Secondary battery and battery pack

Abstract

The utility model discloses a secondary battery and a battery pack, and belongs to the technical field of batteries. The secondary battery comprises a shell, a roll core and a collector plate, the shell is provided with a side wall extending in the first direction and a bottom wall connected with one end, in the first direction, of the side wall, and a containing cavity is defined by the side wall and the bottom wall; the roll core is arranged in the accommodating cavity; the flow collecting disc is arranged in the containing cavity and located on the side, facing the bottom wall, of the roll core, the flow collecting disc comprises a disc body and a boss which are connected, the disc body is connected with the roll core, and the boss protrudes towards the side, away from the roll core, of the disc body and is connected with the bottom wall; the orthographic projection area S1 of the boss on the plane perpendicular to the first direction and the orthographic projection area S2 of the current collecting disc on the plane perpendicular to the first direction meet the condition that S1 / S2 is larger than or equal to 1 / 4 and smaller than or equal to 1 / 3, so that it is guaranteed that the current collecting disc has enough structural strength and supporting area to support a roll core, and the overall deformation resistance of the current collecting disc is improved; meanwhile, it is guaranteed that the current collecting disc has enough effective welding area to be welded to the tab, and the overflowing capacity is guaranteed.

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to a secondary battery and battery pack. Background Technology

[0002] Cylindrical batteries are a reliable and efficient energy storage solution that provides reliable power support for a wide range of devices and applications.

[0003] However, in some cylindrical batteries, the welding power required for the current collector to tab welding area and the current collector to shell penetration welding area varies, which can easily affect the effective welding area of ​​the current collector to the tab and cause insufficient current carrying capacity. Utility Model Content

[0004] The purpose of this utility model is to provide a secondary battery that overcomes the technical problem that the effective welding area between the current collector and the electrode is reduced due to the welding power between the current collector and the shell, resulting in insufficient current carrying capacity. Another purpose of this application is to provide...

[0005] Technical solution: This application discloses a secondary battery, comprising:

[0006] The housing has a sidewall extending in a first direction and a bottom wall connecting one end of the sidewall in the first direction, the sidewall and the bottom wall forming a receiving cavity;

[0007] The core is disposed within the receiving cavity;

[0008] A collector plate is disposed in the receiving cavity and located on the side of the winding core facing the bottom wall. The collector plate includes a plate body and a boss connecting the plate body. The plate body is connected to the winding core. The boss protrudes from the side of the plate body away from the winding core and is connected to the bottom wall.

[0009] The orthographic projection area of ​​the boss on a plane perpendicular to the first direction is S1 mm. 2 The orthographic projection area of ​​the collector disk on a plane perpendicular to the first direction is S² mm. 2 ,satisfy:

[0010] 1 / 4≤S1 / S2≤1 / 3.

[0011] In some embodiments, the bottom wall has a first through hole, the boss includes a first protrusion, the first protrusion has a top surface that fits the bottom wall, and the first protrusion has a second through hole, the second through hole is opened on the top surface and is correspondingly disposed to the first through hole.

[0012] In some embodiments, a first cavity is formed between the first protrusion and the core 20, and the protrusion further includes a second protrusion connected to the bottom wall, and a second cavity is formed between the second protrusion and the core, the second cavity communicating with the second through hole via the first cavity.

[0013] In some embodiments, the first protrusion has a first radial dimension D1 mm in its orthographic projection onto a plane perpendicular to the first direction, the second through hole has a second radial dimension D2 mm in its orthographic projection onto a plane perpendicular to the first direction, and the collector has a third radial dimension D3 mm in its orthographic projection onto a plane perpendicular to the first direction, satisfying D2 < D1 ≤ 0.5D3.

[0014] In some embodiments, the collector includes a plurality of disk bodies and a plurality of second protrusions, the plurality of disk bodies surrounding a first protrusion and the plurality of second protrusions surrounding the first protrusion, each disk body and each second protrusion being connected to the first protrusion, and in the circumferential direction surrounding a first direction, the plurality of disk bodies and the plurality of second protrusions are alternately connected.

