Electrode sheet, method for manufacturing electrode sheet, secondary battery, and electronic device

Abstract

The application provides an electrode sheet, a manufacturing method of the electrode sheet, a secondary battery and an electronic device. The electrode sheet comprises a current collector and an active material layer, and the active material layer is arranged on the surface of the current collector. In the direction parallel to the surface of the current collector, the active material layer comprises a plurality of active material film pieces, and a spacing is arranged between any adjacent active material film pieces to form a through hole, and in the direction perpendicular to the surface of the current collector, the through hole penetrates the active material layer. In the direction parallel to the surface of the current collector, the thickness of each layer of the active material film piece is 70-160 μm, and the width of the through hole is 5-20 μm. In the direction perpendicular to the surface of the current collector, the height of each layer of the active material film piece is 140-500 μm. By arranging the active material layer with the plurality of active material film pieces, the through hole of the active material layer is formed in the active material layer, and ions can be quickly transmitted in the through hole, so that the kinetic performance of the thick electrode sheet is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to an electrode sheet, a manufacturing method of the electrode sheet, a secondary battery and an electronic device. BACKGROUND

[0002] The secondary battery has advantages of large energy density, high power and long cycle life, and is widely used in the field of consumer electronics. With the continuous expansion of its application range, especially in electric bicycles and electric vehicles, the requirement for the energy density of lithium ion batteries is continuously increasing. In order to improve the energy density of the secondary battery, the thickness of the electrode sheet is gradually increased. However, in the thick electrode sheet, the ion transmission path is long, which leads to poor kinetic performance of the thick electrode sheet. How to improve the kinetic performance of the thick electrode sheet has become a technical problem to be solved urgently. SUMMARY

[0003] The present application provides an electrode sheet, a manufacturing method of the electrode sheet, a secondary battery and an electronic device to solve the above technical problems.

[0004] Embodiments of the present application are implemented as follows:

[0005] An electrode sheet includes a current collector and an active material layer, and the active material layer is arranged on the surface of the current collector. Along the direction parallel to the surface of the current collector, the active material layer includes a plurality of active material film pieces, and a spacing is arranged between any adjacent active material film pieces to form a through hole, and along the direction perpendicular to the surface of the current collector, the through hole penetrates the active material layer. Along the direction parallel to the surface of the current collector, the thickness of each active material film piece is 70-160 μm, and the width of the through hole is 5-20 μm. Along the direction perpendicular to the surface of the current collector, the height of each active material film piece is 140-500 μm.

[0006] In this way, by arranging the active material layer with a plurality of active material film pieces, the through hole of the active material layer is formed in the active material layer, and the ion can be quickly transmitted in the through hole, thereby improving the kinetic performance of the thick electrode sheet.

[0007] In one embodiment of the present application, the height of the active material film piece is 200-400 μm. Further, the height of the active material film piece is 200-300 μm. By restricting the height h of the active material film piece within a certain range, the kinetic performance and energy density of the electrode sheet can be effectively improved, and the manufacturing cost can be controlled within a reasonable range, meeting various needs of production and use.

[0008] In one embodiment of the present application, the width of the through hole is greater than 5 μm and less than 10 μm. By restricting the width a of the through hole within a certain range, the wettability of the electrolyte can be improved, and the kinetic performance of the electrode sheet can be improved while the energy density is taken into account.

[0009] In one embodiment of the present application, the ratio of the height of the active material film to the width of the through hole is 7.5-100. Further, the ratio of the thickness of the active material film to the width of the through hole is 17-50. In the case of ensuring that the proportion of active material in the electrode sheet is relatively high, the ion can be quickly transported in the active material layer.

[0010] In one embodiment of the present application, the difference in porosity at the surface layer and the bottom layer of the active material film is less than 3%. That is, the active material particles in the active material film are uniformly distributed, and the porosity of the film is basically consistent. In the active material layer formed by winding the thin film-like active material film, the active material is more uniformly distributed, the porosity difference of the active material layer is small, and the problem of large porosity in some areas and small porosity in some areas does not occur, so that the ion can be uniformly and quickly transported in the electrode sheet, further improving the kinetic performance of the electrode sheet.

