Cylindrical battery, battery pack, and electronic device

Abstract

The utility model provides a kind of cylindrical battery, battery pack and electronic device, cylindrical battery includes: shell, pole, electrode assembly and current collector plate.The shell includes end wall, and end wall is provided with pole hole;Pole is installed in pole hole and is insulated with end wall;Electrode assembly includes positive plate, negative plate and diaphragm spacing positive plate and negative plate, and positive plate, negative plate and diaphragm are stacked and wound to form roll core, and roll core is provided with center hole and current collecting portion located at the end of electrode assembly facing pole;Current collector plate is set in shell, and current collector plate has first solder mark and second solder mark, and second solder mark is formed by welding current collector plate and current collecting portion of electrode assembly;First solder mark is formed by welding current collector plate and current collecting portion and pole, and first solder mark is distributed along circumference, and the minimum radial distance of first solder mark from the central axis of center hole is R, and the radius of center hole is R hole , R-R hole ≥1mm, and the present cylindrical battery can improve the technical problems of poor overcurrent capacity and low safety of existing cylindrical batteries.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a cylindrical battery, battery pack and electronic device. 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. The current-carrying capacity and safety of existing cylindrical batteries need improvement. Utility Model Content

[0004] In view of the shortcomings of the prior art, the present invention provides a cylindrical battery, a battery pack and an electronic device to improve the technical problems of poor overcurrent capacity and low safety of 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 solder mark and a second solder mark. The second solder mark is formed by welding the current collector to the current collection part of the electrode assembly. The first solder mark is formed by welding the current collector to the current collection part and the electrode post. The first solder mark is distributed circumferentially. The minimum radial distance of the first solder mark from the central axis of the central hole is R, and the radius of the central hole is R. hole RR hole ≥1mm.

[0007] 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 distributed at intervals along the radial direction of the electrode assembly; the positive electrode sheet and the negative electrode sheet 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;

[0008] Define the radius of the first solder joint center as R. in At the welding position where the first solder mark is formed, the thickness of the tab within the stack is T, the thickness of the current collector along the axial direction of the cylindrical battery is h1, and the thickness of the terminal post along the axial direction of the cylindrical battery is h2; the first solder mark is formed at the welding position by welding the terminal post, current collector, and current collector together in one operation from the side of the terminal post away from the current collector, and R hole and R in satisfy:

[0009] R in =R hole +h1+h2+M×T, where T, h1, h2, and R are... in and R hole The units are all mm. M is the number of layers of the electrode lugs involved in the welding, which is a natural number, and 3≤M≤10.

[0010] In one embodiment of this utility model, the current collector is located on the side of the electrode assembly near the electrode post. The electrode post is provided with an annular mounting wall that mates with the electrode post hole of the end wall and a welding wall that is connected to the end of the mounting wall near the current collector and extends radially. The inner side wall of the mounting wall along the radial direction and the side wall of the welding wall opposite to the motor assembly form a groove with an opening. The welding wall has a welding position in the groove. The welding wall is welded to the current collector and the current collection part at the welding position to form a first weld mark. The groove width is defined as N, and the maximum radial width of the first weld mark is defined as C, where the units of N and C are both mm. The groove width N and the maximum radial width C of the first weld mark satisfy:

[0011]

[0012] In one embodiment of the present invention, at the welding position where the first solder mark is formed, the number of stacked layers of the inner tab of the stacked portion is D, which is a natural number, and 16≥D≥10;

[0013] And / or, define the arc center angle of the first solder mark as θ, 180°≤θ<360°.

[0014] In one embodiment of this utility model, 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. The current collector is a stacked part. The stacking height of the stacked part along the axial direction of the cylindrical battery is h3, where h3 is 0.1 mm to 0.5 mm.

[0015] In one embodiment of this utility model, at the welding position where the first solder mark is formed, the thickness h1 of the current collector along the axial direction of the cylindrical battery is 0.3mm to 1.0mm; the thickness h2 of the electrode along the axial direction of the cylindrical battery is; and the penetration depth of the first solder mark is h4, wherein:

[0016] h4 satisfies: h1+h2≤h4≤h1+h2+h3;

[0017] And / or, the ratio of h4 to the sum of h1, h2, and h3 is greater than 90%;

[0018] The units for h1, h2, h3, and h4 are all mm.

