Secondary battery and electric device
By setting a porous coating at the corner of the secondary battery electrode, the problem of uneven electrolyte wetting in the corner area is solved, the electrolyte is effectively compensated, lithium plating and black spots are avoided, and the cycle performance and safety of the battery are improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHEJIANG LIWINON ENERGY TECHNOLOGY CO LTD
- Filing Date
- 2025-06-20
- Publication Date
- 2026-07-14
AI Technical Summary
In the corner areas of the wound secondary battery, the bending stress concentration and uneven electrolyte wetting lead to insufficient local electrolyte retention, resulting in lithium plating or black spots, which causes capacity decay and safety risks. Existing technical solutions have problems such as complex processes, high costs or insufficient electrolyte replenishment capabilities.
A porous coating is set at the corner of the positive or negative electrode of the secondary battery, and the porosity is controlled to be 20-80%. During the charge and discharge cycle, the electrolyte is squeezed out to the corner area through the porous coating, which compensates for electrolyte loss and avoids lithium plating and black spot formation.
It effectively improves the cycle performance and safety of secondary batteries. Through the electrolyte adsorption effect of the porous coating, it compensates for electrolyte loss, avoids lithium plating and black spots, and enhances the structural stability and capacity of the battery.
Smart Images
Figure CN224501900U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of battery technology, specifically to a secondary battery and an electrical device. Background Technology
[0002] Secondary batteries with wound structures are widely used due to their simple manufacturing process and high energy density. However, due to the concentration of bending stress and uneven electrolyte wetting in the corner areas, local insufficient electrolyte retention can easily occur, leading to lithium plating or black spots in the later stages of cycling, resulting in capacity decay and safety risks.
[0003] To address the issues of stress concentration and uneven electrolyte wetting in corner areas, current approaches primarily focus on three aspects: structural optimization, process adjustment, and material modification. Existing technologies optimize the corner structure and improve electrolyte wetting by storing electrolyte in the corner gap or inserting internal supports to reduce curvature. Other technologies mitigate stress concentration in corner areas by adjusting roller pressure to control electrode thickness distribution. Additionally, existing technologies address stress concentration and uneven electrolyte wetting in corner areas by designing alternating protrusions on the diaphragm surface to allow for expansion space. However, these solutions suffer from drawbacks such as complex processes, high costs, or insufficient electrolyte replenishment capacity.
[0004] Therefore, this application is submitted. Utility Model Content
[0005] The purpose of this application is to overcome the shortcomings of the existing technology and provide a secondary battery and power device that can effectively compensate for electrolyte loss during the cycle, avoid lithium plating, and prevent black spots from forming at corners, thereby effectively improving the cycle performance and safety of the secondary battery.
[0006] To achieve the above objectives, in a first aspect of this application, a secondary battery is provided, including a wound cell, the wound cell including a flat region and a corner region, the wound cell including a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode; the positive electrode includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector, and the negative electrode includes a negative current collector and a negative active material layer disposed on at least one surface of the negative current collector;
[0007] The positive electrode active material layer has a porous coating on the surface of the corner area facing the separator and / or the negative electrode active material layer has a porous coating on the surface of the corner area facing the separator.
[0008] The porosity of the porous coating is 20-80%.
[0009] In some embodiments, the porosity of the porous coating is 30-80%.
[0010] In some embodiments, the adhesion between the porous coating and the positive electrode active material layer is ≥3N.
[0011] In some embodiments, the adhesion between the porous coating and the negative electrode active material layer is ≥3N.
[0012] In some embodiments, the thickness of the porous coating on the corner region facing the separator of the positive electrode active material layer is 10 to 60% of the thickness of the positive electrode active material layer.
[0013] In some embodiments, the thickness of the porous coating on the corner region facing the separator of the negative electrode active material layer is 10-60% of the thickness of the negative electrode active material layer. In some embodiments, the thickness of the positive electrode active material layer is 40-140 μm.
[0014] In some embodiments, the thickness of the negative electrode active material layer is 50–160 μm.
[0015] In some embodiments, the thickness of the porous coating on the corner region facing the separator of the positive electrode active material layer is 4 to 84 μm.
