Current collector, electrode, cell and battery pack

Abstract

This utility model relates to the field of battery technology and discloses a current collector, electrode, battery cell, and battery pack. The current collector includes a base film and a metal layer. The surface of the base film has multiple pores, which are sequentially divided into a first open area, a transition area, and a second open area. The opening area and / or opening density of the multiple pores gradually increase in the first, transition, and second open areas. The metal layer is disposed on opposite sides of the base film in the thickness direction. This utility model provides pores with gradually increasing opening area and / or opening density in the first, transition, and second open areas, allowing the metal layer to penetrate into the pores, improving the adhesion between the metal layer and the base film. The pores also allow electrolyte to penetrate, playing a role in electrolyte retention and improving the battery cell's lifespan. Furthermore, the gradually increasing opening area and / or opening density can be adapted to the current density distribution, improving current carrying capacity and reducing the battery cell's internal resistance.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to current collectors, electrode sheets, battery cells, and battery packs. Background Technology

[0002] Composite foil, as an important material, has wide applications in energy storage devices such as batteries and capacitors. Composite foil used as a current collector in new energy battery packs is a composite material consisting of three layers: a copper / aluminum layer, a base film, and another copper / aluminum layer. This composite material has a lighter weight and better safety performance, which can improve the energy density and safety of the battery.

[0003] Existing composite foils, after being coated with positive / negative electrode pastes (active material layers) and rolled, have low peel strength, are difficult to use for long-term recycling, have a short service life, and have high internal resistance. Utility Model Content

[0004] In view of this, the present invention provides a current collector, electrode, battery cell and battery pack to solve the problems of low service life and high internal resistance of existing composite foil materials as battery current collectors.

[0005] Firstly, this utility model provides a current collector, comprising:

[0006] The base film has a plurality of membrane pores extending along the thickness direction on its surface. The base film is divided into a first opening region, a transition region and a second opening region along its length direction. The opening area and / or opening density of the plurality of membrane pores gradually increase in the first opening region, the transition region and the second opening region.

[0007] Metal layers are disposed on opposite sides of the base film in the thickness direction.

[0008] Beneficial Effects: The current collector of this invention features membrane pores with gradually increasing pore area and / or pore density in the first, transition, and second opening regions. This allows the metal layer to penetrate into the pores, increasing the adhesion area between the metal layer and the base film, thereby enhancing their bonding strength. Furthermore, the pores also form diffusion channels for the electrolyte. After the electrolyte penetrates the pores, it helps retain electrolyte, preventing problems such as lithium plating and electrolyte leakage due to insufficient electrolyte, thus extending the current collector's lifespan. Additionally, the gradually increasing pore area and / or pore density, adapted to the current density distribution, also improves current carrying capacity and reduces the cell's internal resistance.

[0009] In one optional embodiment, the membrane pore includes a plurality of first sub-pores disposed in the first opening region. The first sub-pores are circular holes with a diameter of Φ1. The ratio of the total opening area of ​​each first sub-pore to the area of ​​the first opening region is P1, which satisfies 2μm≤Φ1≤20μm and 5%≤P1≤15%.

[0010] Beneficial effects: By controlling the diameter of the first sub-hole and the ratio of the total opening area of ​​each first sub-hole to the area of ​​the first opening region, it is possible to ensure that the metal layer partially penetrates into the first sub-hole in the first opening region, thereby improving the adhesion between the metal layer and the base film.

[0011] In one alternative embodiment, the first sub-hole is a through hole or a blind hole, and the metal layer partially penetrates into the first sub-hole.

[0012] Beneficial effects: Setting the first sub-hole as a through hole or blind hole facilitates the penetration of the metal layer into the first sub-hole, thereby increasing the bonding area between the metal layer and the base film and improving the bonding strength between the metal layer and the base film.

[0013] In one optional embodiment, the membrane pore includes a plurality of second sub-pores disposed in the transition region, and along the length direction, the opening area and the number of openings of the plurality of second sub-pores gradually increase from the first opening region to the second opening region.

