Roll core structure and secondary battery

Abstract

The utility model provides a roll core structure and a secondary battery. The roll core structure comprises a positive plate, a first diaphragm, a negative plate and a second diaphragm which are stacked and wound, and a first straight area, a first R-angle area, a second straight area and a second R-angle area which are sequentially connected end to end are formed on the roll core structure; the positive plate comprises a positive head part, a double-sided paste-coated foil part, a single-sided paste-coated foil part and a positive tail part which are sequentially connected along the winding direction, and the positive tail part is positioned on the outer side of the tail part of the negative plate; the connection junction of the double-sided paste-coated foil part and the single-sided paste-coated foil part is a first connection junction, the first connection junction is located in the first R angle area, and the first positive electrode adhesive layer is attached to the outer side of the part, close to the first connection junction, of the single-sided paste-coated foil part.

Description

Technical Field

[0001] The present disclosure relates to the field of winding core technology, and in particular to a winding core structure and a secondary battery. Background Art

[0002] For battery cell models with narrower widths, such as battery cells with a width of less than 20 mm, the width of the corresponding straight area of ​​the battery cell is also smaller, so that the single-sided and double-sided junction of the positive electrode paste, i.e., the starting and ending positions of the glue coating, and the distance between the positive ear position, i.e., the offset distance, are smaller, usually within 5 mm. Prior art, such as a pole piece and a lithium-ion battery disclosed in a Chinese patent with application number CN202120442429.1, has adhesive tape attached to the head and tail of the positive electrode sheet, but because the edge of the PET high-temperature adhesive tape attached to the end position of the positive electrode paste is sharp, and the end position of the positive electrode paste is a single-sided paste, i.e., a dislocated structure, the positive electrode sheet is easily cut off under high pressure formation, especially at the position corresponding to the positive ear, so that in the subsequent cycle, the pole sheet has a serious problem of pole sheet fragmentation due to expansion and contraction. For the lithium battery cell with reverse roll structure, some designs extend the adhesive tape at the positive electrode fragment to cover the positive electrode paste length, but this design reduces the energy density of the battery cell and cannot completely solve the fragmentation problem. Utility Model Content

[0003] The purpose of the present disclosure is to overcome the deficiencies in the prior art and to provide a winding core structure and a secondary battery that prevents electrode breakage and improves winding core yield.

[0004] The purpose of this disclosure is achieved through the following technical solutions:

[0005] A winding core structure, comprising:

[0006] A positive electrode sheet, a first separator, a negative electrode sheet and a second separator are stacked and wound, the winding core structure is formed with a first straight area, a first R angle area, a second straight area and a second R angle area connected end to end in sequence, the positive electrode sheet includes a positive electrode head, a double-sided pasted foil part, a single-sided pasted foil part and a positive electrode tail connected in sequence along the winding direction, the positive electrode tail is located outside the tail of the negative electrode sheet, the winding core structure also includes a positive electrode ear and a negative electrode ear, the positive electrode ear is welded to the positive electrode tail in the second straight area, and the negative electrode ear is welded to the tail of the negative electrode sheet in the second straight area,

[0007] The winding core structure also includes a first positive electrode adhesive layer, and the connection junction between the double-sided pasted foil portion and the single-sided pasted foil portion is a first connection junction, and the first connection junction is located in the first R corner area. The first positive electrode adhesive layer is attached to the outer side of the portion of the single-sided pasted foil portion adjacent to the first connection junction, one end of the first positive electrode adhesive layer extends to the double-sided pasted foil portion, and the other end of the first positive electrode adhesive layer extends to the second R corner area.

[0008] In one embodiment, the winding core structure also includes a second positive electrode adhesive layer, and the connection junction between the single-sided pasted foil portion and the positive electrode tail is the second connection junction, the second connection junction is located in the first R corner area, the second positive electrode adhesive layer is attached to the inner side of the second connection junction, one end of the second positive electrode adhesive layer extends to the single-sided pasted foil portion, and the other end of the second positive electrode adhesive layer extends to the second R corner area.

[0009] In one embodiment, the length of the second positive electrode adhesive layer is greater than the length of the first positive electrode adhesive layer.