[0016] In some embodiments, the thickness of the porous coating on the corner region facing the diaphragm of the negative electrode active material layer is 5–96 μm.
[0017] In some embodiments, the thickness of the positive current collector is 5–10 μm.
[0018] In some embodiments, the thickness of the negative electrode current collector is 3–8 μm.
[0019] In a second aspect, this application provides an electrical device including the aforementioned secondary battery.
[0020] The beneficial effects of this application are as follows: By providing a porous coating on the surface of the corner of the positive electrode and / or negative electrode, and controlling the porosity of the porous coating to be 20-80%, the porous coating has excellent electrolyte adsorption effect. During the charge and discharge cycle of the secondary battery, as the cell expands laterally, it squeezes the porous coating that adsorbs the electrolyte, releasing the stored electrolyte to the corner area, compensating for electrolyte loss during the cycle, avoiding lithium plating, and preventing the formation of black spots at the corner, thus effectively improving the cycle performance and safety of the secondary battery. Attached Figure Description
[0021] Figure 1This is a schematic diagram of the structure of a secondary battery according to an embodiment of this application.
[0022] Figure 2 This is a schematic diagram of the structure of a secondary battery according to another embodiment of this application.
[0023] Figure 3 This is a schematic diagram of the structure of a secondary battery according to another embodiment of this application.
[0024] The markings in the diagram are: 1. Positive electrode sheet; 11. Positive current collector; 12. Positive active material layer; 2. Negative electrode sheet; 21. Negative current collector; 22. Negative active material layer; 3. Separator; 4. Porous coating. Detailed Implementation
[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0026] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.
[0027] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.
[0028] In this application, there are no particular restrictions on the specific dispersion and mixing methods.
[0029] Unless otherwise specified, all components, raw materials, or instruments used in the embodiments and comparative examples of this application are commercially available, and the components and raw materials used in each parallel experiment are the same.
[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0031] The term "rechargeable battery," also known as a rechargeable battery or accumulator, refers to a battery that can be recharged after being discharged to activate its active materials and continue to be used.
[0032] like Figure 1 As shown, in one embodiment, this application provides a secondary battery including a wound cell, the wound cell including a flat region and a corner region, the wound cell including a positive electrode 1, a negative electrode 2 and a separator 3 between the positive electrode 1 and the negative electrode 2; the positive electrode 1 includes a positive current collector 11 and a positive active material layer 12 disposed on at least one surface of the positive current collector 11, the negative electrode 2 includes a negative current collector 21 and a negative active material layer 22 disposed on at least one surface of the negative current collector 21;
[0033] The positive electrode active material layer 12 has a porous coating 4 on the surface of the corner area facing the separator;
[0034] The porosity of the porous coating 4 is 20-80%.
[0035] This application provides a porous coating 4 on the surface of the corner of the positive electrode 1, and controls the porosity of the porous coating 4 to be 20-80%. The porous coating 4 has excellent electrolyte adsorption effect. During the charge and discharge cycle of the secondary battery, as the cell expands laterally, it compresses the porous coating 4 that adsorbs the electrolyte, releasing the stored electrolyte to the corner area, compensating for electrolyte loss during the cycle, avoiding lithium plating, and preventing the formation of black spots at the corner, effectively improving the cycle performance and safety of the secondary battery.
[0036] In one embodiment, the porosity of the porous coating 4 is 30-80%.
[0037] In one embodiment, the thickness of the porous coating 4 on the corner region of the positive electrode active material layer 12 facing the separator 3 is 10-60% of the thickness of the positive electrode active material layer 12. By controlling the relationship between the thickness of the porous coating 4 on the corner region of the positive electrode active material layer 12 facing the separator 3 and the positive electrode active material layer 12 within this range, the liquid absorption capacity of the porous coating 4 on its surface can be improved, the electrolyte retention at the corner of the positive electrode active material layer 12 can be increased, and the stress at the corner of the positive electrode active material layer 12 can be effectively relieved, thereby improving the structural stability of the cell and effectively improving the capacity and safety of the secondary battery.
[0038] In one embodiment, the thickness of the positive electrode active material layer 12 is 40–140 μm.
