Positive collector plate and cylindrical lithium battery

Abstract

The utility model provides a positive current collector plate and a cylindrical lithium battery, the upper surface of the positive current collector plate is provided with a protruding part, the lower surface of the positive current collector plate is provided with a concave part corresponding to the protruding part, and when at least two positive current collector plates are stacked, the protruding part of the lower positive current collector plate is matched with the concave part of the upper positive current collector plate; according to the cylindrical lithium battery, the whole plate surface is separated, so that the interaction force between the contact surfaces of the upper and lower positive current collecting plates is reduced, the situation that the upper positive current collecting plate is adsorbed while the lower positive current collecting plate is adsorbed can be reduced, and the situation that two positive current collecting plates are assembled on one cylindrical lithium battery is reduced; and the production yield of the cylindrical lithium battery is improved.

Description

Technical Field

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

[0002] Lithium batteries can be categorized into three types based on packaging: prismatic, cylindrical, and pouch. Cylindrical lithium batteries have become a hot topic in lithium battery research due to their consistent performance, high production efficiency, and robust heat dissipation capabilities. Cylindrical batteries are typically packaged in a cylindrical steel casing. Bare cells are manufactured using a winding process to form a cylindrical core. The cap is located on top of the battery and welded to the positive electrode in the core via a positive current collector.

[0003] In existing cylindrical lithium battery technologies, the thickness of the positive electrode collector disc is generally thin, normally ranging from 0.1-0.3mm, with 0.2mm being the most common. Due to the thinness of the positive electrode collector disc material, the entire positive electrode collector disc has poor deformation resistance, which can easily cause the disc surface to bend and deform during production, affecting the welding area on the disc surface, resulting in cold welds and hot spots when welding the positive electrode collector disc surface to the positive electrode side of the winding core. To avoid these problems, the flatness and surface roughness of the entire positive electrode collector disc surface are very high.

[0004] However, during the production process, the positive collector discs are stacked before being loaded. The suction nozzle on the transfer equipment then moves from top to bottom, sucking the disc onto the surface of the disc body, and then the equipment nozzle tooling moves and places it on the positive side of the winding core for welding to achieve electrical connection. However, because the surface of the positive collector disc is very smooth, with very low roughness, it is relatively thin and has very high flatness requirements. Therefore, when the suction nozzle picks up the positive collector discs, two or more positive collector discs will be attracted together, resulting in stacking. This ultimately leads to poor welding, reduced production yield, and increased manufacturing costs. Utility Model Content

[0005] The embodiments of the present application provide a positive electrode current collecting disc and a cylindrical lithium battery, so as to at least solve the technical problem that the positive electrode current collecting discs in the existing positive electrode current collecting discs are easily overlapped during the transfer process when they are stacked.

[0006] The first embodiment of the present application provides a positive electrode current collecting plate for a cylindrical lithium battery, comprising:

[0007] A disc body and a tail body are connected to each other, the disc body is used to connect the winding core, the tail body is used to connect the cap, the disc body is provided with a first hole, the disc body includes an upper surface and a lower surface relative to each other along the thickness direction of the disc body, and the disc body also includes a protrusion arranged on the upper surface and a recessed portion arranged on the lower surface corresponding to the protrusion.

[0008] The positive electrode current collecting disk according to the embodiment of the present application has at least the following beneficial effects:

[0009] When at least two positive current collecting discs are stacked, the protrusion of the lower positive current collecting disc cooperates with the recessed portion of the upper positive current collecting disc to isolate the entire disc surface, thereby reducing the interaction force between the contact surfaces of the upper and lower positive current collecting discs. This can reduce the need to adsorb the lower positive current collecting disc while adsorbing the upper positive current collecting disc, reduce the situation of assembling two positive current collecting discs in one cylindrical lithium battery, and improve the production yield of cylindrical lithium batteries.

