Battery pole piece, battery monomer, battery and electric device

Abstract

The invention discloses a battery pole piece, a battery monomer, a battery and a power utilization device, the battery pole piece comprises a current collector and an active material film layer arranged on at least one side of the current collector, and the active material film layer comprises a first area and a second area located on at least one side of the first area along a first direction; the active material film layer comprises a plurality of pores, the plurality of pores are provided with openings located in the surface of the active material film layer, the plurality of pores comprise a first pore and a second pore, the opening of the first pore is arranged in the first area, and the opening of the second pore is arranged in the second area; the porosity V1 of the first region is less than the porosity V2 of the second region. According to the battery pole piece provided by the embodiment of the invention, precipitation of active ions can be reduced, the cycle capacity of the battery is stabilized, and the service life of the battery is prolonged; the invention also aims to provide a battery monomer, a battery and an electric device which can realize the beneficial effects of the battery pole piece.

Description

Technical Field

[0001] This application belongs to the technical field of batteries, and specifically relates to a battery electrode sheet, a battery cell, a battery, and an electrical device. Background Art

[0002] In recent years, with the wide application of battery cells represented by lithium-ion batteries, the performance of battery cells has received increasing attention.

[0003] During the charging and discharging processes of the battery, there is a phenomenon of uneven concentration of active ions in the battery electrode sheet, which may lead to capacity loss, shortened cycle life, and thermal runaway, reducing the performance stability and reliability of the battery.

[0004] Therefore, how to further improve the performance stability and reliability of the battery is an urgent problem to be solved. Summary of the Invention

[0005] The purpose of this application is to provide a battery electrode sheet. During the charging and discharging processes of the battery, the battery electrode sheet provided by the embodiments of this application can reduce the precipitation of active ions, stabilize the cycle capacity of the battery, and improve the service life of the battery. This application also aims to provide a battery cell, a battery, and an electrical device that can achieve the beneficial effects of the battery electrode sheet.

[0006] In a first aspect, an embodiment of this application provides a battery electrode sheet, including: a current collector and an active material film layer disposed on at least one side of the current collector. The active material film layer includes a first region and a second region located on at least one side of the first region along a first direction; the active material film layer contains a plurality of pores, the plurality of pores have openings on the surface of the active material film layer, and the plurality of pores include first pores and second pores:

[0007] The opening of the first pore is disposed in the first region,

[0008] The opening of the second pore is disposed in the second region, where

[0009] Based on the same volume of the active material film layer, the porosity V1 of the first region is less than the porosity V2 of the second region.

[0010] The technical solution of the embodiment of the present application introduces pores with different spatial capacities into different regions of the battery electrode sheet. Before the first charge and discharge, the electrolyte storage capacity of the first pores in the first region of the electrode sheet in the first direction is less, and the electrolyte storage capacity of the second pores in the second region of the battery electrode sheet in the first direction is more, and is more than the electrolyte storage capacity of the first pores in the first region. When the battery electrode sheet undergoes the first charge and discharge in the battery cell, the electrolyte contacts the electrode material (electrolyte / electrode interface) and reacts to form a passivation film. The formed passivation film only allows Li ions to pass through, but does not allow solvent molecules to pass through, thereby avoiding direct contact between the electrode material and the electrolyte. During the charge and discharge process of the battery, by controlling the different pore space capacities, the imbalance in the concentration of active ions in the pore electrolytes of the first pores and the second pores is improved, thereby increasing the utilization rate of the active material and facilitating the exertion of the battery capacity. For example, during the charge and discharge of the battery, the concentration of active ions in the first region is low, and the concentration of active ions in the second region is high, thereby reducing the lithium deposition caused by the inability to quickly complete lithium intercalation, and can also reduce the lithium deposition of the lithium-ion battery caused by abnormal lithium intercalation paths, improving the battery cycle capacity and battery life.

[0011] Secondly, due to the different concentrations of active ions, the battery electrode sheet also affects the fast charging performance of the battery to a certain extent. The battery electrode sheet of the present application improves the uneven concentration of active ions (such as lithium ions) in the battery electrode sheet, thereby improving the fast charging performance of the battery.

[0012] In any embodiment of the present application, the battery electrode sheet includes a negative electrode sheet, and the active material film layer includes a negative electrode active material film layer.

[0013] According to the embodiment of the present application, the porosity V1 of the first region in the negative electrode active material film layer of the negative electrode sheet is less than the porosity V2 of the second region, which can improve the difference in the concentration of active ions in the pore electrolytes of the first pores and the second pores, reduce the lithium deposition caused by the inability to quickly complete lithium intercalation, and can also reduce the lithium deposition of the lithium-ion battery caused by abnormal lithium intercalation paths, improving the battery cycle capacity and battery life.

[0014] Secondly, due to the different concentrations of active ions, the battery electrode sheet also affects the fast charging performance of the battery to a certain extent. The battery electrode sheet of the present application improves the uneven concentration of active ions in the battery electrode sheet, thereby improving the fast charging performance of the battery.

[0015] Furthermore, the negative electrode active material film layer may include silicon-based materials such as elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy materials. Such silicon-based materials have a relatively large volume change rate during the charge and discharge process of the battery, and the regions where the volume change of the silicon-based materials occurs are different and the degree is uneven. Therefore, the difference in the concentration of active ions in the pore electrolyte in the first pore and the second pore is further amplified. By controlling the porosity V1 of the first region to be less than the porosity V2 of the second region in the embodiment of the present application, the uneven concentration of active ions can be improved, and the cycle capacity, battery life, and fast charging performance of the battery can be enhanced.

[0016] In any embodiment of the present application, the first direction is the direction from the first region to the battery tab.

[0017] In any embodiment of the present application, the first direction is a direction intersecting the direction from the first region to the battery tab.

[0018] In any embodiment of the present application, the ratio of the projected area of the first region on the current collector to the projected area of the active material film layer on the current collector is 3% to 20%.

[0019] In any embodiment of the present application, the ratio of the projected area of the second region on the current collector to the projected area of the active material film layer on the current collector is 15% to 50%.

[0020] According to the embodiments of the present application, when the ratios of the projected areas of the first region and the second region on the current collector to the projected area of the active material film layer on the current collector are within the above ranges, it is beneficial to improve the uneven concentration of active ions in the first region and the second region, and enhance the cycle capacity, battery life, and fast charging performance of the battery.

[0021] When the ratios of the projected areas of the first region and the second region on the current collector to the projected area of the active material film layer on the current collector are within the above ranges, it is convenient to distinguish and sample them for detection subsequently.

[0022] In any embodiment of the present application, the cross-sectional areas of the pores in the first pore and the second pore are the same.

[0023] According to the embodiments of the present application, the cross-sectional areas of the pores in the first pore and the second pore are the same, which is conducive to the full utilization of the active material in the active film layer. The cross-sections of the pores with different areas may cause the active material in some areas not to participate in the electrochemical reaction, thus wasting some active material in the battery. The same cross-sectional area of the pores helps the ions in the electrolyte to quickly transport to the active material of the battery electrode. It helps to provide a uniform and stable ion transport path and reduce the impact on the charge and discharge performance and efficiency of the battery. The same cross-sectional area of the pores reduces the instability of the electrode material, such as local overcharge or over-discharge, thereby reducing the probability of shortening the battery life or causing safety problems.

[0024] In any embodiment of the present application, the depth d1 of the pores of more than 80% of the first pores located in the first region extending along the thickness direction of the active material film layer is less than the depth d2 of the pores of more than 80% of the second pores located in the second region extending along the thickness direction of the active material film layer.

[0025] According to the embodiments of the present application, during the charge and discharge process of the battery, by controlling the different pore space capacities, the imbalance of the concentration of active ions in the electrolyte in the pores of the first pore and the second pore is improved. For example, during the charge and discharge of the battery, the concentration of active ions in the first region is low, and the concentration of active ions in the second region is high, thereby reducing the lithium precipitation caused by the inability to quickly complete lithium intercalation, and also reducing the lithium precipitation of the lithium-ion battery caused by abnormal lithium intercalation paths, and improving the battery cycle capacity and battery life.

[0026] Secondly, due to the different concentrations of active ions, the battery electrode also affects the fast charging performance of the battery to a certain extent. The battery electrode of the present application improves the uneven concentration of active ions (such as lithium ions) in the battery electrode and improves the fast charging performance of the battery.

[0027] In any embodiment of the present application, along the thickness direction of the active material film layer, the depth d1 of the pores of the first pore extending along the thickness direction of the active material film layer is less than the depth d2 of the pores of the second pore extending along the thickness direction of the active material film layer.

[0028] According to the embodiments of the present application, within the range that can be clearly detected, for example, when the diameter of the pores is 1 μm to 100 μm, the depth d1 is less than the depth d2 for the pores of the first pore and the pores of the second pore, which is conducive to controlling the total volume of the first pore to be less than the total volume of the second pore, and is conducive to improving the imbalance of the concentration of active ions in the electrolyte in the pores of the first pore and the second pore. For example, during the charge and discharge of the battery, the concentration of active ions in the first region is low, and the concentration of active ions in the second region is high, thereby reducing the lithium precipitation caused by the inability to quickly complete lithium intercalation, and also reducing the lithium precipitation of the lithium-ion battery caused by abnormal lithium intercalation paths, and improving the battery cycle capacity and battery life.

[0029] In any embodiment of the present application, 0.01:1 ≤ d1 / D < 1:1, where the thickness of the active material film layer is represented by D; along the thickness direction of the active material film layer, the depth of the pore channels of the first pores along the thickness direction of the active material film layer is represented by d1.

[0030] According to the embodiments of the present application, controlling the ratio of d1 / D within the above range, the first pores with a certain pore channel depth exist in the active film layer with a thickness of D, which can increase the surface area of the first region where the first pores are located, allowing active ions to undergo more electrochemical reactions on the surface of this region, thereby increasing the utilization rate of the active material. It can provide more channels for ion diffusion in the first region where the first pores are located, making it easier for active ions to enter the active material film layer and promoting the charging and discharging processes of the battery.

[0031] In addition, the first pores with deeper pore channels in the first region of the active material film layer contribute to a more uniform distribution of the active material, ensuring that more active material can participate in the electrochemical reaction and improving its utilization rate. The first pores with deeper pore channels can provide more space to accommodate the expansion and contraction of the active material during the charging and discharging processes of the battery, helping to relieve stress and extend the battery life.

[0032] In any embodiment of the present application, 0.01:1 ≤ d2 / D < 1:1, where the thickness of the active material film layer is represented by D; the depth of the pore channels of the second pores along the thickness direction of the active material film layer is represented by d2.

[0033] According to the embodiments of the present application, controlling the ratio of d2 / D within the above range, the second pores with a certain pore channel depth exist in the active film layer with a thickness of D, which can increase the surface area of the second region where the second pores are located, allowing active ions to undergo more electrochemical reactions on the surface of the second region, thereby increasing the utilization rate of the active material. It can provide more channels for ion diffusion in the second region where the second pores are located, making it easier for active ions to enter the active material film layer and promoting the charging and discharging processes of the battery.

[0034] In addition, the second pores with deeper pore channels in the second region of the active material film layer contribute to a more uniform distribution of the active material, ensuring that more active material can participate in the electrochemical reaction and improving its utilization rate. The second pores with deeper pore channels can provide more space to accommodate the expansion and contraction of the active material during the charging and discharging processes of the battery, helping to relieve stress and extend the battery life.

[0035] In any embodiment of the present application, along the thickness direction of the active material film layer, the depth d1 of the pore channels of the first pores is 1 μm to 80 μm, and may be optionally 15 μm to 60 μm.

[0036] According to the embodiments of the present application, when the depth d1 of the pore channels of the first pores is within the above range, the first pores have a certain pore channel depth, which can increase the surface area of the active film layer of the electrode, allowing active ions to undergo more electrochemical reactions on these surfaces, thereby increasing the utilization rate of the active material. It can provide more channels for ion diffusion, making it easier for active ions to enter the active material film layer and promoting the charging and discharging processes of the battery.

[0037] In addition, the first pores with pore channels of appropriate depth contribute to a more uniform distribution of the active material, ensuring that more active material (active material) can participate in the electrochemical reaction and improving its utilization rate. The first pores with pore channels of appropriate depth can provide more space to accommodate the expansion and contraction of the active material during the charging and discharging processes of the battery, helping to relieve stress and extend the life of the battery.

