Battery

Abstract

This invention relates to the field of battery technology, specifically to a battery. The battery includes a positive electrode, a separator, and an electrolyte; the separator includes a carrier layer and a first adhesive layer located on a first surface of the carrier layer, the surface of the first adhesive layer having a plurality of first protrusions; the first adhesive layer faces the positive electrode; the first protrusions include a fluoropolymer; the height h of the first protrusions is 0.2 μm–30 μm; the electrolyte includes organic matter and lithium salt, the organic matter including fluorinated organic matter, including fluorosulfonamide compounds, fluorocarboxylic acid esters, and fluoroethylene carbonate esters; the mass content C of the fluorinated organic matter in the organic matter is 20%–80%; h and C satisfy: C / h is 0.01–3.5. This invention, through the quantitative synergy of the separator surface microstructure and the electrolyte composition, enables the battery to achieve a balance between charge / discharge efficiency, furnace temperature safety performance, and high-temperature performance.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically to a battery. Background Technology

[0002] Lithium-ion batteries are being developed towards higher voltages to improve their energy density. As battery voltage increases, the oxidizability of the positive electrode further increases, making it more prone to oxidation reactions with components in the electrolyte. This can lead to problems such as electrolyte decomposition and gas generation. Furthermore, the crystal structure of the positive electrode active material can undergo irreversible changes, resulting in decreased high-temperature stability and furnace temperature safety of the battery.

[0003] In related technologies, to address the challenges posed by the strong oxidizing properties of high-voltage cathode materials, a common approach is to apply a fluoropolymer (such as polyvinylidene fluoride) coating to the cathode-facing side of the battery separator. This aims to utilize the chemical stability and antioxidant properties of the fluoropolymer to form a physical barrier at the cathode interface, suppressing side reactions such as electrolyte decomposition. However, limitations have been observed in practical applications: while the battery's high-temperature stability and furnace temperature safety are improved, the battery's charge and discharge efficiency deteriorates.

[0004] Therefore, how to balance charge and discharge efficiency, furnace temperature safety, and high-temperature performance in high-voltage battery systems is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the aforementioned problems in the prior art and provide a battery. This battery, through a specific synergistic design of the separator and electrolyte, effectively overcomes the common problems of poor electrolyte wettability and increased interfacial ion transport impedance when using fluoropolymer separators in high-voltage batteries, while ensuring good furnace temperature safety and high-temperature performance. Specifically, this invention employs a separator with fluoropolymer protrusions on the positive electrode side, combined with an electrolyte containing specific fluorinated organic compounds, and strictly controls the ratio of the fluorinated organic compound content C to the protrusion height h (C / h) within the range of 0.01-3.5. This design allows the fluorinated organic compounds in the electrolyte to preferentially adsorb or anchor on the fluoropolymer surface of the separator protrusions through fluorine-fluorine interactions. Thus, on the one hand, it significantly improves the wettability of the electrolyte at the separator-positive electrode interface, reducing interfacial contact impedance; on the other hand, it facilitates the formation of a uniform and stable fluorinated interface protection at the positive electrode interface, improving interfacial ion transport efficiency and chemical stability. Simultaneously, the protrusion structure itself also enhances the mechanical support and structural integrity of the separator at the interface. Therefore, the present invention has produced significant beneficial effects in improving the interface performance, cycle stability and high voltage tolerance of batteries.

[0006] The first aspect of the present invention provides a battery comprising a positive electrode, a separator, and an electrolyte; the separator comprises a carrier layer and a first adhesive layer located on a first surface of the carrier layer, the surface of the first adhesive layer having a plurality of first protrusions; the first adhesive layer facing the positive electrode; the first protrusions comprising a fluoropolymer; the height h of the first protrusions being 0.2 μm-30 μm; the electrolyte comprising an organic compound and a lithium salt, the organic compound comprising a fluorinated organic compound, the fluorinated organic compound comprising a fluorosulfonamide compound, a fluorocarboxylic acid ester, and a fluoroethylene carbonate ester; the mass content C of the fluorinated organic compound in the organic compound being 20%-80%; h, in μm, and h and C satisfying: C / h being 0.01-3.5.

[0007] In the field of high-voltage lithium-ion batteries, a common approach to achieving improved energy density while maintaining high-temperature stability and furnace temperature safety is to coat the positive electrode side of the separator with a layer of fluoropolymer (such as polyvinylidene fluoride, PVDF). The basic principle is to utilize the excellent chemical stability and electrochemical window of the fluoropolymer to form a physical barrier on the positive electrode surface, thereby suppressing the oxidative decomposition of the electrolyte and the structural degradation of the positive electrode material under high voltage. However, in practical applications, it has been found that while this configuration optimizes the chemical stability of the interface, it inevitably impairs the physical wettability and ion transport kinetics, leading to a decrease in battery charge-discharge efficiency. Specifically, during high-voltage cycling, the presence of the fluoropolymer coating causes uneven distribution of the electrolyte at the electrode / separator interface, significantly increasing the interfacial ion transport impedance, and potentially accompanied by gas evolution and accelerated capacity decay.

[0008] Through in-depth analysis, the inventors discovered that the root cause of the above contradictions lies in the following: First, the semi-crystalline fluoropolymer molecules are tightly packed and highly polar, resulting in poor compatibility with conventional weakly polar electrolyte solvents, making it difficult for solvent molecules to effectively wet and penetrate; Second, the flat or microporous coating provides limited storage space and contact points with the electrodes, making it easy for local electrolyte depletion or poor contact to occur during the slight deformation of the electrode sheet during battery charging and discharging.

[0009] Based on the above findings, this invention proposes a different technical approach. Its core concept lies in: structurally designing the surface morphology of the membrane facing the positive electrode and quantitatively correlating it with the content of specific functional components in the electrolyte. This effectively improves the electrolyte wetting uniformity at the interface, reduces ion transport impedance, and enhances the mechanical stability of the interface structure without sacrificing the interfacial protection function. Specifically, as follows: First, fluorosulfonamide compounds, fluorocarboxylic acid esters, and fluoroethylene carbonates all contain fluorine atoms. These fluorine atoms interact with the fluorine-containing first protrusion, and the fluorinated polymer within this protrusion provides adsorption sites for fluorinated organic compounds in the electrolyte. This allows the fluorinated organic compounds to form reversible adsorption sites with the fluorinated polymer in the first protrusion through van der Waals forces, anchoring the fluorinated components at the separator-cathode interface and promoting the uniform distribution of fluorinated organic compounds on the separator and cathode surfaces. Furthermore, when the battery ambient temperature increases or the cathode plate volume changes, the anchoring points slowly release fluorine, directionally generating a robust LiF-rich interface protection on the cathode surface, blocking transition metal dissolution and acid corrosion. In addition, the addition of a specific amount of fluorinated organic compounds to the electrolyte increases the LiF content at the cathode interface, which, in conjunction with the stable structure of the separator, improves the battery's high-temperature cycling and furnace temperature safety.

