Battery cell and battery pack

Abstract

The utility model relates to the technical field of batteries, and discloses a battery cell and a battery pack. The battery cell comprises a shell which comprises an end plate and a side plate, the end plate and the side plate define a cavity, and two welding through holes and two mounting holes are formed in the end plate; the electrode group is arranged in the cavity, one side of the electrode group is provided with a plurality of tab groups corresponding to the two welding through holes, and each tab group comprises two tabs; the two pole columns are arranged in one-to-one correspondence with the two mounting holes; each connecting piece is provided with a pole column connecting segment and a pole lug connecting segment, the pole column connecting segment is connected with the pole column, the pole lug connecting segment is provided with a reinforcing structure, a gap is formed between the pole lug connecting segment and the corresponding welding through hole, and each pole lug penetrates through the gap and then is bent to form a bent part; and the bending parts are welded with the corresponding tab connecting segments through the corresponding welding through holes. During welding, only the tabs need to be bent, the connecting pieces do not need to be bent, the thickness of the connecting pieces and the tabs is reduced after the connecting pieces and the tabs are connected, and occupied space in the battery cell is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to an electric core and a battery pack. Background Art

[0002] Lithium-ion power batteries generally include an internal battery structure and an external battery structure. The internal battery structure mainly includes a plurality of electric cores, and the external battery structure mainly includes a battery box. The battery box provides a receiving space for the plurality of electric cores, and the battery box forms a closed space, thereby forming a complete lithium-ion battery structure.

[0003] Currently, an electric core is the smallest storage unit in a power battery. The types of electric cores can be divided into three types according to their shapes: square shell electric cores, soft-pack electric cores, and cylindrical electric cores. The square shell electric core includes a shell, a pole group, a pole column, a connecting piece, etc. The pole group is received in the shell and is formed by winding or laminating positive and negative electrode sheets and a separator. The pole tabs of the pole group are connected to the pole column through a transfer piece, and the pole tabs are located below the transfer piece. When the connecting piece and the electrode sheet are connected, they both need to be bent, which results in a relatively thick thickness after the connecting piece and the pole tab are connected, occupying more internal space of the electric core, and the utilization rate of the internal space of the electric core is relatively low. Summary of the Utility Model

[0004] In view of this, the utility model provides an electric core and a battery pack to solve the problem that when the connecting piece and the electrode sheet are connected, they both need to be bent, resulting in a relatively thick thickness after the connecting piece and the pole tab are connected and occupying more internal space of the electric core.

[0005] In a first aspect, the utility model provides an electric core, including: a shell, including an end plate and a side plate surrounding the end plate, the end plate and the side plate enclose a cavity with an opening, and two welding through holes arranged at intervals and two mounting holes arranged at intervals are formed on the end plate; a pole group, arranged in the cavity, one side of the pole group has a plurality of pole tab groups corresponding to the two welding through holes, and each pole tab group includes two pole tabs; two pole columns, arranged in one-to-one correspondence with the two mounting holes; two connecting pieces, each connecting piece has a pole column connecting segment and a pole tab connecting segment, the pole column connecting segment is connected to the corresponding pole column, a strengthening structure for strengthening the structural strength of the connecting piece is arranged on the pole tab connecting segment, a gap for the pole tab to pass through is formed between the pole tab connecting segment and the corresponding welding through hole, each pole tab passes through the gap and then is bent to form a bent portion, and the bent portion is welded to the corresponding pole tab connecting segment through the corresponding welding through hole.