[0015] In some embodiments, the orthographic projection of the second protrusion onto a plane perpendicular to the first direction is a fan shape;

[0016] And / or, the orthographic projection of the disk body onto a plane perpendicular to the first direction is a sector.

[0017] In some embodiments, along the first direction, the boss has a thickness dimension d1 mm, and the disk body has a thickness dimension d2 mm, satisfying d1 > d2.

[0018] In some embodiments, the collector plate includes a plurality of second protrusions, each second protrusion having a third through hole, and the third through hole of each second protrusion being equidistant from the second through hole.

[0019] In some embodiments, the sidewall has a chamfered portion, which is connected to the outer edge of the bottom wall;

[0020] Along the first direction, the chamfered portion has a height dimension b mm, and the distance between the collector plate and the bottom wall has a maximum dimension a mm, satisfying: a≥b.

[0021] This application also discloses a battery pack, including the secondary battery as described in the above embodiments.

[0022] Beneficial Effects: The secondary battery of this application embodiment includes a casing, a winding core, and a current collector; the casing has a first direction and a receiving cavity; the winding core is disposed within the receiving cavity; the current collector is disposed within the receiving cavity and located on one side of the winding core in the first direction, the current collector includes a disk body and a boss connected together, the disk body is connected to the winding core, and the boss protrudes towards the side of the disk body away from the winding core and is connected to the casing; the orthographic projection area of ​​the boss on a plane perpendicular to the first direction is S1mm. 2 The orthographic projection area of ​​the collector disk on a plane perpendicular to the first direction is S² mm. 2 The following condition must be met: 1 / 4 ≤ S1 / S2 ≤ 1 / 3. In the secondary battery of this application, by setting the orthogonal projection area S1 of the boss on the plane perpendicular to the first direction and the orthogonal projection area S2 of the current collector on the plane perpendicular to the first direction to satisfy: 1 / 4 ≤ S1 / S2 ≤ 1 / 3, it is ensured that the current collector has sufficient structural strength and support area to support the core, thereby improving the overall deformation resistance of the current collector. At the same time, it is ensured that the current collector has sufficient effective welding area to weld with the electrode tab, ensuring the current carrying capacity and improving the quality and service life of the secondary battery.

[0023] The battery pack of this application embodiment includes the above-mentioned secondary battery, and therefore can have all the technical features and beneficial effects of the above-mentioned secondary battery, which will not be repeated here. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a three-dimensional structural diagram of the secondary battery of this application;

[0026] Figure 2 for Figure 1 Cross-sectional view along the AA direction;

[0027] Figure 3 for Figure 2 A magnified view of a portion of point B in the middle;

[0028] Figure 4 for Figure 3 A magnified view of a portion of point C in the middle;

[0029] Figure 5 This is a three-dimensional structural diagram of the current collector in the secondary battery of this application;

[0030] Figure 6This is a top view of the current collector in the secondary battery of this application.

[0031] Figure 7 for Figure 6 Cross-sectional view along the EE direction;

[0032] Figure 8 for Figure 3 A magnified view of a portion of point D in the middle;

[0033] Reference numerals: 10, shell; X, first direction; 100, receiving cavity; 20, core; 30, collector plate; 31, plate body; 32, boss; 101, bottom wall; 1010, first through hole; 321, first protrusion; 3211, top surface; 3210, second through hole; 322, second protrusion; 310, first groove; 301, first cavity; 302, second cavity; Y, second direction; 3220, third through hole; 102, side wall; 1021, chamfer. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0035] In the description of this application, it should be understood that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. In the description of this application, "multiple" means two or more, and "at least one" can refer to one, two, or more, unless otherwise explicitly specified. The terms "first," "second," and "third," etc., are only for the convenience of description and are used to name parts or embodiments by number, and do not imply any order of importance between the parts or embodiments.

