Battery pole piece and battery cell

Abstract

The utility model discloses a battery pole piece and a battery cell, the pole piece comprises a current collector, at least one surface of the current collector along the thickness direction is provided with a coated area and an uncoated area, the coated area and the uncoated area are arranged at an interval along the length direction of the current collector, and the uncoated area is provided with a first through hole along the thickness direction of the current collector; the first active layer is arranged on the surface of the current collector coating region, and a second through hole is formed in the first active layer along the thickness direction; the second active layer is arranged on one surface, far away from the current collector, of the first active layer; and the second active layer penetrates through the second through hole and is connected with the current collector. A battery cell prepared from the pole piece comprises a plurality of through holes in the corner area, and by regulating and controlling the area proportion, size and the like of the through holes in the coated area and the uncoated area of the pole piece, the energy density of the battery can be effectively improved, the exertion of active substances can be improved, and the problems that lithium is easy to separate out in the corner area, the internal resistance of the battery is increased and the like are solved; and the battery has excellent rate capability and cycle performance.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to a battery electrode and a battery cell. Background Technology

[0002] With the development of lithium-ion batteries, the requirements for battery energy density and functionality are becoming increasingly stringent. To ensure high energy density, high-density solid graphite is commonly used as the negative electrode active material. However, when batteries using this material are charged at high rates, due to the characteristics of high-density solid graphite, the corners of the cell are difficult to be fully wetted by the electrolyte, and the active material cannot fully exert its potential. This often leads to lithium plating on the negative electrode at the corners of the cell, making it difficult for lithium-ion batteries to achieve high energy density, fast charging, and long cycle life. Utility Model Content

[0003] To address the aforementioned issues, this invention provides a battery electrode and cell. Through a structural design with a double-layer active layer and spaced coated and uncoated areas, combined with appropriately sized and proportioned through-holes in the uncoated area of ​​the current collector and in the first active layer close to the current collector surface, the energy density of the battery can be effectively improved while enhancing the utilization of active materials. This also solves problems such as easy lithium deposition in corner areas and increased internal resistance, enabling the battery to possess both excellent rate performance and cycle performance.

[0004] Specifically, the following technical solutions are provided:

[0005] The first aspect of this utility model provides a battery electrode, comprising:

[0006] A current collector has a coated area and an uncoated area on both sides along the thickness direction. The coated area and the uncoated area are spaced apart along the length direction of the current collector, and the uncoated area has a first through hole along the thickness direction of the current collector. The first through hole includes one or more spaced first sub-through holes.

[0007] A first active layer is disposed on the surface of the coated area, the first active layer having a second through-hole along its thickness direction, the second through-hole comprising one or more spaced second sub-through-holes; and

[0008] A second active layer is disposed on the side of the first active layer away from the current collector, and a portion of the second active layer passes through the second through hole and is connected to the current collector;

[0009] The total area of ​​the first through-hole accounts for 5%-40% of the total area of ​​the uncoated area; the total area of ​​the second through-hole accounts for 2%-20% of the total area of ​​the coated area.

[0010] In this invention, the current collector of the battery electrode is provided with a coated area and an uncoated area. The coated area corresponds to the straight area of ​​the wound battery cell, and the uncoated area corresponds to the corner area of ​​the wound battery cell. By providing a first through hole in the uncoated area, the wound battery cell can promote the wetting of the electrode by the electrolyte through the through hole structure at the corner, thus improving the lithium plating problem. In addition, an active layer is provided on the surface of the coated area, including a first active layer that is attached to the surface of the coated area of ​​the current collector and a second active layer disposed on the side of the first active layer away from the current collector. The first active layer is provided with an appropriate number of second through holes, so that the second active layer can partially pass through the second through holes to contact the current collector. On the one hand, this rivet structure formed by the first active layer and the second active layer is conducive to improving the peel strength between the active layer and the current collector, and on the other hand, it is conducive to improving the performance of the active material in the second active layer, shortening the lithium ion transport path during charging and discharging, reducing energy loss, and improving rate performance.

[0011] In this invention, the proportion of the total area of ​​the first through-hole in the uncoated area needs to be controlled. If the proportion of the first through-hole in the uncoated area is too large, it will affect the strength of the current collector and reduce the electronic conductivity of the current collector, thus affecting battery performance. If the proportion of the first through-hole in the uncoated area is too small, the penetration effect of the electrolyte at the corner of the cell will not be well improved, and the problem of lithium plating at the corner cannot be effectively solved. Therefore, the proportion of the total area of ​​the first through-hole in the uncoated area needs to be controlled in the range of 5%-40%, such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, etc., including but not limited to the proportions listed above, so that the battery can take into account high energy density, rate performance and excellent cycle performance.

