Electrode sheet and battery

Abstract

The present application relates to the technical field of battery energy, and in particular to an electrode sheet and a battery. The electrode sheet comprises a current collector, a tab, and a first active layer. One surface of the current collector is coated with the first active layer, and the first active layer is provided with a first tab groove; the first active layer located outside the first tab groove is provided with accommodating portions, and openings of the accommodating portions on the first active layer are located on the side of the first active layer away from the current collector; the thicknesses of the first active layer at the positions of the accommodating portions are less than the thickness of the first active layer in a region where a non-accommodating portion is located; and the ratio of the minimum thickness of the first active layer at the positions of the accommodating portions to the thickness of the first active layer in the region where the non-accommodating portion is located ranges from 0.3 to 0.7. Lithium ions can be more quickly and easily intercalated in an active layer near a current collector by means of accommodating portions, thereby enhancing the kinetic performance of a battery, reducing the current density in a region near a tab groove, and mitigating lithium plating in the region near the tab groove.

Description

A pole piece and a battery

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 27, 2023, with application number 202323601615.3 and application name “A Pole and Battery”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery energy technology, and in particular to a pole piece and a battery. Background Art

[0003] Lithium-ion batteries, with their high energy density and fast charging speed, have become the most widely used secondary battery. With the rapid development of electronic products, there is a growing demand for lithium-ion batteries that provide energy for these products.

[0004] Currently, batteries consist of stacked pole pieces, each comprising a current collector, an active layer coated on the current collector, and a tab welded to the current collector. Tab slots are provided in the active layer, exposing the portion of the current collector located within the tab slots. The tabs are welded to the current collector within the tab slots. To reduce the battery's internal resistance and temperature rise, the tabs are welded to the center of the pole piece.

[0005] However, during high-rate charging of the battery, lithium deposition is prone to occur in the area of ​​the electrode near the tab slot, affecting the battery's cycle performance.

[0006] Summary of the Invention

[0007] In order to solve the problems mentioned in the background technology, the embodiments of the present application provide a pole piece and a battery, in which lithium ions can be more quickly and easily embedded in the active layer close to the current collector side, thereby enhancing the dynamic performance of the battery, reducing the current density in the area near the pole tab slot, and alleviating lithium plating in the area near the pole tab slot.

[0008] In order to achieve the above-mentioned object, a first aspect of an embodiment of the present application provides a pole piece, comprising a current collector, a pole tab and a first active layer;

[0009] The first active layer is coated on one side of the current collector, and a first tab groove is provided on the first active layer;

[0010] One end of the tab extends into the first tab slot and is electrically connected to the current collector;

[0011] The first active layer located outside the first tab groove is provided with an accommodation portion, and the opening of the accommodation portion on the first active layer is located on a side of the first active layer away from the current collector;

[0012] The thickness of the first active layer at the location of the accommodation portion is smaller than the thickness of the first active layer in the area where the non-accommodation portion is located;

[0013] The ratio of the minimum thickness of the first active layer at the location of the accommodation portion to the thickness of the first active layer in the area where the accommodation portion is not located is in a range of 0.3-0.7.

[0014] In one possible implementation, the electrode sheet further includes a second active layer, which is coated on a side of the current collector facing away from the first active layer. An accommodating portion is also provided in an area of ​​the second active layer corresponding to the first electrode tab groove, and an opening of the accommodating portion on the second active layer is located on a side of the second active layer facing away from the current collector.

[0015] The thickness of the second active layer at the location of the accommodation portion is smaller than the thickness of the second active layer in the region where the accommodation portion is not located.

[0016] In a possible implementation, the second active layer is provided with a second tab groove facing the first tab groove, and the accommodation portion on the second active layer is located outside the second tab groove.

[0017] In a possible implementation, a projection of the second active layer in the third direction covers the first tab groove, and an accommodating portion is provided in a region of the second active layer facing the first tab groove.

[0018] In a possible implementation, the accommodation portion is a groove.

[0019] In a possible implementation, the width of the groove gradually decreases from the opening toward the current collector.

[0020] In a possible implementation manner, the groove extends along the second direction.

[0021] In a possible implementation, the total thickness of the first active layer is 50 μm-150 μm; and / or,

[0022] The depth of the accommodation portion on the first active layer is 10 μm-50 μm; and / or,

[0023] The width of the opening of the receiving portion is 50 μm to 200 μm.

[0024] In a possible implementation, there are multiple accommodating portions on the first active layer, and the multiple accommodating portions are arranged at intervals on the first active layer, and the multiple accommodating portions are arranged around the first tab slot.

[0025] In a possible implementation, in the first direction, the maximum distance between the edge of the opening of the first active layer where the accommodation portion is provided and the first tab groove is in a range of 1 mm to 10 mm; and / or,

[0026] In the second direction, a maximum distance between an edge of the opening of the first active layer where the accommodation portion is provided and the first tab groove is in a range of 1 mm to 10 mm.

[0027] In a possible implementation, the interval between two adjacent accommodation portions on the first active layer ranges from 100 μm to 2000 μm.

[0028] In a possible implementation, a first protective layer is provided on a side of the first active layer facing away from the current collector, and a projection of the first protective layer in the third direction covers a projection of the first tab groove in the third direction.