[0010] In one of the embodiments, the winding core structure further includes a third positive electrode adhesive layer, the third positive electrode adhesive layer is attached to the outer side of the second connection junction, and the third positive electrode adhesive layer extends from the first R corner area to the second R corner area.

[0011] In one of the embodiments, the winding core structure further includes a negative electrode adhesive layer, which is respectively attached to two side surfaces of the tail of the negative electrode sheet, and the negative electrode adhesive layer extends from the first R corner area to the second straight area.

[0012] In one embodiment, the thickness of the positive electrode sheet is 100um-105um.

[0013] In one embodiment, the thickness of the negative electrode sheet is 120um-125um.

[0014] In one embodiment, the thickness of the first diaphragm is 7um-10um.

[0015] A secondary battery comprises the roll core structure described in any one of the above embodiments.

[0016] Compared with the prior art, the present invention has at least the following advantages:

[0017] The above-mentioned core structure is formed with a first straight area, a first R-angle area, a second straight area and a second R-angle area which are connected end to end in sequence. The positive electrode sheet is provided with a positive electrode head, a double-sided pasted foil portion, a single-sided pasted foil portion and a positive electrode tail along the winding direction. The connection junction between the double-sided pasted foil portion and the single-sided pasted foil portion is the first connection junction, and the first connection junction is located in the first R-angle area. The first positive electrode adhesive layer is attached to the outer side of the single-sided pasted foil portion adjacent to the first connection junction, that is, the position of the first connection junction in the traditional core is adjusted from the straight area to the R-angle area. The R-angle area has a smaller expansion stress when the core is formed, thereby avoiding the problem of electrode sheet breakage caused by thickness difference at the first connection when the straight area is formed, thereby improving the yield of the core. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 This is a schematic structural diagram of a winding core structure according to an embodiment;

[0020] Figure 2 for Figure 1 Another structural schematic diagram of the winding core structure shown;

[0021] Figure 3 for Figure 1 Schematic diagram of the structure of the positive electrode sheet with a core structure shown. DETAILED DESCRIPTION

[0022] In order to facilitate the understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are given in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thoroughly and comprehensively understood.

[0023] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present disclosure. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0025] The present disclosure provides a winding core structure, including a positive electrode sheet, a first separator, a negative electrode sheet and a second separator stacked and wound, the winding core structure is formed with a first straight area, a first R angle area, a second straight area and a second R angle area connected end to end in sequence, the positive electrode sheet includes a positive electrode head, a double-sided paste foil part, a single-sided paste foil part and a positive electrode tail connected in sequence along the winding direction, the positive electrode tail is located outside the tail of the negative electrode sheet, the winding core structure also includes a positive electrode ear and a negative electrode ear, the positive electrode ear is welded to the positive electrode tail in the second straight area , the negative electrode ear is welded to the tail of the negative electrode sheet in the second straight area; the core structure also includes a first positive electrode adhesive layer, the connection junction between the double-sided pasted foil part and the single-sided pasted foil part is a first connection junction, the first connection junction is located in the first R corner area, the first positive electrode adhesive layer is attached to the outer side of the portion of the single-sided pasted foil part adjacent to the first connection junction, one end of the first positive electrode adhesive layer extends to the double-sided pasted foil part, and the other end of the first positive electrode adhesive layer extends to the second R corner area.

[0026] The above-mentioned core structure is formed with a first straight area, a first R-angle area, a second straight area and a second R-angle area which are connected end to end in sequence. The positive electrode sheet is provided with a positive electrode head, a double-sided pasted foil portion, a single-sided pasted foil portion and a positive electrode tail along the winding direction. The connection junction between the double-sided pasted foil portion and the single-sided pasted foil portion is the first connection junction, and the first connection junction is located in the first R-angle area. The first positive electrode adhesive layer is attached to the outer side of the single-sided pasted foil portion adjacent to the first connection junction, that is, the position of the first connection junction in the traditional core is adjusted from the straight area to the R-angle area. The R-angle area has a smaller expansion stress when the core is formed, thereby avoiding the problem of electrode sheet breakage caused by thickness difference at the first connection when the straight area is formed, thereby improving the yield of the core.

