Positive collector plate and cylindrical lithium ion battery

Abstract

The invention provides a positive current collector plate and a cylindrical lithium ion battery, the positive current collector plate comprises a plate body and a tail body extending from the plate body, the plate body is provided with a first hole located in the middle and at least one second hole located in the periphery of the first hole, the outer periphery of the plate body is also provided with at least one notch, and the tail body is provided with a plurality of through holes. The area of the disc body is S1, the area of the notch formed by taking the edge line of the outer periphery of the disc body as a reference is S2, the range of S2 / S1 is 0.5%-2%, and the area of the disc body is the area of the disc body when the first hole, the second hole and the notch are not formed. By arranging the notches on the outer periphery of the disc body and reasonably setting the sizes of the notches, on one hand, the exhaust efficiency can be improved so as to improve the safety of the battery, and on the other hand, the electrolyte injection efficiency can be improved, the electrolyte injection time can be shortened, 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, and in particular to a positive electrode current collecting disc and a cylindrical lithium-ion battery. Background Art

[0002] According to the packaging form, lithium batteries can be divided into three forms: square, cylindrical and soft pack. Among them, cylindrical lithium-ion batteries have gradually become a hot spot in lithium battery research due to their good consistency, high production efficiency, and strong heat dissipation capacity at the system level. Cylindrical batteries are usually packaged in cylindrical steel shells. The bare cell is made by winding process to form a cylindrical core. The cap is located on the top of the battery and is connected to the positive electrode in the core through the positive current collector.

[0003] In the related art, the positive collector disk generally includes a disk body and a tail body extending integrally from the edge of one side of the disk body. During the assembly process, the disk body of the positive collector disk needs to be welded to the positive end of the core, and the tail body of the positive collector disk is welded to the cap to achieve electrical connection between the core and the cap. It is understandable that when a cylindrical lithium-ion battery is in use, if a short circuit or other thermal runaway occurs in the battery cell, a large amount of gas will be generated in the steel shell. Since the disk body is welded to the positive end of the core, the disk body will prevent the gas from being discharged from one side of the cap, thereby increasing the safety risk of the battery. In addition, due to the higher requirements for battery capacity and energy density, the current design of cylindrical lithium-ion batteries has a higher requirement for the assembly ratio, and the higher assembly ratio leads to a long injection time and reduced injection efficiency, which ultimately increases the battery manufacturing cost. Summary of the invention

[0004] The embodiments of the present application provide a positive electrode current collecting disk and a cylindrical lithium-ion battery to at least solve the technical problems of low liquid injection efficiency and low exhaust rate of existing cylindrical lithium-ion batteries.

[0005] A first aspect of the present application provides a positive current collector disk for a cylindrical lithium-ion battery, the positive current collector disk comprising a disk body and a tail body extending from the disk body, the disk body being provided with a first hole located in the middle thereof and at least one second hole located on the periphery of the first hole, the disk body being further provided with at least one notch on the outer periphery, the area of ​​the disk body being S1, the area of ​​the notch formed with the outer periphery edge line of the disk body being S2, the range of S2 / S1 being 0.5% to 2%, wherein the area of ​​the disk body is the area of ​​the disk body when the first hole, the second hole and the notch are not provided.

[0006] The positive electrode current collecting disk according to the embodiment of the present application has at least the following beneficial effects:

[0007] By providing a notch on the outer periphery of the disk body and by reasonably setting the size of the notch, on the one hand, when a short circuit or thermal runaway occurs inside the battery and a large amount of gas is produced, part of the gas can be diverted through the notch, thereby improving the exhaust efficiency and improving the safety of the battery; on the other hand, during the injection process, when the electrolyte flows into the disk surface of the disk body, part of the electrolyte will flow directly into the battery through the first hole and the second hole, while part of the electrolyte will reach the outer periphery of the disk body along the disk surface. Due to the presence of the notch, this part of the electrolyte will flow into the battery along the notch, thereby improving the electrolyte injection efficiency, reducing the injection time, improving the production efficiency, and reducing 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 6% to 13%, it is possible to take into account the injection efficiency and exhaust efficiency of the positive electrode collector disc while ensuring a good welding effect between the positive electrode collector disc and the winding core.

[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 4% to 12%, it is possible to ensure a good welding effect between the positive current collector and the winding core while taking into account the injection efficiency and exhaust efficiency of the positive current collector.

[0010] In a possible implementation, the outer periphery of the disk body includes an arc edge, the radius of the arc edge is L1, the first hole and the arc edge are cocentric, the distance from the center of the second hole to 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 50% to 64%, the structural strength of the connection 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 at the edge of the arc, the deepest part of the notch is at a distance L3 from the center of the first hole, and the range of L3 / L1 is 86% to 93%. By setting the range of L3 / L1 to 86% to 93%, it is possible to ensure a good welding effect between the positive current collector and the winding core while taking into account the injection efficiency and exhaust efficiency of the positive current collector.