[0019] In one embodiment of this utility model, at the welding position where the first solder mark is formed, the welding area of ​​the first solder mark is defined as S, and the penetration depth of the first solder mark is h4; S satisfies:

[0020]

[0021] Where: U is the voltage applied across the welding electrodes during welding, in volts (V); I is the current flowing through the welding circuit during welding, in amperes (A); t is the duration of the welding current, in seconds (s); c is the amount of heat absorbed by a unit mass of manifold material to raise its temperature by 1 Kelvin, in j; ΔT is the temperature rise of the welding area relative to its initial temperature during welding, in degrees Celsius (°C); and S is in mm. 2 The unit of h4 is mm.

[0022] In one embodiment of the present invention, at the welding position where the first solder mark is formed, the number of welding layers M between the collector plate and the inner tab of the stacked portion accounts for 0.18 to 1 of the total number of inner tab layers D of the stacked portion.

[0023] This utility model provides a battery pack, including the cylindrical battery described above.

[0024] This utility model also provides an electronic device, including the cylindrical battery described above.

[0025] 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, current collector portion, and terminal post. That is, at the welding position where the first solder mark is formed, the first solder mark simultaneously welds and connects the terminal post, current collector, and current collector portion, achieving simultaneous connection of three components in a single welding pool. This increases the parallel circuit, reduces DCR (DC internal resistance), improves the overcurrent capacity under the same temperature rise requirement, and expands the heat conduction area, enhancing heat dissipation and allowing heat to be conducted to the terminal post / casing more quickly. The first solder mark is distributed circumferentially, and the minimum radial distance from the first solder mark to the center of the central hole is R, with the radius of the central hole being R. hole RR hole ≥1mm, meaning the diameter of the first solder mark is larger than the diameter of the center hole, and the two maintain a safe distance of more than 1mm. This allows the first solder mark on the inner ring to participate in current flow, improving the overall current flow capacity of the current collector. At the same time, the first solder mark maintains a certain safe distance from the center hole to prevent the laser from approaching the center hole during the process and causing burns to the tabs. It also avoids the risk of short circuit caused by burning the separator in the center hole area during welding, thus improving the overall safety of the battery. Attached Figure Description

[0026] 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.

[0027] In the attached diagram:

[0028] Figure 1 This is a partial cross-sectional view of a cylindrical battery provided in an embodiment of the present invention;

[0029] Figure 2 Provided in one embodiment of this utility model Figure 1 Schematic diagram of the middle electrode assembly;

[0030] Figure 3 Provided in one embodiment of this utility model Figure 1 Schematic diagram of the central flow disk;

[0031] Figure 4 Provided in one embodiment of this utility model Figure 1 Local magnification Figure 1 ;

[0032] Figure 5 Provided in one embodiment of this utility model Figure 1 Local magnification Figure 2 ;

[0033] Figure 6 A schematic diagram of the battery pack structure is provided for one embodiment of this utility model;

[0034] Figure 7 A schematic diagram of the structure of an electronic device provided for one embodiment of this utility model.

[0035] The attached figures are labeled as follows:

[0036] 1. Electronic device; 10. Battery pack; 101. Housing; 102. 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 plate; 1211. Positive current collector; 1212. Positive electrode coated area; 1213. Positive electrode uncoated area; 122. Separator; 12 3. Negative electrode sheet; 1231. Negative electrode current collector; 1232. Negative electrode coated area; 1233. Negative electrode uncoated area; 124. Positive electrode current collector; 1241. Positive electrode stacking part; 140. Current collector plate; 143. First solder mark; 144. Second solder mark; 150. Terminal post; 1501. Groove; 1502. Mounting wall; 1503. Welding wall; 15031. Welding position; 2. Rubber plug; 21. Stop edge. Detailed Implementation

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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 welding to reduce deformation and residual stress in the welded workpiece. Existing cylindrical batteries only weld the electrode post to the current collector, reducing the welding of part of the stack and the current collector, resulting in fewer parallel circuits and an increased DCR (DC internal resistance). Furthermore, due to the reduction in the welding of the inner ring first weld mark to part of the stack, the uneven current density between the inside and outside of the electrode assembly is exacerbated during charging. Also, due to the fewer parallel circuits on the inner side and the higher polarization, lithium deposition is easily achieved in the inner ring, leading to thermal runaway. To solve this problem, this utility model provides the following solution.

[0043] Please see Figures 1-5The present invention provides a cylindrical battery 100, comprising: a housing 110, a terminal post 150, an electrode assembly 120, and a current collector 140.

