Winding core assembly and wound battery

Abstract

A winding core assembly including a positive electrode plate and a negative electrode plate, wherein a diaphragm is disposed between the positive electrode plate and the negative electrode plate, and wherein the winding core assembly has a central hole located at the winding center. The positive electrode plate has a leading edge at one end close to the central hole that has a sloping portion, and both longitudinal ends of the sloping portion are located on both widthwise edges of the positive electrode plate, or the leading edge has a convex or concave shape, and / or the negative electrode plate has a leading edge at one end close to the central hole that has a sloping portion, or the leading edge has a convex or concave shape. The sloping portion, the convex shape, and the concave shape each have a portion that is axially inclined with respect to the central hole. The inclined portion allows stress to be resolved along the circumferential direction of the electrode plate and the axial direction of the central hole. Because the outside of the winding core assembly is constrained by the casing, some of the stress in the axial direction of the central hole acts on the casing and is offset, and the remaining circumferential stress is small, making it less likely to cause problems such as deformation of the central hole, bending or wrinkling of the electrode plate, or even breakage.

Description

[Technical Field]

[0001] The present invention relates to the technical field of battery plate winding structures, and more particularly to a winding core assembly and a wound battery. [Background technology]

[0002] Lithium-ion batteries and sodium-ion batteries are two new types of rechargeable batteries with the advantages of high energy density, small volume structure, fast discharge rate, low self-discharge rate and long cycle time, etc., and are widely used in the fields of digital products, power battery systems and energy storage.

[0003] During the actual cycle of a lithium-ion battery, lithium ions are repeatedly inserted and extracted between the positive and negative electrodes. During the charging process, lithium ions are inserted into the negative electrode, causing it to expand, and during the discharging process, lithium ions are extracted from the negative electrode, causing it to shrink.

[0004] The expansion and contraction of the negative electrode generates stress in the plates. Because the outside of a cylindrical battery is constrained by a steel casing, the stress generated when the winding core expands and contracts continues to act on the inside of the battery cell, causing the center to deform and the plates to shift, leading to problems such as bending, wrinkling, and even breakage of the plates. Summary of the Invention

[0005] The present invention primarily solves the problem that the plates of the winding assembly are susceptible to stress caused by the expansion and contraction of the negative electrode, resulting in bending, wrinkling and even breakage of the plates.

[0006] According to one aspect of the present invention, one embodiment provides a winding core assembly including a positive electrode plate and a negative electrode plate. A diaphragm is disposed between the positive electrode plate and the negative electrode plate, and the winding core assembly has a central hole located at the center of winding. The positive electrode plate has a leading edge at one end near the central hole that has a sloped portion, and both longitudinal ends of the sloped portion are respectively located at both widthwise edges of the positive electrode plate, or the leading edge has a convex or concave shape. And / or, the tip edge portion of one end of the negative electrode plate near the central hole has an inclined portion, and both longitudinal ends of the inclined portion are respectively located on both widthwise edges of the negative electrode plate, or the tip edge portion has a convex or concave shape.

[0007] In some embodiments, the convex shape has an axisymmetric structure, and the axis of symmetry of the convex shape is located at the center in the width direction of the positive electrode plate or the negative electrode plate.

[0008] In some embodiments, the concave shape has an axisymmetric structure, and the axis of symmetry of the concave shape is located at the center in the width direction of the positive electrode plate or the negative electrode plate.

[0009] In some embodiments, the convex profile is an arc-shaped protrusion.

[0010] In some embodiments, the concave profile is an arc-shaped concave.

[0011] In some embodiments, both longitudinal ends of the inclined portion form an inclined angle with both widthwise edges of the positive electrode plate or the negative electrode plate.

[0012] In some embodiments, the number of turns that the sloped portion occupies on the positive electrode plate or the negative electrode plate is n, and 0.1≦n≦5.

[0013] In some embodiments, both longitudinal ends of the inclined portion are connected to both widthwise edge portions of the positive electrode plate or the negative electrode plate via curved portions, or both ends of the convex shape are connected to both widthwise edge portions of the positive electrode plate or the negative electrode plate via curved portions, or both ends of the concave shape are connected to both widthwise edge portions of the positive electrode plate or the negative electrode plate via curved portions.

[0014] In some embodiments, the diaphragm includes a first diaphragm and a second diaphragm, and the negative electrode plate, the first diaphragm, the positive electrode plate, and the second diaphragm are arranged in this order along a direction away from the central hole.

