Anode strip, battery cell and battery

Abstract

The utility model discloses an anode strip, a battery cell and a battery, and relates to the technical field of lithium batteries, an anode strip body is provided with a plurality of non-corner punching areas arranged at intervals and a plurality of non-corner punching areas arranged at intervals, each corner punching area is provided with a plurality of first holes, and in each corner punching area, a plurality of second holes are formed in each first hole; the hole depth of the first hole is gradually reduced from the center line of the corner punching area along the two opposite sides of the center line. When the battery cell runs, in the corner punching area, the current density is gradually reduced along the two opposite sides of the center line of the corner punching area, and the hole depth of the first hole is gradually reduced from the center line of the corner punching area along the two opposite sides of the center line. According to the invention, the hole depth of the first hole is relatively large at the position with high current density, and the hole depth of the first hole is relatively small at the position with low current density, so that the influence on the quality of the anode strip is reduced while the dynamic window is improved, and the adverse influence on the balance of a battery cell can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium battery, in particular to an anode sheet, a battery cell and a battery. BACKGROUND

[0002] Lithium ion battery has been widely used in the field of consumer digital products, electric vehicles, energy storage and other fields in recent years due to its high energy density, no memory effect, less environmental pollution and other advantages. In the related art, laser drilling is generally performed on the anode sheet of the lithium battery cell to increase the surface tortuosity of the anode sheet, so as to improve the ion diffusion and improve the overall battery dynamics window.

[0003] However, the anode sheet in the related art has low quality due to unreasonable design of the holes, which further causes serious adverse effects on the cell balance (CB) of the battery cell. CONTENT OF THE UTILITY MODEL

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application provides an anode sheet, a battery cell and a battery, which can reduce the adverse effects on the cell balance.

[0005] According to the first aspect of the present application, the anode sheet is applied to the battery cell, and the anode sheet comprises a body, the body is provided with a plurality of corner drilling areas arranged at intervals, the body is further provided with a plurality of non-corner drilling areas arranged at intervals, and the corner drilling areas and the non-corner drilling areas are alternately distributed.

[0006] The corner drilling area is provided with a plurality of first holes, and in each corner drilling area, the hole depth of the first holes gradually decreases from the center line of the corner drilling area to the opposite sides of the center line.

[0007] According to the anode sheet provided by the embodiment of the present application, the body is provided with a plurality of non-corner punching areas arranged at intervals and a plurality of non-corner punching areas arranged at intervals, the corner punching area is provided with a plurality of first holes, and in each corner punching area, the hole depth of the first hole gradually decreases from the center line of the corner punching area to the opposite sides of the center line. When the battery cell is in operation, the current density gradually decreases along the opposite sides of the center line of the corner punching area, and the hole depth of the first hole gradually decreases from the center line of the corner punching area to the opposite sides of the center line. Since the position with a higher current density needs more kinetic promotion, and the higher the hole depth of the first hole, the greater the kinetic promotion, the present application realizes that the hole depth of the first hole is greater at the position with a high current density, and the hole depth of the first hole is smaller at the position with a low current density, the distribution of the hole depth of the first hole is the same as the distribution of the current density, and therefore, the present application can improve the kinetic window while reducing the impact on the quality of the anode sheet, thereby reducing the adverse effects on the balance of the battery cell.

[0008] According to some embodiments of the present application, the width of the corner punching area is wherein t is the thickness of the battery cell.

[0009] According to some embodiments of the present application, the length of the corner punching area is equal to the width of the battery cell.

[0010] According to some embodiments of the present application, the distance between the center lines of every two corner punching areas is wherein t is the thickness of the battery cell, and w is the width of the battery cell.

[0011] According to some embodiments of the present application, each non-corner punching area is provided with a plurality of second holes, and the hole depth of the second hole is proportional to the average current density of the non-corner punching area.

[0012] According to some embodiments of the present application, the plurality of non-corner punching areas includes a first non-corner punching area and a plurality of second non-corner punching areas, the average current density of the first non-corner punching area is greater than the average current density of any second non-corner punching area, and the first hole depth of the second hole of the first non-corner punching area is 20-40 μm.

[0013] According to some embodiments of the present application, the hole depth of the second hole of the second non-corner punching area is a second hole depth, and the second hole depth = the first hole depth * (the average current density of the second non-corner punching area / the average current density of the first non-corner punching area).