[0012] In a possible implementation, the notch is fan-shaped and forms an angle α, and the range of α is 72° to 95°. Setting the angle α to 72° to 95° helps balance the efficiency of liquid injection and exhaust and the welding strength between the disc body and the coil 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 arranged around the first hole. The number of the notches corresponds to the number of the second holes, and both are set to 3, which is conducive to balancing the overall structural strength of the disk body and the efficiency of liquid injection and exhaust.

[0014] In a possible implementation, the three second holes are arranged in one-to-one correspondence with the three notches, and the corresponding notches and the second holes are collinear with the center of the first hole. The notches and the second holes are arranged collinear with the center of the first hole to facilitate processing, avoid notches occupying the welding area, and reduce the impact of notches on welding effects.

[0015] In a possible implementation, the outer periphery of the disk body includes an arc edge, the first hole and the arc edge are cocentric, the arc edge includes at least half a circumference, two of the three notches are centrally symmetrically distributed on the outer periphery of the arc edge, and the other notch is located between the two notches. Evenly distributing the three notches on the arc edge is conducive to more uniform injection effect and more rapid and uniform exhaust.

[0016] A second aspect of the present application provides a cylindrical lithium-ion battery, comprising any one of the positive current collector disc, winding core, negative current collector disc, cap and outer shell provided in the above embodiments, wherein the disc body of the positive current collector disc is connected to the winding core, and the tail body of the positive current collector disc is connected to the cap.

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

[0018] In the cylindrical lithium-ion battery of the embodiment of the present application, a notch is provided on the outer periphery of the positive electrode current collecting disk, which helps to improve the internal exhaust rate and liquid injection efficiency of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] Figure 1 is an exploded schematic diagram of a cylindrical lithium-ion battery provided in an embodiment of the present application;

[0021] Figure 2 It is a structural schematic diagram of a positive electrode current collector provided in an embodiment of the present application;

[0022] Figure 3 is a schematic diagram of an area S1 in a positive electrode current collecting disk provided in an embodiment of the present application;

[0023] Figure 4 is a schematic diagram of an area S2 in a positive electrode current collecting disk provided in an embodiment of the present application;

[0024] Figure 5 is a schematic diagram of an area S3 in a positive electrode current collecting disk provided in an embodiment of the present application;

[0025] Figure 6 is a schematic diagram of an area S4 in a positive electrode current collecting disk provided in an embodiment of the present application;

[0026] Figure 7 It is a structural schematic diagram of a positive electrode current collector provided in an embodiment of the present application;

[0027] Figure 8 yes Figure 2 Partial schematic diagram at point A in the middle.

[0028] Reference numerals:

[0029] 100-positive electrode current collecting disk, 110-disk body, 111-first hole, 112-second hole, 113-notch, 1131-seventh side, 1132-eighth side, 114-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-winding core, 210-positive terminal, 220-negative terminal;

[0031] 300-negative electrode collector plate;

[0032] 400-blocked shots;

[0033] 500-Housing. DETAILED DESCRIPTION

[0034] Embodiments of the present embodiment are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present embodiment, and should not be construed as limiting the present embodiment.

[0035] In the description of this embodiment, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and 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, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this embodiment.

[0036] In the description of this embodiment, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0037] In the description of this embodiment, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this embodiment based on the specific content of the technical solution.

[0038] The cylindrical lithium-ion batteries provided in the embodiments of the present application include various size series, such as 21 series (cylindrical lithium-ion batteries with an outer diameter of 21 mm) and 46 series (cylindrical lithium-ion batteries with an outer diameter of 46 mm), which are not limited here. Figure 1 As shown, the cylindrical lithium-ion battery includes a positive electrode current collecting disk 100, a winding core 200, a negative electrode current collecting disk 300, a cap 400 and a shell 500, wherein the positive terminal 210 of the winding core 200 is connected to the cap 400 through the positive electrode current collecting disk 100, and the negative terminal 220 of the winding core 200 is connected to the shell 500 through the negative electrode current collecting disk 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, which is used to be electrically connected to an external electrical device.

[0039] like Figure 2 As shown, the positive electrode current collecting disc 100 includes a disc body 110 and a tail body 120 connected to each other, wherein the disc body 110 is used to connect to the positive terminal 141 of the winding core 200, and the tail body 120 is used to connect to 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 method well 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 method, and in order to ensure the stability of the connection and the structural strength, it is preferably an integral connection.

