Positive electrode plate and battery cell
By setting grooves in the bending area of the positive electrode, the lithium-ion source is reduced, the lithium plating problem in lithium batteries is solved, safety and lifespan are improved, costs are reduced, and battery energy density is maintained.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHENGHONG KINETIC ENERGY TECH (TAIZHOU) CO LTD
- Filing Date
- 2025-07-07
- Publication Date
- 2026-07-31
AI Technical Summary
During the charging and discharging process of existing lithium batteries, the distance between the positive and negative electrode plates in the bending area increases, resulting in a longer ion migration distance, severe lithium plating, dendrite formation that pierces the separator and causes a short circuit, posing a safety hazard and increasing costs.
Multiple spaced grooves are set in the bending area of the positive electrode to reduce coating material and lower the lithium ion source. The grooves are formed by laser etching to control the groove size and heat accumulation, and to avoid lithium plating and coating material peeling off.
It effectively reduces or avoids lithium plating, improves battery safety and lifespan, reduces costs, avoids damage to coating materials, and maintains battery energy density.
Smart Images
Figure CN224582256U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of battery technology, specifically to a positive electrode sheet and a battery cell. Background Technology
[0002] A square battery consists of a cell, casing, cover, electrolyte, and other components. During battery manufacturing, a separator is placed between the positive and negative electrodes to isolate them. After the positive and negative electrodes and separator are wound together, they are hot-pressed from a cylinder into a flat shape to form the cell. Due to the hot pressing, the cell structure forms bending and non-bending regions. In the bending region, the distance between the positive and negative electrodes increases. During charging and discharging, the ion migration distance is longer than in the non-bending region, leading to lithium plating. As the lithium battery cycles more frequently, lithium plating becomes increasingly severe, forming dendrites that puncture the separator, causing a short circuit, rendering the battery unusable, and even leading to fire or explosion.
[0003] To address the aforementioned issues, existing solutions include applying adhesive tape to the positive electrode sheet in the inner bending area or using a coated separator. However, applying adhesive tape to the inner bending area cannot be done on every single bend of the winding, and can only reduce the risk of lithium plating to a certain extent. Using a coated separator is more expensive than using a regular separator, which increases the cost of lithium batteries. In addition, the presence of the adhesive layer on the separator occupies internal space in the battery, reducing the battery's energy density. Utility Model Content
[0004] In order to overcome the defects in the prior art, this utility model provides a positive electrode sheet and a battery cell that can reduce or avoid lithium plating and improve battery safety.
[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows:
[0006] The first aspect of this utility model discloses a positive electrode sheet, including a current collector and a coating disposed on the current collector. The positive electrode sheet has a positive electrode tab and a bending area. The bending area has a plurality of spaced grooves. The grooves have a first extending direction and a second extending direction. The width of the groove extending along the first extending direction is 0.5 to 2 times the spacing between two adjacent grooves, and the depth of the groove extending along the second extending direction is 0.3 to 0.7 times the thickness of the coating on the positive electrode sheet.
[0007] The positive electrode in this application, by setting a groove in the bending area, can reduce the coating material in the bending area of the positive electrode, thereby reducing the lithium-ion source in the bending area of the positive electrode, thus reducing or avoiding lithium plating during the charging and discharging process, improving the safety and service life of the battery. At the same time, when the size of the groove is set according to the proportion in this application, the laser power or laser duration for forming the groove in the bending area is relatively low, resulting in less heat accumulation, which can avoid damaging the structure of the positive electrode and prevent the binder in the coating material in the bending area from failing, thereby preventing the coating material from falling off the current collector.
[0008] Furthermore, the groove also has a third extending direction, and the planar projection of the groove in the third extending direction is V-shaped, circular, rectangular, regular, irregular, or irregular.
[0009] Furthermore, at least one groove is provided in the third extending direction, and when two or more grooves are provided, the two or more grooves are spaced apart.
[0010] Furthermore, the angle between the third extension direction and the first extension direction is 0° to 180°.
