Pole piece and preparation method thereof, battery and electric equipment

Abstract

The invention relates to the technical field of batteries, in particular to a pole piece and a preparation method thereof, a battery and electric equipment.The pole piece comprises a current collector and an active substance layer arranged on the surface of at least one side of the current collector, and at least one groove is formed in the surface, away from the current collector, of the active substance layer; and the edge of at least one side of the groove in the length direction is provided with an accumulated dressing. According to the pole piece, most of the active substances removed by forming the groove are stacked on the edge of at least one side of the groove (namely the stacked dressing), so that effective utilization of the active substances is facilitated, meanwhile, more reaction surfaces are provided, high surface density of the pole piece can be kept, and the structural integrity and performance of the pole piece can be maintained; therefore, the contact area and the infiltration degree of the pole piece and electrolyte in the battery adopting the pole piece are increased, the interface resistance is reduced, the charge transfer efficiency is improved, the charging speed is increased, the energy density of the battery is improved, and the service life is prolonged.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and more specifically, to a pole piece and a method for preparing the pole piece, a battery and an electrical device. Background Art

[0002] As an important component of lithium-ion batteries, the design and preparation of electrode plates are the key to improving battery performance, and the surface texture of electrode materials can affect electrochemical properties including charging speed, capacity and battery life. Increasing the specific surface area of ​​electrode plates can increase the contact area and wetting degree between the plates and the electrolyte, which helps to reduce interface resistance and improve charge transfer efficiency, thereby speeding up charging, increasing battery energy density and extending service life.

[0003] In the related technologies, there are many methods for processing surface textures, including chemical etching, laser texturing, and electrospark machining. Although surface textures can be formed to a certain extent, these methods often have problems such as high cost, complex process, or low efficiency. For example, laser texturing is expensive, and molten beads may be produced during the process, resulting in poor processing consistency. Chemical etching may cause environmental pollution. The control accuracy of electrospark machining is low, and it may damage the structure of the active material and affect the electrochemical stability of the battery cell. Therefore, the technology related to the pole piece still needs to be improved. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the present invention provides a pole piece with extremely large specific surface area, high surface density and good structural stability, a preparation method thereof, a battery and an electric device.

[0005] The first aspect of the present application provides a pole piece. According to an embodiment of the present application, the pole piece includes: a current collector and an active material layer arranged on at least one side surface of the current collector, the surface of the active material layer away from the current collector is provided with at least one groove, and at least one side edge in the length direction of the groove has a deposited dressing. In the pole piece, most of the active materials removed due to the formation of the groove are deposited on at least one side edge of the groove (i.e., deposited dressing), which helps to effectively utilize the active materials, and at the same time provides more reaction surfaces, which is conducive to maintaining the pole piece with a high surface density, and maintaining the structural integrity and performance of the pole piece, thereby increasing the contact area and wetting degree between the pole piece and the electrolyte in the battery using the pole piece, which helps to reduce the interface resistance, improve the charge transfer efficiency, thereby accelerating the charging speed, increasing the battery energy density and extending the service life.

[0006] According to an embodiment of the present application, the stacked dressing is continuously stacked along the edge of the groove, thereby facilitating full utilization of the active substance and maintaining a high surface density.

[0007] According to an embodiment of the present application, the height of the stacked dressing is 3.5 μm to 11 μm, thereby facilitating full utilization of the active substance and maintaining a relatively high surface density.

[0008] According to an embodiment of the present application, the depth of the groove accounts for 30% to 80% of the thickness of the active material layer. According to an embodiment of the present application, the depth of the groove accounts for 40% to 60% of the thickness of the active material layer. Thus, a higher specific surface area can be provided while maintaining the structural stability of the pole piece.

[0009] According to an embodiment of the present application, the width of the groove is 20 μm to 260 μm. Within this range, it is beneficial to provide a higher specific surface area.

[0010] According to an embodiment of the present application, the cross-sectional shape of the groove is U-shaped or V-shaped, thereby having a higher specific surface area and being easy to prepare.

[0011] According to an embodiment of the present application, the electrode sheet includes at least one of a positive electrode sheet and a negative electrode sheet.

