Pole piece, pole core, battery and electric device

Abstract

This application provides an electrode sheet, electrode core, battery, and electrical device, relating to the field of battery technology. The electrode sheet includes a current collector, a tab, and an active material layer. The active material layer is disposed on the surface of the current collector to form a coating area. A connection area is also provided on the surface of the current collector, and the tab is connected to the connection area. Multiple grooves are disposed on the surface of the active material layer away from the current collector, located on the side of the coating area closer to the connection area, and arranged along the length of the current collector. Along the length of the current collector, the depth of the grooves on the side away from the tab is less than the depth of the grooves on the side closer to the tab. The electrode sheet, electrode core, battery, and electrical device of this application are used to improve the lithium plating problem in batteries and enhance battery life and safety.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to an electrode sheet, an electrode core, a battery, and an electrical device. Background Technology

[0002] Rechargeable batteries (such as lithium-ion batteries) are widely used in consumer electronics. As the application of rechargeable batteries continues to expand, especially in electric bicycles and electric vehicles, there is a growing demand not only for increased battery energy density but also for excellent fast-charging performance.

[0003] Under fast charging conditions, the negative electrode area of ​​the battery forms a localized high current density region due to the current convergence effect, and its current density decreases in the direction away from the negative electrode. This non-uniform current distribution causes the potential near the negative electrode to be significantly lower than that of the electrode core. When the potential is lower than the lithium deposition critical value, lithium ions will preferentially be reduced to metallic lithium on the surface of the negative electrode (lithium plating) rather than embedded inside the negative electrode material.

[0004] Lithium plating can seriously affect the lifespan and safety of batteries. Utility Model Content

[0005] This application provides an electrode sheet, an electrode core, a battery, and an electrical device to improve the lithium plating problem of the battery and enhance its lifespan and safety.

[0006] In a first aspect, this application provides an electrode sheet, including a current collector, a tab, and an active material layer;

[0007] The active material layer is disposed on the surface of the current collector to form a coating area, and the surface of the current collector is also provided with a connection area, and the tab is connected to the connection area.

[0008] The surface of the active material layer away from the current collector is provided with multiple grooves, the grooves are located on the side of the coating area close to the connection area, and the multiple grooves are arranged along the length direction of the current collector.

[0009] Along the length of the current collector, the depth of the groove on the side away from the tab is less than the depth of the groove on the side closer to the tab.

[0010] As an optional implementation, in the length direction of the current collector, the volume of the groove on the side away from the electrode tab is smaller than the volume of the groove on the side closer to the electrode tab;

[0011] And / or, the inner surface area of ​​the groove on the side away from the electrode tab is smaller than the inner surface area of ​​the groove on the side closer to the electrode tab.

[0012] As an optional implementation, at least a portion of the grooves have a depth distribution that is arithmetically equal.

[0013] As an optional implementation, in the length direction of the current collector, in at least two adjacent grooves, the difference between the depth of the groove closer to the tab and the depth of the groove farther from the tab is greater than or equal to 0 and less than or equal to 10 μm.

[0014] As an optional implementation, at least a portion of the grooves have a depth that is proportionally distributed.

[0015] As an optional implementation, in the length direction of the current collector, in at least two adjacent grooves, the ratio of the depth of the groove farther from the electrode to the depth of the groove closer to the electrode is greater than or equal to 0.8 and less than or equal to 1.

[0016] As an alternative implementation, at least a portion of the tanks have a depth that is clustered.

[0017] As an optional implementation, several tanks arranged sequentially along the length of the current collector form a tank group;

[0018] In at least two adjacent groups of grooves, the difference between the depth of the groove in the group closer to the tab and the depth of the groove in the group farther from the tab is greater than or equal to 0 and less than or equal to 20 μm.

[0019] As an optional implementation, the number of tanks in the tank group is greater than or equal to 1 and less than or equal to 50.

[0020] As an optional implementation, the cross-sectional shape of the groove is at least one of a triangle, a quadrilateral, and a circular arc.

[0021] As an optional implementation, in the length direction of the current collector, the distance between the tank body away from the connection area and the edge of the coating area facing the connection area is greater than or equal to 10 mm and less than or equal to 150 mm.

[0022] As an optional implementation, the connection area is located at the end of the current collector along its length;

[0023] And / or, the connection area is located at the middle of the length direction of the current collector.

[0024] As an optional implementation, multiple grooves are arranged at equal intervals along the length of the current collector.

[0025] As an optional implementation, the depth of the tank is less than the thickness of the active material layer.

[0026] Secondly, this application provides an electrode core, including a positive electrode sheet, a separator, and a negative electrode sheet, wherein the separator is disposed between the positive electrode sheet and the negative electrode sheet, and at least one of the positive electrode sheet and the negative electrode sheet is any of the above-mentioned electrode sheets.

