Electrode plate, battery and preparation method of electrode plate

Abstract

The invention relates to the technical field of batteries, particularly provides an electrode plate, a battery and a preparation method of the electrode plate, and aims to solve the problem that the electrochemical performance of an existing battery is reduced due to increase of the thickness of the electrode plate. To this end, the electrode plate of the present application comprises: a current collector; and the active material layer is arranged on the current collector, and a channel is arranged on the active material layer. The channels are formed in the active material layer of the electrode plate, so that the tortuosity of the electrode plate can be reduced, the reaction kinetic performance of the electrode is improved on the premise that the thickness of the electrode plate is ensured to improve the energy density of the battery, and the electrochemical performance of the battery is further improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and specifically provides an electrode sheet, a battery, and a method for preparing the electrode sheet. Background Art

[0002] Alkali metal ion secondary batteries are widely used in power, energy storage, and digital 3C products due to their clean, efficient, light, and high capacity advantages. For portable electronic products and power equipment such as electric vehicles, batteries need to have higher energy density to meet the requirements of longer standby time or driving mileage. Therefore, the thick electrode design concept is applied to the production and processing of electrode sheets. That is, the thick electrode design method can greatly increase the active material load and reduce the ratio of inactive components, thereby increasing the battery energy density and reducing costs.

[0003] However, the increase in electrode thickness will lengthen the transport path of metal ions and increase battery impedance, thereby affecting the electrode reaction kinetics and causing a decrease in battery rate performance. Therefore, when the thickness of the electrode sheet increases to a certain extent, the material utilization rate decreases and the energy density of the battery cannot be fully utilized.

[0004] Accordingly, a new solution is needed in the art to solve the above problems. Summary of the invention

[0005] The present application aims to solve the above technical problem, that is, to solve the problem that the electrochemical performance of the existing alkali metal secondary battery decreases due to the increase in the thickness of the electrode sheet.

[0006] In a first aspect, the present application provides an electrode sheet, comprising:

[0007] current collector;

[0008] The active material layer is arranged on the current collector, and the active material layer is provided with grooves.

[0009] In the case of adopting the above-mentioned technical solution, the present application sets grooves on the active material layer. When the battery is powered on, when the metal ions in the electrode move under the action of the electric field, the metal ions in the pores near the grooves can move laterally and enter the grooves, and then directly pass through the active material layer along the grooves. In this way, each groove can guide the metal ions in the pores near it, and collect part of the metal ions in the pores near it into the grooves (the remaining metal ions can also continue to be transmitted between the pores), so that these part of the ions can directly pass through the electrode along the grooves, which can reduce the transmission path of the ions, thereby improving the electrode reaction kinetics.

[0010] In one technical solution of the above electrode sheet, the depth of the groove is less than the thickness of the active material layer.

[0011] When the above technical solution is adopted, the formation of other by-products due to the reaction between the electrolyte and the current collector can be avoided, thereby ensuring that the overall performance of the battery is not affected.

[0012] In one technical solution of the above electrode sheet, the depth d of the groove and the depth D of the active material layer satisfy the following relationship:

[0013] 0.3D≤d≤0.7D.

[0014] In one technical solution of the above electrode sheet, the total cross-sectional area of ​​the notches of all the grooves on the active material layer accounts for 40%-80% of the cross-sectional area of ​​the active material layer.

[0015] In a technical solution of the above electrode sheet, the cross-sectional area of ​​the groove at each position along the thickness direction of the active material layer is equal.

[0016] When the above technical solution is adopted, the structural properties of the battery, such as structural rigidity and flexibility, can be guaranteed to the maximum extent, while reducing the tortuosity of the electrode and improving the electrochemical performance of the battery.

[0017] In a technical solution of the above-mentioned electrode sheet, the groove includes a first groove extending along a first direction and a second groove extending along a second direction, and the first direction intersects with the second direction.

[0018] When the above technical solution is adopted, it is beneficial to the processing of the groove.

[0019] In a technical solution of the above electrode sheet, a plurality of the first grooves and / or the second grooves are arranged side by side.

[0020] In a technical solution of the above-mentioned electrode sheet, the angle between the first direction and the second direction is 40°-60°.

