Electrode plate and battery cell

Abstract

Electrode plate with a current collector (1) and active material layers (2), wherein the active material layers (2) are arranged on two opposite sides of the current collector (1), wherein one of the active material layers (2) located on one side has a first groove (21) and one of the active material layers (2) located on the other side has a second groove (22), wherein the groove bottoms of the first groove (21) and the second groove (22) each extend to the current collector (1), wherein a tab (3) is inserted into each of the first groove (21) and the second groove (22), wherein two tabs (3) are each connected to the current collector (1), and wherein the two tabs (3) are connected to each other.

Description

This application claims priority to Chinese patent application No. 2023201893728, filed with the Chinese Patent Office on February 8, 2023, the entire contents of which are incorporated into this application by reference. TECHNICAL FIELD This application relates to the technical field of battery cells, for example to an electrode plate and a battery cell. STATE OF THE ART With the rapid development of battery cell technology, people have put forward higher requirements for the energy density, discharge rate and discharge temperature increase of lithium-ion battery cells. Currently, in the production of electrode plates, a single tab is often welded to one side of the current collector, and the battery cell is formed by winding two electrode plates with opposite polarity and a separator. This technology has the following technical defects: the internal resistance of the battery cell with a single tab is very large and generates large heat during fast charging, which affects the service life and safety performance of the battery cell. DISCLOSURE OF THE INVENTION The present application provides an electrode plate with a simple structure and good safety performance. The present application provides a battery cell with a simple structure and a small thickness. The embodiments of the present application adopt the following technical solutions: In a first aspect, embodiments of the present application provide an electrode plate comprising a current collector and active material layers, wherein the active material layers are arranged on two opposite sides of the current collector, wherein one of the active material layers lying on one side has a first groove and one of the active material layers lying on the other side has a second groove, wherein the groove bottoms of the first groove and the second groove can each penetrate to the current collector, wherein a tab is inserted into each of the first groove and the second groove, wherein the two tabs are connected to the current collector, and wherein the two tabs are connected to each other. In one embodiment, it is provided that the two tabs are connected to each other via a current collecting piece. In one embodiment, it is provided that the respective tab comprises a metal plate and an insulating adhesive provided on the outer circumference of the metal plate, wherein the two metal plates are respectively inserted into the first groove and the second groove, and wherein the two metal plates are connected to one another via the current collecting piece, wherein two insulating adhesives are arranged next to one another along a first direction, wherein the first direction is a longitudinal direction in which the electrode plate extends. In one embodiment, it is provided that the first groove and the second groove are arranged opposite one another, wherein the size of the first groove and the second groove along the first direction is greater than or equal to twice the size of the insulating adhesive along the first direction; or Projections of the first groove and the second groove onto the current collector along the first direction are arranged side by side, wherein the size of the first groove and the second groove along the first direction is larger than the size of the insulating adhesive along the first direction. In one embodiment, it is provided that the size of the electrode plate fulfills at least one of the following conditions: a thickness of the active material layer is in the range of 0.05 to 0.2 mm; a thickness of the tab is in the range of 0.1 to 0.7 mm; a thickness of the insulating adhesive is in the range of 0.05 to 0.3 mm. In one embodiment, it is provided that the first groove and the second groove can penetrate at least one end of the active material layer along the width direction in the extension of the electrode plate. In one embodiment, it is provided that the first groove and the second groove are located at a position which is not an end position in the longitudinal direction in the extension of the electrode plate. In a second aspect, embodiments of the present application provide a battery cell, wherein the battery cell is formed from a separator and a positive electrode plate and a negative electrode plate located on both sides of the separator by wrapping, wherein the positive electrode plate and the negative electrode plate are the above-mentioned electrode plates. In one embodiment, it is provided that one of the positive electrode plate and the negative electrode plate is provided with a first groove of the electrode plate and a second groove of the electrode plate, and the other of the positive electrode plate and the negative electrode plate is each provided with a first escape groove at a position opposite the first groove and a second escape groove at a position opposite the second groove, wherein after the battery cell is wound up, a receiving space for receiving the tab of the electrode plate is formed between the first escape groove and the first groove, which are opposite to each other, and between the second escape groove and the second groove, which are opposite to each other. In one embodiment, it is provided that the thickness of the tab is less than or equal to the size of the receiving space along the second direction. The advantageous effect of the present application is that the active material layer is provided with a groove on the two opposite sides of the current collector, wherein a tab is welded into each of the two grooves, wherein the two tabs are connected to the current collector and the two tabs are connected to each other, thereby forming an electrode plate with a two-tab structure in which a tab is welded to each of the two sides of the current collector, wherein the