[0012] In this invention, the proportion of the total area of ​​the second through hole in the coating area affects the energy density and rate performance of the battery. If the total area of ​​the second through hole is too large, it will reduce the energy density of the battery (the areal density of the first active layer attached to the current collector surface is usually large); however, if the total area of ​​the second through hole is too small, it will affect the overall peel strength of the active layer and the rate performance of the battery. Therefore, the total area of ​​the second through hole should account for 2%-20% of the total area of ​​the coating area, such as 2%, 5%, 10%, 15%, 20%, etc., so that the battery can take into account high energy density, rate performance and excellent cycle performance.

[0013] In some preferred embodiments of this utility model, the total area of ​​the first through hole accounts for 10-30% of the total area of ​​the uncoated area; the total area of ​​the second through hole accounts for 5-15% of the total area of ​​the coated area.

[0014] In some preferred embodiments of this utility model, the current collector is a composite current collector, which includes a base film and metal layers disposed on the upper and lower surfaces of the base film. Preferably, the thickness of the composite current collector is 2-25 μm, such as 2 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, etc. The base film can be a PP film, a PET film, or a PI film, or other film materials conventionally used in the art. More preferably, a PET film is used as the base film. The hardness of the PET film is beneficial to improving the strength at the corners of the battery cell, avoiding the slowdown of lithium-ion transport due to collapse, improving the lithium-ion transport rate, and improving battery performance.

[0015] In some preferred embodiments of this utility model, the aperture size of the first sub-through hole is preferably 100-2000μm, such as 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 800μm, 1000μm, 1200μm, 1400μm, 1500μm, 1600μm, 1800μm, 2000μm, etc. The aperture of the first sub-through hole located in the uncoated area of ​​the current collector should not be too large or too small. If the aperture is too large, it will affect the strength of the current collector, especially the strength at the corner of the cell. If the aperture is too small, it will affect the penetration effect of the electrolyte. More preferably, the aperture size of the first sub-through hole is 1000-2000μm. In addition, the aperture size of the second sub-through hole is preferably 10-100μm, such as 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, or 100μm. If the aperture of the second sub-through hole is too small, it will increase the difficulty of drilling and coating, while if the aperture is too large, it will not be able to effectively improve the rate performance of the battery. More preferably, the aperture size of the second sub-through hole is 50-100μm.

[0016] In some preferred embodiments of this utility model, the shape of the first sub-through hole is circular, elliptical, square, rectangular or triangular, and the shape of the second sub-through hole is circular, elliptical, square, rectangular or triangular. The shapes of the first sub-through hole and the second sub-through hole may be the same or different.

[0017] The second aspect of this utility model provides a core comprising a positive electrode sheet, a separator, and a negative electrode sheet, wherein the positive electrode sheet and the negative electrode sheet are both battery electrode sheets as described in the first aspect.

[0018] In some preferred embodiments of this utility model, in the winding core, the coating area of ​​the positive electrode sheet overlaps with the coating area of ​​the negative electrode sheet, the uncoated area of ​​the positive electrode sheet overlaps with the uncoated area of ​​the negative electrode sheet, and the through holes provided in the uncoated areas of the positive electrode sheet and the negative electrode sheet overlap accordingly.

[0019] In some preferred embodiments of this utility model, the core includes a straight area and a corner area; the coated areas of the positive electrode sheet and the negative electrode sheet are located in the straight area of ​​the core, and the uncoated areas of the positive electrode sheet and the negative electrode sheet are located in the corner area of ​​the core.

[0020] In some preferred embodiments of this invention, the first active layer of the positive electrode sheet is composed of a first positive electrode active material, a first conductive agent, and a first binder, and the second active layer of the positive electrode sheet is composed of a second positive electrode active material, a second conductive agent, and a second binder; wherein...

[0021] The first positive electrode active material and the second positive electrode active material are preferably one or more of lithium cobalt oxide, lithium iron phosphate, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium-rich manganese-based materials, lithium nickel manganese oxide and lithium titanate, respectively.

[0022] The first conductive agent and the second conductive agent are preferably one or more of conductive graphite, carbon fiber, carbon nanotubes and graphene, respectively.