[0044] 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.

[0045] 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.

[0046] Please see Figures 1-2 The 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.

[0047] Please see Figures 1-2In this embodiment, in order 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., 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. In order 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 forms an abutting relationship between the inner ring portion of the core and the end face of the negative electrode sheet 123 and / or the separator 122 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 this utility model between the positive electrode stack 1241 and the inner ring portion of the core facing the terminal post 150 does not indicate the existence of such a gap in the actual product; the illustration is for illustrative purposes only.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] Please see Figure 1 and Figure 3 The current collector 140 is disposed within the housing 110 and located between the electrode assembly 120 and the terminal post 150. The current collector 140 has a first solder mark 143 and a second solder mark 144. The second solder mark 144 is formed by welding the current collector 140 to the current collecting portion of the electrode assembly 120. The second solder mark 144 can be continuously distributed circumferentially or spaced out radially. In this embodiment, the second solder mark 144 can be distributed continuously circumferentially or spaced out radially. The continuous distribution of the second solder mark 144 circumferentially can form a low-impedance uniform current path, enhancing mechanical stability; the spaced out distribution of the second solder 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.

[0052] Please see Figure 1 and Figure 3The first weld mark 143 is formed by welding the current collector 140 to the positive current collector 124 and the electrode post 150. That is, at the welding position 15031 where the first weld mark 143 is formed, the first weld mark 143 simultaneously welds and connects the electrode post 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 weld mark 143 at the welding position 15031, from the side of the electrode post 150 away from the current collector 140, connects the electrode post 150, the current collector 140 and the positive current collector 124. The current collector 124 is welded once, and the three are welded together at once to form an increased parallel circuit, which reduces the DC internal resistance (DCR). Under the same temperature rise requirement, the current carrying capacity is improved, and the heat conduction area is increased, which enhances heat dissipation and allows heat to be carried out to the terminal 150 or the housing 110 more quickly. 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, which enhances mechanical stability.

[0053] Please see Figure 4 The minimum radial distance R between the first solder mark 143 and the central axis of the central hole 1201, and the radius R of the central hole 1201. hole RR hole ≥1mm, RR hole For example, the diameter can be 1mm, 1.5mm, 2mm, 2.5mm, 3mm, etc., that is, the diameter of the first solder mark 143 is at least larger than the diameter of the center hole 1201, and the two maintain a safe distance of more than 1mm. This allows the inner ring first solder mark 143 to participate in the current flow, improving the overall current flow capacity of the current collector 140. At the same time, the first solder mark 143 and the center hole 1201 maintain a certain safe distance to prevent the laser from approaching the center hole 1201 during the process and causing the electrode tab to be burned through. It also avoids the risk of short circuit caused by burning the separator 122 in the area of ​​the center hole 1201 during welding, thus improving the overall safety of the battery.

[0054] As an example of this application, please refer to Figure 4 In this embodiment, after the first solder mark 143 is welded, the distance R from the inner ring of the first solder mark 143 to the central axis O is 4.4 mm, the distance from the outer ring of the first solder mark 143 to the central axis O is 5.4 mm, and the weld width C is approximately 1 mm; the diameter of the central hole 1201 is 2R. holeThe groove width N (i.e., diameter) of the groove 1501 of the electrode post 150 is 11mm; the theoretical weldable width of the first solder mark 143 in the groove 150 is 3mm; considering that in some embodiments, a liquid injection hole needs to be provided in the groove 1501, and a rubber plug 2 will be installed on the liquid injection hole, the welding width of the first solder mark 143 can be controlled between 1 and 3mm; considering that in order to stop the rubber plug 2 from falling out in the axial direction, a stop edge 21 (located on the lower side of the bottom wall of the groove 1501, to achieve a stop in the axial direction away from the electrode assembly 120) is usually provided against the bottom wall of the groove 1501; considering the influence of the stop edge 21, the theoretical weldable width of the first solder mark 143 is reduced to 1 to 2mm. Taking into account the risk factors—the increase in welding power will increase the safety distance between the center hole 1201 and the first weld mark 143, and considering the process tolerance fluctuation of 0-1mm; without considering the structure of the rubber stopper 2 and the stop edge 21, the width range of the first weld mark 143 is 1-2mm; based on the above relationship, it can be seen that when the diameter of the groove 1501 of the pole post 150 is N, the diameter of the center hole 1201 is 2R. hole At that time, the radial width C of the first solder mark 143 should be: Due to the existing market 5≤2R hole ≤7, therefore When N→46mm, C=C max ,at this time

