A positive current collector and cylindrical lithium ion battery

Abstract

The application provides a positive current collector and a cylindrical lithium ion battery. The positive current collector comprises a disc body and a tail body extended from the disc body. The disc body is provided with a first hole in the middle and at least one second hole in the periphery of the first hole. At least one notch is further arranged at the outer periphery of the disc body. The area of the disc body is S1. The area of the notch formed based on the outer periphery edge line of the disc body is S2. The range of S2 / S1 is 0.5% to 2%. The area of the disc body is the area of the disc body without the first hole, the second hole and the notch. By arranging the notch on the outer periphery of the disc body and by reasonably setting the size of the notch, the exhaust efficiency can be improved, the safety of the battery can be improved, the electrolyte injection efficiency can be improved, the electrolyte injection time can be reduced, the production efficiency can be improved, and the manufacturing cost of the battery can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a positive current collecting disc and a cylindrical lithium ion battery. BACKGROUND

[0002] According to the packaging form, the lithium battery can be divided into three forms of square, cylinder and soft package. The cylindrical lithium ion battery gradually becomes a research hotspot of lithium battery because of good consistency, high production efficiency, strong heat dissipation ability on the system level and other characteristics. The cylindrical battery is usually packaged with a cylindrical steel shell, the bare cell is made by winding process to form a cylindrical winding core, and the cap is located at the top of the battery and connected with the positive electrode in the winding core through the positive current collecting disc.

[0003] In the related art, the positive current collecting disc generally includes a disc body and a tail body integrally extended from one side edge of the disc body. In the assembly process, the disc body of the positive current collecting disc needs to be welded with the positive electrode end of the winding core, and the tail body of the positive current collecting disc is welded with the cap to realize the electrical connection between the winding core and the cap. It can be understood that when the cylindrical lithium ion battery is in use, if the cell has a short circuit or other thermal runaway, a large amount of gas will be generated in the steel shell. Since the disc body is welded with the positive electrode end of the winding core, the disc body will hinder the gas from being discharged from the side of the cap, thereby increasing the safety risk of the battery. In addition, as the requirements for battery capacity and energy density become higher, the current design of the cylindrical lithium ion battery has a higher assembly ratio. The higher assembly ratio leads to a too long liquid injection time and a low liquid injection efficiency, which finally increases the battery manufacturing cost. SUMMARY

[0004] The present application provides a positive current collecting disc and a cylindrical lithium ion battery to at least solve the technical problem of low liquid injection efficiency and exhaust rate of the existing cylindrical lithium ion battery.

[0005] The first aspect of the present application provides a positive current collecting disc for a cylindrical lithium ion battery, which includes a disc body and a tail body extended from the disc body. The disc body is provided with a first hole located at the center and at least one second hole located at the outer periphery of the first hole. The disc body is further provided with at least one notch at the outer periphery. The area of the disc body is S1, the area of the notch formed with the disc body outer periphery edge line as a reference is S2, and the range of S2 / S1 is 0.5% to 2%. The area of the disc body is the area of the disc body without the first hole, the second hole and the notch.

[0006] The positive current collecting disc according to the present application has at least the following beneficial effects:

[0007] By setting the notch on the outer periphery of the disc body and by reasonably setting the size of the notch, on the one hand, in the case of short circuit or thermal runaway gas production in the battery, part of the gas is shunted through the notch, the exhaust efficiency is improved, and the safety of the battery is improved; on the other hand, in the process of liquid injection, when the electrolyte flows into the disc surface of the disc body, part of the electrolyte will flow directly into the battery through the first hole and the second hole, and part of the electrolyte will reach the outer periphery of the disc body along the disc surface of the disc body. Due to the existence of the notch, this part of the electrolyte will flow into the battery along the notch, improve the electrolyte injection efficiency, reduce the injection time, improve the production efficiency, and reduce the manufacturing cost of the battery.

[0008] In a possible implementation, the area of the second hole is S3, and the range of S3 / S1 is 6% to 13%. By setting the range of S3 / S1 to be 6% to 13%, the injection efficiency, exhaust efficiency of the positive current collecting disc can be taken into account, and at the same time, good welding effect between the positive current collecting disc and the roll core can be ensured.

[0009] In a possible implementation, the area of the first hole is S4, and the range of S4 / S1 is 4% to 12%. By setting the range of S4 / S1 to be 4% to 12%, the injection efficiency, exhaust efficiency of the positive current collecting disc can be taken into account, and at the same time, good welding effect between the positive current collecting disc and the roll core can be ensured.

[0010] In a possible implementation, the outer periphery of the disc body includes a circular arc edge, the radius of the circular arc edge is L1, the first hole and the circular arc edge share a common center, the distance between the center of the second hole and the center of the first hole is L2, and the range of L2 / L1 is 50% to 64%. By setting the range of L2 / L1 to be 50% to 64%, the structural strength of the connection part between the first hole, the second hole and the notch can be ensured, thereby improving the safety of the battery.

[0011] In a possible implementation, the notch is arranged on the circular arc edge, the distance between the deepest part of the notch and the center of the first hole is L3, and the range of L3 / L1 is 86% to 93%. By setting the range of L3 / L1 to be 86% to 93%, the injection efficiency, exhaust efficiency of the positive current collecting disc can be taken into account, and at the same time, good welding effect between the positive current collecting disc and the roll core can be ensured.