[0006] Beneficial effects: When welding the connecting piece and the tab, first install the pole into the cavity of the housing and pass the tab through the corresponding gap. Then, after bending the tab, use welding processes such as laser welding or ultrasonic welding to weld the bent part to the tab connecting segment of the connecting piece. Only the tab needs to be bent, and there is no need to bend the connecting piece. Compared with the connection method in the prior art where both the connecting piece and the tab need to be bent during connection, the thickness after connection of the connecting piece and the tab becomes thinner, which can reduce the space occupied inside the battery cell, help improve the energy density of the battery cell, and enhance the space utilization rate inside the battery cell. Moreover, the bending process of the connecting piece is reduced, simplifying the manufacturing process, improving production efficiency, reducing production costs, and also reducing the potential damage or deformation risk caused by bending the connecting piece. Without bending the connecting piece, material waste can be reduced and costs can be saved. The setting of the welding through-holes avoids the bending equipment and the welding equipment, which not only facilitates bending the tab but also facilitates welding the tab and the connecting piece, improving welding efficiency and reducing costs. The two welding through-holes are spaced apart, so that the end plate is not completely disconnected in the middle, enhancing the self-strength of the end plate and further enhancing the structural strength of the housing. A strengthening structure is provided on the tab connecting segment to ensure that when the tab is welded to the connecting piece, only relying on the strength of the connecting piece itself can ensure zero-gap contact between the connecting piece and the tab, ensuring the welding effect and achieving the purpose of saving space and improving the space utilization rate in the height direction of the battery.

[0007] In an optional embodiment, the battery cell further includes two sealing members, and the two sealing members are arranged in one-to-one correspondence with the two welding through-holes, and each sealing member seals the corresponding welding through-hole.

[0008] Beneficial effects: After the connecting piece and the tab are welded, the sealing member can effectively seal the welding through-hole, prevent external moisture and pollutants from entering the battery interior, ensure the long-term performance and reliability of the battery, and also help prevent the leakage of the electrolyte inside the battery, reducing potential safety hazards.

[0009] In an optional embodiment, an explosion-proof valve is provided on the end plate, and the explosion-proof valve is located between the two welding through-holes.

[0010] Beneficial effects: The explosion-proof valve can automatically open when the internal pressure of the battery cell exceeds the safety threshold to release the internal pressure and prevent the battery cell from exploding; the explosion-proof valve is in a closed state during normal operation of the battery cell, which can effectively prevent the leakage of the electrolyte, help maintain the sealing performance of the battery cell, and extend the service life of the battery cell. Both the explosion-proof valve and the welding through-hole are provided on the end plate, and operations are carried out on the same side of the housing, which can reduce the complexity on the production line and help improve production efficiency; it is convenient for maintenance personnel to maintain and detect when problems occur in the battery cell.

[0011] In an optional embodiment, the strengthening structure is a reinforcing rib provided on the surface of the tab connecting segment and protruding towards one side.

[0012] Beneficial effects: The strength and rigidity of the connecting piece can be enhanced through the reinforcing rib. When the tab is welded to the connecting piece, the upper part of the tab needs to be pressed by a tooling, and the lower part of the connecting piece does not need tooling support, that is, the lower part of the connecting piece does not need the support of auxiliary tooling, which simplifies the welding process and improves the welding efficiency. The structure of the reinforcing rib is simple and easy to implement, reducing costs.

[0013] In an alternative embodiment, the reinforcing rib protrudes towards the end plate, or the reinforcing rib protrudes away from the end plate.

[0014] In an alternative embodiment, the reinforcing rib extends along the length direction of the end plate and divides the tab connecting segment into two connecting sub-segments, and the two connecting sub-segments are welded to the two tabs of a corresponding tab group one by one.

[0015] Beneficial effects: The reinforcing rib is arranged between the two connecting parts, enhancing the strength and stiffness of the tab connecting segment and not interfering with the area where the tab is welded on the tab connecting segment.

[0016] In an alternative embodiment, the length L of the reinforcing rib along the length direction of the end plate is greater than the length L1 of the tab along the length direction of the end plate.

[0017] Beneficial effects: The length L1 of the tab can be understood as the length of the welding area where the tab is welded to the connecting piece. Setting the length L of the reinforcing rib to be greater than the length of the welding area can further strengthen the strength and stiffness of the connecting piece, making the connecting piece not easily deformed during welding and improving the welding quality.

[0018] In an alternative embodiment, the thickness T of the connecting piece is 0.6 mm - 2.5 mm.

