Current collector and manufacturing method thereof, pole piece, secondary battery and electric device

Abstract

The invention relates to the technical field of batteries, and relates to a current collector and a manufacturing method thereof, a pole piece, a secondary battery and an electric device, the secondary battery comprises the pole piece, the pole piece comprises the current collector and an electrode active material layer arranged on at least one surface of the current collector; the current collector comprises a supporting layer and conductive layers arranged on the two surfaces of the supporting layer, and the supporting layer comprises a porous material; compared with a traditional metal current collector, through the three-layer composite structure of the conducting layer, the supporting layer comprising the porous material and the conducting layer, electrolyte can be easily absorbed, the liquid phase transmission path is increased, the liquid phase transmission path is shortened, the liquid phase diffusion impedance is reduced, and the liquid phase transmission efficiency is improved, so that the infiltration capacity of a pole piece is improved; the cycle performance of the battery is improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a current collector and its manufacturing method, an electrode, a secondary battery, and an electrical device. Background Technology

[0002] Due to their advantages such as high energy density, long cycle life, and low self-discharge rate, rechargeable batteries are increasingly being used in various electric vehicles and consumer electronics products. Furthermore, as the application scope of rechargeable batteries expands, the requirements for their cycle performance are also becoming increasingly stringent.

[0003] In secondary batteries, due to the frequent charging and discharging processes and the pursuit of higher energy density and longer cycle life, the chemical reactions inside the battery are more complex and intense. This places higher demands on the performance of current collectors. Therefore, developing new current collectors with superior performance has become one of the directions of particular interest to those skilled in the art. Summary of the Invention

[0004] The main objective of this invention is to provide a current collector and its manufacturing method, an electrode, a secondary battery, and an electrical device, with the aim of improving the cycle performance of the battery.

[0005] To achieve the above objectives, a first aspect of the present invention provides a secondary battery, including an electrode sheet, the electrode sheet including a current collector and an electrode active material layer disposed on at least one surface of the current collector; the current collector including a support layer and a conductive layer disposed on both surfaces of the support layer, wherein the support layer includes a porous material.

[0006] Porous materials are materials with a network structure consisting of interconnected or closed pores. They possess advantages such as low relative density, high specific strength, high specific surface area, light weight, and good permeability. Therefore, porous materials can easily absorb electrolyte, increasing or shortening the liquid phase transport path, reducing liquid phase diffusion resistance, and improving liquid phase diffusion efficiency, thereby enhancing the wetting ability of the electrode. In the secondary battery of this invention, the current collector of the electrode adopts a three-layer composite structure: a conductive layer, a support layer including a porous material, and a conductive layer. This structure allows for easier absorption of electrolyte, increasing or shortening the liquid phase transport path, reducing liquid phase diffusion resistance, and improving liquid phase transport efficiency, thus enhancing the wetting ability of the electrode and improving the cycle performance of the battery.

[0007] Optionally, the pore size of the porous material is 0.1 μm-5 μm; and / or, the specific surface area of ​​the porous material is 10 m². 2 / g-60m 2 / g; and / or, the tortuosity of the pore structure of the porous material is 50%-80%.

[0008] This invention selects porous materials with suitable pore sizes, resulting in high utilization of the pore structure. This enhances the capillary action for liquid absorption inside the battery without affecting the particle count of the porous material. The porous material utilizes a large specific surface area and suitable pore structure tortuosity, exhibiting good liquid absorption performance, a short absorption path, and a high absorption rate.

[0009] Optionally, the porous material includes at least one of covalent organic framework materials and their derivatives, metal-organic framework compound materials and their derivatives, fiber materials, carbon cloth materials, and carbon nanotubes.

[0010] The porous material used in this invention has good liquid storage and air absorption properties, and easily absorbs electrolyte, which is beneficial to improving the wettability of the electrode.

[0011] Optionally, the support layer further includes a substrate, and the porous material is composited onto the substrate.

[0012] In this invention, porous materials are coated on the surface of a substrate to form a support layer, or porous materials are mixed and combined with substrate materials to form a sheet-like support layer. This not only achieves the effects of liquid storage and air absorption, but also ensures the structural strength of the support layer.

[0013] Optionally, the porosity of the current collector is 30%-65%.

[0014] The present invention selects a current collector with suitable porosity that has excellent liquid and gas absorption properties, thereby improving the wetting ability of the electrode and the overall structural strength of the current collector.

[0015] Optionally, the porous material accounts for 1%-100% of the mass of the support layer; and / or, the thickness of the support layer is 0.5μm-15μm; and / or, the thickness of the conductive layer is 0.5μm-15μm.

[0016] In this invention, the porous material selected with the aforementioned suitable mass ratio exhibits excellent liquid absorption and gas storage properties. The support layer, with the aforementioned suitable thickness, can better absorb the electrolyte, further enhancing its wetting ability. The conductive layer, with the aforementioned suitable thickness, allows the battery cell to possess both good conductivity and high energy density.

[0017] Optionally, the conductive layer has a first hole; and / or, the conductive layer has a first groove; and / or, the conductive layer includes a plurality of conductive portions, which are spaced apart on at least one surface of the support layer.

[0018] In this invention, the conductive layer is provided with openings, grooves, or adopts a split structure to expose part of the surface of the support layer and form a transmission channel. In this way, the liquid phase (i.e., electrolyte) can be transmitted through the transmission channel, thereby increasing the liquid phase transmission path, shortening the liquid phase transmission path, reducing the liquid phase diffusion resistance, increasing the liquid phase transmission rate, and further improving the wetting ability of the electrode.

[0019] Optionally, the support layer is configured as multiple layers, with adjacent support layers being compositely connected, and the conductive layer is disposed on the outer surface of the outermost support layer.

[0020] The present invention provides a multi-layer support layer, which can not only further improve the wetting ability of the electrode, but also improve the toughness of the current collector and reduce the risk of breakage in the later stages of cell cycling.

[0021] Optionally, the support layer has a second hole; and / or, the support layer has a second notch.

[0022] The support layer of the present invention is provided with a second hole or a second groove, through which the liquid phase (i.e., electrolyte) can be transported, thereby increasing the liquid phase transport path, shortening the liquid phase transport path, improving the liquid phase transport rate, reducing the liquid phase diffusion resistance, and further improving the wetting ability of the electrode.

[0023] Optionally, a second aspect of the present invention also provides a current collector, the current collector comprising a support layer and conductive layers disposed on both surfaces of the support layer, wherein the support layer comprises a porous material.

[0024] Optionally, the support layer further includes a substrate, to which the porous material is compositely connected.

[0025] Optionally, the porosity of the current collector is 1%-80%.

[0026] The present invention selects a current collector with suitable porosity that has excellent liquid and gas absorption properties, thereby improving the wetting ability of the electrode and the overall structural strength of the current collector.

[0027] Optionally, the porosity of the current collector is 30%-65%.

[0028] Optionally, the conductive layer has a first hole; and / or, the conductive layer has a first groove; and / or, the conductive layer includes a plurality of conductive portions, which are spaced apart on one surface of the support layer.

[0029] Optionally, the support layer is configured as multiple layers, with adjacent support layers being compositely connected, and the conductive layer being connected to the surface of the outermost support layer; and / or, the support layer has a second hole; and / or, the support layer has a second groove.

[0030] A third aspect of the present invention also provides a method for manufacturing a current collector, comprising the following steps:

[0031] Two conductive layers and a support layer are fabricated using conductive and porous materials, respectively, and the two opposing surfaces of the two conductive layers and the support layer are then joined together to obtain the current collector.

[0032] Compared to traditional metal current collectors, this invention uses a porous material to make a support layer, and then combines the two opposing surfaces of the support layer with two conductive layers to create a three-layer composite current collector, which is simpler to operate.

[0033] Optionally, the step of fabricating a conductive layer and a support layer using conductive material and porous material respectively, and then bonding the conductive layer and the support layer together to obtain the current collector includes:

[0034] A support layer is obtained by combining porous materials with a substrate.

[0035] This invention uses a composite of porous and insulating materials to create the support layer, which not only achieves the effects of liquid storage and air absorption, but also ensures the structural strength of the support layer.

[0036] Optionally, the step of fabricating the conductive layer and the support layer using conductive material and porous material respectively, and then bonding the conductive layer and the support layer together to obtain the current collector, further includes:

[0037] Create openings in the conductive layer; and / or,

[0038] Score the conductive layer.

[0039] The present invention makes openings or grooves in the conductive layer to expose part of the surface of the support layer and form a transmission channel. In this way, the liquid phase (i.e., electrolyte) can be transmitted through the transmission channel, thereby increasing the liquid phase transmission path, shortening the liquid phase transmission path, reducing the liquid phase diffusion resistance, increasing the liquid phase transmission rate, and further improving the wetting ability of the electrode.

[0040] Optionally, the step of fabricating the conductive layer and the support layer using conductive material and porous material respectively, and then bonding the conductive layer and the support layer together to obtain the current collector, further includes:

[0041] A conductive layer is made of conductive material, and multiple support layers are made of porous material.

[0042] Multiple support layers are stacked and connected, and a conductive layer is compositely connected to the outermost support layer to obtain the current collector.

[0043] The invention creates a multi-layer support layer, which can not only further improve the wettability of the electrode sheets, but also improve the toughness of the current collector and reduce the risk of breakage in the later stages of cell cycling.

