Positive plate, battery cell and battery
By creating notches on the edge of the positive electrode, the problem of lithium deposition during high-rate charging of lithium-ion batteries is solved, thus improving the safety and performance of the battery.
Patent Information
- Application Number
- CN202423122869.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-17
- Publication Date
- 2025-12-19
- Estimated Expiration
- 2034-12-17
AI Technical Summary
In existing technologies, lithium-ion batteries are prone to lithium plating at the battery edge during high-rate charging, which affects battery capacity and safety.
By creating notches at the edge of the positive electrode, the area and amount of active material are reduced, thereby decreasing the amount of lithium ions deposited in the electrochemical reaction. This improves the lithium plating problem by increasing the local CB value at the electrode edge.
It effectively reduces the number of lithium ions deposited at the edge of the positive electrode, improves the lithium deposition problem during high-rate charging, and enhances the safety and performance of the battery.
Smart Images
Figure CN223693140U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to new energy battery technical field especially relates to a positive pole piece, electric core and battery. BACKGROUND
[0002] Lithium ion battery, also known as lithium battery, is a kind of secondary battery relying on lithium ion moving between positive pole and negative pole to achieve charge and discharge purpose. Under the background of the development of electric vehicles, electric light vehicles, electric tools, consumer electronics and new energy storage industries, lithium battery has obtained wide market application by virtue of the advantages such as high energy density, high discharge power, long cycle life, no memory effect and green environmental protection.
[0003] However, with the wide application of lithium ion battery, some technical problems gradually appear. In the charge and discharge process of lithium ion battery, especially in the area close to the tab on the side, the current of charge and discharge process is relatively large. In the case of high-rate charging, such large current is easy to cause lithium precipitation in the edge area of the battery. Lithium precipitation refers to the precipitation of lithium ion on the negative electrode surface in the form of metallic lithium, which not only affects the capacity and performance of the battery, but also may pose a threat to the safety of the battery. SUMMARY
[0004] The utility model aims at at least one of the technical problems existing in the prior art. To this end, the utility model provides a positive pole piece, which can improve the problem of lithium precipitation in the edge position of the pole piece in the high-rate charging process by opening a notch on the edge.
[0005] The utility model further provides an electric core with the above-mentioned positive pole piece.
[0006] The utility model further provides an electric core with the above-mentioned positive pole piece.
[0007] The utility model further provides a battery with the above-mentioned electric core.
[0008] According to the positive pole piece of the first aspect embodiment of the utility model, comprising:
[0009] Current collector;
[0010] Coating layer, the coating layer is formed on at least one side of the current collector along its thickness direction;
[0011] Wherein, set two mutually parallel edges on the positive pole piece as first edge and second edge respectively, the positive pole piece further includes tab, the tab is connected with the current collector, and extends to the outside of the current collector via the first edge, at least one notch is opened on the first edge, the notch penetrates the current collector and the coating layer.
[0012] According to the positive plate provided by the embodiment of the present application, the following beneficial effects are achieved:
[0013] The positive plate provided by the embodiment of the present application is provided with a notch on the edge, so that the area and quantity of the active material of the positive plate are reduced, thereby reducing the quantity of lithium ions precipitated from the positive plate in the electrochemical reaction process, especially the quantity of lithium ions precipitated from the edge of the positive plate, and the local CB (the ratio of the negative capacity to the positive capacity in the lithium ion battery) at the edge position of the plate is increased to improve the problem of lithium precipitation at the edge position of the plate in the high-rate charging process.
[0014] According to some embodiments of the present application, the number of the notch is one, and the relationship among the projection area S of the notch, the length L of the coating layer and the width W of the coating layer in the thickness direction of the positive plate is as follows: 0.1%*L*W≤S≤1%*L*W.
[0015] Alternatively, the number of the notch is multiple, and the relationship among the total area S of the projection areas of the multiple notches, the length L of the coating layer and the width W of the coating layer in the thickness direction of the positive plate is as follows: 0.1%*L*W≤S≤1%*L*W.
[0016] According to some embodiments of the present application, the number of the notch is one, and the notch is any one of a triangle, an arc, a rectangle and a trapezoid.