[0011] In one embodiment of the present application, the active material layer includes a binder, and the binder is fibrous, so that the active material particles can be uniformly distributed, and the flexibility of the active material film is increased.

[0012] In one embodiment of the present application, the electrode sheet can be bent, and the bending radius of curvature of the electrode sheet is greater than 1.5 mm.

[0013] The embodiments of the present application also provide a manufacturing method of an electrode sheet, for manufacturing the electrode sheet described in the above embodiments, and the manufacturing method of the electrode sheet includes:

[0014] Mixing the active material particles and the fibrous binder to prepare an active material support film;

[0015] Winding or stacking or layer-by-layer winding the active material support film to form an active material column, and slicing the active material column to obtain an active material layer with multiple layers of active material films, and a through hole is formed between the adjacent two layers of active material films;

[0016] Compositing the active material layer on the surface of the current collector.

[0017] The embodiments of the present application also provide a secondary battery including a packaging body and the electrode sheet described in the above embodiments, and the electrode sheet is arranged in the packaging body.

[0018] The embodiments of the present application also provide an electronic device including a power consuming element and the secondary battery described in the above embodiments, and the power consuming element is electrically connected to the secondary battery. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be considered as limiting the scope. Other related drawings can also be obtained by those of ordinary skill in the art without creative effort based on these drawings.

[0020] Figure 1 A structure schematic diagram of an electrode sheet according to an embodiment of the present application.

[0021] Figure 2 A structure schematic diagram of an electrode sheet according to an embodiment of the present application. Figure 1 A cross-sectional structure schematic diagram of the electrode sheet shown in II-II, the cross-sectional direction of II-II is the radial direction of the circular electrode sheet shown in FIG. 1. Figure 2 A cross-sectional structure schematic diagram of the electrode sheet shown in II-II, the cross-sectional direction of II-II is the radial direction of the circular electrode sheet shown in FIG. 1.

[0022] Figure 3 A structure schematic diagram of the electrode sheet after bending.

[0023] Figure 4 A structure schematic diagram of the electrode sheet after bending.

[0024] Figure 5 A structure schematic diagram of an electrode sheet according to an embodiment of the present application.

[0025] Figure 6 A structure schematic diagram of an electrode sheet according to an embodiment of the present application.

[0026] Figure 7 A structure schematic diagram of an electrode sheet according to an embodiment of the present application.

[0027] Figure 8 A structure schematic diagram of a secondary battery according to an embodiment of the present application.

[0028] Figure 9 A structure schematic diagram of an electronic device according to an embodiment of the present application.

[0029] Main element symbol explanation:

[0030] Electrode sheet 100

[0031] Current collector 10

[0032] Active material layer 20

[0033] Active material membrane 21

[0034] Active material column 22

[0035] Through hole 30

[0036] Secondary battery 200

[0037] Packaging body 201

[0038] Diaphragm 202

[0039] Electronic device 300

[0040] Power consuming element 301 DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application.

[0042] It should be noted that when an element is referred to as being "fixed" to another element, it can be directly on the other element or there can be intervening elements. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or there can be intervening elements. When an element is referred to as being "disposed on" another element, it can be directly on the other element or there can be intervening elements. The terms "vertical", "horizontal", "left", "right", and similar expressions used herein are for illustrative purposes only.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0044] Some embodiments of the present application are described in detail. The following embodiments and features of the embodiments can be combined with each other in the case of no conflict.