[0012] The second aspect of the present application provides a method for preparing the aforementioned pole piece. According to an embodiment of the present application, the method includes: determining a reference position of a tool; adjusting the position of the tool to a predetermined depth deep into the active material layer; causing the tool to cut the active material layer along a predetermined path and according to the predetermined depth to form a groove on the active material layer, and at least one side edge in the length direction of the groove has a deposited dressing. The method changes the surface texture of the pole piece by physical shearing rather than chemical or thermal energy action, and most of the cut active materials are deposited on both sides of the groove, which is conducive to the effective utilization of the active material, avoiding the reduction of the surface density of the material due to high-temperature melting or gasification, and is conducive to maintaining the structural integrity and performance of the battery pole piece, and the process is simple, the cost is low, and the thermal stability and chemical stability of the active material are less affected, which is suitable for large-scale production, and the prepared pole piece can significantly improve the degree of electrolyte infiltration, thereby increasing the effective contact area between the pole piece and the electrolyte, reducing the internal resistance of the battery, and improving the charging and discharging efficiency.

[0013] According to an embodiment of the present application, a surfactant is provided on the cutting tool, thereby reducing damage to active substances during the cutting process, reducing the impact of tool wear, and helping to form uniform, high-quality grooves with smooth sidewall surfaces.

[0014] According to an embodiment of the present application, the surfactant includes at least one of an organic silicon surfactant and a phospholipid surfactant. Thus, the effect of reducing friction, slowing tool wear and improving groove quality during the cutting process is better.

[0015] According to an embodiment of the present application, the tool is connected to an intelligent control device, and the intelligent control device is used to control the movement of the tool. Thus, the tool's motion trajectory, speed, pressure and other parameters can be accurately controlled by computer programming to achieve high-precision and repeatable groove processing.

[0016] According to an embodiment of the present application, the tool includes a disc shear. Specifically, the disc shear can be performed without damaging the basic structure of the electrode material. Most of the cut active materials are accumulated on both sides of the groove, which helps to effectively utilize the active materials and provides more reaction surfaces. The equipment is easy to obtain, the cost is low, and automatic control can be achieved. Compared with traditional laser cutting technology, the use of disc shear cutting technology significantly reduces processing costs. This improvement in cost-effectiveness is of great significance to large-scale production.

[0017] According to an embodiment of the present application, the circular shear adopts at least one of a 60° double-edge tool, a 60° single-edge tool and a 30° single-edge tool.

[0018] According to an embodiment of the present application, a method for preparing a pole piece includes: determining the zero point position of the circular shear using a standard sheet of known thickness; adjusting the circular shear to the predetermined depth position according to the thickness of the pole piece; cutting the pole piece using the circular shear while the pole piece is unwinding; and winding up the cut pole piece.

[0019] According to an embodiment of the present application, the pole piece unwinding tape speed is 20 m / min to 120 m / min. Within the above tape speed range, it is beneficial to obtain clear grooves with distinct edges, and the processing efficiency is high.

[0020] The third aspect of the present application provides a battery. According to an embodiment of the present application, the battery includes the pole piece described above, or the pole piece prepared by the method described above.

[0021] In a fourth aspect of the present application, an electric device is provided. According to an embodiment of the present application, the electric device includes the battery described above. The electric device has all the features and advantages of the battery described above, which will not be described one by one here. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the cross-sectional structure of a pole piece according to an embodiment of the present application.

[0023] Figure 2 It is a schematic diagram of the planar structure of a pole piece according to an embodiment of the present application.

[0024] Figure 3 It is a structural schematic diagram of a disc shear in one embodiment of the present application using a 60° double-edged tool to cut pole pieces.

[0025] Figure 4 It is a schematic structural diagram of a disc shear in one embodiment of the present application using a 60° single-edge blade tool to cut pole pieces.

[0026] Figure 5 It is a schematic structural diagram of a disc shear in one embodiment of the present application using a 30° single-edge blade tool to cut pole pieces.

[0027] Figure 6 It is a schematic diagram of the structure of a disc shear cutting a pole piece in one embodiment of the present application.

[0028] Figure 7 It is a schematic diagram of the cutting distance of a disc shear in cutting a pole piece according to an embodiment of the present application.

[0029] Figure 8 These are confocal microscopy images of Examples 2, 4, and 6 of the present application.