[0038] In any embodiment of the present application, along the thickness direction of the active material film layer, the depth d2 of the pore channels of the second pores is 1 μm to 80 μm, and may be optionally 30 μm to 60 μm.

[0039] According to the embodiments of the present application, when the depth d2 of the pore channels of the second pores is within the above range, the second pores have a certain pore channel depth, which can increase the surface area of the active film layer of the electrode, thereby increasing the utilization rate of the active material. It can provide more channels for ion diffusion, making it easier for active ions to enter the active material film layer, allowing active ions to undergo more electrochemical reactions on these surfaces, and thus increasing the capacity of the battery. It can

[0040] Shorten the ion transport path and improve ion reaction kinetics.

[0041] In addition, the second pores with pore channels of appropriate depth contribute to a more uniform distribution of the active material, ensuring that more active material can participate in the electrochemical reaction and improving its utilization rate. The second pores with pore channels of appropriate depth can provide more space to accommodate the expansion and contraction of the active material during the charging and discharging processes of the battery, helping to relieve stress and extend the life of the battery.

[0042] In any embodiment of the present application, along the thickness direction of the active material film layer, the length difference between the depth d1 of the pore channels of the first pores and the depth d2 of the pore channels of the second pores is 0 to 50 μm, and may be optionally 5 μm to 40 μm.

[0043] According to the embodiments of the present application, within the range that can be clearly detected, for example, when the diameter of the pore channels is 1 μm to 100 μm, the length difference between the pore channels of the first pore and the pore channels of the second pore is 0 to 50 μm. When the length difference is 0, the total volume of the first pore can be controlled to be less than the total volume of the second pore by controlling the total length of the pore channels of the first pore in the active material film layer to be less than the total length of the pore channels of the second pore in the active material film layer or by controlling the cross-sectional area of the first pore to be less than the cross-sectional area of the second pore. The pore distribution density can also be controlled to achieve this. When the length difference is greater than 0 and less than or equal to 50 μm, it is beneficial to control the total volume of the first pore to be less than the total volume of the second pore, which is beneficial to improving the imbalance in the concentration of active ions in the pore electrolyte of the first pore and the second pore. For example, during the charge and discharge of the battery, the concentration of active ions in the first region is low, and the concentration of active ions in the second region is high, thereby reducing the lithium deposition caused by the inability to quickly complete lithium intercalation and also reducing the lithium deposition in the lithium-ion battery caused by abnormal lithium intercalation paths, improving the battery cycle capacity and battery life.

[0044] In any embodiment of the present application, the depth difference in the thickness direction of the active material film layer between the pore channels of any two adjacent pores in the first direction is 0 to 45 μm, and can be optionally 5 μm to 30 μm.

[0045] According to the embodiments of the present application, within the range that can be clearly detected, for example, when the diameter of the pore channels is 1 μm to 100 μm, the depth difference between the pore channels of two adjacent pores is 0 to 45 μm. When the depth difference is 0, the total volume of the first pore can be controlled to be less than the total volume of the second pore by controlling the total length of the pore channels of the first pore in the active material film layer to be less than the total length of the pore channels of the second pore in the active material film layer or by controlling the cross-sectional area of the first pore to be less than the cross-sectional area of the second pore.

[0046] When the depth difference is greater than 0 and less than or equal to 45 μm, the channels of any two adjacent pores in the first direction are distributed in a gradient. On the premise of controlling the total volume of the first pores to be less than the total volume of the second pores, it is beneficial to improve the uneven distribution of the concentration gradient of active ions in the pore electrolyte of the first pores and the second pores. For example, during the charge and discharge of the battery, the concentration of active ions in the first region is relatively low, and its concentration distribution shows a gradient within the first region alone (such as near the tab side or the bottom region of the anode plate of a lithium-ion battery), or the concentration of active ions in the second region is relatively high, and its concentration distribution shows a gradient within the second region alone (such as the central region of the lithium-ion battery electrode plate), and the concentration of active ions in the first region and the second region shows an uneven gradient distribution (such as the region near the tab side of the lithium-ion battery electrode plate and the central region). Therefore, the gradient distribution of the channels of any two adjacent pores in the first direction exactly solves this uneven distribution of the concentration gradient of active ions; thus, it reduces the lithium precipitation caused by the inability to quickly complete lithium intercalation, and can also reduce the lithium precipitation of lithium-ion batteries caused by abnormal lithium intercalation paths, improving the battery cycle capacity and battery life.

[0047] In addition, the gradient distribution of the pore depth can reduce the stress and changes in the battery during charge and discharge cycles, contributing to improving the battery cycle life.

[0048] In any embodiment of the present application, the distance between any two adjacent pores in the first direction is 0.1 mm to 300 mm.

[0049] According to the embodiments of the present application, when the distance between any two adjacent pores in the first direction is within the above range, it indicates that the pores are evenly distributed in the first direction, which is beneficial to controlling the total volume of the first pores to be less than the total volume of the second pores, improving the uneven distribution of the concentration gradient of active ions in the pore electrolyte of the first pores and the second pores, reducing the lithium precipitation of lithium-ion batteries caused by abnormal lithium intercalation paths, and improving the battery cycle capacity and battery life.

[0050] In any embodiment of the present application, the distance between any two adjacent pores in the second direction is 0.1 mm to 300 mm, and the second direction intersects the first direction.

[0051] According to the embodiments of the present application, when the distance between any two adjacent pores in the second direction is within the above range, it indicates that the pores are evenly distributed in the second direction, which is beneficial to controlling the total volume of the first pores to be less than the total volume of the second pores, improving the uneven distribution of the concentration gradient of active ions in the pore electrolyte of the first pores and the second pores, reducing the lithium precipitation of lithium-ion batteries caused by abnormal lithium intercalation paths, and improving the battery cycle capacity and battery life.

[0052] In any embodiment of the present application, the distribution density of pores at the openings of the active material film layer is 10 to 100 openings per square centimeter.

[0053] According to the embodiments of the present application, when the random distribution density of pores at the openings of the active material film layer is within the above range, more surface area and electrochemical reaction sites can be provided on the basis of considering the stability of the battery electrode sheet, thereby improving the battery cycle capacity and battery life.

[0054] In any embodiment of the present application, the ratio of the area of any one of the first pores or any one of the second pores on the surface of the active material film layer to the area of the active material film layer is (0.0006 to 0.05):1.

[0055] According to the embodiments of the present application, the ratio of the area of the first pores or any one of the second pores on the surface of the active material film layer to the area of the active material film layer affects the battery electrode sheet and battery performance. When the ratio of the area of the above-mentioned pores on the surface of the active material film layer to the area of the active material film layer is within the above range, a suitable electrochemical reaction surface can be provided, which can accelerate the transmission of electrons and ions, thereby improving the charging and discharging rates of the battery; it can make the battery electrode sheet exhibit appropriate expansion and contraction during the charge and discharge cycles of the battery, thereby possibly reducing the influence of this stress and enabling the battery to have a better life; it can improve the heat dissipation ability and may also increase the surface area of heat generation. Therefore, the above-mentioned suitable ratio can achieve the balance of the above-mentioned performances.

[0056] In any embodiment of the present application, the first pores and the second pores are circular in a cross-section parallel to the active material film layer, and the average diameter of the pores is 20 μm to 100 μm.

[0057] That the first pores and the second pores are circular in a cross-section parallel to the active material film layer can be understood as that the cross-section of the pore channels is circular. The cross-sectional areas of the pore channels of the first pores and the second pores can be the same or different.

[0058] In some alternative embodiments, the first pores and the second pores are square in a cross-section parallel to the active material film layer, and the average side length of the pores is 20 μm to 100 μm.

[0059] In some alternative embodiments, the first pores and the second pores are trapezoidal in a cross-section parallel to the active material film layer, and the average height of the trapezoid is 20 μm to 100 μm.

[0060] In some alternative embodiments, the first pores and the second pores are rectangular in a cross-section parallel to the active material film layer, and the average length of the longer side of the rectangle is 20 μm to 100 μm.

[0061] According to the embodiments of the present application, pores of different shapes and sizes such as circular, square, trapezoidal, and rectangular may result in different effective surface areas of the battery electrode sheet. A larger surface area helps more electrochemical reactions occur, improving the capacity and energy density of the battery. The shape of the pores also affects the permeability of the electrolyte. Larger and more open pore shapes may make it easier for the electrolyte to penetrate into the membrane layer, thereby accelerating the charge transfer and ion diffusion, and helping to improve the charging and discharging rates of the battery. The shape of the pores also affects the mechanical stability of the battery electrode sheet. For example, circular pores may increase the stability of the battery and improve its lifespan, while others may reduce the stability to some extent.

[0062] In some alternative embodiments, the tap density of the active material membrane layer is 1.3 m 2 / g to 1.9 m 2 / g.

[0063] According to the embodiments of the present application, when the tap density of the porosity of the active material membrane layer is within the above range, it means that more active materials can be included in the battery electrode sheet, thereby improving the capacity and energy density of the battery; it can improve the close contact degree of each component in the battery electrode sheet, such as the contact between the active material and the conductive agent, thereby improving the electron and ion transport speeds, and thus improving the charging and discharging rates of the battery; it can reduce the expansion and contraction of the battery electrode sheet during cycling, reduce the mechanical stress of the battery electrode sheet, and help improve the lifespan of the battery.

[0064] In some alternative embodiments, the porosity V1 of the first region is 20% - 35%.

[0065] In some alternative embodiments, the porosity V2 of the second region is 23% - 40%.

[0066] According to the embodiments of the present application, when the porosity of the first region and the porosity V2 of the second region are within the above ranges, the mechanical stability of the battery can be maintained, and the deformation and mechanical stress between the internal layers of the battery are reduced. This is beneficial to the lifespan and performance stability of the battery. The above porosities can provide sufficient active materials and allow the battery to achieve good capacity and energy density, can provide reasonable electron and ion transport paths, and help improve the charging and discharging rates of the battery. An appropriate porosity can reduce the expansion and contraction of the battery during cycling, reduce the mechanical stress of the battery, and help improve the cycle life of the battery.

[0067] In some alternative embodiments, the active material membrane layer includes a third region. Optionally, the porosity V3 of the third region is 19% - 34%.

[0068] According to the embodiments of the present application, the third region can be disposed between the first region and the second region, or can be disposed on a side of the first region away from the second region. The third region can be understood as the porosity of the solid part of the active material film layer of the present application. There are no pores similar to the first pore and the second pore in the third region. The active material film layer including the first region, the second region, and the third region can achieve the balance of the active ion concentration, which helps to improve the charging and discharging rates of the battery and helps to increase the cycle life of the battery.

[0069] In a second aspect, an embodiment of the present application provides a battery cell, including the battery electrode sheet of the first aspect.

[0070] In a third aspect, an embodiment of the present application provides a battery, including the battery cell of the second aspect.

[0071] In a fourth aspect, an embodiment of the present application provides an electrical device, including the battery of the third aspect.

[0072] The battery electrode sheet provided by the embodiments of the present application can reduce the precipitation of active ions, stabilize the cycle capacity of the battery, and increase the service life of the battery; the battery cell, the battery, and the electrical device including the battery electrode sheet at least have the above advantages. Description of the Drawings

[0073] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to the drawings without creative efforts.

[0074] Figure 1 It is a schematic diagram of an embodiment of the battery electrode sheet of the embodiment of the present application.

[0075] Figure 2 It is a schematic diagram of another embodiment of the battery electrode sheet of the embodiment of the present application.

[0076] Figure 3 It is a schematic diagram of still another embodiment of the battery electrode sheet of the embodiment of the present application.

[0077] Figure 4 It is a schematic diagram of an embodiment of the battery cell of the embodiment of the present application.

[0078] Figure 5 is Figure 1 the exploded schematic diagram of the battery cell shown.

[0079] Figure 6 It is a schematic diagram of an embodiment of an electrical device using the battery cell of the embodiment of the present application as a power source.

[0080] Among them, 10 is the battery electrode sheet, 110 is the second region, and 120 is the first region;

[0081] In the drawings, the drawings are not necessarily drawn to actual scale. Detailed implementation manners

[0082] Hereinafter, embodiments of the electrode assembly, its preparation method, battery cell, battery module, battery pack, and electrical device of the present application will be specifically described in detail with reference to the accompanying drawings as appropriate. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually identical structures are omitted. This is to prevent the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0083] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, ranges of 60-110 and 80-120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present application, unless otherwise stated, the numerical range "a-b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been fully listed herein, and "0-5" is only an abbreviated representation of these numerical combinations. In addition, when it is stated that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0084] If there is no special instruction, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution, and such a technical solution should be considered to be included in the disclosure of the present application.