[0045] Referring to Figure 1 The present embodiment provides an electrode sheet 100 including a current collector 10 and an active material layer 20. The active material layer 20 is provided on a surface of the current collector 10. In a direction parallel to the surface of the current collector 10, the active material layer 20 includes a plurality of active material films 21, and a gap is provided between any adjacent active material films 21 to form a through hole 30, which penetrates the active material layer 20 in a direction perpendicular to the surface of the current collector 10. In the direction parallel to the surface of the current collector 10, a thickness b of each active material film 21 is 70 μm to 160 μm, and a width a of the through hole 30 is 5 μm to 20 μm. In the direction perpendicular to the surface of the current collector 10, a height h of each active material film 21 is 140 μm to 500 μm.

[0046] The application forms a through hole 30 in the active material layer 20 by setting the active material layer 20 with a plurality of active material film pieces 21, so that ions can be quickly transmitted in the through hole 30, thereby improving the kinetic performance of the thick electrode sheet. By limiting the thickness of the active material film piece 21, the width of the through hole 30 and the height of the active material film piece 21, the ions can be quickly transmitted in the active material layer 20 and the energy density of the electrode sheet 100 can be maximized, thereby improving the electrical performance of the electrode sheet 100.

[0047] The purpose of winding the active material film piece 21 and slicing the wound film piece to form an active material layer 20 with a certain thickness is to improve the kinetic performance of the electrode sheet 100. As shown in Figure 2 The height h of the active material film piece 21 is the thickness of the active material layer 20. When the thickness of the active material layer 20 exceeds 500 μm, the energy density of the electrode sheet 100 grows at a slower rate, and the manufacturing difficulty increases. In one embodiment of the application, the height h of the active material film piece 21 is 200-400 μm. The height h of the active material film piece 21 can be 200 μm, 210 μm, 220 μm, 230 μm, 240 μm, 250 μm, 260 μm, 270 μm, 280 μm, 290 μm, 300 μm, 310 μm, 320 μm, 330 μm, 340 μm, 350 μm, 360 μm, 370 μm, 380 μm, 390 μm, 400 μm, or any range formed by any two of these values. Preferably, the height h of the active material film piece 21 is 200-300 μm. By restricting the height h of the active material film piece 21 within a certain range, the kinetic performance and energy density of the electrode sheet 100 can be effectively improved, and the manufacturing cost can be controlled within a reasonable range to meet various production and use requirements. Figure 2 As shown in Figure 1 The cross-sectional structure of the electrode sheet at II-II is shown in Figure 2 The radial direction of the circular electrode sheet is also the normal direction of the surface of the current collector 10.

[0048] In the embodiment of the application, the cross section of the active material film piece 21 is photographed by an electron microscope, and the thickness b of the active material film piece 21 is measured by using the photographing result. The height h of the active material film piece 21 can be directly measured by using a high-precision measuring device such as a micrometer. The measurement result of the thickness b or the height h of the active material film piece 21 is the average value of three measurement results, so as to reduce the measurement error.

[0049] Further, in the active material layer 20, the size of the pores between the active material particles is generally less than 5 μm. If the width a of the through hole 30 is less than 5 μm, the ion transmission will be affected due to the too narrow through hole 30. If the width a of the through hole 30 is too large, for example, more than 40 μm, the energy density of the electrode sheet 100 will be reduced, which cannot meet the requirement of the energy density of the secondary battery. In one embodiment of the present application, the width a of the through hole 30 is limited to be greater than 5 μm and less than 10 μm. By limiting the width a of the through hole 30 to a certain range, the wettability of the electrolyte can be improved, so as to achieve the purpose of improving the kinetic performance and the energy density of the electrode sheet 100 at the same time.

[0050] In the embodiment of the present application, the width a of the through hole 30 can be in a range defined by any two of the following values: 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm.

[0051] The ratio h / a of the height h of the active material film 21 to the width a of the through hole 30 is the depth-diameter ratio of the through hole 30, which is a parameter that comprehensively reflects the energy density gain and the ion transmission capability. A larger value of h / a indicates that the through hole 30 is slender, and the total volume of the electrode sheet 100 is small, so that the active material accounts for a high proportion in the electrode sheet 100, and the energy density is larger. In one embodiment of the present application, the depth-diameter ratio of the through hole 30, i.e., the ratio of the thickness h of the active material film 21 to the width a of the through hole 30, is 7.5-100, and the depth-diameter ratio of the through hole 30 can be any two of the following values: 7.5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100. Preferably, the ratio of the thickness h of the active material film 21 to the width a of the through hole 30 is 17-50, which can make the active material account for a high proportion in the electrode sheet 100, and also enable the ions to be quickly transmitted in the active material layer 20.

