Positive collector plate and cylindrical lithium ion battery

Abstract

The utility model provides a positive collector plate and a cylindrical lithium ion battery. The positive collector plate comprises a first plate body and a second plate body, the second disc body comprises a plurality of first connecting parts, second connecting parts and welding parts, the second connecting parts are formed by extending the outer side ends of the first connecting parts towards the two sides in the circumferential direction, the welding parts are formed by extending the inner side edges of the second connecting parts inwards in the radial direction, and fusing grooves are formed in the first connecting parts. When the positive collector plate is welded, the positive collector plate can be easily positioned through a tool and welded through welding equipment, whether the welding position is reasonable or not can be conveniently judged through visual observation after welding is finished, the distinguishing difficulty and the workload can be reduced, and in addition, under the abnormal condition that the current of a battery is too large, the working efficiency is improved. And the first connecting part can be fused at the position of the fusing groove to achieve the effect of cutting off current, so that the positive collector plate has a fusing protection function, and the safety of the cylindrical lithium battery can be improved.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, and in particular to a positive electrode current collector and a cylindrical lithium-ion battery. Background Technology

[0002] Currently, during the assembly of 46-series cylindrical lithium-ion batteries, the positive electrode current collector needs to be welded to both the core and the terminal post at the positive electrode side to establish a path between them. However, the current positive electrode current collector is designed as a single, flat sheet with no structures on its surface for positioning or reference. This makes positioning difficult and ensures consistent welding, thus placing high demands on positioning fixtures and welding equipment. Furthermore, after welding, it is difficult for workers to visually assess the initial weld quality, such as whether the weld placement is appropriate, further increasing the process complexity and making it difficult to guarantee weld quality.

[0003] Furthermore, the cathode material system of current cylindrical batteries is mainly based on the ternary system, which has poor high-temperature stability and is prone to rapid combustion or even explosion under conditions such as battery short circuits. Although current batteries are equipped with pressure relief devices such as safety valves, they cannot disconnect the circuit in time when a short circuit occurs during battery use, and the battery still has certain safety risks. Summary of the Invention

[0004] This application provides a positive electrode current collector and a cylindrical lithium-ion battery to at least solve the technical problems of difficulty in positioning the positive electrode current collector when welding it to the core and the safety risks of the battery in existing cylindrical lithium-ion batteries.

[0005] A first aspect of this application provides a positive electrode current collector, including a first disk body located at the center and a second disk body connected to the edge of the first disk body and extending radially outward. The first disk body is used for welding to the positive electrode post of a cylindrical lithium-ion battery, and the second disk body is used for welding to the positive electrode core of a cylindrical lithium-ion battery. The second disk body includes a plurality of first connecting portions arranged circumferentially spaced along the first disk body and extending radially outward from its edge, second connecting portions extending circumferentially to both sides from the outer ends of each of the first connecting portions, and welding portions extending radially inward from the inner edge of the second connecting portions. The first connecting portions have a fusing groove on their edges along their length direction.

[0006] The positive current collector according to the embodiments of this application has at least the following beneficial effects:

[0007] First, by arranging first connecting portions at intervals along the circumference of the first disc and extending radially outward from its edge, multiple regions separated by the first connecting portions are formed in the circumferential direction. In these regions, welding portions for welding with the core of the cylindrical lithium battery are formed by extending radially inward from the inner edge of the second connecting portion. Since the boundaries of these welding regions are clear, it is easy to position them with tooling and weld them with welding equipment during welding. Furthermore, after welding, it is easy to visually observe and judge whether the welding position is reasonable, which can reduce the difficulty of identification and workload.

[0008] Secondly, a fuse groove is provided in the first connection part. The fuse groove can reduce the width of the first connection part. In the case of abnormal current, when the current passes through this part, the heat rises and reaches the melting point, causing the first connection part to melt at this position, thereby cutting off the current and reducing the risk of thermal runaway of the cell. This gives the positive current collector a fuse protection function, which can improve the safety of the cylindrical lithium battery.

[0009] In one possible implementation, the center of the first disc body is provided with a through-hole.

[0010] By setting a central hole on the first plate, for cylindrical lithium-ion batteries, in conjunction with a negative electrode current collector structure that can inject liquid on the negative electrode side, it is compatible with liquid injection on either the negative or positive electrode side. Therefore, during the liquid injection process, liquid injection can be freely selected on either the positive or negative electrode side without any structural changes to the positive electrode current collector. Manufacturers can manufacture or purchase it as a general structural component, which can effectively reduce design and manufacturing costs and facilitate internal material management in the factory.

[0011] In one possible implementation, the second connecting portion has a plurality of evenly distributed notches on the outer edge corresponding to the position of the welding portion.

[0012] By setting a notch, during liquid injection, the electrolyte that spreads along the upper surface of the second disc to its edge can flow into the core through the notch, thereby further improving the liquid injection efficiency.

[0013] In one possible implementation, the connecting portion has a first width W, and the connecting portion has a second width W1 in the area where the fuse groove is formed, with W1 / W ranging from 42% to 63%.

[0014] By setting the W1 / W range to 42% to 63%, the fusing effect of the connection 121 can be guaranteed, thereby ensuring the safety performance of the battery.