[0044] Optionally, the step of fabricating the conductive layer and the support layer using conductive material and porous material respectively, and then bonding the conductive layer and the support layer together to obtain the current collector, further includes:

[0045] Make openings in the support layer; and / or,

[0046] Score the support layer.

[0047] The present invention makes openings or grooves in the support layer to further increase the liquid phase transport path, shorten the liquid phase transport path, improve the liquid phase transport rate, and reduce the liquid phase diffusion resistance, thereby further improving the wetting ability of the electrode.

[0048] A fourth aspect of the present invention also provides an electrode sheet, the electrode sheet comprising an electrode active material layer and a current collector provided in the first aspect or a current collector manufactured by the method of manufacturing the current collector provided in the second aspect, wherein the electrode active material layer is disposed on the side of the current collector where the conductive layer is away from the support layer.

[0049] At least one of the positive electrode and the negative electrode includes a current collector manufactured by the method for manufacturing the current collector provided in the second aspect; or,

[0050] At least one of the positive electrode and the negative electrode is an electrode provided by the fourth aspect.

[0051] The fifth aspect of the present invention also provides an electrical device, the electrical device comprising the secondary battery provided in the fourth aspect.

[0052] The secondary battery provided by this invention includes an electrode sheet, which comprises a current collector and an electrode active material layer disposed on at least one surface of the current collector. The current collector comprises a support layer and conductive layers disposed on both surfaces of the support layer, wherein the support layer comprises a porous material. Compared with traditional metal current collectors, this invention adopts a three-layer composite structure of a conductive layer-a support layer comprising porous material-a conductive layer, which can more easily absorb electrolyte, increase the liquid phase transport path, shorten the liquid phase transport path, reduce the liquid phase diffusion resistance, and improve the liquid phase transport efficiency, thereby improving the wettability of the electrode sheet and improving the cycle performance of the battery. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0054] Figure 1This is a cross-sectional structural schematic diagram of an embodiment of the electrode provided by the present invention;

[0055] Figure 2 This is a schematic cross-sectional view of another embodiment of the electrode provided by the present invention;

[0056] Figure 3 A cross-sectional structural schematic diagram of another embodiment of the electrode provided by the present invention;

[0057] Figure 4 This is a cross-sectional structural schematic diagram of another embodiment of the electrode provided by the present invention;

[0058] Figure 5 for Figure 1 A schematic diagram of the support layer for the central fluid collector from another perspective;

[0059] Figure 6 for Figure 3 A schematic diagram of the support layer for the central fluid collector from another perspective;

[0060] Figure 7 This is a schematic diagram comparing the wetting rates of the battery cells obtained in Example 1 and Comparative Example 1 of the present invention.

[0061] Explanation of icon numbers:

[0062] 100. Electrode; 1. Conductive layer; 11. First hole; 12. First notch; 2. Support layer; 21. Porous material layer; 22. Substrate; 23. Second hole; 24. Second notch; 3. Electrode active material layer.

[0063] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0064] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0065] The current collector, its manufacturing method, electrode, and secondary battery of the present invention are disclosed in detail below with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the invention and are not intended to limit the subject matter of the claims.

[0066] The "range" disclosed in this invention is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is understood that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this invention, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0067] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0068] Unless otherwise specified, all technical features and optional technical features of this invention can be combined to form new technical solutions.

[0069] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0070] In recent years, with the increasingly wide application of lithium-ion batteries, they have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power plants, as well as in many fields such as power tools, electric bicycles, electric motorcycles, electric cars, military equipment, and aerospace.

[0071] With the rapid development of the lithium battery industry, the energy density of power cells is required to be increasingly higher. Consequently, cells are becoming thicker and taller, and the weight of electrode compaction and coating is also increasing. Among these challenges, the wetting problem has become a bottleneck for cell upgrades and urgently needs to be addressed. On the one hand, due to the increased thickness of the electrodes, the electrolyte penetration process takes longer, making it difficult to wet the electrodes. On the other hand, the increased height and thickness of the cells increase the path and difficulty of electrolyte creep, making it more difficult to complete wetting within the same time frame. Furthermore, as the electrolyte is consumed in later cycles, the liquid level gradually decreases, making it even more difficult to wet the top of the cell. This leads to lithium plating problems due to poor wetting in the early stages of charging or in the later stages of cycling, ultimately causing cycling issues in lithium batteries.

[0072] Based on this, the first aspect of the present invention provides a secondary battery, wherein, as an example, the secondary battery is a lithium-ion battery.

[0073] The secondary battery provided by the present invention includes an electrode 100, the electrode 100 including a current collector and an electrode active material layer 3 disposed on at least one surface of the current collector; the current collector includes a support layer 2 and a conductive layer 1 disposed on both surfaces of the support layer 2, wherein the support layer 2 includes a porous material.

[0074] Please see Figures 1 to 4 In one embodiment, the current collector includes a support layer 2 and two conductive layers 1. The support layer 2 includes a porous material, and the two conductive layers 1 are respectively connected to two opposite surfaces of the support layer 2.

[0075] Porous materials are materials with a network structure composed of interconnected or closed pores. They possess advantages such as low relative density, high specific strength, high specific surface area, light weight, and good permeability. Therefore, porous materials can easily absorb electrolyte, increasing or shortening the liquid phase transport path, reducing liquid phase diffusion resistance, and improving liquid phase diffusion efficiency, thereby enhancing the wetting ability of the electrode 100, including the current collector. Furthermore, compared to traditional metal current collectors, this invention employs a three-layer composite structure of conductive layer 1-support layer 2-conductive layer 1, which helps reduce the weight of the current collector and improve the energy density of the battery. In addition, porous materials also have good gas storage performance, capable of absorbing gases generated by the battery cell, including the current collector, during cycling, solving the problem of electrical swelling. They can also absorb gases generated during the aging process of the battery cell, including the current collector, solving the problem of bubbly purple spots, black spots, and lithium plating at the full-charge interface caused by the inability to vent gas due to sealing, thus improving the cycle performance and safety of the battery cell and extending its service life.

[0076] The conductive layer 1 is made of conductive material. For example, the conductive layer 1 can be copper foil, aluminum foil, or other metal foil. Of course, the conductive layer 1 can also be made by spraying, deposition, or other reasonable methods using conductive material, or by electroplating, electrostatic adsorption, chemical etching, or other methods.

[0077] Compared to traditional metal current collectors, the current collector of the present invention adopts a three-layer composite structure of conductive layer 1, support layer 2 including porous material, and conductive layer 1. This structure can more easily absorb electrolyte, increase and shorten the liquid phase transport path, reduce liquid phase diffusion resistance, and improve liquid phase diffusion efficiency. This improves the wetting ability of the electrode 100, enhances the cycle performance of the battery, and extends the battery's service life.

[0078] Furthermore, the current collector of the present invention adopts a three-layer composite structure of conductive layer 1-support layer 2-conductive layer 1, which effectively increases the strength of the current collector, solves the problem of corner breakage of the winding structure after electrode circulation, and can also reduce costs. Compared with traditional metal current collectors, its cost can be reduced by 20%.

[0079] It should be noted that the support layer 2 can be made of pure porous material into a sheet structure, or it can be made of porous material and other materials after being processed into a sheet structure, or it can be made on the surface of the substrate 22 by spraying, deposition or other reasonable methods. No limitation is made here.

[0080] In some embodiments, the pore size of the porous material is 0.1 μm-5 μm (e.g., 0.1 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, and any range between two endpoints). This results in a high utilization rate of the pore structure, which is beneficial for enhancing capillary action within the liquid absorption process without affecting the number of particles in the porous material. As an example, the pore size of the porous material is 1 μm-2 μm, 2 μm-3 μm, or 3 μm-4 μm. This results in a high utilization rate of the pore structure and facilitates the fabrication of the support layer 2.

[0081] In some embodiments, the specific surface area of ​​the porous material is 10 m². 2 / g-60m 2 / g (e.g., 10m) 2 / g、20m 2 / g、30m 2 / g、40m 2 / g, 50m 2 / g、60m 2 / g and the range between any two endpoints), specific surface area refers to the surface area per unit mass. A specific surface area within the aforementioned suitable range exhibits better liquid and gas absorption, thereby effectively improving the wetting ability of electrode 100. As an example, the specific surface area of ​​the porous material is 20m². 2 / g-30m 2 / g、30m 2 / g-40m 2 / g or 40m 2 / g-50m 2 / g, thus having good liquid and gas absorption effects, and easy to process to obtain support layer 2.

[0082] In some embodiments, the tortuosity of the porous material's pore structure is 50%-80% (e.g., 50%, 60%, 70%, 80%, and any range between two endpoints). Pore structure tortuosity refers to the degree of curvature of the pore structure. The tortuosity of the porous material's pore structure should be appropriately selected to ensure a shorter liquid absorption path and a higher liquid absorption rate. If the tortuosity is greater than 80%, it indicates that the pore structure is too curved, resulting in a longer liquid absorption path and affecting the liquid absorption rate.

[0083] In some embodiments, porous materials include at least one of covalent organic framework materials and their derivatives, metal-organic framework compound materials and their derivatives, fiber materials, carbon cloth materials, and carbon nanotubes.

[0084] Covalent organic frameworks (COFs) are porous framework materials with periodic structures. They are good liquid storage and gas absorption materials, easily absorb electrolyte, and are beneficial to improving the wetting ability of electrode 100.