[0039] In one embodiment, the thickness of the porous coating 4 on the surface of the positive electrode active material layer 12 facing the separator 3 in the corner area is 4 to 84 μm. By controlling the thickness of the porous coating within this range, the stability of the secondary battery can be improved, the liquid absorption performance can be improved, the electrolyte retention at the corner of the battery can be increased, lithium plating at the corner can be further avoided, and black spots can be avoided at the corner.
[0040] In one embodiment, the thickness of the negative electrode active material layer 22 is 50–160 μm.
[0041] In one embodiment, the thickness of the positive current collector 11 is 5 to 10 μm.
[0042] In one embodiment, the thickness of the negative electrode current collector 21 is 3 to 8 μm.
[0043] In one embodiment, the adhesion between the porous coating 4 and the positive electrode active material layer 12 is ≥3N.
[0044] like Figure 2 As shown, in one embodiment, this application provides a secondary battery including a wound cell, the wound cell including a flat region and a corner region, the wound cell including a positive electrode 1, a negative electrode 2 and a separator 3 between the positive electrode 1 and the negative electrode 2; the positive electrode 1 includes a positive current collector 11 and a positive active material layer 12 disposed on at least one surface of the positive current collector 11, the negative electrode 2 includes a negative current collector 21 and a negative active material layer 22 disposed on at least one surface of the negative current collector 21;
[0045] The negative electrode active material layer 22 has a porous coating 4 on the surface of the corner area facing the diaphragm;
[0046] The porosity of the porous coating 4 is 20-80%.
[0047] This application provides a porous coating 4 on the surface of the corner of the negative electrode 2, and controls the porosity of the porous coating 4 to be 20-80%. The porous coating 4 has excellent electrolyte adsorption effect. During the charge and discharge cycle of the secondary battery, as the cell expands laterally, it squeezes the porous coating 4 that adsorbs the electrolyte, releasing the stored electrolyte to the corner area, compensating for electrolyte loss during the cycle, avoiding lithium plating, and preventing the formation of black spots at the corner, effectively improving the cycle performance and safety of the secondary battery.
[0048] In one embodiment, the thickness of the porous coating 4 on the corner region of the negative electrode active material layer 22 facing the separator 3 is 10-60% of the thickness of the negative electrode active material layer 22. By controlling the relationship between the thickness of the porous coating 4 on the corner region of the negative electrode active material layer 22 facing the separator 3 and the negative electrode active material layer 22 within this range, the liquid absorption capacity of the porous coating 4 on its surface can be improved, the electrolyte retention at the corner of the negative electrode active material layer 22 can be increased, and the stress at the corner of the negative electrode active material layer 22 can be effectively relieved, thereby improving the structural stability of the cell and effectively improving the capacity and safety of the secondary battery.
[0049] The thickness of the porous coating 4 on the corner region facing the diaphragm 3 of the negative electrode active material layer 22 is 5-96 μm.
[0050] In one embodiment, the adhesion between the porous coating 4 and the negative electrode active material layer 22 is ≥3N.
[0051] like Figure 3 As shown, in one embodiment, this application provides a secondary battery including a wound cell. The wound cell includes a flat region and a corner region. The wound cell includes a positive electrode 1, a negative electrode 2, and a separator 3 between the positive electrode 1 and the negative electrode 2. The positive electrode 1 includes a positive current collector 11 and a positive active material layer disposed on at least one surface of the positive current collector 11. The negative electrode 2 includes a negative current collector 21 and a negative active material layer disposed on at least one surface of the negative current collector 21.
[0052] The positive electrode active material layer 12 has a porous coating 4 on the surface of the corner area facing the separator; the negative electrode active material layer 22 has a porous coating 4 on the surface of the corner area facing the separator; the negative electrode active material layer 22 has a porous coating 4 on the surface of the corner area facing the separator.
[0053] This application provides a porous coating 4 at the corner of the positive electrode 1 and the negative electrode 2, and controls the porosity of the porous coating 4 to be 20-80%. The porous coating 4 has excellent electrolyte adsorption effect. During the charge and discharge cycle of the secondary battery, as the cell expands laterally, it compresses the porous coating 4 that adsorbs the electrolyte, releasing the stored electrolyte to the corner area, compensating for electrolyte loss during the cycle, avoiding lithium plating, and preventing the formation of black spots at the corner, effectively improving the cycle performance and safety of the secondary battery.
