Roll core assembly and wound battery
By designing inclined sections, convex or concave sides of the pole end of the core assembly, the problem of the pole sheet bends, wrinkles or even fractures due to the expansion and contraction stress of the negative electrode, and the stress decomposition and the stability of the pole sheet are improved.
Patent Information
- Application Number
- CN202421425011.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-21
- Publication Date
- 2025-05-02
- Estimated Expiration
- 2034-06-21
AI Technical Summary
The pole sheet of the roll assembly is susceptible to the stress caused by the expansion and contraction of the negative electrode, and the pole sheet is bent, wrinkled and even broken.
A core roll assembly is designed, wherein a diaphragm is provided between the positive electrode sheet and the negative electrode sheet, and the end side of the electrode sheet has an inclined section, a convex side or a concave edge, and the inclined section, a convex side and a concave edge all have a portion axially inclined with respect to the central hole to decompose stress.
Through the design of inclined sections, convex sides and concave sides, stress can be decomposed along the annular direction of the pole sheet and the central hole axial direction, reducing the deformation of the central hole and the bending, wrinkling and even fracture of the pole sheet, and improving the fit and durability of the pole sheet.
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Figure CN222826449U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of battery pole piece winding structures, and in particular to a winding core assembly and a wound battery. Background Art
[0002] Lithium-ion batteries and sodium-ion batteries are two new types of rechargeable batteries with the advantages of high energy density, small volume, fast discharge rate, low self-discharge rate and long cycle. They are widely used in digital products, power battery systems and energy storage fields.
[0003] During the actual application cycle of lithium-ion batteries, lithium ions are repeatedly embedded and released between the positive and negative electrodes: during the charging process, lithium ions are embedded in the negative electrode, causing the negative electrode to expand; during the discharge process, lithium ions are released from the negative electrode, causing the negative electrode to shrink.
[0004] The expansion and contraction of the negative electrode will cause stress in the electrode. Since the cylindrical battery is bound by a steel shell on the outside, the stress generated by the expansion and contraction of the winding core will continuously act on the inside of the battery cell, causing the center to deform and the electrode to shift, resulting in problems such as bending, wrinkling, or even breaking of the electrode. Utility Model Content
[0005] The present application mainly solves the problem that the pole pieces of the winding assembly are easily affected by the stress generated by the expansion and contraction of the negative electrode, resulting in bending, wrinkling or even breaking of the pole pieces.
[0006] According to one aspect of the present application, an embodiment provides a winding core assembly, comprising a positive electrode sheet and a negative electrode sheet, wherein a separator is disposed between the positive electrode sheet and the negative electrode sheet, wherein the winding core assembly has a central hole located at the winding center, wherein the end of the positive electrode sheet close to one end of the central hole has an inclined section, wherein both ends of the inclined section in the length direction are respectively located at edges on both sides of the width direction of the positive electrode sheet, or the end side is a convex edge, or the end side is a concave edge,
[0007] And / or, the side edge of the end of the negative electrode plate close to one end of the center hole has an inclined section, and the two ends of the inclined section in the length direction are respectively located at the edges on both sides of the width direction of the negative electrode plate, or the side edge of the end is a convex edge, or the side edge of the end is a concave edge.
[0008] In some embodiments, the convex edge is an axisymmetric structure, and the axis of symmetry of the convex edge is located in the middle of the positive electrode sheet or the negative electrode sheet in the width direction.
[0009] In some embodiments, the concave edge is an axisymmetric structure, and the axis of symmetry of the concave edge is located in the middle of the positive electrode sheet or the negative electrode sheet in the width direction.
[0010] In some embodiments, the convex edge has an arc-shaped protrusion.
[0011] In some embodiments, the concave edge has an arc-shaped depression.
[0012] In some embodiments, both ends of the inclined segment in the length direction intersect with the edges of both sides of the positive electrode sheet or the negative electrode sheet in the width direction respectively.
[0013] In some embodiments, the number of turns of the positive electrode sheet or the negative electrode sheet occupied by the inclined segment is n, and 0.1≤n≤5.
[0014] In some embodiments, the two ends of the inclined segment in the length direction are connected to the edges on both sides of the width direction of the positive electrode sheet or the negative electrode sheet through rounded corners, or the two ends of the convex edge are connected to the edges on both sides of the width direction of the positive electrode sheet or the negative electrode sheet through rounded corners, or the two ends of the concave edge are connected to the edges on both sides of the width direction of the positive electrode sheet or the negative electrode sheet through rounded corners.