[0010] In one possible embodiment, the height of the protrusion along the thickness direction of the disk body is H1, the sum of the thickness of the disk body and the height of the protrusion along the thickness direction of the disk body is H2, and 36%≤H1 / H2≤58%, which is conducive to balancing the structural strength and anti-stacking effect of the protrusion.

[0011] In one possible embodiment, the outer edge of the disk body includes an arc-shaped edge, the radius of the arc-shaped edge is R, the disk body includes at least one protrusion and at least one corresponding recessed portion, the center of the protrusion farthest from the center of the arc-shaped edge is at a distance L1 from the center of the circle, 85%≤L1 / R≤95%, and designing the L1 / R ratio to 85%-95% is conducive to balancing the anti-stacking effect and production difficulty.

[0012] In one possible embodiment, the disk body further includes a second hole, which is located between the first hole and the protrusion. The diameter of the second hole is L2, and the diameter of the first hole is L3. 25% ≤ L2 / L3 ≤ 35%. Setting the ratio of L2 / L3 to 25% to 35% is beneficial to balancing the wetting effect and the weldable area of the disk body.

[0013] In one possible embodiment, the disc body further includes at least one recessed-protrusion combination, comprising three protrusions and three corresponding recessed portions, with the center lines connecting the three protrusions forming an isosceles triangle. This isosceles triangle arrangement helps distribute the forces exerted by the positive current collector disc above each protrusion, isolates the upper and lower positive current collector discs from contact, and prevents overlap.

[0014] In a possible implementation, the base angle of the isosceles triangle is α, 18°≤α≤37°. Setting α to 18°-37° is beneficial to balancing the production difficulty and structural strength of the protrusion.

[0015] In one possible embodiment, the perpendicular bisector on the base of the isosceles triangle overlaps with the radius of the arc-shaped edge, and the length of the base of the isosceles triangle is L4, 0.5mm≤L4≤2mm. Setting L4 to 0.5mm~2mm is beneficial to balancing the welding effect of the disk body and the structural strength of the protrusion.

[0016] In one possible embodiment, the disc body includes three groups of recessed and protruding assemblies spaced apart circumferentially, with two groups of recessed and protruding assemblies symmetrically distributed about the center of the circle, and the other group of recessed and protruding assemblies being equidistant from the first two groups. Evenly distributing the recessed and protruding assemblies circumferentially helps improve the isolation between the upper and lower positive current collector discs, while also distributing the force applied by the upper positive current collector disc and reducing deformation of the protruding portions.

[0017] In one possible embodiment, the recessed portion forms an inner cavity with an opening, the outer surface of the protrusion is curved, the length of the protrusion along the disk surface is L5, and the length of the opening along the disk surface is L6, where L5 ≥ L6. Because the outer surface of the protrusion is curved and its length is greater than or equal to the length of the opening, when the upper positive current collector disk is placed on the lower positive current collector disk, the opening of the upper recessed portion abuts against the outer surface of the protrusion, creating a gap between the upper and lower disks, further reducing contact between the upper and lower disks and preventing overlap.

[0018] A second embodiment of the present application provides a cylindrical lithium battery, comprising a positive electrode current collecting disc, an outer shell, a cap, a winding core, and a negative electrode current collecting disc according to any of the aforementioned embodiments, wherein the disc body of the positive electrode current collecting disc is connected to the winding core, and the tail body of the positive electrode current collecting disc is connected to the cap. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments of the present application. 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 any creative work.

[0020] Figure 1 1 is a schematic top view of a positive electrode current collecting disc provided in an embodiment of the present application;

[0021] Figure 2 yes Figure 1 A partial schematic diagram of the middle part;

[0022] Figure 3 1 is a cross-sectional schematic diagram of a positive electrode current collecting disk provided in an embodiment of the present application;

[0023] Figure 4 yes Figure 3 Partial schematic diagram of point B in the middle.

