Batteries and electronic devices

Abstract

This application relates to a battery and an electronic device. The battery includes a negative electrode and an electrolyte; the negative electrode includes a negative current collector and a negative electrode coating disposed on at least one side of the negative current collector; the negative electrode coating includes a silicon-based material; the electrolyte includes a first additive, a second additive, a third additive, and a fourth additive; the first additive includes a fluorosulfonamide compound; the second additive includes an unsaturated carbonate compound; the third additive includes a lithium salt additive; the fourth additive includes a nitrile compound; the battery simultaneously satisfies the following relationships: 0.2≤(A+B+C) / X≤85 (Equation 1); 0.1≤D / (B+C)≤2.4 (Equation 2); 0.03≤C / A≤1.5 (Equation 3). The solution provided in this application enables the battery to exhibit excellent safety performance, high-temperature cycle performance, and low-temperature cycle performance.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more particularly to batteries and electronic devices. Background Technology

[0002] Lithium-ion batteries are widely used in 3C digital products, power tools, aerospace, energy storage, and electric vehicles due to their advantages such as high specific energy, no memory effect, and long cycle life. The rapid development of electronic information technology and consumer products has placed higher demands on the electrochemical performance of lithium-ion batteries.

[0003] Currently, silicon-based anode materials are considered one of the most promising anode materials for next-generation high-energy-density lithium-ion batteries due to their extremely high theoretical specific capacity (approximately 4200 mAh / g), suitable operating voltage, and abundant natural reserves. However, silicon materials face severe challenges in practical applications. The core issue is that silicon undergoes significant volume changes during charging and discharging (expansion rate can reach over 300%), leading to problems such as active material particle rupture, repeated rupture and regeneration of the solid electrolyte interphase (SEI) film, and deterioration of electrode structure stability, severely affecting the battery's cycle performance and safety. Furthermore, the poor conductivity of silicon itself also limits the battery's performance at low temperatures.

[0004] To address these challenges, the industry has generally attempted to improve the structural stability of silicon anodes through nano-sizing and composite methods, and has focused on optimizing electrolyte formulations to construct robust interfacial films. The use of functional additives is crucial in electrolyte optimization. However, single additives often have limited functionality and are insufficient to address the complex failure mechanisms of silicon anodes across multiple interfaces and scales.

[0005] Therefore, developing a multi-component synergistic electrolyte system to solve the problems of interface stability, ion transport kinetics, and compatibility and thermal safety of the silicon anode has become the key to technological breakthroughs in this field. Summary of the Invention

[0006] To address or partially address the problems existing in related technologies, this application provides a battery and electronic device that exhibits excellent safety performance, high-temperature cycle performance, and low-temperature cycle performance.

[0007] The first aspect of this application provides a battery, comprising a negative electrode and an electrolyte; the negative electrode includes a negative current collector and a negative electrode coating disposed on at least one side surface of the negative current collector; the negative electrode coating comprises a silicon-based material;

[0008] The electrolyte includes a first additive, a second additive, a third additive, and a fourth additive; the first additive includes a fluorosulfonamide compound; the second additive includes an unsaturated carbonate compound; the third additive includes a lithium salt additive; and the fourth additive includes a nitrile compound.

[0009] The battery simultaneously satisfies the following relationship:

[0010] 0.2≤(A+B+C) / X≤85 (Equation 1)

[0011] 0.1≤D / (B+C)≤2.4 (Equation 2)

[0012] 0.03≤C / A≤1.5 (Equation 3)

[0013] Wherein, the mass percentage of the first additive in the electrolyte is A; the mass percentage of the second additive in the electrolyte is B; the mass percentage of the third additive in the electrolyte is C; the mass percentage of the fourth additive in the electrolyte is D; and the mass percentage of silicon in the negative electrode coating is X.

[0014] The battery as described in the first aspect, wherein the battery simultaneously satisfies the following relationship:

[0015] 0.38≤(A+B+C) / X≤38 (Equation 4)

[0016] 0.13≤D / (B+C)≤1.88 (Equation 5)

[0017] 0.03≤C / A≤1 Equation 6.

[0018] The battery as described in the first aspect, wherein 3% ≤ A ≤ 70%; and / or, 0.5% ≤ B ≤ 20%.