[0014] Beneficial effects: The transition area can act as a buffer, preventing uneven stretching during rolling and causing wrinkles on the electrode sheets.

[0015] In one optional embodiment, the second sub-hole is a circular hole with a diameter of Φ2. The ratio of the total opening area of ​​each second sub-hole to the area of ​​the transition region is P2, satisfying 10μm≤Φ2≤40μm and 10%≤P2≤30%.

[0016] Beneficial effect: By controlling the diameter of the second sub-hole and the ratio of the total opening area of ​​each second sub-hole to the area of ​​the transition region, it is possible to ensure that the transition region plays a buffering role.

[0017] In one optional embodiment, the membrane pore includes a plurality of third sub-pores disposed in the second opening region. The third sub-pores are circular holes with a diameter of Φ3. The ratio of the total opening area of ​​each third sub-pore to the area of ​​the second opening region is P3, which satisfies 30μm≤Φ3≤100μm and 25%≤P3≤35%.

[0018] Beneficial effects: By controlling the diameter of the third sub-hole and the ratio of the total area of ​​each third sub-hole to the area of ​​the second opening region, it is possible to ensure that the metal layers on opposite sides of the base film thickness direction are in contact and welded and fixed in the third sub-hole.

[0019] In one optional embodiment, the third sub-hole is a through-hole, in which two metal layers located on opposite sides of the base film thickness direction partially penetrate into and connect to the third sub-hole.

[0020] Beneficial effects: By setting the third sub-hole as a through-hole, the metal layers on both sides of the base film thickness direction can be welded together through the third sub-hole to form a conductive path, which can reduce internal resistance. Moreover, it also reduces the steps of additionally connecting different electrodes by welding, thereby improving the processing efficiency of the electrodes and reducing manufacturing costs.

[0021] In one optional embodiment, the length of the first opening region is L1, which satisfies 100mm≤L1≤1000mm;

[0022] And / or, the length of the transition region is L2, satisfying 5mm≤L2≤10mm;

[0023] And / or, the length of the second opening area is L3, satisfying 10mm≤L3≤40mm.

[0024] Beneficial effects: By controlling the length of the first opening area, the length of the transition area, and the length of the second opening area, it is possible to ensure that the first opening area has sufficient length to bond with the metal layer, that the transition area has sufficient length to provide buffer protection, and that the two metal layers are welded and fixed in the second opening area to form a conductive path.

[0025] Secondly, this utility model also provides an electrode sheet, comprising:

[0026] Active material layer;

[0027] The aforementioned current collector has the active material layer coated on at least one side of the first opening region and the transition region in the thickness direction.

[0028] Beneficial effects: The electrode of this invention features membrane pores with gradually increasing pore area and / or pore density in the first, transition, and second opening regions. This allows the metal layer to penetrate into the pores, increasing the adhesion area between the metal layer and the base film, thereby enhancing their bonding strength. Furthermore, the pores also form diffusion channels for the electrolyte. After the electrolyte penetrates the pores, it helps retain electrolyte, preventing problems such as lithium plating and electrolyte leakage due to insufficient electrolyte, thus extending the lifespan of the current collector. Additionally, the gradually increasing pore area and / or pore density, adapted to the current density distribution, also improves current carrying capacity and reduces the cell's internal resistance.

[0029] Thirdly, this utility model also provides a battery cell, comprising: at least one of the above-mentioned electrode sheets.

[0030] Beneficial Effects: The battery cell of this invention features membrane pores with gradually increasing pore area and / or pore density in the first opening region, transition region, and second opening region. This allows the metal layer to penetrate into the membrane pores, increasing the adhesion area between the metal layer and the base film, thereby enhancing their bonding strength. Furthermore, the membrane pores also form diffusion channels for the electrolyte. After the electrolyte penetrates the membrane pores, it helps retain electrolyte, preventing problems such as lithium plating and electrolyte leakage caused by insufficient electrolyte, thus extending the service life of the current collector. Additionally, the gradually increasing pore area and / or pore density, adapted to the current density distribution, also improves the overcurrent capacity and reduces the internal resistance of the battery cell.