[0021] When the above technical solution is adopted, the tortuosity of the pole piece can be reduced to the maximum extent while ensuring the structural rigidity of the pole piece itself and the proportion of active materials, which is beneficial to improving the overall performance of the battery.

[0022] In a technical solution of the electrode sheet, the spacing between adjacent first grooves is 200-800 μm; and / or

[0023] The distance between adjacent second grooves is 200-800 μm.

[0024] When the above technical solution is adopted, the tortuosity of the pole piece can be reduced to the maximum extent while ensuring the structural rigidity of the pole piece itself and the proportion of active materials, which is beneficial to improving the overall performance of the battery.

[0025] In a second aspect, the present application provides a battery, comprising one or more battery cells, wherein the battery cells include the electrode sheet according to any one of the first aspect.

[0026] In a third aspect, the present application provides a method for preparing an electrode sheet, comprising:

[0027] Providing a rolled electrode sheet, wherein the electrode sheet comprises a current collector and an active material layer disposed on the current collector;

[0028] A groove is formed by etching the active material layer.

[0029] In the case of adopting the above technical solution, by adjusting the parameters of the laser processing equipment itself, it is beneficial to control the groove depth. At the same time, by adjusting the position of the laser etching die head or the active material layer, it can also meet the requirements of different groove morphologies. On the other hand, the process step of using laser etching to etch the groove to obtain a low-tortuosity thick pole piece is carried out after the initial processing of the pole piece is completed. The laser etching step will not impose any constraints on the upstream processing steps of the pole piece. The initial processing process of the pole piece and the laser etching process are two independent processes, which can maximize the avoidance of mutual constraints between the two process processes and ensure the forming yield of the electrode piece.

[0030] In a technical solution of the above preparation method, etching the active material layer to form a groove comprises:

[0031] When the electrode sheet is fixed, controlling the etching die head to feed along a first direction to form a plurality of first grooves arranged side by side;

[0032] The feeding direction of the etching die head is adjusted to control the etching die head to feed along a second direction to form a plurality of second grooves arranged side by side and intersecting the first grooves.

[0033] In a technical solution of the above preparation method, etching the active material layer to form a groove comprises:

[0034] When the electrode sheet is fixed, controlling the etching die head to feed along a first direction to form a plurality of first grooves arranged side by side;

[0035] The stage is rotated to a preset angle, and the etching die head is controlled to advance along the first direction to form a plurality of second grooves arranged side by side and intersecting the first grooves. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, in which:

[0037] Figure 1is a schematic longitudinal cross-sectional view of a thick electrode sheet in the prior art;

[0038] Figure 2 is a top view of an electrode sheet according to an embodiment of the present application;

[0039] Figure 3 is a schematic longitudinal cross-sectional view of an electrode sheet according to an embodiment of the present application;

[0040] Figure 4 is a top view of an electrode sheet according to another embodiment of the present application;

[0041] Figure 5 It is a flow chart of the main steps of a method for preparing an electrode sheet according to an embodiment of the present application.

[0042] In the figures, the reference numerals refer to the following:

[0043] 1. Current collector; 2. Active material layer; 21. Channel; 211. First channel; 212. Second channel. DETAILED DESCRIPTION

[0044] The preferred embodiments of the present application are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present application and are not used to limit the scope of protection of the present application. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0045] It should be noted that in the description of this application, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the drawings. This is only for the convenience of description, and does not indicate or imply that the relevant devices or components must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on this application. In addition, the ordinal numbers "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0046] In addition, it should be noted that in the description of this application, unless otherwise clearly specified and limited, the terms "installation" and "connection" 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 a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0047] For alkaline metal ion secondary batteries (such as lithium batteries), the electrode plates are porous structures. Therefore, the transmission process of metal ions in the electrode pores is related to the porosity, pore structure and wettability of the electrolyte. However, as the electrode thickness increases, the transmission path of metal ions in the electrode pores becomes an important influencing factor in the battery charging and discharging process.

