Winding battery cell and battery

Abstract

The winding cell comprises a positive plate and a negative plate, the positive plate comprises a first positive straight section located at the winding starting end, the first positive straight section is provided with a filling layer and a positive coating which are sequentially arranged in the winding direction from the winding starting end to the winding tail end, and the first positive straight section is provided with a second positive straight section located at the winding starting end. The positive electrode coating is provided with a positive electrode starting end along the winding direction; the negative plate comprises a first negative straight section adjacent to the first positive straight section, the first negative straight section is provided with a negative coating, and the negative coating is provided with a negative starting end in the winding direction; wherein the negative starting end exceeds the positive starting end in the opposite direction of the winding direction, an interval space is formed between the negative starting end and the positive starting end, and at least part of the filling layer is located in the interval space. And the filling layer supports the negative electrode coating in the interval space, and the negative electrode coating is not easy to drop powder, so that the production yield of the winding battery cell is higher, and the cycle safety performance of the battery is better. The utility model is applied to the field of energy storage elements.

Description

Technical Field

[0001] The utility model relates to the field of energy storage elements, in particular to a wound battery cell and a battery. Background Art

[0002] In recent years, due to the demand for digital, mobile communications and other products, the market demand for batteries has been growing, especially the pursuit of larger capacity and lower impedance batteries of the same size to meet the product's requirements for high energy density and low power consumption. However, in the cell structure of conventional batteries, in order to ensure sufficient overhang area (the area where the negative electrode sheet exceeds the positive electrode sheet in order to meet the requirement of the negative electrode sheet covering the positive electrode sheet), the positive electrode head needs to be cut. In related technologies, in order to compensate for the height difference caused by cutting, the single-sided area of ​​the negative electrode head is generally extended over the corner and folded, but the negative electrode folded section is prone to powder loss after hot pressing, resulting in poor battery K value, cycle lithium deposition and other abnormalities, affecting the battery's yield and battery cycle safety performance. Utility Model Content

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a wound battery cell that can improve the yield rate and battery cycle safety performance.

[0004] A battery having the wound battery cell is also provided.

[0005] The wound battery cell according to the first embodiment of the present invention includes:

[0006] A positive electrode sheet comprising a first positive straight section located at a winding start end, the first positive straight section having a filling layer and a positive electrode coating sequentially arranged along a winding direction from the winding start end to the winding end end, the positive electrode coating having a positive electrode start end along the winding direction;

[0007] a negative electrode sheet comprising a first negative electrode straight section adjacent to the first positive electrode straight section, the first negative electrode straight section having a negative electrode coating, the negative electrode coating having a negative electrode starting end along the winding direction;

[0008] The negative electrode start end exceeds the positive electrode start end in the opposite direction of the winding direction, and a gap is formed between the negative electrode start end and the positive electrode start end, and at least a part of the filling layer is located in the gap.

[0009] The wound battery cell according to the embodiment of the first aspect of the present invention has at least the following beneficial effects: the filling layer supports the negative electrode coating in the spacing space, and when the wound battery cell is hot-pressed, the negative electrode coating abuts against the filling layer, and the negative electrode coating is not easy to fall off, so that the production yield of the wound battery cell is higher and the battery cycle safety performance is better.

[0010] According to some embodiments of the present invention, the distance between the filling start end of the filling layer along the winding direction and the negative electrode start end is X, and the wound battery cell is configured as: X=±2mm.

[0011] According to some embodiments of the present invention, the filling start is aligned with the negative electrode start.

[0012] According to some embodiments of the present invention, the distance between the starting end of the positive electrode and the starting end of the negative electrode is Y, and the wound battery cell is configured such that: Y≥3mm.

[0013] According to some embodiments of the present invention, the thickness of the filling layer is h, the thickness of the positive electrode coating is H, and the wound battery cell is configured as follows: 0.9H≤h≤1.1H.

[0014] According to some embodiments of the present invention, the filling layer is a coating layer or an adhesive paper layer.

[0015] According to some embodiments of the present invention, the positive electrode sheet further includes a positive electrode current collector and a positive electrode tab connected to the positive electrode current collector, the positive electrode current collector having a first connection position, and the negative electrode sheet further includes a negative electrode current collector and a negative electrode tab connected to the negative electrode current collector, the negative electrode current collector having a second connection position;

[0016] Among them, the surface perpendicular to the thickness direction of the wound battery cell is defined as the projection surface, the first connection position forms a first projection on the projection surface, the second connection position forms a second projection on the projection surface, and the filling layer forms a third projection on the projection surface, and the first projection and the second projection are both located outside the third projection.