[0015] In some embodiments, the diaphragm includes a first diaphragm and a second diaphragm, and along a direction away from the central hole, the negative electrode plate, the first diaphragm, the positive electrode plate, and the second diaphragm are arranged in sequence.
[0016] According to one aspect of the present application, an embodiment provides a wound battery, including:
[0017] The winding core assembly as described in the above embodiment;
[0018] The shell is used to accommodate the winding core assembly, and the shell is provided with electrolyte.
[0019] According to the winding core assembly and wound battery of the above-mentioned embodiment, the positive electrode sheet and / or the negative electrode sheet are provided with an inclined section, a convex edge or a concave edge, and the inclined section, the convex edge and the concave edge all have a portion inclined relative to the axial direction of the center hole. When the stress generated by the expansion and contraction of the winding core acts on the inclined portion, the inclined portion can decompose the stress along the circumferential direction of the electrode sheet and the axial direction of the center hole. Since the outside of the winding core assembly is bounded by the shell, the axial stress component of the center hole can act on the shell to offset it, and the remaining circumferential stress component is small, and it is not easy to cause the problem of deformation of the center hole, bending, wrinkling or even fracture of the electrode sheet. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 It is a three-dimensional structural schematic diagram of the winding core assembly of the utility model.
[0021] Figure 2 It is a top view of the winding core assembly of the utility model.
[0022] Figure 3 It is a schematic diagram showing that the end side of the pole piece of the winding core assembly of the utility model has an inclined section.
[0023] Figure 4 This is a schematic diagram showing that the end side edge of the pole piece of the winding core assembly of the utility model is a convex edge.
[0024] Figure 5 This is a schematic diagram showing that the end side edge of the pole piece of the winding core assembly of the utility model is a concave edge.
[0025] Figure 6 It is a schematic diagram of the side edge of the pole piece of the winding core assembly of the utility model without cutting.
[0026] Figure 7 It is a schematic diagram of stress decomposition of the inclined part of the pole piece of the winding core assembly of the utility model after cutting.
[0027] Figure 8 It is a schematic diagram of a representative structural unit of the winding core assembly of the present invention.
[0028] Fig. 9 It is a schematic diagram of the winding method of the winding core assembly of the utility model.
[0029] Reference numerals:
[0030] 1. Positive electrode plate; 2. Negative electrode plate; 3. Center hole; 4. First diaphragm; 5. Second diaphragm; 6. Side edge of end; 61. Inclined section; 62. Convex edge; 63. Concave edge; 7. Rounded corner. DETAILED DESCRIPTION
[0031] The present application is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are intended to enable the present application to be better understood. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, and methods. In some cases, some operations related to the present application are not shown or described in the specification, in order to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations based on the description in the specification and the general technical knowledge in the art.
[0032] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations, and the operation steps involved in each embodiment can also be replaced or adjusted in a sequence in a manner that is obvious to those skilled in the art. Therefore, the specification and drawings are only for the purpose of clearly describing a certain embodiment and do not mean that the composition and / or sequence are necessary.
[0033] The serial numbers of the components in this document, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings).
[0034] like Figure 1 , Figure 2 As shown, the winding core assembly of the embodiment of the utility model includes a positive electrode sheet 1 and a negative electrode sheet 2, a separator is arranged between the positive electrode sheet 1 and the negative electrode sheet 2, and the winding core assembly has a central hole 3 located at the center of the winding. The positive electrode sheet 1 and the negative electrode sheet 2 are collectively referred to as the electrode sheet. Specifically, the winding core assembly can be composed of a separator, a positive electrode sheet 1, a separator, and a negative electrode sheet 2 stacked and wound in sequence, and the center of the winding is the central hole 3.
[0035] The end side edge 6 of the positive electrode sheet 1 near the center hole 3 has an inclined section 61, and the two ends of the inclined section 61 in the length direction are respectively located at the edges on both sides of the width direction of the positive electrode sheet 1, or the end side edge 6 is a convex edge 62, or the end side edge 6 is a concave edge 63. And / or, the end side edge 6 of the negative electrode sheet 2 near the center hole 3 has an inclined section 61, and the two ends of the inclined section 61 in the length direction are respectively located at the edges on both sides of the width direction of the negative electrode sheet 2, or the end side edge 6 is a convex edge 62, or the end side edge 6 is a concave edge 63.