[0052] Further, in the embodiment of the present application, the difference in the porosity of the active material film 21 at different height positions in the direction perpendicular to the surface of the current collector 10 is less than 3%, i.e., the active material particles in the active material film 21 are uniformly distributed, and the porosity of the film at different positions is basically consistent. Compared with the thick electrode sheet formed by one-time pressing, in the active material layer 20 formed by winding the thin film-shaped active material film 21, the active material is more uniformly distributed, the porosity difference of the active material layer 20 at different positions is small, and the problem that the porosity is large in some areas and small in some areas does not occur, so that the ions can be uniformly and quickly transmitted in the electrode sheet 100, and the kinetic performance of the electrode sheet 100 is further improved.

[0053] In an embodiment of the present application, the active material layer 20 further comprises a binder, and the binder is in a fibrous form. The fibrous binder can form a three-dimensional network structure, and the active material particles can be uniformly distributed in the three-dimensional network structure and uniformly distributed in the pores of the active material layer 20. The addition of the fibrous binder in the active material layer 20 can also make the active material layer 20 flexible, and the active material layer 20 is not easy to break when the electrode sheet 100 is bent, thereby improving the plasticity and versatility of the electrode sheet 100. As shown in Figure 3 The electrode sheet 100 can be bent, and the bending radius R of the electrode sheet 100 is greater than 1.5 mm.

[0054] The flexibility test of the electrode sheet 100 is as follows: the electrode sheet 100 is bent into a semicircle, and the radius R of the semicircle is measured. When R>1.5 mm, the electrode sheet does not fall off.

[0055] Please refer to Figure 4 The embodiment of the present application also provides a manufacturing method of the electrode sheet 100, which is used to manufacture the electrode sheet 100 described in the above embodiments. The manufacturing method of the electrode sheet 100 comprises the following steps: mixing the active material particles and the fibrous binder to prepare an active material support film; winding or stacking or layer-by-layer winding the active material support film to form an active material column 22, and slicing the active material column 22 to obtain an active material layer 20 having a plurality of active material film pieces 21, and forming a through hole 30 between the adjacent two active material film pieces 21; and combining the active material layer 20 with the surface of the current collector 10 to obtain the electrode sheet 100.

[0056] In Figure 4 In the embodiment shown in the figure, the active material support film can be an active material film piece 21 with a large size, and the active material column 22 is formed by winding. The active material column 22 is cut according to a predetermined size to obtain an active material layer 20 with a certain thickness. In the active material layer 20, the through hole 30 and the active material film piece 21 are distributed in a spiral shape, including but not limited to a spiral circle, a spiral rectangle or a spiral polygon, etc. The combination of the active material layer 20 and the current collector 10 includes but is not limited to the following: the active material layer 20 is adhered to the surface of the current collector 10 by setting a conductive adhesive between the active material layer 20 and the current collector 10; or a conductive coating is pre-set on the surface of the current collector 10, and the active material layer 20 is combined on the surface of the current collector 10 by curing the conductive coating.

[0057] In Figure 5 and Figure 6In the shown embodiment, the active material support film can include a plurality of large-size active material film pieces 21, and the active material column 22 is formed by nesting the plurality of active material film pieces 21 layer by layer, so that the through holes 30 in the active material layer 20 are a plurality of concentrically arranged annular holes. The shape of the annular hole includes but is not limited to a circle, a rectangle, a triangle, a polygon, etc., which is not limited in the present application.

