Wound battery

Abstract

The invention belongs to the technical field of batteries, and discloses a winding type battery. The winding type battery comprises a negative plate, a positive plate and a diaphragm, a concave part is arranged in a corner area of the winding type battery and an inner side material area, facing the inside of the winding type battery, of the negative plate, the concave depth of each part of the concave part is equal, and the thickness of the inner side material area in the corner area is consistent except the concave part. The outer side material area, facing the outside of the winding type battery, of the negative plate is consistent in thickness in the corner area, and the inner side material area and the outer side material area are equal in thickness. The concave part is formed in the inner side material area of the negative plate, so that electrolyte infiltration of the inner side material area of the negative plate in the corner area is improved, an ion channel is enlarged, ion transmission resistance is reduced, impedance of the outer side material area is closer to that of the inner side material area, and the phenomena of lithium separation or black spots and the like of the winding type battery in the corner area are reduced. The thicknesses of the outer side material area and the inner side material area of the negative plate are uniform and consistent, the concave depths of the concave parts at all positions are equal, the preparation of the negative plate is easy to realize, and the production cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a wound battery. Background Art

[0002] With the rapid development of new energy technologies, batteries have been widely used in electronic equipment, electric vehicles, electric two-wheeled vehicles, power tools and other fields, and the requirements for battery quality and safety are becoming increasingly higher.

[0003] At present, wound lithium-ion batteries adopt a winding structure. At the bend of the pole piece of the wound lithium-ion battery, the inner and outer radii of the pole piece are different, resulting in the inner side of the pole piece being squeezed and the outer side being pulled. After the inner side is squeezed, the gap in the pole piece dressing area is small, the electrolyte infiltration is less, the ion channel is small, and the ion transmission is greatly obstructed; while after the outer side is pulled, the gap in the pole piece dressing area is large, the dressing is less, and the electron transmission is greatly obstructed. The final result is that the internal and external impedance of the pole piece is different, which easily causes lithium precipitation and black spots at the corners, affecting the performance of the lithium battery. Summary of the invention

[0004] The object of the present invention is to provide a wound battery with reduced impedance difference, uniform depression depth, easy control and low production cost.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] A wound battery, the wound battery comprising a negative electrode sheet, a positive electrode sheet and a separator, wherein at a corner area of ​​the wound battery, the negative electrode sheet is provided with a recessed portion facing an inner material area within the wound battery, the recessed depths of the recessed portion are equal at all locations, and except for the recessed portion, the thickness of the inner material area in the corner area is consistent, the thickness of the outer material area of ​​the negative electrode sheet facing the outside of the wound battery is consistent in the corner area, and the inner material area and the outer material area are of equal thickness.

[0007] As an optional embodiment of the above-mentioned wound battery, the negative electrode sheet is wound along its length direction, the recessed portion is in a long strip shape, and the length direction of the recessed portion extends along the width direction of the negative electrode sheet.

[0008] As an optional embodiment of the above-mentioned wound battery, the recessed portion includes a through section, and the through section extends along the width direction of the negative electrode sheet and penetrates through both ends of the negative electrode sheet.

[0009] As an optional embodiment of the above-mentioned wound battery, the recessed portion includes a plurality of partitioning segments, and the plurality of partitioning segments are arranged at intervals along the width direction of the negative electrode sheet.

[0010] As an optional embodiment of the above-mentioned wound battery, in the corner area of ​​the wound battery, a plurality of the recessed portions are provided on any layer of the negative electrode sheet, and the recessed portions are spaced apart and distributed along the winding direction.

[0011] As an optional embodiment of the above-mentioned wound battery, on any layer of the negative electrode sheet, the recessed portions are distributed at equal intervals along the winding direction.

[0012] As an optional embodiment of the above-mentioned wound battery, on any layer of the negative electrode sheet, the depression depths of the depressions are equal.

[0013] As an optional embodiment of the above-mentioned wound battery, the recessed portion is provided on each layer of the negative electrode sheet.