[0019] Beneficial effects: Setting the thickness T of the connecting piece within a reasonable range not only ensures the strength of the connecting piece itself, is not easily bent during welding, and ensures that the laser does not penetrate the connecting piece when welding the tab, but also reduces the space occupied inside the battery cell, helps improve the energy density of the battery cell, and enhances the space utilization rate inside the battery cell.

[0020] In an alternative embodiment, the height H of the reinforcing rib protruding from the surface of the tab connecting segment is 0.5 - 3 times the thickness T of the connecting piece, and / or the reinforcing rib forms a groove on the other side of the tab connecting segment, and the width W of the groove along the width direction of the end plate is 0.5 - 3 times the thickness T of the connecting piece.

[0021] Beneficial effects: Setting the height H within a reasonable range not only ensures the strength of the connecting piece itself and makes it not easy to bend during welding, but also reduces the space occupied inside the battery cell, helps improve the energy density of the battery cell, and enhances the space utilization rate inside the battery cell. Setting the width of the reinforcing rib within a reasonable range ensures the strength and manufacturability of the connecting piece itself, improves the reliability and firmness of welding, and is also easy to process.

[0022] In a second aspect, the present utility model also provides a battery pack, comprising: the above-mentioned battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific embodiments of the present utility model or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 A perspective view of a battery cell according to an embodiment of the present utility model;

[0025] Figure 2 For Figure 1 The top view of the battery cell shown;

[0026] Figure 3 For Figure 2 The sectional view taken along the A-A direction of the battery cell shown;

[0027] Figure 4 For Figure 3 The partial enlarged view of the battery cell shown;

[0028] Figure 5 For Figure 1 The perspective view of two connecting pieces of the battery cell shown;

[0029] Figure 6 For Figure 5 The top view of one connecting piece shown;

[0030] Figure 7 For Figure 6 The sectional view taken along the B-B direction of the connecting piece shown;

[0031] Figure 8 For Figure 1 The perspective view of the electrode tab passing through the connecting piece of the battery cell shown;

[0032] Figure 9 For Figure 8 The perspective view of the electrode group and the connecting piece shown;

[0033] Figure 10For Figure 8 The three-dimensional view of the pole piece bent 90° as shown;

[0034] Figure 11 For Figure 10 The three-dimensional view of the pole group and the connecting piece as shown;

[0035] Figure 12 For Figure 11 The top view of the pole group and the connecting piece as shown;

[0036] Figure 13 For Figure 12 The partial sectional view of the pole group and the connecting piece in the C-C direction as shown.

[0037] Explanation of the reference numerals:

[0038] 1. Housing; 101. End plate; 1011. Welding through hole; 1013. Explosion-proof valve; 102. Side plate;

[0039] 2. Cover plate;

[0040] 3. Terminal;

[0041] 4. Pole group; 401. Tab; 4011. Bent portion;

[0042] 5. Connecting piece; 501. Terminal connection segment; 502. Tab connection segment; 503. Reinforcing rib;

[0043] 6. Sealing plate; 601. Limiting groove;

[0044] 7. Insulating sheet; 701. Limiting protrusion;

[0045] 8. First plastic part;

[0046] 9. Second plastic part;

[0047] 10. Sealing ring. Detailed implementation manners

[0048] To make the objectives, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0049] Next, with reference to Figures 1 to 13 , the embodiments of the present utility model will be described.

[0050] According to an embodiment of the present invention, on the one hand, a battery cell is provided, comprising: a housing 1, a pole group 4, two pole posts 3 and two connecting pieces 5. The housing 1 includes an end plate 101 and a side plate 102 surrounding the end plate 101. The end plate 101 and the side plate 102 enclose a cavity with an opening. Two welding through-holes 1011 arranged at intervals and two mounting holes arranged at intervals are formed on the end plate 101; the pole group 4 is arranged in the cavity, and one side of the pole group 4 has a plurality of pole ear groups corresponding to the two welding through-holes 1011, and each pole ear group includes two pole ears 401; the two pole posts 3 are arranged in one-to-one correspondence with the two mounting holes; each connecting piece 5 has a pole post connecting segment 501 and a pole ear connecting segment 502. The pole post connecting segment 501 is connected to the corresponding pole post 3. A strengthening structure for strengthening the structural strength of the connecting piece 5 is provided on the pole ear connecting segment 502. A gap for the pole ear 401 to pass through is formed between the pole ear connecting segment 502 and the corresponding welding through-hole 1011. After each pole ear 401 passes through the gap, it is bent to form a bent portion 4011, and the bent portion 4011 is welded to the corresponding pole ear connecting segment 502 of the connecting piece 5 through the corresponding welding through-hole 1011.

