A cylindrical battery and battery pack

Abstract

This utility model provides a cylindrical battery and battery pack, comprising: a casing, terminals, an electrode assembly, and a current collector. The casing includes an end wall with terminal holes; the terminals are installed in the terminal holes and insulated from the end wall; the current collector is disposed within the casing and located between the electrode assembly and the terminals; the current collector has a first solder mark and a second solder mark, the first solder mark being formed by welding the current collector to the terminals and distributed circumferentially, the second solder mark being formed by welding the current collector to the current collecting section, a first gap between the second solder mark and the first solder mark having a minimum radial dimension of A, and a second gap between the second solder mark and the outer periphery of the current collector having a radial dimension of B, where 0≤B / A≤1. This cylindrical battery can improve the technical problems of unreasonable distribution of the first and second solder marks and low safety in existing cylindrical batteries.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a cylindrical battery and battery pack. Background Technology

[0002] Currently, in the manufacturing process of cylindrical batteries, especially lithium batteries, the welding process between the terminals, current collector, and current collector section is a crucial step in constructing the conductive path of the cylindrical battery. To facilitate the welding between the terminals, current collector, and current collector section, the current collector has a first weld mark and a second weld mark. The first weld mark is located on the inner ring of the current collector, and the second weld mark is located on the outer ring of the first weld mark. The first weld mark is formed by welding the terminals to the current collector and is also called the terminal weld mark. The second weld mark is formed by welding the current collector to the current collector section and is also called the current collector section weld mark.

[0003] The first and second solder marks each undertake a portion of the electrical connection and current-carrying tasks, and both occupy a certain area of ​​the current collector. Within the limited area of ​​the current collector, the first and second solder marks need to be rationally distributed to achieve the best current-carrying effect. Furthermore, the first and second solder marks need to maintain a certain distance in the radial direction of the current collector. If the distance is too narrow, it will affect processing, and there is a risk of melt-through and damage to the current collector during welding. A narrow distance will also lead to overlapping solder joints, forming a high-resistance area. If the distance is too large, the length of the second solder mark on the current collector and the current collector section will be significantly insufficient, resulting in an increase in DC internal resistance (DCR) and affecting the safety of the cylindrical battery. Utility Model Content

[0004] In view of the shortcomings of the prior art, the present invention provides a cylindrical battery and battery pack to improve the technical problems of unreasonable distribution of the first and second solder marks and low safety of the existing cylindrical batteries.

[0005] This utility model provides a cylindrical battery, comprising: a casing, terminals, an electrode assembly, and a current collector. The casing forms a receiving space and includes an end wall with a terminal hole. The terminal is installed in the terminal hole and insulated from the end wall. The electrode assembly is housed within the receiving space and includes a positive electrode, a negative electrode, and a separator separating the positive and negative electrodes. The positive electrode, negative electrode, and separator are stacked and wound to form a core. The core has a central hole and a current collector located at the end of the electrode assembly facing the terminal. The current collector is disposed within the casing and located between the electrode assembly and the terminal.

[0006] The current collector has a first weld mark and a second weld mark. The first weld mark is formed by welding the current collector to the pole post and is distributed circumferentially. The second weld mark is formed by welding the current collector to the current collection part. There is a first gap between the second weld mark and the first weld mark. The minimum radial dimension of the first gap is A. There is a second gap between the second weld mark and the outer periphery of the current collector and the radial dimension of the second gap is B. 0≤B / A≤1.

[0007] In one embodiment of the present invention, the first solder mark is formed by welding the current collector plate, the current collector part, and the electrode post; the first solder mark is formed by welding the electrode post, the current collector plate, and the current collector part together at the welding position from the side of the electrode post away from the current collector plate.

[0008] In one embodiment of this utility model, the first solder mark is a continuously distributed arc shape, and the second solder mark is continuously distributed along the circumference or spaced along the radial direction; the positive electrode and the negative electrode include a current collector, the current collector includes a coated area coated with active material and an uncoated area uncoated with active material, the uncoated area extends out of the separator along the axial direction of the cylindrical battery to form an electrode tab, the electrode tab is bent and stacked towards the central axis of the cylindrical battery to form a stacked part, and the current collector is a stacked part;

[0009] Define the radius of the center hole as R. hole The radius of the first solder mark is R. in At the welding position where the first solder mark is formed, the thickness of the tab of the stacked part is T; the thickness of the current collector along the axial direction of the cylindrical battery is h1, and the thickness of the terminal along the axial direction of the cylindrical battery is h2, R hole and R in satisfy:

[0010] R in =R hole +h1+h2+M×T, where T, h1, h2, and R are... in and R hole The units are all mm, and M is the number of layers of the electrode lugs involved in the welding, which is a natural number and 3≤M≤10.