electrode plate with a two-tab structure promotes current conduction, thereby effectively reducing the internal resistance of the battery cell, reducing the heat generated during rapid charging of the battery cell, and effectively improving the cycle life and safety performance of the battery cell. PRESENTATION OF THE INVENTION Fig. 1 is a schematic structural diagram of the electrode plate according to an embodiment of the present application; Fig. 2 is a schematic diagram of the cooperation between the current collector and the active material layer according to an embodiment of the present application; Fig. 3 is a schematic structural diagram of the battery cell according to an embodiment of the present application; Fig. 4 is a schematic diagram of the cooperation between the positive electrode plate, the negative electrode plate, and the separator according to an embodiment of the present application; In the drawings: 1. Current collector; 2. Active material layer; 21. First groove; 22. Second groove; 23. First escape groove; 24. Second escape groove; 3. Tab; 31. Metal plate; 32. Insulating adhesive; 4. Current collecting piece; 5. Separator; 6. Positive electrode plate; 7. Negative electrode plate. CONCRETE EMBODIMENTS When describing the present application, it should be noted that, unless otherwise specified and limited, the terms "attachment," "connection," and "fastening" are to be understood broadly. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical or electrical connection; it may be a direct connection or an indirect connection via an intermediate medium; and it may be an internal communication between two elements or an interrelationship between two elements. One of ordinary skill in the art can understand the meanings of the above terms in the present application according to situations. In the present application, the first feature being "above" or "below" the second feature may include that the first and second features are in direct contact, or the first and second features are not in direct contact but are in contact via another feature between them. Furthermore, the first feature being "above," "on," and "above" the second feature may include that the first feature is directly above and diagonally above the second feature, or simply mean that the first feature has a higher plane than the second feature. The first feature being "below," "below," and "down" the second feature may include that the first feature is directly below and diagonally below the second feature, or simply mean that the first feature has a smaller plane than the second feature. 1 and 2, the electrode plate according to embodiments of the present application comprises a current collector 1 and active material layers 2, wherein the active material layers 2 are arranged on two opposite sides of the current collector 1, wherein one of the active material layers 2, which lies on one side, has a first groove 21 and one of the active material layers 2, which lies on the other side, has a second groove 22, wherein the groove bottoms of the first groove 21 and the second groove 22 can each penetrate through to the current collector 1, wherein a tab 3 is inserted into each of the first groove 21 and the second groove 22, wherein the tab 3 can be welded to the current collector 1 by laser welding, wherein the two tabs 3 are each connected to the current collector 1, and wherein the two tabs 3 are connected to one another.A tab 3 is welded to each of the two opposite sides of the current collector 1, and the two tabs 3 are connected to each other, thereby forming an electrode plate having a two-tab structure in which a tab is welded to each of the two sides of the current collector 1. The electrode plate having a two-tab structure promotes current conduction, thereby effectively reducing the internal resistance of the battery cell, reducing the heat generated during rapid charging of the battery cell, and effectively improving the cycle life and safety performance of the battery cell. It is worth noting that, as shown in Fig. 1, the first groove 21 and the second groove 22 are located at a position other than an end position in the longitudinal direction in the extension of the electrode plate (the longitudinal direction in the extension of the electrode plate is the X direction in Fig. 1 ), that is, the first groove 21 and the second groove 22 are located at positions other than the both ends of the active material layer 2 and may be 1 / 15, 1 / 5, 1 / 3, 1 / 2 or another position other than an end position of the active material layer along the X direction, without too many limitations here. In the present embodiment, as shown in Fig. 1, the two tabs 3 are connected to each other via the current collector 4. The current collector 4 increases the contact area of the two tabs 3 and improves the connection strength of the two tabs 3, thereby improving the current conductivity at the junction between the two tabs 3 and reducing heat generation during rapid charging and discharging of the tabs 3. Optionally, as shown in Fig. 1, the first groove 21 and the second groove 22 may penetrate at least one end of the active material layer 2 along the width direction in the extension of the electrode plate (the width direction in the extension of the electrode plate is the Y direction in Fig. 1 ), wherein the cleaning method of the first groove 21 and the second groove 22 may be laser cleaning, mechanical cleaning, or foam adhesive cleaning or the like, and there are no excessive restrictions here.In the present embodiment, the first groove 21 and the second groove 22 penetrate only one end of the active material layer 2 along the Y direction. The tab 3 inserted into each of the first groove 21 and the second groove 22 extends from the through end of the groove to the outside of the groove. The parts of the two tabs 3 extending outside the groove are then connected to each other by the current collecting piece 4. Meanwhile, the end of the first groove 21 and the second groove 22 that does not completely penetrate the Y direction can provide support for the tab 3 during welding, thereby improving the stability of welding the tab 3. In other embodiments, the first groove 21 and the second groove 22 can also completely penetrate both ends of the active material layer 2 along the Y direction. For example, as shown in Fig. 1, the tab 3 includes a metal plate 31 and an insulating adhesive 32 provided on the outer periphery of the metal plate 31, the two metal plates 