[0085] If there is no special instruction, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution, and such a technical solution should be considered to be included in the disclosure of the present application.

[0086] Unless otherwise specified, all steps of this application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out sequentially, or may also include steps (b) and (a) carried out sequentially. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may also include steps (a), (c) and (b), or may also include steps (c), (a) and (b), etc.

[0087] Unless otherwise specified, the terms "comprising" and "including" mentioned in this application are open-ended and can also be closed-ended. For example, the terms "comprising" and "including" may mean that other components not listed may also be included or comprised, or may only include or comprise the listed components.

[0088] Unless otherwise specified, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0089] Unless otherwise specified, in this application, the terms "connected" and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0090] Unless otherwise specified, in this application, the term "attached" refers to being connected by means such as adhesion or coating.

[0091] Unless otherwise specified, in this application, the terms "first", "second", "third", "fourth", etc. are used to distinguish different objects, rather than to describe a specific order or primary-secondary relationship.

[0092] Unless otherwise specified, in this application, the term "active ion" refers to an ion that can intercalate and deintercalate between the positive and negative electrodes of a battery cell, including but not limited to lithium ions, sodium ions, etc.

[0093] The term "a plurality of" as used in this application means two or more (including two). The terms "a variety of" and "several" as used in this application mean two or more (including two).

[0094] In this application, the battery cell may include a lithium-ion battery, a sodium-ion battery, etc., and the embodiments of this application do not limit this. The battery cell may be an aqueous battery or an oil-based battery, and the embodiments of this application do not limit this either. The battery cell may be in the shape of a flat body, a cuboid, or other shapes, etc., and the embodiments of this application do not limit this either.

[0095] The battery cell, also known as a rechargeable battery or a storage battery, refers to a battery that can activate the active material through charging after discharging. Usually, the battery cell includes an electrode assembly and an electrolyte, and the electrode assembly includes electrode plates and a separator. The electrode plates include a positive electrode plate and a negative electrode plate.

[0096] Taking the negative electrode plate as an example, the negative electrode plate includes a negative current collector and a negative active material film layer provided on the negative current collector. Each component in the negative active material film layer is uniformly distributed therein, which is beneficial to the uniform infiltration of the electrolyte into the negative active material film layer, improving the concentration balance of active ions such as lithium ions, and is beneficial to ensuring the stability and performance of the battery.

[0097] Even so, due to the characteristics of the structure and materials of the battery itself, there is still an imbalance in the concentration of active ions in the battery electrolyte at different positions in the electrode plate, which may lead to capacity loss, shortened cycle life, thermal runaway, and reduce the performance stability and reliability of the battery, such as at the tab and the edge of the battery plate without a tab, the central area of the battery plate and the edge of the battery plate.

[0098] The imbalance in the concentration of active ions in the electrode plate can be caused by various reasons. These reasons may be that during the charging and discharging processes of the battery, the current density may be unevenly distributed on the surface of the electrode plate. This may cause the concentration of active ions on the surface of the electrode in some areas to increase, while the concentration of active ions on the surface of the electrode in other areas to decrease. It may also be caused by uneven electrode reaction rates, temperature gradients, and uneven electrolyte flow, etc., resulting in an imbalance in the concentration of active ions in the electrolyte in different areas of the electrode plate.

[0099] In view of this, this application provides an electrode plate that can arbitrarily control the concentration of active ions in different areas of the electrode plate, solving the problem of low performance and stability caused by the imbalance in the concentration of active ions in the electrolyte in the electrode plate.

[0100] Battery electrode plate

[0101] In a first aspect, an embodiment of this application provides a battery electrode plate, including: a current collector and an active material film layer provided on at least one side of the current collector, the active material film layer including a first region and a second region located on at least one side of the first region along a first direction; the active material film layer includes a plurality of pores, the plurality of pores have openings on the surface of the active material film layer, and the plurality of pores include first pores and second pores:

[0102] The opening of the first pore is disposed in the first region.

[0103] The opening of the second pore is disposed in the second region, where

[0104] Based on the active material film layer of the same volume, the porosity V1 of the first region is less than the porosity V2 of the second region.

[0105] According to the embodiments of the present application, the first region and the second region can be arbitrarily disposed in the active material film layer, which respectively represent the spatial regions between the surface of the active material film layer and the current collector. The first region and the second region can be disposed at intervals or can be adjacent to each other. The first region and the second region can belong to different non-overlapping regions in the active material film layer. The shapes of the first region and the second region on the surface of the active material film layer can be any shape, such as a rectangle or a circle. During the charge and discharge cycle of the battery, there may be a phenomenon of uneven active ion concentration in the electrolyte in the first region and the second region.

[0106] According to the embodiments of the present application, the pore can be understood as: a pore channel extending a certain depth in the thickness direction of the active material film layer from the surface of the active material film layer; the cross-sections of the opening and the pore channel have a predetermined shape. The pore channel of any one pore can form a certain angle with the thickness direction of the active material film layer. The angle can be 0 degree, that is, perpendicular to the active material film layer. The cross-sections of the opening and the pore channel of any one pore can be the same or different. The pore channels in the active material film layer can improve the wetting effect of the electrolyte, improve the concentration of active ions in this region, and the pore channels increase the surface area of the active material film layer, providing more sites where electrochemical reactions can occur.

[0107] The first direction can be a direction intersecting with the machine running direction (MD direction) of the battery electrode sheet, and can be optionally perpendicular to the machine running direction (MD direction) of the battery electrode sheet or can be the width direction (TD direction) of the battery electrode sheet. In some alternative embodiments, the first direction is the direction from the first region to the battery tab; in some alternative embodiments, the first direction is a direction intersecting with the direction from the first region to the battery tab.

[0108] In the embodiments of the present application, the battery electrode sheet can be a positive electrode sheet or a negative electrode sheet.

[0109] The technical solution of the embodiment of the present application introduces pores with different spatial capacities in different regions of the battery electrode sheet. Before the first charge and discharge, the electrolyte storage capacity of the first pores in the first region of the electrode sheet in the first direction is less, and the electrolyte storage capacity of the second pores in the second region of the battery electrode sheet in the first direction is more, and more than the electrolyte storage capacity of the first pores in the first region. When the battery electrode sheet undergoes the first charge and discharge in the battery cell, the electrolyte contacts the electrode material (electrolyte / electrode interface) and reacts to form a passivation film. The formed passivation film only allows Li ions to pass through, and does not allow solvent molecules to pass through, thereby avoiding direct contact between the electrode material and the electrolyte. During the charge and discharge process of the battery, by controlling the different pore space capacities, the uneven concentration of active ions in the pore electrolytes in the first pores and the second pores is improved. For example, during the charge and discharge of the battery, the concentration of active ions in the first region is low, and the concentration of active ions in the second region is high. By making the porosity V1 of the first region less than the porosity V2 of the second region, the concentration of active ions in the second region is reduced, thereby improving the uneven concentration of active ions in the first region and the second region, thereby reducing the lithium deposition caused by the inability to quickly complete lithium intercalation in the second region, and can also reduce the lithium deposition of the lithium-ion battery caused by abnormal lithium intercalation paths, improving battery reliability, cycle capacity, and battery life.

[0110] Secondly, due to the different concentrations of active ions in the battery electrode sheet, it also affects the fast charging performance of the battery to a certain extent. The battery electrode sheet of the present application improves the uneven concentration of active ions (such as lithium ions) in the battery electrode sheet, and improves the fast charging performance of the battery.

[0111] The porosity V1 of the first region being less than the porosity V2 of the second region, the specific method for detecting the pore volume ratio is as follows:

[0112] Porosity = pore volume per unit volume / volume of the active material film layer per unit volume of the electrode sheet

[0113] Specific detection method: Take an appropriate amount of sample, heat and vacuum degas for 2 h, wait until it cools to room temperature and then weigh the total weight, subtract the sample tube weight to obtain the sample weight. Then conduct the test: Install the sample tube into the BET adsorption and desorption instrument, and the amount of adsorbed gas can be obtained under constant low temperature conditions, thereby obtaining the porosity.

[0114] In some alternative embodiments, the ratio of the projected area of the first region on the current collector to the projected area of the active material film layer on the current collector is 3% - 20%. It can be optionally any value among 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20% or the range composed of them.

[0115] In some alternative embodiments, the ratio of the projected area of the second region on the current collector to the projected area of the active material film layer on the current collector is 15% to 50%. It can be optionally 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50% or any value within the range composed thereof.

[0116] According to the embodiments of the present application, when the ratios of the projected areas of the first region and the second region on the current collector to the projected area of the active material film layer on the current collector are within the above range, it is beneficial to improve the uneven concentration of active ions in the first region and the second region, and improve the cycle capacity, battery life and fast charging performance of the battery.

[0117] When the ratios of the projected areas of the first region and the second region on the current collector to the projected area of the active material film layer on the current collector are within the above range, it is convenient to distinguish and sample them for detection subsequently.

[0118] In some alternative embodiments, the cross-sectional areas of the pores in the first pore and the second pore are the same.

[0119] According to the embodiments of the present application, the same cross-sectional areas of the pores in the first pore and the second pore are beneficial to the full utilization of the active material of the active film layer. The cross-sectional areas of the pores with different areas may cause the active material in some regions not to participate in the electrochemical reaction, thus wasting some active materials in the battery. The same cross-sectional areas of the pores help the ions in the electrolyte to quickly transport to the active material of the battery electrode; help to provide a uniform and stable ion transport path, and reduce the impact on the charge and discharge performance and efficiency of the battery. The same cross-sectional areas of the pores reduce the uneven stress on the electrode material and improve the instability of the electrode material, such as local overcharge or over-discharge, thereby reducing the probability of shortening the battery life or causing safety problems.

[0120] The electrode material of the embodiments of the present application can be a positive electrode active material and a negative electrode active material.

[0121] The detection method for the cross-section of the pores in the first pore and the second pore can be a common method in the art, such as detecting with a scanning electron microscope. As an example, use ceramic scissors to cut the electrode sheet into a size of 6mm*6mm, stick it on the sample stage smeared with paraffin, and make the sample slightly protrude (<1mm) from the edge of the sample stage. b. Set the polishing voltage and time to polish the active material film layer in the electrode sheet. Observe the active material film layer of the polished electrode sheet with a scanning electron microscope to obtain the size of the pores at the cross-section position of the electrode sheet.

[0122] Those skilled in the art know that whether it is a wound-type battery cell or a stacked-type battery cell, it can be assembled with a battery having a length greater than the width. Among them, in the wound-type battery cell, first stack the positive electrode sheet, the separator, and the negative electrode sheet in sequence, then wind them, and set the tab; this makes the two edges of the battery electrode sheet in the width direction opposite to the side with the tab on the large-area electrode sheet and its opposite side edge. When the porosity V1 of the first region of the battery electrode sheet is less than the porosity V2 of the second region, it can help to promote the concentration balance of active ions. For example, it can reduce the concentration of active ions in the central region of the battery electrode sheet, thereby preventing the problem of lithium deposition in the center of the large-area electrode sheet caused by poor electrolyte infiltration during the cycling process.

[0123] In the stacked-type battery cell, include alternately placing the positive and negative single sheets on the Z-shaped folded separator and stacking them, and setting the tab; this makes the two edges of the battery electrode sheet in the width direction opposite to the side with the tab on the large-area electrode sheet and its opposite side edge. When the porosity V1 of the first region of the battery electrode sheet is less than the porosity V2 of the second region, it can help to promote the concentration balance of active ions. For example, it can reduce the concentration of active ions in the central region of the battery electrode sheet, thereby preventing the problem of lithium deposition in the center of the large-area electrode sheet caused by poor electrolyte infiltration during the cycling process.

[0124] There are also other types of battery cells in the art, such as battery cells assembled by stacking positive single sheets, separator single sheets, and negative single sheets in sequence and setting the tab. This makes the two edges of the battery electrode sheet in the width direction opposite to the side with the tab on the large-area electrode sheet and its opposite side edge. When the porosity V1 of the first region of the battery electrode sheet is less than the porosity V2 of the second region, it can help to promote the concentration balance of active ions. For example, it can reduce the concentration of active ions in the central region of the battery electrode sheet, thereby preventing the problem of lithium deposition in the center of the large-area electrode sheet caused by poor electrolyte infiltration during the cycling process.