[0015] In one possible implementation, the first connecting portion has a first edge extending along the length direction for forming the fusible groove, the length of the first edge being L1, and L1 ranging from 2 to 4 mm.

[0016] By setting the L1 range to 2-4mm, it is possible to improve the yield rate and reduce costs while ensuring battery safety.

[0017] In one possible implementation, the edges on both sides of the welded portion and the inner edge of the second connecting portion define a circumferentially extending slit, the perimeter of the outer edge of the second connecting portion is L, the total arc length of the slit is L2, and the range of L2 / L is 43% to 58%.

[0018] By setting the L2 / L range to 43%–58%, it is possible to improve the liquid injection efficiency while ensuring the welding effect of the positive current collector, and also to increase the yield rate and reduce costs.

[0019] In one possible implementation, the width of the slit in the radial direction is L4, and L4 ranges from 0.4 to 1.5 mm.

[0020] By setting the L4 range to 0.4–1.5 mm, both the welding effect of the positive current collector and the core and the liquid injection efficiency can be taken into account.

[0021] In one possible implementation, the second connecting portion has a radial width W2 in the region corresponding to the slit, wherein W2 ranges from 1 to 3 mm.

[0022] By setting the W2 range to 1-3mm, both the welding effect of the positive current collector and the core and the safety of the battery can be taken into account.

[0023] In one possible implementation, the total arc length of the notch is L3, the ratio of L3 to L ranges from 4% to 9%, and the maximum depth of the notch is L5, the range of L5 is from 0.9 to 2.1 mm.

[0024] By setting the range of L3 / L to 4%–9% and the range of L5 to 0.9–2.1 mm, both the welding effect and liquid injection efficiency of the positive electrode current collector can be taken into account.

[0025] A second aspect of this application provides a cylindrical lithium-ion battery, including the positive electrode current collector as described in the first aspect embodiment, and further including a terminal post, a winding core, and a housing. The terminal post is mounted on the housing, the winding core is located inside the housing, and a first disk body in the positive electrode current collector is welded to the terminal post, and a second disk body is welded to the winding core.

[0026] The cylindrical lithium-ion battery according to the embodiments of this application has at least the following beneficial effects:

[0027] Because it has the positive current collector of the first aspect embodiment described above, the cylindrical lithium-ion battery has the characteristics of good welding quality, low cost and good safety. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of a positive current collector provided in an embodiment of this application;

[0030] Figure 2 yes Figure 1 A schematic diagram of the positive electrode current collector assembled into a cylindrical lithium-ion battery.

[0031] Figure 3 yes Figure 1 A schematic diagram of the area S1 in the positive current collector of the circuit;

[0032] Figure 4 yes Figure 1 A schematic diagram of the area S2 in the positive current collector of the circuit;

[0033] Figure 5 yes Figure 3 Schematic sectional view along the middle AA direction;

[0034] Figure 6 yes Figure 5 A partial schematic diagram at point B in the middle;

[0035] Figure 7 yes Figure 1 A top view of the positive current collector in the circuit;

[0036] Figure 8 yes Figure 7 A partial schematic diagram at point C in the middle;

[0037] Figure 9 yes Figure 7 A partial schematic diagram at point D in the middle.

[0038] Figure label:

[0039] 100-Positive current collector, 110-First plate body, 111-Center hole, 120-Second plate body, 121-Connecting part, 1211-First connecting part, 1212-Second connecting part, 122-Welding part, 130-Fusting groove, 131-First edge, 132-Second edge, 133-Third edge, 140-Slit, 150-Notch, 160-Pit, 170-Liquid outlet;

[0040] 200 - electrode post, 210 - injection port;

[0041] 300 - core, 310 - positive end, 320 - core hole;

[0042] 400 - Housing. Detailed Implementation

[0043] The embodiments of this implementation are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this implementation, and should not be construed as limiting this implementation.

[0044] In the description of this embodiment, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this embodiment.

[0045] In the description of this embodiment, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0046] In the description of this embodiment, unless otherwise explicitly limited, terms such as setting, installing, and connecting should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this embodiment in conjunction with the specific content of the technical solution.

[0047] Figure 1 This is a schematic diagram of the structure of a positive current collector 100 provided in an embodiment of this application. Figure 2 yes Figure 1 A schematic diagram of the positive electrode current collector 100 assembled into a cylindrical lithium-ion battery, as shown in the figure. Figure 1 and Figure 2 As shown, the positive current collector 100 includes two parts: a first disk body 110 and a second disk body 120. The first disk body 110 is used to connect to the electrode post 200, and the second disk body 120 is used to connect to the winding core 300, so that a passage is formed between the winding core 300 and the electrode post 200. It can be understood that, as... Figure 2 As shown, in a cylindrical lithium-ion battery, the electrode post 200 and the core 300 are located in the thickness direction of the positive electrode current collector 100. Figure 2 The two sides of the first disc 110 (in the height direction) are connected to the bottom of the pole post 200, and the lower surface of the second disc 120 is connected to the positive end 310 of the core 300.