[0010] Secondly, the first protrusion on the separator surface forms micro-gaps with the positive electrode plate, which can both store sufficient electrolyte and provide buffer space for the expansion of the positive electrode plate: during battery charging and discharging, a small portion of the first protrusion can be compressed and rebounded, slowing down cracking and lithium plating. The fluorinated organic matter in the electrolyte interacts with the fluorinated polymer in the first protrusion, which can enhance the chemical stability and mechanical properties of the separator, preventing the separator from shrinking or deforming during battery charging and discharging.

[0011] Third, in order to further address the issue of balancing interfacial wetting and stability, the height of the first protrusion and the content of fluorinated organic matter in the organic matter were quantitatively matched. This created optimized thermodynamic and kinetic conditions for the adsorption, distribution, and reaction of fluorinated organic matter at the separator-cathode interface, thereby synergistically achieving rapid and uniform wetting of the electrolyte at the interface, significantly reducing the interfacial ion transport impedance, and effectively suppressing interfacial deterioration caused by uneven wetting and side reactions, thus improving the stability and rate performance of the battery at high voltage.

[0012] Through the above technical solution, the present invention has at least the following advantages compared with the prior art: the present invention enables the battery to take into account charging and discharging efficiency, furnace temperature safety performance and high temperature performance through quantitative synergy between the microstructure of the separator surface and the composition of the electrolyte.

[0013] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. Attached Figure Description

[0014] Figure 1The diagram shown is a schematic diagram of the diaphragm structure in an example of the present invention.

[0015] Explanation of reference numerals in the attached drawings: 1-First protrusion; 2-Coating; 3-Substrate layer; 4-Carrier layer; 5-First adhesive layer; 6-Second protrusion Detailed Implementation The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0016] The present invention provides a battery comprising a positive electrode, a separator, and an electrolyte.

[0017] <Septum> In this invention, the separator includes a carrier layer and a first adhesive layer located on a first surface of the carrier layer. The surface of the first adhesive layer has a plurality of first protrusions. The "plurality" refers to the number of first protrusions on the surface of the first adhesive layer being greater than or equal to 2, for example, 2, 6, 15, 30, 50, 80, 100, 150, 200, 500, 700, 1000, 1500, etc. The first adhesive layer faces the positive electrode sheet.

[0018] In this invention, the first protrusion comprises a fluoropolymer.

[0019] In one example, the fluoropolymer includes polymers formed by polymerization of the following monomers: vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, monofluoroethylene, and trifluorochloroethylene.

[0020] In one example, the fluoropolymer includes at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene, polyvinylidene fluoride, polyhexafluoropropylene, fluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, and tetrafluoroethylene-hexafluoropropylene copolymer.

[0021] In this invention, the first protrusion refers to any form of micro or macro raised structure on the surface of the first adhesive layer, including but not limited to: a first protrusion composed of agglomerated fluoropolymer particles, a regular or irregular first protrusion formed by a coating process, a first protrusion composed of particles in the first adhesive layer themselves, or a combination thereof.

[0022] In this invention, the height h of the first protrusion is 0.2 μm-30 μm, for example, 0.2 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 28.5 μm, or 30 μm. The height of the first protrusion refers to the vertical distance from the apex of the first protrusion to the surface of the first adhesive layer. The height of the first protrusion can be tested using conventional methods in the art. For example, a scanning electron microscope (SEM) is used to obtain an SEM image of the membrane cross-section. A 100 μm × 100 μm area is taken from the surface, and the height of 20 first protrusions in this area is measured. This operation is repeated 5 times, and the average of the 5 test results is taken as the height of the first protrusion. If the number of first protrusions in the 100 μm × 100 μm area is less than 20, the 100 μm × 100 μm area is taken again until 20 are measured.

[0023] In one instance, h is 0.2 μm-10 μm.

[0024] In one example, the thickness of the first adhesive layer is 0.2 μm to 5 μm, for example, 0.2 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm or 5 μm.

[0025] In one example, the carrier layer includes a substrate layer and a coating located on at least one surface of the substrate layer. The substrate layer includes at least one of polypropylene, polyethylene, polyimide, polyacrylonitrile, polyurethane, polyvinyl chloride, polyvinyl alcohol, and polyethylene oxide.

[0026] In this invention, the diameter of the orthographic projection of the first protrusion onto the substrate layer is 0.5 μm-20 μm, for example, 0.5 μm, 1 μm, 5 μm, 10 μm, 15 μm, or 20 μm. The diameter of the orthographic projection of the first protrusion onto the substrate layer can be measured using conventional methods in the art. For example, an SEM image of the membrane cross-section can be obtained using SEM scanning. A 100 μm × 100 μm area is taken from the surface, and the diameter of the orthographic projection of 20 first protrusions in this area onto the substrate layer is measured. This operation is repeated 5 times, and the average of the 5 test results is taken as the diameter of the orthographic projection of the first protrusion onto the substrate layer. If the number of first protrusions in the 100 μm × 100 μm area is less than 20, the 100 μm × 100 μm area is continued until 20 protrusions are measured. When the orthographic projection of the first protrusion onto the substrate layer is a regular circle, the diameter of the orthographic projection of the first protrusion onto the substrate layer is the diameter of the regular circle; when the orthographic projection of the first protrusion onto the substrate layer is not a "regular circle", the diameter of the orthographic projection of the first protrusion onto the substrate layer is the equivalent diameter of a circle with the same area as the "irregular circle".

[0027] In this invention, the coverage rate of the first protrusion on the surface of the substrate layer is 5%-60%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, or 60%. The coverage rate of the first protrusion on the surface of the substrate layer can be tested using conventional methods in the art. For example, an SEM image of the membrane cross-section can be obtained using SEM scanning, and a 100μm × 100μm area can be taken from the surface to measure and calculate the coverage rate of the first protrusion within this area; the above operation can be repeated 5 times, and the average value can be taken.

[0028] In one example, the first protrusion has a coverage of 8%-40% on the surface of the substrate layer.

[0029] By controlling the C / h ratio and limiting the coverage of the first protrusion or the diameter of its orthogonal projection onto the substrate layer, a better balance can be achieved between the interaction strength of the fluoropolymer in the first protrusion and the fluorinated organic matter in the organic matter, and the release rate of the fluorine source at the interface. Simultaneously, limiting the coverage of the first protrusion and the diameter of its orthogonal projection onto the substrate layer ensures the spatial density and uniformity of the adsorption sites at the membrane-cathode interface, avoiding localized enrichment or absence of electrolyte due to excessively dense or sparse first protrusions. This macroscopically achieves a more stable and uniform interface wetting and ion transport channel, further consolidating interface stability.

[0030] In one example, the coating comprises organic particles, said organic particles including at least one of melamine, melamine cyanurate, melamine thiocyanate, symmetrical triaminotriazine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 2,4,6-tris(2-pyridyl)triazine, 4-amino-2,6-dihydroxypyrimidine, uracil, cytosine, guanine, 2-mercaptobenzimidazole, 2-mercapto-5-methylbenzimidazole, 2-mercapto-5-methoxybenzimidazole, 2-mercapto-5-ethoxybenzimidazole, 2-mercapto-5-hydroxybenzimidazole, 2-mercapto-5-aminobenzimidazole, and 2-mercapto-5-chlorobenzimidazole.