[0036] It should also be noted that in the accompanying drawings of this application, an arrow marked X indicates the first direction, and an arrow marked Y indicates the second direction. The introduction of the first and second directions in this application's description is to more clearly define the structure and relative positional relationships of the components in the secondary battery. In actual implementation, the first direction is generally the vertical direction, and the second direction is generally the horizontal direction; the first and second directions intersect. Optionally, the first and second directions are perpendicular to each other to optimize the layout of the secondary battery. In the description of this application, "perpendicular" means completely perpendicular to 90° or almost completely perpendicular; for example, an angle between 80° and 100° is considered perpendicular.

[0037] As a preamble to the embodiments of this application, in some cylindrical batteries, the welding power required for the current collector and the tab welding area and the current collector and the shell through welding area are different, which can easily affect the effective welding area of ​​the current collector and the tab, resulting in insufficient current carrying capacity; and the current collector is a flat plate structure, which can easily cause interference between the internal core and the inner R-angle of the bottom of the shell during the assembly process, increasing the probability of lithium plating and affecting the quality and service life of the battery.

[0038] In view of this, embodiments of this application provide a secondary battery, which aims to solve at least one of the above-mentioned technical problems.

[0039] Please see Figures 1 to 8 As shown, the secondary battery of this application includes: a housing 10, a core 20, and a current collector 30. The housing 10 has a first direction X and a receiving cavity 100. The housing 10 provides external protection and isolation for the secondary battery, and also serves to dissipate heat, prevent leakage, and provide mechanical support. It is an important component ensuring the performance and safety of the secondary battery. The core 20 is disposed within the receiving cavity 100. The core 20 is the core component of the secondary battery and is generally formed by stacking and winding a positive electrode sheet, a first separator layer, a negative electrode sheet, and a second separator layer together, or by sequentially stacking multiple positive electrode sheets, a first separator layer, a negative electrode sheet, and a second separator layer. The current collector 30 is disposed within the receiving cavity 100 and located on one side of the core 20 in the first direction X. The core 20 has tabs, and the current collector 30 is electrically connected to the tabs of the core to collect the current from the core 20 and further conduct the current to the housing 10 or the terminal post. In some designs, the housing 10 is electrically connected to one pole of the core 20, and the terminal post is electrically connected to the other pole of the core 20. This application embodiment takes the current collector 30, which conducts current between the housing 10 and the core 20 in this type of battery, as an example to illustrate how to achieve the conduction of the internal circuit of the secondary battery.

[0040] Specifically, the housing 10 has a sidewall 102 extending along a first direction X, and a bottom wall 101 connecting one end of the sidewall 102 in the first direction X. The sidewall 102 and the bottom wall 101 form a receiving cavity 100. A collector plate 30 is disposed within the receiving cavity 100 and is located on the side of the winding core 20 facing the bottom wall 101. The collector plate 30 includes a connected disc body 31 and a boss 32, such as... Figure 3 and Figure 4 As shown, the disc body 31 is connected to the core 20, and the boss 32 protrudes from the side of the disc body 31 away from the core 20 and is connected to the bottom wall 101; the orthographic projection area of ​​the boss 32 on the plane perpendicular to the first direction X is S1 mm. 2 The orthographic projection area of ​​the collector disk 30 on a plane perpendicular to the first direction X is S² mm. 2 The following conditions must be met: 1 / 4 ≤ S1 / S2 ≤ 1 / 3. It is important to understand that in the secondary battery, by providing a protrusion 32 on the disc body 31, with the protrusion 32 protruding towards the side of the disc body 31 away from the core 20, and welding the protrusion 32 to the bottom wall 101 of the casing 10, and welding the disc body 31 to the electrode tabs, the protrusion 32 ensures that the welding positions of the current collector 30 and the electrode tabs, and the current collector 30 and the casing 10, are at different heights. This effectively reduces the heat transferred to the disc body 31 and the core 20, thereby reducing the risk of the core 20 and the electrode tabs being burned. This accommodates the different welding power requirements of different welding objects, and avoids limiting the welding area between the current collector 30 and the electrode tabs due to different welding power at different parts of the current collector 30, ensuring that the current collector 30 and the electrode tabs have sufficient effective welding area.