[0014] As an optional embodiment of the above-mentioned wound battery, the recessed parts on each layer of the negative electrode sheets have the same depth.

[0015] As an optional embodiment of the above-mentioned wound battery, the recessed portion is formed by laser etching.

[0016] Beneficial effects of the present invention:

[0017] The wound battery provided by the present invention has a uniform thickness of the inner material area and the outer material area in the corner area of ​​the wound battery, except for the recessed portion, and the inner material area and the outer material area are of equal thickness. In the corner area of ​​the wound battery, a recessed portion is formed on the inner material area of ​​the negative electrode sheet, thereby improving the electrolyte infiltration of the inner material area of ​​the negative electrode sheet in the corner area, increasing the ion channel, reducing the ion transmission resistance, and making the impedance of the outer material area and the inner material area more similar, thereby reducing the occurrence of lithium deposition or black spots in the corner area of ​​the wound battery. Moreover, except for the recessed portion, the thickness of the outer material area and the inner material area of ​​the negative electrode sheet is uniform and consistent, and the recessed depth of the recessed portion is equal at various locations. The preparation of the negative electrode sheet is easy to achieve, no other special treatment is required, it is easy to control, and the production cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of a wound battery provided in an embodiment of the present invention;

[0019] Figure 2 is a schematic structural diagram of a negative electrode sheet provided in one embodiment of the present invention;

[0020] Figure 3 is a schematic cross-sectional view of a recessed portion provided by an embodiment of the present invention;

[0021] Figure 4 It is a schematic diagram of the structure of a negative electrode sheet provided in another embodiment of the present invention.

[0022] In the figure:

[0023] 1. diaphragm; 2. positive electrode sheet; 3. negative electrode sheet; 4. recessed portion; 41. through section; 42. separation section. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0025] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0027] In the description of this embodiment, the terms "upper", "lower", "right", etc., directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0028] like Figure 1As shown, this embodiment provides a wound battery. Specifically, the wound battery includes a negative electrode sheet 3, a positive electrode sheet 2 and a separator 1. In the corner area of ​​the wound battery, the negative electrode sheet 3 is provided with a recessed portion 4 facing the inner material area inside the wound battery, and the recessed depth of the recessed portion 4 is equal at all places. Except for the recessed portion 4, the thickness of the inner material area in the corner area is consistent. The thickness of the outer material area of ​​the negative electrode sheet 3 facing the outside of the wound battery is consistent in the corner area, that is, the recessed portion 4 only exists in the inner material area of ​​the negative electrode sheet 3. Moreover, the inner material area and the outer material area are of equal thickness.

[0029] The wound battery provided in this embodiment has a uniform thickness of the inner material area and the outer material area in the corner area of ​​the wound battery, except for the recessed portion 4, and the inner material area and the outer material area are of equal thickness. In the corner area of ​​the wound battery, by forming a recessed portion 4 on the inner material area of ​​the negative electrode sheet 3, the electrolyte infiltration of the inner material area of ​​the negative electrode sheet 3 in the corner area is improved, the ion channel is increased, the ion transmission resistance is reduced, and the impedance of the outer material area and the inner material area is made closer, thereby reducing the occurrence of lithium precipitation or black spots in the corner area of ​​the wound battery. Moreover, except for the recessed portion 4, the thickness of the outer material area and the inner material area of ​​the negative electrode sheet 3 is uniform and consistent, and the recessed depth of the recessed portion 4 is equal at various locations. The preparation of the negative electrode sheet 3 is easy to achieve, no other special treatment is required, it is easy to control, and the production cost is low.

[0030] The specific winding structure of the wound battery is not limited. For example, Figure 1 As shown, the negative electrode sheet 3 is placed outside and the positive electrode sheet 2 is placed inside, the negative electrode sheet 3 and the positive electrode sheet 2 are separated by a separator 1, and the wound battery is formed by winding with a winding device. In other embodiments, the positive electrode sheet 2 is placed outside and the negative electrode sheet 3 is placed inside, the positive electrode sheet 2 and the negative electrode sheet 3 are separated by a separator 1, and the wound battery can also be formed by winding.