[0029] In a possible implementation, in the first direction, there is a first gap between the first tab slot and the adjacent accommodation portion; and / or,

[0030] In the second direction, a second gap is provided between the first tab groove and the accommodating portion facing the first tab groove.

[0031] In a possible implementation, the first gap ranges from 5 μm to 50 μm; and / or,

[0032] The second gap ranges from 5 μm to 50 μm.

[0033] In a possible implementation, a second protective layer is provided on a side of the second active layer facing away from the current collector, and a projection of the second protective layer in the third direction covers a projection of the second tab groove in the third direction.

[0034] In a possible implementation, the second active layer is provided with a second tab groove facing the first tab groove, and the accommodation portion on the second active layer is located outside the second tab groove.

[0035] In a possible implementation, a projection of the second active layer in the second direction covers the first tab groove, and an accommodating portion is further provided in a region of the second active layer facing the first tab groove.

[0036] A second aspect of the embodiments of the present application further provides a battery comprising the above-mentioned electrode.

[0037] The present application provides a pole piece and a battery, which includes a current collector, a pole tab, and a first active layer, wherein the first active layer is provided with a first pole tab groove. The first active layer located outside the first pole tab groove is provided with a receiving portion, and the thickness of the first active layer at the receiving portion is less than the thickness of the first active layer in the area where the receiving portion is not located. The receiving portion on the first active layer can store electrolyte. In the area where the first active layer is provided with the receiving portion, part of the distance that lithium ions originally diffused on the first active layer is converted to diffusion of electrolyte in the receiving portion. Compared with the first active layer, lithium ions are more easily diffused in the electrolyte. Moreover, lithium ions can diffuse from the sidewalls of the receiving portion to the area of ​​the first active layer where the receiving portion is not provided. That is, lithium ions can be more quickly and easily embedded in the active layer near the current collector, thereby enhancing the dynamic performance of the battery, reducing the current density in the area near the pole tab groove, and alleviating lithium plating in the area near the pole tab groove. In addition, the ratio of the minimum thickness of the first active layer at the accommodating portion to the thickness of the first active layer in the area where the non-accommodating portion is located is in the range of 0.3-0.7, which ensures that the accommodating portion improves the lithium deposition of the first active layer in the area near the tab groove while also ensuring the first active layer's ability to accommodate lithium ions at the accommodating portion.

[0038] In addition to the technical problems solved by the embodiments of the present application, the technical features that constitute the technical solutions, and the beneficial effects brought about by the technical features of these technical solutions described above, other technical problems that can be solved by the batteries and electronic devices provided by the embodiments of the present application, other technical features included in the technical solutions, and the beneficial effects brought about by these technical features will be further described in detail in the specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0040] FIG1 is a cross-sectional view of a pole piece according to an embodiment of the present application;

[0041] FIG2 is a second cross-sectional view of a pole piece provided in an embodiment of the present application;

[0042] FIG3 is a schematic structural diagram of a single-pole tab electrode provided in an embodiment of the present application;

[0043] FIG4 is a schematic diagram of a first protective layer provided in an embodiment of the present application disposed on the electrode shown in FIG3 ;

[0044] FIG5 is a schematic diagram of the structure of a multi-electrode pole piece provided in an embodiment of the present application;

[0045] FIG6 is a 3D microscope image of a receiving portion provided in an embodiment of the present application;

[0046] FIG7 is a SEM image of a pole piece at the location of a receiving portion provided in an embodiment of the present application;

[0047] FIG8 is a schematic diagram of the structure of a battery cell provided in an embodiment of the present application.

[0048] Description of reference numerals:

[0049] 100 - pole piece; 110 - first active layer; 111 - first pole tab slot; 120 - second active layer; 121 - second pole tab slot; 130 - current collector; 140 - pole tab; 150 - receiving portion; 160 - first protective layer;

[0050] 200-positive electrode;

[0051] 300-diaphragm. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below in conjunction with the drawings in the preferred embodiments of the present application. In the drawings, the same or similar reference numerals throughout represent the same or similar parts or parts with the same or similar functions. The described embodiments are part of the embodiments of the present application, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present application, and should not be understood as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The embodiments of the present application are described in detail below in conjunction with the drawings.

[0053] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to a fixed connection, an indirect connection via an intermediate medium, internal communication between two components, or an interaction between two components. Those skilled in the art will understand the specific meanings of these terms in this application based on specific circumstances.

[0054] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are orientations or positional relationships based on the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this application.

[0055] The terms "first", "second" and "third" (if any) in the description and claims of this application and the above drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0056] In addition, the terms "comprises" and "having" and any variations thereof are intended to cover a non-exclusive inclusion, for example, a process, method, system, product or display that includes a series of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, product or display.

[0057] In existing technology, a tab slot is defined in the active layer of the electrode sheet. One end of the tab extends into the slot and is electrically connected to the current collector. To reduce the battery's internal resistance and temperature rise, the tab is positioned centrally in the electrode sheet to enable high-rate charging. However, during high-rate charging, lithium deposition is prone to occur in the area of ​​the electrode sheet near the tab slot, impacting battery performance.