[0041] The orthographic projection area of ​​the boss 32 on the plane perpendicular to the first direction X is S1, and the orthographic projection area of ​​the current collector 30 on the plane perpendicular to the first direction X is S2. For the current collector 30 that satisfies 1 / 4≤S1 / S2≤1 / 3, the welding area between it and the electrode tab is more appropriately distributed with the welding area between the current collector 30 and the shell 10. This ensures that the current collector 30 has sufficient structural strength and support area to support the core 20, improves the overall deformation resistance of the current collector 30, and ensures that the current collector 30 has sufficient effective welding area to weld with the electrode tab, ensuring the current carrying capacity and significantly improving the quality and service life of the secondary battery.

[0042] Specifically, S1 / S2 can be any value from 1 / 4, 13 / 48, 7 / 24, 15 / 48, 1 / 3, or a range between any two values. Within the range of 1 / 4 to 1 / 3, the larger S2 / S1 is, the larger the area of ​​the boss 32, the greater the structural strength of the current collector 30 and the area supporting the core 20, and the smaller the welding area between the current collector 30 and the electrode tab; conversely, the smaller S2 / S1 is, the smaller the area of ​​the boss 32 and the larger the welding area between the current collector 30 and the electrode tab. Within the above range, the supporting strength and current carrying capacity of the current collector 30 can be guaranteed, and the corresponding secondary battery can have good stability and charge / discharge efficiency. Optionally, the boss 32 and the disk body 31 of this application are integrally formed, and the side of the boss 32 facing the core 20 has a groove to reduce the weight of the current collector 30, thereby ensuring the overall lightweight of the secondary battery. Optionally, the boss 32 and the disc 31 of this application can be thin sheet structures and integrally die-cast.

[0043] Please see Figures 1 to 4 As shown, in some embodiments, the housing 10 has a bottom wall 101 on one side in the first direction X. The bottom wall 101 has a first through hole 1010, which communicates with the receiving cavity 100. The boss 32 includes a first protrusion 321, which has a top surface 3211 that fits against the bottom wall 101. The first protrusion 321 also has a second through hole 3210, which is formed on the top surface 3211 and is correspondingly arranged with the first through hole 1010. It should be understood that by attaching the top surface 3211 of the first protrusion 321 to the bottom wall 101 and welding it to the bottom wall 101 of the housing 10, a reliable connection is formed between the collector 30 and the housing 10. At the same time, the first protrusion 321 has a second through hole 3210 corresponding to the first through hole 1010. That is, the first through hole 1010 and the second through hole 3210 are arranged along the first direction X and are connected to each other, so that the bottom of the housing 10 has a liquid injection function. After the secondary battery is assembled, electrolyte can be injected into the housing through the bottom of the housing 10.

[0044] Please see Figure 3 and Figure 4As shown, in some embodiments, a first cavity 301 is formed between the first protrusion 321 and the core 20. The protrusion 32 also includes a second protrusion 322, which connects to the bottom wall 101 and forms a second cavity 302 between the second protrusion 322 and the core 20. The second cavity 302 is connected to the second through hole 3210 via the first cavity 301. The first cavity 301 formed by the first protrusion 321 and the core 20, and the second cavity 302 formed by the second protrusion 322 and the core 20, reduce the internal space occupied by the battery pack and reduce the weight of the current collector 30, thereby ultimately reducing the overall weight of the battery pack. On the other hand, the second cavity 302 connects the first cavity 301 and the second through hole 3210, providing a gas emission path and improving the safety and stability of the battery pack.

[0045] Please see Figure 5 and Figure 6 As shown, in some embodiments, the boss 32 further includes a plurality of second protrusions 322, which are spaced apart from each other and surround the first protrusion 321, and are respectively connected to the bottom wall 101. By having a plurality of second protrusions 322 surround the first protrusion 321, the contact area between the boss 32 and the bottom wall 101 is increased, the structural strength of the boss 32 is improved, and the current collector 30 is ensured to provide sufficient and effective support for the core 20, avoiding local pressure damage to the battery cell; moreover, for the wound core 20, the space between the second protrusions 322 and the core 20 can allow electrolyte flow, improving the efficiency of electrolyte flow and wetting between the layers of the core 20, increasing the pressure threshold of the injection process, and accelerating the injection speed.