[0030] Fig. 9 These are the confocal microscopic images, confocal 3D microscopic images and groove depth analysis result diagrams of the pole pieces in Examples 1, 2 and 3 of the present application.

[0031] Fig.10 This is a schematic diagram of the disc shear structure of an embodiment of the present application.

[0032] Reference numerals:

[0033] 10: Pole piece 11: Current collector 12: Active material layer 13: Groove 14: Accumulated dressing 20: Cutting tool DETAILED DESCRIPTION

[0034] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0035] In a first aspect of the present application, a pole piece is provided. According to an embodiment of the present application, referring to Figure 1The pole piece 10 comprises: a current collector 11 and an active material layer 12 disposed on at least one side surface of the current collector, wherein the surface of the active material layer 12 away from the current collector 11 is provided with at least one groove 13, and at least one side edge in the length direction of the groove has a deposited dressing 14. In the pole piece, most of the active materials removed due to the formation of the groove are deposited on at least one side edge of the groove (i.e., deposited dressing), which is conducive to the effective utilization of the active materials, and at the same time provides more reaction surfaces, which is conducive to maintaining the pole piece with a high surface density, and maintaining the structural integrity and performance of the pole piece, thereby increasing the contact area and wetting degree between the pole piece and the electrolyte in the battery using the pole piece, which is conducive to reducing the interface resistance, improving the charge transfer efficiency, thereby accelerating the charging speed, improving the battery energy density and extending the service life.

[0036] According to the embodiment of the present invention, the accumulated dressing is continuously distributed along the edge of the groove, thereby facilitating full utilization of the active material and maintaining a high surface density of the electrode.

[0037] According to the embodiments of the present application, referring to Figure 1 , the height H1 of the accumulated dressing 14 can be 3.5μm to 11μm, specifically 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, 10μm, 10.5μm, 11μm, etc. Thus, most of the film material is accumulated on both sides of the groove, which is conducive to maintaining a higher surface density of the pole piece, as well as the structural integrity and performance of the pole piece.

[0038] According to the embodiments of the present application, referring to Figure 1 , the depth H2 of the groove accounts for 30% to 80% of the thickness H of the active material layer. In some embodiments, the depth H2 of the groove accounts for 40% to 60% of the thickness H of the active material layer. As an example, the depth H2 of the groove may account for 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% and so on of the thickness H of the active material layer. Within the above range, it can effectively increase the specific surface area of ​​the active material layer, increase the contact area and wetting degree of the pole piece and the electrolyte, and can also help reduce the interface resistance and improve the charge transfer efficiency, thereby speeding up the charging speed; if the depth of the groove is too shallow, the specific surface area of ​​the pole piece cannot be effectively increased, and if the depth of the groove is too deep, it may damage the collector structure, so that the pole piece cannot effectively maintain the structural integrity.

[0039] According to the embodiments of the present application, referring to Figure 1The width W of the groove can be 20 μm to 260 μm, such as 20 μm, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, 200 μm, 220 μm, 260 μm, etc. Within the above width range, the specific surface area of ​​the pole piece can be effectively increased without reducing the surface density of the pole piece too much, thereby improving the energy density and service life of the battery using the pole piece.

[0040] According to the embodiments of the present application, the specific shape of the cross section of the groove is not particularly limited, for example, including but not limited to square, rectangular, U-shaped, V-shaped, inverted trapezoidal or other regular or irregular shapes. In some specific embodiments, the cross-sectional shape of the groove can be U-shaped or V-shaped. This is conducive to increasing the specific surface area of ​​the pole piece and facilitating processing.

[0041] It is understood that the number of grooves is not particularly limited and can be selected according to actual needs. Figure 2 , the active material 12 may include a plurality of grooves 13 arranged at intervals. The shape of the grooves on the active material layer (i.e., the overall shape of the grooves seen when looking down at the active material layer) is not particularly limited and can be flexibly selected according to actual needs and preparation conditions. As an example, Figure 2 The figure shows a case where the grooves are multiple elongated rectangles arranged at intervals.

[0042] It can be understood that in the electrode sheet, active material layers are usually provided on both sides of the current collector. The above-mentioned grooves may be provided only on the active material layer on one side of the current collector, while the above-mentioned grooves may not be provided on the active material layer on the other side; or the above-mentioned grooves may be provided in the active material layers on both sides of the current collector.