[0085] Derivatives of covalent organic frameworks (COFs) refer to functional groups or substances synthesized from COFs. Examples of COF derivatives include, but are not limited to, COF-OH, COF-COOH, COF-COH, COF-Li, COF-C2H2, COF-C2H4, and COF-COCH3. These COF derivatives exhibit good moisture and gas absorption properties. They can absorb electrolytes, improving wettability, and also absorb gases generated during cell cycling, including those from the current collector, thus addressing the issue of electrical swelling. Furthermore, they can absorb gases generated during cell aging, including those from the current collector, resolving issues such as bubbly purple or black spots and lithium plating at the full-charge interface due to the inability to vent gas from the cell's sealing. This improves the cell's cycle performance and safety, extending its lifespan.

[0086] Metal-organic frameworks (MOFs) are porous materials with topological structures formed by the self-assembly of metal ions and organic ligands. They are good liquid storage and gas absorption materials, easily absorb electrolyte, and are beneficial to improving the wettability of electrode 100.

[0087] Derivatives of metal-organic framework (MOF) materials refer to functional groups or substances synthesized from MOFs. Examples of MOF derivatives include, but are not limited to, MOF-Na, MOF-K, MOF-74, MOF-Cu, IRMOF series, ZIF series, PCN series, MIL series, HKUST series, and UIO series. These MOF derivatives possess unique porous structures, high specific surface areas, excellent chemical properties and formation stability, and unique selectivity. This allows them to interact strongly with or react chemically with gases, resulting in strong gas absorption capabilities. They can absorb gases generated during battery cell cycling, addressing the issue of electrical swelling. They can also absorb gases generated during battery cell aging, resolving issues such as bubble-like purple spots, black spots, and lithium plating at the full charge interface due to the inability to vent gas from sealed cells, thus improving battery cell performance and safety.

[0088] As an example, MOF materials and their derivatives are synthesized with micron-sized molecules. The particle size D50 of the synthesized particles is 10-200 μm. The support layer 2 made in this way has a high specific surface area and strong liquid and gas absorption capacity.

[0089] Fiber materials include natural fibers, chemical fibers, and high-performance fibers. Natural fibers include, but are not limited to, cotton fibers and asbestos; chemical fibers include, but are not limited to, polyester, polyacrylonitrile fibers, glass fibers, metal fibers, ceramic fibers, and carbon fibers; and high-performance fibers include, but are not limited to, aramid fibers, ultra-high molecular weight polyethylene fibers, polyimide fibers, and polyphenylene sulfide fibers. Fiber materials are also good liquid storage and gas absorption materials, easily absorbing electrolyte, which is beneficial for improving the wetting ability of electrode 100.

[0090] Carbon cloth material, short for carbon fiber cloth, is also a good liquid storage and gas absorption material. It easily absorbs electrolyte, which is beneficial to improving the wetting ability of electrode 100.

[0091] Carbon nanotubes, as one-dimensional nanomaterials, are lightweight and are a good material for storing liquids and absorbing gases. They easily absorb electrolytes, which helps to improve the wetting ability of electrode 100.

[0092] In some embodiments of the present invention, the support layer 2 further includes a substrate 22, to which a porous material is composited. Specifically, the porous material is coated on the surface of the substrate 22 to form the support layer 2, or the porous material is first doped and composited with the material of the substrate 22 before forming the support layer; this is not limited here.

[0093] As an example, a porous material is coated onto the surface of the substrate 22 to form the support layer 2. This ensures the structural strength of the support layer 2 while also achieving the effect of liquid absorption and gas storage. Experimental testing shows that coating with 1 wt% porous material can store 10 mL / m³ of gas. 2 The wetting rate can be increased by 5%. With the increase of coating amount, the air absorption capacity and wetting efficiency are significantly improved. When the material of the support layer 2 is 100wt% porous material (that is, all of it is porous material), the air absorption rate reaches 150mL / m. 2 The wetting efficiency can be improved by 90%.

[0094] It should be noted that the porous material can be uniformly applied to the entire surface of the substrate 22, or it can be applied intermittently to a portion of the surface of the substrate 22. For example, the applied porous material may have a linear, spiral, S-shaped, Z-shaped, or dotted structure.

[0095] Optionally, the material of the substrate 22 is selected from at least one of insulating polymer materials, insulating polymer composite materials, conductive polymer materials, and conductive polymer composite materials.

[0096] As examples, substrate 22 includes, but is not limited to, polyethylene terephthalate (PET), polypropylene (PP), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE). Using the aforementioned substrate 22 ensures that the support layer 2 has good structural strength, thereby guaranteeing good overall structural strength of the current collector.

[0097] In this invention, the support layer 2 can be made of pure porous material, enabling rapid liquid absorption and gas storage. Specifically, the porous material can be directly processed into a sheet structure, or it can be coated using methods such as extrusion coating, transfer coating, or spray coating. Alternatively, the support layer 2 can be obtained by combining a porous material with the substrate 22, which not only enables liquid absorption and gas storage but also ensures good structural strength of the support layer 2.

[0098] In some embodiments, the porosity of the current collector is 1%-80% (e.g., 1%, 10%, 30%, 50%, 80%, and any range between two endpoints). Selecting a current collector with suitable porosity provides excellent liquid and gas absorption properties, resulting in better wettability of the electrode 100 and better overall structural strength of the current collector. Preferably, the porosity of the current collector is 30%-65% (e.g., 30%, 40%, 50%, 60%, 65%, and any range between two endpoints). If the porosity of the current collector is less than 30%, although it can improve the wettability of the electrode 100, it is not suitable for specific battery systems requiring high electrolyte wettability and high active material loading. If the porosity of the current collector is greater than 65%, it can lead to decreased conductivity and insufficient mechanical strength, thereby affecting the battery's lifespan.

[0099] The present invention can adjust the porosity of the current collector by controlling the proportion of porous material in the support layer 2, the thickness of the support layer 2, the openings or grooves in the conductive layer 1, and the openings or grooves in the support layer 2.

[0100] In some embodiments, the mass of the porous material accounts for 1%-100% of the mass of the support layer 2 (e.g., 1%, 10%, 50%, 100%, and any range between two endpoints). If the mass of the porous material is less than 100%, the support layer 2 is made of a composite of the porous material and the substrate 22; if the mass of the porous material accounts for 100% of the mass of the support layer 2, that is, the support layer 2 is entirely made of porous material, it has excellent liquid absorption and gas storage performance. The above-mentioned suitable range of the porous material proportion can ensure that the support layer 2 has good liquid absorption and gas storage performance, thereby improving the wetting ability of the electrode 100.

[0101] In some embodiments, the thickness of the support layer 2 is 0.5μm-15μm (e.g., 0.5μm, 1μm, 5μm, 10μm, 15μm, and any range between the two endpoints). Using a support layer 2 with the above thickness range can better absorb electrolyte and further improve wetting ability. If the thickness is less than 0.5μm, there will be insufficient current collector strength, and the risk of membrane cracking and band breakage during the preparation of electrode 100 samples. At the same time, the composite yield is also low, resulting in less porous coating and lower wetting and gas absorption effects. If the thickness is greater than 15μm, the current collector thickness will be too thick, the volumetric energy density of the cell will decrease, the competitiveness of the cell will decrease, and it will also affect the amount of porous material added, which will have a certain impact on cell wetting and gas absorption.

[0102] In some embodiments, the thickness of the conductive layer 1 is 0.5μm-15μm (e.g., 0.5μm, 1μm, 5μm, 10μm, 15μm, and any range between the two endpoints). Selecting a conductive layer 1 within the above thickness range allows the battery cell to have both good conductivity and high energy density. If the thickness is less than 0.5μm, it will affect current conduction. Insufficient current conduction in some areas will lead to excessive local heat generation, potentially causing thermal runaway of the battery cell. It may also cause uneven current density distribution, lithium plating, and the formation of lithium dendrites, leading to abnormal self-discharge or thermal runaway of the battery cell. If the thickness is greater than 15μm, the proportion of active material on the electrode will be too small, reducing the energy density of the battery cell and affecting its competitiveness. At the same time, the increased current collector thickness requires higher welding power, which may result in weak electrode tab welding, burn-through, or incomplete welding, affecting the battery cell's power output.

[0103] In some embodiments, the conductive layer 1 has a first hole 11. The first hole 11 can be a through hole, that is, penetrating both opposite surfaces of the conductive layer 11. In this case, the liquid phase (i.e., electrolyte) can be transported through the conductive layer 11 via the first hole 11. Alternatively, the first hole 11 can be a blind hole, that is, formed on one surface of the conductive layer 11 and not penetrating the other surface. In this case, the liquid phase (i.e., electrolyte) can be transported to the first hole 11 and transported out via the end face of the current collector. Both of the above can increase the liquid phase transport path, thereby improving the wetting ability of the electrode 100.

[0104] Please refer to it again. Figure 1 and Figure 2 In one embodiment, the first hole 11 penetrates the two opposite surfaces of the conductive layer 1. In this way, the liquid phase (i.e., electrolyte) can be transported through the first hole 11 through the conductive layer 1, increasing the liquid phase transport path, shortening the liquid phase transport path, reducing the liquid phase diffusion resistance, increasing the liquid phase transport rate, and further improving the wetting ability of the electrode 100.

[0105] It should be noted that the shape of the first hole 11 can be circular, square, oval, triangular or other reasonable shape, and is not limited here.