[0015] According to one aspect of the present invention, one embodiment provides a wound battery, the wound battery comprising: a core assembly according to any of the above-described embodiments; and a housing used to house the winding core assembly and filled with an electrolyte.

[0016] According to the winding core assembly and wound battery of the above-described embodiment, the positive electrode plate and / or the negative electrode plate are provided with an inclined portion, a convex shape, or a concave shape, and the inclined portion, the convex shape, and the concave shape all have a portion inclined in the axial direction relative to the center hole. When stress generated during expansion and contraction of the winding core acts on the inclined portion, the inclined portion can resolve the stress along the circumferential direction of the electrode plate and the axial direction of the center hole. Because the outside of the winding core assembly is restrained by the housing, some of the stress in the axial direction of the center hole acts on the housing and is offset, and the remaining circumferential stress is small, so problems such as deformation of the center hole, bending or wrinkling of the electrode plate, and even breakage are unlikely to occur. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic diagram of the three-dimensional structure of a winding core assembly according to the present invention; [Figure 2] FIG. 2 is a top view of the winding core assembly of the present invention. [Figure 3]1 is a schematic view of a winding core assembly according to the present invention, in which the leading edge of the electrode plate has a sloped portion; [Figure 4] 4 is a schematic diagram of a winding core assembly according to the present invention, in which the leading edge of the electrode plate is convex; FIG. [Figure 5] 4 is a schematic view of a winding core assembly according to the present invention, in which the leading edge of the electrode plate is concave; [Figure 6] 2 is a schematic view of an uncut leading edge of a plate of a winding core assembly of the present invention; FIG. [Figure 7] 4 is a schematic diagram of stress resolution of the inclined portion of the winding core assembly of the present invention after cutting the electrode plate; FIG. [Figure 8] 1 is a schematic diagram of a typical structural unit of a winding core assembly according to the present invention; [Figure 9] 2 is a schematic diagram of a winding method of the winding core assembly of the present invention; [Explanation of symbols]

[0018] 1 Positive electrode plate 2 negative electrode plates 3 center hole 4 First diaphragm 5 Second diaphragm 6 Tip side edge 61 Slope 62 Convex shape 63 Concave shape 7 Curved part DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention will be described in more detail below with reference to the drawings through specific embodiments. Similar components in different embodiments have the same associated component numbers. In the following embodiments, many detailed descriptions are provided to facilitate a better understanding of the present invention. However, those skilled in the art will readily recognize that some features may be omitted or replaced with other components, materials, or methods under different circumstances. Some operations related to the present invention may not be shown or described herein to avoid obscuring the core of the present invention with excessive explanation. However, those skilled in the art will be able to fully grasp the relevant operations without needing detailed descriptions of these related operations based on the descriptions in this specification and general knowledge in the art.

[0020] Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments, and the operational steps of each embodiment may be reordered or adjusted in a manner that would be obvious to one skilled in the art. Therefore, the specification and drawings are intended only to clearly explain the embodiments and do not imply any required configuration and / or order.

[0021] The numbering of parts in this specification, such as "first", "second", etc., is only for distinguishing the described items and does not have any order or technical meaning. "Connected" and "coupled" described in this invention include direct and indirect connection (coupling) unless otherwise stated.

[0022] As shown in Figures 1 and 2, a winding core assembly according to an embodiment of the present invention includes a positive electrode plate 1 and a negative electrode plate 2. A diaphragm is disposed between the positive electrode plate 1 and the negative electrode plate 2. The winding core assembly has a central hole 3 located at the center of the winding. The positive electrode plate 1 and the negative electrode plate 2 are collectively referred to as plates. Specifically, the winding core assembly may be constructed by sequentially stacking a diaphragm, a positive electrode plate 1, a diaphragm, and a negative electrode plate 2, and then winding the stack, with the center of the winding being the central hole 3.

[0023] The tip edge 6 at one end near the central hole 3 of the positive electrode plate 1 has an inclined portion 61, and both longitudinal ends of the inclined portion 61 are located on both widthwise edge portions of the positive electrode plate 1, or the tip edge 6 has a convex shape 62, or the tip edge 6 has a concave shape 63, and / or the tip edge 6 at one end near the central hole 3 of the negative electrode plate 2 has an inclined portion 61, and both longitudinal ends of the inclined portion 61 are located on both widthwise edge portions of the negative electrode plate 2, or the tip edge 6 has a convex shape 62, or the tip edge 6 has a concave shape 63.