[0048] Reference Figure 1 , is a schematic diagram of the longitudinal cross-section of a thick electrode sheet in the prior art. The direction of the arrow indicated by the dotted line in the figure is the transmission direction of ions. In the figure, Δx is the thickness of the electrode sheet, and ΔL is the length of the dotted line, i.e., the actual transmission path of the metal ions. First of all, a concept needs to be mentioned - tortuosity. The tortuosity represents the degree of tortuosity of the transmission path of metal ions in the porous electrode sheet. The tortuosity can be expressed by the value of ΔL / Δx. It can be seen that the larger the value of ΔL / Δx, the greater the tortuosity of the electrode sheet, and the worse the battery rate performance and electrode reaction kinetics. By Figure 1 It can be seen that, under the premise of a certain electrode thickness Δx, the larger ΔL is, the higher the tortuosity of the electrode sheet is. Therefore, under the premise of meeting the design requirements of thick electrode sheets, reducing the tortuosity of the electrode sheet is helpful to improve the electrochemical kinetic performance of the battery.

[0049] The present application first discloses an electrode sheet, referring to Figure 2 , is a top view (planar schematic diagram) of an electrode sheet according to an embodiment of the present application, Figure 3 : is a longitudinal cross-sectional schematic diagram of an electrode sheet according to an embodiment of the present application. The electrode sheet includes a current collector 1 and an active material layer 2, the current collector refers to a metal foil, such as copper foil, aluminum foil and the like, the active material layer 2 is arranged on the surface of the current collector 1, and the active material layer 2 is formed on the active material layer 2 by coating, rolling and the like, which is a well-known technology in the art and will not be described in detail in the present application.

[0050] Reference Figure 2 and Figure 3 , channels 21 for ion transport are provided on the active material layer 2. In one embodiment of the present application, the channels 21 include a plurality of first channels 211 extending along a first direction and a plurality of second channels 212 extending along a second direction, wherein the plurality of first channels 211 are arranged side by side, and the plurality of second channels 212 are arranged side by side.

[0051] It should be noted that the plane formed by the first direction and the second direction is perpendicular to the thickness direction of the electrode sheet, and the first direction intersects with the second direction, so that the first groove 211 and the second groove 212 intersect with each other.

[0052] Reference Figure 3, the direction indicated by the arrow in the figure is the transmission direction of the metal ions. It can be seen that the present application sets the groove 21 on the active material layer 2. When the battery is powered on, the metal ions in the electrode move under the action of the electric field. The metal ions in the pores near the groove 21 can move laterally and enter the groove 21, and then directly pass through the active material layer 2 along the groove 21. In this way, each groove 21 can guide the metal ions in the pores near it, and collect part of the metal ions in the pores near it into the groove 21 (the remaining metal ions can also continue to be transmitted between the pores), so that the part of the ions can directly pass through the electrode along the groove, thereby reducing the transmission path of the ions and improving the electrode reaction kinetics.

[0053] It can be seen that the present application can reduce the tortuosity of the electrode sheet by providing the groove 21 on the active material layer 2 of the electrode sheet, thereby improving the electrode reaction kinetics while ensuring the thickness of the electrode sheet to increase the battery energy density, thereby improving the electrochemical performance of the battery.

[0054] Reference Figure 3 In some embodiments of the present application, the depth of the groove 21 is less than the thickness of the active material layer 2 .

[0055] It should be noted that, although theoretically, the closer the depth of the groove 21 is to the thickness of the active material layer 2, the lower the tortuosity of the pole piece, and the more conducive to ion transmission, but based on actual production and processing considerations, when the groove 21 penetrates the entire active material layer 2 to expose the current collector 1, the electrolyte will react with the current collector 1, thereby reducing the overall performance of the battery. Therefore, setting the depth of the groove 21 to be less than the thickness of the active material layer 2 can avoid the formation of other byproducts due to the reaction of the electrolyte with the current collector 1, thereby ensuring that the overall performance of the battery is not affected.

[0056] On the other hand, when the depth of the groove 21 is too large, not only the rigidity and flexibility of the electrode sheet will be reduced, but also the bonding strength between the active material layer 2 and the current collector 1 will be reduced, so that the active material layer 2 may fall off from the surface of the current collector 1.

[0057] In some embodiments of the present application, the depth d of the groove 21 and the thickness D of the active material layer 2 satisfy the following relationship:

[0058] 0.3D≤d≤0.7D.