[0125] In some alternative embodiments, the depth d1 of the pores of more than 80% of the first pores in the first region extending along the thickness direction of the active material film layer is less than the depth d2 of the pores of more than 80% of the second pores in the second region extending along the thickness direction of the active material film layer.

[0126] Optionally, the depth d1 of the pore channels of the first pores located within the first region at any value among 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100% or within the range formed by any combination thereof extending along the thickness direction of the active material film layer is less than the depth d2 of the pore channels of the second pores located within the second region at any value among 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100% or within the range thereof extending along the thickness direction of the active material film layer.

[0127] It can be understood that: the depth of the pore channels of the first pores within the first region does not necessarily have to be less than the depth of the pore channels of the second pores within the second region. There can be a small portion of the pore channels of the first pores within the first region whose depth does not necessarily have to be greater than the depth of the pore channels of the second pores within the second region. It is necessary to satisfy that the porosity V1 of the first region is less than the porosity V2 of the second region.

[0128] According to the embodiments of the present application, during the charge and discharge process of the battery, by controlling the different pore space capacities, the imbalance in the concentration of active ions in the electrolyte in the pore channels of the first pores and the second pores is improved. For example, during the charge and discharge of the battery, the concentration of active ions in the first region is relatively low, and the concentration of active ions in the second region is relatively high, thereby reducing the lithium deposition caused by the inability to quickly complete lithium intercalation, and it can also reduce the lithium deposition of the lithium-ion battery caused by abnormal lithium intercalation paths, improving the battery cycle capacity and battery life.

[0129] Secondly, due to the different concentrations of active ions, the battery electrode plate also affects the fast charging performance of the battery to a certain extent. The battery electrode plate of the present application improves the uneven concentration of active ions (such as lithium ions) in the battery electrode plate, thereby improving the fast charging performance of the battery.

[0130] The detection method for the depth of the pore channels of the first pores within the first region can be a common method in the art. For example, cut the electrode plate into a size of 6mm * 6mm with a ceramic scissors, stick it on a sample stage smeared with paraffin, and make the sample slightly protrude (<1mm) from the edge of the sample stage. b. Set the polishing voltage and time to polish the electrode plate. Observe the polished electrode plate with a scanning electron microscope, and the depth of the pore channels at the cross-sectional position of the active material film layer in the electrode plate can be obtained.

[0131] In some alternative embodiments, along the thickness direction of the active material film layer, the depth d1 of the pore channels of the first pores extending along the thickness direction of the active material film layer is less than the depth d2 of the pore channels of the second pores extending along the thickness direction of the active material film layer.

[0132] According to the embodiments of the present application, within the range that can be clearly detected, for example, when the diameter of the pore channels is 1 μm to 100 μm, the depth d1 of the pore channels of the first pores is less than the depth d2, which is beneficial to controlling the total volume of the first pores to be less than the total volume of the second pores, and is beneficial to improving the imbalance in the concentration of active ions in the pore electrolytes of the first pores and the second pores. For example, during the charge and discharge of the battery, the concentration of active ions in the first region is low, and the concentration of active ions in the second region is high, thereby reducing the lithium deposition caused by the inability to quickly complete lithium intercalation, and can also reduce the lithium deposition of the lithium-ion battery caused by abnormal lithium intercalation paths, improving the battery cycle capacity and battery life.

[0133] In some embodiments, the cross-sectional areas of the pore channels in the first pores and the second pores are the same. Along the thickness direction of the active material film layer, the depth d1 of the pore channels of the first pores extending along the thickness direction of the active material film layer is less than the depth d2 of the pore channels of the second pores extending along the thickness direction of the active material film layer. Therefore, it is possible to better control the total volume of the first pores to be less than the total volume of the second pores, which is beneficial to improving the imbalance in the concentration of active ions in the pore electrolytes of the first pores and the second pores.

[0134] In some alternative embodiments, 0.01:1 ≤ d1 / D < 1:1, where the thickness of the active material film layer is represented by D; along the thickness direction of the active material film layer, the depth of the pore channels of the first pores along the thickness direction of the active material film layer is represented by d1.

[0135] The ratio of d1 / D can be any value in 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, 0.11:1, 0.12:1, 0.13:1, 0.14:1, 0.15:1, 0.16:1, 0.17:1, 0.18:1, 0.19:1, 0.2:1, 0.21:1, 0.22:1, 0.23:1, 0.24:1, 0.25:1, 0.26:1, 0.27:1, 0.28:1, 0.29:1, 0.3:1, 0.31:1, 0.32:1, 0.33:1, 0.34:1, 0.35:1, 0.36:1, 0.37:1, 0.38:1, 0.39:1, 0.4:1, 0.41:1, 0.42:1, 0.43:1, 0.44:1, 0.45:1, 0.46:1, 0.47:1, 0.48:1, 0.49:1, 0.5:1, 0.51:1, 0.52:1, 0.53:1, 0.54:1, 0.55:1, 0.56:1, 0.57:1, 0.58:1, 0.59:1, 0.6:1, 0.61:1, 0.62:1, 0.63:1, 0.64:1, 0.65:1, 0.66:1, 0.67:1, 0.68:1, 0.69:1, 0.7:1, 0.71:1, 0.72:1, 0.73:1, 0.74:1, 0.75:1, 0.76:1, 0.77:1, 0.78:1, 0.79:1, 0.8:1, 0.81:1, 0.82:1, 0.83:1, 0.84:1, 0.85:1, 0.86:1, 0.87:1, 0.88:1, 0.89:1, 0.9:1, 0.91:1, 0.92:1, 0.93:1, 0.94:1, 0.95:1, 0.96:1, 0.97:1, 0.98:1, 0.99:1 or the range composed of them.

[0136] According to the embodiments of the present application, controlling the ratio of d1 / D within the above range, the first pores with a certain pore depth exist in the active membrane layer with a thickness of D, which can increase the surface area of the first region where the first pores are located, allowing active ions to undergo more electrochemical reactions on the surface of this region, thereby increasing the utilization rate of the active material. More channels for ion diffusion can be provided in the first region where the first pores are located, making it easier for active ions to enter the active material membrane layer and promoting the charging and discharging processes of the battery.

[0137] In addition, the first region of the active material film layer has first pores with deeper channels, which helps to more evenly distribute the active material, ensuring that more active material can participate in the electrochemical reaction and improving its utilization rate. The first pores with deeper channels can provide more space to accommodate the expansion and contraction of the active material during the charging and discharging processes of the battery, helping to relieve stress and extend the battery life.

[0138] In some alternative embodiments, 0.01:1 ≤ d2 / D < 1:1, where D represents the thickness of the active material film layer; and d2 represents the depth of the channels of the second pores in the direction of the thickness of the active material film layer.

[0139] The ratio of d2 / D can be any value in the range of 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, 0.11:1, 0.12:1, 0.13:1, 0.14:1, 0.15:1, 0.16:1, 0.17:1, 0.18:1, 0.19:1, 0.2:1, 0.21:1, 0.22:1, 0.23:1, 0.24:1, 0.25:1, 0.26:1, 0.27:1, 0.28:1, 0.29:1, 0.3:1, 0.31:1, 0.32:1, 0.33:1, 0.34:1, 0.35:1, 0.36:1, 0.37:1, 0.38:1, 0.39:1, 0.4:1, 0.41:1, 0.42:1, 0.43:1, 0.44:1, 0.45:1, 0.46:1, 0.47:1, 0.48:1, 0.49:1, 0.5:1, 0.51:1, 0.52:1, 0.53:1, 0.54:1, 0.55:1, 0.56:1, 0.57:1, 0.58:1, 0.59:1, 0.6:1, 0.61:1, 0.62:1, 0.63:1, 0.64:1, 0.65:1, 0.66:1, 0.67:1, 0.68:1, 0.69:1, 0.7:1, 0.71:1, 0.72:1, 0.73:1, 0.74:1, 0.75:1, 0.76:1, 0.77:1, 0.78:1, 0.79:1, 0.8:1, 0.81:1, 0.82:1, 0.83:1, 0.84:1, 0.85:1, 0.86:1, 0.87:1, 0.88:1, 0.89:1, 0.9:1, 0.91:1, 0.92:1, 0.93:1, 0.94:1, 0.95:1, 0.96:1, 0.97:1, 0.98:1, 0.99:1 or any range composed thereof.

[0140] According to the embodiments of the present application, controlling the ratio of d2 / D within the above range allows for the presence of second pores with a certain pore depth in the active membrane layer with a thickness of D. This can increase the surface area of the second region where the second pores are located, enabling more electrochemical reactions to occur on the surface of this region by active ions, thereby increasing the utilization rate of the active material. It can provide more channels for ion diffusion in the second region where the second pores are located, making it easier for active ions to enter the active material membrane layer and promoting the charging and discharging processes of the battery.

[0141] In addition, the second pores with deeper channels in the second region of the active material membrane layer contribute to a more uniform distribution of the active material, ensuring that more active material can participate in the electrochemical reaction and improving its utilization rate. The second pores with deeper channels can provide more space to accommodate the expansion and contraction of the active material during the charging and discharging processes of the battery, helping to relieve stress and extend the battery life.

[0142] In some alternative embodiments, the thickness of the active material membrane layer is 40 μm to 120 μm, and can be optionally 50 μm to 100 μm. In the embodiments of the present application, with the thickness of the active material membrane layer within the above range and by using the method of the present application to control the porosity of the first region and the second region, it is beneficial to balance the concentration of active ions in the active material membrane layer and beneficial to the battery performance.

[0143] In some alternative embodiments, along the thickness direction of the active material membrane layer, the depth d1 of the channels of the first pores is 1 μm to 80 μm, and can be optionally 15 μm to 60 μm.

[0144] Optionally, the depth d1 of the pore channels of the first pore can be any value between 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, 38 μm, 39 μm, 40 μm, 41 μm, 42 μm, 43 μm, 44 μm, 45 μm, 46 μm, 47 μm, 48 μm, 49 μm, 50 μm, 51 μm, 52 μm, 53 μm, 54 μm, 55 μm, 56 μm, 57 μm, 58 μm, 59 μm, 60 μm, 61 μm, 62 μm, 63 μm, 64 μm, 65 μm, 66 μm, 67 μm, 68 μm, 69 μm, 70 μm, 71 μm, 72 μm, 73 μm, 74 μm, 75 μm, 76 μm, 77 μm, 78 μm, 79 μm, 80 μm or a range composed of them.

[0145] According to the embodiments of the present application, when the depth d1 of the pore channels of the first pore is within the above range, the first pore has a certain pore channel depth, which can increase the surface area of the active film layer of the electrode plate, allow active ions to undergo more electrochemical reactions on these surfaces, improve the utilization rate of the active material, and promote the charging and discharging processes of the battery.

[0146] In addition, the first pore with pore channels of appropriate depth helps to more evenly distribute the active material, ensuring that more active material can participate in the electrochemical reaction and improving its utilization rate. The first pore with pore channels of appropriate depth can provide more space to accommodate the expansion and contraction of the active material during the charging and discharging processes of the battery, which helps to relieve stress and extend the life of the battery.

[0147] In some alternative embodiments, along the thickness direction of the active material film layer, the depth d2 of the pore channels of the second pore is 1 μm to 80 μm, and can be optionally 30 μm to 60 μm.

[0148] Optionally, the depth d2 of the pore channels of the first pores can be any value between 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, 38 μm, 39 μm, 40 μm, 41 μm, 42 μm, 43 μm, 44 μm, 45 μm, 46 μm, 47 μm, 48 μm, 49 μm, 50 μm, 51 μm, 52 μm, 53 μm, 54 μm, 55 μm, 56 μm, 57 μm, 58 μm, 59 μm, 60 μm, 61 μm, 62 μm, 63 μm, 64 μm, 65 μm, 66 μm, 67 μm, 68 μm, 69 μm, 70 μm, 71 μm, 72 μm, 73 μm, 74 μm, 75 μm, 76 μm, 77 μm, 78 μm, 79 μm, 80 μm or the range composed of them.