[0031] Introducing an organic particle coating containing nitrogen-containing heterocyclic organic compounds (such as melamine derivatives) into the carrier layer can, on the one hand, enhance the heat resistance of the separator substrate and improve battery safety by utilizing the high thermal stability and carbonization characteristics of organic particles; on the other hand, the coating including organic particles changes the physicochemical properties of the carrier layer surface, which can optimize the wetting and storage of electrolyte in the separator body. In synergy with the fluorine-containing protrusions on the surface, it improves the overall affinity and retention capacity of the separator for electrolyte, thereby enhancing the interfacial reliability of the battery under high load.

[0032] In one example, the median particle size Dv50 of the organic particles is 0.1 μm-5 μm, for example, 0.1 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, or 5 μm. The median particle size Dv50 of the organic particles can be measured by methods conventional in the art, such as using a laser particle size analyzer.

[0033] In one example, the coating thickness is 0.5 μm to 5 μm, for example, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, or 5 μm. The coating thickness can be measured using methods conventional in the art. For example, an SEM image of the diaphragm cross-section can be obtained using SEM scanning, at least 10 points can be selected on the coating surface, the coating thickness at each point can be measured, and the average value can be taken.

[0034] In one example, the coating at least faces the positive electrode. This means the coating is located on the side of the substrate layer facing the positive electrode.

[0035] In one example, the coating further includes a binder. The binder comprises at least one of the following: polyacrylates, polyvinyl acetate, polyvinyl alcohol, styrene-butadiene rubber, polyvinylidene fluoride-hexafluoropropylene, ethylene-vinyl acetate copolymer, polyvinylpyrrolidone, polyurethane, PVDF, styrene-acrylic latex, polyacrylonitrile, polyacrylic acid, polyurethane-modified polyvinylidene fluoride, or copolymers derived from the above polymers. The binder can prevent the positive electrode active material from shedding powder, form a stable protective film, suppress side reactions between the positive electrode active material and the electrolyte, and improve the stability of the positive electrode interface.

[0036] In one example, the diaphragm further includes a second adhesive layer located on a second surface of the carrier layer. The surface of the second adhesive layer has a plurality of second protrusions. The plurality refers to the fact that the number of second protrusions on the surface of the second adhesive layer is greater than or equal to two. Figure 1 The diagram shows a schematic of the diaphragm structure in an embodiment of the present invention. As can be seen from the diagram, the diaphragm includes a carrier layer 4 and a first adhesive layer 5 located on the first surface of the carrier layer 4. The surface of the first adhesive layer 5 has a plurality of first protrusions 1. The carrier layer 4 includes a substrate layer 3 and a coating layer 2 located on one side surface of the substrate layer 3. The diaphragm also includes a second adhesive layer located on the second surface of the carrier layer 4. The surface of the second adhesive layer has a plurality of second protrusions 6.

[0037] In one example, the second protrusion comprises the fluoropolymer.

[0038] In one example, the height of the second protrusion is 0.2 μm-30 μm, for example, 0.2 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, or 30 μm. The diameter of the orthographic projection of the second protrusion onto the substrate layer is 0.5 μm-20 μm, for example, 0.5 μm, 1 μm, 5 μm, 10 μm, 15 μm, or 20 μm. The coverage of the second protrusion on the surface of the substrate layer is 5%-60%. The height, diameter of the orthographic projection onto the substrate layer, and coverage of the second protrusion on the surface of the substrate layer are the same as those of the first protrusion, and will not be repeated here.

[0039] In one example, the first adhesive layer and the second adhesive layer each independently comprise at least one homopolymer or copolymer of methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, ethylene, styrene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, monofluoroethylene and trifluorochloroethylene, chlorostyrene, fluorostyrene, methylstyrene, acrylic acid, methacrylic acid, methacrylonitrile, and maleic acid.

[0040] Electrolyte In this invention, the electrolyte comprises organic matter and lithium salt. The organic matter refers to all organic substances in the electrolyte other than lithium salt, including organic solvents, organic additives, etc.

[0041] In this invention, the organic compound includes a fluorinated organic compound, which includes fluorosulfonamide compounds, fluorocarboxylic acid esters, and fluoroethylene carbonate (FEC). The mass content (C) of the fluorinated organic compound in the organic compound is 20%-80%, for example, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%.

[0042] In one instance, C is 45%-75%.

[0043] By controlling the mass content (C) of fluorinated organic compounds in the organic matter within the range of 20%-80%, a sufficient but not excessive overall fluorination level in the electrolyte can be ensured to balance polarity and conductivity. Furthermore, by controlling the mass content (C1) of fluorosulfonamide compounds, the mass content (C2) of fluorocarboxylic esters, and the mass content (C3) of FECs in the organic matter, the competitive adsorption and synergistic action mechanisms of different types of fluorinated functional groups at the interface can be precisely controlled. This optimizes the release of the fluorine source and the compositional structure of the LiF interface protection, thereby more effectively reducing interfacial impedance and enhancing the mechanical and chemical stability of the interface protection.

[0044] In this invention, h (in μm) and C satisfy the following: C / h is 0.01-3.5, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3 or 3.5.

[0045] In one instance, C / h is 0.05-2.5.

[0046] In this invention, the content of each substance in the organic compound can be obtained by methods conventional in the art, such as gas chromatography (GC).

[0047] In this invention, the fluorosulfonamide compound includes at least one selected from N,N-dimethylaminosulfonyl fluoride, N,N-diethylaminosulfonyl fluoride, N-methyl-N-ethylaminosulfonyl fluoride, N,N-diisopropylaminosulfonyl fluoride, and N-pyrrolidinyl sulfonyl fluoride.

[0048] In one example, the fluorosulfonamide compound includes N,N-dimethylaminosulfonyl fluoride and / or N,N-diethylaminosulfonyl fluoride.

[0049] In one example, the fluorocarboxylic acid ester includes at least one of ethyl difluoroacetate, methyl pentafluoropropionate, methyl trifluoromethylpropionate, ethyl trifluoroacetate, and 2,2-difluoroethyl acetate (DFEA).

[0050] In one example, the fluorocarboxylic acid ester includes DFEA.

[0051] In one example, the fluorosulfonamide compound has a mass content (C1) of 5%-25% in the organic compound, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 20% or 25%.

[0052] In one example, the fluorocarboxylic acid ester has a mass content of 15%-60% C2 in the organic compound, for example, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 51%, 52%, 55%, 58%, 59% or 60%.

[0053] In one example, the mass content of fluoroethylene carbonate in the organic compound is 5%-20% of C3, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or 20%.

[0054] In one instance, C1+C2 is 20%-70%, for example, 20%, 30%, 40%, 50%, 60% or 70%.

[0055] In this invention, the organic compound further includes a first sulfur-containing compound. The first sulfur-containing compound includes at least one selected from methylene disulfonate (MMDS), 1,3-propanesulfonate lactone (PS), propylene sulfate, vinyl sulfite (ES), vinyl sulfate (DTD), and propylene-1,3-sulfonate lactone (PST). The first sulfur-containing compound can further improve the stability of the SEI film, prevent SEI film cracking and damage, thereby inhibiting the continuous reaction of the electrolyte on the negative electrode surface, reducing the increase in resistance during cycling, and increasing the cycle life of the battery.