[0106] The size of the first hole 11 is determined according to the actual situation. As an example, the first hole 11 is a circular hole with an inner diameter of 1μm-50μm (e.g., 1μm, 10μm, 20μm, 30μm, 40μm, 50μm, and any range between the two endpoints). This ensures that the liquid absorbed by the support layer 2 can be quickly transferred to the electrode active material, accelerating the wetting efficiency of the electrode active material. At the same time, the first hole 11 provides a transport path for the generated gas and absorbs the gas. If the inner diameter is less than 1μm, it is not conducive to liquid phase transport, reducing the cell wetting effect and gas absorption effect. If the inner diameter is greater than 50μm, the strength of the support layer 2 is difficult to guarantee, and there is a risk of active material leakage, strip breakage during the cold pressing process of the electrode sheet, and cell breakage in the later stages of cell cycling.

[0107] In order to further increase the liquid phase transport path, shorten the liquid phase transport path, reduce the liquid phase diffusion resistance, and thus further improve the wetting ability of the electrode 100, in an optional embodiment, the first hole 11 is a through hole and multiple holes are opened, with multiple first holes 11 distributed at intervals. As an example, multiple first holes 11 are evenly distributed in an array, which is conducive to more uniform liquid phase transport, relatively small liquid phase diffusion resistance, and also facilitates the opening operation of the first hole 11.

[0108] It should be noted that in embodiments where multiple first holes 11 are formed in the conductive layer 1, the size of the multiple first holes 11 may be the same or different, their shapes may be the same or different, and the spacing between two adjacent first holes 11 may be the same or different, and none of these are limited here.

[0109] Optionally, the exposed area of ​​the support layer 2 corresponding to the first hole 11 accounts for more than 1% of the total surface area of ​​the support layer 2. This can achieve good liquid absorption capacity while ensuring that the conductive layer 1 has sufficient strength and good electronic conductivity.

[0110] In some embodiments, the conductive layer 1 is provided with a first notch 12. The first notch 12 can penetrate both opposite surfaces of the conductive layer 11, in which case the liquid phase (i.e., electrolyte) can be transported through the conductive layer 11 via the first notch 12; of course, the first notch 12 can also be provided on one surface of the conductive layer 11 and not penetrate the other surface, in which case the liquid phase (i.e., electrolyte) can be transported to the first notch 12 and transported out via the end face of the current collector. All of the above can increase the liquid phase transport path, thereby improving the wetting ability of the electrode 100.

[0111] Please refer to it again. Figure 3 and Figure 4In some embodiments, the first notch 12 penetrates the two opposite surfaces of the conductive layer 11, so that the liquid phase (i.e., electrolyte) can be transported through the first notch 12, thereby increasing the liquid phase transport path, shortening the liquid phase transport path, reducing the liquid phase diffusion resistance, and further improving the wetting ability of the electrode 100.

[0112] It should be noted that the shape of the first notch 12 can be elongated, and its specific shape and size can be determined according to the actual situation, and are not limited here. As long as the exposed area of ​​the support layer 2 corresponding to the first notch 12 accounts for more than 1% of the total surface area of ​​the support layer 2, it is acceptable.

[0113] To further increase and shorten the liquid phase transport path and reduce the liquid phase diffusion resistance, thereby further improving the wetting ability of the electrode 100, in an optional embodiment, the first notch 12 penetrates the two opposite surfaces of the conductive layer 1 and is made in multiples, with the multiple first notches 12 distributed at intervals. As an example, the multiple first notches 12 are evenly distributed in an array, which is conducive to more uniform liquid phase transport, relatively small liquid phase diffusion resistance, and also facilitates the opening operation of the first notch 12.

[0114] It should be noted that in embodiments where multiple first notches 12 are formed in the conductive layer 1, the dimensions of the multiple first notches 12 may be the same or different, their shapes may be the same or different, and the spacing between two adjacent first notches 12 may be the same or different, and none of these are limited here.

[0115] Of course, in some other embodiments, the conductive layer 1 is simultaneously provided with a first notch 12 and a first hole 11 penetrating both surfaces. This can also increase the liquid phase transport path, shorten the liquid phase transport path, improve the liquid phase transport rate, and reduce the liquid phase diffusion resistance, thereby further improving the wetting ability of the electrode 100. The specific shape, size, and setting position of the first hole 11 and the first notch 12 can be reasonably adjusted according to the actual situation, as long as the exposed area of ​​the support layer 2 corresponding to the first notch 12 accounts for more than 1% of the total surface area of ​​the support layer 2.

[0116] In some embodiments, the conductive layer 1 includes a plurality of conductive portions, which are spaced apart on one surface of the support layer 2.

[0117] In this embodiment, the conductive layer 1 adopts a split structure, that is, it includes multiple conductive parts. The shape and size of the conductive parts are not limited here. The multiple conductive parts are distributed at intervals. The gap between two adjacent conductive parts can expose the corresponding part of the support layer 2. In this way, the liquid phase can be transported through the gap between two adjacent conductive parts, which can also increase the liquid phase transport path, shorten the liquid phase transport path, improve the liquid phase transport rate, reduce the liquid phase diffusion resistance, and further improve the wetting ability of the electrode 100 and improve the cycle performance of the battery.

[0118] It should be noted that the shapes and sizes of multiple conductive parts can be the same or different, and the spacing between two adjacent conductive parts can be the same or different; no limitation is made here.

[0119] In some embodiments, the support layer 2 has a second hole 23. The second hole 23 can be a through hole, that is, penetrating both opposite surfaces of the conductive layer 11. In this case, the liquid phase (i.e., electrolyte) can be transported through the conductive layer 11 via the second hole 23. Alternatively, the second hole 23 can be a blind hole, that is, formed on one surface of the conductive layer 11 and not penetrating the other surface. In this case, the liquid phase (i.e., electrolyte) can be transported to the second hole 23 and transported out via the end face of the current collector. Both of these methods can increase the liquid phase transport path, thereby improving the wetting ability of the electrode 100.

[0120] Please refer to it again. Figure 1 , Figure 2 and Figure 5 In one embodiment, the second hole 23 penetrates the two opposite surfaces of the conductive layer 1, so that the liquid phase (i.e., electrolyte) can be transported through the second hole 23, thereby increasing the liquid phase transport path, shortening the liquid phase transport path, reducing the liquid phase diffusion resistance, and further improving the wetting ability of the electrode 100.

[0121] It should be noted that the shape of the second hole 23 can be circular, square, oval, triangular or other reasonable shape, and is not limited here.

[0122] The size of the second hole 23 depends on the actual situation. For example, the second hole 23 is a circular hole, and the inner diameter of the first hole 11 is 1-50μm (e.g., 1μm, 10μm, 20μm, 30μm, 40μm, 50μm and any range between the two endpoints). This allows the electrolyte and gas to pass through fully, improving the wetting efficiency and gas absorption capacity of the cell. If the inner diameter is less than 1μm, it is not conducive to liquid phase transport, gas transport and absorption. If the inner diameter is greater than 50μm, the strength of the support layer 2 is difficult to guarantee. At the same time, there are problems such as leakage of active material, insufficient strength during processing, frequent breakage of electrode sheets, affecting production capacity and yield, and insufficient strength in the later stages of cell cycling, resulting in breakage.

[0123] To further increase and shorten the liquid phase transport path, improve the liquid phase transport rate, and reduce the liquid phase diffusion resistance, thereby further enhancing the wetting ability of the electrode 100, in an optional embodiment, the second hole 23 is a through hole, and multiple second holes 23 are provided, with the multiple second holes 23 distributed at intervals. As an example, the multiple second holes 23 are evenly distributed in an array, which is conducive to more uniform liquid phase transport, relatively small liquid phase diffusion resistance, and also facilitates the opening operation of the second holes 23.

[0124] It should be noted that in the embodiment where multiple second holes 23 are provided in the support layer 2, the dimensions of the multiple second holes 23 may be the same or different, their shapes may be the same or different, and the interval between two adjacent second holes 23 may be the same or different, and none of these are limited here.

[0125] like Figure 5 As shown, in one embodiment of the present invention, the plurality of second holes 23 opened on the support layer 2 are all circular holes with different inner diameters and different spacing between adjacent second holes 23. That is, the second holes 23 adopt a mixture of large holes and small holes. Such a setting can ensure that the electrolyte passes through smoothly.

[0126] Please refer to it again. Figure 3 , Figure 4 and Figure 6 In some embodiments of the present invention, the support layer 2 is provided with a second notch 24 penetrating both surfaces. Thus, the liquid phase (i.e., electrolyte) can be transported through the second notch 24, thereby increasing the liquid phase transport path, shortening the liquid phase transport path, improving the liquid phase transport rate, reducing the liquid phase diffusion resistance, and further enhancing the wetting ability of the electrode 100. The second notch 24 may be elongated, and its specific shape and size can be determined according to actual conditions and are not limited here.

[0127] To further increase and shorten the liquid phase transport path and reduce the liquid phase diffusion resistance, thereby further improving the wetting ability of the electrode 100, in an optional embodiment, the second notch 24 penetrates the two opposite surfaces of the conductive layer 1 and is made in multiples, with the multiple second notches 24 distributed at intervals. As an example, the multiple second notches 24 are evenly distributed in an array, which is conducive to more uniform liquid phase transport, relatively small liquid phase diffusion resistance, and also facilitates the opening operation of the second notch 24.

[0128] It should be noted that in embodiments where multiple second notches 24 are formed in the conductive layer 1, the dimensions of the multiple second notches 24 may be the same or different, their shapes may be the same or different, and the spacing between two adjacent second notches 24 may be the same or different, and none of these are limited here.