[0011] In one embodiment of the present invention, the maximum radial dimension B of the second interval satisfies: 0mm < B ≤ 1mm; and / or; the minimum radial dimension A of the first interval satisfies: 1mm < A ≤ 4mm.

[0012] In one embodiment of this utility model, the ratio of the radial length L of the second solder mark to the minimum radial dimension of the manifold is 0.27 to 0.3, wherein:

[0013] 11mm≤L≤12mm.

[0014] In one embodiment of the present invention, the ratio of the minimum radial dimension of the collector disk to the minimum radial dimension of the collector section is 0.9.

[0015] In one embodiment of the present invention, the collector plate is surrounded by a plurality of solder areas at intervals in the circumferential direction, and each solder area includes at least one second solder mark extending radially.

[0016] In one embodiment of the present invention, the second solder mark includes a second solder mark a and a second solder mark b. Each solder mark area includes at least two second solder marks a and at least one second solder mark b. The outer contours of the at least two second solder marks a form a fan-shaped area. At least one second solder mark b is located within the fan-shaped area and between two adjacent first solder marks a. One end of the second solder mark b that is radially away from the central hole is aligned with one end of the second solder mark a that is away from the central hole along the same circumferential path. The length of the second solder mark a is greater than the length of the second solder mark b.

[0017] In one embodiment of this utility model, the second solder mark a and / or the second solder mark b are straight or curved.

[0018] This utility model also provides a battery pack, including the cylindrical battery described above.

[0019] The beneficial effects of this utility model are as follows: The cylindrical battery proposed in this utility model has a first solder mark formed by welding the current collector and the terminal post, and a second solder mark formed by welding the current collector and the current collection part. There is a first gap between the second solder mark and the first solder mark, with a minimum radial dimension of A. There is a second gap between the second solder mark and the outer periphery of the current collector, with a radial dimension of B, where 0≤B / A≤1. In this way, the first and second solder marks are reasonably distributed on the limited area of ​​the current collector, and considering both gaps A and B, the DC internal resistance is reduced, the overall current carrying capacity of the current collector is improved, and the optimal current carrying effect is achieved. At the same time, the reasonable design of gaps A and B ensures that a certain safe distance is maintained between the second solder mark and the first solder mark, as well as between the second solder mark and the outer periphery of the current collector, avoiding the solder wire burn-through caused by the gap being too small during welding, thus improving the overall safety of the battery. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0021] In the attached diagram:

[0022] Figure 1 This is a partial cross-sectional view of a cylindrical battery provided in an embodiment of the present invention;

[0023] Figure 2 Provided in one embodiment of this utility model Figure 1 Schematic diagram of the middle electrode assembly;

[0024] Figure 3 Provided in one embodiment of this utility model Figure 1 Schematic diagram of the central flow disk Figure 1 ;

[0025] Figure 4 Provided in one embodiment of this utility model Figure 1 A magnified view of a portion of the image;

[0026] Figure 5 Provided in one embodiment of this utility model Figure 1 Schematic diagram of the central flow disk Figure 2 ;

[0027] Figure 6 A schematic diagram of the battery pack structure is provided for one embodiment of this utility model;

[0028] Figure 7 A schematic diagram of the structure of an electronic device provided for one embodiment of this utility model.

[0029] The attached figures are labeled as follows:

[0030] 1. Electronic device; 10. Battery pack; 101. Housing; 102. Housing cover; 11. Working part; 100. Cylindrical battery; 110. Casing; 111. End wall; 112. Side wall; 115. Terminal hole; 120. Electrode assembly; 1201. Center hole; 121. Positive electrode sheet; 1211. Positive current collector; 1212. Positive coated area; 1213. Positive uncoated area; 122. Separator; 123. Negative electrode sheet; 1231. Negative current collector; 1232. Negative coated area; 1233. Negative uncoated area; 124. Positive current collector; 1241. Positive stack; 140. Current collector plate; 143. First solder mark; 144. Second solder mark; 1441. Second solder mark a; 1441. Second solder mark b; 150. Terminal. Detailed Implementation

[0031] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0032] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0033] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the present invention. However, it will be apparent to those skilled in the art that embodiments of the present invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the present invention.