[0040] In order to match the circular cross section of the winding core 200 and facilitate welding between the disk body 110 and the winding core 200, the disk body 110 is shaped as 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 in sequence, and the tail body 120 includes a fifth side 121 and a sixth side 122 along its length direction, and a fourth side 123 away from the disk body 110, the two ends of the fifth side 121 are respectively connected to the fourth side 123 and the first side 115, and the two ends of the sixth side 122 are respectively connected to the fourth side 123 and the second side 116, thereby, Figure 2 From the perspective of the tail body 120, the tail body 120 is also a closed axisymmetric figure extending from one end of the disc body 110. It should be noted that the third side 117 is a virtual side line proposed for the convenience of describing the disc body 110. There is no such side in the actual product. Figure 2 Dotted lines are used to mark the difference. Figure 1 It can also be understood that when the positive electrode current collecting disk is assembled to the cylindrical lithium-ion battery, the tail body 120 will be bent near the third side 117, and its distal end will be located above the closed axially symmetrical figure formed by the disk body 110.

[0041] As mentioned above, the shape of the disk body 110 is a closed axially symmetrical figure composed of the first side 115, the arc edge 114, the second side 116 and the third side 117 connected end to end. Therefore, the disk body 110 is not a complete circular shape when viewed as a whole, but the disk body 110 can be regarded as a circular component with respect to the arc edge 114, and the diameter of the arc edge 114 is the diameter of the disk body 110. In this case, the diameter of the disk body 110 is the longest line segment between two points on the arc edge 114. According to actual needs, the diameter of the disk body 110 is, for example, 15-23 mm. The disk body 110 ensures a larger contact area between the disk body 110 and the winding core 200 within the preferred diameter range, increases the weldable area, and expands the adaptability range of the welding 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 at the periphery of the first hole 111, wherein the first hole 111 is used to inject electrolyte into the battery, and the second hole 112 is used to assist electrolyte infiltration. It should be noted that the center of the disk body 110 may be the center of the circle corresponding to the arc edge 114.

[0043] It is understood that the winding core 200 is made by a winding process, and a circular winding core hole is formed at the center of the winding core 200 after winding. 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 is understood that the diameters of the first hole 111 and the second hole 112 can be specifically selected based on the balance between the injection efficiency and the weldable area.

[0044] Furthermore, the disc body 110 is also provided with a notch 113 on the outer periphery. Figure 2 From the perspective of the structure, the notch 113 is a structure formed by the outer periphery of the disk body 110 being concave inward toward the center of the disk body. For example, the notch 113 can be formed by removing material from the outer periphery of the disk body 110 through various methods such as mechanical cutting and laser cutting.

[0045] It is understandable that at least one notch 113 needs to be provided to facilitate auxiliary exhaust and auxiliary liquid injection at the outer periphery of the disk body 110. Of course, in order to further improve the exhaust efficiency and liquid injection efficiency, multiple notches 113 can be provided, and the multiple notches 113 are evenly spaced and distributed on the outer periphery of the disk body 110, for example, the number of notches 113 can be set to 3.

[0046] By the above method, various shapes of notches 113 can be formed on the outer periphery of the disk body 110. For example, the notches 113 are fan-shaped, such as Figure 8 As shown, in this case, the gap 113 is defined by the seventh side 1131, the eighth side 1132 and the reference line of the outer periphery of the disk body 110, wherein the reference line can refer to Figure 3 and Figure 4 The dotted line at the notch 113 in the figure is used for illustration, and the dotted line represents the shape of the disc body 110 when the notch 113 is not cut out of the disc body 110, and the dotted line is obtained by extending the outer periphery of the disc body 110 according to the direction of 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 providing the notch 113 on the outer periphery of the disk body 110, on the one hand, when a short circuit or thermal runaway occurs inside the battery and a large amount of gas is produced, part of the gas can be diverted through the notch 113, thereby improving the exhaust efficiency and improving the safety of the battery; on the other hand, during the injection process, when the electrolyte flows into the disk surface of the disk body 110, part of the electrolyte will flow directly into the battery through the first hole 111 and the second hole 112, while part of the electrolyte will reach the outer periphery of the disk body 110 along the disk surface of the disk body 110. Due to the presence of the notch 113, this part of the electrolyte will flow into the battery along the notch 113, thereby improving the electrolyte injection efficiency, reducing the injection time, improving the production efficiency, and reducing the manufacturing cost of the battery. It is understandable that the art usually adopts the method of opening pores inside the disc body 110 to improve the liquid injection efficiency, and in the design process, it is also necessary to balance the weldable area of ​​the disc body itself, etc., in order to facilitate welding with the winding core 200 and design welding tooling and fixtures. The present application minimizes the adverse effects on the disc body 110 by opening a notch 113 on the outer periphery to assist in exhaust and liquid injection. For example, by reasonably designing the size and shape of the notch 113, the impact on the welding of the disc body 110 can be effectively avoided.