[0058] In Figure 7 In the shown embodiment, the active material support film can be a whole piece of large-size active material film piece 21, or a plurality of large-size active material film pieces 21, which are stacked layer by layer or in a zigzag manner to form an active material column 22 or an active material block, and then the slice is compounded on the surface of the current collector 10 to obtain the electrode sheet 100. At this time, the through holes 30 in the active material layer 20 are approximately arrayed strip-shaped holes.

[0059] As Figure 8 As shown, the embodiments of the present application also provide a secondary battery 200, which includes a packaging body 201 and the above-mentioned electrode sheet 100, and the electrode sheet 100 is arranged in the packaging body 201. Specifically, the positive electrode sheet 100 and the negative electrode sheet 100 are arranged in the packaging body 201 in a stacked manner, and a separator 202 is arranged between the positive and negative electrode sheets 100 to prevent internal short circuit problems. The secondary battery 200 also includes connection terminals (not shown in the figure) respectively connected to the positive and negative electrode sheets 100, for electrically connecting an external circuit. The secondary battery 200 includes but is not limited to a battery, a battery device, etc.

[0060] Some specific examples and comparative examples are listed below to better illustrate the present application, in which lithium ion batteries are taken as examples.

[0061] Example One:

[0062] The preparation process of the electrode sheet 100 is as follows:

[0063] Preparation of the positive electrode sheet 100:

[0064] The positive active material lithium cobaltate (4.5V material, specific capacity 180mAh / g), the conductive agent, and the binder polytetrafluoroethylene (PTFE) are mixed in a weight ratio of 97.6:1.1:1.3, and then subjected to a fiberization process, a film extrusion process, and a cold pressing process to form a positive self-supporting film piece, and the film piece has a thickness b=70μm. The self-supporting film piece is wound into a cylindrical body with a diameter of 14mm, and then cut into an active material layer 20 with a thickness h=230μm. The degree of tightness of the winding is controlled so that the width a of the through hole after winding is 5μm, and the surface mass is 1100mg / 1540.25mm 2After winding, each layer of the self-supporting film is an active material film, and the spacing between each layer of the active material film forms a through hole. The active material layer is compounded with the aluminum foil using conductive glue to obtain the positive electrode film.

[0065] Preparation of the negative electrode film 100:

[0066] The negative active material artificial graphite (365 mAh / g), conductive carbon, and the binder polytetrafluoroethylene (PTFE) are mixed in a weight ratio of 97.5:0.5:2, and the mixture is subjected to a fiberization process, extruded into a film, and cold-pressed to form a negative self-supporting film. The thickness of the film is b = 70 μm. The self-supporting film is wound into a cylinder with a diameter of 16 mm, and cut into an active material layer 20 with a thickness of h = 300 μm. The degree of tightness of the winding is controlled so that the width of the through hole after winding is a = 5 μm, and the surface mass is 570 mg / 1540.25 mm 2 After winding, each layer of the self-supporting film is an active material film, and the spacing between each layer of the active material film forms a through hole. The electrode film is compounded with the copper foil using conductive glue to obtain the negative electrode film 100.

[0067] Preparation of the separator film:

[0068] The separator film substrate is polyethylene (PE) with a thickness of 8 μm. An aluminum oxide ceramic layer with a thickness of 2 μm is coated on both sides of the separator film substrate. Finally, 2.5 mg of the binder polyvinylidene fluoride (PVDF) is coated on both sides of the ceramic layer, and the coated separator film substrate is dried.

[0069] Preparation of the electrolyte:

[0070] In an environment with a water content of less than 10 ppm, lithium hexafluorophosphate and a non-aqueous organic solvent (ethylene carbonate (EC): propylene carbonate (PC): propyl propionate (PP): diethyl carbonate (DEC) = 1:1:1:1, weight ratio) are prepared into a base electrolyte, wherein the concentration of LiPF6 is 1.15 mol / L.