[0027] Thirdly, this application provides a battery, including a casing and any of the above-mentioned electrode cores, wherein the electrode cores are disposed inside the casing.

[0028] Fourthly, this application provides an electrical device comprising at least one of the aforementioned batteries.

[0029] The electrode sheet, electrode core, battery, and electrical device provided in this application include an electrode sheet comprising a current collector, a tab, and an active material layer; the active material layer is disposed on the surface of the current collector to form a coating area, and the surface of the current collector is also provided with a connection area, and the tab is connected to the connection area; multiple grooves are disposed on the surface of the active material layer away from the current collector, and the grooves are located on the side of the coating area close to the connection area, and the multiple grooves are arranged along the length direction of the current collector; in the length direction of the current collector, the depth of the groove on the side away from the tab is less than the depth of the groove on the side close to the tab.

[0030] By incorporating multiple grooves on the surface of the active material layer, the grooves increase the effective reaction area for the positive electrode, allowing for more uniform lithium ion extraction to match the lithium insertion rate of the negative electrode and reducing the risk of lithium plating. For the negative electrode, the grooves divide the high current density region on the surface of the active material layer into multiple reaction units, increasing the reaction area and reducing local current density, thereby effectively reducing lithium plating. Furthermore, by incorporating deeper grooves near the tab, a larger reaction area can be added in areas with higher current density, reducing excessively high local current density and thus reducing the risk of lithium plating. Simultaneously, by controlling the distribution of groove depth, capacity fluctuations and active material layer loss caused by the grooves can be avoided, preventing lithium plating caused by insufficient active material in the negative electrode. Attached Figure Description

[0031] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0032] Figure 1 Schematic diagram of the electrode structure provided in the embodiments of this application Figure 1 ;

[0033] Figure 2 Schematic diagram of the electrode structure provided in the embodiments of this application Figure 2 ;

[0034] Figure 3 Schematic diagram of the electrode structure provided in the embodiments of this application Figure 3 ;

[0035] Figure 4 for Figure 1 Looking up at the medium electrode film Figure 1 ;

[0036] Figure 5 for Figure 1 Looking up at the medium electrode film Figure 2 ;

[0037] Figure 6 for Figure 2 A bottom view of the intermediate electrode plate;

[0038] Figure 7 for Figure 3 A bottom view of the intermediate electrode plate.

[0039] Explanation of reference numerals in the attached figures:

[0040] 100. Current collector;

[0041] 101. Coating area;

[0042] 102. Connecting areas;

[0043] 200, Polar Ear;

[0044] 300. Active substance layer;

[0045] 301. Tank area;

[0046] 310. Tank assembly;

[0047] 311. Tank body.

[0048] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the embodiments of this application.

[0050] In the embodiments of this application, the terms "upper," "lower," "inner," "middle," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are mainly for better describing the embodiments of this application and their implementations, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation. Furthermore, some of the above terms may be used to indicate other meanings besides orientation or positional relationship; for example, the term "upper" may also be used in some cases to indicate a certain dependency or connection relationship. For those skilled in the art, the specific meaning of these terms in the embodiments of this application can be understood according to the specific circumstances.

[0051] Furthermore, the terms "set up," "connect," and "fix" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this disclosure according to the specific circumstances.

[0052] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the present application described herein can be implemented, for example, in orders other than those illustrated or described herein.

[0053] In this application, the terms "exemplarily" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplarily" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplarily" or "for example" is intended to present the relevant concepts in a specific manner.

[0054] As is known from the background technology, when a secondary battery (such as a lithium-ion battery) is being charged, lithium ions can be extracted from the positive electrode, pass through the electrolyte and the separator, and finally be inserted into the negative electrode material.

[0055] Fast charging requires a large number of lithium ions to be transferred in a short time, which exacerbates the "accumulation" of lithium ions on the negative electrode surface. Due to the current convergence effect, a local high current density area will form near the negative electrode tab, and the current density will decrease in the direction away from the negative electrode tab.

[0056] This non-uniform current distribution causes the potential near the negative electrode tab to be significantly lower than that of the electrode core. When the potential is lower than the lithium deposition critical value, lithium ions will preferentially be reduced to metallic lithium on the negative electrode surface (lithium plating) rather than embedded inside the negative electrode material.

[0057] Furthermore, during fast charging or high-rate charging, the positive electrode may release more lithium ions due to excessive current density. If the lithium intercalation capacity of the corresponding area of ​​the negative electrode (such as near the tab) is insufficient, these lithium ions may not be able to intercalate into the negative electrode and instead precipitate on the surface of the negative electrode, causing lithium plating and affecting the battery's lifespan and safety.