[0048] like Figure 3 and Figure 4 As shown, in some embodiments, the area of ​​the plate body 110 is S1, the area of ​​the notch 113 is S2, and the range of S2 / S1 is 0.5% to 2%, that is, 0.5%≤S2 / S1≤2%. For example, S1 is 229.14 mm 2 , S2 is 2.94mm 2 , S2 / S1 is 1.3%. The area S1 of the disk body 110 refers to the disk surface area of ​​the disk body 110, that is, the area of ​​the disk body 110 when the first hole 111, the second hole 112 and the notch 113 are not provided. For example, as shown in the figure, S1 is the area of ​​the closed figure defined by the arc edge 114 and the third side 117. The area S2 of the notch 113 refers to the total area of ​​all the notches 113 on the disk body 110. It can be further understood that, for only a single notch 114, its area refers to the area defined by the edge line of the outer periphery of the disk body 110 as the reference line and the boundary line of the notch 113 itself. For example, the area S2 of the aforementioned fan-shaped notch 113 is the area of ​​the fan-shaped area defined by the seventh side 1131, the eighth side 1132 and the reference line of the outer periphery of the disk body 110.

[0049] It is understandable that if the area S2 of the notch 113 is too small, on the one hand, during the injection process, the notch 113 does not significantly improve the injection efficiency, and there is also a risk of electrolyte overflow, which can cause the shell to be contaminated by the electrolyte, rust, and even the battery to be scrapped. In addition, it is necessary to increase manpower to deal with the overflow problem, which will increase the manufacturing cost; on the other hand, when the battery is short-circuited or other thermal runaway conditions occur during use, the gas generated inside the battery cannot be discharged in time through the notch 113, and the effect of improving battery safety is limited. On the contrary, if the area S2 of the notch 113 is too large, 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 winding core 200, and the overcurrent capacity of the welding position does not meet the requirements, resulting in excessive overcurrent temperature rise, causing subsequent safety problems such as thermal control, and the safety performance of the battery is reduced. 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 winding core 200 while taking into account the injection efficiency and exhaust efficiency of the disc body 110.

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

[0051] It is understandable that if the area S3 of the second hole 112 is too small, on the one hand, during the injection process, the injection time increases, which will lead to a decrease in the injection efficiency, and there will also be a risk of electrolyte overflow, resulting in problems such as the shell being contaminated by the electrolyte, rusting, and even the battery being scrapped. In addition, it is necessary to increase manpower to deal with the overflow problem, which will increase the manufacturing cost; on the other hand, when a short circuit or other thermal runaway occurs during the use of the battery, the gas generated inside the battery cannot be discharged in time through the second hole 112, and the effect of improving the safety of the battery is limited. On the contrary, if the area S3 of the second hole 112 is too large, the second hole 112 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 winding core 200, and the overcurrent capacity of the welding position does not meet the requirements, resulting in excessive overcurrent temperature rise, causing subsequent safety problems such as thermal control, and the safety performance of the battery is reduced. 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 winding core 200 while taking into account the injection efficiency and exhaust efficiency of the disc body 110.

[0052] Furthermore, if Figure 3 and Figure 6 As shown, in some embodiments, the area of ​​the first hole 111 is S4, and the range of S4 / S1 is 4% to 12%, that is, 4%≤S4 / S1≤12%. For example, the area of ​​the first hole 111 is 19.63mm 2 , S1 is 229.14mm 2 , S4 / S1 is 8.6%. The first hole 111 is located at the center of the disk body 110, and the number thereof is one. Therefore, the area S4 of the first hole 111 here only refers to the area of ​​the first hole 111 itself.

[0053] It is understandable that if the area S4 of the first hole 111 is too small, on the one hand, during the injection process, due to the narrow injection channel, the electrolyte is difficult to be injected into the battery, and the injection time increases, which will lead to a decrease in the injection efficiency; on the other hand, when a short circuit or other thermal runaway occurs during the use of the battery, the gas generated inside the battery cannot be discharged in time through the first hole 111, which reduces the safety of the battery. On the contrary, if the area S4 of the first hole 111 is too large, the first hole 111 will occupy the welding area on the disk surface of the disk body 110, resulting in a reduction in the welding area of ​​the positive terminal 210 of the disk body 110 and the winding core 200, and the current capacity of the welding position does not meet the requirements, thereby causing excessive overcurrent temperature rise, causing subsequent safety problems such as thermal control, and the safety performance of the battery is reduced. By setting the range of S4 / S1 to 4% to 12%, it is possible to take into account the injection efficiency and exhaust efficiency of the disk body 110 while ensuring a good welding effect between the disk body 110 and the winding core 200.