[0011] Furthermore, in the first extending direction, the width of the groove is 1 to 10 mm, and the spacing between two adjacent grooves is 1 to 10 mm. Setting the groove width within this range ensures the adhesion of the coating material in the bending area during lithium plating reduction.
[0012] Furthermore, in the second extending direction, the depth of the groove is 0.01–0.2 mm. If the groove depth is too shallow, less coating material is reduced, resulting in a poor effect in reducing lithium plating; if the groove depth is too deep, it can easily damage the current collector.
[0013] Furthermore, the positive electrode sheet has multiple sets of bending areas and multiple positive electrode tabs. Each set of bending areas includes a first bending area and a second bending area respectively located on both sides of a positive electrode tab. Along the width direction of the positive electrode sheet, the central axis of the first bending area is at a first distance from the current positive electrode tab, and the central axis of the second bending area is at a second distance from the current positive electrode tab. Determining the position of the bending area based on the position of the positive electrode tab allows the groove to be accurately positioned at the bending location of the positive electrode sheet.
[0014] Furthermore, the sum of the first distance and the second distance is the width of the formed battery cell.
[0015] Furthermore, the width of the bending region increases with the increase of the distance from the first end of the positive electrode sheet. During the winding of the positive electrode sheet, as the number of winding turns increases, the diameter from the inward roll to the outward roll gradually increases, and after hot pressing, the area of the bending region from the inward roll to the outward roll gradually increases.
[0016] The second aspect of this utility model discloses a battery cell, including the positive electrode sheet described in any one of the first aspects.
[0017] Due to the application of the above technical solution, this utility model has the following advantages compared with the prior art:
[0018] This application reduces the amount of coating material in the bending area of the positive electrode by setting multiple spaced grooves, thereby reducing the lithium-ion source in the bending area and thus reducing or avoiding lithium plating, improving battery safety and lifespan. At the same time, when the size of the grooves is set according to the proportions in this application, the laser power or laser duration for forming the grooves in the bending area is relatively low, resulting in less heat accumulation. This avoids damage to the structure of the positive electrode and prevents the binder in the coating material in the bending area from failing, thereby preventing the coating material from falling off the current collector.
[0019] To make the above and other objects, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description
[0020] 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.
[0021] Figure 1 This is a partial unfolded top view of a positive electrode sheet provided in an embodiment of this utility model;
[0022] Figure 2 This is a partial cross-sectional view of a positive electrode sheet provided in an embodiment of this utility model;
[0023] Figure 3 This is a partial top view of a positive electrode sheet provided in an embodiment of this utility model;
[0024] Figure 4 This is a schematic diagram of a battery cell winding provided in an embodiment of the present invention;
[0025] Figure 5 This is a front view of a battery cell provided in an embodiment of this utility model.
[0026] The reference numerals in the above figures are as follows: 1. Positive electrode sheet; 2. Coating; 3. Current collector; 4. First bending area; 5. Second bending area; 6. Groove; 7. Positive electrode tab; 8. Negative electrode tab. Detailed Implementation
[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. In addition, the accompanying drawings of the present invention are only simple schematic illustrations and are not depictions based on actual dimensions, as stated in advance.
[0028] In this utility model, it should be noted that the terms "upper," "lower," "inner," "outer," "forward," "backward," "between," "nearer," and "farthest" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing this utility model and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. It should also be noted that, unless otherwise explicitly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0029] It should be understood that while terms such as "first," "second," and "third" may be used in this document to describe various components or signals, these components or signals should not be limited by these terms. These terms are primarily used to distinguish one component from another, or one signal from another. Furthermore, the term "or" as used herein should, as appropriate, include any combination of one or more of the related listed items.
[0030] Reference Figures 1-5 This application provides a positive electrode 1, which includes a current collector 3 and a coating 2 applied to the current collector 3. The positive electrode 1 has a positive tab 7 and a bending region, which is the bending position of the positive electrode 1 when it is wound with a negative electrode and a separator to form a battery cell. The bending region has a plurality of spaced grooves 6, each groove having a first extending direction a and a second extending direction. The second extending direction is a direction from the surface of the coating 2 towards the current collector 3 along its thickness direction.