[0058] This is because when the battery is charged at a high rate, lithium ions cannot be quickly embedded in the area near the tab slot, which makes the area near the tab slot prone to lithium deposition.

[0059] In view of the above problems, an embodiment of the present application provides a pole piece and a battery, wherein a first active layer is coated on one side of a current collector, and a first pole tab groove is provided on the first active layer. A receiving portion is provided on the outside of the first pole tab groove of the first active layer. The thickness of the first active layer at the receiving portion is less than the thickness of the first active layer in the area where the receiving portion is not located. The receiving portion can store electrolyte, and part of the distance that lithium ions originally diffused on the first active layer is converted into electrolyte diffusion in the receiving portion. Compared with on the first active layer, lithium ions are more easily diffused in the electrolyte, and lithium ions can diffuse from the side wall of the receiving portion to the area of ​​the active layer where the receiving portion is not provided, that is, lithium ions can be more quickly and easily embedded in the side of the active layer close to the current collector, thereby enhancing the dynamic performance of the battery, reducing the current density in the area near the pole tab groove, alleviating lithium plating in the area near the pole tab groove, and facilitating high-rate charging of the battery. By setting the ratio between the minimum thickness of the first active layer at the accommodating portion and the thickness of the first active layer in the area where the non-accommodating portion is located, the improvement effect of the accommodating portion on the lithium deposition of the first active layer in the area near the tab groove is ensured, while the lithium ion accommodation capacity of the first active layer at the accommodating portion is ensured.

[0060] The following is a detailed description of the technical solutions of the electrode sheet and battery provided in the embodiments of the present application, with reference to the accompanying drawings. It should be noted that the first direction is the length direction of the electrode sheet, i.e., the direction indicated by the X-axis in Figures 1-5 ; the second direction is the width direction of the electrode sheet, i.e., the direction indicated by the Y-axis in Figures 1-5 ; and the third direction is the thickness direction of the electrode sheet, i.e., the direction indicated by the Z-axis in Figures 1-5 .

[0061] As shown in Figures 1 to 5, an electrode sheet 100 provided in an embodiment of the present application includes a current collector 130, a tab 140, and a first active layer 110. The first active layer 110 is coated on one side of the current collector 130 and is provided with a first tab groove 111. One end of the tab 140 extends into the first tab groove 111 and is electrically connected to the current collector 130. An accommodating portion 150 is provided on the first active layer 110 outside the first tab groove 111. The opening of the accommodating portion 150 is located on the side of the first active layer 110 facing away from the current collector 130. The thickness of the first active layer 110 at the accommodating portion 150 is less than the thickness of the first active layer 110 in the area not containing the accommodating portion 150. The ratio between the minimum thickness of the first active layer 110 at the accommodating portion 150 and the thickness of the first active layer 110 in the area not containing the accommodating portion 150 is in the range of 0.3-0.7.

[0062] The electrode sheet 100 may be a negative electrode sheet, and copper foil may be used as the current collector 130. For example, a first electrode tab groove 111 may be formed on the first active layer 110 by laser cleaning, and the electrode sheet 100 may expose the current collector 130 at the location of the first electrode tab groove 111. After the end of the electrode tab 140 extends into the first electrode tab groove 111, it may be secured to the current collector 130 by welding to achieve electrical connection between the electrode tab 140 and the current collector 130.

[0063] In a possible implementation, the accommodation portion 150 may be formed on the first active layer 110 by laser etching. After laser etching, the thickness of the first active layer 110 at the location of the accommodation portion 150 is smaller than the thickness of the first active layer 110 at the location of the non-accommodation portion 150.

[0064] It is worth mentioning that the number of the tabs 140 can be one or more. When the number of the tabs 140 is more than one, the number of the first tab slots 111 is the same as the number of the tabs 140 , and the end of each tab 140 extends into the corresponding first tab slot 111 .

[0065] For example, the ratio of the minimum thickness of the first active layer 110 at the location of the accommodation portion 150 to the thickness of the first active layer 110 in the area where the non-accommodation portion 150 is located can be 0.3, 0.4, 0.5, 0.6, or 0.7, etc., which is not limited here. When the ratio of the minimum thickness of the first active layer 110 at the location of the accommodation portion 150 to the thickness of the first active layer 110 in the area where the non-accommodation portion 150 is located is less than 0.3, the accommodation portion 150 has little effect on improving lithium deposition on the first active layer 110 near the tab groove; when the ratio of the minimum thickness of the first active layer 110 at the location of the accommodation portion 150 to the thickness of the first active layer 110 in the area where the non-accommodation portion 150 is located is greater than 0.7, the thickness of the first active layer 110 at the location of the accommodation portion 150 is too small, and the first active layer 110 at the location of the accommodation portion 150 is insufficient to accommodate lithium ions, resulting in lithium ion deposition at the location of the accommodation portion 150.