[0031] Fourthly, the present invention also provides a battery pack, comprising: at least one of the above-mentioned battery cells.

[0032] Beneficial Effects: The battery pack of this invention features membrane pores with gradually increasing pore area and / or pore density in the first opening region, transition region, and second opening region. This allows the metal layer to penetrate into the membrane pores, increasing the adhesion area between the metal layer and the base film, thereby enhancing their bonding strength. Furthermore, the membrane pores also form diffusion channels for the electrolyte. After the electrolyte penetrates the membrane pores, it helps retain electrolyte, preventing problems such as lithium plating and electrolyte leakage due to insufficient electrolyte, thus extending the lifespan of the current collector. Additionally, the gradually increasing pore area and / or pore density, adapted to the current density distribution, also improves overcurrent capacity and reduces the internal resistance of the battery cell. Attached Figure Description

[0033] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 This is a cross-sectional view of a current collector according to an embodiment of the present utility model;

[0035] Figure 2 This is a cross-sectional view of a current collector base membrane according to an embodiment of the present invention.

[0036] Explanation of reference numerals in the attached figures:

[0037] 1. Base film; 101. First opening region; 102. Transition region; 103. Second opening region; 2. Membrane pore; 201. First sub-pore; 202. Second sub-pore; 203. Third sub-pore; 3. Metal layer. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0039] A current collector is a structure or component that collects electric current; it is an indispensable part for connecting lithium-ion batteries and external circuits.

[0040] The following is combined Figures 1 to 2 The following describes embodiments of the present invention.

[0041] According to an embodiment of the present invention, in a first aspect, as follows: Figure 1 As shown, a current collector is provided, mainly comprising: a base film 1 and a metal layer 3. The surface of the base film 1 has a plurality of membrane pores 2 extending along the thickness direction. The base film 1 is sequentially divided into a first opening region 101, a transition region 102, and a second opening region 103 along its length direction. The opening area and / or opening density of the plurality of membrane pores 2 gradually increase in the first opening region 101, the transition region 102, and the second opening region 103. The metal layer 3 is disposed on opposite sides of the base film 1 in the thickness direction.

[0042] Therefore, the current collector provided in this embodiment of the present invention, with membrane pores 2 having gradually increasing opening areas and / or opening densities in the first opening region 101, transition region 102, and second opening region 103, allows the metal layer 3 to penetrate into the membrane pores 2, increasing the adhesion area between the metal layer 3 and the base film 1, thereby enhancing the adhesion strength between the two. Furthermore, the membrane pores 2 can also form electrolyte diffusion channels. After the electrolyte penetrates into the membrane pores 2, it can play a role in retaining electrolyte, avoiding problems such as lithium plating and electrolyte leakage caused by insufficient electrolyte, thus improving the service life of the current collector. In addition, the gradually increasing opening area and / or opening density, which is adapted to the current density distribution, can also improve the overcurrent capacity and reduce the internal resistance of the battery cell.

[0043] Specifically, the base film 1 mainly serves a load-bearing function, and its thickness direction is as follows: Figure 1 As shown by arrow H in the figure, the length direction is as follows Figure 2 As shown by arrow L in the image, the width direction is as follows: Figure 2As indicated by arrow W, the metal layer 3 can be incorporated into the membrane pores 2 via magnetron sputtering or electroplating. The opening area and / or opening density of the membrane pores 2 in the second opening region 103 is greater than that in the transition region 102, and the opening area and / or opening density of the membrane pores 2 in the transition region 102 is greater than that in the first opening region 101. The second opening region 103 is located close to the electrode tab, meaning that the closer the current collector is to the electrode tab, the larger the opening area and / or opening density of its membrane pores 2, thus matching the current density distribution. Furthermore, the metal layers 3 on both sides of the base film 1 can be welded and fixed at the membrane pores 2 in the second opening region 103, forming a conductive path and reducing internal resistance.