[0017] Alternatively, the number of the notch is multiple, and the notch is any one or a combination of multiple of the triangle, the arc, the rectangle and the trapezoid.
[0018] According to some embodiments of the present application, at least one notch is provided on the second edge.
[0019] According to some embodiments of the present application, the width of the notch on the first edge gradually decreases in the direction from the first edge to the second edge, and / or the width of the notch on the second edge gradually decreases in the direction from the second edge to the first edge.
[0020] According to some embodiments of the present application, multiple notches are provided on the first edge and the second edge, the adjacent notches on the first edge are arranged at intervals, the adjacent notches on the second edge are arranged at intervals, and the notches on the first edge and the second edge are arranged one by one in correspondence with the width direction of the positive plate.
[0021] According to some embodiments of the present application, the area of a single notch is 0.1mm 2 to 5mm 2The number of the gaps is in the range of 1 to 400, and / or the total number of the gaps on the N positive electrode sheets is in the range of 1 to 400.
[0022] The electric core according to the second aspect of the present application comprises:
[0023] N+1 negative electrode sheets, N being a positive integer greater than or equal to 1;
[0024] N positive electrode sheets according to any one of the above embodiments;
[0025] The positive electrode sheets and the negative electrode sheets are alternately stacked to form the electric core, and the total number M of the gaps on the N positive electrode sheets has the following relationship: N≤M≤5N.
[0026] The electric core according to the third aspect of the present application comprises:
[0027] A negative electrode sheet;
[0028] A positive electrode sheet according to any one of the above embodiments;
[0029] The positive electrode sheet and the negative electrode sheet are wound for N times to form the electric core, N being a positive integer greater than 1 and equal to 1, and the total number M of the gaps on the positive electrode sheet has the following relationship: 2N≤M≤10N.
[0030] The battery according to the fourth aspect of the present application comprises:
[0031] A shell;
[0032] An electric core according to any one of the above embodiments, which is arranged in the shell.
[0033] Additional aspects and advantages of the present application will be given in part in the following description, become apparent from the following description, or be understood by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS
[0034] The present application will be further described below in combination with the drawings and embodiments, wherein:
[0035] Figure 1 A structure diagram of the positive electrode sheet of the embodiment of the present application (the gap on the first edge is a triangle);
[0036] Figure 2 A structure diagram of the positive electrode sheet of the embodiment of the present application (the gaps on the first edge and the second edge are both triangles);
[0037] Figure 3 A structure diagram of the positive electrode sheet of the embodiment of the present application (only one arc-shaped gap is arranged on the first edge and the second edge);
[0038] Figure 4 A structure schematic view of the positive plate of the embodiment of the present application (the notch on the first edge and the second edge are both semicircular shapes);
[0039] Figure 5 A structure schematic view of the positive plate of the embodiment of the present application (the notch on the first edge and the second edge are both trapezoidal shapes).
[0040] Reference signs:
[0041] Current collector 100; coating layer 200; first edge 300; second edge 400; notch 500; DETAILED DESCRIPTION
[0042] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary, and are only used to explain the present application, and cannot be understood as a limitation of the present application.
[0043] In the description of the present application, it should be understood that, in relation to the orientation description, for example, the orientation or position relationship indicated by the upper, lower, front, rear, 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 indicated 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.
[0044] In the description of the present application, the meaning of several is more than one, the meaning of multiple is more than two, greater than, less than, more than, etc. are understood as not including the number, above, below, etc. are 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.
[0045] 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 scheme.
[0046] In the description of the utility model, the description of the reference terms "one embodiment", "some embodiments", "illustrative embodiment", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the utility model. In the specification, the illustrative 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 one or more embodiments or examples in a suitable manner.
[0047] Lithium ion battery, also known as lithium battery, is a kind of secondary battery relying on lithium ion moving between positive and negative to achieve charging and discharging. Under the background of the rapid development of electric vehicles, electric light vehicles, electric tools, consumer electronics and new energy storage industries, lithium battery has been widely used in the market due to its advantages of high energy density, high discharge power, long cycle life, no memory effect and green environmental protection.