[0027] In order to better understand the technical solutions and beneficial effects of the present invention, the present invention is further described in detail below in conjunction with specific embodiments:

[0028] like Figures 1 to 3As shown, a winding core structure 10 of an embodiment includes a positive electrode sheet 100, a first separator 200, a negative electrode sheet 300 and a second separator 400 which are stacked and wound. The winding core structure 10 is formed with a first straight area 10a, a first R-angle area 10b, a second straight area 10c and a second R-angle area 10d which are connected end to end in sequence. The positive electrode sheet 100 includes a positive electrode head 110, a double-sided pasted foil part 120, a single-sided pasted foil part 130 and a positive electrode tail 140 which are connected in sequence along the winding direction. The positive electrode tail 140 is located outside the tail of the negative electrode sheet 300. The winding core structure 10 also includes a positive electrode ear 400 and a negative electrode ear 500. The positive electrode ear 400 is welded to the positive electrode tail 140 in the second straight area 10c, and the negative electrode ear 500 is welded to the tail of the negative electrode sheet 300 in the second straight area 10c.

[0029] Furthermore, the winding core structure 10 also includes a first positive electrode adhesive layer 600, and the connection junction between the double-sided pasted foil portion 120 and the single-sided pasted foil portion 130 is a first connection junction 120a, and the first connection junction 120a is located in the first R corner area 10b, and the first positive electrode adhesive layer 600 is attached to the outer side of the portion of the single-sided pasted foil portion 130 adjacent to the first connection junction 120a, and one end of the first positive electrode adhesive layer 600 extends to the double-sided pasted foil portion 120, and the other end of the first positive electrode adhesive layer 600 extends to the second R corner area 10d.

[0030] In the present embodiment, the connection junction of the double-sided pasted foil portion 120 and the single-sided pasted foil portion 130 is the first connection junction 120a, the double-sided pasted foil portion 120 is pasted on both sides, that is, coated with active materials, and the single-sided pasted foil portion 130 is pasted on one side, so that there is a thickness difference between the double-sided pasted foil portion 120 and the single-sided pasted foil portion 130. If the first connection junction 120a is set in the straight area, the expansion stress in the straight area is large during formation, and there is a risk that the thickness difference between the double-sided pasted foil portion 120 and the single-sided pasted foil portion 130 will cause the positive electrode sheet 100 to break. However, the present application sets the first connection junction 120a in the R corner area, and the expansion stress in the R corner area is small during formation, so as to avoid the problem of broken pieces caused by the thickness difference during formation. Furthermore, the first positive electrode adhesive layer 600 is attached to the outer side of the portion of the single-sided paste-coated foil portion 130 adjacent to the first connection junction 120a to achieve insulation and fixing effects. In this embodiment, the first positive electrode adhesive layer 600 is PET high temperature adhesive tape.

[0031] The winding core structure 10 is formed with a first straight area 10a, a first R angle area 10b, a second straight area 10c and a second R angle area 10d connected in sequence, and the positive electrode sheet 100 is provided with a positive electrode head 110, a double-sided pasted foil part 120, a single-sided pasted foil part 130 and a positive electrode tail 140 along the winding direction, and the connection junction between the double-sided pasted foil part 120 and the single-sided pasted foil part 130 is a first connection junction 120a, and the first connection junction 120d is a second connection junction 120c. A connection junction 120a is located in the first R-angle area 10b, and the first positive electrode adhesive layer 600 is attached to the outer side of the single-sided paste-coated foil portion 130 adjacent to the first connection junction 120a, that is, the position of the first connection junction 120a in the traditional winding core is adjusted from the straight area to the R-angle area. The R-angle area has a smaller expansion stress when the winding core is formed. In this way, the problem of electrode breakage caused by thickness difference at the first connection when the straight area is formed is avoided, thereby improving the yield of the winding core.