[0066] In the electrode sheet 100 provided in this embodiment, the first active layer 110 located outside the first tab groove 111 is provided with a receiving portion 150. The thickness of the first active layer 110 at the location of the receiving portion 150 is less than the thickness of the first active layer 110 in the area not including the receiving portion 150. The receiving portion 150 on the first active layer 110 can store electrolyte. In the area of ​​the first active layer 110 provided with the receiving portion 150, part of the distance that lithium ions would have diffused on the first active layer 110 is converted to diffusion of electrolyte in the receiving portion 150. Compared to the area on the first active layer 110, lithium ions diffuse more easily in the electrolyte. Lithium ions can also diffuse from the sidewalls of the receiving portion 150 to the area of ​​the first active layer 110 not provided with the receiving portion 150. In other words, lithium ions can more quickly and easily embed into the active layer near the current collector 130, thereby enhancing the battery's dynamic performance, reducing the current density in the area near the tab groove, and alleviating lithium deposition in this area. The ratio of the minimum thickness of the first active layer 110 at the position of the accommodating portion 150 to the thickness of the first active layer 110 in the area where the non-accommodating portion 150 is located is in the range of 0.3-0.7, which ensures that the accommodating portion 150 improves the lithium deposition of the first active layer 110 in the area near the pole ear groove while also ensuring the lithium ion accommodation capacity of the first active layer 110 at the position of the accommodating portion 150.

[0067] In addition, during the liquid injection process of the battery made of the electrode 100, the electrolyte can penetrate into the first active layer 110 near the electrode tab groove through the accommodating portion 150, that is, the accommodating portion 150 provides more paths for the penetration of the electrolyte, and the electrolyte can more easily penetrate the area of ​​the first active layer 110 near the electrode tab groove.

[0068] In one embodiment, as shown in Figures 1 and 2, the electrode sheet 100 further includes a second active layer 120, which is coated on a side of the current collector 130 facing away from the first active layer 110. An accommodating portion 150 is also provided in the region of the second active layer 120 corresponding to the first electrode tab groove 111. The opening of the accommodating portion 150 on the second active layer 120 is located on the side of the second active layer 120 facing away from the current collector 130. The thickness of the second active layer 120 at the location of the accommodating portion 150 is less than the thickness of the second active layer 120 in the region where the accommodating portion 150 is not located.

[0069] As will be appreciated, the pole piece 100 is coated on both sides of the current collector 130. Illustratively, the thickness of the second active layer 120 can be the same as that of the first active layer 110. Optionally, the accommodation portion 150 can be formed on the second active layer 120 by laser etching. After laser etching, the thickness of the second active layer 120 at the location of the accommodation portion 150 is less than the thickness of the second active layer 120 in the area where the accommodation portion 150 is located.

[0070] By forming the accommodation portion 150 on the second active layer 120, lithium ions can be more easily embedded into the area of ​​the second active layer 120 corresponding to the first pole tab groove 111 through the accommodation portion 150. The accommodation portion 150 on the second active layer 120 also provides more paths for the penetration of the electrolyte, making it easier for the electrolyte to penetrate the area of ​​the second active layer 120 corresponding to the first pole tab groove 111.

[0071] In a possible implementation, as shown in FIG. 1 , the second active layer 120 is provided with a second tab groove 121 facing the first tab groove 111 , and the accommodation portion 150 on the second active layer 120 is located outside the second tab groove 121 .

[0072] For example, a second tab groove 121 can be formed on the second active layer 120 by laser cleaning. Illustratively, the projection of the first tab groove 111 in the third direction, i.e., the direction indicated by the Z-axis, coincides with the projection of the second tab groove 121 in the third direction. Optionally, the projection of each accommodating portion 150 on the first active layer 110 in the third direction coincides with the projection of each accommodating portion 150 on the second active layer 120 in the third direction. The provision of the second tab groove 121 facilitates welding of the tab 140 to the current collector 130. The tab 140 can be secured to the current collector 130 using various welding methods, such as ultrasonic welding or laser welding.

[0073] In this structure, the accommodating portion 150 on the second active layer 120 is located on the outside of the second pole tab groove 121. The accommodating portion 150 on the second active layer 120 can alleviate lithium plating at a position of the second active layer 120 near the second pole tab groove 121. At the same time, the electrolyte can more easily penetrate the area of ​​the second active layer 120 near the second pole tab groove 121.

[0074] Optionally, a second protective layer is provided on a side of the second active layer 120 facing away from the current collector 130 , and a projection of the second protective layer in the third direction covers a projection of the second electrode tab groove 121 in the third direction.

[0075] Adhesive tape can be used as the second protective layer, which is applied to the second active layer 120 to cover the second tab groove 121. After the tab 140 is fixed to the current collector 130 by welding, the second protective layer is provided on the second active layer 120. The second protective layer can prevent the weld marks between the tab 140 and the current collector 130 from piercing the separator and causing a short circuit in the battery.

[0076] In one embodiment, as shown in FIG. 2 , the projection of the second active layer 120 in the third direction covers the first tab groove 111 , and an accommodating portion 150 is provided in a region of the second active layer 120 facing the first tab groove 111 .

[0077] That is, the projection of the second active layer 120 in the direction indicated by the Z axis covers the first tab groove 111, and the area of ​​the second active layer 120 facing the first tab groove 111 is active material. The above arrangement is conducive to improving the capacity of the battery made of the electrode sheet 100.