[0036] The end side 6 of the electrode sheet near the center hole 3 has an inclined section 61, and the two ends of the inclined section 61 in the length direction are respectively located at the edges of the two sides in the width direction of the negative electrode sheet 2, which can be understood as the following two situations: Figure 3 As shown, the entire end side 6 is arranged inclined. A portion of the end side 6 is arranged inclined, for example, only the middle portion of the end side 6 is arranged inclined, and the inclined section 61 occupies at least two-thirds of the end side 6.
[0037] The inclined section 61 may be linearly inclined, convexly inclined, concavely inclined, or any combination of the above three inclined modes.
[0038] The end side 6 is a convex edge 62, which can be understood as: Figure 4 As shown in FIG. 1 , the end of the pole piece near the center hole 3 has a portion protruding. The side edge 6 of the end is a concave edge 63, which can be understood as follows: Figure 5 As shown, the end of the pole piece close to the center hole 3 is partially recessed.
[0039] The inclined section 61, the convex edge 62 and the concave edge 63 all have portions that are axially inclined relative to the central hole 3. Figure 6As shown, when the stress generated when the winding core expands and contracts acts on the inclined part, the inclined part can decompose the stress along the circumferential direction of the pole piece and the axial direction of the center hole 3. The circumferential direction is the winding extension direction of the end side edge 6 of the pole piece. Since the outside of the winding core assembly is bound by the shell, the axial component stress of the center hole 3 acts on the shell, and the remaining circumferential component stress is small. It is not easy to have problems such as deformation of the center hole, bending, wrinkling or even breakage of the pole piece. The positive and negative pole pieces have good fit and are not prone to lithium deposition.
[0040] It can be understood that the end side 6 is provided with an inclined section 61, the end side 6 is a concave edge 63, and the end side 6 is a convex edge 62, which are three optional structural forms of the end side 6 of the pole piece, and the specific end side 6 can be any one of the three. At least one of the positive pole piece 1 and the negative pole piece 2 has any of the above-mentioned end side 6.
[0041] In some embodiments, Figure 4 As shown, the convex edge 62 is an axisymmetric structure, and the symmetry axis of the convex edge 62 is located in the middle of the width direction of the positive electrode sheet 1 or the negative electrode sheet 2. For example, the width direction of the electrode sheet is the up-down direction in the figure, and the convex edge 62 is a vertically symmetrical structure. The convex edge 62 has inclined portions on both sides of the symmetry axis that can decompose the stress to the axial direction of the center hole 3. The above arrangement makes the stress on the convex edge 62 of the electrode sheet symmetrically arranged, the electrode sheet is not easy to deviate, the positive and negative electrode sheets 2 have good fit, and lithium precipitation is not easy to occur.
[0042] In some embodiments, Figure 5 As shown, the concave edge 63 is an axisymmetric structure, and the symmetry axis of the concave edge 63 is located in the middle of the width direction of the positive electrode sheet 1 or the negative electrode sheet 2. For example, the width direction of the electrode sheet is the up-down direction in the figure, and the concave edge 63 is a vertically symmetrical structure. The concave edge 63 has inclined portions on both sides of the symmetry axis that can decompose the stress to the axial direction of the center hole 3. The above arrangement makes the stress on the concave edge 63 of the electrode sheet symmetrically arranged, the electrode sheet is not easy to be offset, the positive and negative electrode sheets 2 have good fit, and lithium precipitation is not easy to occur.
[0043] In some embodiments, Figure 4 As shown, the outer shape of the convex edge 62 can be an arc-shaped convexity.
[0044] In other embodiments, the shape of the protruding edge 62 may also be an angular protrusion.
[0045] In some embodiments, Figure 5 As shown, the shape of the concave edge 63 can be an arc-shaped depression.
[0046] In other embodiments, the shape of the concave edge 63 may be an angular depression.
[0047] In some embodiments, Figure 1-3 As shown, the two ends of the inclined section 61 in the length direction intersect with the edges of the positive electrode sheet 1 or the negative electrode sheet 2 in the width direction, that is, the end side edge 6 of the electrode sheet close to the center hole 3 is arranged inclined as a whole.
[0048] like Figure 6 , 7 As shown, the inclined section 61 can be formed by cutting the pole piece. The inclined section 61 can decompose the stress F into the circumferential stress F1 and the axial stress F2 of the center hole 3. The axial stress F2 of the center hole 3 acts on the shell and is offset by the shell, the circumferential stress F1 is smaller than the stress F, and the circumferential stress F1 is distributed in a gradient on the inclined section 61, which is not easy to cause the center hole 3 to deform, the positive and negative pole pieces 2 have better fit, and lithium deposition is not easy to occur.
