Battery pole piece, battery cell main body and battery cell structure

Abstract

This utility model relates to the technical field of battery electrode sheets, and discloses a battery electrode sheet, a battery cell body, and a battery cell structure. When the electrode sheet is in an unfolded state, multiple pairs of arc-shaped cuts are arranged at intervals along the length of the electrode sheet at both ends along the width direction. When the electrode sheet is wound into a wound structure, the multiple pairs of arc-shaped cuts form arc-shaped notch structures at the four corners of the electrode sheet, and the depth of the electrode sheet removed by each pair of arc-shaped cuts in the width direction increases with the increase of the number of winding layers of the electrode sheet. The four notch structures of the electrode sheet in the wound state actually correspond one-to-one with the four corners of the aluminum-plastic film. This can increase the distance between the four corners of the aluminum-plastic film and the battery cell body, thereby avoiding the interaction between the four corners of the battery cell body and the four corners of the aluminum-plastic film when the battery cell body expands outward. This solves the problem that the aluminum-plastic film is prone to breakage during the cycling process of the battery cell body, and improves the safety of the battery cell structure.

Description

Technical Field

[0001] This utility model relates to the technical field of battery cell structure, and in particular to a battery electrode, a battery cell body, and a battery cell structure. Background Technology

[0002] As market demand for long-lasting lithium-ion batteries increases, manufacturers are pushing the limits of cell design, even making the aluminum-plastic film used to encase the cells thinner and lighter. For more details, please refer to... Figure 1 The length, width, and height of the battery cell body 2 are designed towards the extreme, and the thickness of the aluminum-plastic film 1 used to wrap the battery cell body 2 is becoming thinner and thinner. After the aluminum-plastic film 1 wraps the battery cell body 2, the strength of the four corners of the aluminum-plastic film 1 is relatively weak. When the internal battery cell body 2 expands after long-term operation and pushes the aluminum-plastic film 1 outward, it is easy to cause the aluminum-plastic film 1 to break at the corners, which will lead to battery leakage and affect the safety of battery use. Utility Model Content

[0003] This utility model provides a battery electrode, a battery cell body, and a battery cell structure, mainly solving the technical problem of how to prevent damage at the four corners of the aluminum-plastic film used to wrap the battery cell body.

[0004] To achieve the above objectives, this utility model provides the following technical solution:

[0005] A battery electrode sheet, when the electrode sheet is in an unfolded state, has multiple pairs of arc-shaped cuts arranged sequentially and spaced apart along the length of the electrode sheet at both ends along the width direction. When the electrode sheet is wound into a wound structure, the multiple pairs of arc-shaped cuts form arc-shaped notch structures at the four corners of the electrode sheet, and the depth of the electrode sheet removed by each pair of arc-shaped cuts in the width direction increases with the increase of the number of winding layers of the electrode sheet.

[0006] In one of the technical solutions, after the electrode sheet is wound into a wound structure, the electrode sheet includes a flat area and two arc-shaped areas on opposite sides of the flat area. Each arc-shaped area has two arc-shaped notch structures. The depth of the electrode sheet cut off in the width direction by each pair of arc-shaped notches increases with the increase of the number of layers of the electrode sheet wound in the arc-shaped area.

[0007] In one of the technical solutions, for each additional layer of the electrode wrapped around the arc area on the same side, the depth of the arc-shaped cut in the width direction of the electrode increases by 0.05mm-0.1mm.

[0008] In one technical solution, the electrode sheet has two ends along its length, designated as a first end and a second end. The first end is used for winding around the innermost loop, and the second end is used for winding around the outermost loop. Pairs of arc-shaped cuts are arranged at intervals from the first end to the second end. Let D be the depth to which a pair of arc-shaped cuts removes material from the electrode sheet along its width. n D n =D n-2 +D0, where D0 is 0.05mm-0.2mm.

[0009] In one technical solution, let the width of the electrode be W, and the maximum D at the second end be... max Satisfy D max *2≤1 / 8*W.

[0010] In one of the technical solutions, let D be the edge line of the electrode in the width direction, let any arc-shaped cut intersect the line D at points A and B, let the arc-shaped cut cut along the width direction of the electrode to point C, and let the angle between the line AC and the line D and the angle between the line BC and the line D not exceed 45°.