[0014] According to some embodiments of the present application, the first non-corner punching region and the second non-corner punching region are both rectangular in shape.

[0015] The second aspect embodiment of the present application provides an electric core, comprising:

[0016] The anode sheet according to any one of the first aspect embodiments of the present application.

[0017] The third aspect embodiment of the present application provides a battery, comprising the electric core according to the second aspect embodiment of the present application.

[0018] Additional aspects and advantages of the present application will be made apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0019] The present application will be further described below in conjunction with the accompanying drawings and embodiments, wherein:

[0020] Figure 1 is a schematic structural diagram of an anode sheet according to an embodiment of the present application. DETAILED DESCRIPTION

[0021] The embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application.

[0022] In the description of the present application, it should be understood that the orientation description, such as the orientation or position relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0023] In the description of the present application, if the meaning of several is more than one, the meaning of multiple is more than two, greater than, less than, more than, etc. is understood as not including the number, above, below, etc. is understood as including the number. If it is described as first, second, it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features.

[0024] In the description of the present application, unless otherwise explicitly limited, the words such as setting, installing, connecting, etc. should be broadly understood, and the person skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0025] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in one or more embodiments or examples.

[0026] The negative electrode capacity of a lithium ion battery is greater than the positive electrode capacity, and the ratio of the negative electrode capacity to the positive electrode capacity is the battery balance CB.

[0027] In the related art, in order to improve the kinetic window of the battery, the anode sheet of the lithium battery cell is laser punched, but the hole distribution in the related art is unreasonable, which leads to low quality of the anode sheet, and causes serious adverse effects on the cell balance (CB) of the cell. Specifically, in the anode sheet, the place with high current density needs more kinetic improvement, and the deeper the punching depth, the more obvious the kinetic improvement, but increasing the punching depth will adversely affect the CB.

[0028] Therefore, the present application provides an anode sheet, a cell and a battery, which can reduce the adverse effects on the cell balance.

[0029] Reference Figure 1 , Figure 1 is a schematic structural diagram of the anode sheet of the embodiment of the present application. The anode sheet of the first aspect embodiment of the present application is applied to a cell, and the anode sheet comprises a body, the body is provided with a plurality of corner punching area arranged at intervals, the body is also provided with a plurality of non-corner punching area arranged at intervals, and the corner punching area and the non-corner punching area are alternately distributed.

[0030] The corner punching area is provided with a plurality of first holes, and in each corner punching area, the hole depth of the first hole gradually decreases from the center line of the corner punching area along the opposite sides of the center line.

[0031] According to the anode sheet provided by the embodiment of the present application, the body is provided with a plurality of non-corner punching areas arranged at intervals and a plurality of non-corner punching areas arranged at intervals, the corner punching area is provided with a plurality of first holes, and in each corner punching area, the hole depth of the first hole gradually decreases from the center line of the corner punching area to the opposite sides of the center line. When the battery cell is in operation, the current density gradually decreases along the opposite sides of the center line of the corner punching area, and the hole depth of the first hole gradually decreases from the center line of the corner punching area to the opposite sides of the center line. Since the position with a higher current density needs more kinetic promotion, and the higher the hole depth of the first hole, the greater the kinetic promotion, the present application realizes that the hole depth of the first hole is greater at the position with a high current density, and the hole depth of the first hole is smaller at the position with a low current density, the distribution of the hole depth of the first hole is the same as the distribution of the current density, and therefore, the present application can improve the kinetic window while reducing the impact on the quality of the anode sheet, thereby reducing the adverse effects on the balance of the battery cell.

[0032] According to some embodiments of the present application, the width of the corner punching area is wherein t is the thickness of the battery cell.

[0033] According to some embodiments of the present application, the length of the corner punching area is equal to the width of the battery cell.

[0034] According to some embodiments of the present application, the distance between the center lines of every two corner punching areas is wherein t is the thickness of the battery cell, and w is the width of the battery cell.

[0035] According to some embodiments of the present application, each non-corner punching area is provided with a plurality of second holes, and the hole depth of the second hole is proportional to the average current density of the non-corner punching area.