[0034] A cylindrical battery 100 typically includes a housing 110 and an internal electrode assembly 120. A terminal post 150 is provided on the housing 110 to realize the current transmission path of the battery. A current collector 140 is provided between the electrode assembly 120 (including the core / laminated assembly) and the terminal post 150 to realize the internal current conduction between the electrode assembly 120 (including the core / laminated assembly) and the terminal post 150.

[0035] To achieve current conduction, the current collector 140 typically needs to be soldered to the terminal post 150 and the electrode assembly 120 to achieve electrical conductivity. Regarding the soldering of these two components: Firstly, the characteristics of the terminal post 150 itself need to be considered. Specifically, the terminal post 150 needs to be fixedly and sealed to the housing 110, requiring good mechanical strength to maintain a stable connection with the housing 110 in the event of thermal runaway within the battery. Simultaneously, the thickness of the portion of the terminal post 150 to be soldered to the current collector 140 needs to be designed to ensure soldering quality while considering the impact on DC internal resistance after soldering, thus achieving a stable electrical connection with the current collector 140. Furthermore, the terminal post 150 is relatively small, and the soldering of the terminal post 150 and the current collector 140 needs to be completed within a small area. During soldering, the internal safety of the battery under high soldering energy within this small area must be considered. Secondly, when soldering to the electrode assembly 120, for safety design requirements and with a fixed penetration depth, a larger soldering area is needed to effectively reduce the internal DCR of the battery. In summary, how to reasonably design the welding penetration and welding area on the current collector 140 requires comprehensive consideration of battery performance such as safety performance, power performance, energy efficiency and cycle life, and is a crucial design issue.

[0036] In this application, the current collector 140 located between the electrode assembly 120 and the electrode post 150 has a first weld mark 143 formed by welding with the electrode post 150 and a second weld mark 144 formed by welding with the electrode assembly 120. It is understood that, since both are formed by welding, and more specifically, laser welding is used to minimize the weld resistance after welding. Laser welding typically uses high-frequency pulses, requiring consideration of the heat-affected zone during the welding process to reduce deformation and residual stress in the welded workpiece. The first weld mark 143 and the second weld mark 144 need a certain safety range, i.e., A+B+L, where A is the first interval between the second weld mark 144 and the first weld mark 143, B is the second interval between the second weld mark 144 and the outer periphery of the current collector 140, and L is the radial length L of the second weld mark 144. If B is too small, the laser may burn the surface of the electrode assembly 120; if A is too small, there is a risk of melting through the current collector 140. Therefore, the dimensions of A+B need to be considered comprehensively, and they need to be as large as possible while ensuring a safety baseline. That is, the first solder mark 143 and the second solder mark 144 are adjusted to a safer position in the radial direction. To solve this problem, the present invention provides the following solution.

[0037] Please see Figures 1-5 The present invention provides a cylindrical battery 100, comprising: a housing 110, a terminal post 150, an electrode assembly 120, and a current collector 140.

[0038] Please see Figure 1 The housing 110 forms a receiving space. The housing 110 includes an end wall 111 and a side wall 112 surrounding the end wall 111. As long as a stable sealing and electrical connection can be formed, the connection between the end wall 111 and the side wall 112 can be achieved in various ways, such as integral stamping, integral casting, or separate welding. The housing 110, enclosed by the end wall 111 and the side wall 112, forms a receiving space for accommodating the electrode assembly 120, electrolyte, and other necessary battery components.

[0039] Please see Figure 1 The end wall 111 is provided with a pole hole 115, and the pole 150 is installed in the pole hole 115 and is insulated from the end wall 111. The shape of the pole 150 can be any shape that is easy for those skilled in the art to imagine, including but not limited to a cross-section that can be circular, square, prismatic or irregular contour that can achieve stable conductivity. The shape of the pole hole 115 corresponds to the shape of the pole 150.

[0040] Please see Figures 1-2The electrode assembly 120 is housed within the housing space and is a component in the cylindrical battery 100 where an electrochemical reaction occurs. The housing 110 may contain one or more electrode assemblies 120. Exemplarily, in this embodiment, one electrode assembly 120 is disposed within the housing 110. Specifically, in this embodiment, the electrode assembly 120 includes a positive electrode 121, a negative electrode 123, and a separator 122 separating the positive and negative electrode 121 and the negative electrode 123. The positive electrode 121, the negative electrode 123, and the separator 122 are stacked and wound to form a core. The core has a central hole 1201 and a current collector located at the end of the electrode assembly 120 facing the terminal post 150.