[0059] It should be noted that if the depth of the groove 21 is too small, the tortuosity of the pole piece will not decrease significantly, affecting the electrode reaction kinetics and the electrolyte infiltration effect. Therefore, controlling the depth of the groove 21 within the above range can maximize the structural rigidity, flexibility and other structural properties of the battery, while reducing the tortuosity of the pole piece and improving the electrochemical performance of the battery.

[0060] In some embodiments of the present application, the thickness of the pole piece is 140-230 μm, so that in the case of a "thick pole piece", the tortuosity of the "thick pole piece" is reduced by setting the groove 21 of the present application, thereby improving the electrochemical performance of the battery. Of course, the above-mentioned thickness value of the pole piece is only an optional method of the present application, and it does not constitute a limitation to the present application, that is, the present application is applicable to pole pieces of any thickness.

[0061] In some embodiments of the present application, the total cross-sectional area of ​​the notches of all the grooves 21 on the active material layer 2 accounts for 40%-80% of the cross-sectional area of ​​the active material layer 2. It should be noted that in the above statement, "cross-sectional area" refers to the area of ​​the cross section perpendicular to the thickness direction of the active material layer 2. In addition, in the embodiments of the present application, the cross-sectional area of ​​each groove 21 at each position in the thickness direction of the active material layer is the same (that is, the groove 21 is of equal width in the ion transport direction), and the total cross-sectional area of ​​the notches of each groove 21 refers to the sum of the areas of the cross sections of each groove 21 at its notch along the cross section perpendicular to the thickness direction of the active material layer 2 (the "notch" described in the present application refers to the end of the groove 21 away from the current collector 1, and accordingly, the position corresponding to the notch is the "bottom of the groove". In the embodiments of the present application, the cross-sectional area of ​​the groove 21 at its notch and the bottom of the groove is the same). The cross-sectional area of ​​the groove 21 is controlled within the above range in order to take into account both the structural strength of the electrode sheet itself and the total width of the ion transport channel, so that the electrode sheet can maximize the electrochemical performance of the battery while ensuring its own structural strength.

[0062] Although in the embodiments of the present application, the grooves 21 are set to be of equal width (the cross-sectional areas of each groove 21 at each position in the thickness direction of the active material layer 2 are equal, and the cross-sectional areas of different grooves 21 are also equal) are used for illustrative description, this does not constitute a limitation to the present application. In some other implementations, based on factors such as the difficulty of processing, each groove 21 may also be of non-equal width. For example, the width of the groove 21 near the groove mouth is wider, and the width near the groove bottom is narrower, etc., and different grooves 21 may also be set to have different widths from each other.

[0063] Reference Figure 2 and Figure 4 , Figure 4 2 is a top view of an electrode sheet according to another embodiment of the present application. As can be seen from the figure, in order to verify the influence of different morphological conditions of the groove 21 on the electrochemical performance of the battery, the inventors Figure 2 The extending directions of the first groove 211 and the second groove 212 are perpendicular to each other (ie, the first direction is perpendicular to the second direction), and Figure 4Tests were conducted for the case where the angle between the extension directions of the first groove 211 and the second groove 212 was 60° (i.e., the angle between the first direction and the second direction was 60°), and compared with a conventional pole piece without the groove 21, as shown in Table 1 below. 20mA / g 50mA / g 100mA / g 200mA / g 500mA / g 1 186.5mAh / g 161.9mAh / g 128.8mAh / g 98.7mAh / g 70.3mAh / g 2 230.5mAh / g 184.7mAh / g 144.5mAh / g 110.5mAh / g 95.5mAh / g 3 236.5mAh / g 193.5mAh / g 153.4mAh / g 125.1mAh / g 105.6mAh / g Table 1

[0064] In the above Table 1, No. 1 is a conventional electrode without grooves etched on the active material layer 2, No. 2 is a electrode when the extension directions of the first groove 211 and the second groove 212 etched on the active material layer 2 are perpendicular to each other, and No. 3 is a electrode when the extension directions of the first groove 211 and the second groove 212 etched on the active material layer 2 are at an angle of 90° (it should be noted that the above Table 1 is based on test data obtained from the same batch of electrode sheets at the same thickness). The first row of data variables in Table 1 represents current density (the current value passing through per unit mass of active material), and the values ​​corresponding to Nos. 1, 2, and 3 are battery capacities, that is, the capacity exerted when the unit mass of active material passes through the above current value, which characterizes the rate performance of the battery.