[0011] This application also provides a battery cell body, including a positive electrode sheet, a negative electrode sheet, and a separator. The positive electrode sheet, the separator, and the negative electrode sheet are stacked and wound in sequence to form a wound structure. The positive electrode sheet and the negative electrode sheet have the structure of the electrode sheet described above. After the positive electrode sheet and the negative electrode sheet are wound together, the positions of each pair of arc-shaped cuts on the positive electrode sheet correspond to the positions of each pair of arc-shaped cuts on the negative electrode sheet, so that the positions of the four notch structures formed after the positive electrode sheet is wound can correspond one-to-one with the positions of the four notch structures formed after the negative electrode sheet is wound.

[0012] In one of the technical solutions, the width of the negative electrode sheet is greater than the width of the positive electrode sheet, and when the positive electrode sheet and the negative electrode sheet have the same number of winding turns, the arc-shaped cut on the positive electrode sheet is greater than or equal to the arc-shaped cut on the negative electrode sheet.

[0013] This application also provides a battery cell structure, including an aluminum-plastic film, a positive electrode tab, a negative electrode tab, and the battery cell body described above. The positive electrode tab is connected to the positive electrode plate, and the negative electrode tab is connected to the negative electrode plate. The aluminum-plastic film wraps the battery cell body inside, and the positive electrode tab and the negative electrode tab are exposed outward relative to the aluminum-plastic film. Multiple notch structures of the battery cell body correspond one-to-one with multiple corner positions of the aluminum-plastic film.

[0014] In one of the technical solutions, the two ends of the notch structure are set to points P and Q, respectively. The vertex of the aluminum-plastic film at the corner is set to M. The vertical distance from point M to line PQ is set to L, where L is greater than or equal to 1.5 mm.

[0015] Compared with the prior art, the battery electrode provided by this utility model has at least the following beneficial effects:

[0016] This solution involves further cutting away from both ends of the battery electrode (i.e., positive or negative electrode) in the width direction, creating multiple pairs of arc-shaped cuts at both ends. Furthermore, during the fabrication of the wound cell body, after the electrode is wound into a coiled structure, these arc-shaped cuts create arc-shaped notches at the four corners of the electrode. When the aluminum-plastic film wraps around the cell body to form the cell structure, the four notches of the wound electrode correspond one-to-one with the four corners of the aluminum-plastic film. This increases the distance between the four corners of the aluminum-plastic film and the cell body, thus avoiding the interaction between the four corners of the cell body and the four corners of the aluminum-plastic film when the cell body expands outward. This solves the problem of the aluminum-plastic film easily breaking during cycling, improving the safety of the cell structure. Secondly, compared to a square notch structure, the arc-shaped notch structure retains more electrode area, ensuring that the cell body maintains a better energy density even with four notches. In addition, this solution also designs the depth of the arc-shaped cut in the width direction of the electrode sheet to increase with the increase of the number of electrode sheet winding layers, so that when the electrode sheet is wound, a relatively neat notch structure can be formed. This ensures that there is more clearance space between the corner of the wound electrode sheet and the corner of the aluminum-plastic film, thereby improving the reliability of preventing the aluminum-plastic film from breaking at the corner. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the existing battery cell structure;

[0019] Figure 2 This is a schematic diagram of the structure of a battery electrode provided in an embodiment of this application;

[0020] Figure 3 for Figure 2 A magnified view of a section at point E in the middle;

[0021] Figure 4 A bottom view of a battery cell body provided in an embodiment of this application;

[0022] Figure 5 A front view of a battery cell body provided in an embodiment of this application;

[0023] Figure 6 This is a schematic diagram of a battery cell structure provided in an embodiment of this application.

[0024] Figure label:

[0025] 1. Aluminum-plastic film; 2. Battery cell body; 21. Electrode; 211. Arc-shaped cut; 212. Notch structure; 213. First end; 214. Second end; 215. Straight area; 216. Arc area; 3. Positive electrode tab; 4. Negative electrode tab. Detailed Implementation

[0026] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0027] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0028] It should be understood that the terms "upper", "lower", "top", "bottom", "inner", "outer", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0030] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments.