[0043] According to an embodiment of the present application, the electrode sheet includes at least one of a positive electrode sheet and a negative electrode sheet. Specifically, the positive electrode sheet may generally include a positive electrode current collector and a positive electrode active material layer disposed on at least one side surface of the positive electrode current collector, and the positive electrode active material layer may include a positive electrode active material, a binder and a conductive agent, wherein the positive electrode active material may include lithium iron phosphate, lithium iron manganese phosphate, ternary materials (nickel cobalt manganese ternary positive electrode materials, nickel cobalt aluminum ternary positive electrode materials, etc.), lithium cobaltate, lithium manganate, etc. The negative electrode sheet may generally include a negative electrode current collector and a negative electrode active material layer disposed on at least one side surface of the negative electrode current collector, and the negative electrode active material layer may include a negative electrode active material, a binder and a conductive agent, wherein the negative electrode active material may include graphite, silicon-carbon materials, silicon-oxygen materials, etc.

[0044] The second aspect of the present application provides a method for preparing the aforementioned pole piece. According to an embodiment of the present application, the method includes: determining a reference position of a tool; adjusting the position of the tool to a predetermined depth deep into the active material layer; causing the tool to cut the active material layer along a predetermined path and according to the predetermined depth to form a groove on the active material layer, and at least one side edge in the length direction of the groove has a deposited dressing. The method changes the surface texture of the pole piece by physical shearing rather than chemical or thermal energy action, and most of the cut active materials are deposited on both sides of the groove, which is conducive to the effective utilization of the active material, avoiding the reduction of the surface density of the material due to high-temperature melting or gasification, and is conducive to maintaining the structural integrity and performance of the battery pole piece, and the process is simple, the cost is low, and the thermal stability and chemical stability of the active material are less affected, which is suitable for large-scale production, and the prepared pole piece can significantly improve the degree of electrolyte infiltration, thereby increasing the effective contact area between the pole piece and the electrolyte, reducing the internal resistance of the battery, and improving the charging and discharging efficiency.

[0045] Specifically, whether an accumulation dressing is formed on the edge of the groove can be adjusted according to the shape of the tool. As an example, the side of the tool with a beveled edge is conducive to the formation of an accumulation dressing. In actual operation, a suitable tool shape can be selected as needed to form an accumulation dressing on one side or both sides of the length direction of the groove.

[0046] According to an embodiment of the present application, a surfactant is provided on the cutting tool, thereby reducing damage to active substances during the cutting process, reducing the impact of tool wear, and helping to form uniform, high-quality grooves with smooth sidewall surfaces.

[0047] According to an embodiment of the present application, the surfactant includes at least one of an organic silicon surfactant and a phospholipid surfactant. Thus, the effect of reducing friction, slowing tool wear and improving groove quality during the cutting process is better.

[0048] According to an embodiment of the present application, the tool is connected to an intelligent control device, and the intelligent control device is used to control the movement of the tool. Thus, the tool's motion trajectory, speed, pressure and other parameters can be accurately controlled by computer programming to achieve high-precision and repeatable groove processing.

[0049] Specifically, the intelligent control device can be a device such as a computer that can achieve automatic control, and this application has no particular limitation.

[0050] According to an embodiment of the present application, the tool includes a disc shear. Specifically, the disc shear can be performed without damaging the basic structure of the electrode material. Most of the cut active materials are accumulated on both sides of the groove, which helps to effectively utilize the active materials and provides more reaction surfaces. The equipment is easy to obtain, the cost is low, and automatic control can be achieved. Compared with traditional laser cutting technology, the use of disc shear cutting technology significantly reduces processing costs. This improvement in cost-effectiveness is of great significance to large-scale production.

[0051] Furthermore, the parameters of the disc shear (shearing depth, angle, spacing, etc.) can be accurately adjusted, and the size and distribution of the grooves can be precisely controlled, making the microstructure design of the pole piece more flexible and preventing the problem of inconsistent molten beads and line depth under high-power laser cutting. Specifically, the shape and sharpness of the tool determine the cross-sectional shape of the groove, and the degree of the tool's edge is positively correlated with the groove width. The greater the degree of edge sharpness, the wider the groove width, thereby achieving customized adjustment of the groove on the pole piece surface.