[0065] Specifically, the thickness of the active material layer of the pole pieces numbered 1-3 in Table 1 is 183 μm, the depth of the grooves of the pole pieces numbered 2 and 3 is 110 μm, the spacing between adjacent first grooves 211 of the pole pieces numbered 2 and 3 is 3 μm, the spacing between adjacent second grooves 212 is 3 μm, and the ratio of the total cross-sectional area of ​​all grooves in numbers 2 and 3 to the cross-sectional area of ​​the active material layer is 0.6.

[0066] Therefore, it can be seen from Table 1 that the rate performance of the electrode piece with grooves etched on it is significantly improved compared to the electrode piece without grooves etched on it. At the same time, it can be found that in the case of etching grooves, when the angle between the extension directions of the first groove 211 and the second groove 212 is 60°, the rate performance of the battery is greater than the rate performance when the angle between the extension directions of the first groove 211 and the second groove 212 is 90°. This is because, when the angle between the extension directions of the first groove 211 and the second groove 212 is 90°, from the top view of the pole piece, the first groove 211 and the second groove 212 form a plurality of rectangular units, and when the angle between the extension directions of the first groove 211 and the second groove 212 is 60°, from the top view of the pole piece, the first groove 211 and the second groove 212 form a plurality of rhombus units, and from a geometric point of view, the perimeter of the rhombus pattern per unit area is greater than the perimeter of the rectangular unit, and And the more "slender" the diamond pattern is, the larger its circumference is. For a pole piece per unit area, the larger the circumference of the pattern formed by the first groove 211 and the second groove 212 is, the larger the volume ratio of the active material layer 2 occupied by the first groove 211 and the second groove 212 in the spatial dimension is. In this way, the wettability of the electrolyte is better, and more ions can pass through the first groove 211 and the second groove 212. That is, the lower the tortuosity of the pole piece, the higher the rate performance of the battery will naturally be.

[0067] Of course, the angle between the extension direction of the first groove 211 and the second groove 212 cannot be too small. When the angle is too small, the removal amount of the active material layer 2 on the pole piece will be too large, which will not only lead to a decrease in the proportion of active materials, but also affect the structural rigidity of the pole piece. Therefore, in one embodiment of the present application, the angle between the extension direction of the first groove 211 and the second groove 212 is set to 40°-60° (that is, the angle between the first direction and the second direction is 40°-60°). By setting the angle between the extension direction of the first groove 211 and the second groove 212 within the above range, the tortuosity of the pole piece can be minimized on the basis of ensuring the structural rigidity of the pole piece itself and the proportion of active materials, which is beneficial to the improvement of the overall performance of the battery.

[0068] It should also be noted that, although in the above-mentioned embodiments of the present application, the structure of the groove 21 is described as straight grooves intersecting each other, it does not constitute a limitation to the present application. For example, in some other implementations, the groove 21 can also be a plurality of annular grooves arranged radially outward along the geometric center of the pole piece, or the groove 21 can also be a plurality of independent blind holes arranged on the active material layer 2, and the plurality of blind holes are arranged in an array on the active material layer 2, and so on.

[0069] The above is the influence of the arrangement direction of the first groove 211 and the second groove 212 on the pole piece rate performance. The following Table 2 is an experiment conducted on different pole pieces based on another influencing factor, that is, the groove spacing. 20mA / g 50mA / g 100mA / g 200mA / g 500mA / g 1 181.1mAh / g 161.5mAh / g 123.9mAh / g 93.8mAh / g 67.3mAh / g 2 225.2mAh / g 180.2mAh / g 139.7mAh / g 105.1mAh / g 88.6mAh / g 3 231.2mAh / g 188.7mAh / g 153.6mAh / g 120.4mAh / g 103.4mAh / g Table 2

[0070] In the above Table 2, No. 1 is the pole piece when the groove spacing is 102μm, No. 2 is the pole piece when the groove spacing is 203μm, and No. 3 is the pole piece when the groove spacing is 405μm (it should be noted that the above Table 2 is based on the test data obtained from the same batch of pole pieces at the same thickness, and the above "groove spacing" refers to the interval between adjacent first grooves 211 and the interval between adjacent second grooves 212. In the above test of the present application, the interval between adjacent first grooves 211 and the interval between adjacent second grooves 212 are equal). Similarly, the first row of data variables in Table 2 represents the current density (the current value passing through per unit mass of active material), and the values ​​corresponding to No. 1, 2, and 3 are the battery capacity, that is, the capacity exerted when the unit mass of active material passes through the above current value, which characterizes the rate performance of the battery.