[0023] The first adhesive and the second adhesive are preferably polyvinylidene fluoride.

[0024] In some preferred embodiments of this utility model, the first active layer of the negative electrode sheet is composed of a first negative electrode active material, a conductive agent A, and a binder A, and the second active layer of the negative electrode sheet is composed of a second negative electrode active material, a conductive agent B, and a binder B; wherein...

[0025] The first negative electrode active material and the second negative electrode active material are preferably one or more of graphite, coke, fibrous carbon, mesophase carbon microspheres, carbon black, silicon-based oxides, silicon-carbon composite materials, lithium titanate and nano-carbon;

[0026] The conductive agent A and the conductive agent B are preferably one or more of carbon black, conductive graphite, carbon fiber, carbon nanotubes and graphene, respectively.

[0027] The adhesive A and the adhesive B are preferably one or more of polyvinylidene fluoride, sodium carboxymethyl cellulose and styrene-butadiene rubber.

[0028] In some preferred embodiments of this utility model, the mass ratio of active material, conductive agent, and binder in the positive electrode and / or negative electrode is (95%-98%):(0.5%-1%):(0.5%-1%).

[0029] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0030] This invention provides a battery electrode with a structure design consisting of a double active layer and spaced coated and uncoated areas. By incorporating appropriately sized and proportioned through-holes in the uncoated area of ​​the current collector and on the first active layer close to the current collector surface, the assembled battery core, while possessing high energy density, effectively enhances the performance of the active material. Furthermore, the through-hole design at the corner of the cell in the uncoated area of ​​the electrode effectively promotes electrolyte penetration and wetting, mitigating issues such as easy lithium deposition at the cell corner and increased internal resistance. This allows the lithium-ion battery to achieve a balance of high energy density, rate performance, and excellent cycle performance. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a battery electrode provided by this utility model;

[0032] Figure 2 A schematic diagram of the structure of a winding core provided by this utility model;

[0033] Explanation of reference numerals in the accompanying drawings: 01, positive electrode; 02, separator; 03, negative electrode; 001, straight area; 002, corner area; 1, current collector; 11, coated area; 12, uncoated area; 121, first through-hole; 1211, first sub-through-hole; 2, active layer; 21, first active layer; 211, second through-hole; 2111, second sub-through-hole; 22, second active layer. Detailed Implementation

[0034] 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 invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items. The terms “comprising” or “including” as used herein may also be replaced with the closed form “is” or “consisting of”.

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments are not intended to limit the present invention.

[0036] Example 1

[0037] Reference Figure 1 , Figure 2As shown, Embodiment 1 of this utility model provides a battery electrode and a winding core. The battery electrode includes a current collector 1, on which coated areas 11 and uncoated areas 12 are provided on both sides along the thickness direction. The coated areas 11 and uncoated areas 12 are spaced apart along the length direction of the current collector 1, and the uncoated areas 12 are provided with a first through hole 121 along the thickness direction of the current collector 1. The first through hole 121 includes a plurality of spaced first sub-through holes 1211. The battery electrode also includes an active layer 2, which includes a first active layer 21 and a second active layer 22. The first active layer 21 is disposed on the surface of the coated area, and the second active layer 22 is disposed on the side of the first active layer 21 away from the current collector 1. The first active layer 21 is provided with a second through hole 211 along the thickness direction. The second through hole 21 includes a plurality of spaced second sub-through holes 2111. The second active layer 22 partially passes through the second through hole 211 and is connected to the current collector 1.

[0038] This embodiment also provides a core comprising the aforementioned positive electrode 01, separator 02, and negative electrode 03. The coated areas of the positive electrode 01 and the negative electrode 03 overlap, and the uncoated areas of the positive electrode 01 and the negative electrode 03 overlap. Furthermore, the through holes provided in the uncoated areas of the positive electrode 01 and the negative electrode 03 overlap. The coated areas of the positive and negative electrodes are located in the straight areas 001 of the core, and the uncoated areas of the positive and negative electrodes are located in the corner areas 002 of the core. Through the through holes in the corner areas, the electrolyte can quickly penetrate and wet the core.