[0048] Understandably, the core 300 of the cylindrical lithium-ion battery is manufactured using a winding process. After winding, the core 300 is cylindrical, with a circular core hole 320 formed at its center. The inner cavity of the casing 400 of the cylindrical lithium-ion battery also has a circular cross-section. To accommodate the circular cross-sectional shapes of the core 300 and casing 400, and to improve space utilization, the positive electrode current collector 100 is a thin, circular disk shape, typically made of materials such as aluminum. Furthermore, to correspond to the position of the electrode post 200 in the cylindrical lithium-ion battery, the first disk 110 is located in the central region of the positive electrode current collector 100, while the second disk 120 is located in the peripheral region of the positive electrode current collector 100. That is, viewed radially, the second disk 120 extends radially from the edge of the first disk 110. Thus, the lower surface of the second disk 120 precisely corresponds to the positive electrode 310 surrounding the core hole 320.

[0049] Furthermore, the terminal post 200 of a cylindrical lithium-ion battery is typically a cylindrical structure with a circular bottom surface. To match the circular bottom surface shape of the terminal post 200, in some embodiments, such as... Figure 1 As shown, the first disc 110 can be circular, and the second disc 120 can be circular to match the annular end face shape of the positive terminal 310. Thus, the required welding areas can be formed between the first disc 110 and the pole post 200, and between the second disc 120 and the positive terminal 310, so as to form a good welding connection between the two.

[0050] Continue to refer to Figure 1 In this embodiment of the application, a central hole 111 is provided at the center of the first disc 110, which is used for liquid injection on the positive electrode side. Combined with... Figure 2On the positive electrode side of the cylindrical lithium-ion battery, an injection hole 210 is provided on the electrode post 200, so that the injection hole 210 is aligned with and connected to the central hole 111. This allows electrolyte to be injected externally through the channel formed by the injection hole 210 and the central hole 111, thus enabling electrolyte injection on the positive electrode side. Furthermore, to match the shape of the circular core hole 320, the central hole 111 is preferably a circular hole.

[0051] It is understood that the positive current collector 100 provided in this application embodiment, by providing a central hole 111 on the first disk body 110, can be compatible with either negative-side or positive-side liquid injection for cylindrical lithium-ion batteries, in conjunction with the negative current collector structure that can be used for liquid injection on the negative side. Therefore, in the liquid injection process, liquid injection can be freely selected on either the positive or negative side without any structural changes to the positive current collector 100. Manufacturers can manufacture or purchase it as a general structural component, which can effectively reduce design and manufacturing costs and facilitate internal material management in the factory.

[0052] refer to Figure 3 and Figure 4 In this embodiment, the area of ​​the first disc body before deducting the center hole is S1, and the area of ​​the center hole 111 is S2. The ratio of S2 / S1 ranges from 4.2% to 8.6%. For example, S2 / S1 can be 4.2%, 5%, 6.8%, 8.6%, etc. In some embodiments, the area S1 of the first disc body 110 is 107.51 mm². 2 The area S2 of the central hole 111 is 7.51 mm. 2 If S2 / S1 is greater than 8.6%, the effective welding area of ​​the welding region of the first plate 110 will be reduced, thereby decreasing the current carrying capacity at the weld and causing an increase in the overcurrent temperature rise of the solder area, which in turn increases the internal resistance of the battery and reduces the overall performance of the battery. Conversely, if S2 / S1 is less than 4.2%, the electrolyte inflow time will be too long during electrolyte injection, resulting in reduced injection efficiency, which in turn reduces production efficiency and increases the manufacturing cost of the battery. By setting S2 / S1 in the range of 4.2% to 8.6%, both the welding effect of the positive electrode current collector 100 and the electrode post 200 and the injection efficiency can be balanced.

[0053] In some embodiments, the diameter of the central hole 111 is D, which ranges from 2 to 4 mm. For example, the diameter D of the central hole 111 can be 2 mm, 3 mm, or 4 mm. If D is greater than 4 mm, the effective welding area of ​​the welding region of the first plate 110 will be reduced, thereby reducing the current carrying capacity at the welding point and causing the overcurrent temperature rise in the solder area to increase, which in turn increases the internal resistance of the battery and reduces the overall performance of the battery. Conversely, if D is less than 2 mm, the electrolyte inflow time will be too long during electrolyte injection, thereby reducing the electrolyte injection efficiency, which in turn reduces the production efficiency and increases the manufacturing cost of the battery. By setting D in the range of 2 to 4 mm, both the welding effect of the positive electrode current collector 100 and the electrode post 200 and the electrolyte injection efficiency can be balanced.

[0054] In some embodiments, such as Figure 3 and Figure 4 As shown, and in combination Figure 2 Along the thickness direction of the positive current collector 100 ( Figure 2 In the height direction of the battery, the first disk 110 and the second disk 120 are staggered, meaning the first disk 110 is higher than the second disk 120. This means that a recess 160 is formed at the bottom of the positive current collector 100 corresponding to the area of ​​the first disk 110. Therefore, after the positive current collector 100 is assembled into the cylindrical lithium-ion battery, the bottom of the first disk 110 can define a chamber between itself and the positive terminal 310 of the core 300. During electrolyte injection, this chamber can temporarily store the electrolyte injected through the central hole 111. Furthermore, since the surface of the first disk 110 used for welding to the electrode post 200 is not coplanar with the upper surface of the second disk 120, its surface area is smaller. Therefore, the surface flatness of the first disk 110 can be better guaranteed, allowing it to fit well with the bottom surface of the electrode post 200, thereby improving the welding effect.