[0031] Please see Figure 2This utility model embodiment provides a battery electrode, wherein the electrode 21 can be a positive electrode or a negative electrode within the battery cell body. This electrode 21 is as follows: Figure 2 When in the unfolded state, the electrode 21 has multiple pairs of arc-shaped cuts 211 at both ends along the width direction Y. These arc-shaped cuts 211 are arranged alternately along the length direction X of the electrode 21. For clarity, the two ends of the electrode 21 along the length direction can be designated as the first end 213 and the second end 214. The first end 213 is used for winding around the innermost loop, and the second end 214 is used for winding around the outermost loop. Each pair of arc-shaped cuts 211 can be understood as being arranged alternately from the first end 213 to the second end 214. The depth to which a certain pair of arc-shaped cuts 211 cuts the electrode 21 along the width direction Y can be defined as D. n (where n is a positive number greater than 1), then Figure 2 The depth of the first pair of arc-shaped incisions 211 is understood as D1, the depth of the second pair of arc-shaped incisions 211 is understood as D2, and so on, until the depth of the Nth pair of arc-shaped incisions 211 is understood as D... n .

[0032] Please refer to the following: Figure 2 , Figure 4 and Figure 5 During the manufacturing process of the wound cell body 2, the electrode 21, as Figure 4 and Figure 5 After being wound into a wound structure, multiple pairs of arc-shaped cuts 211 will form arc-shaped notch structures 212 at the four corners of the electrode 21. In fact, each notch structure 212 is formed by superimposing multiple odd-numbered or even-numbered arc-shaped cuts 211. Furthermore, the spacing between multiple pairs of arc-shaped cuts 211 depends on the winding radius of the cell body 2. When the winding radius is determined, the specific number of arc-shaped cuts 211 in the length direction X depends on the number of winding layers of the cell body 2.

[0033] Specifically, this solution further processes the two ends of the battery electrode 21 in the width direction by cutting off multiple pairs of arc-shaped cuts 211 at both ends of the electrode 21 in the width direction Y. Furthermore, when the electrode 21 is wound into a wound structure during the manufacturing process of the wound cell body 2, the multiple pairs of arc-shaped cuts 211 will form arc-shaped notch structures 212 at the four corners of the electrode 21. When the aluminum-plastic film 1 wraps the cell body 2 to form the cell structure, the four notch structures 212 of the electrode 21 in the wound state actually correspond one-to-one with the four corners of the aluminum-plastic film 1. This can increase the distance between the four corners of the aluminum-plastic film 1 and the cell body 2, thereby avoiding the interaction between the four corners of the cell body 2 and the four corners of the aluminum-plastic film 1 when the cell body 2 expands outward. This solves the problem that the aluminum-plastic film 1 is prone to breakage during the cycle process of the cell body 2, and improves the safety of the cell structure. Secondly, compared to the square notch structure 212, the arc-shaped notch structure 212 can retain more area of ​​the electrode sheet, ensuring that the cell body 2 can still have better energy density even with four notch structures 212. Furthermore, this design also increases the depth of the arc-shaped cut 211 in the width direction Y of the electrode sheet 21 as the number of winding layers of the electrode sheet 21 increases (this sentence can also be understood as D). n =D n-2 +D0, where D0 is greater than 0), so that when the electrode is wound, a notch structure 212 with a relatively neat notch can be formed. This ensures that there is more clearance space between the corner of the wound electrode 21 and the corner of the aluminum-plastic film 1, thereby improving the reliability of preventing the aluminum-plastic film 1 from breaking at the corner.

[0034] Please refer to the following: Figure 4 and Figure 5 After the electrode 21 is wound into a wound structure, the electrode 21 will include a flat area 215 and two arc-shaped areas 216. The two arc-shaped areas 216 are actually located on opposite sides of the flat area 215. Since each arc-shaped area 216 has two corners, each arc-shaped area 216 actually has two arc-shaped notch structures 212. In fact, the depth of the electrode 21 removed by each pair of arc-shaped notches 211 in the width direction Y increases with the increase of the number of layers of the electrode 21 wound in the arc-shaped area 216. Preferably, with each additional layer of the arc-shaped area 216 wound, the depth of the electrode 21 removed by the arc-shaped notches 211 in the width direction Y increases by 0.05mm-0.1mm, that is, D0 = 0.05mm-0.2mm.