[0012] In a possible implementation, the shape of the notch is a sector, the notch forms an included angle a, and the range of the included angle a is 72° to 95°. Setting the included angle a to be 72° to 95° helps to balance the injection, exhaust efficiency and the welding strength between the disc body and the roll core.

[0013] In a possible implementation, the number of the second holes and the number of the notches are both 3, and the 3 second holes and the 3 notches are all arranged around the first hole. Corresponding the number of the notches to the number of the second holes, and both being arranged as 3, can balance the overall structural strength of the disc body and the liquid injection and exhaust efficiency.

[0014] In a possible implementation, the 3 second holes and the 3 notches are arranged one by one in correspondence, and the corresponding notch and the second hole are both collinear with the center of the first hole. Arranging the notch and the second hole to be collinear with the center of the first hole facilitates processing, and can avoid the notch occupying the welding area and reduce the influence of the notch on the welding effect.

[0015] In a possible implementation, the outer periphery of the disc body includes a circular arc edge, the first hole and the circular arc edge share the same center, the circular arc edge includes at least half a circumference, two of the 3 notches are centrally symmetrically distributed on the outer periphery of the circular arc edge, and the other notch is located between the two notches. Uniformly distributing the 3 notches on the circular arc edge can facilitate more uniform liquid injection and more rapid and uniform exhaust.

[0016] The second aspect of the embodiments of the present application provides a cylindrical lithium ion battery, which includes any one of the positive electrode current collecting disc, the winding core, the negative electrode current collecting disc, the cap and the shell provided in the above embodiments. The disc body of the positive electrode current collecting disc is connected with the winding core, and the tail body of the positive electrode current collecting disc is connected with the cap.

[0017] The cylindrical lithium ion battery according to the embodiments of the present application has at least the following beneficial effects:

[0018] The cylindrical lithium ion battery of the embodiments of the present application is provided with notches on the outer periphery of the positive electrode current collecting disc, which helps to improve the internal exhaust rate and the liquid injection efficiency of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the description of the embodiments of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative labor.

[0020] Figure 1 is a decomposition schematic view of a cylindrical lithium ion battery provided by the embodiments of the present application;

[0021] Figure 2 is a structural schematic view of a positive electrode current collecting disc provided by the embodiments of the present application;

[0022] Figure 3 is a schematic view of an area S1 in the positive current collector plate provided by an embodiment of the present application;

[0023] Figure 4 is a schematic view of an area S2 in the positive current collector plate provided by an embodiment of the present application;

[0024] Figure 5 is a schematic view of an area S3 in the positive current collector plate provided by an embodiment of the present application;

[0025] Figure 6 is a schematic view of an area S4 in the positive current collector plate provided by an embodiment of the present application;

[0026] Figure 7 is a schematic view of the structure of the positive current collector plate provided by an embodiment of the present application;

[0027] Figure 8 is Figure 2 a partial schematic view at A in the positive current collector plate.

[0028] Reference signs:

[0029] 100 - positive current collector plate, 110 - plate body, 111 - first hole, 112 - second hole, 113 - notch, 1131 - seventh side, 1132 - eighth side, 114 - circular arc edge, 115 - first side, 116 - second side, 117 - third side, 120 - tail body, 121 - fifth side, 122 - sixth side, 123 - fourth side;

[0030] 200 - roll core, 210 - positive electrode end, 220 - negative electrode end;

[0031] 300 - negative current collector plate;

[0032] 400 - cap;

[0033] 500 - shell. DETAILED DESCRIPTION

[0034] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary only, and are for the purpose of explanation of the present application, and should not be understood as a limitation of the present application.

[0035] In the description of the embodiments, it should be understood that the orientation description, such as the orientation or position relationship indicated by up, down, front, back, left, right and the like, is based on the orientation or position relationship shown in the drawings, and is only for the purpose of facilitating the description of the embodiments and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the embodiments.

[0036] In the description of the embodiments, one or more is meant to be one or more, more than two is meant to be two or more, greater than, less than, more than and the like are understood to not include the number itself, above, below, within and the like are understood to include the number itself. If the first, second is described, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of technical features indicated.

[0037] In the description of the embodiments, unless otherwise explicitly limited, the words such as setting, installing, connecting and the like should be broadly understood, and those skilled in the art can reasonably determine the specific meaning of the above words in the embodiments in combination with the specific content of the technical solutions.

[0038] The cylindrical lithium ion battery provided by the embodiments of the present application includes various size series, such as 21 series (cylindrical lithium ion battery with an outer diameter of 21 mm), 46 series (cylindrical lithium ion battery with an outer diameter of 46 mm), which are not limited here. Specifically, as shown in Figure 1 The cylindrical lithium ion battery includes a positive current collector 100, a winding core 200, a negative current collector 300, a cap 400 and a shell 500. The positive end 210 of the winding core 200 is connected to the cap 400 through the positive current collector 100, and the negative end 220 of the winding core 200 is connected to the shell 500 through the negative current collector 300, so that the cap 400 serves as the positive electrode of the cylindrical lithium ion battery, and the shell 500 serves as the negative electrode of the cylindrical lithium ion battery, and is used for electrical connection with external electrical equipment.