[0129] like Figure 6 As shown, in one embodiment, the multiple second grooves 24 formed on the support layer 2 are all elongated strips with different sizes, and the spacing between two adjacent second grooves 24 is also different. That is, the second grooves 24 adopt a mixture of large grooves and small grooves. Such a setting can ensure that the electrolyte passes through smoothly.

[0130] Of course, in other embodiments of the present invention, the support layer 2 is also provided with a second groove 24 and a second hole 23 penetrating both surfaces. This can also increase the liquid phase transport path, shorten the liquid phase transport path, improve the liquid phase transport rate, and reduce the liquid phase diffusion resistance, thereby further improving the wetting ability of the electrode 100. The specific shape, size, and setting position of the second hole 23 and the second groove 24 can be reasonably adjusted according to the actual situation.

[0131] It should be noted that the location of the second hole 23 or the second notch 24 can correspond to the location of the first hole 11 or the first notch 12, or they can be offset; this is not limited here. As an example, the location of the second hole 23 or the second notch 24 corresponds to the location of the first hole 11 or the first notch 12, which enables rapid liquid phase transport and gas intake, resulting in high liquid phase transport efficiency and high gas intake efficiency.

[0132] In this embodiment, the current collector includes a three-layer structure, namely a conductive layer 1, a support layer 2 and a conductive layer 1 stacked in sequence. The conductive layer 1 includes a porous material, and at least one conductive layer 1 has a first hole 11 and / or a first groove 12 penetrating through both surfaces. The support layer 2 has a second hole 23 and / or a second groove 24 penetrating through both surfaces.

[0133] In some embodiments, the support layer 2 is configured as multiple layers, with adjacent support layers 2 being compositely connected, and the conductive layer 1 is disposed on the outer surface of the outermost support layer 2. The support layer 2 is configured as multiple layers, such as a support layer 2 with two layers of porous material, a support layer 2 composed of two layers of porous material and one layer of PET material, or a support layer 2 composed of two or more layers of porous material and one layer of PET material. Compared with traditional current collectors, this can improve the toughness of the current collector and reduce the risk of breakage in the later stages of battery cell cycling. The strength of the multi-layer support layer 2 is increased by 30%, and its wetting efficiency can be increased by more than 60%. Moreover, the wetting efficiency increases significantly with the increase of the number of porous material composite layers.

[0134] Optionally, the number of support layers 2 is 1-4 (e.g., 1, 2, 3 or 4 layers), and the thickness of each layer is 0.5-5μm (e.g., 0.5μm, 1μm, 2μm, 3μm, 5μm and any range between two endpoints).

[0135] It should be noted that each support layer 2 can be made entirely of porous material, and the porous materials of multiple support layers 2 can be the same or different; of course, each support layer 2 can also be a composite of porous material and substrate 22, and the composite porous materials can be the same or different; the thickness of each support layer 2 can be the same or different, and no limitation is made here.

[0136] Certainly, in some embodiments, multiple layers of the support layer 2 and two layers of the conductive layer 1 can be provided simultaneously, and the multiple layers of the support layer 2 and the two layers of the conductive layer 1 are simultaneously perforated and scored. Such a setting can further increase the liquid-phase transmission path, shorten the liquid-phase transmission path, reduce the liquid-phase diffusion impedance, improve the liquid-phase transmission efficiency, and thus improve the wetting ability of the electrode sheet 100 including the current collector.

[0137] In some embodiments, the secondary battery is a lithium-ion battery, and its positive electrode active material includes a ternary material, and its general formula is:

[0138] Li x (Ni a Co b Mn c ) 1-d M d O 2-y A y , where x is 0.2 - 1.2;

[0139] Li x A a (Ni a Co b Mn c ) 1-d M d O 2-y A y , where x + a is 0.2 - 1.2;

[0140] Among them, 0 < a < ¼, 0 < b < ¼, 0 < c < ¼, 0 < d < ¼, M is selected from one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A is selected from one or more of N, F, S, and Cl.

[0141] It should be noted that during the charge and discharge process of the battery, the insertion and extraction and consumption of Li will occur, and the molar content of Li is different when the battery is discharged to different states. The above limitation on x includes the molar content of Li in different charge and discharge states of the battery (usually the battery voltage is between 2 - 5V).

[0142] The ratio of the three elements of Ni, Co, and Mn is approximately 5:2:3 or a similar ratio, that is, 5-series NCM; or, the ratio of the three elements of Ni, Co, and Mn is approximately 6:2:2 or a similar ratio, that is, 6-series NCM. Applying the current collector with the above composite structure of the present invention to the battery system of 5-series NCM or 6-series NCM can effectively solve the problems of cell expansion and corner fracture of the winding structure of the electrode sheet after cycling.

[0143] In some embodiments, the secondary battery is a lithium-ion battery, and its positive electrode active material includes a lithium iron phosphate material, and its general formula is: It should be noted that there seems to be an error in the content you provided. In the formula in item , the range of a, b, c, and d should be 0 < a < ¼, 0 < b < ¼, 0 < c < ¼, 0 < d < ¼ instead of 0 < a < 1, 0 < b < 1, 0 < c < 1, 0 < d < 1 as originally written. I have corrected it in the translation.

[0144] Li a Mn 1-y B y P 1-z C z O 4-n D n a is 0-1.1;

[0145] Li a A x Mn 1-y B y P 1-z C z O 4-n D n a+x is 0-1.1;

[0146] Wherein, B, C, and D are dopant elements or modifying groups, and there is no specific limitation; the subscripts x, y, z, and n all take values ​​from 0 to 1, and there is no specific limitation on their values.

[0147] It should be noted that during the charging and discharging process of the battery, there will be Li insertion / extraction and consumption. The molar content of Li will be different when the battery is discharged to different states. The above limitation on x includes the molar content of Li in different charging and discharging states of the battery (usually the battery voltage is between 2-5V).

[0148] The coating weight of lithium iron phosphate material is >360mg / 1540.25m. 2 Under normal circumstances, under thick coating and high pressure density, the liquid phase resistance and diffusion resistance of the battery cell are relatively large, leading to kinetic failure and lithium deposition. However, the current collector of the electrode in the secondary battery of this invention includes a three-layer composite structure of conductive layer 1, support layer 2, and conductive layer 1. Both conductive layer 1 and support layer 2 have openings or grooves, which can effectively increase the liquid phase transport path, effectively reduce the liquid phase diffusion resistance, and thus improve the wetting ability and kinetics.

[0149] In some embodiments, the secondary battery of the present invention is applied to an energy storage system, comprising multiple battery cells. Currently, in multi-cell systems, when battery cells are stored at high temperatures and sealed, gas is generated during the aging process. This gas cannot be released, leading to lithium plating at the cell interface during full charging, cell swelling, shortened cycle life, and deterioration of expansion force, failing to meet customer requirements and posing quality and safety risks. However, in the secondary battery of the present invention, the support layer 2 of the current collector of the electrode sheet is made of a porous material, which can adsorb the gas generated during aging. Alternatively, the gas can be adsorbed through the perforated and scored structure of the support layer 2 and the conductive layer 1. This effectively solves the problem of deterioration in cell performance and safety due to gas generation.

[0150] A second aspect of the present invention also provides a current collector, the structure of which can be referred to the above embodiments, and will not be described in detail here.

[0151] Please refer to it again. Figures 1 to 4 In one embodiment, the current collector includes a three-layer composite structure of a conductive layer 1, a support layer 2, and a conductive layer 1. The support layer 2 includes a porous material. Each conductive layer 1 has a first hole 11 and / or a first groove 12 penetrating both surfaces. The support layer 2 has a second hole 23 and / or a second groove 24 penetrating both surfaces.

[0152] The support layer 2 can be made of pure porous material or by coating a porous material onto the surface of the substrate 22. In the embodiment where the support layer 2 is made by coating a porous material onto the surface of the substrate 22, the porous material is coated on two opposite surfaces of the substrate 22, either uniformly across the entire surface or intermittently on portions of the surface. This arrangement changes the liquid phase transport path from the surface of the electrode active material layer 3 to four directions between the surface of the electrode active material layer 3 and the interior of the current collector (i.e., two directions of outward transport through the second hole 23 or the second notch 24, and two directions of outward transport through the first hole 11 or the first notch 12), effectively doubling the liquid phase transport path.

[0153] After the cell is dried, it is injected with electrolyte. Because the electrolyte absorption path of electrode 100 is increased by 2 times, the electrolyte injection efficiency is improved by 30%-60%. The wetting path is also increased by 2 times, and the electrolyte creep rate of electrode 100 is increased by 20%-80%. The electrolyte creep rate of bare cell is increased by 20%-80%, thereby shortening the cell wetting time by 20%-80%, increasing the wetting capacity, and reducing the wetting failure rate by more than 60%. Meanwhile, due to the increased wetting rate, the electrolyte consumption during the cycle of the cell makes the electrolyte absorption capacity of the electrode 100 crucial for lithium plating. Through the optimization of the current collector's structure and materials, the electrolyte is rapidly distributed throughout the entire bare cell during the cycle, avoiding lithium plating in thinner areas or on large areas due to insufficient electrolyte at the top, thus greatly improving the cell's lifespan and performance. In addition, due to the modification of the current collector's structure and materials, it can absorb gases generated during the cell aging process and during the cycle, preventing issues such as bubble-like purple spots, black spots, and lithium plating, and avoiding performance degradation and safety problems caused by cell swelling.