[0056] In one instance, the mass content of the first sulfur-containing compound in the organic matter is no more than 3% (C4), for example, 3%, 2.5%, 2%, 1.5%, 1%, 0.5%, 0.4%, 0.3%, 0.2%, or 0.1%.

[0057] In one instance, C4 ranges from 0.3% to 2.5%.

[0058] In one example, the organic compound further includes a second sulfur-containing compound. The second sulfur-containing compound includes at least one of erythritol sulfate (BDTD), pentaerythritol bicyclic sulfate (TDT), and mannitol carbonate sulfate (BDD).

[0059] In one example, the mass content (C5) of the second sulfur-containing compound in the organic matter is 0.5%-4.5%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4% or 4.5%.

[0060] In one instance, C5 is 1%-3%.

[0061] In one example, the C5 / C4 ratio is 0.1-20, for example, 0.1, 0.4, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20. The three-dimensional network structure of -SOC crosslinking formed by the ring-opening of the second sulfur-containing compound under low voltage can alleviate the expansion of the negative electrode to a greater extent and protect the negative electrode interface; while the first sulfur-containing compound can compensate for the defects left by the film formation process of the second sulfur-containing compound, synergistically improving the stability of SEI.

[0062] In one instance, C5 / C4 is 1-3.5.

[0063] In one example, C1 / (C1+C4+C5) is 0.6-0.99, for example, 0.6, 0.7, 0.8, 0.9, or 0.99. When the organic matter simultaneously includes a fluorosulfonamide compound, a first sulfur-containing compound, and a second sulfur-containing compound, it can form an SEI film and a CEI film rich in inorganic components (e.g., LiF, Li2SO3). These films have a dense and stable structure, strong mechanical strength, and can suppress electrode volume changes during battery charging and discharging, thus improving battery stability. The fluorosulfonamide compound can promote the solubility of the first and second sulfur-containing compounds in the electrolyte and promote their formation of the SEI film.

[0064] In one example, the organic compound further includes an ether nitrile additive. The ether nitrile additive includes at least one selected from 1,2,3-tris(2-cyanoethoxy)propane, 1,2,3,4-tetra(2-cyanoethoxy)butane, tetra(2-cyanoethoxymethyl)methane, 1,2,3,4,5-penta(2-cyanoethoxy)pentane, and 1,2,3,4,5,6-hexa(2-cyanoethoxy)hexane. The separator of the present invention has a first protrusion, which leaves a certain gap between the separator and the positive electrode, thereby increasing the liquid retention capacity, improving the wettability of the positive electrode interface, accelerating the adsorption of metal ions in the positive electrode interface by the ether nitrile additive, and further improving the stability of the positive electrode.

[0065] In one example, the ether nitrile additive has a mass content (C6) of 0.5%-3% in the organic compound, for example, 0.5%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5% or 3%.

[0066] In one instance, C6 / C1 is 0.05-0.5, for example, 0.05, 0.06, 0.09, 0.1, 0.15, 0.2, 0.25 or 0.3.

[0067] In one example, the C6 / C5 ratio is 0.2-2, for example, 0.2, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, or 2. The cyano groups of the ether nitrile additive are enriched at the cathode interface through chemisorption; while the CEI film formed by the oxidation of the second sulfur-containing compound can anchor the ether nitrile additive at the cathode interface, thereby further improving the stability of the cathode.

[0068] In one example, the organic compound further includes vinylene carbonate. The mass content of vinylene carbonate in the organic compound (C7) is 0.05%-1%, for example, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or 1%. Vinylene carbonate is preferentially reduced by the solvent, forming a network SEI film through double bond ring-opening polymerization, which particularly improves the interfacial stability of spherical silicon carbon.

[0069] The electrolyte of this battery, in the presence of fluorinated organic matter, introduces and controls the content of sulfur-containing compounds, ether nitrile additives, and vinylene carbonate, and establishes specific ratios between these substances or between them and fluorosulfonamide compounds to further improve the battery's high-temperature stability. The sulfur-containing compounds (a first sulfur-containing compound and a second sulfur-containing compound) preferentially reduce the fluorinated organic matter at the negative electrode, forming a dense and stable SEI bottom film mainly composed of sulfur-containing inorganic matter. The ether nitrile compound selectively adsorbs and reacts with cyano groups at the positive electrode interface through its ether bonds, stabilizing the positive electrode surface and complexing dissolved transition metal ions. Vinylene carbonate polymerizes at the negative electrode to form an elastic polymer layer. By precisely controlling the various content ratios of the above substances, orderly synergy and functional complementarity between the fluorinated component film, the sulfur-containing component film, and the polymer film in terms of time and space are achieved, constructing a multilayer composite electrode interface film with both high ionic conductivity and strong toughness. This improves the battery's high-temperature cycle life and furnace temperature safety while enhancing wetting and transport.

[0070] In one example, the organic compound further includes a non-fluorocarboxylic acid ester. The non-fluorocarboxylic acid ester includes at least one selected from methyl acetate, ethyl acetate, methyl propionate, methyl butyrate, γ-butyrolactone, propyl propionate (PP), ethyl propionate (EP), propyl acetate, and isopropyl acetate.

[0071] In one example, the lithium salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate (LiBF4), lithium bis(oxaloyl)borate (LiBOB), lithium difluorooxaloylborate (LiODFB), lithium difluorodioxaloyl phosphate (LiODFP), lithium difluorophosphate (LiPO2F2), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0072] <Positive Electrode Tablets> In this invention, the positive electrode sheet includes a positive current collector and a positive active coating located on at least one side of the surface of the positive current collector, wherein the positive active coating includes a positive active material. The positive active material includes, for example, at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese aluminum oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, and lithium-rich manganese-based materials.

[0073] Negative electrode film In this invention, the battery further includes a negative electrode sheet. The negative electrode sheet includes a negative current collector and a negative active coating located on at least one side of the surface of the negative current collector. The negative active coating includes a silicon-carbon material; the sphericity of the silicon-carbon material is not less than 0.8. When the sphericity of the silicon-carbon material is not less than 0.8, the silicon-carbon material has a spherical morphology, which can provide a uniform buffer space for the drastic volume changes of silicon particles, reduce internal stress concentration, shorten the ion diffusion path, and accelerate lithium insertion / extraction.

[0074] The sphericity of the silicon-carbon material can be tested using conventional methods in the art. For example, the battery is discharged to 0% SOC, the negative electrode is disassembled and removed, and its cross-section is polished using an argon-ion polisher. The cross-section is then observed using backscatter imaging mode in an SEM device. Silicon-carbon material particles with continuous and smooth contours are found. Any two points on the edge of the particle are connected to form a straight line segment inside the particle. The longest straight line segment within the particle is selected and its length is denoted as Z1. The midpoint of this longest straight line segment is taken, and a straight line is drawn through this midpoint to form a straight line segment with both ends at the edge of the particle. The shortest straight line segment is selected and its length is denoted as Z2. The sphericity of the particle is then Z2 / Z1. At least 10 silicon-carbon material particles are selected, and the average value is taken.