31 being respectively inserted into the first groove 21 and the second groove 22, and the two metal plates 31 being connected to each other via the current collecting piece 4, with two insulating adhesives 32 being arranged side by side along a first direction X, the first direction being the X direction. In the present embodiment, the first groove 21 and the second groove 22 are arranged opposite each other, and the first groove 21 and the second groove 22 are arranged symmetrically with respect to the current collector 1, which facilitates the formation of the first groove 21 and the second groove 22 simultaneously during the production process, thereby facilitating production.The size of the first groove 21 and the second groove 22 along the X direction is greater than or equal to twice the size of the insulating adhesive 32 along the X direction, so that the insulating adhesives 32 of the two tabs 3 are arranged side by side along the X direction, thereby preventing the two insulating adhesives 32 from interfering with each other when the metal plates 31 of the two tabs 3 are inserted into the first groove 21 and the second groove 22, thereby ensuring the welding strength between the metal plate 31 and the current collector 1 and the connection strength between the metal plate 31 and the current collecting piece 4.In other embodiments, projections of the first groove 21 and the second groove 22 onto the current collector 1 are arranged side by side along the X direction, and the size of the first groove 21 and the second groove 22 along the X direction is slightly larger than the size of the insulating adhesive 32 along the X direction, and mutual interference of the two insulating adhesives 32 when welding the two metal plates 31 to the current collector 1 can also be avoided. Of course, if the thickness of the insulating adhesive 32 of the two tabs 3 is small, that is, when the projections of the two insulating adhesives 32 onto the current collector 1 overlap, the two insulating adhesives 32 located at the overlapping part of the projections are still spaced apart from each other, then the first groove 21 and the second groove 22 can be directly provided, which are slightly larger than the size of the metal plate 31 along the X direction. For example, as shown in Figs. 1 and 2, the thickness of the active material layer 2 is in the range of 0.05 to 0.2 mm; the thickness of the tab 3 is in the range of 0.1 to 0.7 mm; and the thickness of the insulating adhesive 32 is in the range of 0.05 to 0.3 mm. Note that the above-mentioned thickness direction is the thickness direction along the extension of the electrode plate (the thickness direction along the extension of the electrode plate is the Z direction in Fig. 1). The embodiments of the present application also provide a battery cell, and as shown in Fig. 3, the battery cell is formed of a separator 5 and a positive electrode plate 6 and a negative electrode plate 7 located on both sides of the separator 5 by wrapping, wherein the positive electrode plate 6 and the negative electrode plate 7 are the electrode plates according to any one of the above-mentioned embodiments. Optionally, as shown in Fig. 4, the positive electrode plate 6 is provided with a first groove 21 and a second groove 22, and the first groove 21 and the second groove 22 are each provided with tabs 3 on the inside, the two tabs 3 being connected to each other to form an entire tab on the positive electrode. At this time, the active material layer 2 is provided on the two opposite sides of the negative electrode plate 7, respectively, with a first escape groove 23 at a position opposite to the first groove 21 and a second escape groove 24 at a position opposite to the second groove 22. After winding, a receiving space for receiving the tab 3 of the positive electrode plate 6 is formed between the first escape groove 23 and the first groove 21, which are opposite to each other, and between the second escape groove 24 and the second groove 22, which are opposite to each other.By disposing the first escape groove 23 and the second escape groove 24 on the negative electrode plate 7, the tabs 3 of the positive electrode plate 6 protruding from the first groove 21 and the second groove 22 can be escaped when the positive electrode plate 6 and the negative electrode plate 7 are wound into a battery cell, whereby the increase in thickness caused by the tabs 3 can be reduced, thereby reducing the thickness of the battery cell and increasing the overall energy density of the battery cell.In addition, when the first groove 21 and the second groove 22 are formed on the negative electrode plate 7, the first escape groove 23 and the second escape groove 24 are provided on the positive electrode plate 6 to escape the tabs 3 on the negative electrode plate 7, thereby avoiding the problem of the thickness difference caused by the tabs 3 protruding from the active material layer 2, and improving the flatness of the battery cell. Optionally, as shown in Fig. 3, the thickness of the tab 3 is less than or equal to the size of the receiving space along the second direction (the second direction is the thickness direction in the extension of the electrode plate, i.e., the Z direction in Fig. 1 ), where the Z direction is perpendicular to the X direction, that is, the tab 3 can be completely received in the receiving space, thereby effectively improving the thickness difference of the battery cell at this position and improving the flatness of the battery cell. By way of example, the electrode plate also includes an adhesive paper, wherein the parts of the tab 3 exposed after welding are each covered with adhesive paper, whereby the burrs of the tab 3 can be prevented from penetrating the separator 5 and causing an internal short circuit of the battery cell, and wherein the insulation between the electrode plates can be improved, thereby ensuring the service life and safety performance of the battery cell. In describing the present application, it should be understood that the terms "top", "bottom", and like orientations or positional relationships are the orientations or positional relationships shown based on the drawings and are used only for convenience of description and ease of operation, rather than stating or implying that the said device or element must have a particular orientation or be constructed and operated in a particular orientation, and therefore should not be construed as limiting the present application.