[0024] The tip edge 6 at one end near the central hole 3 of the electrode plate has a sloping portion 61, and both longitudinal ends of the sloping portion 61 are located on both edges in the width direction of the negative electrode plate 2, which may be understood as the following two situations. As shown in FIG. 3 , the tip edge 6 is sloping as a whole. Alternatively, a portion of the tip edge 6 may be sloping. For example, only the middle portion of the tip edge 6 may be sloping, and the sloping portion 61 may occupy at least two-thirds of the tip edge 6.

[0025] The slope 61 may be a linear slope, a convex slope, a concave slope, or any combination of the above three slope types.

[0026] The tip edge 6 having a convex shape 62 may be understood as a part of the tip of one end close to the central hole 3 of the electrode plate protruding as shown in Fig. 4. The tip edge 6 having a concave shape 63 may be understood as a part of the tip of one end close to the central hole 3 of the electrode plate being recessed as shown in Fig. 5.

[0027] The inclined portion 61, the convex portion 62, and the concave portion 63 all have portions that are inclined in the axial direction relative to the center hole 3. As shown in Figure 6, when stress generated during expansion and contraction of the winding core acts on the inclined portions, the inclined portions can resolve the stress along the circumferential direction of the electrode plate and the axial direction of the center hole 3. The circumferential direction is the winding extension direction of the front edge portion 6 of the electrode plate. Because the outside of the winding core assembly is constrained by the casing, some of the stress in the axial direction of the center hole 3 acts on the casing, and the remaining circumferential stress is small. This reduces the risk of problems such as deformation of the center hole, bending, wrinkling, and even breakage of the electrode plate. Furthermore, the positive and negative electrode plates have high adhesion, making lithium deposition less likely to occur.

[0028] It should be understood that the leading edge 6 having the inclined portion 61, the leading edge 6 having the concave shape 63, and the leading edge 6 having the convex shape 62 are three selectable structural forms of the leading edge 6 of the electrode plate, and the specific leading edge 6 may be any one of the three. At least one of the positive electrode plate 1 and the negative electrode plate 2 has a leading edge 6 of any one of the above.

[0029] In some embodiments, as shown in Figure 4, the convex shape 62 has an axisymmetric structure, and the axis of symmetry of the convex shape 62 is located at the center in the width direction of the positive electrode plate 1 or the negative electrode plate 2. For example, the width direction of the electrode plate is the vertical direction in the figure, and the convex shape 62 has a vertically symmetric structure. The convex shape 62 has inclined portions on both sides of the axis of symmetry that can resolve stress in the axial direction of the central hole 3. With this arrangement, the stress received by the convex shape 62 of the electrode plate is distributed symmetrically, the electrode plate is less likely to shift position, the adhesion between the positive and negative electrode plates is improved, and lithium deposition is less likely to occur.

[0030] In some embodiments, as shown in Figure 5, the recessed shape 63 has an axisymmetric structure, and the axis of symmetry of the recessed shape 63 is located at the center in the width direction of the positive electrode plate 1 or the negative electrode plate 2. For example, the width direction of the electrode plate is the vertical direction in the figure, and the recessed shape 63 has a vertically symmetric structure. The recessed shape 63 has inclined portions on both sides of the axis of symmetry that can resolve stress in the axial direction of the central hole 3. With this arrangement, the stress received by the recessed shape 63 of the electrode plate is distributed symmetrically, the electrode plate is less likely to shift position, the adhesion between the positive and negative electrode plates is improved, and lithium deposition is less likely to occur.

[0031] In some embodiments, as shown in FIG. 4, the contour of the convex shape 62 may be an arc-shaped protrusion.

[0032] In other embodiments, the outer shape of the convex shape 62 may be a square protrusion.

[0033] In some embodiments, as shown in FIG. 5, the contour of the concave shape 63 may be an arc-shaped concave.

[0034] In other embodiments, the outer shape of the recessed shape 63 may be a rectangular recessed shape.

[0035] 1 to 3, both longitudinal ends of the inclined portion 61 form an inclined angle with the edges on both sides in the width direction of the positive electrode plate 1 or the negative electrode plate 2. That is, the tip edge 6 at one end near the center hole 3 of the electrode plate is inclined as a whole.