[0055] Although the application states that as long as the diameter of the first weld mark 143 is greater than the diameter of the central hole 1201 and the two are kept at a safe distance of more than 1 mm, the risk of short circuit caused by burning the separator 122 in the central hole 1201 area during welding can be avoided, thus improving the overall safety of the battery, in order to achieve better results, factors such as the melting depth of the first weld mark 143, the coverage of the heat-affected zone, and the process tolerance must be comprehensively considered. In terms of controlling the melting depth of the first weld mark 143, since the laser needs to penetrate the electrode post 150, the thickness h2 of the electrode post 150 at the welding position along the welding direction (in this application, that is, the axial direction of the cylindrical battery) is 0.3 mm to 0.8 mm. If the melting depth of the first weld mark 143 is too small, the stacked part 1241 will not be fully fused. Regarding heat-affected zone (HAZ) coverage, the first weld mark 143 must completely cover the area outside the safe zone extending outward from the center hole 1201 (the area extending radially outward 1mm from the edge of the center hole 1201), and ensure that the HAZ can simultaneously melt the roots of 3 to 14 layers of tabs to achieve effective welding and contribute to reducing DCR. If the design has fewer than 3 layers of tabs, overall effective welding cannot be guaranteed, and there is a risk of incomplete welding or weld breakage. Regarding process tolerance, a weld line position tolerance of 1mm to 2mm is reserved to compensate for assembly / alignment deviations.

[0056] Please see Figures 4-5The present invention provides the following solution in one embodiment.

[0057] Define the radius of the center of the first solder mark 143 as R. in At the welding position 15031 where the first solder mark 143 is formed, the thickness of the tab in 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:

[0058] 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 can be 3, 4, 5, 6, 7, 8, 9, or 10; thus R hole and R in By satisfying the above formula, effective welding can be achieved at the first solder mark 143, which can reduce DCR, ensure welding yield, improve welding safety, and enhance the overall safety of the battery.

[0059] Please see Figures 4-5 The collector plate 140 can be located on the side of the electrode assembly 120 near the pole post 150. The pole post 150 is provided with an annular mounting wall 1502 that mates with the pole post hole 115 of the end wall 111, and a welding wall 1503 that is connected to one end of the mounting wall 1502 near the collector plate 140 and extends radially. The inner side wall 112 of the mounting wall 1502 and the side wall 112 of the welding wall 1503 opposite to the motor assembly 120 form a groove 1501 with an opening. The welding wall 1503 has a welding position 15031 in the groove 1501. The welding wall 1503 is welded to the collector plate 140 and the collector part at the welding position 15031 to form a first weld mark 143. The groove width of the groove 1501 is defined as N. In one embodiment, the groove 1501 is a cylindrical groove, the groove width N is the diameter of the groove 1501, and the maximum radial width of the first weld mark 143 is C, where N, C, and R are... hole The units are all mm. The groove width N and the maximum radial width C of the first weld mark 143 satisfy:

[0060] Thus, the maximum radial width C of the first solder mark 143 is selected within this range, which comprehensively considers the overall flow capacity of the collector plate 140 and the safety of the first solder mark 143 and the center hole 1201.

[0061] The distance and the welding power of the first solder mark 143 further improve the overall safety of the battery.

[0062] Please see Figure 4 In one embodiment of this utility model, the stacking height of the positive electrode stacking portion 1241 along the axial direction of the cylindrical battery 100 can be h3, where h3 is 0.1mm to 0.5mm. For example, h3 can be any value between 0.1mm and 0.5mm, such as 0.1mm, 0.3mm, or 0.5mm. At the welding position 15031 where the first solder mark 143 is formed, the number of stacked layers of the inner tab of the positive electrode stacking portion 1241 is D, which is a natural number, and 16≥D≥10. For example, D is 10, 12, or 15, etc., to ensure the safe number of welding layers of the electrode post 150, the current collector 140, and the positive electrode stacking portion 1241, to ensure the overall current carrying capacity of the current collector 140, while avoiding solder burn-through and preventing the diaphragm 122 in the central hole 1201 area from being burned by excessive welding power. Furthermore, the number of welding layers M between the current collector 140 and the inner tab of the positive electrode stack 1241 can be 0.18 to 1 of the total number of layers D of the inner tab of the positive electrode stack 1241, for example, any value between 0.18 and 1 such as 0.25, 0.5, 0.8, etc., in order to achieve effective welding and avoid burn-through.