[0054] As mentioned above, the outer periphery of the disk body 110 includes an arc edge 114. Figure 7 As shown, in some embodiments, the first hole 111 and the arc edge 114 are arranged co-centrically, the radius of the arc edge 114 is L1, the distance from the center of the second hole 112 to the center of the first hole 111 is L2, and the range of L2 / L1 is 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 size of the cylindrical lithium-ion battery is basically fixed, that is, the outer shell diameter of the cylindrical lithium-ion battery is determined, so the diameter of the disk body 110 of the positive electrode current collecting disk 100 assembled into the outer shell is basically determined, and because the first hole 111 is located at the center of the disk body 110, if L2 / L1 is too large, the second hole 112 and the notch 113 are too close. In this way, the structural strength of the connecting part between the second hole 112 and the notch 113 may be insufficient, and there is a risk of breaking. Moreover, once this part is broken, metal chips will be generated, and the burrs generated at the fracture are also easy to deform inward and pierce the diaphragm. Both metal chips and burrs may cause short circuit failure of the battery, posing a safety risk. On the contrary, if L2 / L1 is too small, the second hole 112 is too close to the first hole 111, so that the structural strength of the connecting portion between the second hole 112 and the first hole 111 may be insufficient, and there is a risk of breaking. In addition, once this part breaks, metal chips will be generated, and the burrs generated at the fracture will also easily deform inward and pierce the diaphragm. Both metal chips and burrs may cause short circuit failure of the battery, posing a safety risk. By setting the range of L2 / L1 to 50% to 64%, the structural strength of the connecting portion between the first hole 111, the second hole 112 and the notch 113 can be ensured, thereby improving the safety of the battery.

[0056] As mentioned above, the shape of the disc body 110 is a closed axisymmetric figure composed of the first side 115, the arc edge 114, the second side 116 and the third side 117 connected end to end. In order to make the notch 113 play a better role in assisting exhaust and liquid injection, in some embodiments, the notch 113 is arranged at the outer periphery of the arc edge 114. At the same time, the deepest distance of the notch 113 from 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 9.1mm, L3 is 8.11mm, 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 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] It is understandable that if L3 / L1 is too small, the depth of the notch 113 is deeper, so the area of ​​the notch 113 is larger (taking the fan-shaped notch 113 as an example, assuming that the angle α between the seventh side 1131 and the eighth side 1132 remains unchanged). At this time, 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 winding core 200. The current capacity of the welding position does not meet the requirements, resulting in excessive overcurrent temperature rise, causing subsequent safety problems such as thermal control, and reducing the safety performance of the battery. On the contrary, if L3 / L1 is too large, the depth of the notch 113 is shallow, so the area of ​​the notch 113 will be smaller. On the one hand, during the injection process, the notch 113 does not significantly improve the injection efficiency, and there is also a risk of electrolyte overflow, which causes the shell to be contaminated by the electrolyte, rust, and even the battery to be scrapped. In addition, it is necessary to increase manpower to deal with the overflow problem, which will increase the manufacturing cost. On the other hand, when the battery is short-circuited or other thermal runaway conditions occur during use, the gas generated inside the battery cannot be discharged in time through the notch 113, and the effect on improving battery safety is limited. By setting the range of L3 / L1 to 86% to 93%, it is possible to take into account the injection efficiency and exhaust efficiency of the disc body 110 while ensuring a good welding effect between the disc body 110 and the winding core 200.

[0058] In some embodiments, Figure 2 and Figure 8 As shown, the shape of the notch 113 is fan-shaped, and the notch 113 forms an angle α, and the range of α is between 72° and 95°, that is, 72°≤α≤95°. If the angle α is too small, the difficulty of the electrolyte passing through becomes greater during the injection, the injection flow rate becomes smaller, the injection time becomes longer, and the production efficiency decreases. If the angle α is too large, when the subsequent disc 110 is welded to the positive terminal 210 of the winding core 200, it affects the positioning and pressing of the welding tooling. The welding tooling needs to occupy other disc positions, which will cause the welding area to be reduced, the welding current capacity to be reduced, and the temperature rise at the welding point to increase, affecting the overall performance of the battery. In some embodiments, the fan-shaped notch 113 takes the radius of the arc edge 114 as the axis of symmetry. Setting α to 72° to 95° helps to balance the injection exhaust efficiency and the welding strength between the disc 110 and the winding core 200.