[0046] Please see Figure 5As shown, in some embodiments, the orthographic projection of the first protrusion 321 onto a plane perpendicular to the first direction X has a first radial dimension D1 mm, the orthographic projection of the second through hole 3210 onto a plane perpendicular to the first direction X has a second radial dimension D2 mm, and the orthographic projection of the collector disk 30 onto a plane perpendicular to the first direction X has a third radial dimension D3 mm, satisfying D2 < D1 ≤ 0.5D3. It should be understood that the first radial dimension D1 of the first protrusion 321, the second radial dimension D2 of the second through hole 3210, and the third radial dimension D3 of the collector disk 30, for example, in the case where the collector disk 30 is a circular collector disk, respectively represent the diameter length of the orthographic projection of the first protrusion 321, the second through hole 3210, and the collector disk 30 onto a plane perpendicular to the first direction X. By setting the first radial dimension D1 of the first protrusion 321, the second radial dimension D2 of the second through hole 3210, and the third radial dimension D3 of the collector plate 30 to meet the above conditions, the first radial dimension D1 is avoided from being too large, ensuring that the plate body 31 has sufficient effective area for welding the tabs, satisfying the current carrying capacity of the tab welding area, and at the same time ensuring a more reliable connection between the first protrusion 321 and the bottom wall 101 of the housing 10. With the area S1 of the control boss 32 remaining constant, when D1 meets the above range, the larger D1 is, the larger the area of ​​the first protrusion 321, and the relatively smaller the area of ​​the second protrusion 322. This results in a relatively larger welding area between the plate body 31 of the collector plate 30 and the tabs, a slight decrease in the overall support strength of the collector plate 30, but an improvement in the current carrying capacity. Conversely, the smaller D1 is, the smaller the area of ​​the first protrusion 321 and the relatively larger the area of ​​the second protrusion 322. As a result, the welding area between the disc body 31 of the current collector 30 and the electrode tab becomes relatively smaller, the overall support strength of the current collector 30 is improved, but the current carrying capacity is reduced.

[0047] Next, several embodiments and comparative examples are provided to illustrate the effect of the secondary battery of this application. S1 and S2 can be obtained by selecting some common area measurement methods. For example, for the protrusion 32, the measurement method for area S1 can be selected according to its shape. When the protrusion 32 is strip-shaped, fan-shaped, or ring-shaped, the corresponding dimensions of the protrusion 32 can be measured using measuring tools such as vernier calipers or micrometers, and the area S1 can be calculated using geometric formulas. Alternatively, it can be measured using image processing methods. For example, an image of the protrusion 32 in the secondary battery can be acquired, the image can be loaded using image processing software, and S1 can be measured using the software. Alternatively, it can be measured using projection methods. The image area of ​​the protrusion 32 can be measured using projection measurement equipment such as a digital microscope or image measuring instrument to obtain the area S1. Correspondingly, the area S2 can be obtained directly through projection measurement or through image processing using image software. Similarly, the corresponding dimensions of the first protrusion 321, the second through hole 3210, and the collector plate 30 can be measured using measuring tools such as vernier calipers or micrometers.

[0048] The impact of S2 / S1 on the effective welding area between the current collector 30 and the electrode can be determined by the current carrying capacity, and the impact of D1 on the effective welding area between the current collector 30 and the electrode can also be determined by the current carrying capacity. The criteria for determining the current carrying capacity are as follows: under the 15-minute and 30-minute fast charging strategies, the typical charging current range is 120A to 160A, and the maximum temperature on the current collector 30 during the process is ≤60℃, which is considered qualified; if the maximum temperature on the current collector 30 reaches ≥60℃ during the 15-minute or 30-minute fast charging, it is considered unqualified. The influence of S2 / S1 on the support strength of the manifold 30 can be determined by the maximum deformation. The influence of D1 on the support strength of the manifold 30 can also be determined by the maximum deformation. The criterion for the maximum deformation is: if the manifold 30 is continuously pressurized under a pressure of 5N for 10 minutes, and the deformation size in the first direction X is ≤0.3mm, it is considered qualified; if the deformation size in the first direction X of the manifold 30 is >0.3mm, it is considered unqualified.