[0044] It should be noted that this embodiment of the invention does not limit the materials of the base film 1 and the metal layer 3, and any existing material can be selected as needed. For example, the base film 1 can be a PET (polyethylene terephthalate) film or a PP (polypropylene) film. The metal layer 3 can be a copper layer or an aluminum layer.

[0045] In one embodiment, such as Figure 1 and Figure 2 As shown, the membrane pore 2 includes a plurality of first sub-pores 201 disposed in the first opening region 101. The first sub-pores 201 are circular holes for easy processing. The diameter of the first sub-pores 201 is Φ1, and the ratio of the total opening area of ​​each first sub-pore 201 to the area of ​​the first opening region 101 is P1, satisfying 2μm≤Φ1≤20μm and 5%≤P1≤15%. By controlling the diameter of the first sub-pores 201 and the ratio of the total opening area of ​​each first sub-pore 201 to the area of ​​the first opening region 101, it can be ensured that the metal layer 3 partially penetrates into the first sub-pores 201 in the first opening region 101, thereby improving the adhesion between the metal layer 3 and the base film 1.

[0046] For example, in this embodiment of the present invention, the diameters of the first sub-holes 201 in the first opening region 101 can be the same. For instance, the diameter Φ1 of the first sub-holes 201 can be 2μm, 5μm, 10μm, 15μm, 20μm, etc. The ratio P1 of the total opening area of ​​the first sub-holes 201 to the area of ​​the first opening region 101 can be 5%, 10%, 15%, etc.

[0047] Furthermore, in one embodiment, the first sub-hole 201 is a through hole or a blind hole, and the metal layer 3 partially penetrates into the first sub-hole 201. Setting the first sub-hole 201 as a through hole or a blind hole facilitates the penetration of the metal layer 3 into the first sub-hole 201, thereby increasing the bonding area between the metal layer 3 and the base film 1 and improving the bonding strength between the metal layer 3 and the base film 1.

[0048] In one embodiment, such as Figure 1 and Figure 2As shown, the membrane aperture 2 includes a plurality of second sub-apertures 202 disposed in the transition region 102. Along the length direction, the opening area and number of openings of the plurality of second sub-apertures 202 gradually increase from the first opening region 101 to the second opening region 103. That is, the opening area and number of openings of the second sub-apertures 202 closer to the first opening region 101 are smaller than the opening area and number of openings closer to the second opening region 103. The transition region 102 can play a buffering role to prevent uneven stretching during rolling and thus prevent wrinkles on the electrode sheet.

[0049] Furthermore, in one embodiment, the second sub-hole 202 is a circular hole with a diameter of Φ2. The ratio of the total opening area of ​​each second sub-hole 202 to the area of ​​the transition region 102 is P2, satisfying 10μm≤Φ2≤40μm and 10%≤P2≤30%. By controlling the diameter of the second sub-hole 202 and the ratio of the total opening area of ​​each second sub-hole 202 to the area of ​​the transition region 102, it can be ensured that the transition region 102 provides a buffering effect.

[0050] For example, in this embodiment of the present invention, the diameter Φ2 of the second sub-hole 202 can be 10μm, 20μm, 30μm, 40μm, etc. The ratio P2 of the total opening area of ​​each second sub-hole 202 to the area of ​​the transition region 102 can be 10%, 20%, 30%, etc.

[0051] In addition, the second sub-hole 202 can be a through hole or a blind hole.