[0154] During cell cycling, due to the long cycle time and liquid seepage period, problems such as wetting failure leading to lithium plating and uneven lithium ion distribution resulting in insufficient thermodynamic lithium intercalation sites may occur. To address this issue, the current collector of this invention, through perforation or scoring of the support layer 2 and conductive layer 1, allows lithium ions to be evenly distributed on the A and B surfaces of the electrode 100, thus solving the problem of uneven lithium intercalation and plating during cycling.

[0155] A third aspect of the present invention also provides a method for manufacturing a current collector, used to manufacture the current collector of the second aspect of the present invention.

[0156] In one embodiment of the present invention, the method for manufacturing the current collector includes the following steps:

[0157] Two conductive layers 1 and a support layer 2 are fabricated using conductive and porous materials, respectively, and the two opposing surfaces of the two conductive layers 1 and the support layer 2 are compositely connected to obtain the current collector.

[0158] Specifically, the conductive material can be copper, aluminum, or other conductive materials. Conductive layer 1 can be formed by extrusion coating, transfer coating, spray coating, etc., or by electroplating, electrostatic adsorption, chemical etching, etc., or it can also be made of metal foil, such as copper or aluminum foil. Support layer 2 is made of porous material through extrusion coating, transfer coating, spray coating, etc. The conductive layer 1 and support layer 2 can be bonded together or integrally formed.

[0159] It should be noted that the selection and amount of porous material, as well as the thickness of the support layer 2, can be referred to the above embodiments, and will not be repeated here.

[0160] Compared to traditional metal current collectors, this invention uses a porous material to fabricate the support layer 2, and then composites the two opposing surfaces of the support layer 2 with two conductive layers 1. The resulting three-layer composite current collector can more easily absorb electrolyte, increasing and shortening the liquid phase transport path, reducing liquid phase diffusion resistance, and improving liquid phase transport efficiency, thereby enhancing the wetting ability of the electrode 100 including the current collector. At the same time, the porous material has good gas storage performance, which can absorb the gas generated during the aging process of the battery cell and the gas generated during the cycling process, avoiding problems such as bubble-like purple spots, black spots, and lithium plating in the battery cell, and avoiding performance deterioration and safety issues caused by battery cell swelling.

[0161] In some embodiments, the step of fabricating conductive layer 1 and support layer 2 using conductive material and porous material respectively, and then composite-connecting conductive layer 1 and support layer 2 to obtain the current collector includes:

[0162] The porous material is combined with the substrate 22 to obtain the support layer 2.

[0163] In this embodiment, a composite of porous material and insulating material is used to fabricate the support layer 2. Specifically, the composite method can be to coat the porous material onto the surface of the substrate 22, that is, to coat the porous material onto the surface of the substrate 22 through methods such as extrusion coating, transfer coating, or spray coating, to obtain the support layer 2. Of course, the porous material can also be doped and composited with the raw materials of the substrate 22 before processing to form the support layer 2. The material selection of the substrate 22 can refer to the above embodiments, including but not limited to PET substrates and PP substrates.

[0164] In one embodiment, the step of fabricating a conductive layer 1 and a support layer 2 using conductive and porous materials respectively, and then composite-connecting the conductive layer 1 and the support layer 2 to obtain the current collector includes:

[0165] Porous materials and metal foils are available;

[0166] A support layer 2 is fabricated on the surface of a metal foil using a porous material to obtain the current collector.

[0167] In this embodiment, the conductive layer 1 is a metal foil, such as copper foil or aluminum foil. The metal foil can be purchased or fabricated by methods such as extrusion coating, transfer coating, spray coating, or electroplating, electrostatic adsorption, or chemical etching; no limitation is made here. By coating a porous material onto one surface of the metal foil using methods such as extrusion coating, transfer coating, or spray coating, a current collector can be obtained. This method is simple to operate, and the current collector has good connectivity between layers, resulting in a relatively stable overall structure. Furthermore, in the current collector fabricated in this embodiment, the support layer 2 is made of pure porous material, exhibiting good liquid absorption and gas storage properties.

[0168] In another embodiment, the step of fabricating conductive layer 1 and support layer 2 using conductive material and porous material respectively, and then composite-connecting conductive layer 1 and support layer 2 to obtain the current collector includes:

[0169] Porous materials, substrate 22, and metal foil are provided;

[0170] A porous material is coated on the surface of the substrate 22 to obtain the support layer 2.

[0171] The support layer 2 and the metal foil are combined and connected to obtain the current collector.

[0172] In this embodiment, a support layer 2 is formed by coating a porous material onto the surface of a substrate 22. The porous material can be coated relatively uniformly across the entire surface of the substrate 22, or it can be coated intermittently onto portions of the surface of the substrate 22. For example, the coated porous material can be linear, spiral, S-shaped, Z-shaped, dotted, or other reasonable shapes. The composite method of the support layer 2 and the metal foil includes, but is not limited to, bonding, electroplating, and chemical bonding. As an example, the composite method of the support layer 2 and the metal foil is bonding, which is simple to operate and provides a relatively strong connection.

[0173] In another embodiment, the step of fabricating conductive layer 1 and support layer 2 using conductive material and porous material respectively, and then composite-connecting conductive layer 1 and support layer 2 to obtain the current collector includes:

[0174] Porous materials, conductive materials, and substrates are provided 22;

[0175] A porous material layer 21 is fabricated on the surface of the substrate 22 using porous materials;

[0176] A conductive layer 1 is fabricated on the surface of the porous material layer 21 facing away from the substrate 22 using a conductive material to obtain the current collector.

[0177] In this embodiment, the substrate 22 includes, but is not limited to, PET substrate and / or PP substrate. A porous material is coated on one surface of the substrate 22 to form a porous material layer 21. The porous material layer 21 and the substrate 22 together constitute the support layer 2 of the present invention. A conductive layer 1 is formed on the surface of the porous material layer 21 facing away from the substrate 22 by spraying, deposition or other reasonable means. Alternatively, a conductive material layer can be laminated on the surface of the porous material layer 21 facing away from the substrate 22 by electroplating, electrostatic adsorption, chemical etching or other methods to obtain a current collector.

[0178] It should be noted that the porous material can be applied relatively evenly to the entire surface of the substrate 22, or it can be applied intermittently to a portion of the surface of the substrate 22. For example, the applied porous material can be linear, spiral, S-shaped, Z-shaped, dotted, or other reasonable shapes.

[0179] In some embodiments, the step of fabricating conductive layer 1 and support layer 2 using conductive material and porous material respectively, and then composite-connecting conductive layer 1 and support layer 2 to obtain the current collector further includes:

[0180] An opening is made in conductive layer 1; and / or,

[0181] Score the conductive layer 1.

[0182] The present invention makes openings and / or grooves in the conductive layer 1, which can increase the liquid phase transport path, shorten the liquid phase transport path, improve the liquid phase transport rate, reduce the liquid phase diffusion resistance, and further improve the wetting ability of the electrode 100.

[0183] The size and shape design of the opening and the groove can refer to the design of the first opening 11 and the first groove 12 in the above embodiment, and will not be repeated here.

[0184] In some embodiments, the step of fabricating conductive layer 1 and support layer 2 using conductive material and porous material respectively, and then composite-connecting conductive layer 1 and support layer 2 to obtain the current collector includes:

[0185] Two conductive layers 1 are made of conductive material, and a support layer 2 is made of porous material;

[0186] Two conductive layers 1 are compositely connected to the two opposite surfaces of the support layer 2 to obtain the current collector.

[0187] When the conductive layer 1 is a metal foil and the support layer 2 is a pure porous material, the porous material is first processed into a sheet-like support layer 2, and then the two metal foils are respectively bonded to the opposite surfaces of the support layer 2 to obtain a current collector; or, the porous material is coated onto the surface of a metal foil by means of extrusion coating, transfer coating, spray coating, etc., to form a composite metal foil and support layer 2, and then another metal foil is bonded to the support layer 2 to obtain a current collector.

[0188] When the conductive layer 1 is a metal foil and the support layer 2 includes a substrate 22 doped with porous material, the porous material is first coated on the two opposite surfaces of the substrate 22 by means of extrusion coating, transfer coating, spray coating, etc., to obtain the support layer 2. Then, the two metal foils are respectively bonded to the two opposite surfaces of the support layer 2 to obtain the current collector.

[0189] When the conductive layer 1 is made of a conductive material and the support layer 2 includes a substrate 22 doped with porous material, the porous material is first coated on the two opposite surfaces of the substrate 22 by means of extrusion coating, transfer coating, spray coating, etc., to obtain the support layer 2. Then, the conductive material (such as metal powder) is coated on the two opposite surfaces of the support layer 2 by means of extrusion coating, transfer coating, spray coating, etc., or a layer of conductive material is laminated on the two opposite surfaces of the support layer 2 by means of electroplating, electrostatic adsorption, chemical etching, etc., to obtain the current collector.

[0190] In the process of fabricating a composite current collector consisting of two conductive layers 1 and one support layer 2, the present invention requires opening holes or scoring grooves in the conductive layer 1 to further increase the liquid phase transport path, shorten the liquid phase transport path, improve the liquid phase transport rate, reduce the liquid phase diffusion resistance, and further improve the wetting ability of the electrode 100.

[0191] It should be noted that the thickness design of conductive layer 1 and support layer 2 can refer to the above embodiments, and will not be repeated here.