[0041] Please see Figures 1-2 In this embodiment, to distinguish between the positive electrode 121 and the negative electrode 123, the positive electrode 121 may include a positive current collector 1211. The positive current collector 1211 includes a positive electrode coated area 1212 coated with active material and a positive electrode uncoated area 1213 (i.e., an empty foil) uncoated with active material. The positive electrode uncoated area 1213 extends out of the separator 122 along the axial direction of the cylindrical battery 100 to form a positive electrode tab. The positive electrode tab is bent and stacked towards the central axis of the cylindrical battery 100 to form a positive electrode stack 1241. To distinguish it from the current collector formed by the negative electrode, the current collector located on the positive electrode is called the positive current collector 124, and the positive current collector 124 is the positive electrode stack 1241. It should be noted that in the actual cylindrical battery 100 product, the positive electrode stack 1241 will form a resisting relationship with the inner ring portion of the core facing the terminal post 150, that is, the two are at least partially in contact with each other. The gap shown in the accompanying drawings of the embodiments of this utility model between the positive electrode stack 1241 and the inner ring portion of the winding core facing the pole post 150 does not indicate that such a gap exists in the actual product; the illustration is for illustrative purposes only.

[0042] Please continue reading. Figures 1-2 The negative electrode sheet 123 may include a negative electrode current collector 1231. The negative electrode current collector 1231 includes a negative electrode coated area 1232 coated with active material and a negative electrode uncoated area 1233 (i.e., empty foil) uncoated with active material. The negative electrode uncoated area 1233 extends out of the separator 122 along the axial direction of the cylindrical battery 100 to form a negative electrode tab. The negative electrode tab is bent and stacked towards the central axis of the cylindrical battery 100 to form a negative electrode stack. In order to distinguish it from the current collector formed by the positive electrode sheet, the current collector located on the negative electrode sheet is called the negative electrode current collector (not shown). The negative electrode current collector is the negative electrode stack.

[0043] A separator 122 is disposed between the positive electrode 121 and the negative electrode 123 to isolate the positive and negative active material layers. Taking a lithium-ion cylindrical battery 100 as an example, the positive current collector 1211 can be made of aluminum, and the positive active material layer includes positive active material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative current collector 1231 can be made of copper, and the negative active material layer includes negative active material, which can be carbon or silicon, etc. The substrate material of the separator 122 can be polypropylene (PP) or polyethylene (PE), etc. To protect and insulate the electrode assembly 120, an insulating film can also be wrapped around the electrode assembly 120. The insulating film can be synthesized from PP, PE, polyethylene terephthalate (PET), polyvinyl chloride (PVC), or other polymer materials.

[0044] Please see Figures 1-2 In this embodiment, the positive current collector 124 faces the end wall 111 of the housing 110 and is electrically connected to the electrode post 150, making the electrode post 150 positively charged. The negative current collector faces the other end of the housing 110, and the housing 110 is electrically connected to the negative current collector, thus making it negatively charged. However, in another embodiment, the negative current collector can be connected to the electrode post 150, and the positive current collector 124 can be connected to the housing 110. It should be noted that the structure of the side wall 112 facing away from the end wall 111 is not limited in this invention. For example, it can be a mechanical seal structure formed by sealing with a cover plate, or a welded seal structure formed by welding a cover plate to the side wall 112, but it is not limited thereto.

[0045] Please see Figure 1 and Figure 3 The current collector 140 is disposed inside the housing 110 and located between the electrode assembly 120 and the electrode post 150. The current collector 140 has a first solder mark 143 and a second solder mark 144. The first solder mark 143 is formed by welding the current collector 140 and the electrode post 150. The first solder mark 143 is distributed circumferentially, including but not limited to a continuously distributed arc shape, or other surrounding shapes. By distributing the first solder mark 143 circumferentially, a low-impedance uniform current path can be formed, enhancing mechanical stability.

[0046] Please see Figure 1 and Figure 3The second weld mark 144 is formed by welding the current collector 140 to the positive electrode current collector 124. The second weld mark 144 can be continuously distributed circumferentially or spaced out radially. In this embodiment, the second weld mark 144 can be distributed continuously circumferentially or spaced out radially. The continuous distribution of the second weld mark 144 circumferentially can form a low-impedance uniform current path, enhancing mechanical stability; the spaced out distribution of the second weld mark 144 radially can release electrode expansion stress, improve welding process tolerance, and reduce thermal damage. It can be flexibly selected according to the performance requirements of the battery in actual use.