[0032] like Figure 1 and Figure 2 As shown, in one embodiment, the roll core structure 10 also includes a second positive electrode adhesive layer 700, and the connection junction between the single-sided pasted foil portion 130 and the positive electrode tail portion 140 is a second connection junction 130a, and the second connection junction 130a is located in the first R corner area 10b, and the second positive electrode adhesive layer 700 is attached to the inner side of the second connection junction 130a, and one end of the second positive electrode adhesive layer 700 extends to the single-sided pasted foil portion 130, and the other end of the second positive electrode adhesive layer 700 extends to the second R corner area 10d. It can be understood that the inner side of the single-sided paste foil portion 130 is coated with active material, while the positive electrode tail 140 is not coated with active material, that is, there is a thickness difference between the single-sided paste foil portion 130 and the positive electrode tail 140, and the second connection junction 130a is set in the first R corner area 10b. The first R corner area 10b has a small expansion stress during formation, which avoids the problem of the positive electrode sheet 100 breaking due to the thickness difference at the second connection junction 130a. Further, the second positive electrode adhesive layer 700 is attached to the positive electrode tail 140 to achieve the effect of fixing and insulation. In this embodiment, the second positive electrode adhesive layer 700 is PET high-temperature adhesive tape.

[0033] In one embodiment, the length of the second positive electrode adhesive layer 700 is greater than the length of the first positive electrode adhesive layer 600. It can be understood that the first positive electrode adhesive layer 600 is attached to the single-sided paste-coated foil portion 130, the second positive electrode adhesive layer 700 is attached to the positive electrode tail 140, the first positive electrode adhesive layer 600 is located in the inner circle of the positive electrode sheet 100 after winding, and the second positive electrode adhesive layer 700 is located in the outer circle of the positive electrode sheet 100 after winding, so that the length of the second positive electrode adhesive layer 700 is greater than the length of the first positive electrode adhesive layer 600.

[0034] like Figure 1 and Figure 2 As shown, in one embodiment, the winding core structure 10 further includes a third positive electrode adhesive layer 800, and the third positive electrode adhesive layer 800 is attached to the outside of the second connection junction 130a, and the third positive electrode adhesive layer 800 extends from the first R corner area 10b to the second R corner area 10d. It can be understood that the third positive electrode adhesive layer 800 is attached to the outside of the second connection junction 130a, that is, the second positive electrode adhesive layer 700 and the third positive electrode adhesive layer 800 are respectively attached to the two sides of the positive tail 140 to achieve insulation and fixing effects. In this embodiment, the third positive electrode adhesive layer 800 is PET high temperature adhesive tape.

[0035] like Figure 1 and Figure 2 As shown, in one embodiment, the winding core structure 10 also includes a negative electrode adhesive layer 900, and the negative electrode adhesive layer 900 is respectively attached to the two side surfaces of the tail of the negative electrode sheet 300, and the negative electrode adhesive layer 900 extends from the first R corner area 10b to the second straight area 10c to insulate the tail of the negative electrode sheet 300 from the positive electrode tail 140, and at the same time play a fixing effect.

[0036] In one embodiment, the thickness of the positive electrode sheet 100 is 100um-105um. In this embodiment, the thickness of the positive electrode sheet 100 is 103um. Further, the thickness of the paste on the positive electrode sheet 100 is 710mm-770mm, and the two sides of the positive electrode sheet 100 are the positive electrode A side and the positive electrode B side, respectively. The positive electrode A side is a side close to the negative electrode sheet 300, and the positive electrode B side is a side away from the negative electrode sheet 300. The thickness of the paste on the positive electrode A side is 766mm, and the thickness of the paste on the positive electrode B side is 714mm.

[0037] In one embodiment, the thickness of the negative electrode sheet 300 is 120um-125um. In this embodiment, the thickness of the negative electrode sheet 300 is 123um. Further, the thickness of the paste on the negative electrode sheet 300 is 725mm-770mm, and the two sides of the negative electrode sheet 300 are the negative electrode A side and the negative electrode B side, respectively. The negative electrode A side is the side away from the positive electrode sheet 100, and the negative electrode B side is the side close to the positive electrode sheet 100. The thickness of the paste on the negative electrode A side is 765mm, and the thickness of the paste on the negative electrode B side is 729mm.

[0038] In one embodiment, the thickness of the first separator 200 is 7um-10um. In this embodiment, the thickness of the first separator 200 is 9um. Furthermore, the thickness of the second separator 400 is also 9um. The first separator 200 and the second separator 400 respectively separate the wound positive electrode sheet 100 and the negative electrode sheet 300 to insulate and allow ions of the positive and negative electrode sheets 300 to pass through.