[0058] In view of this, embodiments of this application provide an electrode sheet, an electrode core, a battery, and an electrical device, wherein the electrode sheet includes a current collector, a tab, and an active material layer; the active material layer is disposed on the surface of the current collector to form a coating area, and the surface of the current collector is also provided with a connection area, and the tab is connected to the connection area; the surface of the active material layer away from the current collector is provided with a plurality of grooves, the grooves are located on the side of the coating area close to the connection area, and the plurality of grooves are arranged along the length direction of the current collector.

[0059] When the electrode is used as the positive electrode of the battery, by setting multiple grooves on the surface of the active material layer, more of the surface of the active material layer can be exposed, increasing the effective reaction area of ​​the positive electrode. This allows lithium ions to be extracted from the positive electrode more evenly and enter the electrolyte. It helps to match the lithium intercalation rate of the negative electrode under fast charging conditions, avoids excessively high lithium ion concentration on the surface of the negative electrode due to the release of potassium ions too quickly from the positive electrode, and reduces the risk of lithium plating.

[0060] When the electrode is used as the negative electrode of the battery, multiple grooves are set on the surface of the active material layer. These grooves divide the negative electrode surface into multiple reaction units. The volume of the active material in each unit is reduced, while the reaction area is increased due to the division of the grooves. This can reduce the local current density, especially in the high current density area near the negative electrode tab, and reduce the risk of lithium plating.

[0061] Along the length of the current collector, the depth of the groove on the side furthest from the tab is less than the depth on the side closer to the tab. By setting a deeper groove in the region near the tab, a larger reaction area can be increased in areas with higher current density, effectively dispersing the current density, reducing locally excessive current density, and minimizing the risk of lithium plating. Simultaneously, by controlling the depth distribution of the groove, capacity fluctuations and active material layer loss caused by the groove can be avoided, ensuring the areal density of the negative electrode, maintaining the ratio of the negative electrode active material layer capacity to the positive electrode active material layer capacity (N / P ratio), and preventing lithium plating due to insufficient negative electrode active material.

[0062] The technical solution of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0063] Combination Figure 1 As shown, the first aspect of this application provides an electrode sheet, including a current collector 100, a tab 200, and an active material layer 300; the active material layer 300 is disposed on the surface of the current collector 100 to form a coating area 101, and a connection area 102 is also disposed on the surface of the current collector 100, with the tab 200 connected to the connection area 102; a plurality of grooves 311 are disposed on the surface of the active material layer 300 away from the current collector 100, the grooves 311 being located on the side of the coating area 101 near the connection area 102, and the plurality of grooves 311 being arranged along the length direction X of the current collector 100.

[0064] Understandably, the basic structure of an electrode consists of a current collector 100, a tab 200, and an active material layer 300. The current collector 100 is typically made of metal foil (such as copper or aluminum) and provides a path for current conduction. The tab 200 is connected to a specific connection region 102, ensuring concentrated current conduction. The active material layer 300 is disposed in the coating region 101 and provides a site for lithium-ion insertion and extraction.

[0065] The tab 200 has a first end connected to the current collector 100, and the other end can extend to one side along the length X of the current collector 100. The tab 200 can connect the active material of the battery to an external circuit, ensuring that current can be effectively transferred from the battery to the electrical device, or from the charger to the battery.

[0066] The active material layer 300 is composed of materials capable of undergoing reversible electrochemical reactions. Taking lithium-ion batteries as an example, the positive electrode typically uses lithium metal oxides (such as LiCoO2, LiFePO4) as the active material layer 300, while the negative electrode typically uses graphite or other carbon-based materials as the active material layer 300.

[0067] During charging and discharging, lithium ions can move between the active material layers 300 of the positive and negative electrodes, while electrons flow in the external circuit, thereby realizing the storage and release of electrical energy.

[0068] Understandably, during fast charging or high-rate charging, the current density near the tab 200 is relatively high, and along the length X of the current collector 100, the current density gradually decreases the further away from the tab 200. Therefore, the current density near the tab 200 in the electrode exhibits a gradient distribution, with the gradient distribution direction being the same as the direction away from the tab 200, and showing a decreasing trend.

[0069] Multiple grooves 311 are provided on the surface of the active material layer 300. The grooves 311 are located on the side of the coating area 101 near the connection area 102, and the distribution direction of the multiple grooves 311 is consistent with the direction of the gradient distribution of the current density.

[0070] The tank 311 is located near the edge of the connection area 102, which can reduce the current transmission path and ensure that when the current is conducted from the tab 200 to the active material layer 300, it can quickly enter the location of the tank 311 and be evenly distributed.

[0071] When the electrode is used as the positive electrode of the battery, the tank 311 can expose more of the surface of the active material layer 300, increasing the effective reaction area of ​​the positive electrode. This allows lithium ions to be extracted from the positive electrode more evenly and enter the electrolyte, which helps to match the lithium intercalation rate of the negative electrode under fast charging conditions. It also avoids excessively high lithium ion concentration on the surface of the negative electrode due to the release of potassium ions too quickly from the positive electrode, thus reducing the risk of lithium plating.