[0039] In this embodiment, the preparation of the positive electrode 01 includes the following steps:

[0040] A 6μm thick aluminum foil was used as the positive electrode current collector. The positive electrode active material (lithium nickel cobalt manganese oxide), conductive carbon, and binder PVDF were mixed at a mass ratio of 97%:2%:1%. NMP was added and stirred evenly to obtain a positive electrode active slurry. The positive electrode active slurry was coated on the coating areas on both sides of the composite aluminum foil (the coating areas have uncoated areas of equal width at both ends along the length direction, and the area ratio of the coating area to the uncoated area is 20:1). After drying, a first active layer with a thickness of 0.124mm was obtained. The first active layer was perforated to obtain through holes (circular, with a diameter of 50μm) that were uniformly and spaced apart. The area of ​​the through holes was 10% of the area of ​​the coating area.

[0041] The above-mentioned positive electrode active slurry is coated on the first active layer and dried to obtain a second active layer with a thickness of 0.109 mm. Then, a perforation process is performed in the uncoated area to obtain through holes (circular with a diameter of 1000 μm) that are uniformly and spaced apart. The area of ​​the through holes is 20% of the area of ​​the uncoated area, thus obtaining the positive electrode sheet.

[0042] In this embodiment, the preparation of the negative electrode plate O2 includes the following steps:

[0043] A 6μm thick composite copper foil (with PET as the base film) was used as the negative electrode current collector. Graphite, conductive carbon, PVDF binder, and CMC thickener were mixed in a mass ratio of 96.5%:1.2%:1.5%:0.8%, and water was added and stirred until homogeneous to obtain a negative electrode slurry. This slurry was coated onto the coated areas on both sides of the composite copper foil (the coated areas had uncoated areas of equal width at both ends along the length direction, with a coated area to uncoated area ratio of 20:1). After drying, a first active layer with a thickness of 0.112mm was obtained. A perforation process was performed on the first active layer to obtain uniformly spaced through holes (circular, with a diameter of 50μm). The area of ​​the through holes was 10% of the area of ​​the coated area.

[0044] The above-mentioned negative electrode active slurry is coated on the first active layer and dried to obtain a second active layer with a thickness of 0.098 mm. Then, a perforation process is performed in the uncoated area to obtain through holes (circular with a diameter of 1000 μm) that are uniformly and spaced apart. The area of ​​the through holes is 20% of the area of ​​the uncoated area, thus obtaining the negative electrode sheet.

[0045] In this embodiment, the preparation of the core includes the following steps:

[0046] After the prepared positive and negative electrode sheets are rolled, the positive and negative electrode sheets are separated by a separator and then wound. The wound electrode sheets are then placed into an aluminum shell and the top cover is welded and sealed.

[0047] The electrolyte (13% LiPF6, EC / EMC = 3 / 7; 2% PS + 1% DTD + 0.8% LiPO2F2) was injected into the winding core and then allowed to stand at room temperature and high temperature.

[0048] After the core undergoes chemical aging, it is injected with liquid a second time and divided into volumes, thus completing the assembly and preparation of the core.

[0049] Example 2

[0050] This embodiment relates to a battery electrode sheet and a winding core. The only difference from Embodiment 1 is that the diameter of the first through hole is 1000 μm and the area of ​​the through hole is 40% of the area of ​​the uncoated area, and the diameter of the second through hole is 50 μm and the area of ​​the through hole is 20% of the area of ​​the coated area; the rest of the operations are the same, and the corresponding winding core is obtained.

[0051] Example 3

[0052] This embodiment relates to a battery electrode sheet and a winding core. The only difference from Embodiment 1 is that the diameter of the first through hole is 1000 μm and the area of ​​the through hole is 5% of the area of ​​the uncoated area; the diameter of the second through hole is 50 μm and the area of ​​the through hole is 5% of the area of ​​the coated area; the rest of the operations are the same, and the corresponding winding core is obtained.

[0053] Example 4

[0054] This embodiment relates to a battery electrode sheet and a winding core. The only difference from Embodiment 1 is that the diameter of the first through hole is 100 μm and the area of ​​the through hole is 20% of the area of ​​the uncoated area; the diameter of the second through hole is 10 μm and the area of ​​the through hole is 10% of the area of ​​the coated area; the rest of the operations are the same, and the corresponding winding core is obtained.

[0055] Example 5

[0056] This embodiment relates to a battery electrode sheet and a winding core. The only difference from Embodiment 1 is that the diameter of the first through hole is 2000 μm and the area of ​​the through hole is 20% of the area of ​​the uncoated area; the diameter of the second through hole is 100 μm and the area of ​​the through hole is 10% of the area of ​​the coated area; the rest of the operations are the same, and the corresponding winding core is obtained.