[0036] As shown in Figures 6 and 7, the inclined portion 61 may be formed by cutting the electrode plate. The inclined portion 61 allows stress F to be decomposed into a circumferential stress F1 and an axial stress F2 of the central hole 3. The axial stress F2 of the central hole 3 acts on the casing and is offset by the casing, while the circumferential stress F1 is smaller than the stress F and is distributed with a gradient on the inclined portion 61. This makes it less likely for deformation of the central hole 3 to occur, improves adhesion between the positive and negative electrode plates, and makes it less likely for lithium deposition to occur.

[0037] 1, the number of turns that the inclined portion 61 occupies on the positive electrode plate 1 or the negative electrode plate 2 is n, and 0.1≦n≦5. For example, n=1 indicates that the inclined portion 61 is provided on the first turn of the positive electrode plate 1 or the negative electrode plate 2 from the center hole 3.

[0038] In some embodiments, both longitudinal ends of the inclined portion 61 are connected via curved portions to both widthwise edge portions of the positive electrode plate 1 or the negative electrode plate 2. By providing the curved portions, it is possible to prevent sharp corners from being formed at both longitudinal ends of the inclined portion 61 of the electrode plate, making it less likely that the electrode plate will damage the diaphragm.

[0039] In some embodiments, both ends of the convex shape 62 are connected via curved portions to the edges on both sides in the width direction of the positive electrode plate 1 or the negative electrode plate 2. By providing the curved portions, it is possible to avoid the formation of sharp corners on both ends of the convex shape 62 of the electrode plate, and damage to the diaphragm by the electrode plate is less likely to occur.

[0040] 5, both ends of the recessed shape 63 are connected to the edges on both sides of the width of the positive electrode plate 1 or the negative electrode plate 2 via curved portions 7. By providing the curved portions 7, it is possible to prevent sharp corners from being formed on both ends of the electrode plate recessed shape 63, making it less likely that the electrode plate will damage the diaphragm.

[0041] In some embodiments, as shown in FIGS. 1 and 2 , the diaphragm includes a first diaphragm 4 and a second diaphragm 5, and the negative electrode plate 2, the first diaphragm 4, the positive electrode plate 1, and the second diaphragm 5 are arranged in this order in a direction away from the central hole 3. The positive electrode plate 1 has a leading edge 6 provided with an inclined portion 61. The inclined portion 61 may be formed by cutting the positive electrode plate 1. Cutting the positive electrode plate 1 not only reduces stress but also ensures that the lithium absorption capacity of the negative electrode plate 2 is greater than the lithium release capacity of the positive electrode plate 1, making lithium deposition less likely to occur.

[0042] Hereinafter, a wound battery according to an embodiment of the present invention will be described.

[0043] A wound battery according to an embodiment of the present invention includes the winding core assembly according to any of the above embodiments, and a housing used to house the winding core assembly and filled with an electrolyte.

[0044] The process of the electrode plates of the winding core assembly according to the present invention being displaced under stress will now be described.

[0045] Each layer of the winding core assembly (including the positive and negative electrode plate materials) can be assumed to be a macroscopic isotropic material, and a representative structural unit can be selected for analysis. The representative structural unit can be small enough to represent each component, or large enough to represent the winding core assembly, so the basic structure of the winding core assembly (diaphragm-negative electrode-diaphragm-positive electrode) is used as the representative unit. Figure 9 is a schematic diagram of the winding, and Figure 8 is a schematic diagram of a representative structural unit. A cylindrical coordinate system is used, with the axial direction being the z-axis and its length being 1. Edge effects are not taken into account.

[0046] The thickness of the winding of the winding core assembly is t, and the outer diameter after winding i turns is R i Let us take a point on the inside of the core where the radius is r, and assume that this point is located at the ith turn of the winding. That is, R i-1 ≦r <R i After n turns of winding, the circumferential stress at any point r in the winding core assembly is the winding tensile stress at point r and R i , R i+1 , ..., Rn winding tension T(R i ) and the circumferential stress distribution function at point r. That is,

number

[0047] The radial stress at an arbitrary point r in the winding core is calculated as follows:

number

[0048] During discharge, the negative electrode plate 2 contracts due to the release of lithium ions, and the positive electrode plate 1 is subjected to circumferential stress relative to the positive electrode plate 1 of the winding core. The direction of the circumferential stress is parallel to the electrode plate and moves away from the center of the circle, causing the positive electrode plate 1 to move in a direction away from the center of the circle.