[0017] According to some embodiments of the present invention, the wound battery cell also includes a wound diaphragm, and the diaphragm includes a first clamping section and a first diaphragm straight section arranged in sequence along the winding direction, the first diaphragm straight section is used to separate the first positive electrode straight section and the first negative electrode straight section, and the first clamping section is used to be clamped by a clamping plate.

[0018] According to some embodiments of the present invention, the negative electrode sheet further includes a second clamping segment, wherein the second clamping segment and the first negative electrode straight segment are sequentially arranged along the winding direction, the second clamping segment is used to be clamped by a clamping plate, and the second clamping segment is formed by a negative electrode current collector.

[0019] A battery according to an embodiment of the second aspect of the present invention includes:

[0020] shell;

[0021] The wound battery cell described in the first embodiment is arranged inside the shell.

[0022] The battery according to the embodiment of the second aspect of the present utility model has at least the following beneficial effects: the use of the wound battery cell in the embodiment of the first aspect can improve the production yield and battery cycle safety performance.

[0023] Additional aspects and advantages of the present invention will be given in part in the following description and will become apparent from the following description or learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0025] Figure 1 Schematic diagram of the end face structure of a wound battery cell in the related art;

[0026] Figure 2 This is a schematic diagram of the end face structure of a wound battery cell according to an embodiment of the present invention.

[0027] Figure Number:

[0028] Positive electrode sheet 100; first positive electrode straight section 110; positive electrode coating 111; filling layer 112; positive electrode start 113; filling start 114;

[0029] Negative electrode sheet 200; first negative electrode straight section 210; negative electrode coating 211; negative electrode starting end 212; spacing space 213;

[0030] Diaphragm 300; first clamping section 310; first diaphragm straight section 320. DETAILED DESCRIPTION

[0031] The following describes in detail embodiments of the present invention. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0032] In the description of the present invention, it should be understood that descriptions involving orientation, such as the orientation or positional relationship indicated by up, down, etc., are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0033] In the description of this utility model, "a number" refers to one or more, and "a plurality" refers to two or more. The use of "first" or "second" is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of the indicated technical features, or implicitly indicating the order of the indicated technical features.

[0034] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0035] Battery cells include wound cells and laminated cells. The manufacturing process of wound cells is mature, and the manufacturing efficiency of wound cells is higher than that of laminated cells. They are widely used in the battery field. Among them, wound cells include square wound cells and cylindrical wound cells. Square wound cells are mostly used in rectangular square batteries or soft-pack batteries, while cylindrical wound cells are mostly used in cylindrical batteries. Square wound cells include a straight portion and two arc portions connected to opposite sides of the straight portion. The cylindrical wound cell is cylindrical in shape as a whole.

[0036] During the production process of wound battery cells, the positive electrode sheet, negative electrode sheet and separator of the wound battery cell are first aligned and stacked into a stack, and then wound from one end of the stack, which is the starting end of the winding. When winding, you first need to clamp the part at one end of the stack, and then wind it with the clamped part as the winding center.

[0037] In the related art, refer to Figure 1As shown, the clamping part includes the negative electrode sheet 200 and the separator 300. During winding, after the clamping part is turned over once or multiple times, the positive electrode sheet 100 begins to be wound together with the negative electrode sheet 200 and the separator 300. The starting winding part of the positive electrode sheet 100 is generally located within the straight part, and in order to improve the energy density of the positive electrode sheet 100, the positive electrode sheet 100 is generally coated with paint. After winding, one end of the positive electrode sheet 100 is close to the arc part; and in order to ensure sufficient overhang area (in order to meet the requirements of the negative electrode sheet 200), the positive electrode sheet 100 is wound together with the negative electrode sheet 200 and the separator 300. The coating of the negative electrode sheet 200 needs to cover the coating of the positive electrode sheet 100 along the winding direction. The end of the positive electrode sheet 100 needs to be close to the arc portion to improve energy density, but it needs to be spaced apart from the arc portion to ensure sufficient overhang area, that is, safety performance. Therefore, the end of the positive electrode sheet 100 is generally set to maintain an appropriate distance from the arc portion, but at this time, a gap 213 is formed at the missing position of the positive electrode sheet 100. In the subsequent hot pressing process of the straight portion, the existence of the gap 213 causes the negative electrode coating 211 corresponding to the gap 213 to easily fall off, resulting in a poor battery K value, abnormalities such as lithium deposition during cycling, and affecting the battery's yield and battery cycle safety performance.