[0072] When the electrode sheet is used as the negative electrode of the battery, multiple tanks 311 divide the negative electrode surface into multiple reaction units. The volume of the active material in each unit is reduced, while the reaction area is increased due to the division of the tanks 311. This can reduce the local current density, especially in the high current density area near the negative electrode tab, and reduce the risk of lithium plating.

[0073] Furthermore, in the length direction X of the current collector 100, the depth of the groove 311 on the side away from the tab 200 is less than the depth of the groove 311 on the side closer to the tab 200.

[0074] By setting a deeper trench 311 near the tab 200, a larger reaction area can be increased in areas with higher current density, effectively dispersing the current density, reducing locally excessive current density, and minimizing the risk of lithium plating. Simultaneously, by controlling the depth distribution of the trench 311, capacity fluctuations and active material layer 300 loss caused by the trench 311 can be avoided, ensuring the areal density of the negative electrode, maintaining the N / P ratio of the battery, and preventing lithium plating due to insufficient negative electrode active material.

[0075] It should be noted that the extension direction of the tank 311 can be parallel or approximately parallel to the width direction of the collector 100. When the extension direction of the tank 311 is parallel to the width direction of the collector 100, it facilitates the positioning and processing of the tank 311.

[0076] The end of the tank 311 in the extension direction can extend to the end of the current collector 100 in the entire width direction, or it can be located inside the current collector, as long as it can reduce the local excessive current density.

[0077] Specifically, the electrode provided in this application embodiment, by setting grooves 311 on the surface of the active material layer 300 and reasonably controlling the depth distribution of the grooves 311, can significantly reduce the risk of lithium plating under fast charging conditions, improve the safety and lifespan of the battery, and at the same time ensure the capacity stability and efficiency of the battery.

[0078] Combination Figures 4 to 7 As shown, in some embodiments, the volume of the groove 311 on the side away from the tab 200 in the length direction X of the current collector 100 is smaller than the volume of the groove 311 on the side closer to the tab 200.

[0079] By setting the tank 311 closer to the tab 200 to have a larger volume, the larger tank 311 volume can provide more reaction area in the region near the tab 200. For the positive electrode, a larger effective reaction area allows lithium ions to be extracted from the positive electrode uniformly to match the lithium insertion rate of the negative electrode, avoiding excessively high lithium ion concentration on the negative electrode surface due to excessively rapid release of potassium ions from the positive electrode, thus reducing the risk of lithium plating. For the negative electrode, the larger tank 311 volume also provides a larger reaction area, which can effectively disperse higher local current density and reduce the risk of lithium plating.

[0080] In some embodiments, in the longitudinal direction X of the current collector 100, the inner surface area of ​​the groove 311 on the side away from the tab 200 is smaller than the inner surface area of ​​the groove 311 on the side closer to the tab 200.

[0081] By configuring the tank 311, which is closer to the tab 200, to have a larger inner surface area, more reaction interfaces can be provided in the area near the tab 200, thereby providing more reaction interfaces in areas with higher current density. For the positive electrode, more reaction interfaces can promote uniform lithium-ion transport to match the lithium intercalation rate of the negative electrode, avoiding excessively high lithium-ion concentration on the negative electrode surface due to excessively rapid release of potassium ions from the positive electrode, thus reducing the risk of lithium plating. For the negative electrode, it can effectively disperse local current density, reducing the risk of lithium plating.

[0082] Combination Figure 4 As shown, in some embodiments, at least a portion of the grooves 311 have depths that are evenly distributed.

[0083] Along the length X of the current collector 100, the depth of the groove 311 is evenly distributed, which helps to smooth the gradient change of current density and avoid local current density peaks that may occur when the depth of the groove 311 changes too much. By maintaining a small difference in depth, the current density can be effectively dispersed in the region near the tab 200, reducing the risk of lithium plating.

[0084] Specifically, in the longitudinal direction X of the current collector 100, in at least two adjacent grooves 311, the groove 311 closer to the tab 200 has a depth H. n The depth H of the groove 311, which is far from the tab 200, is... n+1 The difference is greater than or equal to 0 and less than or equal to 10 μm.

[0085] By limiting the difference in depth between adjacent grooves 311, the depth of multiple grooves 311 can be ensured to vary gradually, which allows the current density to be distributed more evenly on the electrode surface.

[0086] Combination Figure 4 As shown, in some embodiments, at least a portion of the grooves 311 have a depth that is proportionally distributed.

[0087] Along the length direction X of the current collector 100, the depth of the groove 311 is evenly distributed, which helps to ensure a smooth transition of current density, reduce local current density peaks that may be caused by excessive depth changes, provide a more uniform current distribution in the area near the tab 200, optimize the lithium ion transport path, and reduce the risk of lithium plating.