[0035] This supplementary explanation is for D. n and D n-1 The size of D n and D n-1 The number of winding turns at the two pairs of arc-shaped cuts 211 can be understood as the same, therefore D nCan be with D n-1 Equal, D n It can also be slightly larger than D. n-1 For example, designed as D. n -D n-1 =0.05mm-0.1mm, but D n It must satisfy greater than D n-2 conditions.

[0036] Please see Figure 2 Let the width of electrode 21 in the width direction Y be W. In this embodiment, the maximum D of the second end 214 is... max Designed to meet D max *2≤1 / 8*W, this design can prevent the electrode 21 from being die-cut too much in the width direction Y, which would lead to insufficient strength of the electrode 21 and cause it to break easily.

[0037] Please refer to the following: Figure 2 and Figure 3 Let D be the edge line of the electrode 21 in the width direction Y. Let any arc-shaped cut 211 intersect the straight line D at points A and B. Let the arc-shaped cut 211 cut along the width direction Y of the electrode 21 to point C. The angle α between the straight line AC and the straight line D, and the angle between the straight line BC and D, do not exceed 45°. This makes the arc ACB a major arc or a semicircle. Thus, when the electrode 21 is wound into a winding structure, the circumferential angle corresponding to the arc-shaped notch structure 212 formed is at most 90°. This prevents the arc-shaped notch structure 212 from having sharp corners, thereby ensuring that there is sufficient clearance between the corner of the battery cell body 2 and the corner of the aluminum-plastic film 1, and further preventing the corner of the aluminum-plastic film 1 from being damaged.

[0038] Please see Figure 4 and Figure 5 This embodiment also provides a battery cell body, which includes a positive electrode sheet, a negative electrode sheet, and a separator. The positive electrode sheet, separator, and negative electrode sheet are sequentially stacked and wound into a wound structure. Both the positive and negative electrode sheets adopt the structure of the electrode sheets described above. After the positive and negative electrode sheets are wound together, the positions of each pair of arc-shaped cuts 211 on the positive electrode sheet correspond to the positions of each pair of arc-shaped cuts 211 on the negative electrode sheet, so that the positions of the four notch structures 212 formed after the positive electrode sheet is wound correspond one-to-one with the positions of the four notch structures 212 formed after the negative electrode sheet is wound. Through this design, when... Figure 6As shown, after the battery cell body 2 is wrapped with aluminum-plastic film 1, there is ample clearance between the corners of the battery cell body 2 and the corresponding corners of the aluminum-plastic film 1, thus preventing damage to the corners of the aluminum-plastic film 1. Furthermore, to ensure that the negative electrode paste on the negative electrode sheet covers the positive electrode paste on the positive electrode sheet, preventing lithium ions from depositing into unusable locations on the positive electrode sheet, the width of the negative electrode sheet is generally 1-2 mm wider than the width of the positive electrode sheet. In practice, when the positive and negative electrode sheets have the same number of winding turns, the arc-shaped cut 211 on the positive electrode sheet needs to be larger than or equal to the arc-shaped cut 211 on the negative electrode sheet to ensure that the negative electrode sheet can cover the positive electrode sheet.

[0039] Please see Figure 6 This embodiment also provides a battery cell structure, which includes an aluminum-plastic film 1, a positive electrode tab 3, a negative electrode tab 4, and the aforementioned battery cell body 2. The positive electrode tab 3 is connected to the positive electrode plate inside the battery cell body 2, and the negative electrode tab 4 is connected to the negative electrode plate inside the battery cell body 2. The aluminum-plastic film 1 encloses the battery cell body 2. The positive electrode tab 3 and the negative electrode tab 4 are exposed outward relative to the aluminum-plastic film 1, allowing the battery cell body 2 to discharge outward or charge inward. Multiple notch structures 212 of the battery cell body 2 correspond one-to-one with multiple corner positions of the aluminum-plastic film 1, ensuring sufficient clearance between the corner positions of the battery cell body 2 and the corner positions of the aluminum-plastic film 1, thereby preventing damage to the corner positions of the aluminum-plastic film 1. Please refer to [further details omitted]. Figure 5 and Figure 6 Let the two ends of the notch structure 212 be point P and point Q respectively, let the vertex of the aluminum-plastic film 1 at the corner be M, and let the vertical distance from point M to the straight line PQ be L. L is preferably greater than or equal to 1.5mm. Specifically, this ensures that there is enough clearance between the corner of the battery cell body 2 and the corner of the aluminum-plastic film 1 to prevent the corner of the aluminum-plastic film 1 from being damaged.