[0038] Reference Figure 2 As shown, the first embodiment of the present invention provides a wound battery cell, including: a positive electrode sheet 100 and a negative electrode sheet 200.

[0039] The positive electrode sheet 100 includes a first positive straight segment 110 located at the beginning of the winding process. The portion of the positive electrode sheet 100 located in the straight portion of the wound battery cell forms the positive straight segment, while the portion of the positive electrode sheet 100 located at the center of the winding process and initially wound constitutes the first positive straight segment 110 of the multiple positive straight segments. The first positive straight segment 110 includes a positive current collector, a positive coating 111 coated on the surface of the positive current collector, and a filling layer 112. The filling layer 112 and the positive coating 111 are sequentially arranged along the winding direction from the beginning to the end of the winding process. The positive coating 111 has a positive starting end 113 along the winding direction. The positive starting end 113 is the end of the positive coating 111 located at the beginning of the winding process.

[0040] The negative electrode sheet 200 includes a first negative straight section 210 adjacent to the first positive straight section 110. The portion of the negative electrode sheet 200 located in the straight portion of the wound battery cell forms the negative straight section. The first negative straight section 210 is positioned adjacent to the first positive straight section 110 to facilitate ion exchange between the first negative straight section 210 and the first positive straight section 110, thereby enabling battery charging and discharging. The first negative straight section 210 includes a negative current collector and a negative coating 211 coated on the surface of the negative current collector. The negative coating 211 has a negative electrode starting end 212 along the winding direction. The negative electrode starting end 212 is the end of the negative electrode coating 211 located at the beginning of the winding.

[0041] The negative electrode start 212 extends beyond the positive electrode start 113 in the direction opposite to the winding direction, forming a gap 213 between the negative electrode coating 211 and the positive electrode coating 111 along the winding direction. This meets the design requirements of the overhang zone and, in turn, the battery safety requirements. At least a portion of the filling layer 112 is located within the gap 213, supporting the negative electrode coating 211 within the gap 213. During hot pressing of the wound cell, the negative electrode coating 211 abuts the filling layer 112, preventing the negative electrode coating 211 from shedding powder. This results in a higher production yield for the wound cell and improved battery cycle safety.

[0042] In this embodiment, the positive electrode current collector is aluminum foil, and the positive electrode coating 111 can be made of materials such as lithium cobalt oxide, lithium iron phosphate, lithium manganese oxide, ternary materials such as lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide, or a sodium ion material. The negative electrode current collector is copper foil, and the negative electrode coating 211 can be made of materials such as graphite-based materials, silicon-based materials, and lithium titanate negative electrode materials. The filling layer 112 can be a coating, such as an oxide primer, including but not limited to oxides such as aluminum oxide, magnesium oxide, zirconium oxide, and quartz. The filling layer 112 can also be a tape layer, including but not limited to high-viscosity green tape, high-temperature yellow tape, and foam tape.

[0043] In some specific embodiments of the present invention, the distance between the filling start end 114 of the filling layer 112 and the negative electrode start end 212 along the winding direction is X, and the wound battery cell is configured as: X=±2 mm.

[0044] It should be noted that manufacturing errors are inevitable during the winding process, resulting in a gap between the formed filling layer 112 and the negative electrode start 212. In this embodiment, the filling start 114 of the filling layer 112 extends beyond the negative electrode start by at most 2122 mm. In other words, the filling layer 112 extends beyond the negative electrode start by at most 2122 mm in the first positive electrode straight section 110. Alternatively, the filling start 114 of the filling layer 112 is at most shorter than the negative electrode start by at most 2122 mm. In other words, the filling layer 112 is at most shorter than the negative electrode start by at most 2122 mm in the first positive electrode straight section 110.

[0045] Reference Figure 2 As shown, in some specific embodiments of the present invention, the filling start end 114 is aligned with the negative electrode start end 212 .

[0046] It is worth understanding that when the filling start 114 is exactly aligned with the negative electrode start 212, the filling layer 112 can not only fully support the negative electrode start 212, thereby improving the yield rate of battery cell production and battery cycle performance, but also ensure that there is sufficient overhang area between the positive electrode coating 111 and the negative electrode coating 211, thereby ensuring the safety performance of the battery.