[0031] The number of windings of the wound battery in this embodiment is not limited, and can be 2, 3 or more. For example, the following description is made by taking a wound battery with 4 windings as an example.

[0032] The wound battery provided in this embodiment can be a lithium battery, a sodium battery, a nickel-hydrogen battery, a lead-acid battery, etc.

[0033] like Figure 1 , Figure 2 and Figure 4As shown, optionally, the negative electrode sheet 3 is wound along its length direction, and the recessed portion 4 is in the shape of an elongated strip, and the length direction of the recessed portion 4 extends along the width direction of the negative electrode sheet 3. That is to say, the elongated recessed portion 4 is formed on the inner material area of ​​the negative electrode sheet 3 along a direction perpendicular to the winding direction of the negative electrode sheet 3, so that the impedance of the inner material area of ​​the negative electrode sheet 3 can be adjusted in the width direction of the negative electrode sheet 3, which is conducive to improving the consistency of the wound battery in the width direction of the negative electrode sheet 3. The length of the recessed portion 4 is approximately the same as the width of the negative electrode sheet 3. The width of the recessed portion 4 is determined according to the radius of the corner area. In this embodiment, the width of the recessed portion 4 is between 0.2 mm and 1 mm, and can be 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm or 1 mm, etc.

[0034] In one embodiment, Figure 2 As shown, the recessed portion 4 includes a through section 41, which extends along the width direction of the negative electrode sheet 3 and penetrates both ends of the negative electrode sheet 3. Specifically, one recessed portion 4 includes a linear through section 41, which extends from one end of the negative electrode sheet 3 in the width direction to the other end of the negative electrode sheet 3, which is conducive to achieving uniform impedance adjustment. Figure 3 As shown, the cross-section of the through section 41 is in the shape of a regular groove, so as to keep the depth of the recessed portion 4 consistent at all locations.

[0035] In another embodiment, Figure 4 As shown, the recessed portion 4 includes a plurality of partitions 42, which are arranged at intervals along the width direction of the negative electrode sheet 3, and the partitions 42 extend along the width direction of the negative electrode sheet 3. The partitions 42 are separated from each other, which is conducive to storing electrolyte, thereby reducing ionic impedance and improving the life of the wound battery. For example, Figure 4 As shown, one recessed portion 4 includes three partitions 42, all of which are in the shape of line segments, and the lengths of the partitions 42 may be equal or unequal. In other embodiments, the partitions 42 may also be in the shape of spots.

[0036] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, optionally, in the corner area of ​​the wound battery, a plurality of such recessed portions 4 are provided on any layer of the negative electrode sheet 3, and the recessed portions 4 are spaced apart along the winding direction. The plurality of recessed portions 4 are spaced apart along the winding direction, which is conducive to adjusting the impedance of the negative electrode sheet 3 in sections through the recessed portions 4 in the winding direction. Figure 2 As shown, three corner regions of the negative electrode sheet 3 are shown, and each corner region has four parallel recessed portions 4 that are spaced apart and distributed along the length direction of the negative electrode sheet 3 .

[0037] Optionally, in the corner area of ​​the wound battery, on any layer of the negative electrode sheet 3, each of the recessed portions 4 is equally spaced along the winding direction. Equally spaced distribution is conducive to improving the uniformity of impedance distribution in the winding direction. Optionally, the spacing size is not less than 1 mm, which is convenient for process control and large-scale production. Furthermore, the spacing size is not greater than 4 mm, and the spacing size can be adjusted within the range of 1 mm to 4 mm according to the size of the corner area of ​​the wound battery. When the radius of the corner area is large, the spacing size selects a larger value, such as 3.5 mm. When the radius of the corner area is small, the spacing size selects a smaller value, such as 1.2 mm.