[0039] As shown in Figure 2 The positive current collector 100 includes a disc body 110 and a tail body 120 connected to each other. The disc body 110 is used to connect with the positive end 141 of the winding core 200, and the tail body 120 is used to connect with the cap 400, so as to form a passage between the winding core 200 and the cap 400. In the present application, the connection between the disc body 110 and the winding core 200, and the connection between the tail body 120 and the cap 400 can adopt any connection mode known to those skilled in the art, such as welding; the connection between the tail body 120 and the disc body 110 can be any fixed connection mode, and in order to ensure stable connection and structural strength, it is preferred to be integrally connected.

[0040] To match the circular cross-section of the core 200 and facilitate welding between the disc body 110 and the core 200, the disc body 110 is a closed axisymmetric figure composed of a first side 115, an arc edge 114, a second side 116, and a third side 117 connected end to end. The tail body 120 includes a fifth side 121 and a sixth side 122 along its length, and a fourth side 123 away from the disc body 110. The two ends of the fifth side 121 are connected to the fourth side 123 and the first side 115, respectively, and the two ends of the sixth side 122 are connected to the fourth side 123 and the second side 116, respectively. Thus, from... Figure 2 As can be seen, the tail body 120 also presents a closed axisymmetric shape extending from one end of the disc body 110. It should be noted that the third side 117 is a virtual edge proposed for the convenience of describing the disc body 110; this edge does not exist in the actual product. Figure 2 Dashed lines are used for labeling to distinguish them. In addition, combined with... Figure 1 It is also understandable that when the positive current collector is assembled into the cylindrical lithium-ion battery, the tail body 120 will bend near the third side 117, and its far end will be located above the closed axisymmetric figure formed by the disk body 110.

[0041] As mentioned earlier, the disc 110 is a closed axisymmetric figure formed by connecting the first side 115, the arc edge 114, the second side 116, and the third side 117 end to end. Therefore, the disc 110 is not a complete circle when viewed as a whole. However, considering the arc edge 114, the disc 110 can be considered a circular component, and the diameter of the arc edge 114 is the diameter of the disc 110. In this case, the diameter of the disc 110 is the longest line segment between two points on the arc edge 114. Depending on the actual needs, the diameter of the disc 110 is, for example, 15-23 mm. Within the preferred diameter range, the disc 110 ensures a large contact area between the disc 110 and the core 200, increasing the weldable area and expanding the adaptability range of the weld wire length and shape.

[0042] In this embodiment, a first hole 111 is provided at the center of the disk body 110, and at least one second hole 112 is provided around the first hole 111. The first hole 111 is used to inject electrolyte into the battery, and the second hole 112 is used to assist electrolyte wetting. It should be noted that the center of the disk body 110 can be the center of the circle corresponding to the arc edge 114.

[0043] It can be understood that the winding core 200 is made by a winding process, and the center of the winding core 200 forms a circular winding core hole after winding. In order to match the shape of the winding core hole, the shape of the first hole 111 is preferably circular, and the second hole 112 can also be a circular hole. It can be understood that the diameters of the first hole 111 and the second hole 112 can be specifically selected according to the balance of the liquid injection efficiency and the weldable area.

[0044] Further, the disc body 110 is further provided with a notch 113 at the outer periphery. From Figure 2 the notch 113 is a structure formed by inwardly recessing the disc body 110 at the outer periphery of the disc body 110 towards the center of the disc body, for example, the notch 113 can be formed by mechanical cutting, laser cutting and various ways to remove material at the outer periphery of the disc body 110.

[0045] It can be understood that at least one notch 113 is required to facilitate auxiliary exhaust and auxiliary liquid injection at the outer periphery of the disc body 110. Of course, in order to further improve the exhaust efficiency and the liquid injection efficiency, the notch 113 can be provided with multiple notches 113, and the multiple notches 113 are uniformly distributed on the outer periphery of the disc body 110, for example, the notch 113 can be provided with three notches 113.

[0046] Through the foregoing manner, various shapes of notches 113 can be formed at the outer periphery of the disc body 110, for example, the notch 113 is a fan shape, as Figure 8 shown, in this case, the notch 113 is defined by the seventh edge 1131, the eighth edge 1132 and the reference line of the outer periphery of the disc body 110, wherein the reference line can refer to the dotted line at the notch 113 in Figure 3 and Figure 4 , the dotted line is for illustration, and the dotted line represents the shape of the disc body 110 when the disc body 110 is not cut with the notch 113, and the dotted line is obtained by extending the outer periphery of the disc body 110 according to the original outer periphery. Of course, it is not limited to this, for example, the notch 113 can be rectangular, arc-shaped, waist-shaped, etc.

[0047] By setting the notch 113 on the outer periphery of the disc body 110, on the one hand, in the case of short circuit or thermal runaway gas production in the battery, part of the gas can be shunted through the notch 113, improving the exhaust efficiency and improving the safety of the battery. On the other hand, during the liquid injection process, when the electrolyte flows into the disc surface of the disc body 110, part of the electrolyte will flow directly into the battery through the first hole 111 and the second hole 112, and part of the electrolyte will reach the outer periphery of the disc body 110 along the disc surface of the disc body 110. Due to the presence of the notch 113, this part of the electrolyte will flow into the battery along the notch 113, improving the electrolyte injection efficiency, reducing the injection time, improving the production efficiency, and reducing the manufacturing cost of the battery. It can be understood that the art usually adopts the method of opening holes in the interior of the disc body 110 to improve the injection efficiency, and in the design process, the weldable area of the disc body itself also needs to be balanced in order to facilitate welding with the winding core 200 and design of welding tool clamps. The present application assists in exhaust and injection by opening a notch 113 on the outer periphery, which minimizes the adverse effects on the disc body 110. For example, by reasonably designing the size and shape of the notch 113, the influence on the welding of the disc body 110 can be effectively avoided.