[0071] Specifically, the thickness of the active material layer of the pole pieces numbered 1-3 in Table 2 is 183 μm, the depth of the grooves of the pole pieces numbered 2 and 3 is 110 μm, and the ratio of the total cross-sectional area of ​​all grooves in numbers 2 and 3 to the cross-sectional area of ​​the active material layer is 0.6 and 0.5, respectively.

[0072] It can be seen from Table 2 that when the grooves are etched on the pole piece, the larger the groove spacing, the smaller the rate performance of the battery. This is because, from a geometric perspective, when the groove spacing is smaller, the volume ratio of the active material layer 2 in the unit volume of the active material layer 2 in the spatial dimension is larger, so the wettability of the electrolyte is better. From the top view of the pole piece, the larger the ratio of the groove to the area of ​​the pole piece per unit area, the more conducive it is for ions to move to the grooves near it, and the lower the tortuosity of the pole piece, the higher the rate performance of the battery.

[0073] Similarly, when the slot spacing is too small, the amount of active material layer 2 removed from the pole piece will be too large, which will not only lead to a decrease in the proportion of active materials, but also affect the structural rigidity of the pole piece. Therefore, in one embodiment of the present application, the spacing between adjacent first slots 211 and the spacing between adjacent second slots 212 are both 200-800μm. By controlling the slot spacing within the above range, the tortuosity of the pole piece can be minimized while ensuring the structural rigidity of the pole piece itself and the proportion of active materials, which is beneficial to the improvement of the overall performance of the battery.

[0074] The present application also discloses a battery, which includes one or more battery cells, wherein each battery cell is composed of the electrode sheet in any of the above embodiments.

[0075] The present application also discloses a method for preparing an electrode sheet, which uses laser etching to form the groove 21 in the above embodiment on the active material layer 2 of the electrode sheet.

[0076] Specifically, refer to Figure 5 , is a flow chart of the main steps of a method for preparing an electrode sheet according to an embodiment of the present application, which includes:

[0077] S101: placing the rolled electrode sheet on a stage.

[0078] The electrode sheet in step S101 has been subjected to coating, rolling and other process steps, that is, the active material layer has been formed on the current collector. In one embodiment of the present application, a laser processing device is used to etch the electrode sheet to form a groove, so the stage can be a stage integrated on the laser processing device or a stage independent of the laser processing device, and the present application does not limit this.

[0079] S102: Etching to form grooves on the active material layer.

[0080] Before step S102 is performed, the operating parameters of the laser processing equipment should be adjusted. For example, in one embodiment of the present application, the laser welding power is set to 20W, the etching pressure is set to 30 pounds per square inch, and the laser die feed speed is set to 20mm / s. The above parameters are several important parameters that affect the etching effect of the pole piece. The laser welding power and etching pressure directly affect the final etching depth of the groove, while the laser die feed speed will affect the quality of the pole piece etching. For example, when the laser die feed speed is too fast, it will affect the flatness of the inner wall of the groove formed by etching, and even "powdering" will occur, causing the active material layer 2 to be partially broken.

[0081] In one embodiment of the present application, during the specific processing, step S102 includes:

[0082] S1021: Fix the loading platform.

[0083] S1022: With the stage and the electrode sheet fixed, control the etching die head to advance along a first direction to form a plurality of first grooves arranged side by side.

[0084] S1023: adjusting the feeding direction of the etching die head, and controlling the etching die head to feed along the second direction to form a plurality of second grooves arranged side by side and intersecting the first grooves.

[0085] Since the first groove and the second groove intersect with each other, it is necessary to divide the etching into two steps. As described in this embodiment, first, through step S1022, a plurality of first grooves arranged side by side are formed on the active material layer, and then the stage is kept stationary, and the feeding direction of the etching die is adjusted through S1023, so that the etching die is fed along a second direction intersecting with the first direction, thereby forming a plurality of second grooves intersecting with the first grooves.