[0078] Optionally, an accommodating portion 150 is also provided on the outer side of the area of ​​the second active layer 120 facing the first tab groove 111. Exemplarily, a plurality of accommodating portions 150 are provided on the second active layer 120, and the plurality of accommodating portions 150 are arranged at equal intervals, and the projection of the first tab groove 111 in the second direction is located within the area of ​​the second active layer 120 where the accommodating portions 150 are provided.

[0079] Through the above configuration, the accommodating portion 150 on the area of ​​the second active layer 120 facing the first pole tab groove 111 can alleviate lithium plating at the position of the second active layer 120 facing the first pole tab groove 111. At the same time, the electrolyte can more easily penetrate the area of ​​the second active layer 120 facing the first pole tab groove 111.

[0080] In one embodiment, as shown in FIG. 1 to FIG. 6 , the receiving portion 150 is a groove.

[0081] Illustratively, the end of the groove on the first active layer 110 extends to the edge of the first active layer 110, and the end of the groove on the second active layer 120 extends to the edge of the second active layer 120. The grooves can be formed on the active layer by laser marking.

[0082] This structure, on the one hand, facilitates the processing of the accommodating portion 150 , and on the other hand, allows the electrolyte to flow from the end of the groove to the middle of the groove along the extension direction of the groove, further facilitating the electrolyte to penetrate the area of ​​the active layer close to the tab groove.

[0083] In other embodiments, the accommodating portion 150 may also be an accommodating hole, and the number of the accommodating holes may be one or more. When there are more than one accommodating holes, the multiple accommodating holes are respectively arranged on the first active layer 110 and the second active layer 120 .

[0084] In one possible implementation, as shown in Figures 1, 2, and 6, the width of the groove gradually decreases from the opening toward the current collector 130. In other words, the cross-section of the groove can be approximately V-shaped, and the groove is a tapered groove. This arrangement facilitates the formation of the groove on the first active layer 110 by laser marking.

[0085] In a specific embodiment, as shown in FIG. 3 to FIG. 5 , the groove extends along the second direction.

[0086] That is, the groove extends along the width direction of the pole piece 100, that is, the direction indicated by the Y axis in Figures 3 to 5. Extending the groove along the width direction of the pole piece 100 facilitates the processing of the groove.

[0087] Illustratively, the total thickness of the first active layer 110 is 50 μm-150 μm.

[0088] The thickness of the second active layer 120 can be the same as that of the first active layer 110. When the thickness of the first active layer 110 is less than 50 μm, the battery capacity of the electrode piece 100 is low. When the thickness of the first active layer 110 is greater than 150 μm, the battery volume of the electrode piece 100 is large, resulting in a lower energy density. With this configuration, the battery capacity and energy density are both guaranteed.

[0089] Optionally, the depth of the accommodation portion 150 on the first active layer 110 is 10 μm-50 μm.

[0090] For example, as shown in FIG6 , the depth of the accommodating portion 150 can be 22.57 μm. When the depth of the accommodating portion 150 is less than 10 μm, the accommodating portion 150 has little effect on improving the lithium deposition on the active layer near the tab groove; when the depth of the accommodating portion 150 is greater than 50 μm, the thickness of the first active layer 110 or the second active layer 120 at the position of the accommodating portion 150 is too small, and the active layer at the position of the accommodating portion 150 is insufficient to accommodate lithium ions, resulting in lithium ions being deposited at the position of the accommodating portion 150. The specific depth of the accommodating portion 150 can be set according to the battery charging rate and is not solely limited here. When testing the depth of the accommodating portion 150, a 3D microscope can be used to obtain a 3D microscope image of the first active layer 110 or the second active layer 120 where the accommodating portion 150 is provided, and the depth of the accommodating portion 150 can be obtained based on the 3D microscope image.

[0091] This structure ensures that the accommodation portion 150 improves lithium deposition in the area of ​​the active layer near the tab 140 .

[0092] In one possible implementation, as shown in Figure 7 , the width of the opening of the receiving portion 150 is 50 μm-200 μm. For example, the width of the opening of the receiving portion 150 can be 50 μm, 100 μm, 150 μm, 200 μm, etc., which is not limited here.

[0093] For example, the opening width of the accommodation portion 150 can be obtained using a scanning electron microscope. When the opening width of the accommodation portion 150 is less than 50 μm, the electrolyte stored in the accommodation portion 150 is relatively small, and the accommodation portion 150 has little effect on improving lithium deposition on the surface of the active layer near the tab groove. When the opening width of the accommodation portion 150 is greater than 200 μm, the active layer loses more active material near the tab groove, resulting in a significant reduction in battery capacity. Setting the opening width of the accommodation portion 150 to 50 μm-200 μm ensures that lithium deposition on the surface of the active layer near the tab groove can be effectively improved while also ensuring battery capacity.

[0094] In one embodiment, as shown in FIG. 1 to FIG. 5 , there are multiple accommodating portions 150 on the first active layer 110 . The multiple accommodating portions 150 are arranged at intervals on the first active layer 110 , and the multiple accommodating portions 150 are arranged around the first tab groove 111 .