[0059] In some embodiments, the number of the notches 113 is 3, the number of the second holes 112 is 3, the three second holes 112 are arranged around the first hole 111, the positions of the second holes 112 are arranged corresponding to the notches 113, and the first hole 111 is arranged at the center of the arc edge 114. The number of notches 113 corresponds to the number of second holes 112, and both are set to 3, which is conducive to balancing the overall structural strength of the disk body 110 and the liquid injection and exhaust efficiency.

[0060] Furthermore, 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 electrode 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 conducive to 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 reduction in the welding area and affecting the welding effect.

[0061] Further, in some embodiments, the arc edge 114 includes at least half of the circumference, two of the three notches 113 are symmetrically distributed around the center of the circle, and the other notch 113 is at the same distance from the two notches 113. Evenly distributing the three notches 113 on the arc edge 114 is conducive to more uniform injection effect and more rapid and uniform exhaust.

[0062] The effects of the present application are further described below with specific examples and comparative examples.

[0063] It should be noted that the following embodiments and comparative examples of the present application are designed and manufactured based on the 2170 cylindrical lithium-ion battery commonly used in the art. Therefore, except for manufacturing the positive electrode collector according to the aforementioned structure, other components and materials can be obtained by referring to the 2170 cylindrical lithium-ion battery. For example, the positive electrode sheet, the negative electrode sheet and the electrolyte can be obtained by referring to the following preparation method:

[0064] Preparation of positive electrode sheet: Take lithium nickel cobalt manganese oxide, carbon nanotube conductive agent, conductive carbon black, and polyvinylidene fluoride PVDF binder as solid substances of positive electrode slurry, disperse the solid substances in N-methyl-2-pyrrolidone, mix them evenly in a homogenizer, apply the slurry on both sides of aluminum foil, and dry to obtain a positive electrode sheet.

[0065] Preparation of negative electrode sheet: Take negative electrode active material, acetylene black conductive agent, thickener (hydroxymethyl cellulose), and polyacrylate binder as solid substances of negative electrode slurry, disperse the solid substances in deionized water, mix them evenly in a homogenizer, apply the slurry on both sides of copper foil, and dry to obtain negative electrode sheet.

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

[0067] The components and materials obtained in the above manner can be assembled according to the known technology in the art to obtain an experimental cylindrical lithium-ion battery. For example, after the positive electrode sheet and the negative electrode sheet are rolled, slit, and die-cut, they are wound together with the diaphragm, and the positive electrode sheet, the negative electrode sheet, and the diaphragm are wound by a winding machine to form a winding core 200, and the positive electrode tabs and negative electrode tabs are cut and stacked at both ends of the winding core 200, and then the positive electrode collector disc 100 and the negative electrode collector disc 300 are welded to the winding core 200 respectively, and then the negative electrode collector disc 300 is welded to the shell 500, and an insulating sheet is placed above the positive electrode collector disc 100, and the positive electrode collector disc 100 is welded to the cap 400, and the injection, sealing, and formation processes are completed to obtain an experimental cylindrical lithium-ion battery.

[0068] Embodiment 1:

[0069] Embodiment 1 provides a cylindrical lithium-ion battery, which includes a positive current collector disk 100, and the positive current collector disk 100 includes a disk body 110 and a tail body 120 extending from the disk body 110. The disk body 110 of the positive current collector disk 100 faces the winding core 200, and the bent tail body 120 is away from the winding core 200 and faces the cap 400, and is used to be electrically connected to the cap 400. The disk body 110 includes an arc edge 114, a first hole 111 located in the middle thereof and co-centered with the arc edge 114, and three second holes 112 located on the periphery of the first hole 111, and three fan-shaped notches 113 are also provided on the outer periphery of the arc edge 114, and the centers of the first holes 111, the second holes 112 and the notches 113 are colinear, and the positive current collector disk 100 also meets the following parameters:

[0070] The area S1 of the disk 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 19.63mm 2 The area S3 of the second hole 112 is 21.21mm 2 The diameter L1 of the 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; the angle α of the notch 113 is 80°.

[0071] From the above, it can be seen that in the positive electrode current collecting disk, S2 / S1=1.3%; S3 / S1=9.26%; S4 / S1=8.6%; L2 / L1=56.37%; L3 / L1=89.12%.

[0072] Comparative Example 1:

[0073] Comparative Example 1 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 100 , and the difference between Comparative Example 1 and Example 1 is that S2 / S1 = 0.2%.

[0074] Comparative Example 2:

[0075] Comparative Example 2 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 100 , and the difference between Comparative Example 2 and Example 1 is that S2 / S1 = 4%.

[0076] Comparative Example 3:

[0077] Comparative Example 3 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 100, and the difference between the comparative example 3 and the embodiment 1 is that: S3 / S1=3%.