[0088] Specifically, in the direction away from the tab 200, in at least two adjacent grooves 311, the depth H of the groove 311 away from the tab 200 is... n+1 The depth H of the groove 311 near the tab 200 n The ratio is greater than or equal to 0.8 and less than or equal to 1.

[0089] By limiting the ratio of the depth of the groove 311 far from the tab 200 to the depth of the groove 311 near the tab 200, it is helpful to ensure that the depth of the multiple grooves 311 varies gradually, so that the current density can be more evenly distributed on the surface of the electrode.

[0090] Combination Figure 1 and Figure 5 As shown in some embodiments, at least a portion of the tanks 311 have depths that are clustered together.

[0091] It should be noted that clustered distribution means that at least a portion of the tanks 311 can form a group, and the tanks 311 in each group have the same or similar depth, or there are other patterns (such as arithmetic or geometric progressions).

[0092] The multiple 311-group arrangement of the tanks can adapt to the current distribution requirements of different areas of the electrode, which helps to reduce local current density peaks.

[0093] Specifically, along the length direction X of the current collector 100, several sequentially arranged grooves 311 form a groove group 310; in at least two adjacent groove groups 310, the groove group 310 closest to the tab 200 (e.g. Figure 5 S in n The depth of the groove 311 in the middle is related to the depth of the groove assembly 310 (e.g., far from the tab 200) Figure 5 S in n+1 The difference in depth between the two grooves 311 is greater than or equal to 0 and less than or equal to 20 μm.

[0094] By controlling the difference in depth between groups, an arithmetic distribution of depth between groups can be achieved, resulting in a smooth transition in the depth of the inter-group trench 311. This optimizes the distribution of current density, avoids local current density concentration on the electrode, and thus reduces the risk of lithium plating.

[0095] In some embodiments, the number of tanks 311 in the tank group 310 is greater than or equal to 1 and less than or equal to 50.

[0096] By controlling the number of tanks 311 in the tank group 310, the reaction area and depth distribution of each tank group 311 can be flexibly controlled to ensure the optimized distribution of current density on the electrode and adapt to the current requirements of different regions.

[0097] It should be noted that the number of grooves 311 can be differentiated between the region near the tab 200 and the region far from the tab 200 to optimize the lithium-ion transport path and reaction efficiency. For example, fewer grooves 311 can be used in regions with relatively lower current density on the electrode, while more grooves 311 can be used in regions with relatively higher current density on the electrode.

[0098] In some embodiments, the cross-sectional shape of the groove 311 is at least one of a triangle, a quadrilateral, and an arc.

[0099] It should be noted that the cross-sectional shape of the tank 311 can be optimized according to specific current density requirements and manufacturing processes. By selecting a suitable cross-sectional shape, the distribution of current density and the lithium-ion transport path can be optimized, thereby reducing the risk of lithium plating and improving battery performance and safety.

[0100] For example, triangular cross-sections typically have smaller volume and surface area, making them suitable for areas on the electrode where current density is relatively low. Quadrilateral cross-sections can provide larger volume and surface area, making them suitable for areas on the electrode where current density is relatively high. Circular cross-sections can provide a smooth current transition and reduce sharp-corner effects, making them suitable for areas on the electrode where current density concentration needs to be reduced and current path optimized.

[0101] Combination Figure 1 and Figure 4 As shown, in some embodiments, in the length direction of the current collector 100, the distance L between the tank 311 away from the connection area 102 and the edge of the coating area 101 facing the connection area 102 is greater than or equal to 10 mm and less than or equal to 150 mm.

[0102] Understandably, multiple tanks 311 form a tank region 301 on the surface of the active material layer 300, and the tank region 301 is arranged adjacent to the connecting region 102; in the length direction X of the current collector 100, the tank region 301 is away from the edge of the connecting region 102, and the distance between the tank region 301 and the edge of the tank region 301 facing the connecting region 102 is greater than or equal to 10 mm and less than or equal to 150 mm.

[0103] By setting the tank area 301 adjacent to the connection area 102, with the tank area 301 close to the edge of the connection area 102, the current transmission path can be reduced, ensuring that when the current is conducted from the tab 200 to the active material layer 300, it can quickly enter the tank area 301 and be evenly distributed.

[0104] By controlling the distance L between the tank 311, which is far from the connection area 102, and the edge of the coating area 101 facing the connection area 102, the length of the tank area 301 is effectively controlled.

[0105] Understandably, an excessively long tank region 301 may lead to capacity fluctuations and loss of the active material layer 300, while an excessively short tank region 301 may not be sufficient to effectively distribute the current density.

[0106] By setting the distance L between the tank 311, which is far from the connection region 102, and the edge of the coating region 101 facing the connection region 102 to be greater than or equal to 10 mm and less than or equal to 150 mm, a balance can be achieved between increasing the surface area of ​​the active material layer 300 and maintaining an effective active material capacity. This ensures that the current is evenly distributed in the active material layer 300, reduces the risk of excessive local current density, and thus reduces the possibility of lithium plating.