[0031] Optionally, the groove 6 is provided on one or both sides of the positive electrode 1. The groove 6 can be formed on the positive electrode 1 in various ways, such as by using at least one method of metal cutting tool, laser cutting tool or liquid etching tool. In this embodiment, the method of forming the groove on the surface of the positive electrode 1 by laser etching will be described. The groove 6 can be formed on the positive electrode 1 before the step of winding to form the battery cell.
[0032] By using the above structure, the embodiments of this application reduce the coating material in the bending area of the positive electrode 1, thereby reducing the lithium-ion source in the bending area of the positive electrode 1, thereby reducing or avoiding lithium plating and improving the safety and service life of the battery.
[0033] In this embodiment, Figure 1 An exemplary partial structure of the positive electrode 1 in its unfolded state is shown. For example... Figure 1 As shown, the positive electrode 1 has a continuous extending structure. It has multiple sets of bending areas and multiple positive electrode tabs 7. Each set of bending areas includes a first bending area 4 and a second bending area 5 respectively located on both sides of a positive electrode tab 7. The central axis of the first bending area 4 is at a first distance from the positive electrode tab 7, and the central axis of the second bending area 5 is at a second distance from the positive electrode tab 7. The direction of the central axis is the same as the width direction of the positive electrode 1. Along the extending direction of the positive electrode 1, the first bending area 4 and the second bending area 5 are alternately arranged, and their widths gradually increase along the extending direction of the positive electrode 1. The extending direction of the positive electrode 1 is the same as the first extending direction a of the groove 6, and the width direction of the positive electrode 1 is perpendicular to the first extending direction a.
[0034] Understandably, during the winding process of forming the battery cell, as the number of winding turns increases, the diameter of the core gradually increases from the inner to the outer turns, and the spacing between the multiple positive electrode tabs 7 gradually increases with the number of winding turns to ensure that the positive electrode tabs are aligned after winding. After hot pressing, the width of the bending area of the positive electrode sheet 1 increases with the distance from the first end of the positive electrode sheet 1. The width direction of the bending area is the same as the extension direction of the positive electrode sheet 1, and the length direction of the bending area is the same as the width direction of the positive electrode sheet 1. The first end of the positive electrode sheet 1 is located in the innermost layer of the winding.
[0035] The positive electrode 1, negative electrode 1, and separator are wound and hot-pressed to form a battery cell. The sum of the first distance and the second distance is the width of the battery cell. The first and second distances can be calculated using any position of the positive electrode tab 7 as a reference point. In this embodiment, Figure 5 An exemplary diagram illustrating the calculation of the first and second distances is provided. For example... Figure 5 As shown, the calculation reference point for the first and second distances is the edge of the positive electrode 7 closest to the first end of the battery cell. The first distance between the center of the first bending area 4 and the positive electrode 7 is B, and the second distance between the second bending area 5 and the positive electrode 7 is AB, where A is the width of the battery cell, and B is the distance from the edge of the positive electrode 7 closest to the first end of the battery cell to the first end of the battery cell, i.e., the end furthest from the negative electrode 8. The first end of the battery cell is the end of the battery cell that is closer to the positive electrode 14 than the other end; the specific position and relationship are as follows... Figure 4 and Figure 5 As shown.
[0036] It should be noted that the width of cell A is known before the positions of the first bending area 4 and the second bending area 5 are calculated, and will not be described in detail here.
[0037] After calculating the central axis of the first bending area 4 and the second bending area 5, the widths of the first bending area 4 and the second bending area 5 can be set according to the actual situation. Optionally, the width W of the first bending area 4 and the second bending area 5 is greater than or equal to the width of the cell bending section, thereby increasing the number of grooves at the bending position to ensure a relatively greater reduction in coating material in the cell bending section, thus ensuring a better effect in reducing or avoiding lithium plating.