[0075] In one example, the silicon-carbon material comprises a porous carbon matrix and silicon particles located in the pores within the porous carbon matrix.

[0076] It should be noted that the numerical designations such as "first" and "second" in this invention are only used to distinguish different substances or methods of use, and do not represent a difference in order.

[0077] The present invention will be described in detail below through embodiments. The embodiments described herein are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0078] In the following examples, unless otherwise specified, all materials used are commercially available analytical grade.

[0079] The following examples illustrate the battery of the present invention.

[0080] Example 1 The battery is prepared according to the following method: (1) Preparation of electrolyte In an argon glove box with a water content of <0.1ppm and an oxygen content of <0.1ppm, fluorosulfonamide compound (N,N-dimethylaminosulfonyl fluoride), fluorocarboxylic acid ester (DFEA), and PP and propylene carbonate in a mass ratio of 1:1 are mixed evenly. FEC, the first sulfur-containing compound (PS), and lithium salts (LiTFSI at 8% of the total electrolyte mass and lithium hexafluorophosphate at 11% of the total electrolyte mass) are added and mixed to form a homogeneous solution. After passing the physical property test, the electrolyte is obtained. Among them, the mass content of fluorosulfonamide compounds in the organic matter is 8.3% (C1), the mass content of fluorocarboxylic acid esters in the organic matter is 41.3% (C2), the mass content of FEC in the organic matter is 13.6% (C3), the mass content of fluorinated organic compounds in the organic matter is 63.2% (C), the mass content of the first sulfur-containing compound in the organic matter is 0.5% (C4), and the remainder is PP and propylene carbonate; the total mass content of C1+C2 is 49.6%.

[0081] (2) Preparation of positive electrode sheet Lithium cobalt oxide, PVDF, conductive carbon black, and carbon nanotubes were mixed evenly in a mass ratio of 96:2:1.5:0.5. N-methylpyrrolidone (NMP) was added, and the mixture was stirred under vacuum until it formed a uniform and fluid positive electrode active slurry. The positive electrode active slurry was uniformly coated onto the surface of an aluminum foil (12 μm thick). The coated aluminum foil was dried, and then rolled and slit to obtain the positive electrode sheet.

[0082] (3) Preparation of negative electrode sheet Artificial graphite, silicon carbide material, sodium carboxymethyl cellulose, styrene-butadiene rubber, conductive carbon black, and carbon nanotubes were mixed evenly in a mass ratio of 79.5:15:2.5:1.5:1:0.5. Deionized water was added, and the mixture was stirred under vacuum until a homogeneous and fluid negative electrode active slurry was formed. The negative electrode active slurry was uniformly coated onto the surface of a copper foil (6 μm thick). The coated copper foil was air-dried at room temperature, then transferred to an 80°C oven for 10 hours. After cold pressing and slitting, the negative electrode sheet was obtained. The silicon-carbon material includes a porous carbon matrix and silicon particles located in the pores inside the porous carbon matrix; the sphericity of the silicon-carbon material is 0.99, and the mass content of element Si in the silicon-carbon material is 55%.

[0083] (4) Battery preparation The positive electrode sheet, separator, and negative electrode sheet prepared in step (2) are stacked in order to ensure that the separator is between the positive and negative electrode sheets and plays a role in isolation; then, the unfilled core is obtained by winding; the core is placed in the outer packaging foil, and the electrolyte prepared in step (1) is injected into the dried core. After vacuum sealing, standing, formation, shaping, sorting and other processes, a lithium-ion battery is obtained. The separator comprises a substrate layer (a polyethylene film with a thickness of 5 μm), a coating layer (including boehmite with a median particle size Dv50 of 0.5 μm) on one side of the substrate layer, a first adhesive layer (including PVDF) on the outer surface of the coating layer, and a second adhesive layer on the other side of the substrate layer. The outer surface of the first adhesive layer has several first protrusions, each protrusion comprising PVDF, with a height h of 5.3 μm, a diameter of the first protrusion projected onto the substrate layer of 12.8 μm, and a coverage of 25.9% on the surface of the substrate layer. The coating layer has a thickness of 2.5 μm and includes a binder of polyacrylic acid, with the coating facing the positive electrode. The first adhesive layer has a thickness of 2.5 μm and a C / h ratio of 0.12.

[0084] Example 2 To verify the effect of "changes in organic particles in the coating of the diaphragm", the experiment was conducted in accordance with Example 1, except that boehmite with a median particle size Dv50 of 0.5 μm was replaced with melamine cyanurate with a median particle size Dv50 of 1.5 μm.

[0085] Example 3 To verify the effect of "organic matter including a second sulfur-containing compound", the experiment was conducted in accordance with Example 1 (except for PP and propylene carbonate, the contents of all other substances were the same as in Example 1). The difference was that a second sulfur-containing compound (BDD) was added to the electrolyte, wherein the mass content of the second sulfur-containing compound in the organic matter, C5, was 1.6%.

[0086] Example 4 To verify the impact of the change in "C5", the same method was used as in Example 3, except that C5 was 4.2%.

[0087] Example 5 To verify the effect of "the electrolyte including an ether nitrile additive", the experiment was conducted according to Example 1, except that an ether nitrile additive (1,2,3,4,5-penta(2-cyanoethoxy)pentane) was added to the electrolyte, wherein the mass content of the ether nitrile additive in the organic matter was 0.8% (C6).

[0088] Example 6 group This set of embodiments is used to verify the impact of the change of "C6". It is carried out with reference to Embodiment 5, except that C6 is changed, as follows: Example 6a, C6 is 0.5%; Example 6b, C6 is 3%.

[0089] Example 7 To verify the impact of "organic matter including vinylene carbonate", the experiment was conducted in accordance with Example 1, except that vinylene carbonate was added to the electrolyte, wherein the mass content of vinylene carbonate in the organic matter (C7) was 0.2%.

[0090] Example 8 To verify the effect of the change in the "fluorosulfonamide compound" substance, Example 1 was carried out, except that N,N-dimethylaminosulfonyl fluoride was replaced with the same mass of N,N-diisopropylaminosulfonyl fluoride.

[0091] Example 9 group This set of examples is used to verify the impact of changes to "C1, C2, and C3". It is performed in accordance with Example 1, except that C1, C2, and C3 are different, as follows: Example 9a: C1 is 5%, C2 is 60.2%, and C3 is 13.1%; Example 9b: C1 is 25%, C2 is 15.3%, and C3 is 20%; In Example 9c, C1 is 5%, C2 is 15.2%, and C3 is 5.3%.