[0107] Combination Figure 1 , Figure 4 and Figure 5 As shown, in some embodiments, the connection region 102 is located at the end of the current collector 100 near the +X direction.

[0108] Since the connection area 102 is connected to the tab 200, current can enter from the end of the electrode near the +X direction and be conducted along the -X direction. The tank area 301 is located on the side of the connection area 102 near the -X direction and is adjacent to the connection area 102. When the current density near the connection area 102 is high, the current will pass through the tank area 301 when conducted along the -X direction, which helps to achieve a uniform distribution of current density and improve the overall efficiency and performance of the battery.

[0109] Combination Figure 2 and Figure 6 As shown, in some embodiments, the connection region 102 is located at the end of the current collector 100 near the -X direction.

[0110] Since the connection region 102 is connected to the tab 200, current can enter from the end of the electrode near the -X direction and be conducted along the +X direction. The tank region 301 is located on the side of the connection region 102 near the +X direction and is adjacent to the connection region 102. When the current density near the connection region 102 is high, the current will pass through the tank region 301 when conducted along the +X direction, which helps to achieve a uniform distribution of current density and improve the overall efficiency and performance of the battery.

[0111] Combination Figure 3 and Figure 7 As shown, in some embodiments, the connection region 102 is located in the middle of the length direction X of the current collector 100.

[0112] Specifically, the tank region 301 is disposed adjacent to the connecting region 102, and the tank region 301 is located on the side of the connecting region 102 perpendicular to the length direction X of the collector 100. The first part of the tank region 301 extends along the -X direction, the second part extends along the +X direction, and the junction of the first part and the second part is located at the middle of the length direction X of the collector 100 in the connecting region 102.

[0113] Since the connection area 102 is connected to the tab 200, current can be conducted from the middle of the electrode simultaneously along the -X and +X directions.

[0114] When the current density near the connection area 102 is high, the current will pass through the first part of the tank area 301 when it is conducted along the -X direction, thus achieving a uniform distribution of current density; when the current is conducted along the +X direction, it will pass through the second part of the tank area 301, thus achieving a uniform distribution of current density.

[0115] Combination Figures 4 to 7 As shown, in some embodiments, multiple grooves 311 are arranged at equal intervals along the length direction X of the current collector 100.

[0116] It should be noted that if the tank 311 is arranged too densely, the current density may be concentrated in certain areas, causing local overheating and uneven electrochemical reaction, increasing the risk of lithium plating. Furthermore, an overly dense tank 311 may also cause capacity fluctuations and loss of the active material layer 300. If the tank 311 is arranged too sparsely, it may not be sufficient to effectively disperse the current density.

[0117] Specifically, the spacing between the tanks 311 can be flexibly designed according to actual application requirements, and this application embodiment does not impose any restrictions on this.

[0118] In some embodiments, the depth of the tank 311 is less than the thickness of the active material layer 300.

[0119] By setting the depth of the tank 311 to be less than the thickness of the active material layer 300, each position on the electrode in the length direction X of the current collector 100 has an effective reaction area to achieve lithium ion insertion and extraction; and it can also prevent the current collector 100 from being directly exposed to the electrolyte, reducing the risk of corrosion or other side reactions of the current collector 100.

[0120] Electrodes can be prepared according to the schemes of Examples 1, 2 and 3, as well as comparative examples, to process lithium-ion batteries and test the lithium-ion batteries.

[0121] The specific processing steps of the lithium-ion battery in each embodiment and comparative example are as follows: positive and negative electrode material preparation, positive and negative electrode slurry pulling, positive and negative electrode rolling, positive and negative electrode sheet making, winding, encapsulation, liquid injection, formation, aging, and sorting.

[0122] Specifically, in the negative electrode formulation, the mass percentages of graphite, binder, carboxymethyl cellulose, and conductive agent are as follows:

[0123] Graphite: binder: carboxymethyl cellulose: conductive agent = 96.5%: 1.5%: 1.5%: 0.5%, of which the solid content is 40%-55% and the slurry viscosity is 3000-6000 mPa.s.

[0124] The negative electrode paste uses 5μm copper foil, and the surface density of the negative electrode paste is 8.5mg / cm³. 2 .

[0125] The compaction density of the negative electrode roller is 1.65 g / cm³. 3 .

[0126] Specifically, in the positive electrode formulation, the mass percentages of lithium cobalt oxide, binder, and conductive agent are as follows:

[0127] Binder: Conductive agent = 98%: 1%: 1%, of which the solid content is 70% to 80% and the slurry viscosity is 3000 to 6000 mPa.s.

[0128] The positive electrode paste uses 10μm aluminum foil, and the positive electrode paste surface density is 13mg / cm³. 2 .