[0078] Comparative Example 4:

[0079] Comparative Example 4 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 100, and the difference between the comparative example 4 and the embodiment 1 is that: S3 / S1=18%.

[0080] Comparative Example 5:

[0081] Comparative Example 5 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 100, and the difference between the comparative example 5 and the embodiment 1 is that: S4 / S1=2%.

[0082] Comparative Example 6:

[0083] Comparative Example 6 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 100, and the difference between the comparative example 6 and the embodiment 1 is that: S4 / S1=16%.

[0084] Comparative Example 7:

[0085] Comparative Example 7 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 100, which is different from Example 1 in that: L2 / L1=40%.

[0086] Comparative Example 8:

[0087] Comparative Example 8 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 100, which is different from Example 1 in that: L2 / L1=70%.

[0088] Comparative Example 9:

[0089] Comparative Example 9 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 100, and the difference between the comparative example 9 and the embodiment 1 is that L3 / L1=83.3% and α is 34°.

[0090] Comparative Example 10:

[0091] Comparative Example 10 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 100, and the difference between the comparative example 1 and the embodiment 1 is that L3 / L1=96% and α is 170°.

[0092] Comparative Example 11:

[0093] Comparative Example 11 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting plate 100, which differs from Example 1 in that: the first holes 111, the second holes 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] Table 1 below evaluates the structural strength effect, liquid injection rate and welding effect of the positive electrode current collecting disc 100 manufactured in the above-mentioned embodiment and comparative example.

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

[0096] The specific test method for the injection rate is as follows: the positive electrode current collecting disk 100 prepared in the above-mentioned embodiments and comparative examples is assembled into an experimental cylindrical lithium-ion battery, and the sample preparation process is transferred to the injection stage, and each experimental cylindrical lithium-ion battery is evacuated to a negative pressure of -90 kPa and then the injection is started, 6.5 g of electrolyte is injected into the liquid holding cup for the first injection, and the electrolyte in the liquid holding cup is pressed into the battery mouth space with a pressure rod at a displacement speed of 0.5 mm / s. The electrolyte at the battery mouth slowly flows into the battery through the positive electrode current collecting disk 100, the pressure rod is continuously pressed down, and the electrolyte is continuously injected into the battery through the positive electrode current collecting disk 100. The time from the start of the pressure rod pressing down to the start of overflow is recorded for each embodiment and comparative example.

[0097] The specific test method for the welding effect is as follows: the positive electrode current collecting disc 100 manufactured in the above-mentioned embodiment and the comparative example is assembled into an experimental cylindrical lithium-ion battery, a through hole with a diameter of 3 mm is drilled on the cap 400 of the experimental cylindrical lithium-ion battery, a temperature control line is passed through the through hole, and affixed to the weld mark of the positive electrode current collecting disc 100 and the positive terminal 210 of the winding core 200, and the cap 400 is sealed after liquid injection according to the normal sample preparation process, and the battery is divided into different caps to make a qualified cylindrical lithium-ion battery, and 10 cycles of charge and discharge are performed at a high rate of 2C. After 10 cycles of charge and discharge, the temperature data of the welding area collected by the temperature control line is obtained, and the maximum value Tmax within the temperature fluctuation range within 10 cycles is taken and recorded.

[0098] Table 1

[0099]

[0100]

[0101] It can be seen from Table 1 that if S2 / S1 is too large, the structural strength of the positive electrode current collecting disc 100 will be reduced, and the welding effect of the positive electrode current collecting disc 100 will also be affected, resulting in excessive temperature rise in the welding area, but the overflow time can be increased; on the contrary, if S2 / S1 is too small, although the structural strength of the positive electrode current collecting disc 100 and the temperature rise in the welding area can be guaranteed within a reasonable range, the injection efficiency will be reduced, resulting in faster overflow. Therefore, setting S2 / S1 within a reasonable range can balance the structural strength, injection rate and welding effect of the positive electrode current collecting disc 100.

[0102] It can be seen from Table 1 that if S3 / S1 is too large, the structural strength of the positive electrode current collecting disc 100 will also be reduced, and the welding effect of the positive electrode current collecting disc 100 will also be affected, resulting in excessive temperature rise in the welding area; on the contrary, if S3 / S1 is too small, although the structural strength of the positive electrode current collecting disc 100 and the temperature rise in the welding area can be guaranteed within a reasonable range, the injection efficiency will be reduced, resulting in faster overflow. Therefore, setting S3 / S1 within a reasonable range can balance the structural strength, injection rate and welding effect of the positive electrode current collecting disc 100.