[0049] In some embodiments, Figure 1 As shown, the number of turns of the positive electrode sheet 1 or the negative electrode sheet 2 occupied by the inclined segment 61 is n, and 0.1≤n≤5. For example, n=1, indicating that starting from the center hole 3, the first turn of the positive electrode sheet 1 or the negative electrode sheet 2 is provided with the inclined segment 61.
[0050] In some embodiments, the two ends of the inclined section 61 in the length direction are connected to the edges of the positive electrode sheet 1 or the negative electrode sheet 2 in the width direction through rounded corners. The rounded corners can avoid forming sharp corners at the two ends of the inclined section 61 in the length direction, and the electrode sheet is not easy to damage the diaphragm.
[0051] In some embodiments, the two ends of the convex edge 62 are connected to the edges of the positive electrode sheet 1 or the negative electrode sheet 2 in the width direction through rounded corners. Providing rounded corners can avoid forming sharp corners at the two ends of the electrode convex edge 62, and the electrode is not easy to damage the diaphragm.
[0052] In some embodiments, Figure 5 As shown, the two ends of the concave edge 63 are connected to the edges of the positive electrode sheet 1 or the negative electrode sheet 2 in the width direction through fillets 7. The fillets 7 can prevent the two ends of the concave edge 63 of the electrode sheet from forming sharp corners, and the electrode sheet is not easy to damage the diaphragm.
[0053] In some embodiments, Figure 1 , Figure 2 As shown in FIG. , the diaphragm includes a first diaphragm 4 and a second diaphragm 5. In the direction away from the center hole 3, the negative electrode sheet 2, the first diaphragm 4, the positive electrode sheet 1, and the second diaphragm 5 are arranged in sequence. The end side 6 of the positive electrode sheet 1 is provided with an inclined section 61. The inclined section 61 can be formed by cutting the positive electrode sheet 1. Cutting the positive electrode sheet 1 can not only reduce stress, but also ensure that the lithium insertion capacity of the negative electrode sheet 2 is greater than the amount of lithium released from the positive electrode sheet 1, and the problem of lithium precipitation is not easy to occur.
[0054] The following describes a wound battery according to an embodiment of the present invention.
[0055] The wound battery of the embodiment of the utility model comprises a winding core assembly and a shell in any of the above embodiments. The shell is used to accommodate the winding core assembly, and an electrolyte is arranged in the shell.
[0056] The following describes the derivation process of the pole piece of the winding core assembly of the utility model being offset under stress.
[0057] Each layer of the core assembly (including the positive and negative electrode materials) is assumed to be a macroscopically isotropic material, and a representative structural unit can be taken for analysis. The representative structural unit can be small enough to represent each component and large enough to represent the core assembly, so the basic composition of the core assembly (diaphragm-negative electrode-diaphragm-positive electrode) is taken as the representative unit. Fig. 9 A winding diagram is given. Figure 8 A schematic diagram of a representative structural unit is given in . A cylindrical coordinate system is used, with the axial direction being the z axis, the length being 1, and the edge effect not being considered.
[0058] The thickness of the winding of the core assembly is t, and the outer diameter after winding i turns is R i , take a point at the radius r inside the winding core, assuming that this point is in the i-th winding circle, that is, R i-1 ≤r <R i After winding n turns, the hoop stress at any point r in the winding core assembly is equal to the winding tensile stress at point r plus R i , R i+1 , …, R n Multi-turn winding tension T(R i ) is the sum of the circumferential stress distribution functions at r, that is,
[0059]
[0060] The radial stress at any point r in the winding core can also be obtained:
[0061]
[0062] During discharge, the negative electrode sheet 2 shrinks due to the release of lithium ions, so that the positive electrode sheet 1 is subjected to the hoop stress of the winding core on the positive electrode sheet 1. The direction of the hoop stress is parallel to the sheet and away from the center of the circle, and the positive electrode sheet 1 will move away from the center of the circle.