[0024] Reference numerals:

[0025] 110 - disk body, 111 - first hole, 112 - upper surface, 113 - lower surface, 114 - protrusion, 115 - recess, 116 - arcuate edge, 117 - second hole;

[0026] 120 tail bodies. DETAILED DESCRIPTION

[0027] Examples of the present embodiment are described in detail below. Examples of the embodiments 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 are not to be construed as limiting the present embodiment.

[0028] 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. They are only for the convenience of describing this embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on this embodiment.

[0029] In the description of this embodiment, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and is not to be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0030] In the description of this embodiment, unless otherwise clearly defined, terms such as setting, installing, and connecting 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.

[0031] Example 1:

[0032] Please refer to Figures 1 to 4The positive electrode current collector disc provided in the first embodiment includes a disc body 110 and a tail body connected to each other. The disc body 110 is used to connect to the winding core, and the tail body is used to connect to the cap. The disc body 110 is provided with a first hole 111. The disc body 110 includes an upper surface 112 and a lower surface 113 that are opposite to each other along the thickness direction of the disc body 110. The disc body 110 also includes a protrusion 114 provided on the upper surface 112 and a recessed portion 115 provided on the lower surface 113 corresponding to the protrusion 114. During the production process, multiple positive electrode current collector discs are stacked together. The protrusion 114 of the lower positive electrode current collector disc cooperates with the recessed portion 115 of the upper positive electrode current collector disc to isolate the entire disc surface, thereby reducing the interaction force between the contact surfaces of the upper and lower positive electrode current collector discs. This can reduce the possibility that the lower positive electrode current collector disc is also attracted when the upper positive electrode current collector disc is attracted, thus reducing the need to assemble two positive electrode current collector discs into a cylindrical lithium battery and improving the production yield of cylindrical lithium batteries.

[0033] Production process of the positive electrode current collecting disc: The lower surface 113 of the positive electrode current collecting disc is squeezed by a mold, thereby forming a recessed portion 115 on the lower surface 113. Since the positive electrode current collecting disc is relatively thin, squeezing the lower surface 113 to form the recessed portion 115 causes the upper surface 112 to protrude outward to form a protrusion 114.

[0034] In some embodiments, the axis of the protrusion 114 coincides with the axis of the recess 115 .

[0035] In some embodiments, the height of the protrusion 114 along the thickness direction of the disc body 110 is H1, and the sum of the thickness of the disc body 110 and the height of the protrusion 114 along the thickness direction of the disc body 110 is H2, and 36% ≤ H1 / H2 ≤ 58%. If the ratio H1 / H2 is too low, the height of the protrusion 114 is too low, the anti-lamination function is reduced, the welding risk increases, the cell scrap rate increases, and the manufacturing cost of the cell increases. If the ratio H1 / H2 is too large, the height of the protrusion 114 is too large. The positive electrode current collector disc is generally made of aluminum, which is a relatively soft material. If the height of the protrusion 114 is too high, the strength of the protrusion 114 is reduced, and deformation and dents are easily caused. When the positive electrode current collector discs are stacked during packaging, transportation, and production, the upper and lower positive electrode current collector discs cannot be stacked one-to-one, which will occupy a large amount of stacking height space, increase the frequency of loading, reduce production efficiency, and increase production costs. Setting the ratio of H1 / H2 to 36% to 58% is beneficial to balancing the structural strength and anti-lamination effect of the protrusion 114.

[0036] In some embodiments, the ratio of H1 / H2 is preferably 40% to 50%.