[0054] In some embodiments, the porous coating 4 includes at least one of polyvinylidene fluoride (PVDF), polyacrylate, and polyvinyl butyral (PVB).
[0055] In some embodiments, the porous coating 4 is made by dissolving a polymer substrate and a pore-forming agent in a solvent and then forming a film / drying it; or it is made by 3D printing a polymer.
[0056] In some embodiments, the pore-forming agent includes, but is not limited to, one or more of naphthalene, benzoic acid, isopropanol, polyethylene glycol (PEG 400), polyvinylpyrrolidone (PVP), etc.
[0057] In some embodiments, the solvent includes, but is not limited to, one or more of N-methylpyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), tetrahydrofuran (THF), dimethyl carbonate (DMC), etc.
[0058] In one embodiment, the positive electrode active material layer 12 includes a positive electrode active material, which includes at least one of lithium cobalt oxide (LCO), nickel cobalt manganese ternary material (NCM), nickel cobalt aluminum ternary material (NCA), nickel cobalt manganese aluminum quaternary material (NCMA), lithium iron phosphate (LFP), lithium manganese phosphate (LMP), lithium vanadium phosphate (LVP), and lithium manganese oxide (LMO).
[0059] In one embodiment, the mass percentage of the positive electrode active material in the positive electrode active material layer 12 is 90-99%, for example, it can be 90%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or any two of these values.
[0060] In one embodiment, the positive electrode active material layer 12 further includes a conductive agent and a binder.
[0061] In one embodiment, the conductive agent has a mass percentage content of 0.5% to 5% in the positive electrode active material layer 12, for example, it can be 0.5%, 1%, 2%, 3%, 4%, 5% or any two of these values.
[0062] In one embodiment, the binder has a mass percentage content of 0.5% to 5% in the positive electrode active material layer 12, for example, it can be 0.5%, 1%, 2%, 3%, 4%, 5% or any two of these values.
[0063] In this application, the type of positive electrode current collector 11 is not particularly limited, and it can be any known material suitable for use as the positive electrode current collector 11. In one embodiment, the positive electrode current collector 11 includes metallic materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum, as well as carbon materials such as carbon cloth and carbon paper. In one embodiment, the positive electrode current collector 11 is a metallic material. In one embodiment, the positive electrode current collector is aluminum.
[0064] The form of the positive electrode current collector 11 is not particularly limited. In some embodiments, when the positive electrode current collector 11 is a metallic material, its form can be a metal foil, a metal cylinder, a metal strip, a metal plate, a metal foil mesh, stamped metal, foamed metal, etc. In some embodiments, when the positive electrode current collector 11 is a carbon material, its form can include, but is not limited to, a carbon plate, a carbon film, a carbon cylinder, etc.
[0065] In one embodiment, the negative electrode active material layer 22 includes a negative electrode active material.
[0066] In this application, there are no particular restrictions on the negative current collector 21, as long as it can achieve the purpose of this application. For example, it can be copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, foamed nickel, foamed copper or composite current collector, etc.
[0067] In one embodiment, the negative electrode active material can be natural graphite, artificial graphite, mesophase microcarbon spheres (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, or spinel-structured lithium titanate Li4Ti5O. 12 At least one of Li-Al alloys and metallic lithium.
[0068] In one embodiment, the negative electrode active material layer 22 further includes a conductive agent and a binder.
[0069] In one embodiment, there is no limitation on the type of conductive agent mentioned in this application (including the conductive agent in the positive electrode active material layer 12 and the negative electrode active material layer 22), and any known conductive agent can be used.
[0070] In one embodiment, the conductive agent (including the conductive agent in the positive electrode active material layer 12 and the negative electrode active material layer 22) includes at least one of carbon materials such as acetylene black, needle coke, carbon nanotubes, graphene, and conductive carbon black.
[0071] In one embodiment, there is no limitation on the type of binder mentioned in this application (including the binder in the positive electrode active material layer 12 and the negative electrode active material layer 22), and any known positive electrode binder can be used.
