. The battery cell according to claim 2, characterized in that, The auxiliary welding piece (3) has a zero-gap fit with the connecting hole (21a) at least at one end away from the core (1).

6. The battery cell according to claim 2, characterized in that, The auxiliary welding piece (3) has a notch (3a) on the end wall facing the core (1), and the electrode (11) extends along the direction of the hole axis of the connecting hole (21a) and is at least partially located inside the notch (3a).

7. The battery cell according to claim 6, characterized in that, The notch (3a) penetrates one of the sidewalls in the width direction of the auxiliary welding piece (3).

8. The battery cell according to claim 2, characterized in that, The auxiliary welding piece (3) has a limiting part (a) facing away from the core (1), and the inner wall of the connecting hole (21a) has a limiting mating part (b) facing the core (1), and the limiting part (a) and the limiting mating part (b) abut against each other.

9. A battery pack, characterized in that, Includes the battery cell described in any one of claims 1-8.

10. A vehicle, characterized in that, Includes the battery pack as described in claim 9.

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