[0048] As shown in Figure 3 and Figure 4 , in some embodiments, the area of the disc body 110 is S1, the area of the notch 113 is S2, and the range of S2 / S1 is 0.5% to 2%, i.e. 0.5%≤S2 / S1≤2%. For example, S1 is 229.14mm 2 , S2 is 2.94mm 2 , and S2 / S1 is 1.3%. Among them, the area S1 of the disc body 110 refers to the area of the disc surface of the disc body 110, i.e. the area of the disc body 110 without the first hole 111, the second hole 112 and the notch 113 and the like. For example, as shown in the figure, S1 is the area of the closed figure formed by the circular arc edge 114 and the third edge 117. The area S2 of the notch 113 refers to the total area of all notches 113 on the disc body 110. It can be further understood that only for a single notch 114, the area refers to the area of the region defined by the reference line of the outer periphery edge of the disc body 110 and the boundary line of the notch 113 itself. For example, the area S2 of the aforementioned sector-shaped notch 113 is the area of the sector-shaped region formed by the seventh edge 1131, the eighth edge 1132 and the reference line of the outer periphery of the disc body 110.

[0049] Understandably, if the area S2 of the notch 113 is too small, on the one hand, the notch 113 will not significantly improve the electrolyte injection efficiency during the electrolyte injection process, and there will be a risk of electrolyte overflow, which could lead to problems such as electrolyte contamination of the casing, rusting, or even battery failure. Furthermore, it would require additional manpower to handle the overflow, increasing manufacturing costs. On the other hand, if a short circuit or other thermal runaway occurs during battery use, the gas generated inside the battery cannot be discharged in time through the notch 113, limiting its effectiveness in improving battery safety. Conversely, if the area S2 of the notch 113 is too large, the notch 113 will occupy the welding area on the surface of the disc 110, reducing the welding area between the disc 110 and the positive terminal 210 of the core 200. This would result in insufficient current-carrying capacity at the welding position, leading to excessive overcurrent temperature rise and subsequent thermal control safety issues, thus reducing the battery's safety performance. By setting the range of S2 / S1 to 0.5% to 2%, it is possible to ensure a good welding effect between the disc body 110 and the core 200 while taking into account the liquid injection efficiency and venting efficiency of the disc body 110.

[0050] Furthermore, such as Figure 3 and Figure 5 As shown, in some embodiments, the area of ​​the second hole 112 is S3, and the ratio of S3 to S1 ranges from 6% to 13%, i.e., 6% ≤ S3 / S1 ≤ 13%. For example, the area of ​​the second hole 112 is 21.21 mm². 2 S1 is 229.14mm. 2 The ratio of S3 to S1 is 9.26%. Here, S3 refers to the total area of ​​all the second holes 112 on the disk body 110. For example, if there are three second holes 112, the sum of the areas of the three second holes 112 is 21.21 mm². 2 .

[0051] Understandably, if the area S3 of the second hole 112 is too small, on the one hand, the increased injection time during the electrolyte injection process will lead to a decrease in injection efficiency and a risk of electrolyte overflow, resulting in problems such as electrolyte contamination of the casing, rusting, and even battery failure. Furthermore, increased manpower is required to handle the overflow, increasing manufacturing costs. On the other hand, if a short circuit or other thermal runaway occurs during battery use, the gas generated inside the battery cannot be discharged in time through the second hole 112, limiting its effectiveness in improving battery safety. Conversely, if the area S3 of the second hole 112 is too large, it will occupy the welding area on the surface of the disc 110, reducing the welding area between the disc 110 and the positive terminal 210 of the core 200. This will result in insufficient current-carrying capacity at the welding position, leading to excessive overcurrent temperature rise and subsequent thermal control safety issues, thus reducing the battery's safety performance. By setting the range of S3 / S1 to 6% to 13%, it is possible to ensure a good welding effect between the disc body 110 and the core 200 while taking into account the liquid injection efficiency and venting efficiency of the disc body 110.

[0052] Furthermore, such as Figure 3 and Figure 6 As shown, in some embodiments, the area of ​​the first hole 111 is S4, and the ratio of S4 to S1 ranges from 4% to 12%, i.e., 4% ≤ S4 / S1 ≤ 12%. For example, the area of ​​the first hole 111 is 19.63 mm². 2 S1 is 229.14mm. 2 S4 / S1 is 8.6%. Among them, the first hole 111 is located at the center of the disk body 110, and there is only one of them. Therefore, the area S4 of the first hole 111 here refers only to the area of ​​the first hole 111 itself.