[0149] According to the embodiments of the present application, the depth d2 of the pore channels of the second pores is within the above range. The second pores have a certain pore channel depth, which can provide more channels for ion diffusion. Active ions can more easily enter the active material film layer, and the active ions can undergo more electrochemical reactions on these surfaces, thereby increasing the capacity of the battery. It can shorten the ion transport path and improve ion reaction kinetics.

[0150] In addition, the second pores with pore channels of appropriate depth help to more evenly distribute the active material, ensuring that more active material can participate in the electrochemical reaction and improving the utilization rate of the active material. The second pores with pore channels of appropriate depth can provide more space to accommodate the expansion and contraction of the active material during the charging and discharging process of the battery, which helps to relieve stress and extend the life of the battery.

[0151] In some alternative embodiments, along the thickness direction of the active material film layer, the length difference between the depth d1 of the pore channels of the first pores and the depth d2 of the pore channels of the second pores is 0 to 50 μm, and can be optionally 5 μm to 40 μm.

[0152] Optionally, the length difference between the depth d1 of the pore channels of the first pore and the depth d2 of the pore channels of the second pore can be any value between 0μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, 31μm, 32μm, 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, 44μm, 45μm, 46μm, 47μm, 48μm, 49μm, 50μm or the range composed of them.

[0153] According to the embodiments of the present application, within the range where the pore channels of the first pore and the pore channels of the second pore can be clearly detected, for example, when the diameter of the pore channels is 1μm - 100μm, the length difference is 0 - 50μm. When the length difference is 0, the total volume of the first pore can be controlled to be less than the total volume of the second pore by controlling the total length of the pore channels of the first pore in the active material film layer to be less than the total length of the pore channels of the second pore in the active material film layer or by controlling the cross-sectional area of the first pore to be less than the cross-sectional area of the second pore. The pore distribution density can also be controlled to achieve controlling the total volume of the first pore to be less than the total volume of the second pore; when the length difference is greater than 0 and less than or equal to 50μm, it is beneficial to control the total volume of the first pore to be less than the total volume of the second pore, which is beneficial to improving the imbalance of the concentration of active ions in the pore electrolyte of the first pore and the second pore. For example, during the charge and discharge of the battery, the concentration of active ions in the first region is relatively low, and the concentration of active ions in the second region is relatively high, thereby reducing the lithium precipitation caused by the inability to quickly complete lithium intercalation and also reducing the lithium precipitation of the lithium-ion battery caused by abnormal lithium intercalation paths, improving the battery cycle capacity and battery life.

[0154] In some embodiments, the cross-sectional areas of the pore channels in the first pore and the second pore are the same. Along the thickness direction of the active material film layer, the length difference between the depth d1 of the pore channels of the first pore and the depth d2 of the pore channels of the second pore is 0 - 50μm. By controlling the total length of the pore channels of the first pore in the active material film layer to be less than the total length of the pore channels of the second pore in the active material film layer, it is possible to better control the total volume of the first pore in the first region to be less than the total volume of the second pore in the second region and improve the imbalance of the concentration of active ions in the electrolyte in the first region and the second region.

[0155] In some alternative embodiments, the depth difference between the pore channels of any two adjacent pores in the first direction along the thickness direction of the active material film layer is 0 - 45μm, and can be optionally 5μm - 30μm.

[0156] Optionally, the depth difference between the channels of any two adjacent pores in the first direction along the thickness direction of the active material film layer can be any value among 0μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, 31μm, 32μm, 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, 44μm, 45μm or the range composed of them.

[0157] According to the embodiments of the present application, within the range where the channels of the first pore and the channels of the second pore can be clearly detected, for example, when the diameter of the channels is 1μm - 100μm, the depth difference between the channels of two adjacent pores is 0 - 45μm. When the depth difference is 0, by controlling the total length of the channels of the first pore in the active material film layer to be less than the total length of the channels of the second pore in the active material film layer or by controlling the cross-sectional area of the first pore to be less than the cross-sectional area of the second pore, the pore distribution density can also be controlled to achieve controlling the total volume of the first pore to be less than the total volume of the second pore.

[0158] When the depth difference is greater than 0 and less than or equal to 45μm, the channels of any two adjacent pores in the first direction are in a gradient distribution. On the premise of controlling the total volume of the first pore to be less than the total volume of the second pore, it is beneficial to improve the uneven distribution of the concentration gradient of active ions in the channel electrolyte in the first pore and the second pore. For example: during the charge and discharge of the battery, the concentration of active ions in the first region is relatively low, and its concentration distribution is gradually changing within the first region alone (for example, in a lithium-ion battery near the tab or the bottom of the electrode plate), or the concentration of active ions in the second region is relatively high, and its concentration distribution is gradually changing within the second region alone (for example, in the central region of the anode electrode plate of a lithium-ion battery), and the concentration of active ions in the first region and the second region is unevenly distributed in a gradient manner (for example, in the region near the tab and the central region of the anode of a lithium-ion battery). Therefore, the gradient distribution of the channels of any two adjacent pores in the first direction just solves this uneven distribution of the concentration gradient of active ions; thereby reducing the lithium precipitation caused by the inability to quickly complete lithium intercalation, and also reducing the lithium precipitation of the lithium-ion battery caused by abnormal lithium intercalation paths, and improving the cycle capacity and service life of the battery.

[0159] In addition, the gradient distribution of the pore depth distribution can reduce the stress and changes during the charge and discharge cycles of the battery, which helps to improve the cycle life of the battery.

[0160] In some alternative embodiments, the distance between any two adjacent pores in the first direction is 0.1 mm to 300 mm.

[0161] Optionally, the distance between any two adjacent pores in the first direction can be any value in the range consisting of 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 150 mm, 160 mm, 170 mm, 180 mm, 190 mm, 200 mm, 210 mm, 220 mm, 230 mm, 240 mm, 250 mm, 260 mm, 270 mm, 280 mm, 290 mm, 300 mm or any range composed thereof.

[0162] According to the embodiments of the present application, when the distance between any two adjacent pores in the first direction is within the above range, it indicates that the pores are evenly distributed in the first direction, which is beneficial to controlling the total volume of the first pores to be less than the total volume of the second pores, improving the uneven distribution of the concentration gradient of the active ions in the pore electrolyte in the first pores and the second pores, reducing the lithium precipitation of the lithium-ion battery caused by abnormal lithium insertion paths, and improving the battery cycle capacity and battery life.

[0163] In some alternative embodiments, the distance between any two adjacent pores in the second direction is 0.1 mm to 300 mm, and the second direction intersects the first direction.

[0164] The second direction can be a direction intersecting the first direction, or can be a direction perpendicular to the first direction, that is, the machine traveling direction (MD direction) when preparing the battery electrode sheet, or can be the length direction of the battery electrode sheet.

[0165] Optionally, the distance between any two adjacent pores in the second direction can be any value selected from 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 150 mm, 160 mm, 170 mm, 180 mm, 190 mm, 200 mm, 210 mm, 220 mm, 230 mm, 240 mm, 250 mm, 260 mm, 270 mm, 280 mm, 290 mm, 300 mm or the range composed of these values.

[0166] According to the embodiments of the present application, when the distance between any two adjacent pores in the second direction is within the above range, it indicates that the pores are evenly distributed in the second direction, which is beneficial to controlling the total volume of the first pores to be smaller than the total volume of the second pores, improving the uneven distribution of the concentration gradient of the active ions in the pore electrolyte in the first and second pores, reducing the lithium plating of the lithium-ion battery caused by abnormal lithium insertion paths, and increasing the battery cycle capacity and battery life.

[0167] In some alternative embodiments, the random distribution density of the openings of the pores in the active material film layer is 10 - 100 openings per square centimeter.

[0168] According to the embodiments of the present application, when the random distribution density of the openings of the pores in the active material film layer is within the above range, on the basis of considering the stability of the battery electrode sheet, more surface area and electrochemical reaction sites can be provided, increasing the battery cycle capacity and battery life.

[0169] In some embodiments, the openings of several pores are distributed on the surface of the active material film layer in an array manner. According to the embodiments of the present application, the openings of the pores being distributed on the surface of the active material film layer in an array manner is beneficial to improving the stability of the battery electrode sheet, can provide more surface area and electrochemical reaction sites, and increase the battery cycle capacity and battery life.

[0170] In some alternative embodiments, the ratio of the area of any one of the first pores or any one of the second pores on the surface of the active material film layer to the area of the active material film layer is (0.0006 - 0.05):1.

[0171] According to an embodiment of the present application, the ratio of the area of the first pore or any one of the second pores on the surface of the active material film layer to the area of the active material film layer affects the battery electrode sheet and battery performance. When the ratio of the area of the above pores on the surface of the active material film layer to the area of the active material film layer is within the above range, a suitable electrochemical reaction surface can be provided, which can accelerate the transmission of electrons and ions, thereby improving the charging and discharging rates of the battery; it can make the battery electrode sheet exhibit appropriate expansion and contraction during the charge and discharge cycles of the battery, thereby possibly reducing the influence of the stress and enabling the battery to have a better lifespan; it can improve the heat dissipation ability and may also increase the surface area for heat generation. Therefore, the above suitable ratio can achieve the balance of the above performances.

[0172] In some embodiments, the extending direction of the pore channels is parallel to the thickness direction of the active material film layer, the cross-sectional areas of the pore channels in the first pores and the second pores are the same, and the ratio of the cross-sectional area of the pore channel of any one of the first pores or any one of the second pores to the area of the active material film layer is (0.0006 - 0.05):1.

[0173] According to an embodiment of the present application, when the ratio of the cross-sectional area of the pore channels to the area of the active material film layer is within the above range, a suitable electrochemical reaction surface can be provided, which can accelerate the transmission of electrons and ions, thereby improving the charging and discharging rates of the battery; it can make the battery electrode sheet exhibit appropriate expansion and contraction during the charge and discharge cycles of the battery, thereby possibly reducing the influence of the stress and enabling the battery to have a better lifespan; it can improve the heat dissipation ability and may also increase the surface area for heat generation. Therefore, the above suitable ratio can achieve the balance of the above performances.

[0174] In some alternative embodiments, the first pores and the second pores are circular in the cross-section parallel to the active material film layer, and the average diameter of the pores is 20μm - 100μm.

[0175] That the first pores and the second pores are circular in the cross-section parallel to the active material film layer can be understood as that the cross-section of the pore channels is circular. The cross-sectional areas of the pore channels of the first pores and the second pores can be the same or different.

[0176] Optionally, the average diameter of the pores can be any value among 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm or the range composed of them.

[0177] In some alternative embodiments, the first pores and the second pores are square in the cross-section parallel to the active material film layer, and the average side length of the pores is 20μm - 100μm.

[0178] It can be understood that the cross-sections of the first pore and the second pore are circular in the cross-section parallel to the active material film layer, and the cross-section of the pore channel is square. The cross-sectional areas of the pore channels of the first pore and the second pore can be the same or different. Optionally, the average side length of the pore can be any value among 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm or the range composed thereof.

[0179] In some alternative embodiments, the first pore and the second pore are trapezoidal in the cross-section parallel to the active material film layer, and the average height of the trapezoid is 20μm to 100μm.

[0180] It can be understood that the cross-sections of the first pore and the second pore are circular in the cross-section parallel to the active material film layer, and the cross-section of the pore channel is trapezoidal. The cross-sectional areas of the pore channels of the first pore and the second pore can be the same or different. Optionally, the average height of the pore can be any value among 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm or the range composed thereof.

[0181] In some alternative embodiments, the first pore and the second pore are rectangular in the cross-section parallel to the active material film layer, and the average length of the longer side of the rectangle is 20μm to 100μm.

[0182] It can be understood that the cross-sections of the first pore and the second pore are circular in the cross-section parallel to the active material film layer, and the cross-section of the pore channel is rectangular. The cross-sectional areas of the pore channels of the first pore and the second pore can be the same or different. Optionally, the average length of the longer side of the rectangle can be any value among 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm or the range composed thereof.

[0183] According to the embodiments of the present application, pores of different shapes and sizes such as circular, square, trapezoidal, and rectangular may result in different effective surface areas of the battery electrode sheet. A larger surface area helps more electrochemical reactions occur, improving the capacity and energy density of the battery. The shape of the pores also affects the permeability of the electrolyte. Larger and more open pore shapes may make it easier for the electrolyte to penetrate into the membrane layer, thereby accelerating charge transfer and ion diffusion, and helping to improve the charging and discharging rates of the battery. The shape of the pores also affects the mechanical stability of the battery electrode sheet. For example, circular pores may increase the stability of the battery and improve its lifespan, while others may have a certain reduction in stability.