[0086] In another embodiment of the present application, step S102 includes:

[0087] S1021: Fix the loading platform.

[0088] S1022: With the stage and the electrode sheet fixed, control the etching die head to advance along a first direction to form a plurality of first grooves arranged side by side.

[0089] S1024: Rotate the stage to a preset angle, and control the etching die head to feed along the first direction to form a plurality of second grooves arranged side by side and intersecting the first grooves.

[0090] It can be seen that, unlike the aforementioned embodiment, after step S1022, in order to form a second groove on the active material layer, the etching die is kept stationary and the stage is rotated to adjust the relative position relationship between the active material layer and the etching die, so that after the etching die continues to feed along the first direction, a second groove intersecting with the first groove can be formed on the active material layer.

[0091] It should also be noted that the above preset angle can be determined according to actual needs, and this application does not limit it. For example, when the angle between the first groove extension direction and the second groove extension direction is 50° after the electrode sheet is processed and formed, the preset angle is 50°.

[0092] As mentioned above, the present application uses laser etching to form grooves on the active material layer of the electrode sheet. By adjusting the parameters of the laser processing equipment itself, it is beneficial to control the depth of the grooves. At the same time, by adjusting the position of the laser etching die or the active material layer, it can also meet the requirements of different groove morphologies. On the other hand, the process step of using laser etching to etch the grooves to obtain a low-tortuosity thick electrode sheet is carried out after the initial processing of the electrode sheet is completed, that is, the laser etching step will not impose any constraints on the upstream processing steps of the electrode sheet. The initial processing process of the electrode sheet and the laser etching process are two independent processes, which can maximize the avoidance of mutual constraints between the two process processes and ensure the forming yield of the electrode sheet.

[0093] So far, the technical solutions of the present application have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present application.

Claims

1. An electrode sheet, characterized in that: include: current collector; The active material layer is arranged on the current collector, and the active material layer is provided with grooves.

2. The electrode sheet according to claim 1, characterized in that: The depth of the channel is smaller than the thickness of the active material layer.

3. The electrode sheet according to claim 2, characterized in that: The depth d of the groove and the depth D of the active material layer satisfy the following relationship: 0.3D≤d≤0.7D.

4. The electrode sheet according to claim 2, characterized in that: The total cross-sectional area of ​​the grooves of all the grooves on the active material layer accounts for 40%-80% of the cross-sectional area of ​​the active material layer.

5. The electrode sheet according to claim 4, characterized in that: The cross-sectional areas of the channels at various locations along the thickness direction of the active material layer are equal.

6. The electrode sheet according to claim 1, characterized in that: The channel includes a first channel extending along a first direction and a second channel extending along a second direction, the first direction intersecting the second direction.

7. The electrode sheet according to claim 6, characterized in that: A plurality of the first channels and / or the second channels are arranged side by side.

8. The electrode sheet according to claim 6, characterized in that: The included angle between the first direction and the second direction is 40°-60°.

9. The electrode sheet according to claim 6, characterized in that: The spacing between adjacent first grooves is 200-800 μm; and / or The distance between adjacent second grooves is 200-800 μm.

10. A battery, characterized in that: The invention comprises one or more battery cells, wherein the battery cells comprise the electrode sheet according to any one of claims 1 to 9.

11. A method for preparing an electrode sheet, characterized in that: include: Providing a rolled electrode sheet, wherein the electrode sheet comprises a current collector and an active material layer disposed on the current collector; A groove is formed by etching the active material layer.

12. The preparation method according to claim 11, characterized in that: The etching to form a groove on the active material layer comprises: When the electrode sheet is fixed, controlling the etching die head to feed along a first direction to form a plurality of first grooves arranged side by side; Adjusting the feeding direction of the etching die head to control the etching die head to feed along a second direction to form a plurality of second grooves arranged side by side and intersecting the first grooves; or When the electrode sheet is fixed, controlling the etching die head to feed along a first direction to form a plurality of first grooves arranged side by side; The electrode sheet is rotated at a preset angle, and the etching die head is controlled to feed along the first direction to form a plurality of second grooves arranged side by side and intersecting the first grooves.

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