[0038] Optionally, in the corner area of ​​the wound battery, on any layer of the negative electrode sheet 3, the depth of each recessed portion 4 is equal. On the one hand, it is easier to prepare the negative electrode sheet 3 and process the recessed portion 4, easy to control, and low in production cost. On the other hand, the impedance characteristics of the same layer at different positions are the same, and the performance consistency of the wound battery in the same layer is good.

[0039] like Figure 1 As shown, optionally, the recessed portion 4 is provided in the corner area of ​​each layer of the negative electrode sheet 3. Thus, the negative electrode impedance of each layer of the corner area is optimized, and the lithium deposition phenomenon of the wound battery is reduced.

[0040] Optionally, the recessed portion 4 on each layer of the negative electrode sheet 3 has the same depth. On the one hand, it is easier to prepare the negative electrode sheet 3 and process the recessed portion 4, which is easy to control and has low production cost. On the other hand, the impedance characteristics of different layers in the corner area are the same, and the performance consistency of the wound battery at different layers is good.

[0041] Optionally, the recessed portion 4 is formed by laser etching. In this embodiment, the above-mentioned recessed portions 4 on the negative electrode sheet 3 are formed by a laser scribing and etching process. Specifically, a laser generator generates a high-energy laser beam, which is focused and collimated by an optical system and then irradiated onto the surface of the negative electrode material area. After the negative electrode material absorbs the energy of the laser, the surface temperature rises rapidly to reach a melting point or boiling point, thereby melting, vaporizing or decomposing the negative electrode material to form a scribed or etched recessed portion 4. Laser scribing and etching is a processing method that uses laser technology to accurately scribing and etching materials, and has the advantages of high precision, high speed and non-contact.

[0042] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A wound battery, characterized in that: The wound battery comprises a negative electrode sheet (3), a positive electrode sheet (2) and a separator (1); in a corner area of ​​the wound battery, the negative electrode sheet (3) is provided with a recessed portion (4) facing an inner material area inside the wound battery; the recessed portion (4) has the same depth at all locations; except for the recessed portion (4), the thickness of the inner material area in the corner area is consistent; the thickness of the outer material area of ​​the negative electrode sheet (3) facing the outside of the wound battery is consistent in the corner area; and the inner material area and the outer material area are of equal thickness.

2. The wound battery according to claim 1, characterized in that: The negative electrode sheet (3) is wound along its length direction, the recessed portion (4) is in a long strip shape, and the length direction of the recessed portion (4) extends along the width direction of the negative electrode sheet (3).

3. The wound battery according to claim 2, characterized in that: The recessed portion (4) comprises a through section (41), wherein the through section (41) extends along the width direction of the negative electrode sheet (3) and penetrates through both ends of the negative electrode sheet (3).

4. The wound battery according to claim 2, characterized in that: The recessed portion (4) comprises a plurality of partition segments (42), and the plurality of partition segments (42) are arranged at intervals along the width direction of the negative electrode sheet (3).

5. The wound battery according to claim 2, characterized in that: In the corner area of ​​the wound battery, a plurality of recessed portions (4) are provided on any layer of the negative electrode sheet (3), and the recessed portions (4) are distributed at intervals along the winding direction.

6. The wound battery according to claim 5, characterized in that: On any layer of the negative electrode sheet (3), the recessed portions (4) are distributed at equal intervals along the winding direction.

7. The wound battery according to claim 5, characterized in that: On any layer of the negative electrode sheet (3), the recessed depths of the recessed portions (4) are equal.

8. The wound battery according to claim 1, characterized in that: The recessed portion (4) is provided on each layer of the negative electrode sheet (3).

9. The wound battery according to claim 8, characterized in that: The recessed parts (4) on the negative electrode sheets (3) of each layer have the same recessed depth.

10. The wound battery according to any one of claims 1 to 9, characterized in that: The recessed portion (4) is formed by laser etching.

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