[0184] In some alternative embodiments, the areal density of the active material film layer is 1.5 m 2 / g to 1.8 m 2 / g.

[0185] The tap density of the active material film layer has the meaning well-known in the art and can be measured by instruments and methods well-known in the art. For example, for a negative electrode sheet that is single-sided coated and cold-pressed (if it is a double-sided coated negative electrode sheet, the negative electrode film on one side can be wiped off first), it is punched into small round pieces with an area of S 1 , and its weight is measured and recorded as M 1 . Then, the negative electrode film of the above-mentioned weighed negative electrode sheet is wiped off, and the weight of the negative electrode current collector is measured and recorded as M 0 . The areal density of the negative electrode film = (the weight M 1 of the negative electrode sheet - the weight M 0 of the negative electrode current collector) / S 1 .

[0186] In some alternative embodiments, the tap density of the active material film layer is 1.3 m 2 / g to 1.9 m 2 / g.

[0187] Optionally, the tap density of the active material film layer can be any value or a range composed thereof among 1.3 m 2 / g, 1.4 m 2 / g, 1.5 m 2 / g, 1.6 m 2 / g, 1.7 m 2 / g, 1.8 m 2 / g, 1.9 m 2 / g.

[0188] According to the embodiments of the present application, the tap density of the active material film layer within the above range means that more active material can be included in the battery electrode sheet, thereby improving the capacity and energy density of the battery; it can improve the close contact degree of each component in the battery electrode sheet, such as the contact between the active material and the conductive agent, thereby improving the electron and ion transport speed, and thus improving the charging and discharging rates of the battery; it can reduce the expansion and contraction of the battery electrode sheet during the cycling process, reduce the mechanical stress of the battery electrode sheet, and contribute to improving the battery life.

[0189] The tap density of the active material film layer has a well-known meaning in the art and can be measured by well-known instruments and methods in the art. For example, take the negative electrode sheet after single-sided coating and cold pressing, measure the thickness of the negative electrode film sheet, and then measure the areal density of the negative electrode film sheet according to the above method. The tap density of the negative electrode film sheet = the areal density of the negative electrode film sheet / the thickness of the negative electrode film sheet.

[0190] In some alternative embodiments, the porosity of the active material film layer is 20% - 35%.

[0191] In some alternative embodiments, the porosity V1 of the first region is 20% - 35%. Optionally, the porosity V1 of the first region can be any value among 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35% or a range composed thereof.

[0192] In some alternative embodiments, the porosity V2 of the second region is 23% - 40%. Optionally, the porosity V1 of the second region can be any value among 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40% or a range composed thereof.

[0193] According to the embodiments of the present application, the porosity V1 of the first region and the porosity V2 of the second region are within the above range

[0194] According to the embodiments of the present application, the porosity of the active material film layer within the above range can maintain the mechanical stability of the battery and reduce the deformation and mechanical stress between the internal layers of the battery. This is beneficial to the battery life and performance stability. The above porosity can provide sufficient active material and allow the battery to achieve good capacity and energy density, and can provide a reasonable electron and ion transport path, which helps to improve the charging and discharging rates of the battery. An appropriate porosity can reduce the expansion and contraction of the battery during the cycling process, reduce the mechanical stress of the battery, and contribute to improving the cycle life of the battery.

[0195] In some optional embodiments, the active material film layer includes a third region. Optionally, the porosity V3 of the third region is 19%-34%. Optionally, the porosity V3 of the third region can be any value or a range of its composition among 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%.

[0196] According to an embodiment of the present application, the third region can be arranged between the first region and the second region, and can also be arranged on the side of the first region away from the second region. The third region can be understood as the entity part of the active material film layer. The present application has a porosity. No pores similar to the first pore and the second pore are arranged in the third region. The active material film layer includes the first region, the second region and the third region to achieve a balance of active ion concentration, which helps to improve the charging and discharging rate of the battery and helps to increase the cycle life of the battery.

[0197] In some optional embodiments, (V1-V3)<(V2-V3). According to an embodiment of the present application, V1-V3 represents the pore volume of the first pores in the first region in the active material membrane layer / the volume of the active material membrane layer in the first region. V2-V3 represents the pore volume of the second pores in the second region in the active material membrane layer / the volume of the active material membrane layer in the second region. By setting (V1-V3)<(V2-V3), it is explained that the pore volume of the active first pores in the first region is smaller than the pore volume of the active second pores in the second region. And the change in pore volume occurs in the first region and the second region. There is also a third active material membrane layer, and the porosity of the solid part of itself has not changed.

[0198] The porosity detection method can be a commonly used method in the art. As an example, a sample of the active material film layer is inserted into a sample cup, and the sample cup containing the active material film layer is placed in a true density tester; a closed test system is used, and helium is introduced according to the program. The pressure of the gas in the sample chamber and the expansion chamber is detected, and the real volume is calculated according to Bohr's law (PV=nRT), thereby obtaining the porosity of the isolation film sample to be tested. Sample cup volume: 3.5cm 3 , analysis gas: helium.

[0199] See also Figures 1 - 3, which respectively show schematic diagrams of the surface structure of a battery electrode sheet 10. The battery electrode sheet 10 includes: a current collector and an active material film layer provided on at least one side of the current collector. The active material film layer includes a first region 120 and a second region 110 located on at least one side of the first region 110 along the first direction; the active material film layer contains a plurality of pores, and the plurality of pores have openings on the surface of the active material film layer. The plurality of pores include first pores and second pores:

[0200] The openings of the first pores are provided in the first region 120,

[0201] The openings of the second pores are provided in the second region 110, where

[0202] Based on the same volume of the active material film layer, the porosity V1 of the first region is less than the porosity V2 of the second region.

[0203] Figures 1 - 3 In the [negative electrode sheet], the length direction of the battery electrode sheet can be wound around the X direction.

[0204] [Negative electrode sheet]

[0205] In some alternative embodiments, the battery electrode sheet includes a negative electrode sheet, and the active material film layer includes a negative electrode active material film layer.

[0206] According to the embodiments of the present application, the porosity V1 of the first region in the negative electrode active material film layer of the negative electrode sheet is less than the porosity V2 of the second region, which can improve the difference in the concentration of active ions in the pore electrolyte in the first pores and the second pores, reduce the lithium deposition caused by the inability to quickly complete lithium intercalation, and can also reduce the lithium deposition of the lithium ion battery caused by abnormal lithium intercalation paths, and improve the battery cycle capacity and battery life.

[0207] Secondly, due to the different concentrations of active ions, the battery electrode sheet also affects the fast charging performance of the battery to a certain extent. The battery electrode sheet of the present application improves the battery electrode sheet due to uneven active ion concentration and improves the fast charging performance of the battery.

[0208] Furthermore, the negative electrode active material film layer may include silicon-based materials such as elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloy materials. Such silicon-based materials have a large volume change rate during the charge and discharge process of the battery, and the regions where the silicon-based materials undergo volume changes are different and the degrees are uneven. Therefore, the difference in the concentration of active ions in the pore electrolyte in the first pores and the second pores is further amplified. Controlling the porosity V1 of the first region to be less than the porosity V2 of the second region according to the embodiments of the present application can improve the unevenness of the active ion concentration, and improve the battery cycle capacity, battery life, and fast charging performance of the battery.

[0209] The specific composition and structure of the negative electrode plate can be selected according to the type of battery cell, and the embodiments of the present application do not limit this.

[0210] For example, when the battery cell is a lithium-ion battery cell or a sodium-ion battery cell, the negative electrode plate includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector and including a negative electrode active material. For example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode film layer is provided on any one or both of the two opposite surfaces of the negative electrode current collector.

[0211] The negative electrode active material is a material capable of deintercalating and intercalating active ions (such as lithium ions, sodium ions, etc.). The negative electrode active material can be a material well-known in the art. As an example, the negative electrode active material includes, but is not limited to, one or more of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based materials can include one or more of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloy materials. The tin-based materials can include one or more of elemental tin, tin oxides, and tin alloy materials. The present application is not limited to these materials, and other conventionally well-known materials that can be used as negative electrode active materials can also be used.

[0212] In some embodiments, the negative electrode film layer may optionally further include a negative electrode conductive agent. The present application does not particularly limit the type of the negative electrode conductive agent. As an example, the negative electrode conductive agent can include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0213] In some embodiments, the negative electrode film layer may optionally further include a negative electrode binder. The present application does not particularly limit the type of the negative electrode binder. As an example, the negative electrode binder can include one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resins (such as polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0214] In some embodiments, the negative electrode film layer may optionally further include other additives. As an example, the other additives can include thickeners, such as sodium carboxymethyl cellulose (CMC-Na), PTC thermistor materials, etc.

[0215] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. As an example of the metal foil, a copper foil may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material may include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0216] The negative electrode film layer is generally formed by coating a negative electrode slurry on the negative electrode current collector and then drying and cold pressing. The negative electrode slurry is generally formed by dispersing a negative electrode active material, an optional conductive agent, an optional binder, and other optional additives in a solvent and stirring evenly. The solvent may be N-methylpyrrolidone (NMP) or deionized water, but is not limited thereto.

[0217] The negative electrode sheet does not exclude other additional functional layers in addition to the negative electrode film layer. For example, in some embodiments, the negative electrode sheet of the present application may further include a conductive bottom coating (e.g., composed of a conductive agent and a binder) disposed on the surface of the negative electrode current collector and sandwiched between the negative electrode current collector and the negative electrode film layer; in some embodiments, the negative electrode sheet of the present application may further include a protective layer covering the surface of the negative electrode film layer.

[0218] When the battery cell is a lithium metal battery cell, the negative electrode sheet may not include a negative electrode active material capable of extracting and inserting active ions. For example, in some embodiments, the negative electrode sheet may include a lithium sheet or a lithium alloy sheet; in other embodiments, the negative electrode sheet includes a reticular or foamed three-dimensional skeleton layer, such as foamed copper (or copper alloy), foamed nickel (or nickel alloy), copper (or copper alloy) mesh, nickel (or nickel alloy) mesh, etc.

[0219] When the battery cell is a sodium metal battery cell, the negative electrode sheet may not include a negative electrode active material capable of extracting and inserting active ions. For example, in some embodiments, the negative electrode sheet may include a sodium sheet or a sodium alloy sheet; in other embodiments, the negative electrode sheet includes a reticular or foamed three-dimensional skeleton layer, such as foamed copper (or copper alloy), foamed nickel (or nickel alloy), foamed aluminum (or aluminum alloy), copper (or copper alloy) mesh, nickel (or nickel alloy) mesh, aluminum (or aluminum alloy) mesh, etc.

[0220] [Positive Electrode Sheet]

[0221] In some alternative embodiments, the battery electrode sheet includes a positive electrode sheet, and the active material film layer includes a positive electrode active material film layer.

[0222] According to the embodiments of the present application, the porosity V1 of the first region in the positive electrode active material film layer of the positive electrode tab is less than the porosity V2 of the second region, which can improve the difference in the concentration of active ions in the pore electrolytes of the first pores and the second pores, reduce the lithium deposition caused by the inability to quickly complete lithium intercalation, and can also reduce the lithium deposition of the lithium-ion battery caused by abnormal lithium intercalation paths, improving the battery cycle capacity and battery life.

[0223] Secondly, due to the different concentrations of active ions, the battery tab also affects the fast charging performance of the battery to a certain extent. The battery tab of the present application improves the uneven concentration of active ions in the battery tab and improves the fast charging performance of the battery.

[0224] In some embodiments, the positive electrode tab includes a positive electrode current collector and a positive electrode active material film layer provided on at least one surface of the positive electrode current collector and including a positive electrode active material. For example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode active material film layer is provided on any one or both of the two opposite surfaces of the positive electrode current collector.

[0225] The positive electrode active material film layer includes a positive electrode active material, and the positive electrode active material can be a positive electrode active material known in the art for battery monomers.

[0226] For example, when the battery monomer is a lithium-ion battery monomer or a lithium metal battery monomer, the positive electrode active material may include one or more of lithium transition metal oxides, lithium-containing phosphates with an olivine structure, and their respective modified compounds. Examples of lithium transition metal oxides may include one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds. Examples of lithium-containing phosphates with an olivine structure may include one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite material of lithium manganese iron phosphate and carbon, and their respective modified compounds. The present application is not limited to these materials, and other conventionally known materials that can be used as positive electrode active materials can also be used.