[0049] The experimental results of the examples and comparative examples are shown in the table below:

[0050]

[0051]

[0052] As shown in the table above, in Examples 1 to 6, when S2 / S1 is controlled within the range of 1 / 4 to 1 / 3, the temperature of the current collector 30 remains below 60°C during 15-minute and 30-minute fast charging. This indicates that the overcurrent capacity of the secondary battery is guaranteed, and the secondary battery exhibits good charge and discharge efficiency. Furthermore, when the current collector 30 is continuously pressurized at 5N for 10 minutes, the deformation dimension in the first direction X is less than 0.3mm, demonstrating that the current collector 30 has high support strength. In Comparative Examples 1 and 3, when S2 / S1 is less than 1 / 4, the temperature of the current collector 30 remains below 60°C during 15-minute and 30-minute fast charging. While the overcurrent capacity of the secondary battery is guaranteed, the deformation dimension of the current collector 30 in the first direction X exceeds 0.3mm, indicating a decrease in support strength, which does not meet the requirements. As shown in Comparative Example 2, when S2 / S1 is greater than 1 / 3, the temperature of the current collector 30 exceeds 60℃ under 15-minute and 30-minute fast charging, and the current carrying capacity decreases, which does not meet the requirements.

[0053] As in Examples 4 to 7, when D1 is controlled to be less than or equal to 0.5D3, and the collector plate 30 is continuously pressurized under a pressure of 5N for 10 minutes, the deformation size in the first direction X is much less than 0.3mm, indicating that the collector plate 30 has high support strength. In Example 8, when D1 is greater than 0.5D3, and the collector plate 30 is continuously pressurized under a pressure of 5N for 10 minutes, the deformation size in the first direction X increases to 0.23, indicating that the support strength of the collector plate 30 decreases.

[0054] Please see Figures 4 to 6 As shown, in some embodiments, the current collector 30 includes multiple disks 31 and multiple second protrusions 322. The multiple disks 31 surround the first protrusion 321, and the multiple second protrusions 322 surround the first protrusion 321. Each disk 31 and each second protrusion 322 is connected to the first protrusion 321. Furthermore, in the circumferential direction surrounding the first direction X, the multiple disks 31 and the multiple second protrusions 322 are alternately connected. By arranging multiple disks 31 surrounding the first protrusion 321 and alternately arranged with the second protrusions 322, on the one hand, the overall support strength of the current collector 30 can be guaranteed, while the welding area between the current collector 30 and the electrode can be improved, ensuring the current carrying capacity of the welding area between the electrode and the current collector 30. On the other hand, the arrangement of multiple disks 31 makes the current collector 30 have better overall deformation resistance. Two adjacent second protrusions 322 and the first protrusion 321 jointly support a single disk 31, and the overall deformation risk of the current collector 30 is controllable. It should be understood that the first protrusion 321, the second protrusion 322 and the disc body 31 can be formed by stamping and are an integral structure. Each disc body 31 is provided with a first groove 310 at the position adjacent to the second protrusion 322. The first groove 310 is formed by stamping and blanking and has an exhaust function.

[0055] Furthermore, the disc body 31, together with the second protrusion 322 and the first protrusion 321, forms a fluid channel. A through groove is provided on the disc body 31, and the fluid channel and the through groove are connected to further ensure the smooth flow of fluid in the secondary battery. For the wound core 20 formed by winding, the space between the multiple second protrusions 322 and the wound core 20 can be used for electrolyte flow, which further improves the efficiency of electrolyte flow and wetting between the layers of the wound core 20, increases the pressure threshold of the liquid injection process, and speeds up the liquid injection speed.