[0047] Please see Figure 1 and Figure 3 The second solder mark 144 and the first solder mark 143 have a first gap, the minimum radial dimension of which is A. The second solder mark 144 and the outer periphery of the current collector 140 have a second gap, the radial dimension of which is B, 0≤B / A≤1. For example, B / A can be any value between 0 and 1, such as 0.2, 0.4, 0.6, 0.8, etc. In this way, the first solder mark 143 and the second solder mark 144 are reasonably distributed on the limited area of ​​the current collector 140. Taking into account both gap A and gap B, the DC internal resistance is reduced, the overall current carrying capacity of the current collector 140 is improved, and the best current carrying effect is achieved. At the same time, the reasonable design of gap A and gap B ensures that a certain safe distance is maintained between the second solder mark 144 and the first solder mark 143, as well as between the second solder mark 144 and the outer periphery of the current collector 140, to avoid the solder line burn-through caused by the gap being too small during welding, thereby improving the overall safety of the battery.

[0048] The specific analysis process of the influence of the first gap A between the second solder mark 144 and the first solder mark 143, and the second gap B between the second solder mark 144 and the outer periphery of the collector 140 on the DCR (DC internal resistance) is as follows:

[0049] The effect of the first gap A on DCR: the contact resistance R at the second solder mark position 144 c Analysis of the influence of dimension A: R c =ρ c / A c , where R c For contact resistance, ρ c A is the contact impedance. c To ensure effective contact area; as the first interval A increases, the welding area between the annular solder area where the second solder mark 144 is located and the positive current collector 124 of the electrode assembly 120 will decrease, leading to an increase in contact resistance within the annular solder area. Considering that the first interval A is related to the number of electrode tabs welded, insufficient first interval A may increase resistance, R. c =ρ c / ((N×A c)×(1+α)), where N is the number of electrodes involved in electrode welding, and α is the material coefficient of the electrodes). Actual measurements show that when the first interval A decreases from 1.5mm to 1.0mm, R c It will increase by about 15% due to the decrease in the number of electrodes involved in welding.

[0050] Path impedance R p Analysis of the influence of dimension A: R p =ρL o / S, where S is the flow area formed by welding, L o The length of the current path is ρ, which is the radial length of the second solder mark 144 on the stack 1241. ρ is the material density of the electrode tab. As the first gap A increases, the current flows from the electrode post 150 to the electrode tab along the path L. o If it increases, then R p It will increase based on the same flow area.

[0051] Based on the above analysis, it can be seen that increasing the distance of the first interval A will affect the contact resistance R to a certain extent. c and path impedance R p This is not conducive to optimizing the internal resistance of the battery.

[0052] The specific analysis process of the impact of the second interval B on DCR is as follows:

[0053] Given that the parallel resistance R = 1 / (∑(1 / R) i It can be understood that when multiple resistors R1, R2, R3..., R... n When connected in parallel, the reciprocal of the parallel resistance R is equal to the sum of the reciprocals of each individual resistance. Assume the radius of the circular collector 140 is d, and the radius of the first solder mark 143 is R. in The radial length of the second weld mark 144 is L. Based on the positional relationship, we know that: A + B + L = dR in That is, A+B=dR in -L;R∝1 / A+1 / L 2 That is, R is inversely proportional to the first interval A, and also proportional to L. 2 The length of L is inversely proportional to the length of the parallel resistor R. Therefore, while ensuring the length of L, the first interval A needs to be maximized to reduce the parallel resistance R. Assuming that the second interval B approaches 0 in an ideal situation, it is known that when L is maximized, R is minimized, so B / A≈0. However, the longer L is, the smaller R will be. Assuming that the radial dimension of the area where solder can be distributed (i.e., the area with radial dimension A+B+L) is l, that is, dR in =1, when L approaches dR in When A+B≈0, and A and B are both equal to 0, AB≈0, it is obvious that A / B≈1; therefore, 0≤B / A≤1.