[0063] During the battery charge and discharge cycle, the core center hole 3 area will expand and shrink due to the insertion and extraction of lithium ions from the negative electrode sheet 2, and the positive electrode sheet 1 will gradually relax, causing the core center hole 3 to deform. The strain in the core after winding and the displacement of the end face of the positive electrode sheet 1 during the core cycle are:
[0064]
[0065] Cutting the inner circle (the first winding circle) of the positive electrode sheet 1 into a certain shape can evenly disperse the stress on the positive electrode sheet 1 caused by the expansion and contraction of the winding core during the battery charge and discharge cycle to the cutting area of the positive electrode sheet 1 inside the winding core, forming a stress gradient in the cutting area of the positive electrode sheet 1, and reducing the degree of relaxation and deviation of the positive electrode sheet 1 inside the winding core.
[0066] When charging, lithium ions are embedded in the negative electrode sheet 2, and the negative electrode sheet 2 expands, causing the winding core to expand. At this time, the steel shell is restrained on the outside, and the stress of the winding core can only be concentrated in the direction of the center hole 3. The hoop stress of the positive electrode sheet 1 in the center hole 3 area points to the center of the winding core, but at this time, the end face of the positive electrode sheet 1 is an inclined surface, and the end face inclined surface of the positive electrode sheet 1 can decompose this force into a hoop force F1 and a force F2 parallel to the axis of the winding core. Since the two ends of the battery are restrained by the steel shell, the force F2 parallel to the axis of the winding core will be offset by the steel shell. The movement of the positive electrode sheet 1 is provided by the decomposed force F1, but at this time F1 is distributed in the inclined end face of the positive electrode sheet 1 in a linear gradient. Compared with the uncut end face of the positive electrode sheet 1, the end face F1 of the cut positive electrode sheet 1 is smaller. It can effectively alleviate the deformation problem of the center hole 3 of the winding core.
[0067] The above specific examples are used to illustrate the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the art of the present invention, some simple deductions, deformations or substitutions can be made based on the idea of the present invention.
Claims
1. A winding core assembly, characterized in that: The invention comprises a positive electrode sheet and a negative electrode sheet, wherein a separator is arranged between the positive electrode sheet and the negative electrode sheet, the winding core assembly has a central hole located at the winding center, and the side edge of the end of the positive electrode sheet close to one end of the central hole has an inclined section, and the two ends of the inclined section in the length direction are respectively located at the edges of the two sides of the width direction of the positive electrode sheet, or the side edge of the end head is a convex edge, or the side edge of the end head is a concave edge, And / or, the side edge of the end of the negative electrode plate close to one end of the center hole has an inclined section, and the two ends of the inclined section in the length direction are respectively located at the edges on both sides of the width direction of the negative electrode plate, or the side edge of the end is a convex edge, or the side edge of the end is a concave edge.
2. The winding core assembly according to claim 1, characterized in that: The convex edge is an axisymmetric structure, and the symmetry axis of the convex edge is located in the middle of the positive electrode sheet or the negative electrode sheet in the width direction.
3. The winding core assembly according to claim 1, characterized in that: The concave edge is an axisymmetric structure, and the symmetry axis of the concave edge is located in the middle of the positive electrode sheet or the negative electrode sheet in the width direction.
4. The winding core assembly according to any one of claims 1 to 3, characterized in that: The convex edge has an outer shape of an arc-shaped convexity.
5. The winding core assembly according to any one of claims 1 to 3, characterized in that: The shape of the concave edge is an arc-shaped depression.
6. The winding core assembly according to any one of claims 1 to 3, characterized in that: Both ends of the inclined section in the length direction intersect with the edges of both sides of the positive electrode sheet or the negative electrode sheet in the width direction respectively.
7. The winding core assembly according to claim 6, characterized in that: The number of turns of the positive electrode sheet or the negative electrode sheet occupied by the inclined section is n, and 0.1≤n≤5.
8. The winding core assembly according to any one of claims 1 to 3, characterized in that: The two ends of the inclined section in the length direction are connected to the edges on both sides of the width direction of the positive electrode sheet or the negative electrode sheet through rounded corners, or the two ends of the convex edge are connected to the edges on both sides of the width direction of the positive electrode sheet or the negative electrode sheet through rounded corners, or the two ends of the concave edge are connected to the edges on both sides of the width direction of the positive electrode sheet or the negative electrode sheet through rounded corners.
9. The winding core assembly according to any one of claims 1 to 3, characterized in that: The diaphragm includes a first diaphragm and a second diaphragm. Along a direction away from the central hole, the negative electrode sheet, the first diaphragm, the positive electrode sheet, and the second diaphragm are arranged in sequence.
10. A wound battery, characterized in that: include: The winding core assembly according to any one of claims 1 to 9; The shell is used to accommodate the winding core assembly, and the shell is provided with electrolyte.