[0051] When applying the battery cell of this embodiment to weld the connecting piece 5 and the pole ear 401, first, the pole group 4 is installed in the cavity of the housing 1 and the pole ear 401 is passed through the corresponding gap. Then, after the pole ear 401 is bent, the bent portion 4011 and the pole ear connecting segment 502 of the connecting piece 5 are welded together by welding processes such as laser welding or ultrasonic welding. Only the pole ear 401 needs to be bent, and there is no need to bend the connecting piece 5. Compared with the connection method in the prior art where both the connecting piece 5 and the pole ear 401 need to be bent during connection, the thickness of the connecting piece 5 and the pole ear 401 after connection becomes thinner, which can reduce the space occupied inside the battery cell, contribute to improving the energy density of the battery cell, and enhance the space utilization rate inside the battery cell; moreover, the bending process of the connecting piece 5 is reduced, the manufacturing process is simplified, the production efficiency is improved, the production cost is reduced, and the potential damage or deformation risk caused by the bending of the connecting piece 5 is also reduced. Without bending the connecting piece 5, material waste can be reduced and costs can be saved.

[0052] Furthermore, the arrangement of the welding through-holes 1011 avoids the bending device and the welding device, which not only facilitates the bending of the pole ear 401 but also facilitates the welding of the pole ear 401 and the connecting piece 5, improves the welding efficiency, and reduces the cost. The two welding through-holes 1011 are arranged at intervals, so that the end plate 101 is not completely disconnected in the middle, which improves the self-strength of the end plate 101 and further enhances the structural strength of the housing. A strengthening structure is provided on the pole ear connecting segment 502 to ensure that when the pole ear 401 is welded to the connecting piece 5, only relying on the self-strength of the connecting piece 5 can ensure zero-gap contact between the connecting piece 5 and the pole ear 401, ensuring the welding effect and achieving the purpose of saving space and improving the space utilization rate in the height direction of the battery.

[0053] In one embodiment, asFigures 1 to 4 As shown in the figure, the battery cell further includes two seals, and the two seals are arranged in one-to-one correspondence with the two welding through-holes 1011, and each seal seals the corresponding welding through-hole 1011. After the connecting piece 5 and the pole ear 401 are welded, the seals can effectively seal the welding through-holes 1011, prevent external moisture and pollutants from entering the battery interior, ensure the long-term performance and reliability of the battery, and also help prevent the leakage of the electrolyte inside the battery, reducing potential safety hazards.

[0054] Furthermore, the seals are usually made of materials with high heat resistance, good chemical stability, and excellent sealing performance. These materials need to be able to withstand the high temperature and high pressure environment during battery operation and be compatible with the material of the housing 1 to ensure long-term sealing effect. The material of the seals can be metal materials such as stainless steel, aluminum, or aluminum alloy. It can be understood that the material of the seals can also be composite materials that combine metal and plastic, etc.

[0055] Specifically, the seal is a sealing plate 6. Forming the seal with a plate is convenient for processing and manufacturing, reducing the manufacturing cost. The sealing plate 6 is welded to the end plate 101, and the welding is firm and reliable, enhancing the overall structural strength.

[0056] In one embodiment, as Figure 4 shown in the figure, the battery cell further includes two insulating sheets 7, and the two insulating sheets 7 are arranged in one-to-one correspondence with the two welding through-holes 1011, and the seals are arranged above the insulating sheets 7. The insulating sheets 7 are used to isolate the sealing plate 6 from charged components such as the pole ear 401 to prevent short circuits, and can also support internal components of the battery, such as the pole ear 401, to keep its position stable and avoid displacement during transportation or use.