[0052] In one embodiment, such as Figure 1 and Figure 2 As shown, the membrane pore 2 includes multiple third sub-pores 203 disposed in the second opening region 103. The third sub-pores 203 are circular holes with a diameter of Φ3. The ratio of the total opening area of ​​each third sub-pore 203 to the area of ​​the second opening region 103 is P3, which satisfies 30μm≤Φ3≤100μm and 25%≤P3≤35%. By controlling the diameter of the third sub-pores 203 and the ratio of the total opening area of ​​each third sub-pore 203 to the area of ​​the second opening region 103, it can be ensured that the metal layers 3 on opposite sides of the base film 1 in the thickness direction are in contact and welded and fixed within the third sub-pores 203.

[0053] By way of example, in this embodiment of the present invention, the diameters of the third sub-holes 203 in the second opening region 103 can be the same. The diameter Φ3 of the third sub-hole 203 can be 30μm, 50μm, 80μm, 100μm, etc. The ratio P3 of the total opening area of ​​the third sub-holes 203 to the area of ​​the second opening region 103 can be 25%, 30%, 35%, etc.

[0054] Furthermore, in one embodiment, the third sub-hole 203 is a through-hole, in which two metal layers 3 located on opposite sides of the base film 1 in the thickness direction partially penetrate into and connect to the third sub-hole 203. By setting the third sub-hole 203 as a through-hole, the metal layers 3 on both sides of the base film 1 in the thickness direction are welded and fixed together through the third sub-hole 203 to form a conductive path, which can reduce the internal resistance.

[0055] Traditional current collectors made of composite foil have an insulating base film in the middle, which prevents different electrodes from conducting to each other, requiring additional bonding equipment to weld the electrodes together. This embodiment of the invention uses a third sub-hole 203 to weld the metal layers 3 on both sides of the base film 1 in the thickness direction to form a conductive path, eliminating the need for additional bonding of different electrodes, thereby improving electrode processing efficiency and reducing manufacturing costs.

[0056] In other embodiments, the shapes of the first sub-hole 201, the second sub-hole 202, and the third sub-hole 203 can be selected as conventional holes such as rectangular holes or elliptical holes, or unconventional holes as needed.

[0057] In one embodiment, the length of the first opening region 101 is L1, which satisfies 100mm≤L1≤1000mm.

[0058] And / or, the length of the transition region 102 is L2, which satisfies 5mm≤L2≤10mm.

[0059] And / or, the length of the second opening region 103 is L3, satisfying 10mm≤L3≤40mm.

[0060] By controlling the length of the first opening region 101, the length of the transition region 102, and the length of the second opening region 103, it can be ensured that the first opening region 101 has sufficient length to bond with the metal layer 3, the transition region 102 has sufficient length to provide buffer protection, and that the two metal layers 3 are welded and fixed in the second opening region 103 to form a conductive path.

[0061] For example, in this embodiment of the present invention, the length L1 of the first opening region 101 can be 100mm, 300mm, 500mm, 800mm, 1000mm, etc. The length L2 of the transition region 102 can be 5mm, 8mm, 10mm, etc. The length L3 of the second opening region 103 can be 10mm, 20mm, 30mm, 40mm, etc.

[0062] The preparation process of the current collector in this embodiment of the utility model is as follows:

[0063] The length L3 of the second aperture region 103 and the length L2 of the transition region 102 are designed to divide the second aperture region 103 and the transition region 102, with the remaining area serving as the first aperture region 101. The diameter and number of membrane pores 2 in the three regions are selected, and laser drilling is used. Metal layers 3 are connected to both sides of the base film 1 in the thickness direction by magnetron sputtering or electroplating to form a current collector.

[0064] For example, the length L3 of the second opening region 103 is 40 mm, the length L2 of the transition region 102 is 7 mm, and the length L1 of the first opening region 101 is 500 mm. The diameter Φ1 of the first sub-hole 201 of the first opening region 101 is 8 μm. The ratio P1 of the total area of ​​all first sub-holes 201 to the area of ​​the first opening region 101 is 10%. The diameter Φ2 of the second sub-holes 202 in the transition region 102 gradually increases from 10 μm to 40 μm. The ratio P2 of the total area of ​​all second sub-holes 202 to the area of ​​the transition region 102 is 20%. The diameter Φ3 of the third sub-hole 203 of the second opening region 103 is 50 μm. The ratio P3 of the total area of ​​all third sub-holes 203 to the area of ​​the second opening region 103 is 30%.