[0047] It should be noted that the filling start end 114 being aligned with the negative electrode start end 212 means that: X≈0, and the distance between the negative electrode start end 212 and the filling start end 114 is basically negligible. In addition, it is more preferable that the filling start end 114 is equal to or slightly beyond the negative electrode start end 212.

[0048] Reference Figure 1 and Figure 2 As shown, in some specific embodiments of the present invention, the distance between the positive electrode starting end 113 and the negative electrode starting end 212 is Y, and the wound battery cell is configured such that: Y≥3 mm.

[0049] It is worth noting that the length of the overhang region between the positive electrode start end 113 and the negative electrode start end 212 along the winding direction is Y. When Y ≥ 3 mm, the safety performance of the battery is better.

[0050] Reference Figure 2 As shown, in some specific embodiments of the present invention, the thickness of the filling layer 112 is h, the thickness of the positive electrode coating 111 is H, and the wound battery cell is configured as follows: 0.9H≤h≤1.1H.

[0051] It is worth understanding that the thickness of the filling layer 112 is basically the same as the thickness of the positive electrode coating 111, and the filling layer 112 can completely fill the gap 213 between the positive electrode starting end 113 and the negative electrode starting end 212, that is, completely fill the overhang area, so that the thickness of the filling layer 112 will not be too low, and the filling layer 112 has a better support effect on the negative electrode coating 211, and the thickness of the filling layer 112 will not be too thick, and the filling layer 112 will not affect the fit between the positive electrode coating 111 and the negative electrode coating 211.

[0052] Reference Figure 2 As shown, in some specific embodiments of the present invention, the positive electrode sheet 100 further includes a positive electrode current collector and a positive electrode ear connected to the positive electrode current collector ( Figure 2 The positive electrode current collector has a first connection position, and the negative electrode sheet 200 further includes a negative electrode current collector and a negative electrode ear connected to the negative electrode current collector ( Figure 2In the black coating area away from the center), the negative electrode current collector has a second connection position; wherein, a surface perpendicular to the thickness direction of the wound battery cell is defined as a projection surface, the first connection position forms a first projection on the projection surface, the second connection position forms a second projection on the projection surface, and the filling layer 112 forms a third projection on the projection surface, and both the first projection and the second projection are located outside the third projection.

[0053] It is worth understanding that the first connection position of the positive electrode ear, the second connection position of the negative electrode ear and the position of the filling layer 112 are staggered in sequence along the direction of the line connecting the two arc portions, so that the first connection position, the second connection position and the filling layer 112 will not overlap along the thickness direction of the wound battery cell, thereby avoiding affecting the winding flatness of the battery cell.

[0054] In this embodiment, the positive electrode tab is a separate tab. A positive electrode tab region not coated with the positive electrode coating 111 is reserved on the surface of the positive electrode current collector. This region serves as the first connection location. The positive electrode tab is welded to the surface of the positive electrode current collector to achieve electrical connection between the positive electrode tab and the positive electrode current collector. The negative electrode tab is a separate tab. A negative electrode tab region not coated with the negative electrode coating 211 is reserved on the surface of the negative electrode current collector. This region serves as the first connection location. The negative electrode tab is welded to the surface of the negative electrode current collector to achieve electrical connection between the negative electrode tab and the negative electrode current collector.

[0055] Reference Figure 2 As shown, in some specific embodiments of the present invention, the wound battery cell also includes a wound diaphragm 300, and the diaphragm 300 includes a first clamping section 310 and a first diaphragm straight section 320 arranged in sequence along the winding direction. The first diaphragm straight section 320 is used to separate the first positive electrode straight section 110 and the first negative electrode straight section 210, and the first clamping section 310 is used to be clamped by the clamping plate.

[0056] It is worth noting that the first clamping section 310 is formed by the separator 300 to be clamped by the clamping plate in the winding process and wound to form a wound battery cell. The design of the negative electrode current collector or the negative electrode current collector and the negative electrode coating 211 in the first clamping section 310 is eliminated. First, the length of the negative electrode current collector is saved, saving costs. Second, the negative electrode sheet 200 is directly aligned with the positive electrode sheet 100. The negative electrode sheet 200 is not affected by the deformation and displacement during the winding process of the first clamping section 310, and the relative position accuracy of the negative electrode sheet 200 and the positive electrode sheet 100 is higher. Finally, the first clamping section 310 does not have the negative electrode coating 211, and there is no powder falling in the first clamping section 310. In addition, there is no influence of the thickness of the negative electrode current collector and the negative electrode coating 211 in the first clamping section 310, and the winding flatness of the wound battery cell is higher.