[0054] As one embodiment of this application, the circular collector 140 has a radius d of 20 mm, and the central hole 1201 has a radius R. hole The radius d of the first solder mark 143 is 2.5mm. in =3.5mm (the radius of the first weld mark 143 is taken into account that the area near the center hole 1201 needs to maintain a certain safe distance from the position of the first weld mark 143 during laser welding), then A+B+L=20-3.5=16.5mm. To ensure engineering capability and tolerance, the minimum value of the second interval B can be close to 0.5mm, then A+L=16mm. As can be seen from the above, since the first interval A should not be too small, L should not be too small either, but the lengths of the two are mutually exclusive. According to R∝1 / A+1 / L 2 The formula, optimized by R, and the minimum value are used to obtain the derived formula: With the first interval A = 4.2 mm and L = 11.8 mm, it can be seen that the maximum value of the first interval A is limited to 4 mm, while the maximum value of L is 12 mm, which can ensure that R obtains a better state.

[0055] Please see Figure 1 and Figure 3 To take all factors into consideration, the minimum size of the second gap B needs to be controlled as small as possible to improve the design space for A+L, while also taking into account the impact of the second gap B on the parallel resistance and the risk of burns to the electrode assembly 120. The maximum radial size B of the second gap can satisfy: 0mm < B ≤ 1mm, such as any value between 0mm and 1mm, such as 0.2mm, 0.4mm, 0.8mm, etc. In a preferred embodiment, when B = 0.5mm, A = 4.2mm and L = 11.8mm.

[0056] Please see Figure 1 and Figure 3 The central area of ​​the collector plate 140 is an area with higher safety requirements. Therefore, this location is the area adjacent to the first solder mark 143 and the second solder mark 144. In order to ensure a safer design space and to take into account the impact of the first gap A on impedance and the risk of penetration, the minimum radial dimension A of the first gap can satisfy: 1mm < A ≤ 4mm, such as 1.5mm, 3mm, 3.8mm, etc., any value between 1mm and 4mm.

[0057] Please see Figure 1 and Figure 3To ensure the length of the flow path and the overall flow performance of the collector plate 140, the radial length L of the second solder mark 144 needs to be considered. The ratio of the radial length L of the second solder mark 144 to the minimum radial dimension of the collector plate 140 can be 0.27 to 0.3. In specific implementation, 11mm≤L≤12mm, such as 11mm, 11.4mm, 11.8mm, 12mm, etc., any value between 11mm and 12mm.

[0058] In summary, 0mm < B ≤ 1mm; 1mm < A ≤ 4mm; 11mm ≤ L ≤ 12mm are taken into account to accommodate the risks of electrode assembly 120 burning, solder melt-through, and the overall current flow performance of manifold 140.

[0059] Existing cylindrical batteries have terminals that are only welded to the current collector, reducing the welding of some stacked parts and current collectors, which reduces the parallel circuits and increases the DCR (DC internal resistance). Furthermore, due to the reduction in the welding of the first inner ring solder and some stacked parts, the current density difference between the inside and outside of the electrode assembly is aggravated during charging. In addition, due to the fewer parallel circuits on the inside and the higher polarization, lithium plating is more likely to occur on the inner ring, which can lead to thermal runaway. To solve this problem, in this embodiment, the first solder mark 143 can be formed by welding the current collector 140 to the positive current collector 124 and the terminal 150. That is, at the welding position 15031 where the first solder mark 143 is formed, the first solder mark 143 simultaneously welds and connects the terminal 150, the current collector 140 and the positive current collector 124, realizing the simultaneous connection of three components in one welding pool. In specific implementation, the first solder mark 143 is formed at the welding position 15031, from the side of the terminal 150 away from the current collector 140, to the terminal 150, the current collector 140 and the positive current collector 124 in one welding. The simultaneous welding of the three components increases the parallel circuit, reduces the DCR (DC internal resistance), improves the overcurrent capacity under the same temperature rise requirement, and expands the heat conduction area, enhances heat dissipation, and allows heat to be conducted to the terminal 150 or the housing 110 more quickly.

[0060] To avoid short-circuit risks caused by burning the separator 122 in the central hole 1201 area during welding and to improve overall battery safety, this embodiment comprehensively considers factors such as the penetration depth of the first weld 143, the coverage of the heat-affected zone, and process tolerances. Regarding the penetration depth control of the first weld 143, since the laser needs to penetrate the electrode post 150 and reach deep into the core, the thickness h2 of the electrode post 150 along the axial direction of the cylindrical battery is typically 0.3mm to 0.8mm. If the first weld 143 is too small, it will lead to insufficient fusion of the stacked parts. Regarding the coverage of the heat-affected zone, the first weld 143 needs to completely cover the central hole 1201 and extend outwards, so that the heat-affected zone can simultaneously melt the roots of 3 to 14 electrode layers, achieving effective welding and contributing to the reduction of DCR. If the design is less than 3 electrode layers, effective welding cannot be guaranteed overall, and there is a risk of incomplete welding or broken welding. Regarding process tolerances, a 1mm to 2mm allowance is reserved for the weld line length to compensate for assembly / alignment deviations. Please refer to [link to relevant documentation]. Figure 4 In this embodiment, the radius of the central hole 1201 is defined as R. hole The radius of the center of the first solder mark 143 is R. in At the welding position where the first solder mark is formed, the thickness of the tab of the positive electrode stack 1241 is T, the thickness of the current collector 140 along the axial direction of the cylindrical battery 100 is h1, and the thickness of the electrode post 150 along the axial direction of the cylindrical battery 100 is h2, R hole and R in satisfy:

[0061] R in =R hole +1.0 × Melting Depth = R hole +h1+h2+M×T, where T, h1, h2, and R are... in and R hole The units are all mm, and M is the number of layers of the electrode lugs involved in welding, which is a natural number and 3 ≤ M ≤ 10. For example, M is 3, 4, 5, 6, 7, 8, 9, 10; thus R hole and R in By satisfying the above formula, effective welding with the stacked part 1241 can be achieved at the first solder mark 143, which reduces DCR, ensures welding yield, improves welding safety, and enhances the overall safety of the battery.

[0062] The ratio of the minimum radial dimension of the current collector 140 (i.e., the diameter of the current collector 140) to the minimum radial dimension of the positive current collector 124 can be 0.9. That is, the diameter of the current collector 140 is smaller than the minimum radial dimension of the positive current collector 124, so that the current collector 140 exposes a certain edge end face relative to the positive current collector 124, which makes it convenient for the current collector 140 to be inserted into the housing during installation.

[0063] Please see Figure 3The collector plate 140 may have multiple solder areas spaced around it in the circumferential direction. Each solder area includes at least one second solder 144 extending radially to evenly distribute the second solder 144, which is beneficial to the uniform distribution of DCR and ensures the overall current carrying capacity of the collector plate 140. To further optimize the solder area, the second solder mark 144 may include a second solder mark a1441 and a second solder mark b1441. Each solder area includes at least two second solder marks a1441 and at least one second solder mark b1442. The outer contours of the at least two second solder marks a1441 form a fan-shaped area. At least one second solder mark b1442 is located within the fan-shaped area and between two adjacent second solder marks a1442. One end of the second solder mark b1442 that is radially away from the center hole 1201 is aligned with one end of the second solder mark a1441 that is away from the center hole 1201 along the same circumferential path. The length of the second solder mark a1441 is greater than the length of the second solder mark b1442, so as to distribute the second solder marks 144 more evenly, which is more conducive to the uniform distribution of DCR and better ensures the overall flow capacity of the collector plate 140.

[0064] Please see Figure 3 and Figure 5 The second solder mark a1441 and / or the second solder mark b1442 can be straight or curved. Compared with the straight shape, the curved shape can better increase the actual length of L within the limited area of ​​the collector plate 140, ensuring the length of the flow path and ensuring the overall flow performance of the collector plate 140.

[0065] Please see Figure 6 This utility model also provides a battery pack 10, which includes the cylindrical battery 100 described above. In one embodiment of the battery pack 10, the battery pack 10 includes a housing 101, a cover 102, and multiple cylindrical batteries 100. The multiple cylindrical batteries 100 are placed in the housing 101 and connected in series or parallel, or a combination of series and parallel connections. The cover 102 seals the housing 101 to protect the multiple cylindrical batteries 100. It should be noted that, in addition to the cylindrical battery 100 of this utility model, the battery pack 10 may also include a thermal management system, circuit board, etc. The battery pack 10 can be a battery module, a battery pack, an energy storage cabinet, etc., used to store or supply electricity to electronic devices; these will not be described in detail here.

[0066] Please see Figure 7The cylindrical battery 100 and battery pack 10 provided by this utility model can be applied to an electronic device 1, which may include the aforementioned cylindrical battery 100. The working part 11 is electrically connected to the cylindrical battery 100 to obtain power support. As an example, the electronic device 1 is a vehicle, which may be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles may be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, but are not limited thereto. The working part 11 is the vehicle body, with the cylindrical battery 100 disposed at the bottom of the vehicle body, providing power support for the vehicle's movement or the operation of electrical components within the vehicle. However, in other embodiments, the electronic device 1 may also be a mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, and power tool, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; the working part 11 may be a unit component capable of obtaining power from the cylindrical battery 100 and performing corresponding work, such as a fan blade rotation unit or a vacuum cleaner suction unit. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric boat toys, and electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the aforementioned electronic device 1.