[0053] Understandably, if the area S4 of the first hole 111 is too small, on the one hand, during the electrolyte injection process, the narrow injection channel makes it difficult for the electrolyte to be injected into the battery, increasing the injection time and leading to a decrease in injection efficiency; on the other hand, if a short circuit or other thermal runaway occurs during battery use, the gas generated inside the battery cannot be discharged in time through the first hole 111, reducing battery safety. Conversely, if the area S4 of the first hole 111 is too large, the first hole 111 will occupy the welding area on the surface of the disc 110, reducing the welding area between the disc 110 and the positive terminal 210 of the core 200. The current-carrying capacity at the welding position will not meet the requirements, resulting in excessive overcurrent temperature rise and subsequent thermal control and other safety issues, thus reducing the battery's safety performance. By setting the range of S4 / S1 to 4%–12%, it is possible to balance the electrolyte injection efficiency and venting efficiency of the disc 110 while ensuring a good welding effect between the disc 110 and the core 200.

[0054] As mentioned earlier, the outer periphery of the disk body 110 includes an arc-shaped edge 114, such as Figure 7 As shown, in some embodiments, the first hole 111 and the arc edge 114 are co-centered, with the radius of the arc edge 114 as L1, and the distance from the center of the second hole 112 to the center of the first hole 111 as L2. The ratio of L2 / L1 is in the range of 50% to 64%, that is, 50% ≤ L2 / L1 ≤ 64%. For example, L1 is 9.1 mm, L2 is 5.13 mm, and L2 / L1 is 56.37%.

[0055] It is understandable that the dimensions of a cylindrical lithium-ion battery are basically fixed, that is, the diameter of the casing of a cylindrical lithium-ion battery is determined. Therefore, the diameter of the disk body 110 of the positive electrode current collector 100 assembled into the casing is basically determined. Since the first hole 111 is located in the center of the disk body 110, if L2 / L1 is too large, the second hole 112 and the notch 113 will be too close. In this case, the structural strength of the connection between the second hole 112 and the notch 113 may be insufficient, and there is a risk of breakage. Moreover, once this part breaks, metal shavings will be generated, and the burrs generated at the fracture point can also easily deform inward and puncture the separator. Both metal shavings and burrs may cause short circuit failure of the battery, which poses a safety risk. Conversely, if L2 / L1 is too small, the second hole 112 will be too close to the first hole 111. This could result in insufficient structural strength at the connection between the second hole 112 and the first hole 111, posing a risk of breakage. Furthermore, if this part breaks, it will generate metal shavings, and the burrs at the fracture point can easily deform inwards and puncture the separator. Both the metal shavings and the burrs could cause a short circuit in the battery, posing a safety risk. By setting the L2 / L1 range to 50%–64%, the structural strength of the connection between the first hole 111, the second hole 112, and the notch 113 can be ensured, thereby improving battery safety.

[0056] As mentioned earlier, the disc body 110 is a closed axisymmetric shape formed by the first side 115, the arc edge 114, the second side 116, and the third side 117 connected end to end. In order to enable the notch 113 to play a better role in assisting venting and liquid injection, in some embodiments, the notch 113 is set at the outer periphery of the arc edge 114. At the same time, the distance from the deepest point of the notch 113 to the center of the first hole 111 is L3, and the range of L3 / L1 is 86% to 93%, that is, 86% ≤ L3 / L1 ≤ 93%. For example, L1 is 9.1 mm, L3 is 8.11 mm, and L3 / L1 is 89.12%. It should be noted that the deepest point of the notch 113 refers to the position where the edge forming the notch 113 is closest to the center of the arc edge 114. Taking the aforementioned fan-shaped notch 113 as an example, the deepest point of the notch 113 is the intersection of the seventh side 1131 and the eighth side 1132.

[0057] Understandably, if L3 / L1 is too small, the depth of the notch 113 will be deeper, resulting in a larger area of ​​the notch 113 (taking a fan-shaped notch 113 as an example, assuming the angle α between the seventh side 1131 and the eighth side 1132 remains unchanged). In this case, the notch 113 will occupy the welding area on the disk surface of the disk body 110, resulting in a reduction in the welding area between the disk body 110 and the positive terminal 210 of the core 200. The overcurrent capacity at the welding position will not meet the requirements, thus causing excessive overcurrent temperature rise and triggering subsequent safety issues such as thermal control, leading to a decrease in the safety performance of the battery. Conversely, if L3 / L1 is too large, the depth of notch 113 will be shallow, resulting in a smaller area. On one hand, during electrolyte injection, notch 113 will not significantly improve injection efficiency and may pose a risk of electrolyte overflow, leading to problems such as electrolyte contamination of the casing, rusting, and even battery failure. Furthermore, it requires additional manpower to handle overflow issues, increasing manufacturing costs. On the other hand, if a short circuit or other thermal runaway occurs during battery use, the gas generated inside the battery cannot be promptly discharged through notch 113, limiting its effectiveness in improving battery safety. By setting L3 / L1 within the range of 86% to 93%, both the injection and venting efficiency of the disc 110 can be considered, while ensuring good welding between the disc 110 and the core 200.