[0055] Furthermore, an outlet 170 is provided on the positive current collector 100, connecting the recess 160 to the upper surface of the second disc 120. It is understood that during electrolyte injection, the electrolyte entering the chamber can spread through the outlet 170 to the upper surface of the second disc 120, and be injected into the interior of the core 300 through through-hole structures constructed on the second disc 120, such as the slit 140 and notch 150 described below, thereby effectively improving the electrolyte injection efficiency.

[0056] Furthermore, in some embodiments, the height difference between the surface of the second disc 120 near the first disc 110 and the surface of the first disc 110 is H, where H ranges from 0.6 to 1.4 mm. For example, H can be 0.6 mm, 0.8 mm, 1.1 mm, or 1.4 mm. It should be noted that the surface of the first disc 110 described herein refers to the surface used for welding to the electrode post 200, i.e. Figure 3 and Figure 4 The upper surface of the second disk 120, and the side of the second disk 120 closest to the first disk 110, refers to the surface located on the same side as the surface used for welding to the pole post 200, i.e. Figure 3 and Figure 4 The upper surface of the battery. If H is greater than 1.4 mm, the positive current collector 100 will occupy the assembly space of the internal core 300, resulting in a decrease in battery capacity and performance. Conversely, if H is less than 0.6 mm, the height of the first disc 110 relative to the second disc 120 is too low, resulting in a small cavity space between the bottom of the first disc 110 and the positive terminal 310 of the core 300. During electrolyte injection, the electrolyte will flow from the cavity to the surface of the second disc 120 and be injected into the core 300 through the through-hole structure on the second disc 120 for too long, thus reducing the injection efficiency, leading to reduced production efficiency, increased battery manufacturing costs, and a higher risk of electrolyte overflow during injection. By setting H in the range of 0.6–1.4 mm, battery performance and injection efficiency can be balanced.

[0057] In some embodiments, such as Figure 1 , Figure 3 , Figure 4 as well as Figure 7 As shown, the second disc 120 includes a connecting portion 121 and a welding portion 122 connected together, and the welding portion 122 is connected to the edge of the first disc 110 by the connecting portion 121. It is understood that in the connecting portion 121 and the welding portion 122 constituting the second disc 120, the welding portion 122 is used to weld to the positive terminal 310 of the core 300, while the connecting portion 121 is used to connect the welding portion 122 to the first disc 110. In this embodiment, a fusing groove 130 is provided on the edge of the connecting portion 121 along its length direction. Specifically, the fusing groove 130 is a structure formed by an inward concavity along the width direction of the edge of the connecting portion 121 along its length direction. This fusing groove 130 can reduce the width of the connecting portion 121. In the event of an abnormally high current, when the current passes through this location, the heat increases and reaches the melting point, causing the connecting portion 121 to melt at that location, achieving the effect of cutting off the current, thereby reducing the risk of thermal runaway of the battery cell. It is understandable that when the second plate body 120 is provided with multiple sets of connecting parts 121 and welding parts 122, each connecting part 121 is provided with a fusible groove 130 so as to completely cut off the current flowing through the positive current collector 100 in the event of an abnormal current exceeding the limit.

[0058] Specifically, the connecting portion 121 is elongated and extends radially, with a certain width extending circumferentially. Two fuse grooves 130 are provided on each connecting portion, and these two fuse grooves 130 are symmetrically arranged on both sides of the width direction of the connecting portion 121. Furthermore, since the positive current collector 100 itself is thin, the connecting portion 121 is also thin in the thickness direction. Therefore, by providing fuse grooves 130 on both sides of its width direction, the cross-sectional area at this location can be significantly reduced, so that the connecting portion 121 can quickly fuse under abnormal conditions of excessive current.

[0059] Further, refer to Figure 8 In some embodiments, the connecting portion 121 has a first width W, and the connecting portion 121 has a second width W1 in the area where the fuse groove 130 is formed, with W1 / W ranging from 42% to 63%. For example, W1 / W can be 42%, 48%, 56%, 63%, etc. In some embodiments, the first width W is 4 mm, and the second width W1 is 2 mm. In the embodiments of this application, the second width W1 refers to the change in the width of the connecting portion 121 relative to the first width W due to the design of the fuse groove 130. Based on the definition of the second width W1 in the embodiments of this application, the first width W in this application refers to the width of the connecting portion 121 at the location other than the fuse groove 130. Further, the first width W and the second width W1 are equal in width. If W1 / W is greater than 63%, the second width W1 of the connecting portion 121 at the corresponding fuse groove 130 is too wide, and it cannot quickly fuse under abnormal conditions of excessive current, increasing the safety risk. Conversely, if W1 / W is less than 42%, the second width W1 of the connecting part 121 at the corresponding fuse groove 130 will be too small. On the one hand, this will make the fuse sensitivity too high, easily causing the battery to fail due to open circuit. On the other hand, it will also increase the internal resistance, affecting the normal use of the battery. By setting W1 / W in the range of 42% to 63%, the fuse breaking effect of the connecting part 121 can be guaranteed, thereby ensuring the safety performance of the battery.