[0103] It can be seen from Table 1 that if S4 / S1 is too large, the structural strength of the positive electrode current collecting disc 100 will also be reduced, and the welding effect of the positive electrode current collecting disc 100 will also be affected, resulting in excessive temperature rise in the welding area, but the injection time can be shortened, thereby improving the injection efficiency and reducing the risk of overflow; on the contrary, if S4 / S1 is too small, while ensuring the structural strength of the positive electrode current collecting disc 100 and ensuring that the temperature rise in the welding area is within a reasonable range, the risk of overflow is increased, resulting in the problem of electrolyte overflow in a shorter time; therefore, setting S4 / S1 within a reasonable range can balance the structural strength, injection rate and welding effect of the positive electrode current collecting disc 100.

[0104] It can be seen from Table 1 that if L2 / L1 is too large or too small, the structural strength of the positive electrode current collecting disc 100 will be affected. Setting L2 / L1 within a reasonable range can ensure the structural strength of the positive electrode current collecting disc 100.

[0105] It can be seen from Table 1 that if L3 / L1 is too small and the angle α is too small, the structural strength of the positive electrode current collecting disc 100 will be reduced; conversely, if L3 / L1 is too large and the angle α is too large, although the structural strength of the positive electrode current collecting disc 100 can be guaranteed, the temperature rise in the welding area will be too high. Therefore, setting L3 / L1 and the angle α within a reasonable range can ensure the structural strength, injection efficiency and welding effect of the positive electrode current collecting disc 100.

[0106] It can be seen from Table 1 that if the first hole 111 , the second hole 112 and the notch 113 are not arranged in a colinear manner, the welding effect of the positive electrode current collecting disk 100 will be affected, thereby causing excessive temperature rise in the welding area.

[0107] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present implementation. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0108] Although examples of the present embodiment have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may 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 electrode current collector for a cylindrical lithium-ion battery, characterized in that: The invention comprises a disc body (110) and a tail body (120) extending from the disc body (110), wherein the disc body (110) is provided with a first hole (111) located in the middle thereof and at least one second hole (112) located on the periphery of the first hole (111), and the disc body (110) is further provided with at least one notch (113) on the periphery thereof, the area of ​​the disc body (110) is S1, the area of ​​the notch (113) formed with the periphery line of the disc body (110) as a reference is S2, and the range of S2 / S1 is 0.5% to 2%, wherein the area of ​​the disc body (110) is the area of ​​the disc body (110) when the first hole (111), the second hole (112) and the notch (113) are not provided.

2. The positive electrode current collecting disk according to claim 1, characterized in that: The area of ​​the second hole (112) is S3, and the range of S3 / S1 is 6% to 13%.

3. The positive electrode current collecting disk according to claim 1, characterized in that: The area of ​​the first hole (111) is S4, and the range of S4 / S1 is 4% to 12%.

4. The positive electrode current collecting disk according to any one of claims 1 to 3, characterized in that: The outer periphery of the disk body (110) includes an arc edge (114), the radius of the arc edge (114) is L1, the first hole (111) and the arc edge (114) are cocentric, the distance from the center of the second hole (112) to the center of the first hole (111) is L2, and the range of L2 / L1 is 50% to 64%.

5. The positive electrode current collecting disk according to claim 4, characterized in that: The notch (113) is arranged at the arc edge (114), the deepest part of the notch (113) is at a distance L3 from the center of the first hole (111), and the range of L3 / L1 is 86% to 93%.

6. The positive electrode current collecting disk according to any one of claims 1 to 3, characterized in that: The notch (113) is in a fan-shaped shape, and the notch (113) forms an angle α, and the range of α is 72° to 95°.

7. The positive electrode current collecting disk according to any one of claims 1 to 3, characterized in that: The number of the second holes (112) and the number of the notches (113) are both three, and the three second holes (112) and the three notches (113) are all arranged around the first hole (111).

8. The positive electrode current collecting disk according to claim 7, characterized in that: The three second holes (112) and the three notches (113) are arranged in one-to-one correspondence, and the corresponding notches (113) and the second holes (112) are all collinear with the center of the first hole (111).

9. The positive electrode current collecting disk according to claim 8, characterized in that: The outer periphery of the disk body (110) includes an arc edge (114); the first hole (111) and the arc edge (114) are cocentric; the arc edge (114) includes at least half a circumference; two of the three notches (113) are centrally symmetrically distributed on the outer periphery of the arc edge (114); and the other notch (113) is located between the two notches (113).

10. A cylindrical lithium-ion battery, characterized in that: The invention comprises a positive electrode current collecting disc (100), a winding core (200), a negative electrode current collecting disc (300), a cap (400) and a housing (500) according to any one of claims 1 to 9, wherein the disc body (110) of the positive electrode current collecting disc is connected to the winding core (200), and the tail body (120) of the positive electrode current collecting disc (100) is connected to the cap (400).

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