[0058] In some implementations, such as Figure 2 and Figure 8 As shown, the notch 113 is fan-shaped, forming an included angle α, which ranges from 72° to 95°, i.e., 72°≤α≤95°. If the included angle α is too small, the electrolyte will have difficulty passing through during injection, resulting in a smaller injection flow rate, longer injection time, and decreased production efficiency. If the included angle α is too large, it will affect the positioning and clamping of the welding fixture during subsequent welding of the disc 110 to the positive terminal 210 of the core 200. The welding fixture will need to occupy other disc surfaces, reducing the welding area, decreasing the welding current capacity, and increasing the temperature rise at the weld, thus affecting the overall battery performance. In some embodiments, the fan-shaped notch 113 is symmetrical about the radius of the arc edge 114. Setting α to 72° to 95° helps to balance the injection and venting efficiency and the welding strength between the disc 110 and the core 200.

[0059] In some embodiments, there are three notches 113 and three second holes 112. The three second holes 112 are arranged around the first hole 111, and the positions of the second holes 112 correspond to the notches 113. The first hole 111 is located at the center of the arc edge 114. Corresponding the number of notches 113 and the number of second holes 112, and setting them to three in each case, is beneficial to balancing the overall structural strength of the disc body 110 and the efficiency of liquid injection and venting.

[0060] Further, in some embodiments, the centers of the first hole 111, the second hole 112 and the notch 113 are collinear. In the process of cutting the second hole 112 and the notch 113, the positive current collector needs to be placed on the mold for positioning, and the positions of the second hole 112 and the notch 113 correspond to each other, which is beneficial to realize positioning and cutting. At the same time, if the notch 113 is not collinear with the second hole 112 and the notch 113, the notch 113 will occupy the welding area, resulting in a decrease in the welding area and affecting the welding effect.

[0061] Further, in some embodiments, the circular arc edge 114 includes at least half a circumference, and two of the three notches 113 are symmetrically distributed with the center of the circle as the center, and the other notch 113 is the same distance from the two notches 113. Uniformly distributing the three notches 113 on the circular arc edge 114 is beneficial to make the liquid injection effect more uniform, and is also beneficial to exhaust more quickly and uniformly.

[0062] The following further describes the effects of the present application with specific examples and comparative examples.

[0063] It should be noted that the following examples and comparative examples of the present application are based on the common 2170 cylindrical lithium ion battery design and production in the art, and therefore, in addition to the production of the positive current collector according to the foregoing structure, other components and materials can be obtained by referring to the 2170 cylindrical lithium ion battery. For example, the positive plate, the negative plate and the electrolyte can be obtained by referring to the following preparation methods:

[0064] Preparation of the positive plate: take lithium nickel cobalt manganese oxide, carbon nanotube conductive agent, conductive carbon black and polyvinylidene fluoride (PVDF) binder as the solid substances of the positive slurry, disperse the solid substances in N-methyl-2-pyrrolidone, mix uniformly in a homogenizer, coat the slurry on both sides of the aluminum foil, and dry to obtain the positive plate.

[0065] Preparation of the negative plate: take the negative active material, acetylene black conductive agent, thickening agent (hydroxymethyl cellulose) and polyacrylate binder as the solid substances of the negative slurry, disperse the solid substances in deionized water, mix uniformly in a homogenizer, coat the slurry on both sides of the copper foil, and dry to obtain the negative plate.

[0066] Preparation of the electrolyte: mix ethylene carbonate, methyl ethyl carbonate and diethyl carbonate to obtain an organic solvent, then dissolve the fully dried lithium salt LiPF6 in the mixed organic solvent to prepare the electrolyte.

[0067] The member and the material obtained by the foregoing method can be assembled according to the known technology in the art to obtain the experimental cylindrical lithium ion battery. For example, after the positive electrode sheet and the negative electrode sheet are respectively roll-pressed, slitted, and die-cut, the positive electrode sheet, the negative electrode sheet, and the separator are simultaneously wound to form a roll core 200. The roll core 200 is cut and folded at both ends to form positive and negative electrode tabs. Then, the positive current collector 100 and the negative current collector 300 are respectively welded to the roll core 200. The negative current collector 300 is welded to the shell 500. The positive current collector 100 is placed on the insulating sheet, and the positive current collector 100 is welded to the cap 400. The experimental cylindrical lithium ion battery is obtained by completing the liquid injection, sealing, and formation processes.

[0068] Example 1:

[0069] Example 1 provides a cylindrical lithium ion battery, which includes a positive current collector 100. The positive current collector 100 includes a disc body 110 and a tail body 120 extending from the disc body 110. The disc body 110 of the positive current collector 100 faces the roll core 200, and the bent tail body 120 faces away from the roll core 200 and faces the cap 400 for electrical connection with the cap 400. The disc body 110 includes a circular arc edge 114, a first hole 111 located at the center of the circular arc edge 114, and three second holes 112 located at the outer periphery of the first hole 111. Three notches 113 in the shape of a sector are arranged at the outer periphery of the circular arc edge 114. The centers of each first hole 111, second hole 112, and notch 113 are collinear. The positive current collector 100 also satisfies the following parameters:

[0070] The area S1 of the disc body 110 is 229.14 mm 2 ; the area S2 of the notch 113 is 2.94 mm 2 ; the area S4 of the first hole 111 is 19.63 mm 2 ; the area S3 of the second hole 112 is 21.21 mm 2 ; the diameter L1 of the circular arc edge 114 is 9.1 mm; the distance L2 from the center of the first hole 111 to the center of the second hole 112 is 5.13 mm; the distance L3 from the deepest part of the notch 113 to the center of the first hole 111 is 8.11 mm; and the included angle a of the notch 113 is 80°.