[0057] Example 6

[0058] This embodiment relates to a battery electrode sheet and a winding core. The only difference from Embodiment 1 is that the diameter of the first through hole is 2000 μm and the area of ​​the through hole is 5% of the area of ​​the uncoated area; the diameter of the second through hole is 100 μm and the area of ​​the through hole is 5% of the area of ​​the coated area; the rest of the operations are the same, and the corresponding winding core is obtained.

[0059] Example 7

[0060] This embodiment relates to a battery electrode sheet and a winding core. The only difference from Embodiment 1 is that the diameter of the first through hole is 2000 μm and the area of ​​the through hole is 5% of the area of ​​the uncoated area; the diameter of the second through hole is 100 μm and the area of ​​the through hole is 20% of the area of ​​the coated area; the rest of the operations are the same, and the corresponding winding core is obtained.

[0061] Example 8

[0062] This embodiment relates to a battery electrode sheet and a winding core. The only difference from Embodiment 1 is that the diameter of the first through hole is 2000 μm and the area of ​​the through hole is 20% of the area of ​​the uncoated area; the diameter of the second through hole is 100 μm and the area of ​​the through hole is 5% of the area of ​​the coated area; the rest of the operations are the same, and the corresponding winding core is obtained.

[0063] Comparative Example 1

[0064] This comparative example relates to a battery electrode and a winding core. The only difference from Example 1 is that the first active layer and the uncoated area are not perforated; the rest of the operations are the same, resulting in the corresponding winding core.

[0065] Comparative Example 2

[0066] This comparative example relates to a battery electrode and a winding core. The only difference from Example 1 is that the diameter of the first through hole is 3000 μm and the area of ​​the through hole is 20% of the area of ​​the uncoated area; the rest of the operations are the same, and the corresponding winding core is obtained.

[0067] Comparative Example 3

[0068] This comparative example relates to a battery electrode and a winding core. The only difference from Example 1 is that the diameter of the first through hole is 1000 μm and the area of ​​the through hole is 50% of the area of ​​the uncoated area; the rest of the operations are the same, and the corresponding winding core is obtained.

[0069] Comparative Example 4

[0070] This comparative example relates to a battery electrode and a winding core. The only difference from Example 1 is that the diameter of the second through hole is 200 μm and the area of ​​the through hole is 10% of the area of ​​the coating area; the rest of the operations are the same, and the corresponding winding core is obtained.

[0071] Comparative Example 5

[0072] This comparative example relates to a battery electrode and a winding core. The only difference from Example 1 is that the diameter of the second through hole is 50 μm and the area of ​​the through hole is 30% of the area of ​​the coating area; the rest of the operations are the same, and the corresponding winding core is obtained.

[0073] The aperture size and area ratio of the first through-hole in Examples 1-8 and Comparative Examples 1-5, as well as the aperture size and area ratio of the uncoated area in the positive / negative electrode sheets, are shown in Table 1 below:

[0074] Table 1

[0075]

[0076] Performance testing

[0077] The capacity, rate performance, and cycle performance of the batteries prepared in the above embodiments and comparative examples were tested using the following methods:

[0078] (1) Capacity test: After standing at 25℃ for 5 minutes, discharge at 1C to 2.5V, stand for 15 minutes, charge at 1C constant current to 4.4V, stand for 15 minutes, discharge at 1C to 2.5V, and record the measured capacity C0; then stand for 15 minutes, discharge at 0.2C to 2.5V, and record the measured capacity C1; then stand for 15 minutes, charge at 0.33C constant current to 4.4V, and stand for 15 minutes.

[0079] (2) Rate performance test: After standing at 25℃ for 5 minutes, discharge at 1C to 2.5V, stand for 30 minutes, charge at 1C constant current to 4.4V, stand for 30 minutes, and record the charging capacity. Then discharge at 1C, 3C, 5C and 10C to 2.5V respectively, record the discharge capacity of the cell at different discharge rates, and calculate the coulombic efficiency at different discharge rates. Coulombic efficiency = discharge capacity / 1C discharge capacity × 100%.

[0080] (3) Cyclic performance test: After standing at 25℃ for 5 minutes, the battery was discharged at 1C to 2.5V, stood for 15 minutes, charged at 1C constant current to 4.4V, stood for 15 minutes, and discharged at 1C to 2.5V. This charge-discharge process was repeated for 100, 200, 300, and 500 cycles. The capacity C of each battery at different cycle numbers was recorded. 循环 Calculate the capacity retention rate: Capacity retention rate = C 循环 / C1×100%.