[0052] According to the embodiment of the present application, the circular shear adopts a 60° double-edged blade (refer to Figure 3 ), 60° single edge (refer to Figure 4 ) and 30° single edge (refer to Figure 5 ) at least one of.

[0053] According to an embodiment of the present application, a method for preparing a pole piece may include: determining the zero point position of the circular shear using a standard sheet of known thickness; adjusting the circular shear to the predetermined depth position according to the thickness of the pole piece; cutting the pole piece using the circular shear while the pole piece is unwinding; and winding up the cut pole piece.

[0054] For details, see the schematic diagram of the structure of the disc shear cutting the pole piece. Figure 6 , the schematic diagram of the disc shearing cut H3 (i.e. the above-mentioned predetermined depth) is shown in Figure 7 . For a schematic diagram of the disc shear structure, see Fig.10 , Fig.10 (a) is a schematic diagram of the disc shear plane structure. Fig.10 (b) is Fig.10 (a) is a schematic diagram of the cross-sectional structure along line AA. Fig.10 (c) is Fig.10 Schematic diagram of the enlarged area indicated by the circle in (b).

[0055] According to an embodiment of the present application, the tape speed of the pole piece unwinding is 20m / min to 120m / min, specifically 20m / min, 25m / min, 30m / min, 35m / min, 40m / min, 45m / min, 50m / min, 55m / min, 60m / min, 65m / min, 70m / min, 75m / min, 80m / min, 85m / min, 90m / min, 95m / min, 100m / min, 110m / min, 120m / min, etc. Within the above tape speed range, it is conducive to obtaining clear grooves with distinct edges, and the processing efficiency is high.

[0056] As an example, the steps of preparing a pole piece using a disc shear may include:

[0057] (1) Calibration (i.e. determining the zero point position of the circular shear)

[0058] The tool calibration step is the basis for ensuring that the disc shear is correctly aligned with the electrode to be processed, which is directly related to the accuracy and quality of subsequent processing. As an example, the tool can be aligned with the bottom surface of the electrode as the zero point of the tool, which can be set manually or using high-precision instruments such as three-dimensional measuring instruments and laser rangefinders.

[0059] (2) Choose the right tool

[0060] The shape and sharpness of the disc shear determine the cross-sectional shape, width, etc. of the groove. You can choose a suitable tool that meets the conditions according to the design requirements.

[0061] (3) Adjust the tool depth

[0062] The depth of the disc shear penetrating into the active material layer directly determines the depth, width and shape of the groove. The depth of the disc shear penetrating into the electrode sheet can be adjusted by precisely controlling the micrometer. As an example, the control accuracy can be ±0.01mm.

[0063] (4) Tape transport

[0064] In this step, the disc shear forms a groove on the pole piece by adjusting the mechanical friction force. Parameters such as the magnitude of the friction force, the pole piece travel speed (i.e., the tape speed), and the contact angle between the disc shear and the pole piece can be controlled in this process.

[0065] (5) Rolling

[0066] The speed and tension control during the winding process needs to be synchronized with the material processing speed to ensure the integrity of the pole piece after processing and avoid physical damage caused by improper tension.

[0067] It can be understood that in this step, the cut pole pieces can be collected by stacking.

[0068] The third aspect of the present application provides a battery. According to an embodiment of the present application, the battery includes the pole piece described above, or the pole piece prepared by the method described above. In the battery, the effective contact area between the pole piece and the electrolyte is large, the electrolyte infiltration degree is high, the internal resistance of the battery is low, the charging and discharging efficiency is high, and the energy density is high.

[0069] It is understood that the specific type of the battery is not particularly limited, and it can be a lithium battery, a sodium battery, etc., for example, including but not limited to lithium ion batteries, lithium metal batteries, sodium ion batteries, etc. The specific shape of the above-mentioned battery can be square, cylindrical, and other regular or irregular shapes; the outer packaging of the battery can be a hard shell (such as a steel shell, a hard plastic shell, etc.), or a soft shell (such as an aluminum-plastic film, a bag-type soft shell, etc.). The above-mentioned battery can be a battery cell, or a secondary battery assembled from multiple battery cells, or a battery module, a battery pack, etc. that is further assembled.