[0071] Preparation of the lithium ion battery:

[0072] The positive electrode film, the separator film, and the negative electrode film are sequentially stacked in order, and the separator film is positioned between the positive electrode film and the negative electrode film to play a role of isolation, so as to form an electrode assembly. The electrode assembly is placed in an outer packaging aluminum plastic film, and after removing the water at 80°C, the electrolyte is injected and packaged. After the processes of formation, degassing, and edge cutting, the lithium ion battery is obtained.

[0073] The preparation processes of Examples Two to Twelve are substantially the same as those of Example One, except that the film height, the film thickness, and the width of the through hole are changed.

[0074] The preparation processes of Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4 and Comparative Example 5 are substantially the same as that of Example 1, except that: in Comparative Example 1, the thickness of the film is 140 μm, which is out of the range of 140 μm to 500 μm set in the present application; in Comparative Example 2, the thickness of the film is 160 μm, which is out of the range of 70 μm to 160 μm set in the present application; in Comparative Example 3, the thickness of the film is 140 μm, which is out of the range of 140 μm to 500 μm set in the present application; in Comparative Example 4, the width of the through hole is 5 μm, which is out of the range of 5 μm to 20 μm set in the present application; in Comparative Example 5, the width of the through hole is 20 μm, which is out of the range of 5 μm to 20 μm set in the present application.

[0075] Comparative Example 1 is different from Example 1 in that the positive electrode sheet and the negative electrode sheet are not provided with through holes, and the rest is the same as Example 1.

[0076] Comparative Example 1:

[0077] Preparation of the positive electrode sheet:

[0078] Lithium cobalt oxide (4.5 V material, specific capacity 180 mAh / g), conductive agent and adhesive polyvinylidene fluoride (PVDF) were dissolved in N-methyl pyrrolidone (NMP) solution in a weight ratio of 97.6:1.1:1.3 to form positive electrode slurry. The positive electrode slurry was coated on an aluminum foil, and the coating thickness was 1100 mg / 1540.25 mm 2 . After drying, cold pressing and slitting, the positive electrode sheet was obtained.

[0079] Preparation of the negative electrode sheet:

[0080] Artificial graphite (365 mAh / g), conductive carbon and adhesive butadiene rubber were dissolved in deionized water in a weight ratio of 97.5:0.5:2 to form negative electrode slurry. Copper foil was used as negative electrode current collector 10, and the negative electrode slurry was coated on the negative electrode current collector 10, with a coating weight of 570 mg / 1540.25 mm 2 . After drying, cold pressing and slitting, the negative electrode sheet was obtained.

[0081] The preparation process of Comparative Example 2 is substantially the same as that of Comparative Example 1, except that the thickness of the active material layer is changed.

[0082] The batteries of the above examples and comparative examples were tested, and the performance of each parameter test is shown in the following table.

[0083] Table 1 Performance of parameter test of examples and comparative examples

[0084]

[0085] Table 2 Performance of parameter test of examples and comparative examples

[0086]

[0087] The surface porosity and the bottom porosity are measured by polishing the cross section of the electrode sheet 100 using an ion mill, taking a cross section photo by a scanning electron microscope backscattering mode, and processing the data of the porosity in the 30 μm thickness region of the surface layer 30 of the active material layer 20 and the porosity in the 30 μm thickness region of the bottom layer of the active material layer using software. The surface layer is the side of the active material layer 20 away from the current collector 10, and the bottom layer is the side of the active material layer 20 close to the current collector 10. The surface porosity and the bottom porosity can be measured by taking a photo of the cross section of the electrode sheet by an electron microscope.

[0088] ED represents energy density.

[0089] 05C discharge capacity: discharge test under 0.5C condition. The capacity / design capacity = discharge capacity, the higher the value obtained by the test, the higher the dynamic performance and energy density of the battery.

[0090] From the data in Table 1, it can be seen that when the membrane height h is consistent, the larger the width a of the through hole, the electrical performance is improved although the energy density is reduced. By comparing the data of Examples 1 to 12 and Comparative Examples 1 to 2, it can be seen that the setting of the active material layer 20 with multiple layers of active material membrane 21, forming a through hole 30 in the active material layer 20, can significantly improve the uniformity of the pores in the electrode sheet 100, and the energy density and dynamic performance of the battery are also significantly improved.