[0092] Example 10 group Example 10a The battery is prepared according to the following method: (1) Preparation of electrolyte In an argon glove box with a water content of <0.1ppm and an oxygen content of <0.1ppm, fluorosulfonamide compound (N,N-dimethylaminosulfonyl fluoride), fluorocarboxylic acid ester (DFEA), and PP and propylene carbonate in a mass ratio of 1:1 were mixed evenly. FEC, first sulfur-containing compound (PS), second sulfur-containing compound (BDD), ether nitrile additive (1,2,3,4,5-penta(2-cyanoethoxy)pentane), vinylene carbonate, and lithium salt (LiTFSI based on 8% of the total electrolyte mass and lithium hexafluorophosphate based on 11% of the total electrolyte mass) were added and mixed to form a homogeneous solution. After passing the physical property test, the electrolyte was obtained. The organic compounds contained in the following components: fluorosulfonamide compound (C1) with a mass content of 8.1%, fluorocarboxylic acid ester (C2) with a mass content of 25%, FEC (C3) with a mass content of 13.5%, the first sulfur-containing compound (C4) with a mass content of 0.5%, the second sulfur-containing compound (C5) with a mass content of 1.6%, ether nitrile additive (C6) with a mass content of 0.8%, vinylene carbonate (C7) with a mass content of 0.2%, and the remainder being PP and propylene carbonate. The C1+C2 content is 33.1%, the mass content of fluorine-containing organic compounds in organic matter is 46.6%, the C5 / C4 ratio is 3.2, the C1 / (C1+C4+C5) ratio is 0.79, the C6 / C1 ratio is 0.099, and the C6 / C5 ratio is 0.5.

[0093] (2) Preparation of positive electrode sheet Lithium cobalt oxide, PVDF, conductive carbon black, and carbon nanotubes were mixed evenly in a mass ratio of 96:2:1.5:0.5. N-methylpyrrolidone (NMP) was added, and the mixture was stirred under vacuum until it formed a uniform and fluid positive electrode active slurry. The positive electrode active slurry was uniformly coated onto the surface of an aluminum foil (12 μm thick). The coated aluminum foil was dried, and then rolled and slit to obtain the positive electrode sheet.

[0094] (3) Preparation of negative electrode sheet Artificial graphite, silicon carbide material, sodium carboxymethyl cellulose, styrene-butadiene rubber, conductive carbon black, and carbon nanotubes were mixed evenly in a mass ratio of 79.5:15:2.5:1.5:1:0.5. Deionized water was added, and the mixture was stirred under vacuum until a homogeneous and fluid negative electrode active slurry was formed. The negative electrode active slurry was uniformly coated onto the surface of a copper foil (6 μm thick). The coated copper foil was air-dried at room temperature, then transferred to an 80°C oven for 10 hours. After cold pressing and slitting, the negative electrode sheet was obtained. The silicon-carbon material includes a porous carbon matrix and silicon particles located in the pores inside the porous carbon matrix; the sphericity of the silicon-carbon material is 0.99, and the mass content of element Si in the silicon-carbon material is 55%.

[0095] (4) Battery preparation The positive electrode sheet, separator, and negative electrode sheet prepared in step (2) are stacked in order to ensure that the separator is between the positive and negative electrode sheets and plays a role in isolation; then, the unfilled core is obtained by winding; the core is placed in the outer packaging foil, and the electrolyte prepared in step (1) is injected into the dried core. After vacuum sealing, standing, formation, shaping, sorting and other processes, a lithium-ion battery is obtained. The separator comprises a substrate layer (a polyethylene film with a thickness of 5 μm), a coating layer on one side of the substrate layer (including melamine cyanurate with a median particle size Dv50 of 1.5 μm), a first adhesive layer (including PVDF) on the outer surface of the coating layer, and a second adhesive layer on the other side of the substrate layer. The outer surface of the first adhesive layer has several first protrusions, each protrusion comprising PVDF, with a height h of 0.2 μm, a diameter of the first protrusion projected onto the substrate layer of 0.7 μm, and a coverage of 8.6% on the surface of the substrate layer. The coating layer has a thickness of 2.3 μm and includes a binder polyacrylic acid, with the coating facing the positive electrode. The first adhesive layer has a thickness of 2.5 μm and a C / h ratio of 2.33.

[0096] Example 10b The battery is prepared according to the following method: (1) Preparation of electrolyte In an argon glove box with a water content of <0.1ppm and an oxygen content of <0.1ppm, fluorosulfonamide compound (N,N-diethylaminosulfonyl fluoride), fluorocarboxylic acid ester (DFEA), and PP and propylene carbonate in a mass ratio of 1:1 are mixed evenly. FEC, first sulfur-containing compound (PS), second sulfur-containing compound (TDT), ether nitrile additive (1,2,3-tris(2-cyanoethoxy)propane), vinylene carbonate, and lithium salt (LiTFSI based on 8% of the total electrolyte mass and lithium hexafluorophosphate based on 11% of the total electrolyte mass) are added and mixed to form a homogeneous solution. After passing the physical property test, the electrolyte is obtained. Among them, the mass content of fluorosulfonamide compound in organic matter C1 is 5.2%, the mass content of fluorocarboxylic acid ester in organic matter C2 is 50.2%, the mass content of FEC in organic matter C3 is 10.1%, the mass content of the first sulfur-containing compound in organic matter C4 is 0.3%, the mass content of the second sulfur-containing compound in organic matter C5 is 1%, the mass content of ether nitrile additive in organic matter C6 is 2%, the mass content of vinylene carbonate in organic matter C7 is 0.05%, and the remainder is PP and propylene carbonate; The C1+C2 content is 55.4%, the mass content of fluorine-containing organic compounds in organic matter is 65.5%, the C5 / C4 ratio is 3.33, the C1 / (C1+C4+C5) ratio is 0.8, the C6 / C1 ratio is 0.385, and the C6 / C5 ratio is 2.

[0097] (2) Preparation of positive electrode sheet Lithium cobalt oxide, PVDF, conductive carbon black, and carbon nanotubes were mixed evenly in a mass ratio of 96:2:1.5:0.5. N-methylpyrrolidone (NMP) was added, and the mixture was stirred under vacuum until it formed a uniform and fluid positive electrode active slurry. The positive electrode active slurry was uniformly coated onto the surface of an aluminum foil (12 μm thick). The coated aluminum foil was dried, and then rolled and slit to obtain the positive electrode sheet.

[0098] (3) Preparation of negative electrode sheet Artificial graphite, silicon carbide material, sodium carboxymethyl cellulose, styrene-butadiene rubber, conductive carbon black, and carbon nanotubes were mixed evenly in a mass ratio of 79.5:15:2.5:1.5:1:0.5. Deionized water was added, and the mixture was stirred under vacuum until a homogeneous and fluid negative electrode active slurry was formed. The negative electrode active slurry was uniformly coated onto the surface of a copper foil (6 μm thick). The coated copper foil was air-dried at room temperature, then transferred to an 80°C oven for 10 hours. After cold pressing and slitting, the negative electrode sheet was obtained. The silicon-carbon material includes a porous carbon matrix and silicon particles located in the pores inside the porous carbon matrix; the sphericity of the silicon-carbon material is 0.91, and the mass content of element Si in the silicon-carbon material is 55%.