[0037] In some embodiments, the outer edge of the disk body 110 includes an arcuate edge 116 having a radius R. The disk body 110 includes at least one protrusion 114 and at least one corresponding recess 115. The distance between the center of the protrusion 114 farthest from the center of the arcuate edge 116 and the center of the circle is L1, and 85% ≤ L1 / R ≤ 95%. The protrusion 114 farthest from the center of the arcuate edge 116 is the outermost protrusion 114. The outermost protrusion 114 is too close to the edge of the disk surface. In the manufacturing process of the positive electrode current collector disk, it is difficult to stamp out the protrusion 114 so close to the edge, which increases production difficulty and reduces efficiency. Furthermore, the outermost protrusion 114 is relatively thin near the edge of the disc, with no surrounding material to support it. This results in low structural strength and is prone to deformation and denting. This occupies a considerable amount of space when stacking the positive current collector discs, increasing the number of loading operations, reducing production efficiency, and increasing manufacturing and labor costs. The outermost protrusion 114 is too far from the edge of the disc and too close to the central first hole 111, which can also be considered an edge. This makes it difficult to achieve this close proximity to the edge in the manufacturing process of the positive current collector disc. This increases the difficulty of stamping out the protrusion 114, reducing efficiency, and increasing production complexity. Designing the L1 / R ratio to 85%-95% is beneficial for balancing the anti-stacking effect and production difficulty.

[0038] To accommodate the circular cross-section of cylindrical lithium batteries, the outermost edge of the disc 110 is typically an arc-shaped edge 116. Since the tail of the positive current collector is bent during assembly, the portion of the disc 110 near the tail does not extend beyond the circle where the arc-shaped edge 116 is located, so this portion generally does not need to be an arc. In some embodiments, the arc-shaped edge 116 comprises at least half of the circumference, which can enhance the structural strength of the disc 110 while increasing its surface area, facilitating welding of the disc 110 to the winding core.

[0039] In some embodiments, the positive electrode current collecting disc composed of the disc body 110 and the tail body is axially symmetrical.

[0040] In some embodiments, the disc body 110 further includes a second hole 117 located between the first hole 111 and the protrusion 114. The diameter of the second hole 117 is L2, and the diameter of the first hole 111 is L3, with 25% ≤ L2 / L3 ≤ 35%. If the diameter L2 of the second hole 117 is too small, the wetting aid effect is difficult to achieve; if the diameter L2 of the second hole 117 is too large, the weldable area of the disc body 110 is reduced. Setting the L2 / L3 ratio between 25% and 35% helps balance the wetting effect and the weldable area of the disc body 110. It is understood that the number of second holes 117 can be determined based on the actual welding process. In some embodiments, the number of second holes 117 is three. In some embodiments, the center of the first hole 111 coincides with the center of the arcuate edge 116.

[0041] In some embodiments, the disc body 110 further includes at least one recessed-protrusion combination, comprising three protrusions 114 and corresponding three recessed portions 115. The line connecting the centers of the three protrusions 114 forms an isosceles triangle. Arranging the protrusions 114 in an isosceles triangle arrangement disperses the forces exerted by the positive current collector disc above them, with the isosceles design providing greater stability. Furthermore, the isosceles triangle arrangement helps isolate the upper and lower positive current collector discs from contact, preventing overlap.

[0042] In some embodiments, the base angle of the isosceles triangle is α, 18°≤α≤37°. If the angle α is too small, the height of the entire isosceles triangle will be reduced, the stability of the triangle formed by the three protrusions 114 will be affected, the structural strength will be reduced, the protrusions 114 will be easily deformed, and the anti-stacking function will not be achieved; when the angle α is too large, some protrusions 114 are too close to the second hole 117, and the difficulty of stamping the protrusions 114 increases. Setting α to 18°~37° is conducive to balancing the production difficulty of the protrusions 114 and the structural strength of the protrusions 114. It can be understood that an isosceles triangle includes two equal base angles and one vertex angle.

[0043] In some embodiments, the base angle α is preferably 20° to 30°.