[0048] However, with the wide application of lithium ion battery, some technical problems have gradually emerged. In the charging and discharging process of lithium ion battery, especially in the area close to the side of the tab, the current of the charging and discharging process is relatively large. In the case of high rate charging, this large current is easy to cause lithium precipitation in the edge area of the battery. Lithium precipitation refers to that when the CB value (the ratio of the capacity of the negative electrode to the capacity of the positive electrode in the lithium ion battery) of the battery is small, the negative electrode does not have enough space to accommodate the lithium ions detached from the positive electrode, resulting in the precipitation of lithium ions on the surface of the negative electrode. Lithium precipitation not only affects the capacity and performance of the battery, but also may pose a threat to the safety of the battery.
[0049] To solve the above problems, the application provides a positive electrode sheet, which comprises a current collector 100 and a coating layer 200. The current collector 100 is made of metal foil material. Conventionally, the positive electrode sheet usually adopts aluminum foil material. In other embodiments, the positive electrode sheet can also be made of other metal foil materials or composite foil materials. In the electrode sheet manufacturing process, the current collector 100 is uniformly coated with a layer of positive electrode slurry on one side or both sides of its thickness direction. The slurry is mainly composed of positive electrode active material, conductive agent and adhesive, etc. After drying, cold pressing and other steps, the coating layer 200 is formed. After the coating layer 200 reacts with the electrolyte, lithium ions are precipitated, which can pass through the diaphragm and be embedded in the negative electrode material. It can be understood that the coating layer 200 can be formed on one side of the current collector 100 along its thickness direction, or on both sides of the current collector 100 along its thickness direction.
[0050] For ease of description, the two parallel edges on the positive electrode are named the first edge 300 and the second edge 400. It should be noted that the first edge 300 and the second edge 400 are distinguished by the location of the tabs. Specifically, the electrode often includes tabs (not shown in the figure). The coating layer 200 has tab grooves for exposing the current collector 100. These tab grooves are often located at the edge of the electrode. One end of the tab is placed in the tab groove and welded to the current collector 100. The other end of the tab extends outwards from the positive electrode and extends beyond the current collector 100 via the first edge 300. Alternatively, the tabs can be attached to the empty foil area at one end of the electrode, also extending beyond the current collector 100 via the first edge 300.
[0051] It should be noted that, depending on the manufacturing process, battery cells are often divided into laminated cells and wound cells. Laminated cells are formed by stacking multiple independent positive and negative electrode sheets, while wound cells are formed by winding a strip of negative electrode material and a strip of positive electrode material. For example... Figure 1 Taking the positive electrode sheet for winding a battery cell as an example, the first edge 300 and the second edge 400 are the two sides of the positive electrode sheet along its width direction, and the edge with the tab is the first edge 300. For a laminated battery cell, the first edge 300 and the second edge 400 can be the two sides along the width direction of the electrode sheet or the two sides along the length direction of the electrode sheet. Taking the edge with the tab as the first edge 300, the second edge 400 is the edge parallel to and opposite to the first edge 300.
[0052] Based on the foregoing, the side of the positive electrode sheet with the tab is prone to generating a large current, which can lead to lithium plating. Therefore, in this embodiment, at least one notch 500 is formed on the first edge 300, the notch 500 penetrating the current collector 100 and the coating layer 200. It is understood that after the positive electrode sheet is manufactured, the notch 500 can be formed on the first edge 300 by using equipment such as a die-cutting machine, or alternatively, an active material layer can be coated onto the current collector 100 where the notch 500 has already been formed, thus leaving the notch 500 uncoated.
[0053] It is understood that the positive electrode in this embodiment reduces the area and amount of active material by opening a notch 500 on the edge, thereby reducing the amount of lithium ions deposited on the positive electrode during the electrochemical reaction, especially the amount of lithium ions deposited at the edge of the positive electrode. By increasing the local CB at the edge of the electrode, the problem of lithium deposition at the edge of the electrode during high-rate charging is improved.