[0071] As can be seen from the above, in the positive current collector, S2 / S1 = 1.3%; S3 / S1 = 9.26%; S4 / S1 = 8.6%; L2 / L1 = 56.37%; and L3 / L1 = 89.12%.

[0072] Comparative Example 1:

[0073] Comparative Example 1 provides a cylindrical lithium-ion battery including a positive current collector 100, which differs from Example 1 in that S2 / S1 = 0.2%.

[0074] Comparative Example 2:

[0075] Comparative Example 2 provides a cylindrical lithium-ion battery including a positive current collector 100, which differs from Example 1 in that S2 / S1 = 4%.

[0076] Comparative Example 3:

[0077] Comparative Example 3 provides a cylindrical lithium-ion battery including a positive current collector 100, which differs from Example 1 in that S3 / S1 = 3%.

[0078] Comparative Example 4:

[0079] Comparative Example 4 provides a cylindrical lithium-ion battery including a positive current collector 100, which differs from Example 1 in that S3 / S1 = 18%.

[0080] Comparative Example 5:

[0081] Comparative Example 5 provides a cylindrical lithium-ion battery including a positive current collector 100, which differs from Example 1 in that S4 / S1 = 2%.

[0082] Comparative Example 6:

[0083] Comparative Example 6 provides a cylindrical lithium-ion battery including a positive current collector 100, which differs from Example 1 in that S4 / S1 = 16%.

[0084] Comparative Example 7:

[0085] Comparative Example 7 provides a cylindrical lithium-ion battery including a positive current collector 100, which differs from Example 1 in that L2 / L1 = 40%.

[0086] Comparative Example 8:

[0087] Comparative Example 8 provides a cylindrical lithium-ion battery including a positive current collector 100, which differs from Example 1 in that L2 / L1 = 70%.

[0088] Comparative Example 9:

[0089] Comparative Example 9 provides a cylindrical lithium-ion battery including a positive current collector 100, which differs from Example 1 in that L3 / L1 = 83.3%, and a = 34°.

[0090] Comparative Example 10:

[0091] Comparative Example 10 provides a cylindrical lithium ion battery including a positive electrode current collector 100, which is different from Example 1 in that L3 / L1 = 96%, and a is 170°.

[0092] Comparative Example 11:

[0093] Comparative Example 11 provides a cylindrical lithium ion battery including a positive electrode current collector 100, which is different from Example 1 in that each of the first hole 111, the second hole 112, and the notch 113 are not collinear, and the angle between the line connecting the center of the first hole 111 and the center of the second hole 112 and the line connecting the center of the first hole 111 and the center of the notch 113 is 30°.

[0094] The following Table 1 evaluates the structural strength effect, the liquid injection rate, and the welding effect of the positive electrode current collector 100 produced in the above examples and comparative examples. Among them:

[0095] The specific test method for the structural strength effect is as follows: take the positive electrode current collector 100, cut the connecting part of the disc body 110 and the tail body 120 with scissors, remove the tail body 120, fold and unfold the disc body 110 along the Y-axis direction twice until the connecting part of the notch 113 to the first hole 111 is completely broken, and then stop, and record the number of folding times.

[0096] The specific test method for the liquid injection rate is as follows: assemble the positive electrode current collector 100 produced in the above examples and comparative examples into experimental cylindrical lithium ion batteries, and according to the sample preparation process, proceed to the liquid injection stage, draw negative pressure of each experimental cylindrical lithium ion battery to -90 kPa, and then start liquid injection. Inject 6.5 g of electrolyte into the liquid holding cup, and perform the first liquid injection. The electrolyte in the liquid holding cup is pressed into the battery port space by the pressure rod at a displacement speed of 0.5 mm / s, and the electrolyte at the battery port flows slowly into the battery interior through the positive electrode current collector 100. The pressure rod continues to press down, and the electrolyte continues to be injected into the battery interior through the positive electrode current collector 100. Record the time from the start of liquid injection by the pressure rod to the start of overflow of each example and comparative example, and record it.

[0097] The specific test method for the welding effect is as follows: assemble the positive electrode current collector 100 produced in the above examples and comparative examples into experimental cylindrical lithium ion batteries, drill a through hole with a diameter of 3 mm on the cap 400 of the experimental cylindrical lithium ion battery, pass the temperature control wire through the through hole, and paste it on the welding mark of the welding between the positive electrode current collector 100 and the positive electrode end 210 of the winding core 200. After liquid injection according to the normal sample preparation process, seal the cap 400, and perform formation and capacity test to produce qualified cylindrical lithium ion batteries. Perform 10 cycles of charge and discharge at 2C high rate. After 10 cycles of charge and discharge, obtain the temperature data of the welding area collected by the temperature control wire, take the maximum value Tmax in the temperature fluctuation range in 10 cycles, and record it.

[0098] Table 1

[0099]

[0100]

[0101] As can be seen from Table 1, if S2 / S1 is too large, the structural strength of the positive current collector plate 100 will be reduced, and the welding effect of the positive current collector plate 100 will also be affected, thereby causing the temperature rise of the welding area to be too high, but the liquid overflow time can be increased; on the contrary, if S2 / S1 is too small, although the structural strength of the positive current collector plate 100 and the temperature rise of the welding area can be ensured within a reasonable range, the liquid injection efficiency will be reduced, thereby the liquid overflow phenomenon occurs faster, therefore, setting S2 / S1 within a reasonable range can balance the structural strength of the positive current collector plate 100, the liquid injection rate and the welding effect.