[0063] Please see Figure 3 The first weld mark 143 should not be a complete circle, as the end is prone to burn-through, which will damage the sealing structure. In order to take into account DCR, the arc center angle of the first weld mark 143 can be defined as θ, 180°≤θ<360°, such as 190°, 300°, 350°, etc., any value between 180° and 360°.

[0064] To facilitate control over the welding quality of the first solder mark 143 and reduce welding risks, and considering cost and the energy density of the electrode assembly 120, the thickness h1 of the current collector 140 is taken into account. If the thickness of the current collector 140 is too low, it is easy to weld through; if the thickness is too high, it cannot be welded to the electrode tab. Please refer to [link to relevant documentation]. Figure 4 In this embodiment, at the welding position 15031 where the first solder mark 143 is formed, the thickness h1 of the current collector 140 along the axial direction of the cylindrical battery 100 is 0.3mm to 1.0mm, for example, any value between 0.3mm and 1.0mm such as 0.3mm, 0.7mm, 1.0mm, etc.

[0065] When the penetration depth h4 of the first weld mark 143 is too large, hot cracks are prone to occur at the joint surface, and the tensile strength of the weld will be significantly reduced, easily causing the molten pool to collapse and forming large spatter and pit defects; please refer to Figure 4To avoid the aforementioned defects, this embodiment comprehensively considers that the penetration depth of the first solder mark 143 is h4, and at the welding position 15031 where the first solder mark 143 is formed, the thickness of the electrode post 150 along the axial direction of the cylindrical battery 100 is h2; the penetration depth of the first solder mark 143 is h4, wherein:

[0066] h4 satisfies: h1+h2≤h4≤h1+h2+h3, and the ratio of h4 to the sum of h1, h2, and h3 is greater than 90%. The units of h1, h2, h3, and h4 are all mm. This reasonable control of the penetration depth h4 ensures the overall current-carrying capacity of the current collector 140 while further improving welding safety and effectively avoiding the aforementioned defects. The test method for penetration depth h4 is as follows: the depth of metal melting and resolidification during the welding process is measured from the welding interface (i.e., the contact surface between the current collector 140 and the end face of the motor assembly 120) in the vertical direction (i.e., the axial direction of the cylindrical battery 100) into the motor assembly 120.

[0067] The electrode assembly 120 is designed with a temperature safety value of ≤60℃. To prevent the temperature of the welding area of ​​the first solder mark 143 from exceeding 60℃, the welding area S and penetration depth h4 of the first solder mark 143 must be large enough to disperse heat and limit temperature rise, thereby ensuring the safety of the core. The welding area of ​​the first solder mark 143 is defined as S, where S satisfies:

[0068]

[0069] Where: U is the voltage applied across the welding electrodes during welding, i.e., the voltage output by the welding power source, in volts (V); I is the current flowing through the welding circuit during welding, i.e., the current output by the welding power source, in amperes (A); t is the duration of the welding current, i.e., the duration of the welding power source's output current, in seconds (s); c is the amount of heat absorbed by a unit mass of the current collector 140 material to raise its temperature by 1 Kelvin, in j; ΔT is the temperature rise of the welding area (the end faces of the current collector 140 and the battery cell 120) relative to the initial temperature (room temperature or preheating temperature) during welding, in degrees Celsius (°C); and S is in mm. 2 The unit of h4 is mm. The specific derivation process is as follows:

[0070] Assuming that all electrical energy (U×I×t) input during welding is converted into heat energy in the welding area and used to raise the temperature of the material (c×ΔT), the heat generated at the first weld mark 143 is: Q=P×t=U×I×t; power P=I 2 ×R, where P is power, U is voltage, I is current, R is resistance, and t is time; temperature rise. Where c is the specific heat capacity of the 140mm manifold material, m = ρ × S × h⁴, where m is the mass of the heated material, ρ is the material density, S is the welding area, and h⁴ is the effective penetration depth; therefore (The temperature is generally not higher than 60℃).

[0071] 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.

[0072] Please see Figure 7 This utility model also provides an electronic device 1, which may include the cylindrical battery 100 described above. A working part 11 is electrically connected to the cylindrical battery 100 to obtain electrical power. 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, and the cylindrical battery 100 is disposed at the bottom of the vehicle body, providing electrical power for the vehicle's operation 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 electrical 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.