[0070] It can be understood that in addition to the aforementioned pole piece, the above-mentioned battery may also include a separator, an electrolyte (including an electrolyte, a semi-solid electrolyte, a solid electrolyte, etc.) and an outer package. Taking the electrolyte as an example, in the battery, the positive pole piece, the separator and the negative pole piece are stacked in sequence, and an electrode assembly is made by winding or lamination process, and the electrode assembly and the electrolyte can be contained in the outer package.

[0071] In a fourth aspect of the present application, an electric device is provided. According to an embodiment of the present application, the electric device includes the battery described above. The electric device has all the features and advantages of the battery described above, which will not be described one by one here.

[0072] According to an embodiment of the present application, the power-consuming device may include 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 and a satellite, an energy storage system, etc., but is not limited thereto. The battery may be used as a power source for the power-consuming device, or may be used as an energy storage unit for the power-consuming device.

[0073] It can be understood that in addition to the battery mentioned above, the electrical equipment may also include necessary structures and components of conventional electrical equipment. Taking electric vehicles as an example, they may include necessary structures and components such as body, windows, chassis, engine, seats, tires, etc., which will not be elaborated here.

[0074] The embodiments of the present application are described in detail below.

[0075] Example 1

[0076] ① Take a 0.1mm standard thickness sheet (a standard positive electrode sheet with a known thickness of 0.1mm or a PVC film with a thickness of 0.1mm), fix a 60° single-edged circular scissors, and gradually lower the tool until the circular scissors touch the standard thickness sheet, and record the micrometer reading at this time.

[0077] ② Lower the tool by 0.1mm, select the circular shear as the zero depth, and set the micrometer reading to 0.

[0078] ③ Raise the tool, select the electrode with a single-sided active material layer thickness of 78μm for unwinding, and lower the tool depth to 25% (20μm) of the single-sided active material layer thickness (i.e., the cutting amount is 25%).

[0079] ④ According to the tape speed of 25m / min, the tool is controlled to cut the electrode according to the predetermined depth and predetermined path to form a groove.

[0080] Example 2

[0081] Same as Example 1, except that the tool depth is adjusted to 50% (40 μm) of the thickness of the single-sided active material layer.

[0082] Example 3

[0083] Same as Example 1, except that the tool depth is adjusted to 77% (60 μm) of the thickness of the single-sided active material layer.

[0084] Example 4

[0085] Same as Example 1, except that the disc scissors are 60° double-edged disc scissors.

[0086] Example 5

[0087] Same as Example 2, except that the disc scissors are 60° double-edged disc scissors.

[0088] Example 6

[0089] Same as Example 3, except that the disc scissors are 60° double-edged disc scissors.

[0090] Example 7

[0091] Same as Example 1, except that the circular scissors are 30° single-edge circular scissors.

[0092] Example 8

[0093] Same as Example 2, except that the circular scissors are 30° single-edge circular scissors.

[0094] Example 9

[0095] Same as Example 3, except that the circular scissors are 30° single-edge circular scissors.

[0096] Morphology observation and detection:

[0097] Take the pole piece after cutting with a disc scissors, cut a 3 cm × 3 cm square pole piece with a scalpel, place it under a confocal microscope for observation, and take a confocal microscopic image at a magnification of 480 times. The confocal microscopic images of the pole pieces in Example 2, Example 4 and Example 6 are shown in Figure 8 , Figure 8 In the figure, a is the confocal microscopic image of the pole piece in Example 2, b is the confocal microscopic image of the pole piece in Example 4, and c is the confocal microscopic image of the pole piece in Example 6.

[0098] Select a contour line perpendicular to the long side of the groove in the confocal microscopy image, and use "contour measurement" to analyze the depth of the groove. "Contour measurement" is based on laser scanning and optical sectioning technology. It excludes light from non-focal planes through conjugate apertures to obtain high-definition two-dimensional graphics; the lens system focuses the laser beam to different depths of the sample, and the three-dimensional morphology of the sample can be synthesized by processing the reflected light detection data at different depths. The confocal microscopy images, confocal 3D microscopy images and groove depth analysis results of the pole pieces in Examples 1, 2 and 3 are shown in Figure 1. Fig. 9 . Fig. 9 In the figure, a is the confocal microscopy images of the pole pieces in Example 1, Example 2 and Example 3 from left to right, b is the confocal 3D microscopy images of the pole pieces in Example 1, Example 2 and Example 3 from left to right, and c is the groove depth analysis result diagram of the pole pieces in Example 1, Example 2 and Example 3 from left to right.