[0060] In some embodiments, the connecting portion 121 has a first edge 131 extending along its length for forming the fuse groove 130. The length of the first edge 131 is L1, and L1 ranges from 2 to 4 mm. For example, L1 is 2 mm, 3 mm, or 4 mm. As mentioned above, the positive electrode current collector 100 is usually made of aluminum, which is relatively soft and has low strength. Therefore, if L1 is greater than 4 mm, the connecting portion 121 is more likely to deform or even break at the location of the fuse groove 130. The positive electrode current collector 100 itself is easily scrapped, resulting in waste and increasing management difficulty. In addition, if the metal shavings generated fall into the battery, there is a risk of battery short circuit. Furthermore, burrs and sharp corners at the cross-section may puncture the separator and cause battery short circuit, thereby increasing the safety risk of the battery. Conversely, if L1 is less than 2mm, heat is easily transferred to the first plate 110 and the welding part 122, which will reduce the fusing sensitivity of the fusing groove 130 and prolong the fusing time, thereby increasing the safety risk of the battery. By setting L1 in the range of 2-4mm, it is possible to improve the yield rate and reduce costs while ensuring battery safety.

[0061] It is understood that in this embodiment, both sides of the connecting portion 121 in the width direction are provided with fuse grooves 130. Therefore, the aforementioned second width W1 is the vertical distance between the first edges 131 of the two fuse grooves 130. Furthermore, as... Figure 8 As shown, in addition to the first edge 131, the bottom of the fuse groove 130 also has a second edge 132 and a third edge 133 that are respectively connected to the two ends of the first edge 131. The first edge 131, the second edge 132 and the third edge 133 together form a fuse groove 130 with a generally trapezoidal shape.

[0062] Continue to refer to Figure 1 , Figure 3 , Figure 4 as well as Figure 7In some embodiments, the second disc 120 includes a connecting portion 121 and a welding portion 122. Further, the connecting portion 121 includes a first connecting portion 1211 and a second connecting portion 1212. Multiple first connecting portions 1211 are arranged circumferentially around the first disc 110 and extend radially outward from their edges; that is, these first connecting portions 1211 are radially distributed with the center of the first disc 110 as the center. The second connecting portions 1212 are formed by extending circumferentially to both sides from the outer ends of each first connecting portion 1211. Furthermore, multiple welding portions 122 are correspondingly disposed within the area defined by two adjacent first connecting portions 1211 and second connecting portions 1212, and are formed by extending radially inward from the inner edge of the second connecting portion 1212. It is understood that the second connecting portion 1212, formed by extending circumferentially from the outer ends of each first connecting portion 1211, constitutes an annular structure surrounding the periphery of the first disk body 110, and the outer edge of this annular structure is used to define the boundary of the entire positive current collector disk 100.

[0063] It is understandable that, in order to simplify the structure, the aforementioned fuse groove 130 can be provided on the first connecting part 1211.

[0064] It is understood that in the above structure, there are multiple welding parts 122 for welding to the positive terminal 310, and their number corresponds to the number of the first connecting parts 1211. For example, if there are 3 first connecting parts 1211, there are also 3 welding parts 122. These welding parts 122 are arranged in multiple areas separated by the first connecting parts 1211 along the circumferential direction. Thus, when viewed from the top view of the positive current collector 100, it is divided into multiple welding areas, and the boundaries of these welding areas are clear. Therefore, during welding, it is easy to position the welding area using tooling and to weld it using welding equipment. After welding, it is easy to judge whether the welding position is reasonable by visual observation or visual inspection equipment, which can reduce the difficulty of identification and workload.

[0065] It can be further understood that the weld portion 122 extends inward from the inner edge of the second connecting portion 1212. In some embodiments, in order to increase the welding area of ​​each weld portion 122 (see reference...), Figure 7In the shaded area E), the edge of the welded portion 122 extends close to the edge of the first disc 110 and the edge of the first connecting portion 1211. Thus, a circumferentially extending gap exists between the welded portion 122 and the first disc 110. This gap serves as the aforementioned outlet 170, allowing the electrolyte entering the chamber to spread to the upper surface of the second disc 120 during injection. Furthermore, a radially extending gap exists between the welded portion 122 and the first connecting portions 1211 located on both sides thereon, and this gap serves as a through-hole structure for injecting electrolyte into the core 300. It is understood that in the above configuration, the gaps formed between the welded portion 122 and the first disc 110 and the first connecting portion 1211 are connected; therefore, the electrolyte can flow along the two gaps, improving injection efficiency.

[0066] Furthermore, in some embodiments, such as Figure 7 As shown, circumferentially extending slits 140 are defined on both sides of the welding portion 122 and on the inner side of the second connecting portion 1212. By defining circumferentially extending slits 140 on both sides of the welding portion 122 and on the inner side of the second connecting portion 1212, during electrolyte injection, electrolyte can be injected into the interior of the core 300 through the slits 140 at the far end away from the first disc body 110, thus improving the electrolyte injection efficiency.