[0056] Please see Figure 5 and Figure 6 As shown, in some embodiments, the orthographic projection of the second protrusion 322 onto a plane perpendicular to the first direction X is fan-shaped; and / or, the orthographic projection of the disk 31 onto a plane perpendicular to the first direction X is fan-shaped. It should be understood that the fan-shaped structure of the second protrusion 32 can increase the welding area with the housing 10, ensuring a stable and reliable connection between the current collector 30 and the housing 10; while the fan-shaped structure of the disk 31 makes the outer end of the disk 31 have a larger weldable area, making it easier to weld the tabs to the disk 31, and improving welding reliability. The larger weldable area between the disk 31 and the tabs better guarantees the current-carrying capacity of the welding area between the tabs and the current collector 30.

[0057] Please see Figure 7 As shown, in some embodiments, the boss 32 along the first direction X has a thickness dimension d1 mm, and the disk 31 has a thickness dimension d2 mm, satisfying d1 > d2. It should be understood that the relationship between d1 and d2 is satisfied to allow the disk 31 and boss 32 to adapt to different welding power. To ensure stable current flow, compared to the welding power required for welding the disk 31 to the tab, the penetration welding of the boss 32 to the bottom wall 101 of the housing 10 requires a higher welding penetration capability. Welding the tab area with the power required for the penetration welding region of the boss 32 to the bottom wall 101 of the housing 10 can easily cause diaphragm burn. When the welding power used for welding the disk 31 to the tab is applied to welding the boss 32 to the bottom wall 101 of the housing 10, the weld depth and width may not meet the current flow requirements. Furthermore, d1 can be 0.5 mm, and d2 can be 0.3 mm.

[0058] In some embodiments, the manifold 30 includes a plurality of second protrusions 322, each second protrusion 322 having a third through hole 3220, and the distance between the third through hole 3220 and the second through hole 3210 of each second protrusion 322 is equal. It should be understood that by opening the third through hole 3220 on the second protrusion, the uniformity of fluid injection can be improved. Further, the first through hole 1010 is opened near the center of the bottom wall 101, and the third through hole 3220 is opened near the center of the second protrusion, that is, the circle formed by the centers of the central holes on the second protrusion is concentric with the first through hole 1010, or the arc of the plurality of third through holes 3220 around the second through hole 3210 is equal, that is, the plurality of third through holes 3220 are arranged at equal intervals and together surround the second through hole 3210. By using concentric circles, the distance between the third through hole 3220 and the first through hole 1010 of each second protrusion is equal, thereby improving the uniformity of fluid injection. Furthermore, during the assembly of the secondary battery, the third through hole 3220 can also be used for the positioning and installation of the current collector plate 30. For example, when welding the current collector plate 30 to the core 20, the third through hole 3220 can be used to position the current collector plate 30, or it can be used for visual recognition of the relative position and orientation of the current collector plate 30 to achieve automated welding.

[0059] Please see Figure 8 As shown, in some embodiments, the housing 10 has a bottom wall 101 and a side wall 102. The side wall 102 surrounds the bottom wall 101 and is located on one side of the bottom wall 101 in the first direction X. The side wall 102 has a chamfered portion 1021, which is connected to the outer edge of the bottom wall 101. Along the first direction X, the chamfered portion 1021 has a sixth dimension b mm, and the collector 30 has a maximum dimension a mm away from the bottom wall 101, satisfying: a ≥ b. It is important to understand that the current collector 30 has a boss structure to support the core 20 at a certain height. By ensuring that the sixth dimension b of the chamfered portion 1021 and the maximum dimension a of the current collector 30 from the bottom wall 101 satisfy the above relationship, a safe distance is maintained between the core 20 and the chamfered portion 1021. This ensures that the core 20 and the chamfered portion 1021 do not come into direct contact, preventing the electrode in the core 20 from being squeezed and broken by the chamfered portion 1021, or even powder shedding, which could cause short circuits and other safety risks. Furthermore, it prevents lithium plating from occurring in the core 20 during long-term cycling.