[0099] (4) Battery preparation The positive electrode sheet, separator, and negative electrode sheet prepared in step (2) are stacked in order to ensure that the separator is between the positive and negative electrode sheets and plays a role in isolation; then, the unfilled core is obtained by winding; the core is placed in the outer packaging foil, and the electrolyte prepared in step (1) is injected into the dried core. After vacuum sealing, standing, formation, shaping, sorting and other processes, a lithium-ion battery is obtained. The separator comprises a substrate layer (a polyethylene film with a thickness of 5 μm), a coating layer on one side of the substrate layer (including melamine cyanurate with a median particle size Dv50 of 0.1 μm), a first adhesive layer (including polytetrafluoroethylene) on the outer surface of the coating layer, and a second adhesive layer on the other side of the substrate layer. The outer surface of the first adhesive layer has several first protrusions, each of which is made of polytetrafluoroethylene. The height h of the first protrusion is 1.8 μm, the diameter of the first protrusion projected onto the substrate layer is 2.6 μm, and the coverage of the first protrusion on the surface of the substrate layer is 25.5%. The coating layer has a thickness of 0.7 μm and includes a binder, polyacrylic acid, with the coating facing the positive electrode. The first adhesive layer has a thickness of 4.5 μm and a C / h ratio of 0.36.

[0100] Example 10c The battery is prepared according to the following method: (1) Preparation of electrolyte In an argon glove box with a water content of <0.1ppm and an oxygen content of <0.1ppm, fluorosulfonamide compound (N,N-dimethylaminosulfonyl fluoride), fluorocarboxylic acid ester (DFEA), and PP and propylene carbonate in a mass ratio of 1:1 are mixed evenly. FEC, first sulfur-containing compound (PS), second sulfur-containing compound (BDTD), ether nitrile additive (1,2,3,4,5-penta(2-cyanoethoxy)pentane), vinylene carbonate, and lithium salt (LiTFSI based on 8% of the total electrolyte mass and lithium hexafluorophosphate based on 11% of the total electrolyte mass) are added and mixed to form a homogeneous solution. After passing the physical property test, the electrolyte is obtained. Among them, the mass content of fluorosulfonamide compound in organic matter C1 is 12.6%, the mass content of fluorocarboxylic acid ester in organic matter C2 is 30.5%, the mass content of FEC in organic matter C3 is 15.2%, the mass content of the first sulfur-containing compound in organic matter C4 is 2.5%, the mass content of the second sulfur-containing compound in organic matter C5 is 2.9%, the mass content of ether nitrile additive in organic matter C6 is 1.2%, the mass content of vinylene carbonate in organic matter C7 is 1%, and the remainder is PP and propylene carbonate; The C1+C2 content is 43.1%, the mass content of fluorine-containing organic compounds in organic matter is 58.3%, the C5 / C4 ratio is 1.16, the C1 / (C1+C4+C5) ratio is 0.7, the C6 / C1 ratio is 0.095, and the C6 / C5 ratio is 0.41.

[0101] (2) Preparation of positive electrode sheet Lithium cobalt oxide, PVDF, conductive carbon black, and carbon nanotubes were mixed evenly in a mass ratio of 96:2:1.5:0.5. N-methylpyrrolidone (NMP) was added, and the mixture was stirred under vacuum until it formed a uniform and fluid positive electrode active slurry. The positive electrode active slurry was uniformly coated onto the surface of an aluminum foil (12 μm thick). The coated aluminum foil was dried, and then rolled and slit to obtain the positive electrode sheet.

[0102] (3) Preparation of negative electrode sheet Artificial graphite, silicon carbide material, sodium carboxymethyl cellulose, styrene-butadiene rubber, conductive carbon black, and carbon nanotubes were mixed evenly in a mass ratio of 79.5:15:2.5:1.5:1:0.5. Deionized water was added, and the mixture was stirred under vacuum until a homogeneous and fluid negative electrode active slurry was formed. The negative electrode active slurry was uniformly coated onto the surface of a copper foil (6 μm thick). The coated copper foil was air-dried at room temperature, then transferred to an 80°C oven for 10 hours. After cold pressing and slitting, the negative electrode sheet was obtained. The silicon-carbon material includes a porous carbon matrix and silicon particles located in the pores inside the porous carbon matrix; the sphericity of the silicon-carbon material is 0.85, and the mass content of element Si in the silicon-carbon material is 55%.

[0103] (4) Battery preparation The positive electrode sheet, separator, and negative electrode sheet prepared in step (2) are stacked in order to ensure that the separator is between the positive and negative electrode sheets and plays a role in isolation; then, the unfilled core is obtained by winding; the core is placed in the outer packaging foil, and the electrolyte prepared in step (1) is injected into the dried core. After vacuum sealing, standing, formation, shaping, sorting and other processes, a lithium-ion battery is obtained. The separator comprises a substrate layer (a polyethylene film with a thickness of 5 μm), a coating layer (including uracil with a median particle size Dv50 of 2.6 μm) on one side of the substrate layer, a first adhesive layer (including PVDF) on the outer surface of the coating layer, and a second adhesive layer on the other side of the substrate layer. The outer surface of the first adhesive layer has several first protrusions, each of which includes PVDF. The height h of the first protrusion is 9.5 μm, the diameter of the first protrusion projected onto the substrate layer is 19.6 μm, and the coverage of the first protrusion on the surface of the substrate layer is 38.8%. The coating layer has a thickness of 4.6 μm and includes a binder, polyacrylic acid, with the coating facing the positive electrode. The first adhesive layer has a thickness of 0.3 μm and a C / h ratio of 0.06.

[0104] Example 11 This was used to verify the effect of the change in "C / h". It was carried out with reference to Example 10b, except that the diaphragm of Example 10a was used, with a C / h of 3.28.

[0105] Example 12 group This set of examples is used to verify the impact of the change in "C5 / C4". It is performed in accordance with Example 10a, except that C4 and C5 are changed, as follows: Example 12a, C4 is 0.3%, C5 is 3%, C5 / C4 is 10; Example 12b: C4 is 2.5%, C5 is 1%, and C5 / C4 is 0.4.

[0106] Example 13 group This set of embodiments is used to verify the impact of changing the height h of the first protrusion.

[0107] This set of embodiments is based on Embodiment 1, except that h is changed, as follows: In Example 13a, the height h of the first protrusion is 15.9 μm; In Example 13b, the height h of the first protrusion is 28.3 μm.

[0108] Comparative Example 1 The procedure was carried out in accordance with Example 1, except that the first protrusion did not include a fluoropolymer, but included polymethyl methacrylate.

[0109] Comparative Example 2 The procedure was carried out in accordance with Example 1, except that the fluorosulfonamide compound was replaced with the same mass of 2,2,2-trifluoro-N,N-dimethylacetamide.

[0110] Comparative Example 3 The procedure was carried out in accordance with Example 1, except that no fluorosulfonamide compound was added to the electrolyte.

[0111] Comparative Example 4 The procedure was carried out in accordance with Example 1, except that DFEA was not added to the electrolyte.

[0112] Test case (1) Furnace temperature safety test The batteries prepared in the examples and comparative examples were fully charged at room temperature (25℃±2℃), and then placed horizontally in an oven. The oven was heated to 135℃ at a heating rate of (5±2)℃ / min and placed at this temperature for 60 min. After standing for 2 h, the battery status was observed. When the battery did not leak, catch fire, or explode, it was considered to have passed. Ten batteries were tested in each example, and the results were expressed as x / 10, where x is the number of batteries that passed the test. The results are recorded in Table 1.