[0038] like Figure 2 and Figure 3 As shown, in the first extending direction a, the width W1 of the groove 6 is 0.5 to 2 times the spacing W2 between two adjacent grooves 6, and the sum of multiple W1 and multiple W2 is equal to the width of a bending area W.
[0039] In the second extending direction, the depth H of the groove 6 is 0.3 to 0.7 times the thickness of the coating 2 on the positive electrode 1.
[0040] Optionally, in the first extending direction, the width of the groove 6 is 1 to 10 mm, and the spacing between two adjacent grooves 6 is 1 to 10 mm. In the second extending direction, the depth of the groove 6 is 0.01 to 0.2 mm.
[0041] Optionally, the groove 6 can be set to be strip-shaped, block-shaped, regular-shaped, irregular-shaped, or irregular-shaped.
[0042] The groove 6 also has a third extending direction b, and the planar projection of the groove 6 in the third extending direction b is V-shaped, circular, rectangular, regular, irregular or irregular.
[0043] In some embodiments, the angle between the third extending direction b and the first extending direction a is 0° to 180°.
[0044] In some embodiments, a continuous groove or two or more spaced groove segments are provided in the third extending direction b.
[0045] In some embodiments, the projections of the groove 6 are offset or at least partially overlap in the first extending direction a and the third extending direction b.
[0046] It should be noted that, in the first extending direction a, the width and spacing of the multiple grooves 6 can be the same or different; in the second extending direction, the depth of the multiple grooves 6 can be the same or different; and in the third extending direction b, the length of the multiple grooves 6 can be the same or different. The specific settings can be made according to the actual situation.
[0047] This application also provides a battery cell, which includes the positive electrode plate described above. Since the battery cell of this application has the positive electrode plate described above, the beneficial effects brought about by the positive electrode plate are explained above and will not be repeated here.
[0048] This utility model uses specific embodiments to illustrate the principle and implementation of the utility model. The above description of the embodiments is only for the purpose of helping to understand the method and core idea of the utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of the utility model. Therefore, the content of this specification should not be construed as a limitation of the utility model.
Claims
1. A positive electrode sheet comprising a current collector and a coating layer provided on the current collector, the positive electrode sheet having a positive electrode tab provided thereon, characterized in that, The positive electrode sheet has a bending area, and the bending area has a plurality of spaced grooves. The grooves have a first extending direction and a second extending direction. The width of the groove extending along the first extending direction is 0.5 to 2 times the spacing between two adjacent grooves, and the depth of the groove extending along the second extending direction is 0.3 to 0.7 times the coating thickness on the positive electrode sheet.
2. The positive electrode sheet according to claim 1, characterized by The groove also has a third extending direction, and the planar projection of the groove in the third extending direction is V-shaped, circular, rectangular, regular, irregular, or irregular.
3. The positive electrode sheet according to claim 2, characterized by At least one groove is provided in the third extending direction, and when there are two or more grooves, the two or more grooves are spaced apart.
4. The positive electrode sheet according to claim 2, characterized by The angle between the third extension direction and the first extension direction is 0° to 180°.
5. The positive electrode sheet according to claim 1, characterized by In the first extending direction, the width of the groove is 1 to 10 mm, and the distance between two adjacent grooves is 1 to 10 mm.
6. The positive electrode sheet according to claim 1, characterized by In the second extending direction, the depth of the groove is 0.01 to 0.2 mm.
7. The positive electrode sheet according to claim 1, characterized by The positive electrode sheet has multiple sets of bending areas and multiple positive electrode tabs. Each set of bending areas includes a first bending area and a second bending area respectively located on both sides of a positive electrode tab. Along the width direction of the positive electrode sheet, the central axis of the first bending area has a first distance from the current positive electrode tab, and the central axis of the second bending area has a second distance from the current positive electrode tab.
8. The positive electrode sheet according to claim 7, characterized by The sum of the first distance and the second distance is the width of the formed cell.
9. The positive electrode sheet according to claim 7, characterized by The width of the bending region increases with the increase of the distance from the first end of the positive electrode.
10. An electric cell characterized by Includes the positive electrode sheet as described in any one of claims 1 to 9.