[0095] For example, the plurality of accommodating portions 150 on the first active layer 110 can be arranged at equal intervals. For example, the dimension L1 of the area on the first active layer 110 where the accommodating portions 150 are provided in the length direction of the electrode piece 100 is 30 mm to 200 mm; and the dimension of the area on the first active layer 110 where the accommodating portions 150 are provided in the width direction of the electrode piece 100 is 20 mm to 200 mm.

[0096] For example, there may be a plurality of accommodation portions 150 on the second active layer 120 , and the plurality of accommodation portions 150 are arranged at equal intervals on the second active layer 120 .

[0097] This embodiment does not limit the specific number of the accommodating portions 150, and those skilled in the art can arrange it according to actual needs. In one possible implementation, the first tab slot 111 is provided with multiple accommodating portions 150 on opposite sides of the pole piece 100 in the length direction, and the first tab slot 111 is directly opposite the multiple accommodating portions 150 in the width direction of the pole piece 100.

[0098] In this embodiment, the number of the accommodating portions 150 is set to be multiple, which further facilitates the electrolyte to penetrate into the first active layer 110 near the tab groove, and further alleviates the lithium plating problem of the electrode 100 near the tab groove.

[0099] In a possible implementation, in the first direction, a maximum distance between an edge of the opening of the first active layer 110 where the accommodation portion 150 is provided and the first tab groove 111 is in a range of 1 mm to 10 mm.

[0100] Specifically, the maximum distance is the distance between the farthest edge of the opening of the first tab slot 111 and the first tab slot 111 in the first direction. When the maximum distance between the edge of the opening where the accommodating portion 150 is provided in the first active layer 110 and the first tab slot 111 is less than 1 mm, it indicates that each accommodating portion 150 is relatively close to the first tab slot 111 in the first direction, and lithium deposition may occur outside the region of the first active layer 110 where the accommodating portion 150 is provided in the first direction. When the maximum distance between the edge of the opening where the accommodating portion 150 is provided in the first active layer 110 and the first tab slot 111 is greater than 10 mm, it indicates that the accommodating portion 150 may be provided outside the region of the first active layer 110 where lithium deposition is likely to occur in the first direction, resulting in a significant loss of active material in the first active layer 110, which may affect the energy density of the battery fabricated from the electrode sheet 100. In other words, the above arrangement can ensure that the accommodating portion 150 improves lithium deposition in the first direction of the first active layer 110 while also ensuring the energy density of the battery fabricated from the electrode sheet 100.

[0101] In another possible implementation, in the second direction, the maximum distance between the edge of the opening of the first active layer 110 where the accommodation portion 150 is provided and the first tab slot 111 is in a range of 1 mm to 10 mm. This maximum distance is the distance between the farthest edge of the opening of the first tab slot 111, which is furthest from the first tab slot 111, and the first tab slot 111 in the second direction. It will be appreciated that this arrangement can ensure that the accommodation portion 150 improves lithium deposition in the first active layer 110 in the second direction while also ensuring the energy density of the battery fabricated from the electrode sheet 100.

[0102] Illustratively, the interval between two adjacent accommodating portions 150 on the first active layer 110 ranges from 100 μm to 2000 μm. For example, the interval between two adjacent accommodating portions 150 can be 200 μm, 500 μm, 1000 μm, 1500 μm, or 1800 μm.

[0103] Optionally, when a plurality of accommodation portions 150 are provided on the second active layer 120 , the interval between two adjacent accommodation portions 150 on the second active layer 120 is also in the range of 100 μm to 2000 μm.

[0104] When the spacing between two adjacent accommodating portions 150 is less than 100μm, the arrangement of the accommodating portions 150 is too dense, and the pole piece 100 loses a large amount of active material, resulting in a large capacity loss of the battery made of the pole piece 100. When the spacing between two adjacent accommodating portions 150 is greater than 2000μm, the arrangement of the accommodating portions 150 is too sparse, and the portion of the first active layer 110 between the two accommodating portions 150 still has a greater risk of lithium plating. In other words, setting the spacing between two adjacent accommodating portions 150 to 100μm-2000μm can reliably alleviate the occurrence of lithium plating in the first active layer 110 near the tab groove while ensuring the battery capacity.

[0105] At 25°C, a battery made with a conventional electrode sheet 100 and a battery made with a different electrode sheet 100 provided in this application were charged and discharged. Charging was performed at 3.5C / 4.0C / 4.5C to full charge voltage, with a cutoff of 0.05C. Discharging was performed at 1C to a cutoff voltage of 3.0V. This charge and discharge cycle was repeated 20 times, with the results shown in Table 1 below.

[0106] Table 1:

[0107] It can be seen from Table 1 that providing the accommodation portion 150 on the active material layer can effectively alleviate lithium plating in the area of ​​the active layer near the tab groove.

[0108] As shown in FIG4 and FIG5 , a first protective layer 160 is provided on a side of the first active layer 110 facing away from the current collector 130 , and the projection of the first protective layer 160 in the third direction covers the projection of the first tab groove 111 in the third direction.

[0109] Exemplarily, adhesive tape can be used as the first protective layer 160. When the first protective layer 160 is arranged on the first active layer 110, it completely covers the first pole tab groove 111. Exemplarily, the edge of the first protective layer 160 extends beyond the first pole tab groove 111, and the portion of the first protective layer 160 extending beyond the first pole tab groove 111 can be bonded and fixed to the first active layer 110.