[0113] (2) High temperature cycling test The batteries prepared in the examples and comparative examples were placed in an oven at a temperature of 45℃±2℃ and charged to 4.53V at a constant current density of 1.5C (cutoff current of 0.25C). After the batteries were fully charged, they were left to stand for 5 minutes and then discharged at a constant current density of 0.5C (cutoff voltage of 3.0V). The discharge capacity was recorded as the initial capacity Q1. When the cycle reached 700 cycles, the discharge capacity Q2 of the battery was recorded. The capacity retention rate (%) = (Q2 / Q1)×100%. The results are recorded in Table 1.

[0114] (3) Charge and discharge efficiency test The batteries prepared in the examples and comparative examples were placed at room temperature (25℃±2℃) and charged to 4.53V at a constant current density of 1.5C. They were then discharged to 3.0V at a constant current density of 0.5C, and the discharge capacity was recorded as the initial capacity Q0. Then, the batteries were charged to 4.53V at a constant current density of 1.5C and then discharged at a rate of 5C, and the capacity Q3 was recorded. The capacity retention rate at 5C (%) is calculated as (Q3 / Q0)×100%.

[0115] Table 1 As can be seen from Table 1, the battery of the present invention, compared with the comparative example, can balance charge and discharge efficiency, furnace temperature safety performance and high temperature performance.

[0116] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A battery, characterized by, The battery includes a positive electrode, a separator, and an electrolyte; The separator includes a carrier layer and a first adhesive layer located on a first surface of the carrier layer, the surface of the first adhesive layer having a plurality of first protrusions; the first adhesive layer faces the positive electrode sheet. The first protrusion comprises a fluoropolymer; the height h of the first protrusion is 0.2 μm-30 μm; The electrolyte comprises organic matter and lithium salt, wherein the organic matter includes fluorinated organic matter, which includes fluorosulfonamide compounds, fluorocarboxylic acid esters, and fluoroethylene carbonate esters; the mass content (C) of the fluorinated organic matter in the organic matter is 20%-80%. h is in μm, and h and C satisfy: C / h is 0.01-3.

5.

2. The battery of claim 1, wherein, C / h is 0.05-2.5; And / or, the fluoropolymer includes polymers formed by polymerization of the following monomers: vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, monofluoroethylene, and trifluorochloroethylene; Preferably, the fluoropolymer includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl fluoride, polyhexafluoropropylene, fluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, and tetrafluoroethylene-hexafluoropropylene copolymer.

3. The battery according to claim 1 or 2, wherein The carrier layer includes a substrate layer and a coating located on at least one surface of the substrate layer. The coating includes organic particles, which include at least one of melamine, melamine cyanurate, melamine trithiocyanate, symmetrical triaminotriazine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 2,4,6-tris(2-pyridyl)triazine, 4-amino-2,6-dihydroxypyrimidine, uracil, cytosine, guanine, 2-mercaptobenzimidazole, 2-mercapto-5-methylbenzimidazole, 2-mercapto-5-methoxybenzimidazole, 2-mercapto-5-ethoxybenzimidazole, 2-mercapto-5-hydroxybenzimidazole, 2-mercapto-5-aminobenzimidazole, and 2-mercapto-5-chlorobenzimidazole. Preferably, the median particle size Dv50 of the organic particles is 0.1 μm-5 μm; Preferably, the thickness of the coating is 0.5 μm-5 μm; Preferably, the coating faces at least the positive electrode sheet; Preferably, the first protrusion has a coverage rate of 5%-60% on the surface of the substrate layer; more preferably, it has a coverage rate of 8%-40%. Preferably, the diameter of the orthographic projection of the first protrusion onto the substrate layer is 0.5μm-20μm.

4. The battery according to claim 1 or 2, wherein C is 45%-75%; And / or, the fluorosulfonamide compound comprises at least one selected from N,N-dimethylaminosulfonyl fluoride, N,N-diethylaminosulfonyl fluoride, N-methyl-N-ethylaminosulfonyl fluoride, N,N-diisopropylaminosulfonyl fluoride, and N-pyrrolidinyl sulfonyl fluoride; preferably, the fluorosulfonamide compound comprises N,N-dimethylaminosulfonyl fluoride and / or N,N-diethylaminosulfonyl fluoride; And / or, the fluorocarboxylic acid esters include 2,2-difluoroethyl acetate.

5. The battery of claim 1 or 2, wherein, The mass content (C1) of the fluorosulfonamide compound in the organic matter is 5%-25%; And / or, the fluorocarboxylic acid ester has a C2 content of 15%-60% in the organic compound; And / or, the mass content of fluoroethylene carbonate in the organic compound is 5%-20% (C3); And / or, C1+C2 is 20%-70%.

6. The battery of claim 1 or 2, wherein, The organic compound further includes a first sulfur-containing compound; the first sulfur-containing compound includes at least one of methylene disulfonate, 1,3-propane sulfonate lactone, propylene sulfate, vinyl sulfite, vinyl sulfate, and propylene-1,3-sulfonate lactone. Preferably, the mass content (C4) of the first sulfur-containing compound in the organic matter is 0.3%-2.5%.

7. The battery of claim 6, wherein, The organic compound also includes a second sulfur-containing compound, which includes at least one of erythritol sulfate, pentaerythritol bicyclic sulfate, and mannitol carbonate sulfate. Preferably, the mass content (C5) of the second sulfur-containing compound in the organic matter is 0.5%-4.5%; More preferably, the electrolyte satisfies the following condition: C1 / (C1+C4+C5) is 0.6-0.99; More preferably, the electrolyte satisfies the following condition: C5 / C4 is 0.1-20.

8. The battery of claim 1 or 2, wherein, The organic compound further includes ether nitrile additives; the ether nitrile additives include at least one selected from 1,2,3-tris(2-cyanoethoxy)propane, 1,2,3,4-tetra(2-cyanoethoxy)butane, tetra(2-cyanoethoxymethyl)methane, 1,2,3,4,5-penta(2-cyanoethoxy)pentane and 1,2,3,4,5,6-hexa(2-cyanoethoxy)hexane; Preferably, the ether nitrile additive has a C6 content of 0.5%-3% in the organic compound; More preferably, the electrolyte satisfies the following condition: C6 / C1 is 0.05-0.5; More preferably, the organic compound further includes a second sulfur-containing compound, the second sulfur-containing compound having a mass content of C5 in the organic compound, and the electrolyte satisfying that the C6 / C5 ratio is 0.2-2.

9. The battery of claim 1 or 2, wherein, The organic compound also includes vinylene carbonate; the mass content of vinylene carbonate in the organic compound is 0.05%-1% (C7).

10. The battery of claim 1 or 2, wherein, The battery further includes a negative electrode sheet; the negative electrode sheet includes a negative current collector and a negative active coating located on at least one side of the surface of the negative current collector, the negative active coating including a silicon-carbon material; the sphericity of the silicon-carbon material is not less than 0.8.

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