[0099] From the test results, it can be seen that one side of the 60° single-edged blade tool and the 30° single-edged blade tool is vertical, and the groove produces accumulated dressing at the corresponding beveled edge; both sides of the 60° double-edged blade are beveled, so the groove produces accumulated dressing on both sides. For the 60° single-edged blade disc shear, when the cutting amount is 25%, the accumulated dressing height is 3.5μm and the groove depth is 4.1μm. At this time, most of the active substances after cutting remain on the pole piece, which is conducive to the effective utilization of the active substances. When the cutting amount is 50%, the groove depth reaches 30.7μm, which greatly increases the specific surface area of ​​the pole piece while ensuring that the basic structure of the pole piece is not damaged. When the cutting amount is 77%, the groove depth is 59.0μm, and the average groove width is 256.4±4.3μm. At this time, the groove depth and width are extremely large, which can provide a reaction hotbed for special pole piece designs such as thermal management improvement, stress release or inner coating. This can also achieve a wide range of width changes by controlling the amount of cutting. When the cutting amount is 25%, 50%, and 77%, the average width of the notch is 23.4±1.0μm, 126.6±1.8μm, and 256.4±4.3μm, respectively.

[0100] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0101] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A pole piece, characterized in that: include: A current collector and an active material layer arranged on at least one side surface of the current collector, wherein the surface of the active material layer away from the current collector is provided with at least one groove, and at least one side edge of the groove in the length direction has a stacked dressing.

2. The pole piece according to claim 1, characterized in that: The accumulation dressing is accumulated continuously along the edge of the groove.

3. The pole piece according to claim 1, characterized in that: The height of the stacked dressing is 3.5 μm to 11 μm.

4. The pole piece according to claim 1, characterized in that: The depth of the groove accounts for 30% to 80% of the thickness of the active material layer.

5. The pole piece according to claim 1, characterized in that: The depth of the groove accounts for 40% to 60% of the thickness of the active material layer.

6. The pole piece according to claim 1, characterized in that: The width of the groove is 20 μm to 260 μm.

7. The pole piece according to claim 1, characterized in that: The cross-sectional shape of the groove is U-shaped or V-shaped.

8. The pole piece according to claim 1, characterized in that: The electrode sheet includes at least one of a positive electrode sheet and a negative electrode sheet.

9. A method for preparing a pole piece according to any one of claims 1 to 8, characterized in that: include: Determine the tool reference position; Adjust the position of the tool to a predetermined depth into the active material layer; The cutter is made to cut the active material layer along a predetermined path and at a predetermined depth to form a groove on the active material layer, and at least one side edge of the groove in a length direction has accumulated dressing.

10. The method according to claim 9, characterized in that The cutting tool is provided with a surfactant.

11. The method according to claim 10, characterized in that The surfactant includes at least one of an organic silicon surfactant and a phospholipid surfactant.

12. The method according to claim 9, characterized in that The tool is connected to a control device, and the control device is used to control the movement of the tool.

13. The method according to claim 9, characterized in that The cutter comprises a disc shear.

14. The method according to claim 13, characterized in that The circular shears adopt at least one of 60° double-edged edges, 60° single-edged edges and 30° single-edged edges.

15. The method according to claim 13 or 14, characterized in that include: Determine the zero point position of the circular shear using a standard sheet of known thickness; According to the thickness of the pole piece, adjusting the disc shear to the predetermined depth position; While the pole piece is unwinding, the pole piece is cut by using the circular shear; The cut pole piece is rolled up.

16. The method according to claim 15, characterized in that The pole piece unwinding tape speed is 20m / min to 120m / min.

17. A battery, characterized in that: The invention comprises the pole piece according to any one of claims 1 to 8, or the pole piece prepared by the method according to any one of claims 9 to 16.

18. An electrical equipment, characterized in that: Comprising the battery of claim 17.

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