[0067] In some embodiments, the circumference of the outer edge of the second connecting portion 1212 is L, the total arc length of the slit 140 is L2, and the range of L2 / L is 43% to 58%. For example, L2 / L can be 43%, 50%, 58%, etc. For example, in some embodiments, L is 133.52 mm, the number of welded portions 122 is 3, the number of slits 140 is 6, and the total arc length L2 of the 6 slits 140 is 66.78 mm. It should be noted that the circumference L referred to in the embodiments of this application refers to the circumference of the entire circle containing the outer edge of the annular structure formed by the second connecting portions 1212 extending circumferentially from the outer ends of each first connecting portion 1211, i.e. Figure 7 The circumference of the circle containing the baseline F at the 150-degree gap in the middle is given for ease of understanding. Figure 7 The outer edge of the second connecting portion 1212 is indicated by a dashed line. Furthermore, Figure 9Only a portion of L2, specifically the arc length of one section of the slit 140, is indicated. Furthermore, L2 here also includes the arc length of the gap formed between the welded portion 122 and the first connecting portion 1211, which communicates with the slit 140. If L2 / L is greater than 58%, the structural strength of the connection between the welded portion 122 and the second connecting portion 1212 is low, making it prone to deformation and affecting the welding effect. A lower yield also leads to increased costs. Conversely, if L2 / L is less than 43%, the time required for the electrolyte to be injected into the core through the slit 140 during electrolyte injection remains relatively long, and the slit 140's effect on improving injection efficiency is not significant. By setting L2 / L within the range of 43% to 58%, the injection efficiency can be improved while ensuring the welding effect of the positive electrode current collector 100, and the yield can also be increased, thereby reducing costs.

[0068] Furthermore, in some embodiments, the radial width of the slit 140 is L4, and L4 ranges from 0.4 to 1.5 mm. For example, L4 can be 0.4 mm, 0.8 mm, 1.2 mm, or 1.5 mm. If L4 is greater than 1.6 mm, the opening area of ​​the slit 140 will occupy the welding area between the welding part 122 and the core 300, resulting in a reduction in the effective welding area, a decrease in the current carrying capacity at the weld, and consequently, an increase in the temperature rise at the weld. Conversely, if L4 is less than 0.4 mm, during electrolyte injection, the electrolyte flows into the core 300 through the slit 140 at a slower rate, and the slit 140 has little effect on improving the injection efficiency. By setting the range of L4 to 0.4–1.5 mm, both the welding effect between the positive current collector 100 and the core 300 and the injection efficiency can be balanced.

[0069] Furthermore, in some embodiments, the second connecting portion 1212 has a radial width W2 in the corresponding slit 140 region, where W2 ranges from 1 to 3 mm. For example, W2 can be 1 mm, 3 mm, etc. If W2 is greater than 3 mm, the second connecting portion will excessively intrude into the central region of the positive current collector 100, reducing the effective welding area between the welding portion 122 and the core 300, resulting in reduced current carrying capacity at the weld and consequently increased temperature rise at the weld. Conversely, if W2 is less than 1 mm, the structural strength of the second connecting portion 1212 at that location is insufficient, making it prone to breakage. If the resulting metal shavings fall into the battery, there is a risk of a short circuit. Furthermore, burrs and sharp corners at the fracture surface may puncture the separator, causing a short circuit and increasing the battery's safety risk. By setting the range of W2 to 1 to 3 mm, both the welding effect between the positive current collector 100 and the core 300 and the battery's safety can be balanced.

[0070] In some embodiments, such as Figure 7As shown, the second connecting portion 1212 has a plurality of evenly distributed notches 150 on its outer edge. Specifically, for example, the notches 150 can be formed by the radial inward recess of the outer edge of the second connecting portion 1212, thereby the notches 150 are defined by the recessed edge of the second connecting portion 1212 and its reference line, wherein the reference line F can be referenced to... Figure 9 The dashed line at the notch 150 is for illustrative purposes only. It represents the shape of the second connecting portion 1212 before the notch 113 is formed on its outer edge; that is, the dashed line extends naturally along the outer edge of the second connecting portion 1212. By providing the notch 150, during electrolyte injection, the electrolyte spreading along the upper surface of the second disc 120 to its edge can flow into the core 300 through the notch 150, thereby further improving the injection efficiency.

[0071] Further, in some embodiments, the notch 150 is positioned circumferentially opposite the welded portion 122 in the second connecting portion 1212, that is, in the radial direction, the center of the notch 150 is collinear with the center of the welded portion 122, and the total arc length of the notch 150 is L3, with L3 / L ranging from 4% to 9%. For example, L3 / L can be 4%, 6%, 9%, etc. For example, in some embodiments, the number of notches 150 is 3, and the total arc length L3 of the 3 notches 150 is 9 mm. It should be noted that the arc length of the notch 150 referred to in the embodiments of this application refers to the arc length defining the reference line F forming the notch 150. Therefore, Figure 9 Only a portion of L3 is shown. If L3 / L is greater than 9%, the connection area between the second connecting part 1212 and the welding part 122 is too small, making it difficult to guarantee the flatness of the welding part 122, and consequently, the welding effect. Conversely, if L3 / L is less than 4%, during electrolyte injection, the electrolyte flows into the core 300 through the notch 150 at a slower rate, and the notch 150 has little effect on improving the injection efficiency. By setting L3 / L in the range of 4% to 9%, both the welding effect and injection efficiency of the positive electrode current collector 100 can be balanced.