[0054] In some embodiments, the number of the notch 500 is one, for example, Figure 3The notch 500 shown can be an arc-shaped notch with a small curvature, or it can be a notch 500 of other shapes. The relationship between the area S of the projected region of the notch 500, the length L of the coating layer 200, and the width W of the coating layer 200, projected along the thickness direction of the positive electrode sheet, is as follows: 0.1% × L × W ≤ S ≤ 1% × L × W. In other embodiments, the number of notches 500 can also be multiple; for example, the notch 500 can be as follows... Figure 1 Or, as shown in triangle 2, multiple triangular notches 500 are evenly spaced along the first edge 300. The relationship between the total area S of the projected region of the multiple notches 500, the length L of the coating layer 200, and the width W of the coating layer 200, projected along the thickness direction of the positive electrode sheet, is as follows: 0.1% × L × W ≤ S ≤ 1% × L × W. It can be understood that when the area of the notches 500 and the area of the coating layer 200 have the above relationship, the probability of lithium plating during battery charging and discharging can be significantly reduced while ensuring that the energy density of the battery is not significantly affected.
[0055] It should be noted that in some embodiments, the length and width of the coating layer 200 may be the same as the length and width of the current collector 100, so the relationship between the projected area of the notch 500 and the projected area of the electrode sheet also applies to the above-mentioned relationship. In other embodiments, the width of the coating layer 200 may be the same as the width of the current collector 100, but empty foil areas are provided at both ends of the current collector 100, so the length of the coating layer 200 is less than the length of the current collector 100. Therefore, the area of the coating layer 200 needs to be used as a comparison benchmark to design the size and / or number of the notch 500.
[0056] In some embodiments, reference Figure 3 As shown, there is only one gap of 500, which can be any of the following shapes: triangle, arc, rectangle, or trapezoid. (Reference) Figure 2 , Figure 4 and Figure 5 As shown, in some other embodiments, there are multiple notches 500, and all notches 500 can be any one of triangles, arcs, rectangles, and trapezoids. Alternatively, the shapes of the notches 500 can be different, and the multiple notches 500 can be combinations of various shapes such as triangles, arcs, rectangles, and trapezoids. Figure 2 and Figure 4 As shown, when the notch 500 is triangular or arc-shaped, the width of the notch 500 on the first edge 300 gradually decreases along the direction from the first edge 300 to the second edge 400. It should be noted that... Figure 4 The arc-shaped notch 500 in the middle is set as a semi-circular arc.
[0057] For the scenario that lithium is precipitated on both sides of the edge of the pole piece in some high-rate charging and discharging process, a notch 500 can be formed on the first edge 300 and the second edge 400, as shown in Figure 2 , Figure 4 and Figure 5 At least one notch 500 is formed on the second edge 400. The notch 500 on the second edge 400 can also be any one or a combination of triangle, arc, rectangle or trapezoid. When the notch 500 is a triangle or an arc, the width of the notch 500 on the second edge 400 gradually decreases in the direction from the second edge 400 to the first edge 300.
[0058] It can be understood that the shape of the notch 500 on the second edge 400 can be the same as or different from that of the notch 500 on the first edge 300. In the embodiment as shown in Figures 2 to 5 , the shape of the notch 500 on the second edge 400 is the same as that of the notch 500 on the first edge 300, and the notch 500 on the second edge 400 and the notch 500 on the first edge 300 are symmetrically arranged along the central axis of the pole piece. Specifically, as shown in Figure 2 , a plurality of notches 500 are formed on the first edge 300 and the second edge 400, the adjacent notches 500 on the first edge 300 are arranged at intervals, the adjacent notches 500 on the second edge 400 are arranged at intervals, and the notches 500 on the first edge 300 and the second edge 400 are arranged one by one corresponding to the width direction of the positive pole piece. It can be understood that the notch 500 on the first edge 300 and the second edge 400 keeps consistent in shape, which facilitates the processing of the notch 500, and the material removal at the notch 500 can be realized by a set of molds.
[0059] In some embodiments, the area of a single notch 500 is in the range of 0.1mm 2 to 5mm 2 . And / or, the number of notches 500 is in the range of 1 to 400. By limiting the size and number of notches 500, the impact of the arrangement of notches 500 on the energy density of the battery can be avoided.