[0227] In some embodiments, in order to further improve the energy density of the battery monomer, the positive electrode active material may include a general formula of Li a Ni b Co c M d O e A fOne or more of lithium transition metal oxides and their modified compounds. 0.8 ≤ a ≤ 1.2, 0.5 ≤ b < 1, 0 < c < 1, 0 < d < 1, 1 ≤ e ≤ 2, 0 ≤ f ≤ 1, M includes one or more selected from Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A includes one or more selected from N, F, S, and Cl.

[0228] As an example, the positive electrode active material may include LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 (NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), LiNi 0.80 Co 0.15 Al 0.05 O 2 , LiFePO 4 and LiMnPO 4 One or more of them.

[0229] When the battery cell is a sodium-ion battery cell or a sodium metal battery cell, the positive electrode active material may include, but is not limited to, one or more of sodium-containing transition metal oxides, polyanion materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), and Prussian blue-based materials.

[0230] As an example, the positive electrode active material may include NaFeO 2 , NaCoO 2 , NaCrO 2 , NaMnO 2 , NaNiO 2 , NaNi 1 / 2 Ti 1 / 2 O 2 , NaNi 1 / 2 Mn 1 / 2O 2 、Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O 2 、NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 、NaFePO 4 、NaMnPO 4 、NaCoPO 4 , Prussian blue materials and general formula X p M' q (PO 4 ) r O x Y 3-x In the general formula X p M' q (PO 4 ) r O x Y 3-x , 0<p≤4, 0<q≤2, 1≤r≤3, 0≤x≤2, X includes a selection from H + , Li + 、Na + , K + and NH 4 + One or more of, M' is a transition metal cation, which may be selected from one or more of V, Ti, Mn, Fe, Co, Ni, Cu and Zn, and Y is a halogen anion, which may be selected from one or more of F, Cl and Br.

[0231] The modified compounds of the above-mentioned positive electrode active materials may be the ones that undergo doping modification and / or surface coating modification on the positive electrode active materials.

[0232] In some embodiments, the positive electrode active material film layer may further include a positive electrode conductive agent. The present application has no particular restrictions on the type of the positive electrode conductive agent. As an example, the positive electrode conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0233] In some embodiments, the positive electrode active material film layer may further optionally include a positive electrode binder. The present application has no particular restrictions on the type of positive electrode binder. As an example, the positive electrode binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylic resin.

[0234] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. As an example of the metal foil, aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material can include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer can include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0235] The positive electrode active material film layer is usually formed by coating a positive electrode paste on the positive electrode current collector and then drying and cold pressing. The positive electrode paste is usually formed by dispersing a positive electrode active material, an optional conductive agent, an optional binder, and any other components in a solvent and stirring evenly. The solvent can be N-methylpyrrolidone (NMP), but is not limited thereto.

[0236] In some embodiments, the method for preparing the positive electrode active material film layer includes:

[0237] Providing a paste containing a binder, a positive electrode active material, and a conductive agent;

[0238] Drying the paste to form a positive electrode active material film layer.

[0239] In some embodiments, when the solid content of the paste ≥ 75%, the leveling property of the paste disappears, and it can be rolled into a film by a roll press; the increase in the solid content can effectively reduce the drying energy consumption and lower the production cost.

[0240] In some embodiments, based on the total mass of the positive electrode active material, the conductive agent, and the binder, the total addition amount of the binder is preferably 1-2.5 wt%, such as 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%. If the addition amount of the polymer or the binder is too low, too little binder cannot support the strength of the positive electrode active material film layer, thus unable to meet the requirements of rolling and thinning. If the addition amount of the binder is too large, the viscosity of the positive electrode active material film layer will be too large, resulting in easy sticking of the film during the rolling process and unable to perform thinning and current collector lamination.

[0241] [Preparation Method]

[0242] The preparation method of the battery electrode sheet of the present application is well-known. In some embodiments, the battery electrode sheet can be perforated using a perforating roll to achieve a pore volume in the first region smaller than that in the second region. For example, the perforating roll has perforating pins arranged in a certain pattern to achieve the regulation of the pore volume of the electrode sheet and the porosity of the first region and the second region.

[0243] In some embodiments, a battery electrode sheet including a first region and a second region with different pore volumes is mass-produced using 3D printing technology. As an example, pores with different depths of channels are mass-produced using 3D printing technology with the raw material of the negative electrode active material film layer, so that the pore volume of the first region is smaller than that of the second region, realizing the production of the negative electrode sheet.

[0244] In some embodiments, a method for preparing a battery electrode sheet includes:

[0245] Coating a slurry for preparing an active material film layer on a current collector using 3D printing to prepare a battery electrode sheet including the active material film layer; wherein, the active material film layer includes a first region and a second region located on at least one side of the first region along a first direction; the active material film layer includes a plurality of pores, the plurality of pores have openings on the surface of the active material film layer, and the plurality of pores include first pores and second pores:

[0246] The opening of the first pore is provided in the first region,

[0247] The opening of the second pore is provided in the second region, wherein,

[0248] Based on the same volume of the active material film layer, the porosity V1 of the first region is smaller than the porosity V2 of the second region.

[0249] Battery cell

[0250] In a second aspect, an embodiment of the present application provides a battery cell including the battery electrode sheet of the first aspect.

[0251] The present application does not particularly limit the type of the battery cell. For example, the battery cell can be a lithium-ion battery, a sodium-ion battery, etc. Optionally, it is a lithium-ion battery.

[0252] In some embodiments, the battery cell includes a battery electrode sheet, a separator, and an electrolyte. The battery electrode sheet includes a positive electrode sheet and a negative electrode sheet.

[0253] [Separator]

[0254] The separator is disposed between the positive electrode sheet and the negative electrode sheet, mainly serving to prevent the positive electrode and the negative electrode from short-circuiting. The present application does not particularly limit the type of the separator, and any well-known porous structure separator with good chemical stability and mechanical stability can be selected.

[0255] In some embodiments, the material of the separator may include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer are the same or different.

[0256] [Electrolyte]

[0257] In some embodiments, the battery cell includes an electrolyte. The electrolyte functions to conduct active ions between the positive electrode sheet and the negative electrode sheet. There is no specific limitation on the type of the electrolyte in this application, and it can be selected according to requirements. For example, the electrolyte can be selected from at least one of a solid electrolyte and a liquid electrolyte (i.e., an electrolyte solution).

[0258] In some embodiments, the electrolyte uses an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0259] The type of the electrolyte salt is not specifically limited and can be selected according to actual requirements. For example, the electrolyte salt includes one or more selected from lithium salts for lithium-ion batteries and sodium salts for sodium-ion batteries. As an example, the lithium salts include one or more selected from lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO 2 F 2 ), lithium difluoro(dioxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP). As an example, the sodium salts include one or more selected from NaPF 6 , NaClO 4 , NaBCl 4 , NaSO 3 CF 3 , Na(CH 3 )C 6 H 4 SO 3 .

[0260] The type of the solvent is not particularly limited and can be selected according to actual needs. In some embodiments, by way of example, the solvent may include one or more selected from ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0261] In some embodiments, the electrolyte may optionally further include additives. For example, the additives may include negative electrode film-forming additives, or may include positive electrode film-forming additives, or may also include additives capable of improving certain battery performances, such as additives for improving the overcharge performance of the battery, additives for improving the high-temperature performance of the battery, additives for improving the low-temperature power performance of the battery, and the like.

[0262] [Preparation Method]

[0263] The preparation method of the battery of the present application is well-known. In some embodiments, a battery cell can be assembled by a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte. By way of example, the positive electrode sheet, the separator, and the negative electrode sheet can be formed into an electrode assembly through a winding process and / or a stacking process, the electrode assembly is placed in an outer package, dried, and then the electrolyte is injected, and after processes such as encapsulation, standing, formation, and shaping, a battery cell is obtained. A plurality of battery cells can further be connected in series or in parallel or in a hybrid connection to form a battery module. A plurality of battery modules can also be connected in series or in parallel or in a hybrid connection to form a battery pack. In some embodiments, a plurality of battery cells can also directly form a battery pack.

[0264] In some embodiments, the battery cell may include an outer package. The outer package can be used to encapsulate the above-mentioned electrode assembly and electrolyte.

[0265] In some embodiments, the outer package of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the battery cell can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), etc.

[0266] The present application has no particular limitation on the shape of the battery cell, and it can be a flat body, a cuboid, or other shapes. For example Figure 4The battery cell 5 has a cuboid structure as an example.

[0267] In some embodiments, as Figure 5 shown, the outer package may include a housing 51 and a cover plate 53. Among them, the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 is used to cover the opening to close the receiving cavity. The electrode assembly 52 of the first aspect of the embodiment of the present application or the electrode assembly 52 prepared by the method of the second aspect of the embodiment of the present application is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. The number of electrode assemblies 52 included in the battery cell 5 can be one or several, and can be adjusted according to requirements.

[0268] The preparation method of the battery cell of the present application is well-known, and the method at least includes the steps of preparing the electrode assembly in the second aspect of the embodiment of the present application. In some embodiments, the electrode assembly can be placed in the outer package, dried and then injected with electrolyte, and after processes such as vacuum packaging, standing, forming, and shaping, the battery cell is obtained.

[0269] In a third aspect, an embodiment of the present application provides a battery, including the battery cell of the second aspect.

[0270] The battery mentioned in the embodiment of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.

[0271] In some embodiments, the battery can be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0272] In some embodiments, the battery can be a battery pack. The battery includes a box body and battery cells, and the battery cells or battery modules are accommodated in the box body.

[0273] In some embodiments, the box body can be a part of the chassis structure of a vehicle. For example, a part of the box body can become at least a part of the floor of the vehicle, or a part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0274] In some embodiments of the present application, the battery according to the present application can be assembled into a battery module or a battery. The number of battery cells included in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module or battery.

[0275] Optionally, the battery module may further include a housing having a receiving space, and multiple battery cells are accommodated in the receiving space.

[0276] In some embodiments, the above battery module can also be assembled into a battery pack, and the number of battery modules included in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0277] electrical device

[0278] Fourthly, embodiments of the present application provide an electrical device, which includes the battery in the third aspect.

[0279] The battery cell or electrical device of the present application includes the separator of the first aspect of the present application, and thus has at least the advantages of the application of the separator.

[0280] The battery cell can be used as the power source of the electrical device or as the energy storage unit of the electrical device. In some embodiments, the battery can be an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0281] In some embodiments, the electrical device can be, but is not limited to, a mobile device (such as a mobile phone, a laptop computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

[0282] Figure 6 It is a schematic diagram of an electrical device as an example. The electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirements of the electrical device for high power and high energy density, a battery pack or a battery module can be used.

[0283] Another example of the electrical device can be a mobile phone, a tablet computer, a laptop computer, etc. This electrical device usually requires being thin and light, and a battery cell can be used as the power source.

[0284] embodiment

[0285] The following embodiments more specifically describe the content disclosed in the present application. These embodiments are only for illustrative purposes, because various modifications and changes within the scope of the content disclosed in the present application are obvious to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized according to conventional methods and can be used directly without further treatment, and the instruments used in the embodiments are all commercially available.

[0286] Embodiment

[0287] Prepare the negative electrode sheet:The negative electrode slurry is prepared by dissolving active material artificial graphite, conductive agent carbon black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) in deionized water as a solvent according to a weight ratio of 96.8:0.7:1.3:1.2, and mixing them evenly. The obtained slurry is used by means of 3D printing to construct a negative electrode active material film layer with alternately long and short pore depths on a current collector copper foil of 6 μm, and then dried at 80 °C, cold-pressed, and cut to obtain a negative electrode plate. Among them, the positions of the first region and the second region in the negative electrode active material film layer are as Figure 1 shown. The areas of the first region and the second region on the negative electrode surface are 1800 mm 2 . The diameters of the openings of the first pore and the second pore are 50 microns respectively.

[0288] Preparation of battery cell

[0289] Preparation of the positive electrode plate: Nickel-cobalt-manganese (NCM) ternary material, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) are stirred and mixed evenly according to a weight ratio of 96.7:1.7:1.6, and N-methylpyrrolidone (NMP) is added as a solvent to obtain a positive electrode slurry; then the positive electrode slurry is evenly coated on the positive electrode current collector, and then dried, cold-pressed, and cut to obtain a positive electrode plate.. The obtained slurry is coated on a 13-μm aluminum foil with a surface density of 13.7 mg / cm 2 by a doctor blade, and then dried at 140 °C, cold-pressed, and cut to obtain a positive electrode plate.