[0036] According to some embodiments of the present application, the plurality of non-corner punching areas includes a first non-corner punching area and a plurality of second non-corner punching areas, the average current density of the first non-corner punching area is greater than the average current density of any second non-corner punching area, and the first hole depth of the second hole of the first non-corner punching area is 20 to 40 μm. For example, the first hole depth can be 20 μm, or 30 μm, or 40 μm.

[0037] According to some embodiments of the present application, the hole depth of the second hole of the second non-corner punching area is a second hole depth, and the second hole depth = first hole depth * (average current density of the second non-corner punching area / average current density of the first non-corner punching area).

[0038] According to some embodiments of the present application, the first non-corner punching region and the second non-corner punching region are both rectangular in shape.

[0039] The second aspect of the present application provides an electric core, comprising:

[0040] The anode sheet of any one of the first aspect of the present application.

[0041] The third aspect of the present application provides a battery, comprising the electric core of the second aspect of the present application.

[0042] Specifically, the anode sheet of the present application can be prepared by the following steps:

[0043] Outputting current to the anode sheet and detecting the current density distribution of the anode sheet;

[0044] According to the current density distribution, the surface of the body of the anode sheet is divided into at least two non-corner punching regions; wherein the average current density of each non-corner punching region is different;

[0045] According to the average current density of each non-corner punching region, the hole depth of each non-corner punching region is set; wherein the smaller the average current density of the non-corner punching region, the smaller the corresponding hole depth;

[0046] According to the hole depth of the non-corner punching region, laser punching is performed on the corresponding non-corner punching region.

[0047] First, output current to the anode sheet and detect the current density distribution of the anode sheet, then according to the current density distribution of the anode sheet, the surface of the anode sheet is divided into at least two non-corner punching regions; wherein the average current density of each non-corner punching region is different, then according to the average current density of each non-corner punching region, the hole depth of each non-corner punching region is set; wherein the smaller the average current density of the non-corner punching region, the smaller the corresponding hole depth, then according to the hole depth of the non-corner punching region, laser punching is performed on the corresponding non-corner punching region. Since the average current density of the non-corner punching region is smaller, the corresponding hole depth is smaller in the present application, therefore, the influence on the quality of the anode sheet can be reduced under the premise of ensuring the increase of the surface tortuosity of the anode sheet, thereby improving the ion diffusion and improving the overall battery dynamics window, thereby reducing the adverse effects on the balance of the electric core.

[0048] In some embodiments, the anode sheet is subjected to simulation test, in which the current is output to the anode sheet in sequence, the current output to the anode sheet is gradually increased, and the current density distribution of the anode sheet is recorded each time the simulation is performed until the trend of the current density distribution of the anode sheet is substantially unchanged, and the current density distribution of the last simulation is obtained. Then the surface of the anode sheet is divided into at least two non-corner punched regions according to the current density distribution of the last simulation; and the average current density of each non-corner punched region is different.

[0049] In some embodiments, the surface of the anode sheet is divided into a plurality of non-corner punched regions according to the current density distribution, and the average current density of each non-corner punched region is different, and the number of non-corner punched regions is at least two or more. The size of each non-corner punched region is not limited in the present application, and the size of each non-corner punched region can be the same or different, which can be set according to actual needs by those skilled in the art.

[0050] It can be understood that setting the hole depth of each non-corner punched region according to the average current density of each non-corner punched region can include the following steps:

[0051] Selecting a non-corner punched region with the maximum average current density among the at least two non-corner punched regions as a reference non-corner punched region;

[0052] Obtaining a first hole depth, and taking the first hole depth as the hole depth of the reference non-corner punched region;

[0053] Taking the non-corner punched regions other than the reference non-corner punched region among the at least two non-corner punched regions as non-reference non-corner punched regions;

[0054] Calculating the ratio of the average current density of each non-reference non-corner punched region to the average current density of the reference non-corner punched region;

[0055] Multiplying the ratio by the first hole depth to obtain a second hole depth, and taking the second hole depth as the hole depth of the non-reference non-corner punched region corresponding to the ratio.