[0091] From the data in Tables 1 and 2, it can be seen that the larger the membrane height h, the smaller the ratio a / b of the width a of the through hole to the thickness b of the membrane, and the larger the ratio h / a of the membrane height h to the width a of the through hole, the higher the energy density of the electrode sheet, even if the electrical performance is reduced. However, for thick electrode sheets, the electrical performance of the electrode sheet in the examples is still better than that of the electrode sheet without a through hole in the comparative examples, fully embodying the superiority of the electrode sheet structure in the present application.

[0092] Referring to Figure 9 The embodiment of the present application also provides an electronic device 300 comprising a power consuming element 301 and the secondary battery 200 described in the above embodiments, wherein the power consuming element 301 is electrically connected to the secondary battery 200.

[0093] The electrode sheet 100, the secondary battery 200 and the electronic device 300 of the present application, by setting the active material layer 20 with the multi-layer active material film 21, forming the through-hole 30 of the active material layer 20 in the active material layer 20, the ions can be quickly transmitted in the through-hole 30, thereby improving the kinetic performance of the thick electrode sheet. In addition, the active material layer 20 formed by winding or stacking the multi-layer active film and then cutting has the characteristics of controllable thickness and uniform internal material porosity, which can further improve the dynamic cycle performance of the thick electrode sheet and improve the manufacturing quality of the thick electrode sheet.

[0094] The above embodiments are only used to illustrate the technical solutions of the present application and not to limit the present application. Although the present application has been described in detail with reference to the above preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced without departing from the spirit and scope of the present application.

Claims

1. An electrode sheet, characterized by, It comprises: a current collector; and an active material layer provided on the surface of the current collector, the active material layer comprising a plurality of active material films, any two adjacent active material films being provided with a spacing to form a through hole, the through hole penetrating the active material layer in a direction perpendicular to the surface of the current collector; the thickness of each active material film in a direction parallel to the surface of the current collector being 70-160 μm, and the width of the through hole being 5-20 μm; the height of each active material film in a direction perpendicular to the surface of the current collector being 140-500 μm.

2. The electrode sheet according to claim 1, wherein: the height of the active material film is 200-400 μm.

3. The electrode sheet according to claim 1, wherein: the height of the active material film is 200-300 μm.

4. The electrode sheet according to claim 1, wherein: the width of the through hole is greater than 5 μm and less than 10 μm.

5. The electrode sheet according to claim 1, wherein: the ratio of the height of the active material film to the width of the through hole is 7.5-100.

6. The electrode sheet according to claim 5, wherein: the ratio of the thickness of the active material film to the width of the through hole is 17-50.

7. The electrode sheet according to claim 1, wherein: the difference in porosity between the surface layer and the bottom layer of the active material film is less than 3%.

8. The electrode sheet according to claim 1, wherein: the active material layer comprises a binder, and the binder is fibrous.

9. The electrode sheet according to claim 8, wherein: the electrode sheet is bendable, and the bending curvature radius of the electrode sheet is greater than 1.5 mm.

10. A method for manufacturing an electrode sheet for manufacturing the electrode sheet according to any one of claims 1 to 9, characterized by, The method for manufacturing the electrode sheet comprises: mixing active material particles and a fibrous binder to prepare an active material support film; winding or stacking or layer-by-layer winding the active material support film to form an active material column, and slicing the active material column to obtain an active material layer having a plurality of active material films, any two adjacent active material films forming a through hole therebetween; compositing the active material layer on the surface of a current collector.

11. A secondary battery characterized by comprising: The secondary battery comprises a package and an electrode sheet according to any one of claims 1-9, the electrode sheet being provided in the package.

12. An electronic device, comprising: The secondary battery comprises a secondary battery according to claim 11 and a use element, the use element being electrically connected to the secondary battery.

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