[0129] The compaction density of the positive electrode roller is 4.1 g / cm³. 3 .

[0130] Specifically, in Example 1, after the rolling process is completed, a plurality of grooves 311 are formed on the surface of the negative electrode sheet where the tabs 200 are located by laser etching. In the direction away from the tabs 200, in at least two adjacent grooves 311, the depth H of the groove 311 away from the tabs 200 is... n+1 The depth H of the groove 311 near the tab 200 n The ratio is 0.98; the distance L between the tank area 301 and the edge of the connecting area 102 is 60mm.

[0131] Specifically, in Embodiment 2, after the rolling process is completed, a plurality of grooves 311 are formed on the surface of the negative electrode sheet where the tabs 200 are located by laser etching. In the direction away from the tabs 200, in at least two adjacent grooves 311, the depth H of the groove 311 closer to the tabs 200 is... n The depth H of the groove 311, which is far from the tab 200, is... n+1 The difference is 0.5μm; the distance L between the tank region 301 and the edge of the connecting region 102 is 30mm.

[0132] Specifically, in Example 3, after the rolling process is completed, multiple grooves 311 are formed on the surface of the negative electrode sheet where the tabs 200 are located by laser etching. In the direction away from the tabs 200, five grooves 311 arranged in sequence form a groove group 310. In two adjacent groove groups 310, the difference in depth between the grooves 311 in the groove group 310 closer to the tabs 200 and the grooves 311 in the groove group 310 farther from the tabs 200 is 2 μm. The groove region 301 is away from the edge of the connecting region 102, and the distance L between the groove region 301 and the edge of the groove region 301 facing the connecting region 102 is 60 mm.

[0133] Specifically, in each embodiment and comparative example, a copper wire with a diameter of 40 μm is selected as the reference electrode, and the electrodes are assembled in the order of positive electrode, separator, reference electrode, separator, and negative electrode, and the tabs of the reference electrode are led out from the top, sides or bottom of the lithium-ion battery.

[0134] The resistance between the negative electrode and the reference electrode and the capacity retention rate of the battery after 100 cycles were tested in each embodiment and comparative example. The test results are shown in Table 1 - Resistance and Cycle Capacity Retention Rate of Lithium-ion Batteries (hereinafter referred to as Table 1).

[0135] Table 1 - Resistance and Cycle Capacity Retention of Lithium-ion Batteries

[0136] Example sequence number Resistance (mΩ) Capacity retention rate after 100 cycles Example 1 18.8 100％ Example 2 19.8 100％ Example 3 18.5 100％ Comparative Example 30.2 95％

[0137] As can be seen from Table 1, for the batteries of Examples 1, 2 and 3, the resistance between the negative electrode and the reference electrode ranges from 18mΩ to 20mΩ; while in the comparative battery, the resistance between the negative electrode and the reference electrode is larger, at 30.2mΩ.

[0138] For the batteries of Examples 1, 2, and 3, the capacity retention rate after 100 cycles was 100%, and there was no lithium plating on the negative electrode surface; while for the batteries of the comparative example, the capacity retention rate after 100 cycles decreased to about 95%.

[0139] Therefore, the electrode provided in this application embodiment can effectively reduce lithium plating, reduce battery internal resistance, and maintain good capacity retention after 100 cycles.

[0140] A second aspect of this application provides an electrode core, including a positive electrode, a separator, and a negative electrode, wherein the separator is disposed between the positive electrode and the negative electrode, and at least one of the positive electrode and the negative electrode is the electrode provided in any of the above embodiments.

[0141] The electrode sheet has been described in detail in the above embodiments and will not be repeated here.

[0142] It should be noted that the electrode core is the core component of the battery. In the electrode core, the positive and negative electrode plates are responsible for the insertion and extraction of lithium ions, respectively, while the separator acts as an interphase between the positive and negative electrodes to prevent short circuits, while allowing lithium ions to pass through.

[0143] When the electrode in the above embodiment is used as a positive electrode, the groove 311 disposed on the surface of the active material layer 300 can expose more of the surface of the active material layer 300, increasing the effective reaction area of ​​the positive electrode, so that lithium ions can be extracted from the positive electrode more uniformly and enter the electrolyte. This helps to match the lithium intercalation rate of the negative electrode under fast charging conditions, avoids excessively high lithium ion concentration on the surface of the negative electrode due to the release of potassium ions too quickly by the positive electrode, and reduces the risk of lithium plating.

[0144] When the electrode in the above embodiment is used as a negative electrode, the groove 311 disposed on the surface of the active material layer 300 divides the negative electrode surface into multiple reaction units. The volume of the active material in each unit is reduced, while the reaction area is increased due to the division of the groove 311. This can reduce the local current density, especially in the high current density area near the negative electrode tab, and reduce the risk of lithium plating.