[0039] The present application also provides a secondary battery, comprising the winding core structure 10 described in any one of the above embodiments.

[0040] Compared with the prior art, the present invention has at least the following advantages:

[0041] The winding core structure 10 is formed with a first straight area 10a, a first R angle area 10b, a second straight area 10c and a second R angle area 10d connected in sequence, and the positive electrode sheet 100 is provided with a positive electrode head 110, a double-sided pasted foil part 120, a single-sided pasted foil part 130 and a positive electrode tail 140 along the winding direction, and the connection junction between the double-sided pasted foil part 120 and the single-sided pasted foil part 130 is a first connection junction 120a, and the first connection junction 120d is a second connection junction 120c. A connection junction 120a is located in the first R-angle area 10b, and the first positive electrode adhesive layer 600 is attached to the outer side of the single-sided paste-coated foil portion 130 adjacent to the first connection junction 120a, that is, the position of the first connection junction 120a in the traditional winding core is adjusted from the straight area to the R-angle area. The R-angle area has a smaller expansion stress when the winding core is formed. In this way, the problem of electrode breakage caused by thickness difference at the first connection when the straight area is formed is avoided, thereby improving the yield of the winding core.

[0042] The above-mentioned embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the utility model patent. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the patent of the present disclosure shall be based on the attached claims.

Claims

1. A winding core structure, comprising a positive electrode sheet, a first separator, a negative electrode sheet and a second separator stacked and wound, the winding core structure forming a first straight area, a first R angle area, a second straight area and a second R angle area connected end to end in sequence, the positive electrode sheet comprises a positive electrode head, a double-sided pasted foil portion, a single-sided pasted foil portion and a positive electrode tail connected in sequence along the winding direction, the positive electrode tail is located outside the tail of the negative electrode sheet, the winding core structure also includes a positive electrode ear and a negative electrode ear, the positive electrode ear is welded to the positive electrode tail in the second straight area, and the negative electrode ear is welded to the tail of the negative electrode sheet in the second straight area, characterized in that The winding core structure also includes a first positive electrode adhesive layer, and the connection junction between the double-sided pasted foil portion and the single-sided pasted foil portion is a first connection junction, and the first connection junction is located in the first R corner area. The first positive electrode adhesive layer is attached to the outer side of the portion of the single-sided pasted foil portion adjacent to the first connection junction, one end of the first positive electrode adhesive layer extends to the double-sided pasted foil portion, and the other end of the first positive electrode adhesive layer extends to the second R corner area.

2. The winding core structure according to claim 1, characterized in that: The winding core structure also includes a second positive electrode adhesive layer, and the connection junction between the single-sided pasted foil portion and the positive electrode tail is the second connection junction, the second connection junction is located in the first R corner area, the second positive electrode adhesive layer is attached to the inner side of the second connection junction, one end of the second positive electrode adhesive layer extends to the single-sided pasted foil portion, and the other end of the second positive electrode adhesive layer extends to the second R corner area.

3. The winding core structure according to claim 2, characterized in that: The length of the second positive electrode adhesive layer is greater than the length of the first positive electrode adhesive layer.

4. The winding core structure according to claim 2, characterized in that: The winding core structure also includes a third positive electrode adhesive layer, which is attached to the outer side of the second connection junction, and the third positive electrode adhesive layer extends from the first R corner area to the second R corner area.

5. The winding core structure according to claim 1, characterized in that: The winding core structure also includes a negative electrode adhesive layer, which is respectively attached to two side surfaces of the tail of the negative electrode sheet, and the negative electrode adhesive layer extends from the first R corner area to the second straight area.

6. The winding core structure according to claim 1, characterized in that: The thickness of the positive electrode sheet is 100um-105um.

7. The winding core structure according to claim 1, characterized in that: The thickness of the negative electrode sheet is 120um-125um.

8. The winding core structure according to claim 1, characterized in that: The thickness of the first diaphragm is 7um-10um.

9. A secondary battery, characterized in that: The invention comprises the winding core structure according to any one of claims 1 to 8.

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