[0072] Furthermore, in some embodiments, such as Figure 9As shown, the maximum depth of the notch 150 is L5, which ranges from 0.9 to 2.1 mm. For example, L5 can be 0.9 mm, 1.5 mm, or 2.1 mm. If L5 is greater than 2.1 mm, the notch 150 will occupy the welding area between the welded part 122 and the core 300, resulting in a reduction in the effective welding area and a decrease in the current carrying capacity at the weld, which in turn leads to an increase in the temperature rise at the weld. Conversely, if L5 is less than 0.9 mm, the electrolyte flows into the core 300 through the notch 150 at a slower rate during electrolyte injection, and the notch 150 has little effect on improving the electrolyte injection efficiency. By setting the range of L5 to 0.9–2.1 mm, both the welding effect of the positive current collector 100 and the electrolyte injection efficiency can be balanced.

[0073] The effects of this application will be further described below with specific embodiments and comparative examples.

[0074] Example 1:

[0075] Example 1 provides a cylindrical lithium-ion battery, which includes a positive electrode current collector 100. The positive electrode current collector 100 includes a first disk body 110 and a second disk body 120 that are offset from each other in the thickness direction. The first disk body 110 has a circular central hole 111 at its center. The second disk body 120 includes three first connecting portions 1211 that extend radially outward from the edge of the first disk body 110. Second connecting portions 1212 are formed on both sides of the outer ends of the three first connecting portions 1211 that extend circumferentially. These second connecting portions 1212 together The two parts form a ring structure. In each region formed by the three first connecting parts 1211 in pairs in the circumferential direction, the inner edge of the second connecting part 1212 extends inward to form a welding part 122. A circumferentially extending slit 140 is defined between the edges on both sides of the welding part 122 and the inner edge of the second connecting part 1212. A pair of trapezoidal welding grooves 130 are provided on the edge of each first connecting part 1211 in the length direction. A notch 150 is provided on the outer edge of the second connecting part 1212 corresponding to the position of the welding part 122.

[0076] Furthermore, the positive current collector 100 also satisfies the following parameters: the first width W of the first connecting portion 1211 = 4 mm, the second width W1 of the first connecting portion 1211 at the location where the fuse groove 130 is provided = 2 mm, and the length L1 of the first edge 131 at the bottom of the fuse groove 130 = 3 mm. From the above, it can be seen that in the positive current collector 100, W1 / W = 50%.

[0077] Comparative Example 1:

[0078] Comparative Example 1 provides a cylindrical lithium-ion battery, which includes a positive electrode current collector 100. The difference between it and Example 1 is that the fusible groove 130 is not provided.

[0079] Comparative Example 2:

[0080] Comparative Example 2 provides a cylindrical lithium-ion battery, which includes a positive electrode current collector 100, and differs from Example 1 in that it does not have a notch 150.

[0081] Comparative Example 3:

[0082] Comparative Example 3 provides a cylindrical lithium-ion battery, which includes a positive electrode current collector 100, and differs from Example 1 in that W1 / W = 36%.

[0083] Comparative Example 4:

[0084] Comparative Example 4 provides a cylindrical lithium-ion battery, which includes a positive electrode current collector 100, and differs from Example 1 in that W1 / W = 68%.

[0085] Comparative Example 5:

[0086] Comparative Example 5 provides a cylindrical lithium-ion battery, which includes a positive electrode current collector 100, and differs from Example 1 in that L1 = 1.5 mm.

[0087] Comparative Example 6:

[0088] Comparative Example 6 provides a cylindrical lithium-ion battery, which includes a positive electrode current collector 100, and differs from Example 1 in that L1 = 4.5 mm.

[0089] Table 1 below shows the time (t) required for electrolyte injection into the battery, the maximum temperature (Tmax) at the fuse groove 130, and the number of folds (C) at which the first connecting part 1211 breaks after being folded at the fuse groove 130 for the positive electrode current collector 100 fabricated in the above embodiments and comparative examples.

[0090] The test method for the time (t) required for electrolyte injection into the battery is as follows: Assemble the positive electrode current collector 100 into a cylindrical lithium-ion battery. During the electrolyte injection stage, inject 77g of electrolyte into the holding cup. Align the nozzle of the holding cup with the injection hole 210 on the electrode post 200 and press it tightly. First, draw negative pressure in the holding cup for 15s, drawing it to -90KPa. The electrolyte height can be observed to decrease from the holding cup, indicating that the electrolyte is flowing into the battery. After maintaining this for 40s, positive pressure injection is performed, and nitrogen gas is injected into the battery. The battery gradually becomes positive pressure 0.8MPa. The electrolyte in the holding cup continues to flow into the battery, and the electrolyte height in the holding cup gradually decreases. Then, adjust to negative pressure injection and maintain this. Then, adjust to positive pressure injection and maintain this. Repeat the positive and negative pressure injection cycle multiple times until the electrolyte in the holding cup has completely flowed into the battery and the electrolyte height in the holding cup is 0. Record the time t (unit: seconds) at which the electrolyte has completely flowed into the battery.

[0091] The test method for the highest temperature (Tmax) at the fuse slot 130 is as follows: During the assembly of the cylindrical lithium-ion battery, the temperature acquisition wire is inserted into the battery through the liquid injection hole 210 of the terminal 200 and attached to the first connection part 1211 to set the position of the fuse slot 130. Then, the battery is manufactured according to the normal process and finally obtained as a finished battery. After that, it is charged and discharged for 10 cycles at a rate of 2C, and the highest temperature Tmax (unit: degrees Celsius) at the three positions obtained by the temperature acquisition wire is recorded.