[0057] Furthermore, the materials of the insulating sheets 7 are all plastics. Plastics have the advantages of electrical insulation, light weight, corrosion resistance, high structural strength, easy processing, strong plasticity, and good thermal stability.

[0058] In one embodiment, a limiting structure is provided between the insulating sheet 7 and the seal, and the limiting structure is used to limit the positions between the insulating sheet 7 and the seal. The limiting structure can ensure the relative positions between the insulating sheet 7 and the seal and limit the movement between the insulating sheet 7 and the seal, making the assembly more convenient during assembly and improving the assembly efficiency.

[0059] Further, the limiting structure includes a limiting protrusion 701 and a limiting groove 601. The limiting protrusion 701 is provided on one of the insulating sheet 7 and the seal, and the limiting groove 601 is provided on the other of the insulating sheet 7 and the seal. The cooperation of the limiting protrusion 701 and the limiting groove 601 realizes the quick positioning between the insulating sheet 7 and the seal, simplifies the assembly process, and helps improve the production efficiency.

[0060] In one embodiment, asFigure 1 and Figure 2 As shown in Figure 2 , an explosion-proof valve 1013 is provided on the end plate 101, and the explosion-proof valve 1013 is located between two welding through holes 1011. The explosion-proof valve 1013 can automatically open when the internal pressure of the battery cell exceeds the safety threshold to release the internal pressure and prevent the battery cell from exploding; the explosion-proof valve 1013 is in a closed state during the normal operation of the battery cell, which can effectively prevent the leakage of the electrolyte, help maintain the sealing performance of the battery cell, and extend the service life of the battery cell. Setting both the explosion-proof valve 1013 and the welding through holes 1011 on the end plate 101 and operating on the same side of the housing 1 can reduce the complexity of the production line and help improve production efficiency; it is convenient for maintenance personnel to maintain and detect when problems occur in the battery cell.

[0061] In one embodiment, as Figures 5 to 7 shown, the strengthening structure is a reinforcing rib 503 provided on the surface of the tab connection segment 502 and protruding toward one side. The strength and rigidity of the connecting piece 5 can be enhanced through the reinforcing rib 503. When the tab 401 is welded to the connecting piece 5, the upper part of the tab 401 needs to be pressed by a tooling, and the lower part of the connecting piece 5 does not need to be supported by tooling, that is, the lower part of the connecting piece 5 does not need the support of auxiliary tooling, which simplifies the welding process and improves the welding efficiency. The structure of the reinforcing rib 503 is simple and easy to implement, reducing costs.

[0062] It can be understood that in another embodiment, the strengthening structure is a reinforcing flange provided on the side of the tab connection segment 502, etc.

[0063] In one embodiment, the reinforcing rib 503 protrudes toward the end plate 101. Specifically, the reinforcing rib 503 is formed by stamping the middle part of the tab connection segment 502. The stamping process can make the most of the material, reduce material waste, and is also convenient for processing and manufacturing, reducing the manufacturing difficulty.

[0064] It can be understood that in another embodiment, the reinforcing rib 503 protrudes in a direction away from the end plate 101.

[0065] In one embodiment, the reinforcing rib 503 extends along the length direction of the end plate 101 and divides the tab connection segment 502 into two connection sub-segments, and the two connection sub-segments are respectively welded to the two tabs 401 of a corresponding tab group. Setting the reinforcing rib 503 between the two connection parts can enhance the strength and stiffness of the tab connection segment 502 and will not interfere with the area where the tab 401 is welded on the tab connection segment 502.

[0066] Furthermore, the reinforcing rib 503 is provided in the middle of the tab connection segment 502, and the strengthening effect is better.

[0067] It can be understood that in another embodiment, the reinforcing rib 503 can also be provided on the side of the tab connection segment 502 away from the terminal connection segment 501.