[0192] In other embodiments, the step of fabricating conductive layer 1 and support layer 2 using conductive material and porous material respectively, and then composite-connecting conductive layer 1 and support layer 2 to obtain the current collector, further includes:

[0193] A conductive layer 1 is made of a conductive material, and multiple support layers 2 are made of a porous material.

[0194] Multiple support layers 2 are compositely connected, and a conductive layer 1 is compositely connected to the outermost support layer 2 to obtain the current collector.

[0195] In this embodiment, the support layer 2 is made into a multi-layer composite structure, which can improve the toughness of the current collector, reduce the risk of breakage in the later stages of cell cycling, and reduce the cost of the current collector. In addition, some porous materials, dehydrating agents, lithium replenishing agents, gel additives, film-forming additives, etc. can be incorporated into the support layer 2 to solve problems such as cell gas generation, wetting, SEI film formation, cell life improvement, and electrolyte solidification. At the same time, it can reduce problems such as strip breakage and poor welding during the manufacturing process and improve the manufacturing yield.

[0196] The design of the number of layers and thickness of the support layer 2 can be referred to the above embodiments, and will not be repeated here.

[0197] Furthermore, in some embodiments of the present invention, the step of fabricating the conductive layer 1 and the support layer 2 using conductive material and porous material respectively, and then composite-connecting the conductive layer 1 and the support layer 2 to obtain the current collector further includes:

[0198] An opening is made in the support layer 2; and / or,

[0199] Score the support layer 2.

[0200] In this embodiment, the support layer 2 is designed with openings and / or grooves to further increase and shorten the liquid phase transport path, improve the liquid phase transport rate, and reduce the liquid phase diffusion resistance, thereby further improving the wetting ability of the electrode 100. The shape, size, and position of the openings and grooves can refer to the design of the second opening 23 and the second groove 24 in the above embodiment, and will not be repeated here.

[0201] Please refer to it again. Figures 1 to 4The third aspect of the present invention also provides an electrode 100, the electrode 100 including an electrode active material layer 3 and a current collector provided in the first aspect of the present invention, wherein the electrode active material layer 3 is disposed on the side of the conductive layer 1 away from the support layer 2, specifically, the electrode active material layer 3 is coated on the surface of the conductive layer 1 by means of extrusion coating, transfer coating, spray coating or the like.

[0202] Optionally, the electrode active material layer 3 is positively polarized, and correspondingly, the electrode 100 is a positive electrode 100; or, the electrode active material layer 3 is negatively polarized, and correspondingly, the electrode 100 is a negative electrode 100.

[0203] In some embodiments, the electrode 100 is a positive electrode 100, and the electrode active material layer 3 is a positive electrode slurry prepared by dispersing the positive electrode active material, conductive agent, binder, dispersant, and any other components in the solvent N-methylpyrrolidone. The positive electrode active material includes, but is not limited to, at least one of lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium-rich manganese-based materials, and sodium-ion batteries. The conductive agent includes, but is not limited to, at least one of carbon black, acetylene black, carbon nanotubes, carbon fibers, Ketjen black, and graphene. The binder includes, but is not limited to, at least one of polyvinylidene fluoride, polyvinylidene fluoride copolymer, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyamide, polyethylene ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, and styrene-butadiene rubber. Dispersants include, but are not limited to, aqueous dispersants, oil-based dispersants, and linear dispersants, such as polyether siloxanes, modified propylene siloxanes, and modified fluorocarbon siloxanes.

[0204] In some embodiments, the electrode 100 is a negative electrode 100, and the electrode active material layer 3 is a negative electrode slurry prepared by dispersing the negative electrode active material, conductive agent, binder, dispersant, and any other components in the solvent N-methylpyrrolidone. The negative electrode active material contains graphite or silicon, including but not limited to graphite slurry and graphite-silicon slurry.

[0205] Typically, secondary batteries (such as lithium-ion batteries) also include an electrolyte. During the charging and discharging process, active ions move back and forth between the positive and negative electrodes, inserting and extracting. The electrolyte acts as a conductor of ions between the positive and negative electrodes. A separator is placed between the positive and negative electrodes, primarily to prevent short circuits between the positive and negative electrodes, while also allowing ions to pass through.

[0206] [Positive electrode plate]

[0207] The positive electrode sheet includes a positive current collector and a positive film layer disposed on at least one surface of the positive current collector, wherein the positive current collector is the current collector provided in the second aspect of the present invention or the current collector prepared by the current collector preparation method provided in the third aspect.

[0208] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0209] In some embodiments, the secondary battery is a lithium-ion battery, and the positive electrode active material can be a positive electrode active material known in the art for lithium-ion batteries. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present invention is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for secondary batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0210] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0211] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0212] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0213] [Negative electrode plate]

[0214] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material, and the negative current collector is the current collector provided in the first aspect of the present invention.

[0215] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0216] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in secondary batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present invention is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for secondary batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0217] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0218] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0219] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0220] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0221] Electrolyte

[0222] The electrolyte plays a role in conducting ions between the positive and negative electrode plates.

[0223] In some embodiments, the electrolyte comprises an electrolyte salt and a solvent.

[0224] In some embodiments, the secondary battery is a lithium-ion battery, and its electrolyte includes lithium hexafluorophosphate or a mixture of lithium hexafluorophosphate and other lithium salts, wherein the other lithium salts may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0225] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0226] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain performance characteristics of the secondary battery, such as additives that improve the overcharge performance of the secondary battery, additives that improve the high-temperature or low-temperature performance of the secondary battery, etc.

[0227] [Isolation membrane]

[0228] In some embodiments, the secondary battery is a lithium-ion battery and also includes a separator. This invention does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0229] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0230] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0231] In some embodiments, the lithium-ion battery may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and electrolyte described above.

[0232] In some implementations, the outer packaging of a lithium-ion battery can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of a lithium-ion battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0233] A fifth aspect of the present invention also provides an electrical device comprising the secondary battery described above. The electrical device of the present invention possesses at least all the beneficial effects of the aforementioned secondary battery, which will not be elaborated further here. The secondary battery can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0234] As an example, the electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, a mobile phone, a tablet computer, a laptop computer, etc.

[0235] Example

[0236] The following describes embodiments of the present invention. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0237] Example 1

[0238] 1. Fabrication of current collectors

[0239] (1) MOFs material is coated on both surfaces of a PET substrate to obtain a support layer. The support layer is then perforated. The coating thickness is 0.5 μm, and the coating method is spin-spraying. MOF-OH can be used as the MOFs material. The perforation (i.e., the second hole) in the support layer is a circular hole with a diameter of 0.5 μm, penetrating both opposite surfaces of the support layer. The thickness of the support layer is 15 μm, and the porosity of the MOFs material is 60%. (2) The two surfaces of the support layer are bonded to two copper foils respectively. The copper foils are then perforated. The perforation (i.e., the first hole) in the copper foil is a circular hole with a diameter of 0.5 μm, penetrating both opposite surfaces of the copper foil. The thickness of the copper foil is 15 μm. See Table 1 for detailed parameters.

[0240] 2. Production of positive electrode sheets

[0241] A positive electrode slurry is coated onto the surface of the current collector to form a positive electrode active material layer, thus obtaining the positive electrode sheet. The positive electrode slurry includes a positive electrode active material, a conductive agent, a binder, a dispersant, and a solvent, N-methylpyrrolidone. By mass parts, the positive electrode active material is 9 parts, the conductive agent is 2 parts, the binder is 3 parts, the dispersant is 2 parts, and the solvent is 3 parts.

[0242] 3. Fabrication of the negative electrode sheet

[0243] A negative electrode slurry is coated onto the surface of the current collector to form a negative electrode active material layer, thus obtaining the negative electrode sheet. The negative electrode slurry includes a negative electrode active material, a conductive agent, a binder, a dispersant, and a solvent (water). By mass parts, the negative electrode active material is 90 parts, the conductive agent is 2 parts, the binder is 3 parts, the dispersant is 2 parts, and the solvent is 3 parts.

[0244] 4. Cell assembly

[0245] The positive electrode, separator, and negative electrode are wound in sequence, with the separator positioned between the positive and negative electrodes, to obtain the battery cell.

[0246] Example 2

[0247] The difference from Example 1 is that the MOF material coating thickness is 10 μm, while all other operations are the same as in Example 1. See Table 1 for detailed parameters.

[0248] Example 3

[0249] The difference from Example 1 is that the MOF material coating thickness is 30 μm, while all other operations are the same as in Example 1. See Table 1 for detailed parameters.

[0250] Example 4

[0251] The difference from Example 1 is that the MOF material coating thickness is 50 μm, while all other operations are the same as in Example 1. See Table 1 for detailed parameters.

[0252] Example 5

[0253] The difference from Example 1 is that the pore size of the second hole is 0.5 μm; all other operations are the same as in Example 1. See Table 1 for detailed parameters.

[0254] Example 6

[0255] The difference from Example 1 is that the pore size of the second hole is 2 μm; all other operations are the same as in Example 1. See Table 1 for detailed parameters.

[0256] Example 7

[0257] The difference from Example 1 is that the pore size of the second hole is 3.5 μm; all other operations are the same as in Example 1. See Table 1 for detailed parameters.

[0258] Example 8

[0259] The difference from Example 1 is that the pore size of the second hole is 5 μm, while all other operations are the same as in Example 1. See Table 1 for detailed parameters.