[0072] In one embodiment, the binder (including the conductive agent in the positive electrode active material layer 12 and the negative electrode active material layer 22) includes at least one of polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, styrene-acrylic latex, pure styrene latex, aromatic polyamide, cellulose (e.g., sodium carboxymethyl cellulose), nitrocellulose, styrene-butadiene rubber, nitrile rubber, fluororubber, isoprene rubber, polybutadiene rubber, ethylene-propylene rubber, styrene-butadiene-styrene block copolymer or its hydrogenation, ethylene-propylene-diene terpolymer, styrene-ethylene-butadiene-ethylene copolymer, styrene-isoprene-styrene block copolymer, syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymer, propylene-α-olefin copolymer, polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene-ethylene copolymer, and acrylics.
[0073] In one embodiment, the diaphragm 3 comprises a porous sheet-like or non-woven material with excellent liquid retention properties. The materials for the resin or glass fiber diaphragm include, but are not limited to, polyolefins, aromatic polyamides, polytetrafluoroethylene, and polyethersulfone.
[0074] In one embodiment, the polyolefin is polyethylene or polypropylene. In some embodiments, the polyolefin is polypropylene. The material of the diaphragm 3 described above can be used alone or in any combination.
[0075] In some embodiments, the secondary battery may include an outer packaging that can be used to encapsulate the aforementioned electrode assembly and electrolyte.
[0076] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. In some embodiments, the outer packaging of the secondary battery can also be a soft pack, such as a pouch-type soft pack. The material of the soft pack can be plastic, and non-limiting examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.
[0077] In some embodiments, the type of electrolyte is not specifically limited. The electrolyte includes an electrolyte salt and an organic solvent, and the specific types of the electrolyte salt and organic solvent are not specifically limited and can be selected according to actual needs. The electrolyte may also include additives, and the type of additives is not particularly limited. These additives can be film-forming additives for the positive and / or negative electrodes, or additives that can improve certain battery performance, such as additives that improve the battery's high or low temperature performance.
[0078] This application does not impose any particular restrictions on the shape of the secondary battery; it can be cylindrical, square, or any other arbitrary shape.
[0079] One embodiment of this application provides an electrical device including the secondary battery described above, wherein the secondary battery serves as the power supply for the electrical device.
[0080] For example, the aforementioned electrical devices may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as 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., but are not limited thereto.
[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.
Claims
1. A secondary battery, characterized in that, The battery includes a wound battery cell, which includes a flat region and a corner region. The wound battery cell includes a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode. The positive electrode includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector. The negative electrode includes a negative current collector and a negative active material layer disposed on at least one surface of the negative current collector. The positive electrode active material layer has a porous coating on the surface of the corner area facing the separator and / or the negative electrode active material layer has a porous coating on the surface of the corner area facing the separator. The porosity of the porous coating is 20-80%.
2. The secondary battery according to claim 1, characterized in that, The porosity of the porous coating is 30-80%.
3. The secondary battery according to claim 1, characterized in that, The adhesion force between the porous coating and the positive electrode active material layer is ≥3N.
4. The secondary battery according to claim 1, characterized in that, The adhesion between the porous coating and the negative electrode active material layer is ≥3N.
5. The secondary battery according to claim 1, characterized in that, The thickness of the porous coating on the corner region facing the separator of the positive electrode active material layer is 10-60% of the thickness of the positive electrode active material layer; and / or The thickness of the porous coating on the corner region of the negative electrode active material layer facing the diaphragm is 10-60% of the thickness of the negative electrode active material layer.
6. The secondary battery according to claim 1, characterized in that, The thickness of the negative electrode active material layer is 50–160 μm; and / or The thickness of the positive electrode active material layer is 40–140 μm.
7. The secondary battery according to claim 1, characterized in that, The thickness of the porous coating on the corner region facing the separator of the positive electrode active material layer is 4–84 μm; and / or The thickness of the porous coating on the corner region of the negative electrode active material layer facing the diaphragm is 5–96 μm.
8. The secondary battery according to claim 1, characterized in that, The thickness of the positive electrode current collector is 5–10 μm.
9. The secondary battery according to claim 1, characterized in that, The thickness of the negative electrode current collector is 3–8 μm.
10. An electrical device, characterized in that, Includes the secondary battery as described in any one of claims 1 to 9.