[0073] In summary, the cylindrical battery, battery pack, and electronic device of this utility model improve battery energy efficiency and power performance and enhance overall battery safety by optimizing the welding design of the stacking part and the current collector, including adjusting the welding position and number of the stacking part.

[0074] 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 solder mark and a second solder mark. The second solder mark is formed by welding the current collector to the current collection part of the electrode assembly. The first solder mark is formed by welding the current collector to the current collection part and the electrode post. The first solder mark is distributed circumferentially, and the minimum radial distance of the first solder mark from the central axis of the central hole is R. The radius of the central hole is R. hole RR hole ≥1 mm.

2. 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 distributed radially at intervals along the electrode assembly; 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; Define the radius of the first solder mark center as R. in At the welding position where the first solder mark is formed, the thickness of the tab within the stack is T, the thickness of the current collector along the axial direction of the cylindrical battery is h1, and the thickness of the terminal post along the axial direction of the cylindrical battery is h2; the first solder mark is formed at the welding position by welding the terminal post, the current collector, and the current collection portion together in one operation from the side of the terminal post away from the current collector, and the 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. M is the number of layers of the electrode lugs involved in the welding, which is a natural number, and 3≤M≤10.

3. The cylindrical battery according to claim 2, characterized in that, The current collector is located on the side of the electrode assembly near the electrode post. The electrode post is provided with an annular mounting wall that mates with the electrode post hole of the end wall and a welding wall that is connected to the end of the mounting wall near the current collector and extends radially. The inner side wall of the mounting wall along the radial direction and the side wall of the welding wall opposite to the electrode assembly form a groove with an opening. The welding wall has the welding position in the groove. The welding wall is welded to the current collector and the current collection part at the welding position to form the first weld mark. The groove width is defined as N, and the maximum radial width of the first weld mark is defined as C, where the units of N and C are both mm. The groove width N and the maximum radial width C of the first weld mark satisfy: 。 4. The cylindrical battery according to claim 2, characterized in that, At the welding position where the first solder mark is formed, the number of stacked layers of the electrode tabs in the stacked portion is D, which is a natural number, and 16≥D≥10; And / or, define the arc center angle of the first solder mark as θ, 180°≤θ<360°.

5. The cylindrical battery according to claim 1, characterized in that, The positive electrode and the negative electrode include current collectors. 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 tabs are bent and stacked towards the central axis of the cylindrical battery to form a stacked portion. The current collector is the stacked portion. The stacked portion has a stacking height h3 along the axial direction of the cylindrical battery, where h3 is 0.1 mm to 0.5 mm.

6. The cylindrical battery according to claim 5, characterized in that, At the welding position where the first solder mark is formed, the thickness h1 of the current collector along the axial direction of the cylindrical battery is 0.3 mm to 1.0 mm; the thickness h2 of the electrode along the axial direction of the cylindrical battery is h2; the penetration depth of the first solder mark is h4, wherein: The h4 satisfies: h1 + h2 ≤ h4 ≤ h1 + h2 + h3; And / or, the ratio of h4 to the sum of h1, h2, and h3 is greater than 90%; The units for h1, h2, h3, and h4 are all mm.

7. The cylindrical battery according to claim 1, characterized in that, At the welding position where the first weld mark is formed, the welding area of ​​the first weld mark is defined as S, and the penetration depth of the first weld mark is h4; wherein S satisfies: Where: U is the voltage applied across the welding electrodes during welding, in volts (V); I is the current flowing through the welding circuit during welding, in amperes (A); t is the duration of the welding current, in seconds (s); c is the amount of heat absorbed by a unit mass of manifold material to raise its temperature by 1 Kelvin, in j; ΔT is the temperature rise of the welding area relative to its initial temperature during welding, in degrees Celsius (°C); and S is in mm. 2 The unit of h4 is mm.

8. The cylindrical battery according to claim 4, characterized in that, At the welding position where the first solder mark is formed, the number of welding layers M between the collector and the inner tab of the stack portion accounts for 0.18 to 1 of the total number of inner tab layers D of the stack portion.

9. A battery pack, characterized in that, Includes the cylindrical battery as described in any one of claims 1 to 8.

10. An electronic device, characterized in that, Includes the cylindrical battery as described in any one of claims 1 to 9.

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