[0056] Specifically, according to the current density distribution, the surface of the anode sheet is divided into at least two non-corner punching areas, then the average current density of each non-corner punching area is determined, the non-corner punching area with the maximum average current density is selected from all non-corner punching areas as the reference non-corner punching area, and the other non-corner punching areas are non-reference non-corner punching areas, and the first hole depth set in advance is used as the hole depth of the reference non-corner punching area. Then the ratio of the average current density of the non-reference non-corner punching area to the average current density of the reference non-corner punching area is calculated, and the ratio is multiplied by the first hole depth to obtain the second hole depth, which is the hole depth of the non-reference non-corner punching area corresponding to the ratio. In this way, the hole depth of each non-corner punching area is proportional to the corresponding average current density.

[0057] For example, the surface of the anode sheet is divided into three non-corner punching areas, namely non-corner punching area 1, non-corner punching area 2 and non-corner punching area 3, the average current density of non-corner punching area 1 is A1, the average current density of non-corner punching area 2 is A2, and the average current density of non-corner punching area 3 is A3, A1>A2>A3, then non-corner punching area 1 is the reference non-corner punching area, and non-corner punching area 2 and non-corner punching area 3 are non-reference non-corner punching areas. The first hole depth is H, then the hole depth of non-corner punching area 1 is H, the hole depth of non-corner punching area 2 is H*A2 / A1, and the hole depth of non-corner punching area 3 is H*A3 / A1.

[0058] It can be understood that, according to the hole depth of the non-corner punching area, laser punching is performed on the corresponding non-corner punching area, including but not limited to the following steps:

[0059] According to the hole depth of the non-corner punching area, the power of the laser equipment is adjusted, and laser punching is performed on the corresponding non-corner punching area by the laser equipment.

[0060] Specifically, according to the hole depth of the non-corner punching area, laser punching is performed on the corresponding non-corner punching area. Since the hole depths of each non-corner punching area are different, punching is performed on each non-corner punching area respectively. Before punching, the laser power of the laser equipment is set according to the hole depth of the current non-corner punching area, so that the laser power matches the hole depth, and then laser punching is performed on the current non-corner punching area by the laser equipment. In this way, by adjusting the laser power of the laser equipment, laser punching is performed on the corresponding non-corner punching area according to the hole depth of the non-corner punching area.

[0061] It can be understood that, according to the current density distribution, the surface of the anode sheet is divided into at least two non-corner punching areas, which can include the following steps:

[0062] According to the current density distribution, the surface of the anode sheet is divided into a first non-corner punched region and a second non-corner punched region; wherein the average current density of the first non-corner punched region is greater than the average current density of the second non-corner punched region;

[0063] Correspondingly, setting the hole depth of each non-corner punched region according to the average current density of each non-corner punched region can include the following steps:

[0064] Obtaining a first hole depth, taking the first hole depth as the hole depth of the first non-corner punched region;

[0065] Calculating the ratio of the average current density of the second non-corner punched region to the average current density of the first non-corner punched region;

[0066] Multiplying the ratio by the first hole depth to obtain a second hole depth, and taking the second hole depth as the hole depth of the second non-corner punched region.

[0067] Exemplarily, the total length of the anode sheet is 1800mm, and the anode sheet is folded to form a battery cell after 24 folds, each fold being 75mm. The anode sheet is subjected to simulation test to obtain the current density distribution of the anode sheet, and then the anode sheet is divided into a first non-corner punched region and a second non-corner punched region according to the current density distribution, and one end of the anode sheet is taken as a length scale reference point, then the region located at 525mm to 1275mm is taken as the first non-corner punched region, and the region located at 375mm to 525mm and the region located at 1275mm to 1425mm are taken as the second non-corner punched region. The average current density of the first non-corner punched region is greater than the average current density of the second non-corner punched region. And the ratio of the average current density of the second non-corner punched region to the average current density of the first non-corner punched region is 0.7. The hole depth of the first non-corner punched region is a first hole depth, and the first hole depth is H, then the hole depth of the second non-corner punched region is 0.7H. In an embodiment, H is 20 to 40um, for example, it can be 20um, 30um or 40um. In an embodiment, the regions outside the first non-corner punched region and the second non-corner punched region are also punched, i.e. the regions at 0 to 375mm and 1425mm to 1800mm are punched. Specifically, the hole depth of the regions at 0 to 375mm and 1425mm to 1800mm is 0.6H, and from the boundary of the second non-corner punched region in the direction away from the second punched region, the hole depth decreases by 0.1H every 150mm, until the hole depth is lower than 10um.