[0057] In some specific embodiments of the present invention, the negative electrode sheet 200 further includes a second clamping section. The second clamping section and the first negative electrode straight section 210 are sequentially arranged along the winding direction. The second clamping section is used to be clamped by the clamping plate. The second clamping section is formed by the negative electrode current collector.

[0058] It's worth noting that the separator 300 and the negative electrode current collector can also form a second clamping section, with the clamping plates in the winding process directly clamping the separator 300 and the negative electrode current collector, and winding them to form a wound battery cell. Eliminating the negative electrode coating 211 in the second clamping section saves negative electrode material and reduces material costs. Without the negative electrode coating 211 in the second clamping section, powder shedding in the second clamping section is eliminated. Furthermore, the thickness of the negative electrode current collector and negative electrode coating 211 are not affected in the second clamping section, resulting in a higher winding smoothness of the wound battery cell.

[0059] The second embodiment of the present invention provides a battery comprising: a housing; and a wound battery cell according to the first embodiment, the wound battery cell being disposed within the housing. It is worth noting that the use of the wound battery cell according to the first embodiment can improve production yield and battery cycle safety.

[0060] In this embodiment, the outer shell can be a hard shell or a soft shell. When the outer shell is a hard shell, the outer shell is generally square, that is, the battery is a square battery; when the outer shell is a soft shell, the outer shell is generally square pouch-shaped, that is, the battery is a soft pack battery. The outer shell can be made of a hard aluminum shell, a hard steel shell, a soft aluminum-plastic film, etc.

[0061] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A wound battery cell, characterized in that: include: A positive electrode sheet comprising a first positive straight section located at a winding start end, the first positive straight section having a filling layer and a positive electrode coating sequentially arranged along a winding direction from the winding start end to the winding end end, the positive electrode coating having a positive electrode start end along the winding direction; a negative electrode sheet comprising a first negative electrode straight section adjacent to the first positive electrode straight section, the first negative electrode straight section having a negative electrode coating, the negative electrode coating having a negative electrode starting end along the winding direction; The negative electrode start end exceeds the positive electrode start end in the opposite direction of the winding direction, and a gap is formed between the negative electrode start end and the positive electrode start end, and at least a part of the filling layer is located in the gap.

2. The wound battery cell according to claim 1, wherein: The distance between the filling start end of the filling layer along the winding direction and the negative electrode start end is X, and the wound battery cell is configured as follows: X=±2 mm.

3. The wound battery cell according to claim 2, characterized in that: The filling start end is aligned with the negative electrode start end.

4. The wound battery cell according to claim 1, wherein: The distance between the starting end of the positive electrode and the starting end of the negative electrode is Y, and the wound battery core is configured such that: Y≥3mm.

5. The wound battery cell according to claim 1, wherein: The thickness of the filling layer is h, the thickness of the positive electrode coating is H, and the wound battery cell is configured as follows: 0.9H≤h≤1.1H.

6. The wound battery cell according to claim 1, wherein: The filling layer is a coating layer or a tape layer.

7. The wound battery cell according to claim 1, characterized in that: The positive electrode sheet further includes a positive electrode current collector and a positive electrode tab connected to the positive electrode current collector, wherein the positive electrode current collector has a first connection position; the negative electrode sheet further includes a negative electrode current collector and a negative electrode tab connected to the negative electrode current collector, wherein the negative electrode current collector has a second connection position; Among them, the surface perpendicular to the thickness direction of the wound battery cell is defined as the projection surface, the first connection position forms a first projection on the projection surface, the second connection position forms a second projection on the projection surface, and the filling layer forms a third projection on the projection surface, and the first projection and the second projection are both located outside the third projection.

8. The wound battery cell according to claim 1, wherein: The wound battery cell also includes a wound diaphragm, which includes a first clamping section and a first diaphragm straight section arranged in sequence along the winding direction. The first diaphragm straight section is used to separate the first positive electrode straight section and the first negative electrode straight section, and the first clamping section is used to be clamped by a clamping plate.

9. The wound battery cell according to claim 1, characterized in that: The negative electrode sheet further includes a second clamping segment. The second clamping segment and the first negative electrode straight segment are sequentially arranged along the winding direction. The second clamping segment is used to be clamped by a clamping plate. The second clamping segment is formed by a negative electrode current collector.

10. A battery, characterized in that: include: shell; The wound battery cell according to any one of claims 1 to 9 is arranged inside the casing.

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