[0065] An active material layer (graphite) is coated onto the first opening region 101 and the transition region 102 of the current collector to obtain an electrode. After coating, the electrode is dried and rolled, and then assembled, formed, and aged to form a battery cell.

[0066] The internal resistance of the battery cell prepared in this embodiment is about 0.5mΩ. With an expansion space of 2%, the retention rate is about 80% after 1500 cycles at room temperature. Compared with the current collector made of traditional unperforated composite foil, the internal resistance of this embodiment is reduced by about 5% and the service life is increased by about 100%.

[0067] According to an embodiment of the present invention, in a second aspect, an electrode sheet is also provided, mainly comprising: an active material layer and a current collector, wherein the active material layer is coated on at least one side of the first opening region 101 and the transition region 102 in the thickness direction.

[0068] The electrode provided in this embodiment of the invention features membrane pores 2 with gradually increasing opening area and / or opening density in the first opening region 101, the transition region 102, and the second opening region 103. This allows the metal layer 3 to penetrate into the membrane pores 2, increasing the adhesion area between the metal layer 3 and the base film 1, thereby enhancing their adhesion strength. Furthermore, the membrane pores 2 also form electrolyte diffusion channels. After the electrolyte penetrates into the membrane pores 2, it can retain electrolyte, preventing problems such as lithium plating and electrolyte leakage caused by insufficient electrolyte, thus improving the service life of the current collector. In addition, the gradually increasing opening area and / or opening density, which is adapted to the current density distribution, can also improve the overcurrent capacity and reduce the internal resistance of the battery cell.

[0069] Specifically, the electrode includes a positive electrode and a negative electrode, wherein the negative electrode includes a negative current collector and a negative active material layer. The negative active material layer includes one or more of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material can be selected from one or more of elemental silicon, silicon oxide, and silicon-carbon composites. The tin-based material can be selected from one or more of elemental tin, tin oxide, and tin alloys. The metal layer 3 of the negative current collector can be made of copper foil. The positive electrode includes a positive current collector and a positive active material layer. The positive active material layer can include one or more of the following: lithium nickel oxide, lithium cobalt oxide, lithium titanium oxide, nickel cobalt multi-element oxide, lithium manganese oxide, lithium iron phosphorus oxide, etc. The metal layer 3 of the positive current collector can be made of aluminum foil.

[0070] According to an embodiment of the present invention, in a third aspect, a battery cell is also provided, comprising: at least one electrode.

[0071] The battery cell of this invention features membrane pores 2 with gradually increasing opening area and / or opening density in the first opening region 101, transition region 102, and second opening region 103. This allows the metal layer 3 to penetrate into the membrane pores 2, increasing the adhesion area between the metal layer 3 and the base film 1, thereby enhancing their bonding strength. Furthermore, the membrane pores 2 also form electrolyte diffusion channels. After the electrolyte penetrates into the membrane pores 2, it can retain electrolyte, preventing problems such as lithium plating and electrolyte leakage due to insufficient electrolyte, thus improving the service life of the current collector. In addition, the gradually increasing opening area and / or opening density, adapted to the current density distribution, can also improve the overcurrent capacity and reduce the internal resistance of the battery cell.

[0072] According to an embodiment of the present invention, in a fourth aspect, a battery pack is also provided, comprising: at least one battery cell.