[0068] In one embodiment, as Figure 5 and Figure 12 shown, the length L of the reinforcing rib 503 along the length direction of the end plate 101 is greater than the length L1 of the tab 401 along the length direction of the end plate 101. The length L of the reinforcing rib 503 is also the Figure 12 lateral dimension of the reinforcing rib 503 in Figure 12 , and the length L1 of the tab 401 is also the Figure 12 lateral dimension of the tab 401 in Figure 12 . The length L1 of the tab 401 can be understood as the length of the welding area where the tab 401 is welded to the connecting piece 5. Setting the length L of the reinforcing rib 503 to be greater than the length of the welding area can further strengthen the strength and stiffness of the connecting piece 5, making the connecting piece 5 not easily deformed during welding and improving the welding quality.

[0069] In one embodiment, as Figures 5 to 7 shown, the thickness T of the connecting piece 5 is 0.6 mm - 2.5 mm. The thickness T of the connecting piece 5 is also the Figure 7 vertical dimension of the connecting piece 5 in Figure 7 . The thickness T of the connecting piece 5 should neither be too large nor too small. If the thickness T of the connecting piece 5 is too small, it means that the welding strength between the connecting piece 5 and the terminal 3 is weak, and thus the welding reliability between the connecting piece 5 and the terminal 3 cannot be guaranteed; if the thickness T of the connecting piece 5 is too large, it means that the connecting piece 5 is relatively thick, occupying a large amount of space inside the battery cell, and the utilization rate of the space inside the battery cell is low. Therefore, setting the thickness T of the connecting piece 5 within 0.6 mm - 2.5 mm, that is, setting the thickness T of the connecting piece 5 within a reasonable range, not only ensures the strength of the connecting piece 5 itself, is not easily bent during welding, and ensures that the laser does not penetrate the connecting piece 5 when welding the tab 401, but also can reduce the space occupied inside the battery cell, contribute to improving the energy density of the battery cell, and enhance the utilization rate of the space inside the battery cell.

[0070] In one embodiment, as Figure 7 shown, the height H of the reinforcing rib 503 protruding from the surface of the tab connection segment 502 is 0.5 - 3 times the thickness T of the connecting piece 5, that is, H is 0.5T - 3T. The height H of the reinforcing rib 503 protruding from the surface of the tab connection segment 502 is also the Figure 7The vertical dimension between the upper surface of the reinforcing rib 503 and the upper surface of the tab connection segment 502, the height H, should neither be too large nor too small. If the height H is too small, it means the strengthening effect is limited, the self-strength of the connecting piece 5 is small, and thus the welding reliability between the connecting piece 5 and the terminal post 3 cannot be ensured, and it is not easy to process. If the height H is too large, it means the height of the reinforcing rib 503 is relatively high, occupying a relatively large space inside the battery cell, and the utilization rate of the space inside the battery cell is low. Therefore, setting the height H within 0.5T - 3T, that is, setting the height H within a reasonable range, not only ensures the self-strength of the connecting piece 5 and is not easily bent during welding, but also can reduce the space occupied inside the battery cell, helping to improve the energy density of the battery cell and enhance the utilization rate of the space inside the battery cell.

[0071] In one embodiment, the reinforcing rib 503 forms a groove on the other side of the tab connection segment 502. The width W of the groove along the width direction of the end plate 101 is 0.5 - 3 times the thickness T of the connecting piece 5, that is, W is 0.5T - 3T. The width W of the groove in the width direction of the end plate 101 is also Figure 7 the lateral dimension inside the reinforcing rib 503 in the above. The width of the groove should neither be too large nor too small. If the width of the groove is too small, it means the strengthening effect is limited, the self-strength of the connecting piece 5 is small, and thus the welding reliability between the connecting piece 5 and the terminal post 3 cannot be ensured, and it is not easy to process. If the width of the groove is too large, it means the span of the reinforcing rib 503 is relatively large. With the width dimension of the connecting piece 5 unchanged, the welding area between the tab 401 and the connecting piece 5 is small, and the firmness of the welding cannot be ensured. Therefore, setting the width of the groove within 0.5T - 3T, that is, setting the width of the reinforcing rib 503 within a reasonable range, ensures the self-strength and manufacturability of the connecting piece 5, improves the reliability and firmness of welding, and is also easy to process.