[0067] In summary, the cylindrical battery, battery pack, and electronic device of this utility model optimize the solder pattern layout based on the welding position relationship between the first and second solder marks, improve the current carrying capacity, and achieve the optimal range between the safety baseline 0≤B / A≤1 and the overall current carrying capacity requirement of the current collector, thus achieving a balance between welding process and electrochemical performance.

[0068] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A cylindrical battery, characterized in that, include: A housing forms a receiving space, the housing includes an end wall, and an pole post hole is provided on the end wall; The electrode post is installed in the electrode post hole and is insulated from the end wall; An electrode assembly is housed within the housing space. The electrode assembly includes a positive electrode, a negative electrode, and a separator separating the positive electrode and the negative electrode. The positive electrode, the negative electrode, and the separator are stacked and wound to form a core. The core is provided with a central hole and a current collector located at the end of the electrode assembly facing the electrode post. A current collector is disposed within the housing and located between the electrode assembly and the electrode post; The current collector has a first weld mark and a second weld mark. The first weld mark is formed by welding the current collector to the pole post and is distributed circumferentially. The second weld mark is formed by welding the current collector to the current collection part. There is a first gap between the second weld mark and the first weld mark. The minimum radial dimension of the first gap is A. There is a second gap between the second weld mark and the outer periphery of the current collector and the radial dimension of the second gap is B. 0≤B / A≤1.

2. The cylindrical battery according to claim 1, characterized in that, The first solder mark is formed by welding the current collector plate, the current collector part, and the electrode post; the first solder mark is formed at the welding position by welding the electrode post, the current collector plate, and the current collector part together in one operation from the side of the electrode post away from the current collector plate.

3. The cylindrical battery according to claim 1, characterized in that, The first solder mark is a continuously distributed arc shape, and the second solder mark is continuously distributed circumferentially or spaced apart radially; the positive electrode and the negative electrode include a current collector, the current collector includes a coated area coated with active material and an uncoated area uncoated with active material, the uncoated area extends out of the separator along the axial direction of the cylindrical battery to form a tab, the tab is bent and stacked towards the central axis of the cylindrical battery to form a stacked part, and the current collector is the stacked part; The radius of the central hole is defined as R. hole The radius of the first solder mark is R. in At the welding position where the first solder mark is formed, the thickness of the tab of the stacked portion is T, the thickness of the current collector along the axial direction of the cylindrical battery is h1, the thickness of the electrode along the axial direction of the cylindrical battery is h2, and the thickness of R... hole and the R in satisfy: R in =R hole +h1+h2+M×T, where T, h1, h2, and R are... in and R hole The units are all mm, and M is the number of layers of the electrode lugs involved in the welding, which is a natural number and 3≤M≤10.

4. The cylindrical battery according to claim 1, characterized in that, The maximum radial dimension B of the second interval satisfies: 0mm < B ≤ 1mm; and / or, the minimum radial dimension A of the first interval satisfies: 1mm < A ≤ 4mm.

5. The cylindrical battery according to claim 4, characterized in that, The ratio of the length L of the second solder mark along the radial direction to the minimum radial dimension of the manifold is 0.27 to 0.3, wherein: 11mm≤L≤12mm.

6. The cylindrical battery according to claim 1, characterized in that, The ratio of the minimum radial dimension of the collector plate to the minimum radial dimension of the collector section is 0.

9.

7. The cylindrical battery according to claim 1, characterized in that, The collector plate is circumferentially surrounded by multiple solder pads, each solder pad including at least one second solder pad extending radially.

8. The cylindrical battery according to claim 7, characterized in that, The second solder mark includes a second solder mark a and a second solder mark b. Each solder mark area includes at least two second solder marks a and at least one second solder mark b. The outer contours of the at least two second solder marks a form a fan-shaped area. At least one second solder mark b is located within the fan-shaped area and between two adjacent second solder marks a. The end of the second solder mark b facing away from the central hole along the radial direction is aligned with the end of the second solder mark a facing away from the central hole along the same circumferential path. The length of the second solder mark a is greater than the length of the second solder mark b.

9. The cylindrical battery according to claim 8, characterized in that, The second solder mark a and / or the second solder mark b are straight or curved.

10. A battery pack, characterized in that, Includes the cylindrical battery as described in any one of claims 1 to 9.

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