[0040] The above are merely preferred embodiments of the present utility model, and only specifically describe the technical principles of the present utility model. These descriptions are only for explaining the principles of the present utility model and should not be construed as limiting the scope of protection of the present utility model in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model, as well as other specific embodiments of the present utility model that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of the present utility model.

Claims

1. A battery electrode, characterized in that, When the electrode is in the unfolded state, multiple pairs of arc-shaped cuts are arranged at intervals along the length of the electrode at both ends along the width direction. When the electrode is wound into a wound structure, the multiple pairs of arc-shaped cuts form arc-shaped notch structures at the four corners of the electrode. The depth of the electrode cut by each pair of arc-shaped cuts in the width direction increases with the increase of the number of winding layers of the electrode.

2. The battery electrode as described in claim 1, characterized in that, When the electrode is wound into a wound structure, the electrode includes a flat area and two arc areas on opposite sides of the flat area. Each arc area has two arc-shaped notch structures. The depth of the electrode removed in the width direction by each pair of arc-shaped notches increases with the increase of the number of layers of the electrode wound in the arc area.

3. The battery electrode as described in claim 2, characterized in that, For each additional layer the electrode is wound around in the arc region on the same side, the depth of the arc-shaped cut in removing the electrode in the width direction increases by 0.05mm-0.1mm.

4. The battery electrode as described in claim 3, characterized in that, Let the two ends of the electrode in the length direction be the first end and the second end, wherein the first end is used for winding on the innermost loop and the second end is used for winding on the outermost loop. Each pair of arc-shaped cuts is arranged at intervals from the first end to the second end. Let D be the depth to which a pair of arc-shaped cuts removes material from the electrode in the width direction. n D n =D n-2 +D0, where D0 is 0.05mm-0.2mm.

5. The battery electrode as described in claim 4, characterized in that, it is provided that... The width of the electrode is W, and the maximum value D at the second end is... max Satisfy D max *2≤1 / 8*W.

6. The battery electrode as described in claim 1, characterized in that, Let D be the edge line of the electrode in the width direction. Let any arc-shaped cut intersect the line D at points A and B. Let the arc-shaped cut cut along the width direction of the electrode to point C. The angle between the line AC and the line D, and the angle between the line BC and the line D, do not exceed 45°.

7. A battery cell body, characterized in that, The device includes a positive electrode, a negative electrode, and a separator. The positive electrode, the separator, and the negative electrode are stacked and wound in sequence to form a wound structure. Both the positive electrode and the negative electrode adopt the structure of the electrode as described in any one of claims 1 to 6. After the positive electrode and the negative electrode are wound together, the positions of each pair of arc-shaped cuts on the positive electrode correspond to the positions of each pair of arc-shaped cuts on the negative electrode, so that the positions of the four notch structures formed after the positive electrode is wound correspond one-to-one with the positions of the four notch structures formed after the negative electrode is wound.

8. The battery cell body as described in claim 7, characterized in that, The width of the negative electrode is greater than the width of the positive electrode, and when the positive electrode and the negative electrode have the same number of winding turns, the arc-shaped cut on the positive electrode is greater than or equal to the arc-shaped cut on the negative electrode.

9. A battery cell structure, characterized in that, The battery cell includes an aluminum-plastic film, a positive tab, a negative tab, and a battery cell body as described in any one of claims 7 or 8. The positive tab is connected to the positive electrode plate, the negative tab is connected to the negative electrode plate, the aluminum-plastic film encloses the battery cell body, the positive tab and the negative tab are exposed outward relative to the aluminum-plastic film, and the multiple notch structures of the battery cell body correspond one-to-one with the multiple corner positions of the aluminum-plastic film.

10. The cell structure as described in claim 9, characterized in that, wherein... The two ends of the notch structure are located at points P and Q, respectively. Let M be the vertex of the aluminum-plastic film at the corner, and let L be the vertical distance from point M to the straight line PQ, where L is greater than or equal to 1.5 mm.

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