[0044] In some embodiments, the perpendicular bisector on the base of the isosceles triangle overlaps with the radius of the curved edge 116, and the length of the base of the isosceles triangle is L4, where 0.5 mm ≤ L4 ≤ 2 mm. It is understood that the three sides of the isosceles triangle are two equal-length waists and a base. When L4 is too small, the triangular shape formed by the three protrusions 114 is too small, the structural strength is reduced, and the protrusions 114 are easily deformed. The positive current collector plates will occupy too much height space when stacked, resulting in increased loading times, reduced production efficiency, and increased manufacturing and labor costs. When L4 is too large, it will occupy too much welding area, resulting in a reduced welding area, reduced current carrying capacity after welding, and increased temperature rise at the weld, affecting the performance of the battery cell. Setting L4 to 0.5 mm to 2 mm helps balance the welding effect of the plate body 110 and the structural strength of the protrusions 114. Furthermore, L4 is preferably 0.8 mm to 1.5 mm. It is understood that the perpendicular bisector on the base of the isosceles triangle overlaps with the radius of the curved edge 116, that is, the isosceles triangle uses the radius of the curved edge 116 as its axis of symmetry. In some embodiments, the vertex of the isosceles triangle faces the curved edge 116. Facing the vertex outward can better conform to the curved edge 116 of the tray body 110 and facilitate stamping of the protrusion 114.

[0045] In some embodiments, the disc body 110 includes three groups of recessed and protruding combinations spaced apart along the circumference of the disc body 110, two of which are symmetrically distributed about the center of the circle, and another group of which is equidistant from the other two groups. It should be understood that the equidistant distance between another group of recessed and protruding combinations and the two groups of recessed and protruding combinations refers to the distance between the center of the protrusion 114 of the other group of recessed and protruding combinations closest to the arcuate edge 116 and the center of the protrusion 114 of the two groups of recessed and protruding combinations closest to the arcuate edge 116. Evenly distributing the recessed and protruding combinations along the circumference helps to effectively isolate the upper and lower positive current collector disc bodies 110, while also distributing the force applied by the upper positive current collector disc and reducing deformation of the protrusion 114.

[0046] In some embodiments, the number of the second holes 117 is three, and the positions of the three second holes 117 correspond to the positions of the three recess-protrusion combinations.

[0047] In some embodiments, the recessed portion 115 forms an inner cavity with an opening, and the outer surface of the protrusion 114 is curved. The length of the protrusion 114 along the surface of the disk body 110 is L5, and the length of the opening along the surface of the disk body 110 is L6, where L5 ≥ L6. Because the outer surface of the protrusion 114 is curved and its length is greater than or equal to the length of the opening, when the upper positive electrode current collecting disk is placed on the lower positive electrode current collecting disk, the opening of the upper recessed portion 115 abuts against the outer surface of the protrusion 114, creating a gap between the upper disk body 110 and the lower disk body 110, further reducing contact between the upper and lower disk bodies 110 and preventing overlap.

[0048] In some embodiments, the range of L5 is 0.3mm to 0.8mm. If the diameter of the protrusion 114 is too small, it is difficult to make a mold when producing the collecting disk, and it is difficult to form by stamping, which makes manufacturing difficult, has a low yield, takes a long time, and increases manufacturing costs. If the diameter of the protrusion 114 is too large, the area occupied by the disk surface becomes larger, which will inevitably occupy the welding area, reduce the welding area, reduce the welding current capacity, increase the welding temperature rise, and reduce the safety performance of the battery cell.

[0049] In some embodiments, the outer surface of the protrusion 114 and the inner surface of the recessed portion 115 are hemispherical in shape. During the processing of the protrusion 114 and the recessed portion 115, a mold is generally used to stamp the lower surface 113 of the positive electrode current collecting disk. The formation of the hemispherical protrusion 114 has low requirements for the mold. At the same time, the curved outer surface can also help reduce stress concentration compared to the right-angled outer surface, so that the protrusion 114 has better load-bearing capacity.

[0050] Example 2:

[0051] The difference between this embodiment and the first embodiment is that the protected subject is different. This embodiment is a cylindrical lithium battery including a positive electrode current collecting disk.

[0052] Specifically, the cylindrical lithium battery provided in this embodiment includes a positive electrode current collector disc, a housing, a cap, a winding core, and a negative electrode current collector disc provided in any of the aforementioned embodiments. The disc body 110 of the positive electrode current collector disc is connected to the winding core, and the tail of the positive electrode current collector disc is connected to the cap. It will be understood that when assembling the positive electrode current collector disc provided in Example 1 into a cylindrical lithium battery, the tail portion needs to be bent toward the center of the disc body 110.