[0102] As can be seen from Table 1, if S3 / S1 is too large, the structural strength of the positive current collector plate 100 will also be reduced, and the welding effect of the positive current collector plate 100 will also be affected, thereby causing the temperature rise of the welding area to be too high; on the contrary, if S3 / S1 is too small, although the structural strength of the positive current collector plate 100 and the temperature rise of the welding area can be ensured within a reasonable range, the liquid injection efficiency will be reduced, thereby the liquid overflow phenomenon occurs faster, therefore, setting S3 / S1 within a reasonable range can balance the structural strength of the positive current collector plate 100, the liquid injection rate and the welding effect.

[0103] As can be seen from Table 1, if S4 / S1 is too large, the structural strength of the positive current collector plate 100 will also be reduced, and the welding effect of the positive current collector plate 100 will also be affected, thereby causing the temperature rise of the welding area to be too high, but the liquid injection time can be shortened, thereby improving the liquid injection efficiency and reducing the risk of liquid overflow; on the contrary, if S4 / S1 is too small, while the structural strength of the positive current collector plate 100 and the temperature rise of the welding area can be ensured within a reasonable range, the risk of liquid overflow is increased, so that the electrolyte overflow problem occurs in a shorter time; therefore, setting S4 / S1 within a reasonable range can balance the structural strength of the positive current collector plate 100, the liquid injection rate and the welding effect.

[0104] As can be seen from Table 1, if L2 / L1 is too large or too small, the structural strength of the positive current collector plate 100 will be affected, and setting L2 / L1 within a reasonable range can ensure the structural strength of the positive current collector plate 100.

[0105] As shown in Table 1, if L3 / L1 is too small or the included angle a is too small, the structural strength of the positive current collector plate 100 is reduced; on the contrary, if L3 / L1 is too large or the included angle a is too large, although the structural strength of the positive current collector plate 100 can be ensured, the temperature rise of the welding area is too high, therefore, setting L3 / L1 and the included angle a in a reasonable range can ensure the structural strength of the positive current collector plate 100, the liquid injection efficiency and the welding effect.

[0106] As shown in Table 1, if the first hole 111, the second hole 112 and the notch 113 are not collinear, the welding effect of the positive current collector plate 100 is affected, thereby causing the temperature rise of the welding area to be too high.

[0107] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present embodiment. In the present specification, the exemplary description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0108] Although the embodiments of the present embodiment have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the present embodiment, and the scope of the present embodiment is defined by the claims and their equivalents.

Claims

1. A positive current collector for a cylindrical lithium-ion battery, characterized by, The positive electrode current collector disc (100) comprises a disc body (110) and a tail body (120) extending from the disc body (110), the disc body (110) is provided with a first hole (111) at the middle part and at least one second hole (112) at the outer periphery of the first hole (111), and the disc body (110) is further provided with at least one notch (113) at the outer periphery edge, the area of the disc body (110) is S1, the area of the notch (113) formed based on the outer periphery edge of the disc body (110) is S2, the range of S2 / S1 is 0.5%-2%, the area of the second hole (112) is S3, the range of S3 / S1 is 6%-13%, and the area of the first hole (111) is S4, the range of S4 / S1 is 4%-12%, wherein the area of the disc body (110) is the area of the disc body (110) without the first hole (111), the second hole (112) and the notch (113), the outer periphery of the disc body (110) comprises a circular arc edge (114), the radius of the circular arc edge (114) is L1, the first hole (111) and the circular arc edge (114) share the same center, the distance between the center of the second hole (112) and the center of the first hole (111) is L2, and the range of L2 / L1 is 50%-64%.

2. The positive current collector tab of claim 1, wherein The notch (113) is arranged on the circular arc edge (114), the distance between the deepest part of the notch (113) and the center of the first hole (111) is L3, and the range of L3 / L1 is 86%-93%.

3. The positive current collector tab of claim 1, wherein The shape of the notch (113) is a sector, the notch (113) forms an included angle α, and the range of the angle α is 72°-95°.

4. The positive current collector of claim 1, wherein The number of the second holes (112) and the number of the notches (113) are both 3, and the three second holes (112) and the three notches (113) are arranged around the first hole (111).

5. The positive current collector of claim 4, wherein The three second holes (112) and the three notches (113) are arranged one by one, and the corresponding notch (113) and the corresponding second hole (112) are both collinear with the center of the first hole (111).

6. The positive current collector of claim 5, wherein The outer periphery of the disc body (110) comprises a circular arc edge (114), the first hole (111) and the circular arc edge (114) share the same center, the circular arc edge (114) comprises at least half a circular periphery, two of the three notches (113) are centrally symmetrically distributed on the outer periphery of the circular arc edge (114), and the other notch (113) is located between the two notches (113).

7. A cylindrical lithium-ion battery, characterized by The positive electrode current collector disc (100), the winding core (200), the negative electrode current collector disc (300), the cap (400) and the shell (500) according to any one of claims 1-6 are connected, the disc body (110) of the positive electrode current collector disc is connected with the winding core (200), and the tail body (120) of the positive electrode current collector disc (100) is connected with the cap (400).

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