Claims

Electrode plate with a current collector (1) and active material layers (2), wherein the active material layers (2) are arranged on two opposite sides of the current collector (1), wherein one of the active material layers (2) lying on one side has a first groove (21) and one of the active material layers (2) lying on the other side has a second groove (22), wherein groove bottoms of the first groove (21) and the second groove (22) each penetrate through to the current collector (1), wherein a tab (3) is inserted into each of the first groove (21) and the second groove (22), wherein two tabs (3) are each connected to the current collector (1), and wherein the two tabs (3) are connected to one another. Electrode plate according to claim 1, wherein the two tabs (3) are connected to each other via a current collecting piece (4). Electrode plate according to claim 2, wherein the respective tab (3) comprises a metal plate (31) and an insulating adhesive (32) provided on the outer circumference of the metal plate (31), wherein both two metal plates (31) are respectively inserted into the first groove (21) and the second groove (22), and wherein the two metal plates (31) are connected to each other via the current collecting piece (4), wherein two insulating adhesives (32) are arranged next to each other along a first direction (X), wherein the first direction (X) is a longitudinal direction in which the electrode plate extends. Electrode plate according to claim 3, wherein the first groove (21) and the second groove (22) are arranged opposite one another, wherein a size of the first groove (21) and a size of the second groove (22) along the first direction (X) is greater than or equal to twice a size of the insulating adhesive (32) along the first direction (X); or wherein projections of the first groove (21) and the second groove (22) onto the current collector (1) along the first direction (X) are arranged side by side, wherein the size of the first groove (21) and the size of the second groove (22) along the first direction (X) is greater than the size of the insulating adhesive (32) along the first direction (X). Electrode plate according to claim 3 or 4, wherein the size of the electrode plate satisfies at least one of the following conditions: a thickness of the active material layer (2) is in the range of 0.05 mm to 0.2 mm; a thickness of the tab (3) is in the range of 0.1 mm to 0.7 mm; a thickness of the insulating adhesive (32) is in the range of 0.05 mm to 0.3 mm. Electrode plate according to one of claims 1 to 4, wherein the first groove (21) and the second groove (22) penetrate at least one end of the active material layers (2) along a width direction in the extension of the electrode plate. Electrode plate according to one of claims 1 to 4, wherein the first groove (21) and the second groove (22) are located at a position which is not an end position in a longitudinal direction in the extension of the electrode plate. A battery cell formed from a separator (5) and a positive electrode plate (6) and a negative electrode plate (7) located on both sides of the separator (5) by wrapping, wherein the positive electrode plate (6) and the negative electrode plate (7) are the electrode plate according to any one of claims 1 to 7. Battery cell according to claim 8, wherein one of the positive electrode plate (6) and the negative electrode plate (7) is provided with the first groove (21) of the electrode plate and the second groove (22) of the electrode plate, and the other of the positive electrode plate (6) and the negative electrode plate (7) is each provided with a first escape groove (23) at a position opposite the first groove (21) and a second escape groove (24) at a position opposite the second groove (22), wherein after the battery cell is wound up, a receiving space for receiving the tab (3) of the electrode plate is formed between the first escape groove (23) and the first groove (21), which are opposite to each other, and between the second escape groove (24) and the second groove (22), which are opposite to each other. Battery cell according to claim 9, wherein the thickness of the tab (3) is less than or equal to a size of the receiving space along a second direction (Z).

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