[0145] A third aspect of this application provides a battery, including a casing and an electrode core provided in any of the above embodiments.

[0146] The core has been described in detail in the above embodiments and will not be repeated here.

[0147] For example, the battery may include a lithium-ion battery and a sodium-ion battery.

[0148] A fourth aspect of this application provides an electrical device including at least one battery provided in any of the above embodiments.

[0149] The battery has been described in detail in the above embodiments and will not be repeated here.

[0150] For example, the electrical equipment could be an electric bicycle or an electric car.

[0151] Finally, it should be noted that those skilled in the art, upon considering the specification and practicing the application disclosed herein, will readily conceive of other embodiments of the present application. The embodiments of this application are intended to cover any variations, uses, or adaptations of the embodiments of this application that follow the general principles of the embodiments of this application and include common knowledge or customary technical means in the art not disclosed in the embodiments of this application. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of the embodiments of this application are indicated by the following claims.

[0152] It should be understood that the embodiments of this application are not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from their scope. The scope of the embodiments of this application is limited only by the appended claims.

Claims

1. A pole piece, characterized in that, It includes a current collector (100), a tab (200), and an active material layer (300); The active material layer (300) is disposed on the surface of the current collector (100) to form a coating area (101). The surface of the current collector (100) is also provided with a connection area (102), and the tab (200) is connected to the connection area (102). The surface of the active material layer (300) facing away from the current collector (100) is provided with a plurality of grooves (311). The grooves (311) are located on the side of the coating area (101) close to the connection area (102). The plurality of grooves (311) are arranged along the length direction of the current collector (100). In the length direction of the current collector (100), the depth of the groove (311) on the side away from the tab (200) is less than the depth of the groove (311) on the side closer to the tab (200).

2. The pole piece of claim 1, wherein In the longitudinal direction of the current collector (100), the volume of the groove (311) on the side away from the tab (200) is smaller than the volume of the groove (311) on the side closer to the tab (200); And / or, the inner surface area of ​​the groove (311) on the side away from the tab (200) is smaller than the inner surface area of ​​the groove (311) on the side closer to the tab (200).

3. The pole piece of claim 1, wherein At least a portion of the grooves (311) have depths that are evenly distributed.

4. The pole piece of claim 3, wherein In the length direction of the current collector (100), in at least two adjacent grooves (311), the difference between the depth of the groove (311) closer to the tab (200) and the depth of the groove (311) farther from the tab (200) is greater than or equal to 0 and less than or equal to 10 μm.

5. The pole piece of claim 1, wherein At least a portion of the grooves (311) have a depth that is proportionally distributed.

6. The pole piece of claim 5, wherein In the length direction of the current collector (100), in at least two adjacent grooves (311), the ratio of the depth of the groove (311) farther from the tab (200) to the depth of the groove (311) closer to the tab (200) is greater than or equal to 0.8 and less than or equal to 1.

7. The pole piece of claim 1, wherein At least a portion of the depths of the tanks (311) are distributed in clusters.

8. The pole piece of claim 7, wherein Along the length of the current collector (100), several sequentially arranged tanks (311) form a tank group (310); In at least two adjacent groups of the grooves (310), the difference between the depth of the groove (311) in the group of the grooves (310) closer to the tab (200) and the depth of the groove (311) in the group of the grooves (310) farther from the tab (200) is greater than or equal to 0 and less than or equal to 20 μm.

9. The pole piece of claim 8, wherein In the tank group (310), the number of tanks (311) is greater than or equal to 1 and less than or equal to 50.

10. The electrode sheet according to any one of claims 1-9, characterized in that, The cross-sectional shape of the groove (311) is at least one of a triangle, a quadrilateral, and a circular arc.

11. The pole piece of any of claims 1-9, wherein, In the length direction of the current collector (100), the distance between the tank (311) away from the connection area (102) and the edge of the coating area (101) facing the connection area (102) is greater than or equal to 10 mm and less than or equal to 150 mm.

12. The pole piece of any of claims 1-9, wherein, The connection area (102) is located at the end of the current collector (100) along its length; And / or, the connection area (102) is located at the middle of the length direction of the current collector (100).

13. The pole piece of any of claims 1-9, wherein, Along the length of the current collector (100), a plurality of the grooves (311) are arranged at equal intervals.

14. The pole piece of any of claims 1-9, wherein, The depth of the tank (311) is less than the thickness of the active material layer (300).

15. A core, characterized by It includes a positive electrode, a separator, and a negative electrode, wherein the separator is disposed between the positive electrode and the negative electrode, and at least one of the positive electrode and the negative electrode is the electrode as described in any one of claims 1-14.

16. A battery, characterized by It includes a housing and the electrode core as described in claim 15, wherein the electrode core is disposed inside the housing.

17. An electrical appliance, characterized in that, It includes at least one battery as described in claim 16.

Images