[0060] This application also discloses a battery pack, including the secondary battery as described in the above embodiments.

[0061] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0062] The above provides a detailed description of a secondary battery and battery pack provided in the embodiments of this application, and uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A secondary battery, characterized in that, include: The housing (10) has a first direction (X), a sidewall (102) extending along the first direction (X), and a bottom wall (101) connecting one end of the sidewall (102) in the first direction (X), the sidewall (102) and the bottom wall (101) forming a receiving cavity (100). The core (20) is disposed within the receiving cavity (100); A collector plate (30) is disposed in the receiving cavity (100) and located on the side of the core (20) facing the bottom wall (101). The collector plate (30) includes a plate body (31) and a boss (32) connecting the plate body (31). The plate body (31) is connected to the core (20). The boss (32) protrudes from the side of the plate body (31) away from the core (20) and is connected to the bottom wall (101). The orthographic projection area of ​​the boss (32) on a plane perpendicular to the first direction (X) is S1mm. 2 The orthographic projection area of ​​the collector disk (30) on a plane perpendicular to the first direction (X) is S2 mm. 2 ,satisfy: 1 / 4≤S1 / S2≤1 / 3.

2. The secondary battery according to claim 1, characterized in that, The bottom wall (101) has a first through hole (1010), and the boss (32) includes a first protrusion (321). The first protrusion (321) has a top surface (3211) that fits against the bottom wall (101), and the first protrusion (321) has a second through hole (3210). The second through hole (3210) is opened on the top surface (3211) and is correspondingly arranged with the first through hole (1010).

3. The secondary battery according to claim 2, characterized in that, A first cavity (301) is formed between the first protrusion (321) and the core (20). The boss (32) also includes a second protrusion (322), which is connected to the bottom wall (101). A second cavity (302) is formed between the second protrusion (322) and the core (20). The second cavity (302) is connected to the second through hole (3210) through the first cavity (301).

4. The secondary battery according to claim 2, characterized in that, The first protrusion (321) has a first radial dimension D1 mm in its orthographic projection onto a plane perpendicular to the first direction (X), the second through hole (3210) has a second radial dimension D2 mm in its orthographic projection onto a plane perpendicular to the first direction (X), and the collector plate (30) has a third radial dimension D3 mm in its orthographic projection onto a plane perpendicular to the first direction (X), satisfying D2<D1≤0.5D3.

5. The secondary battery according to claim 3, characterized in that, The collector disk (30) includes a plurality of disk bodies (31) and a plurality of second protrusions (322). The plurality of disk bodies (31) surround the first protrusion (321), and the plurality of second protrusions (322) surround the first protrusion (321). Each disk body (31) and each second protrusion (322) is connected to the first protrusion (321). Furthermore, in the circumferential direction surrounding the first direction (X), the plurality of disk bodies (31) and the plurality of second protrusions (322) are alternately connected.

6. The secondary battery according to claim 5, characterized in that, The orthographic projection of the second protrusion (322) onto a plane perpendicular to the first direction (X) is a fan shape; And / or, the orthographic projection of the disk (31) onto a plane perpendicular to the first direction (X) is a sector.

7. The secondary battery according to claim 1, characterized in that, Along the first direction (X), the boss (32) has a thickness dimension d1 mm, and the disk (31) has a thickness dimension d2 mm, satisfying d1 > d2.

8. The secondary battery according to claim 5, characterized in that, The collector plate (30) includes a plurality of second protrusions (322), each of the second protrusions (322) having a third through hole (3220), and the third through hole (3220) of each of the second protrusions (322) being equidistant from the second through hole (3210).

9. The secondary battery according to claim 1, characterized in that, The sidewall (102) has a chamfered portion (1021), which is connected to the outer edge of the bottom wall (101); Along the first direction (X), the chamfered portion (1021) has a height dimension b mm, and the collector plate (30) has a maximum distance a mm from the bottom wall (101), satisfying: a≥b.

10. A battery pack, characterized in that, Includes a secondary battery as described in any one of claims 1 to 9 above.

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