[0060] The second aspect embodiment of the present application proposes an electric core, which comprises a negative pole piece and a positive pole piece mentioned in any one of the above embodiments. It can be understood that the electric core can also comprise a separator and the like. The electric core is a laminated core, which specifically comprises N+1 negative pole pieces and N positive pole pieces, N being a positive integer greater than or equal to 1. The positive pole pieces and the negative pole pieces are alternately and laminatedly arranged to form the electric core, for example, the negative pole piece, the positive pole piece, the negative pole piece, the positive pole piece and the negative pole piece are laminatedly arranged. In order to ensure the energy density of the electric core, the total number M of notches 500 on the N positive pole pieces has the following relationship: N≤M≤5N.
[0061] The third aspect embodiment of the present application provides another kind of battery cell, which is a winding battery cell, specifically comprising a negative electrode sheet and the positive electrode sheet mentioned in the above embodiments, the negative electrode sheet and the positive electrode sheet are wound N times to form the battery cell, N is a positive integer greater than or equal to 1, and the total number M of the notches 500 on the positive electrode sheet has the following relationship: 2N≤M≤10N.
[0062] The fourth aspect embodiment of the present application provides a battery, which comprises a shell and the battery cell of any one of the above embodiments, the battery cell is arranged in the shell, and the shell is also filled with an electrolyte, the battery cell is soaked in the electrolyte and can occur electrochemical reaction to charge or discharge.
[0063] The embodiments of the present application are described in detail above in combination with the drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge range of ordinary skilled in the art without departing from the purpose of the present application. In addition, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.
Claims
1. A positive electrode sheet, characterized by, include: current collector; A coating layer formed on at least one side of the current collector along its thickness direction; Specifically, the positive electrode sheet has two parallel edges, namely the first edge and the second edge. The positive electrode sheet also includes a tab, which is connected to the current collector and extends out of the current collector via the first edge. At least one notch is provided on the first edge, and the notch penetrates the current collector and the coating layer.
2. The positive electrode sheet according to claim 1, characterized by The number of notches is one. The relationship between the area S of the notch projection region, the length L of the coating layer, and the width W of the coating layer along the thickness direction of the positive electrode sheet is as follows: 0.1% × L × W ≤ S ≤ 1% × L × W; Alternatively, the number of notches may be multiple, and the relationship between the total area S of the projected region of the multiple notches, the length L of the coating layer, and the width W of the coating layer along the thickness direction of the positive electrode sheet is as follows: 0.1% × L × W ≤ S ≤ 1% × L × W.
3. The positive electrode sheet according to claim 1, characterized by The number of the notch is one, and the notch can be any one of the following: triangle, arc, rectangle, and trapezoid. Alternatively, the number of the notches may be multiple, and the notches may be any one or a combination of the triangles, arcs, rectangles and trapezoids.
4. The positive electrode sheet according to claim 1, characterized by At least one notch is provided on the second edge.
5. The positive electrode sheet according to claim 4, characterized by Along the direction from the first edge to the second edge, the width of the notch on the first edge gradually decreases, and / or, along the direction from the second edge to the first edge, the width of the notch on the second edge gradually decreases.
6. The positive electrode sheet according to claim 1, characterized by Multiple notches are provided on both the first edge and the second edge. Adjacent notches on the first edge are spaced apart, and adjacent notches on the second edge are spaced apart. Furthermore, the notches on the first edge and the second edge are arranged in a one-to-one correspondence along the width direction of the positive electrode sheet.
7. The positive electrode sheet according to claim 1, characterized by The area of a single said gap is in the range of 0.1 mm 2 to 5 mm 2 and / or the number of said gaps is in the range of 1 to 400.
8. An electric cell, characterized by include: There are N+1 negative electrode plates, where N is a positive integer greater than or equal to 1; N positive electrode plates as described in any one of claims 1 to 7; The positive electrode and the negative electrode are alternately stacked to form the battery cell, and the total number M of the notches on the N positive electrode has the following relationship: N≤M≤5N.
9. An electric cell, characterized by include: Negative electrode plate; The positive electrode sheet as described in any one of claims 1 to 7; The positive electrode and the negative electrode are wound N turns to form the battery cell, where N is a positive integer greater than or equal to 1. The total number M of the notches on the positive electrode has the following relationship: 2N≤M≤10N.
10. A battery characterized by include: case; The battery cell as described in claim 8 or 9, wherein the battery cell is disposed in the housing.