[0053] Except for the above differences, other parts of this embodiment can refer to the first embodiment and will not be described in detail here.

[0054] Throughout this specification, reference to terms such as "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 that embodiment or example are included in at least one embodiment or example of the present embodiment. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0055] 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 these embodiments without departing from the principles and intent 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 collecting plate for a cylindrical lithium battery, characterized in that: The invention comprises a disk body (110) and a tail body (120) connected to each other, wherein the disk body (110) is used to connect to a winding core, and the tail body (120) is used to connect to a cap. The disk body (110) is provided with a first hole (111). The disk body (110) comprises an upper surface (112) and a lower surface (113) which are opposite to each other along the thickness direction of the disk body (110). The disk body (110) further comprises a protrusion (114) arranged on the upper surface (112) and a recessed portion (115) arranged on the lower surface (113) corresponding to the protrusion (114).

2. The positive electrode current collecting disk according to claim 1, characterized in that: The height of the protrusion (114) along the thickness direction of the disc body (110) is H1, the sum of the thickness of the disc body (110) and the height of the protrusion (114) along the thickness direction of the disc body (110) is H2, and 36%≤H1 / H2≤58%.

3. The positive electrode current collecting disk according to claim 1 or 2, characterized in that: The outer edge of the disk body (110) includes an arcuate edge (116), the radius of the arcuate edge (116) is R, the disk body (110) includes at least one protrusion (114) and at least one corresponding recess (115), the distance between the center of the protrusion (114) farthest from the center of the arcuate edge (116) and the center of the circle is L1, and 85%≤L1 / R≤95%.

4. The positive electrode current collecting disk according to claim 3, characterized in that: The disc body (110) further includes a second hole (117), the second hole (117) being located between the first hole (111) and the protrusion (114), the diameter of the second hole (117) being L2, the diameter of the first hole (111) being L3, and 25%≤L2 / L3≤35%.

5. The positive electrode current collecting disk according to claim 4, characterized in that: The disc body (110) further comprises at least one group of recessed and protruding combinations, wherein the recessed and protruding combinations comprise three protruding portions (114) and three corresponding recessed portions (115), and the line connecting the centers of the three protruding portions (114) forms an isosceles triangle.

6. The positive electrode current collecting disk according to claim 5, characterized in that: The base angle of the isosceles triangle is α, and 18°≤α≤37°.

7. The positive electrode current collecting disk according to claim 5, characterized in that: The perpendicular bisector on the base of the isosceles triangle overlaps with the radius of the arc-shaped edge (116), and the length of the base of the isosceles triangle is L4, 0.5 mm≤L4≤2 mm.

8. The positive electrode current collecting disk according to claim 5, characterized in that: The disc body (110) includes three groups of recessed and protruding combinations that are spaced apart and distributed in the circumferential direction of the disc body (110), wherein two groups of recessed and protruding combinations are symmetrically distributed with the center of the circle as the center, and the other group of recessed and protruding combinations are at the same distance from the two groups of recessed and protruding combinations.

9. The positive electrode current collecting disk according to claim 1, characterized in that: The recessed portion (115) forms an inner cavity with an opening, the outer surface of the protruding portion (114) is a curved surface, the length of the protruding portion (114) along the disk surface direction of the disk body (110) is L5, the length of the opening along the disk surface direction of the disk body (110) is L6, and L5≥L6.

10. A cylindrical lithium battery, characterized in that: The positive electrode current collecting disk comprises a positive electrode current collecting disk, a shell, a cap, a winding core and a negative electrode current collecting disk according to any one of claims 1 to 9, wherein the disk body (110) of the positive electrode current collecting disk is connected to the winding core, and the tail body (120) of the positive electrode current collecting disk is connected to the cap.

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