[0068] In another embodiment, the punching manner of the anode sheet in the prior art is to punch the whole anode sheet without distinction, the hole depth of the holes on the whole anode sheet is H1, and the length of the anode sheet is L1. In order to reduce the influence on the quality of the anode sheet, the present application provides another punching manner, that is, to punch only between the two tabs of the anode sheet and the 2 folds adjacent to the tabs, the length of the non-corner punching area is L2, and the punching depth is L1*H1 / L2.

[0069] It can be understood that the method for preparing the anode sheet of the embodiment of the present application further comprises the following steps:

[0070] determining the middle line of the corner punching area of the anode sheet;

[0071] laser punching the corner punching area, and the hole depth gradually decreases from the middle line along the opposite sides of the middle line in the corner punching area.

[0072] determining the middle line of the corner punching area of the anode sheet; wherein the width of the corner punching area is wherein t is the thickness of the battery cell, and w is the width of the battery cell; the length of the corner punching area is w; and the distance between the middle lines of every two corner punching areas is In some embodiments, 5mm of tolerance is reserved on both sides of the corner punching area, and thus the width of the corner punching area is

[0073] In an embodiment, referring to Table 1, Table 1 shows the energy density (ED) of the battery cell using the conventional punched anode sheet, the battery cell using the non-punched anode sheet, and the battery cell using the anode sheet of the present application, and the influence of the capacity retention rate (Fading) of the battery cell cycle. It is worth noting that in the conventional punched anode sheet, the hole depth of the whole anode sheet is H. The three battery cells are respectively subjected to cycle test, and the cycle number is 600 times. The process of one cycle is as follows: under the condition of normal temperature, the battery cell is charged to 4.3V at 2C rate, charged to 4.5V at 1.5C rate, charged at 0.02C rate under constant voltage, and discharged to 3V at 0.5C rate under constant voltage.

[0074] As can be seen from Table 1, the ED value of the battery cell using the anode sheet of the present application is higher than that of the battery cell using the conventional punched anode sheet, and is lower than that of the battery cell using the non-punched anode sheet; the capacity retention rate of the battery cell using the anode sheet of the present application is the highest. Therefore, the anode sheet of the present application can reduce the influence on the quality of the anode sheet under the premise of ensuring the increase of the surface tortuosity of the anode sheet, thereby improving the ion diffusion and improving the kinetic window of the overall battery, so as to reduce the adverse influence on the balance of the battery cell.

[0075] Table 1

[0076]

[0077] The embodiments of the present application are described in detail above with reference to the accompanying drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application. Furthermore, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

Claims

1. An anode sheet, characterized by, The anode sheet applied to the battery cell comprises a body provided with a plurality of corner punched areas arranged at intervals, and a plurality of non-corner punched areas arranged at intervals, the corner punched areas and the non-corner punched areas being alternately distributed. The corner punched area is provided with a plurality of first holes, and in each corner punched area, the hole depth of the first holes gradually decreases from the center line of the corner punched area to the opposite sides of the center line.

2. The anode sheet according to claim 1, characterized by The width of the corner punch region is where t is the thickness of the cell.

3. The anode sheet according to claim 2, characterized by The length of the corner punched area is equal to the width of the battery cell.

4. The anode sheet according to claim 3, characterized by The distance between the midlines of each two of the corner punch regions is where t is the thickness of the cell and w is the width of the cell.

5. The anode sheet according to claim 1, characterized by Each non-corner punched area is provided with a plurality of second holes, and the hole depth of the second holes is proportional to the average current density of the non-corner punched area.

6. The anode sheet according to claim 5, characterized by The plurality of non-corner punched areas include a first non-corner punched area and a plurality of second non-corner punched areas, the average current density of the first non-corner punched area is greater than that of any second non-corner punched area, and the first hole depth of the second holes of the first non-corner punched area is 20-40 μm.

7. The anode sheet according to claim 6, characterized by The hole depth of the second holes of the second non-corner punched area is a second hole depth, and the second hole depth = the first hole depth * (the average current density of the second non-corner punched area / the average current density of the first non-corner punched area).

8. The anode sheet according to claim 7, characterized by The shapes of the first non-corner punched area and the second non-corner punched area are both rectangular.

9. An electric cell characterized by The application comprises: The anode sheet according to any one of claims 1-8.

10. A battery, characterized by The battery cell according to claim 9. The application comprises

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