[0092] The test method for determining the number of folds (C) at which the first connecting part 1211 breaks after being folded at the fuse groove 130 is as follows: Use scissors to cut along the radial direction from two adjacent notches 150 to obtain a 1 / 3 piece of positive current collector 100 containing a first connecting part 1211. Fold this part of the disk along the center line of the fuse groove 130. After the two sides are completely glued together, unfold it to 180° and count it as one fold. Continue until the fold breaks, then stop folding and record the number of folds.

[0093] Table 1

[0094]

[0095] As shown in Table 1, by providing a fuse groove 130 in the first connecting part 1211, and setting W1 / W to 50% and L1 to 3mm, the electrolyte injection time t is 693 seconds, the maximum temperature Tmax at the fuse groove 130 is 73.6℃, ​​and the number of folds C that cause the first connecting part 1211 to break after being folded at the fuse groove 130 is 5. It can be seen that within the above numerical range, the electrolyte injection rate and structural strength of the positive electrode current collector 100 can be well balanced, thereby effectively improving battery safety and reducing battery production costs.

[0096] As shown in Table 1, the absence of a fuse groove 130 on the positive electrode current collector 100, in addition to lacking fuse protection, will increase the electrolyte injection time t to some extent. Furthermore, an excessively large W1 / W ratio or the absence of a notch 150 will also increase the electrolyte injection time t to some extent.

[0097] As shown in Table 1, if W1 / W is too small, the maximum temperature Tmax at the fuse groove 130 will increase significantly. Conversely, if W1 / W is too large or L1 is too short, the maximum temperature Tmax at the fuse groove 130 will be lower. It is understandable that, for the location of the fuse groove 130, if the temperature cannot rise to the fusing threshold, the first connection 1211 cannot fuse in time, thus failing to provide safety protection.

[0098] As shown in Table 1, if W1 / W is too small or L1 is too large, the number of folds C that cause the first connecting part 1211 to break after being folded at the fusion groove 130 will decrease.

[0099] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this implementation. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0100] Although embodiments of this implementation have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this implementation, the scope of which is defined by the claims and their equivalents.

Claims

1. A positive current collector plate, characterized by, The positive current collector disc (100) comprises a first disc body (110) located at the center and a second disc body (120) connected with the edge of the first disc body (110) and extending radially outward, the first disc body (110) is used for welding with the pole of a cylindrical lithium ion battery, the second disc body (120) is used for welding with the roll core of the cylindrical lithium ion battery, the second disc body (120) comprises a plurality of first connecting parts (1211) arranged at intervals along the circumference of the first disc body (110) and extending radially outward from the edge thereof, a second connecting part (1212) extending along the circumference to both sides from the outer side end of each first connecting part (1211), and a welding part (122) extending radially inward from the inner side edge of the second connecting part (1212), and the first connecting part (1211) is provided with a fuse slot (130) at the edge along the length direction thereof.

2. The positive current collector tab of claim 1, wherein The center of the first disc body (110) is provided with a through center hole (111).

3. The positive current collector of claim 2, wherein The outer side edge of the second connecting part (1212) at the position corresponding to the welding part (122) is provided with a plurality of uniformly distributed notches (150).

4. The positive current collector plate according to any one of claims 1 to 3, characterized in that, The connecting part (121) has a first width W, and the connecting part (121) has a second width W1 in the region where the fuse slot (130) is provided, and the range of W1 / W is 42%-63%.

5. The positive current collector of claim 4, wherein The first connecting part (1211) has a first edge (131) extending along the length direction for forming the fuse slot (130), and the length of the first edge (131) is L1, and the range of L1 is 2-4 mm.

6. The positive current collector tab of claim 2 or 3, wherein The edges on both sides of the welding part (122) and the inner side edge of the second connecting part (1212) define a slit (140) extending along the circumference, the circumference of the outer side edge of the second connecting part (1212) is L, the total arc length of the slit (140) is L2, and the range of L2 / L is 43%-58%.

7. The positive current collector of claim 6, wherein The width of the slit (140) in the radial direction is L4, and the range of L4 is 0.4-1.5 mm.

8. The positive current collector of claim 6, wherein The second connecting part (1212) has a width W2 in the radial direction at the region corresponding to the slit (140), and the range of W2 is 1-3 mm.

9. The positive current collector of claim 3, wherein The total arc length of the notch (150) is L3, the range of L3 / L is 4%-9%, and the maximum depth of the notch (150) is L5, and the range of L5 is 0.9-2.1 mm.

10. A cylindrical lithium-ion battery, characterized by, The positive current collector disc (100) comprises a first disc body (110) located at the center and a second disc body (120) connected with the edge of the first disc body (110) and extending radially outward, the first disc body (110) is used for welding with the pole of a cylindrical lithium ion battery, the second disc body (120) is used for welding with the roll core of the cylindrical lithium ion battery, the second disc body (120) comprises a plurality of first connecting parts (1211) arranged at intervals along the circumference of the first disc body (110) and extending radially outward from the edge thereof, a second connecting part (1212) extending along the circumference to both sides from the outer side end of each first connecting part (1211), and a welding part (122) extending radially inward from the inner side edge of the second connecting part (1212), and the first connecting part (1211) is provided with a fuse slot (130) at the edge along the length direction thereof.

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