[0049] During the charge / discharge cycle of the battery, the area around the central hole 3 of the winding core continues to expand and contract due to the insertion and extraction of lithium ions from the negative electrode plate 2, gradually loosening the positive electrode plate 1 and deforming the central hole 3 of the winding core. The distortion inside the winding core after winding and the displacement of the end face of the positive electrode plate 1 during the cycle of the winding core are as follows:

number

[0050] By cutting the inner ring (first winding) portion of the positive electrode plate 1 into a fixed shape, the stress on the positive electrode plate 1 due to the expansion and contraction of the winding core during the charge and discharge cycle of the battery can be uniformly distributed in the cut area of ​​the positive electrode plate 1 inside the winding core, and by forming a stress gradient in the cut area of ​​the positive electrode plate 1, the degree of loosening and misalignment of the positive electrode plate 1 inside the winding core can be reduced.

[0051] During charging, lithium ions are inserted into the negative electrode plate 2, causing it to expand, expanding the winding core. Because the exterior is constrained by the steel housing, stress on the winding core is concentrated only toward the center hole 3. The circumferential stress on the positive electrode plate 1 in the center hole 3 area is directed toward the center of the winding core. However, because the end face of the positive electrode plate 1 is inclined, this force can be resolved into a circumferential force F1 and a force F2 parallel to the winding core axis. Because both ends of the battery are constrained by the steel housing, the force F2 parallel to the winding core axis is counteracted by the steel housing. The movement of the positive electrode plate 1 is driven by the resolved force F1, but F1 is distributed linearly across the inclined end face of the positive electrode plate 1. Compared to the end face of the uncut positive electrode plate 1, F1 acting on the end face of the cut positive electrode plate 1 is smaller. This effectively alleviates the deformation problem around the center hole 3 of the winding core.

[0052] Although the present invention has been described in detail using specific examples, the above description is merely for the purpose of facilitating understanding of the present invention and is not intended to limit the present invention. Those skilled in the art to which the present invention pertains may make a number of simple deductions, modifications or substitutions based on the concept of the present invention.

Claims

1. a winding core assembly including a positive electrode plate and a negative electrode plate, a diaphragm being disposed between the positive electrode plate and the negative electrode plate, and the winding core assembly having a center hole located at a winding center; The tip edge of the positive electrode plate at one end near the central hole has an inclined portion, and both longitudinal ends of the inclined portion are respectively located on both widthwise edges of the positive electrode plate, or the tip edge has a convex or concave shape, and / or a tip edge portion at one end of the negative electrode plate close to the central hole has an inclined portion, and both longitudinal ends of the inclined portion are respectively located on both widthwise edges of the negative electrode plate, or the tip edge portion has a convex or concave shape.

2. 2. The winding core assembly according to claim 1, wherein the convex shape has an axisymmetric structure, and the axis of symmetry of the convex shape is located at the center in the width direction of the positive electrode plate or the negative electrode plate.

3. 2. The winding core assembly according to claim 1, wherein the concave shape has an axisymmetric structure, and the axis of symmetry of the concave shape is located at the center in the width direction of the positive electrode plate or the negative electrode plate.

4. 4. The winding core assembly according to claim 1, wherein the convex outer shape is an arc-shaped protrusion.

5. 4. The winding core assembly according to claim 1, wherein the outer shape of the concave portion is an arc-shaped concave portion.

6. The winding core assembly according to any one of claims 1 to 3, wherein both ends of the inclined portion in the longitudinal direction form an inclined angle with edges on both sides in the width direction of the positive electrode plate or the negative electrode plate.

7. 7. The winding core assembly according to claim 6, wherein the number of turns of the inclined portion on the positive electrode plate or the negative electrode plate is n, and 0.1≦n≦5.

8. 4. The winding core assembly according to claim 1, wherein both ends of the inclined portion in the longitudinal direction are connected to both edge portions of the positive electrode plate or the negative electrode plate in the width direction via curved portions; both ends of the convex shape are connected to both edge portions of the positive electrode plate or the negative electrode plate in the width direction via curved portions; and both ends of the concave shape are connected to both edge portions of the positive electrode plate or the negative electrode plate in the width direction via curved portions.

9. 4. The winding core assembly according to claim 1, wherein the diaphragm includes a first diaphragm and a second diaphragm, and the negative electrode plate, the first diaphragm, the positive electrode plate, and the second diaphragm are arranged in this order along a direction away from the central hole.

10. A wound battery, A winding core assembly according to any one of claims 1 to 9; a housing used to house the winding core assembly and filled with an electrolyte solution.

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