[0073] The battery pack provided in this embodiment of the invention features membrane pores 2 with gradually increasing opening area and / or opening density in the first opening region 101, transition region 102, and second opening region 103. This allows the metal layer 3 to penetrate into the membrane pores 2, increasing the adhesion area between the metal layer 3 and the base film 1, thereby enhancing their adhesion strength. Furthermore, the membrane pores 2 also form electrolyte diffusion channels. After the electrolyte penetrates into the membrane pores 2, it can retain electrolyte, preventing problems such as lithium plating and electrolyte leakage due to insufficient electrolyte, thus improving the service life of the current collector. In addition, the gradually increasing opening area and / or opening density, adapted to the current density distribution, can also improve the overcurrent capacity and reduce the internal resistance of the battery cell.

[0074] In a battery pack, there are usually multiple cells. These cells can be connected in series, parallel, or in a mixed manner and housed in a casing. A mixed connection refers to multiple cells that are connected in both series and parallel.

[0075] To achieve the basic functions of the battery pack, it may also include other structures, such as a busbar for electrical connection between multiple cells. Each cell can be a secondary or primary battery; it can also be a lithium-sulfur battery, sodium-ion battery, or magnesium-ion battery, but is not limited to these. The battery pack may be cylindrical, flat, cuboid, or other shapes.

[0076] It should be noted that other necessary modules or components included in the battery pack can be selected from any suitable existing structures. To clearly and concisely illustrate the technical solution provided in this embodiment, the above-mentioned parts will not be repeated here, and the accompanying drawings have also been simplified accordingly. However, it should be understood that the scope of the embodiments of this utility model is not limited thereto.

[0077] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A current collector characterized by comprising: include: The base film has a plurality of membrane pores extending along the thickness direction on its surface. The base film is divided into a first opening region, a transition region and a second opening region along its length direction. The opening area and / or opening density of the plurality of membrane pores gradually increase in the first opening region, the transition region and the second opening region. Metal layers are disposed on opposite sides of the base film in the thickness direction.

2. The current collector of claim 1, wherein The membrane pores include a plurality of first sub-pores disposed in the first opening region. The first sub-pores are circular holes with a diameter of Φ1. The ratio of the total opening area of ​​each first sub-pore to the area of ​​the first opening region is P1, which satisfies 2μm≤Φ1≤20μm and 5%≤P1≤15%. The first sub-hole is a through hole or a blind hole, and the metal layer partially penetrates into the first sub-hole.

3. The current collector of claim 1, wherein The membrane pores include a plurality of second sub-pores disposed in the transition region. Along the length direction, the opening area and the number of openings of the plurality of second sub-pores gradually increase from the first opening region to the second opening region.

4. The current collector of claim 3, wherein The second sub-hole is a circular hole with a diameter of Φ2. The ratio of the total area of ​​the openings of all the second sub-holes to the area of ​​the transition region is P2, which satisfies 10μm≤Φ2≤40μm and 10%≤P2≤30%.

5. The current collector according to claim 1, characterized in that, The membrane pores include a plurality of third sub-pores disposed in the second opening region. The third sub-pores are circular holes with a diameter of Φ3. The ratio of the total opening area of ​​each third sub-pore to the area of ​​the second opening region is P3, which satisfies 30μm≤Φ3≤100μm and 25%≤P3≤35%.

6. The current collector according to claim 5, characterized in that, The third sub-hole is a through hole, in which two metal layers located on opposite sides of the base film thickness direction partially penetrate and connect to each other.

7. The current collector according to any one of claims 1 to 6, characterized in that, The length of the first opening area is L1, which satisfies 100mm≤L1≤1000mm; And / or, the length of the transition region is L2, satisfying 5mm≤L2≤10mm; And / or, the length of the second opening area is L3, satisfying 10mm≤L3≤40mm.

8. An electrode sheet, characterized in that, include: Active material layer; According to any one of claims 1 to 7, the active material layer is coated on at least one side of the first opening region and the transition region in the thickness direction.

9. A battery cell, characterized in that, include: At least one electrode as described in claim 8.

10. A battery pack, characterized in that, include: At least one battery cell as described in claim 9.

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