[0072] In one embodiment, as Figures 10 to 13 shown, the electrode group 4 has 2 tab groups, and one welding through-hole 1011 corresponds to one tab group. In each tab group, the bending directions of the two tabs 401 are opposite, that is, the two tabs 401 are bent towards each other. When bending the tab 401, the bending head of the bending device can occupy the bending space before the tab 401 is bent, without the need to open a too large welding through-hole 1011 on the end plate 101 for avoidance, which can maximize the utilization rate in the width direction of the battery, and minimize the width of the welding through-hole 1011 of the end plate 101.

[0073] In one embodiment, as Figure 4As shown in the figure, the battery cell further includes a cover plate 2, two first plastic parts 8, a second plastic part 9 and two sealing rings 10. The cover plate 2 is arranged at the opening. The number of the pole posts 3 and the connecting pieces 5 is two. Each pole post 3 is installed at the installation hole through a first plastic part 8 and a sealing ring 10. The second plastic part 9 is arranged on the inner surface of the end plate 101. The first plastic part 8 is sleeved outside the corresponding pole post 3 and assembled at the corresponding installation hole. The first plastic part 8 can completely isolate the pole post 3 and the end plate 101, prevent short circuit between the pole post 3 and the end plate 101, and ensure electrical isolation between the pole post 3 and the end plate 101. The second plastic part 9 is located inside the end plate 101 and is used to isolate the end plate 101 from the charged components such as the pole ear 401 inside the battery to prevent short circuit; it can also support the internal components of the battery, such as the pole ear 401, keep its position stable, and avoid displacement during transportation or use. The sealing ring 10 is sleeved outside the pole post 3 and is in sealing fit with the end plate 101 and the pole post connecting segment 501, and is used to ensure the sealing performance of the battery, prevent electrolyte leakage, and at the same time prevent external moisture and impurities from entering the inside of the battery cell.

[0074] Further, the two pole posts 3 are respectively a positive pole post and a negative pole post, the two connecting pieces 5 are respectively a positive pole connecting piece and a negative pole connecting piece. The positive pole connecting piece is welded to the positive pole post, and the negative pole connecting piece is welded to the negative pole post. The materials of the positive pole post and the negative pole post are metals. Generally, the material of the negative pole post is copper, aluminum, etc., and the material of the positive pole post is aluminum, etc.

[0075] It should be noted that before welding the connecting piece 5 and the pole ear 401, the pole post 3, the first plastic part 8, the second plastic part 9 and the sealing ring 10 have been assembled on the end plate 101, and the pole post connecting segment 501 of the connecting piece 5 has been fixed on the pole post 3.

[0076] In one embodiment, the two welding through holes 1011 are located between the two installation holes.

[0077] It can be understood that in another embodiment, the two installation holes are located between the two welding through holes 1011.

[0078] In one embodiment, the welding through hole 1011 is rectangular. It can be understood that the welding through hole 1011 can also be of other shapes and is not limited thereto.

[0079] According to an embodiment of the present invention, on the other hand, a battery pack is further provided, including: the above-mentioned battery cell.

[0080] In the related art, both sides of the connecting piece are bent downward to form two downward bending parts. A pair of pole ears pass through between the two downward bending parts and are bent on the corresponding downward bending parts. When the connecting piece and the pole ear are welded, bending is required, which leads to a relatively thick thickness after the connecting piece and the pole ear are connected, occupying more internal space of the battery, and the process is also complex.

[0081] In this embodiment, the first plastic part 8, the second plastic part 9, the positive terminal, the negative terminal, the sealing ring 10, the connecting piece 5, etc. are arranged on the end plate 101. Two welding through-holes 1011 for welding the connecting piece 5 and the tab 401 are arranged on the end plate 101. The vertical tab 401 of the electrode group 4 is first assembled above the connecting piece 5, and then bent 90°. After that, welding processes such as laser welding or ultrasonic welding are used to weld the connecting piece 5 and the tab 401 through the welding through-holes 1011, reducing the bending process of the connecting piece 5, improving the space utilization rate inside the battery, and increasing the production efficiency.