[0290] Preparation of the negative electrode plate: The negative electrode plate prepared above.

[0291] Electrolyte: In a glove box under an argon atmosphere (H 2 O < 0.1 ppm, O 2 < 0.1 ppm), organic solvents ethylene carbonate (EC) / ethyl methyl carbonate (EMC) are mixed evenly according to a volume ratio of 3 / 7, and 12.5 wt% (based on the weight of the ethylene carbonate / ethyl methyl carbonate solvent) LiPF6 is added and dissolved in the above organic solvents, and stirred evenly to obtain an electrolyte.

[0292] Separator: A commercially available PP-PE copolymer microporous film with a thickness of 7 μm and an average pore diameter of 80 nm (from Zhuogao Electronic Technology Co., Ltd., model 20) is used.

[0293] The positive electrode plate, the separator, and the negative electrode plate are stacked in sequence, and the separator is placed in the middle of the positive and negative electrodes to play a role in isolation, and then wound to obtain a bare battery cell. The bare battery cell is placed in an outer package, the above electrolyte is injected and sealed to obtain a battery monomer.

[0294] Example 2-3

[0295] The difference between this embodiment and Embodiment 1 lies in that: the positions of the first region and the second region are different from those in Embodiment 1. In Embodiment 2, the positions of the first region and the second region on the negative electrode surface are as Figure 2 shown. In Embodiment 3, the positions of the first region and the second region on the negative electrode surface are as Figure 2 shown.

[0296] Embodiments 4 - 9

[0297] The difference between this embodiment and Embodiment 1 lies in that: the porosity V2 of the second region is different, and the thickness of the second pores along the negative electrode active material film layer is different.

[0298] Embodiments 10 - 14

[0299] The difference between this embodiment and Embodiment 1 lies in that: the areas of the first pores and the second pores are different, so that the porosity V1 of the first region and the porosity V2 of the second region are different.

[0300] Embodiments 14 - 17

[0301] The difference between this embodiment and Embodiment 1 lies in that: the distribution densities of the openings of the first pores and the second pores are different, so that the porosity V1 of the first region and the porosity V2 of the second region are different.

[0302] Embodiments 18 - 21

[0303] The difference between this embodiment and Embodiment 1 lies in that: the opening shapes of the first pore openings and the second pores are different. Triangles, squares, and rectangles are controlled to be of appropriate lengths so that the pore volumes of the first region and the second region are different, and the porosity V1 of the first region is less than the porosity V2 of the second region.

[0304] Embodiment 22

[0305] The difference between this embodiment and Embodiment 1 lies in the preparation of the negative electrode sheet: Graphite, active silicon - carbon particles, conductive agent carbon black, binder styrene - butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) are dissolved in deionized water according to a weight ratio of 86.8:10:0.7:1.3:1.2. Among them, the mass content of silicon element in the active silicon - carbon particles is 10%. After mixing evenly, the obtained negative electrode slurry is prepared. The obtained slurry is coated on a 6 - μm current collector copper foil, then dried at 80°C, cold - pressed, and cut to obtain the negative electrode sheet.

[0306] Comparative Example 1

[0307] The difference between this comparative example and Example 1 lies in the different preparation methods of the negative electrode sheet. Preparation of the negative electrode sheet: The active material artificial graphite, conductive agent carbon black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) were dissolved in deionized water as the solvent in a weight ratio of 96.8:0.7:1.3:1.2, and after being mixed evenly, the resulting negative electrode slurry was prepared. The obtained slurry was coated on a 6-μm current collector copper foil, then dried at 80°C, cold-pressed, and cut to obtain the negative electrode sheet. No additional punching was performed on the negative electrode sheet, and for the first region and the second region at the position of Example 1, the porosity V1 was equal to the porosity V2.

[0308] Comparative Example 2

[0309] The difference between this comparative example and Example 1 lies in the different preparation of the negative electrode sheet: Graphite, active material silicon-carbon particles, conductive agent carbon black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) were dissolved in deionized water as the solvent in a weight ratio of 86.8:10:0.7:1.3:1.2, wherein the mass content of silicon element in the active material silicon-carbon particles was 10%, and after being mixed evenly, the resulting negative electrode slurry was prepared. The obtained slurry was coated on a 6-μm current collector copper foil, then dried at 80°C, cold-pressed, and cut to obtain the negative electrode sheet. No additional punching was performed on the negative electrode sheet, and relative to the first region at the position of Example 1, the porosity V1 was equal to the porosity V2 of the second region.

[0310] Testing section

[0311] The battery electrode sheets and batteries obtained in the examples and comparative examples were tested as follows.

[0312] (1) Lithium plating test

[0313] Constant current charge at 2C to 4.4V, stand still for 5 min, then constant current discharge at 1C to 2.5V. The above is one charge-discharge cycle of the battery. After 10 cycles, constant voltage charge at 4.4V until the current is 0.05C. Disassemble the battery in a dry environment. A golden-yellow surface of the battery electrode sheet indicates no lithium plating, and the appearance of a silver-white area indicates lithium plating. Through experimental detection, compared with the battery electrode sheets in the comparative examples, the battery electrode sheets with the second porosity in the examples had more golden-yellow areas and fewer silver-white areas on the surface, while the silver-white areas in the comparative examples were more, indicating that the lithium plating phenomenon of the electrode sheets in the examples of the present application was improved.

[0314] (2) 800cls cycle capacity retention rate: Room temperature 2C cycle test of battery cells: Take the battery cells in the examples and comparative examples, with at least 2 parallel samples for each example. First, place the battery cells in a constant temperature environment of 25°C for 1 hour. Then, perform constant current charging on the battery at a charging rate of 2C. After charging to 4.4V, switch to constant voltage charging, let it stand for 10 min, and then discharge the battery at a constant current with a discharge rate of 1C until 2.5V, and let it stand for 5 minutes. The above process is cycled for a specific number of cycles. Calculation of capacity retention rate: Capacity retention rate at the 800th cycle = (Discharge capacity at the 800th cycle / Discharge capacity at the second cycle) × 100%.

[0315] The test results are shown in Table 1.

[0316] It can be seen from the test results in Table 1 that by setting the respective depths, shapes, and distribution densities of the first pores and the second pores in the examples, the porosity of the first region is less than that of the second region. By setting the first pores and the second pores, under high-rate charging cycles, the capacity retention rate at 800cls is high. The reason is that the first pores and the second pores improve the lithium-ion diffusion kinetics, enhance the charge-discharge ability, reduce the precipitation of active lithium ions, and improve the cycle life and cycle capacity retention rate of the battery.

[0317] It can also be seen from the test results in Table 1 that in Comparative Example 1, no additional first pores and second pores were set in the corresponding first region and second region, and the porosity of the first region was equal to that of the second region. It was found that lithium plating occurred in some corresponding second regions, and its cycle capacity retention rate was relatively low compared to the examples, indicating that the battery electrode sheet of the present application improves the problem of active ion precipitation and increases the cycle capacity retention rate and service life of the battery.

[0318] It should be noted that the present application is not limited to the above embodiments. The above embodiments are only examples, and embodiments with the same composition and the same effect as the technical idea within the scope of the technical solution of the present application are included in the technical scope of the present application. In addition, within the scope of not departing from the gist of the present application, various modifications that those skilled in the art can think of to the embodiments, and other ways constructed by combining some constituent elements of the embodiments are also included in the scope of the present application.

[0319]

[0320]

Claims

1. A battery electrode, characterized in that, it includes: a current collector and an active material film layer disposed on at least one side of the current collector, the active material film layer including a first region and a second region located on at least one side of the first region along a first direction; the active material film layer contains a plurality of pores, the plurality of pores having openings on the surface of the active material film layer, the plurality of pores including first pores and second pores: the openings of the first pores are disposed in the first region, the openings of the second pores are disposed in the second region, wherein, based on the same volume of the active material film layer, the porosity V1 of the first region is less than the porosity V2 of the second region.

2. The battery electrode according to claim 1, characterized in that, the battery electrode includes a negative electrode, and the active material film layer includes a negative active material film layer.

3. The battery electrode according to claim 1, characterized in that, the cross-sectional areas of the channels in the first pores and the second pores are the same.

4. The battery electrode according to claim 3, wherein, the depth d1 of the channels of more than 80% of the first pores located in the first region extending along the thickness direction of the active material film layer is less than the depth d2 of the channels of more than 80% of the second pores located in the second region extending along the thickness direction of the active material film layer.

5. The battery electrode according to any one of claims 1 to 4, characterized in that, the battery electrode satisfies at least one of the following conditions: 1) Along the thickness direction of the active material film layer, the depth d1 of the channels of the first pores extending along the thickness direction of the active material film layer is less than the depth d2 of the channels of the second pores extending along the thickness direction of the active material film layer; 2) 0.01:1 ≤ d1 / D < 1:1, where the thickness of the active material film layer is represented by D; along the thickness direction of the active material film layer, the depth of the channels of the first pores along the thickness direction of the active material film layer is represented by d1; 3) 0.01:1 ≤ d2 / D < 1:1, where the thickness of the active material film layer is represented by D; the depth of the channels of the second pores along the thickness direction of the active material film layer is represented by d2; 4) Along the thickness direction of the active material film layer, the depth d1 of the channels of the first pores is 1 μm to 80 μm; 5) Along the thickness direction of the active material film layer, the depth d2 of the channels of the second pores is 1 μm to 80 μm; 6) Along the thickness direction of the active material film layer, the length difference between the depth d1 of the channels of the first pores and the depth d2 of the channels of the second pores is 0 μm to 50 μm.

6. The battery electrode according to any one of claims 1 to 4, characterized in that, the depth difference of the channels of any two adjacent pores along the thickness direction of the active material film layer in the first direction is 0 to 45 μm.

7. The battery electrode according to any one of claims 1 to 4, characterized in that, the distance between any two adjacent pores in the first direction is 0.1 mm to 300 mm; and / or, The distance between any two adjacent pores in the second direction is 0.1 mm to 300 mm, and the second direction intersects the first direction; and / or, The distribution density of the openings of the pores in the active material film layer is 10 to 100 openings per square centimeter.

8. The battery electrode sheet according to any one of claims 1 to 4, characterized in that The first pore and the second pore satisfy any one of the following conditions: 1) The ratio of the area of any one of the first pores or any one of the second pores on the surface of the active material film layer to the area of the active material film layer is (0.0006 to 0.05):1; 2) The first pore and the second pore are circular in a cross-section parallel to the active material film layer, and the average diameter of the pores is 20 μm to 100 μm; 3) The first pore and the second pore are square in a cross-section parallel to the active material film layer, and the average side length of the pores is 20 μm to 100 μm; 4) The first pore and the second pore are trapezoidal in a cross-section parallel to the active material film layer, and the average height of the trapezoid is 20 μm to 100 μm; 5) The first pore and the second pore are rectangular in a cross-section parallel to the active material film layer, and the average length of the longer side of the rectangle is 20 μm to 100 μm.

9. The battery electrode sheet according to any one of claims 1 to 4, characterized in that The active material film layer satisfies at least one of the following conditions: 1) The tap density of the active material film layer satisfies 1.3 m 2 / g to 1.9 m 2 / g; 2) The porosity V1 of the first region is 20% to 35%; 3) The porosity V2 of the second region is 23% to 40%; 4) The active material film layer includes a third region. Optionally, the porosity V3 of the third region is 19% - 34%.

10. The battery electrode sheet according to any one of claims 1 to 4, characterized in that The active material film layer satisfies any one of the following conditions: 1) The first direction is the direction from the first region to the battery tab; 2) The first direction is a direction intersecting the direction from the first region to the battery tab; 3) The ratio of the projected area of the first region on the current collector to the projected area of the active material film layer on the current collector is 3% to 20%; 4) The ratio of the projected area of the first region on the current collector to the projected area of the active material film layer on the current collector is 15% to 50%.

11. A battery cell, characterized in that it includes the battery electrode sheet according to any one of claims 1 to 10.

12. A battery, characterized in that it includes the battery cell according to claim 11.

13. An electrical device, characterized in that it includes the battery according to claim 12.

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