[0081] The results of the above performance tests are shown in Table 2 below:

[0082] Table 2

[0083]

[0084] As shown in Table 2, compared with Comparative Example 1, the cores prepared by Examples 1-8, by setting through holes of appropriate proportion and size in the first active layer and uncoated area of ​​the positive and negative electrodes, exhibit higher specific capacity, rate performance and better cycle performance under the same test conditions.

[0085] As shown in Example 1 and Comparative Example 2, when the diameter of the first through-hole in the uncoated area is too large, the specific capacity of the prepared core (Comparative Example 2) is not significantly different from that of Example 1, but the rate performance and cycle performance are significantly deteriorated. Furthermore, as shown in Example 1 and Comparative Example 3, when the total area ratio of the first through-hole in the uncoated area is too large, the specific capacity of the core will decrease, and the rate performance and cycle performance of the core will also deteriorate.

[0086] As can be seen from Example 1 and Comparative Examples 4 and 5, if the size of the second through-hole on the first active layer of the positive / negative electrode sheet is too large or its total area ratio is too large, the specific capacity, rate performance, and cycle performance of the prepared core will all decrease significantly.

[0087] The above-described embodiments are merely preferred examples provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A battery electrode, characterized in that, The battery electrode includes: A current collector (1) is provided with a coated area (11) and an uncoated area (12) on both sides along the thickness direction. The coated area (11) and the uncoated area (12) are spaced apart along the length direction of the current collector (1). The uncoated area (12) is provided with a first through hole (121) along the thickness direction of the current collector (1). The first through hole (121) includes one or more spaced first sub-through holes (1211). A first active layer (21) is disposed on the surface of the coating area (11), the first active layer (21) having a second through hole (211) along the thickness direction, the second through hole (211) including one or more spaced second sub-through holes (2111); and A second active layer (22) is disposed on the side of the first active layer (21) away from the current collector (1), and the second active layer (22) partially passes through the second through hole (211) and is connected to the current collector (1); The total area of ​​the first through hole (121) accounts for 5%-40% of the total area of ​​the uncoated area (12); the total area of ​​the second through hole (211) accounts for 2%-20% of the total area of ​​the coated area (11).

2. The battery electrode according to claim 1, characterized in that, The total area of ​​the first through hole (121) accounts for 10-30% of the total area of ​​the uncoated area (12); the total area of ​​the second through hole (211) accounts for 5-15% of the total area of ​​the coated area (11).

3. The battery electrode according to claim 1, characterized in that, The current collector (1) is a composite current collector, which includes a base film and a metal layer disposed on the upper and lower surfaces of the base film.

4. The battery electrode according to claim 3, characterized in that, The thickness of the composite current collector is 2-25 μm; the base film is a PP film, a PET film, or a PI film.

5. The battery electrode according to claim 1, characterized in that, The diameter of the first sub-through hole (1211) is 100-2000μm, and the diameter of the second sub-through hole (2111) is 10-100μm.

6. The battery electrode according to claim 5, characterized in that, The diameter of the first sub-through hole (1211) is 1000-2000μm, and the diameter of the second sub-through hole (2111) is 50-100μm.

7. The battery electrode according to claim 5, characterized in that, The first sub-through hole (1211) is circular, elliptical, square, rectangular or triangular in shape; The second sub-hole (2111) is circular, elliptical, square, rectangular or triangular in shape.

8. A wound core comprising a positive electrode (01), a separator (02), and a negative electrode (03), characterized in that, Both the positive electrode (01) and the negative electrode (03) are battery electrodes as described in any one of claims 1-7.

9. The winding core according to claim 8, characterized in that, The coating area of ​​the positive electrode (01) overlaps with the coating area of ​​the negative electrode (03), the uncoated area of ​​the positive electrode (01) overlaps with the uncoated area of ​​the negative electrode (03), and the through holes provided in the uncoated areas of the positive electrode (01) and the negative electrode (03) overlap.

10. The winding core according to claim 8 or 9, characterized in that, The core includes a straight area (001) and a corner area (002); the coated areas of the positive electrode (01) and the negative electrode (03) are located in the straight area (001) of the core, and the uncoated areas of the positive electrode (01) and the negative electrode (03) are located in the corner area (002) of the core.

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