[0260] Example 9

[0261] The difference from Example 1 is that the diameter of the first hole is 0.5 μm, while all other operations are the same as in Example 1. See Table 1 for detailed parameters.

[0262] Example 10

[0263] The difference from Example 1 is that the pore size of the first hole is 2 μm, while all other operations are the same as in Example 1. See Table 1 for detailed parameters.

[0264] Example 11

[0265] The difference from Example 1 is that the pore size of the first hole is 3.5 μm, while all other operations are the same as in Example 1. See Table 1 for detailed parameters.

[0266] Example 12

[0267] The difference from Example 1 is that the diameter of the first hole is 5 μm, while all other operations are the same as in Example 1. See Table 1 for detailed parameters.

[0268] Example 13

[0269] The difference from Example 1 is that the support layer is made of pure MOF material in a sheet structure, with the same thickness as in Example 1. The porosity of the MOF material is 1%, and all other operations are the same as in Example 1. See Table 1 for detailed parameters.

[0270] Example 14

[0271] The difference from Example 13 is that the porosity of the MOFs material is 10%, while all other parameters are the same as in Example 13. See Table 1 for details.

[0272] Example 15

[0273] The difference from Example 13 is that the porosity of the MOFs material is 30%, while all other parameters are the same as in Example 13. See Table 1 for details.

[0274] Comparative Example 1

[0275] The difference between this comparative example and Example 1 is that the current collector used is a common composite current collector, namely a composite current collector consisting of a conductive layer + a PET substrate + a conductive layer. Neither the PET substrate nor the conductive layer is perforated or scored. All other operations are the same as in Example 1. See Table 1 for detailed parameters.

[0276] After drying the cells obtained in Examples 1-15 and Comparative Example 1, the cells were injected with electrolyte. The electrolyte injection efficiency was tested using the electrolyte injection curve test method. The liquid seepage rate, liquid level rise height, and wetting failure rate were tested using the electrode capillary aspiration method, the JR liquid seepage method, and the wetting window confirmation method to verify the wetting effect of the composite current collector. Based on Comparative Example 1, the percentage increase in electrolyte injection efficiency, percentage increase in liquid seepage rate, percentage decrease in liquid level rise height, and percentage decrease in wetting failure rate for Examples 1-15 were calculated, and the data are shown in Table 2.

[0277] As can be seen from the data in Table 2, compared with Comparative Example 1, the liquid injection efficiency of Examples 1-15 of the present invention is increased by 30%-60% due to the increase of the electrode liquid absorption path by 2 times; at the same time, the wetting path is also increased by 2 times, the liquid creep rate of the electrode is increased by 20%-80%, and the liquid creep rate of the bare cell is increased by 20%-80%, thereby shortening the cell wetting time by 20%-80%, increasing the wetting capacity, and reducing the wetting failure rate by more than 60%.

[0278] As can be seen from the comparison of Examples 1-4, as the thickness of the porous material increases, the percentage increase in injection efficiency, the percentage increase in creep rate, the percentage decrease in liquid surface creep height, and the percentage decrease in wetting failure rate all show a significant increase.

[0279] By comparing Examples 1 and Examples 5-8, it can be seen that as the pore size of the second hole on the support layer increases, the percentage increase in injection efficiency, the percentage increase in creep rate, the percentage decrease in liquid surface creep height, and the percentage decrease in wetting failure rate all show a significant increase.

[0280] By comparing Examples 1 and Examples 9-12, it can be seen that as the pore size of the second hole on the support layer increases, the percentage increase in injection efficiency, the percentage increase in creep rate, the height of liquid surface rise, and the percentage decrease in wetting failure rate all show a significant increase.

[0281] Comparative examples 13-15 show that when the support layer is made of pure MOF material, as the porosity of the porous material increases, the percentage increase in injection efficiency, the percentage increase in creep rate, the height of liquid surface rise, and the percentage decrease in wetting failure rate all show a significant increase.

[0282] Table 1. Parameters of Examples 1-15 and Comparative Example 1

[0283]

[0284]

[0285] Table 2 Performance of Examples 1-15 and Comparative Examples 1-4

[0286]

[0287]

[0288] Figure 7 This is a schematic diagram comparing the wetting rates of the battery cells obtained in Embodiment 1 and Comparative Example 1 of the present invention. Figure 7 As can be seen, the wetting rate of the battery cell obtained in Example 1 is much higher than that of the battery cell obtained in Comparative Example 1. There is a significant difference from the initial electrolyte climbing height. The electrolyte climbing height of Comparative Example 1 can only reach 15 mm within 2 hours, while the electrolyte climbing height of Example 1 reaches 80 mm within 2 hours. Moreover, the electrolyte climbing height of Example 1 shows a continuously increasing rate, while the liquid level climbing height of Comparative Example 1 gradually becomes flat and the liquid absorption rate slowly decreases. In particular, after 20 minutes, the liquid level climbing rate of Comparative Example 1 basically shows a slight climbing wetting effect.

[0289] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A secondary battery characterized by comprising: The pole piece comprises a current collector and an electrode active material layer arranged on at least one surface of the current collector. The current collector comprises a support layer and a conductive layer arranged on both surfaces of the support layer, wherein the support layer comprises a porous material.

2. The secondary battery according to claim 1, wherein The pore size of the porous material is 0.1-5 μm; and / or, The specific surface area of the porous material is 10 m 2 / g-60 m 2 / g; and / or, The tortuosity of the pore structure of the porous material is 50%-80%.

3. The secondary battery according to claim 2, wherein The porous material comprises at least one of a covalent organic framework material and derivatives thereof, a metal organic framework compound material and derivatives thereof, a fiber material, a carbon cloth material, and a carbon nanotube.

4. The secondary battery according to claim 1, wherein The support layer further comprises a substrate, and the porous material is combined with the substrate.

5. The secondary battery according to any one of claims 1 to 4, wherein The porosity of the current collector is 30%-65%.

6. The secondary battery according to claim 5, wherein The mass of the porous material accounts for 1%-100% of the mass of the support layer; and / or, The thickness of the support layer is 0.5-15 μm; and / or, The thickness of the conductive layer is 0.5-15 μm.

7. The secondary battery according to claim 5, wherein the negative electrode is a lithium metal electrode. The conductive layer is provided with a first hole; and / or, The conductive layer is provided with a first notch; and / or, The conductive layer comprises a plurality of conductive parts, and the plurality of conductive parts are arranged on at least one surface of the support layer.

8. The secondary battery according to claim 7, wherein The support layer is provided in multiple layers, and adjacent two layers of the support layer are combined and connected, and the conductive layer is arranged on the outer surface of the outermost support layer.

9. The secondary battery according to claim 7, wherein the negative electrode is a lithium metal electrode. The support layer is provided with a second hole; and / or, The support layer is provided with a second notch.

10. A current collector characterized by comprising: The current collector comprises a support layer and a conductive layer arranged on both surfaces of the support layer, wherein the support layer comprises a porous material.

11. The current collector of claim 10, wherein The support layer further comprises a substrate, and the porous material is combined and connected with the substrate.

12. The current collector of claim 10 or 11, wherein The porosity of the current collector is 1%-80%.

13. The current collector of claim 12, wherein The porosity of the current collector is 30%-65%.

14. The current collector of claim 12, wherein The conductive layer is provided with a first hole; and / or, The conductive layer is provided with a first notch; and / or, The conductive layer comprises a plurality of conductive parts, and the plurality of conductive parts are arranged on one surface of the support layer.

15. The current collector of claim 12, wherein The support layer is provided in multiple layers, and adjacent two layers of the support layer are combined and connected, and the conductive layer is connected to the surface of the outermost support layer; and / or, The support layer is provided with a second hole; and / or, The support layer is provided with a second notch.

16. A method of making a current collector, comprising: The method comprises the following steps: Two conductive layers and a support layer are respectively made of a conductive material and a porous material, and the opposite two surfaces of the two conductive layers and the support layer are combined and connected to obtain the current collector.

17. The method of claim 16, wherein In the step of making a conductive layer and a support layer from a conductive material and a porous material respectively and combining and connecting the conductive layer and the support layer to obtain the current collector, the following steps are further included: The porous material is combined with a substrate to obtain the support layer.

18. The method of claim 16, wherein In the step of making a conductive layer and a support layer from a conductive material and a porous material respectively and combining and connecting the conductive layer and the support layer to obtain the current collector, the following steps are further included: The conductive layer is perforated; and / or, The conductive layer is notched.

19. The method of claim 16, wherein In the step of making a conductive layer and a support layer from a conductive material and a porous material respectively and combining and connecting the conductive layer and the support layer to obtain the current collector, the following steps are further included: The conductive layer is made of a conductive material, and a plurality of support layers are made of a porous material. The plurality of support layers are stacked and connected, and the conductive layer is connected to the outermost support layer to obtain the current collector.

20. The method of making a current collector of any one of claims 16 to 19, wherein, The conductive layer and the support layer are made of conductive material and porous material respectively, and the conductive layer and the support layer are connected to obtain the current collector. The support layer is perforated; and / or The support layer is scored.

21. A pole piece characterized by, The pole piece comprises an electrode active material layer and a current collector as claimed in any one of claims 10 to 15 or a current collector made by the method as claimed in any one of claims 16 to 20, and the electrode active material layer is arranged on the side of the current collector away from the support layer.

22. An electrical device, comprising: The electric device comprises a secondary battery as claimed in any one of claims 1 to 9.

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