[0110] Among them, the tab 140 can be electrically connected to the current collector 130 by welding. After the tab 140 is connected to the current collector 130, a first protective layer 160 is set on the first active layer 110. The first protective layer 160 can prevent the weld marks formed between the tab 140 and the current collector 130 from piercing the diaphragm and causing a short circuit in the battery.

[0111] In a possible implementation, as shown in FIG. 3 , in the first direction, a first gap H1 is defined between the first tab groove 111 and the adjacent accommodation portion 150 .

[0112] It can be understood that the end of the first protective layer 160 in the first direction exceeds the first tab groove 111, and the portion of the first protective layer 160 exceeding the first tab groove 111 can be bonded and fixed to the first gap to ensure the reliability of the connection between the first protective layer 160 and the first active layer 110.

[0113] In another possible implementation, as shown in FIG. 3 , in the second direction, a second gap H2 is defined between the first tab slot 111 and the accommodating portion 150 facing the first tab slot 111 .

[0114] It is understood that when the accommodating portion 150 is a groove, the end of the groove does not extend to the edge of the tab groove. The portion of the edge of the first protective layer 160 in the width direction of the pole piece 100 that extends beyond the first tab groove 111 can be bonded and fixed to the second gap to prevent the accommodating portion 150 from affecting the reliability of the connection between the first protective layer 160 and the first active layer 110.

[0115] Optionally, a first gap H1 is defined between the first tab slot 111 and the adjacent accommodation portion 150 in the first direction, and a second gap H2 is defined between the first tab slot 111 and the adjacent accommodation portion 150 in the second direction.

[0116] Specifically, when the pole piece has the first gap H1 , the first gap H1 ranges from 5 μm to 50 μm.

[0117] When the first gap is less than 5μm, the distance between the first tab groove 111 and the accommodating portion 150 is relatively close. When the first protective layer 160 is provided, the first protective layer 160 may cover the accommodating portion 150 in the length direction of the pole piece 100 due to assembly tolerance, thereby preventing the accommodating portion 150 from affecting the reliability of the connection between the first protective layer 160 and the first active layer 110. When the first gap is greater than 50μm, the distance between the first tab groove 111 and the accommodating portion 150 is relatively far. When the battery is charged at a high rate, the portion of the first active layer 110 located between the first tab groove 111 and the accommodating portion 150 may experience more lithium deposition. Setting the first gap to 5μm-50μm can ensure the reliability of the connection between the first protective layer 160 and the first active layer 110 while also preventing more lithium deposition on the first active layer 110.

[0118] When the pole piece has the second gap H2, the second gap H2 ranges from 5 μm to 50 μm.

[0119] With the above arrangement, the accommodation portion 150 can be prevented from affecting the reliability of the connection between the first protective layer 160 and the first active layer 110 , and more lithium deposition on the first active layer 110 can be prevented.

[0120] When the pole piece has both the first gap H1 and the second gap H2, the first gap H1 is in the range of 5 μm-50 μm, and the second gap H2 is in the range of 5 μm-50 μm.

[0121] As shown in FIG8 , the present application also provides a battery, comprising the above-mentioned electrode 100 .

[0122] For example, the electrode sheet 100 may be a negative electrode sheet, and the tab 140 on the electrode sheet 100 may be a negative tab. The battery provided in this embodiment further includes a positive electrode sheet 200 and a separator 300. The positive electrode sheet 200 is provided with a positive tab, and the separator 300 is provided between the positive electrode sheet 200 and the negative electrode sheet.

[0123] The battery cell can be either a rolled core or a stacked core. For example, after the positive electrode sheet 200, separator 300, and negative electrode sheet are stacked in sequence, they are wound along the length of the negative electrode sheet to form a rolled core. Schematically, both the positive and negative tabs are located near the center of the battery to reduce internal resistance and temperature rise. In one possible implementation, there can be multiple positive and negative tabs, with the number of positive and negative tabs being the same.

[0124] The battery can be prepared according to the following method, which includes:

[0125] Preparation of the positive electrode sheet 200: Lithium cobalt oxide, acetylene black, and polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 97:1.5:1.5, and N-methylpyrrolidone (NMP) was added and stirred to prepare a positive electrode active slurry with a solid content of 76%. This slurry was then evenly coated on both sides of 8μm aluminum foil using a conventional single-cavity extrusion coating die. The positive electrode sheet 200 was then dried, rolled, die-cut, slit, and cut into sheets.

[0126] Preparation of negative electrode sheet: Artificial graphite, acetylene black, styrene-butadiene rubber and sodium carboxymethyl cellulose are mixed in a mass ratio of 97:1:1:1, and deionized water is added to prepare a negative electrode active slurry with a solid content of 45%. Then, a conventional single-cavity extrusion coating die is used, followed by drying and rolling to form a thick electrode sheet 100 with a thickness of about 89 μm (the compaction density of the electrode sheet 100 is 1.70 g / cm3), and then cut into negative electrode sheets with a specification of 82 mm × 1441 mm.