[0082] Specifically, the connecting piece 5 is divided into a terminal connecting segment 501 and a tab connecting segment 502. The terminal connecting segment 501 is welded to the terminal 3. A reinforcing rib 503 protruding towards the end plate 101 or protruding away from the end plate 101 is arranged in the middle of the tab connecting segment 502, ensuring the strength of the connecting piece 5. When the tab 401 is welded to the connecting piece 5, the upper part of the tab 401 needs to be pressed by a tooling, and the lower part of the connecting piece 5 does not need to be supported by a tooling, that is, without the support of an auxiliary tooling. Only relying on the strength of the connecting piece 5 itself can ensure zero-gap contact between the connecting piece 5 and the tab 401, ensuring the welding effect and achieving the purpose of saving space and improving the space utilization rate in the height direction of the battery.

[0083] Furthermore, the welding through-hole 1011 is a stepped hole. The stepped surface of the welding through-hole 1011 is convenient for fixing the sealing plate 6. The upper surface of the tab connecting segment 502 is higher than the upper surface of the terminal connecting segment 501, that is, the connecting piece 5 has a stepped structure. Since the surface of the tab 401 on the side close to the electrode plate of the electrode group 4 is convex, the stepped structure can be adapted to the structure of the tab 401 on the side close to the electrode plate.

[0084] It should be noted that the upper surface of the bending part 4011 forms a welding area (such as Figure 10 the grid-like area shown).

[0085] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that, Comprising: A housing, including an end plate and a side plate surrounding the end plate, the end plate and the side plate enclosing a cavity with an opening, and two welding through-holes arranged at intervals and two mounting holes arranged at intervals are formed on the end plate; A pole group, arranged in the cavity, one side of the pole group having a plurality of pole ear groups corresponding to the two welding through-holes, each pole ear group including two pole ears; Two pole columns, arranged in one-to-one correspondence with the two mounting holes; Two connecting pieces, each connecting piece having a pole column connecting segment and a pole ear connecting segment, the pole column connecting segment being connected to the corresponding pole column, a strengthening structure for strengthening the structural strength of the connecting piece being provided on the pole ear connecting segment, a gap for the pole ear to pass through being formed between the pole ear connecting segment and the corresponding welding through-hole, each pole ear passing through the gap and then being bent to form a bent portion, the bent portion being welded to the corresponding pole ear connecting segment through the corresponding welding through-hole.

2. The battery cell according to claim 1, wherein The battery cell further includes two sealing members, the two sealing members being arranged in one-to-one correspondence with the two welding through-holes, each sealing member sealing the corresponding welding through-hole.

3. The battery cell according to claim 1 or 2, characterized in that, An explosion-proof valve is provided on the end plate, and the explosion-proof valve is located between the two welding through-holes.

4. The battery cell according to claim 1 or 2, characterized in that The strengthening structure is a reinforcing rib provided on the surface of the pole ear connecting segment and protruding towards one side.

5. The battery cell according to claim 4, characterized in that, The reinforcing rib protrudes towards the end plate, or, the reinforcing rib protrudes in a direction away from the end plate.

6. The battery cell according to claim 4, wherein, The reinforcing rib extends along the length direction of the end plate and divides the pole ear connecting segment into two connecting sub-segments, and the two connecting sub-segments are welded to the two pole ears of the corresponding one pole ear group in one-to-one correspondence.

7. The cell according to claim 4, wherein The length L of the reinforcing rib along the length direction of the end plate is greater than the length L1 of the pole ear along the length direction of the end plate.

8. The battery cell according to claim 4, wherein, The thickness T of the connecting piece is 0.6 mm - 2.5 mm.

9. The battery cell according to claim 8, characterized in that, The height H of the reinforcing rib protruding from the surface of the pole ear connecting segment is 0.5 - 3 times the thickness T of the connecting piece, and / or, the reinforcing rib forms a groove on the other side of the pole ear connecting segment, and the width W of the groove along the width direction of the end plate is 0.5 - 3 times the thickness T of the connecting piece.

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

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