[0127] After the electrode sheet 100 is cut, a laser can be used to form an accommodating portion 150 on the first active layer 110. For example, when the accommodating portion 150 is a groove, a laser can be used to create lines on the first active layer 110 near the first tab groove 111. By controlling the laser power and line spacing, the grooves can be evenly distributed on both sides of the negative electrode sheet. The structure of the electrode sheet 100 can be shown in Figures 3-5, and the structure of the accommodating portion 150 can be shown in Figure 6.

[0128] Preparation of electrolyte: In an environment with a water content of less than 10 ppm, non-aqueous organic solvents ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), propyl propionate (PP) and vinylene carbonate (VC) are mixed in a mass ratio of 20:30:20:28:2, and then lithium hexafluorophosphate (LiPF6) is added to dissolve and mix evenly to obtain an electrolyte, wherein the mass ratio of LiPF6 to the non-aqueous organic solvent is 9:91.

[0129] The positive electrode sheet 200 , the negative electrode sheet, and the separator 300 (polyethylene film) are stacked to form a battery cell, and the electrolyte is injected to produce a battery.

[0130] The battery provided in this embodiment adopts the above-mentioned electrode piece 100. Therefore, when the battery is charged at a high rate, lithium deposition is not likely to occur in the area of ​​the electrode piece 100 near the electrode tab groove, thereby ensuring the cycle performance of the battery.

[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A pole piece, characterized in that, It includes a current collector, a tab and a first active layer; The first active layer is coated on one side of the current collector, and a first electrode tab groove is provided on the first active layer; One end of the electrode tab extends into the first electrode tab slot and is electrically connected to the current collector; The first active layer located outside the first electrode tab groove is provided with a receiving portion, and an opening of the receiving portion on the first active layer is located on a side of the first active layer away from the current collector; The thickness of the first active layer at the location of the accommodation portion is smaller than the thickness of the first active layer in the area where the accommodation portion is not located; The ratio of the minimum thickness of the first active layer at the location of the accommodation portion to the thickness of the first active layer in a region where the accommodation portion is not located is in a range of 0.3-0.

7.

2. The pole piece according to claim 1, characterized in that, The pole piece further comprises a second active layer, the second active layer is coated on a side of the current collector away from the first active layer, the second active layer is also provided with the accommodation portion in a region corresponding to the first pole lug groove, and the opening of the accommodation portion on the second active layer is located on a side of the second active layer away from the current collector; The thickness of the second active layer at the location of the accommodation portion is smaller than the thickness of the second active layer in a region where the accommodation portion is not located.

3. The pole piece according to claim 2, characterized in that, The second active layer is provided with a second pole tab groove facing the first pole tab groove, and the accommodation portion on the second active layer is located outside the second pole tab groove.

4. The pole piece according to claim 2, wherein The projection of the second active layer in the third direction covers the first electrode tab groove, and the accommodation portion is provided in a region of the second active layer facing the first electrode tab groove.

5. The pole piece according to claim 1 or 2, characterized in that, The accommodation portion is a groove.

6. The pole piece according to claim 5, characterized in that, The width of the groove gradually decreases from the opening toward the current collector.

7. The electrode tab according to claim 5, wherein The groove extends along the second direction.

8. The pole piece according to claim 1, characterized in that, The total thickness of the first active layer is 50 μm-150 μm; and / or, The depth of the accommodation portion on the first active layer is 10 μm-50 μm; and / or, The width of the opening of the accommodation portion is 50 μm-200 μm.

9. The pole piece according to claim 1, characterized in that, There are multiple accommodating parts on the first active layer. The multiple accommodating parts are arranged on the first active layer at intervals, and the multiple accommodating parts are arranged around the first electrode tab groove.

10. The pole piece according to claim 9, characterized in that, In the first direction, the maximum distance between the edge of the opening of the first active layer where the accommodation portion is provided and the first electrode tab groove is in the range of 1 mm to 10 mm; and / or, In the second direction, a maximum distance between an edge of the opening of the first active layer where the accommodation portion is provided and the first electrode tab groove is in a range of 1 mm to 10 mm.

11. The electrode tab according to claim 9, wherein The interval between two adjacent accommodating portions on the first active layer ranges from 100 μm to 2000 μm.

12. The pole piece according to claim 9, wherein A first protective layer is disposed on a side of the first active layer facing away from the current collector, and a projection of the first protective layer in the third direction covers a projection of the first electrode tab groove in the third direction.

13. The pole piece according to claim 12, wherein In the first direction, a first gap exists between the first electrode tab groove and the adjacent accommodation portion; and / or, In the second direction, a second gap is provided between the first electrode tab groove and the accommodating portion directly facing the first electrode tab groove.

14. The pole piece according to claim 13, characterized in that, The range of the first gap is 5 μm - 50 μm; and / or, The range of the second gap is 5 μm - 50 μm.

15. The pole piece according to claim 3, characterized in that, A second protective layer is provided on the side of the second active layer facing away from the current collector, and the projection of the second protective layer in the third direction covers the projection of the second tab groove in the third direction.

16. A battery, characterized in that, It includes the electrode sheet according to any one of claims 1 - 15.

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