[0019] The battery as described in the first aspect, wherein 1% ≤ C ≤ 20%; and / or, 1% ≤ D ≤ 15%.

[0020] The battery as described in the first aspect, wherein 1% ≤ X ≤ 100%.

[0021] The battery as described in the first aspect, wherein the first additive comprises at least one of 1,1,1-trifluoro-N,N-dimethylmethanesulfonamide, dimethylaminosulfonyl fluoride, and N,N-diethylaminosulfonyl fluoride; and / or, the second additive comprises vinylene carbonate and / or fluoroethylene carbonate; and / or, the third additive comprises at least one of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorophosphate, lithium difluorooxalateborate, lithium tetrafluoroborate, and lithium dioxoacetoborate; and / or, the fourth additive comprises at least one of 1,3,6-hexanetrionitrile, 1,4-dicyanobutane, butadionitrile, and 1,2-bis(cyanoethoxy)ethane.

[0022] The battery as described in the first aspect, wherein the first additive is 1,1,1-trifluoro-N,N-dimethylmethanesulfonamide; the second additive is vinylene carbonate; the third additive is lithium difluorosulfonylimide; and the fourth additive is 1,3,6-hexanetrionitrile.

[0023] The battery as described in the first aspect, wherein the silicon-based material includes at least one of silicon, silicon-carbon composite, and silicon oxide.

[0024] The battery as described in the first aspect further includes a positive electrode sheet comprising a positive electrode active material, the positive electrode active material comprising one or more of the following: transition metal lithium oxide, lithium iron phosphate, lithium manganese oxide, lithium manganese iron phosphate, and lithium vanadium phosphate; the chemical formula of the transition metal lithium oxide is Li. 1+x Ni y Co z M (1-y-z) O2, where -0.1≤x≤1; 0≤y≤1, 0≤z≤1, and 0≤y+z≤1; where M is selected from one or more of Mg, Zn, Ga, Ba, Al, Fe, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo, and Zr.

[0025] A second aspect of this application provides an electronic device comprising a battery as described in the first aspect.

[0026] The technical solution provided in this application may include the following beneficial effects: On the one hand, the first additive, the second additive, the third additive, and the fourth additive work synergistically: fluorosulfonamide compounds, through fluorine functional groups and sulfonamide functional groups, preferentially reduce to form a rigid SEI film substrate rich in LiF on the negative electrode surface, providing high mechanical strength and thermal stability. At the same time, the sulfonamide groups can capture H+. +The HF purification interface environment; unsaturated carbonate compounds form an elastic SEI outer layer through vinyl polymerization, complementing the rigid LiF layer and enhancing the SEI interface film's tolerance to silicon volume expansion; lithium salt additives not only provide high bulk ionic conductivity, but their decomposition products (such as LiF, Li2S) also contribute to the overall performance. x O y Furthermore, it participates in constructing an interface structure with high ionic conductivity and optimizes ion transport channels; nitrile compounds form a stable CEI film on the positive electrode surface through multiple cyano groups, and capture dissolved transition metal ions through complexation, blocking their destructive chain to the negative electrode SEI; the four work together to form a comprehensive interface protection system of "rigid substrate-elastic buffer-ion transport-positive electrode protection"; on the other hand, by precisely controlling the three core relationships to achieve synergistic performance optimization, it not only ensures better effective protection of silicon materials and positive electrode, but also further improves ion transport rate, ultimately resulting in significant improvement in battery safety performance, high-temperature cycle performance and low-temperature cycle performance.

[0027] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Detailed Implementation

[0028] To facilitate understanding of this application, it will be described in detail below. However, before describing this application in detail, it should be understood that this application is not limited to the specific embodiments described. It should also be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be restrictive.

[0029] Where a numerical range is provided, it should be understood that every intermediate value between the upper and lower limits of the range and any other specified or intermediate value within the specified range is covered within this application. The upper and lower limits of these smaller ranges may be independently included in the smaller range and are also covered within this application, subject to any explicitly excluded limits within the specified range. Where the specified range includes one or two limits, the range excluding any or both of those included limits is also included within this application.

[0030] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. While the methods and materials described herein, or any equivalent methods and materials, may also be used in the implementation or testing of this application, preferred methods and materials are now described.

[0031] Currently, silicon-based anode materials are considered one of the most promising anode materials for next-generation high-energy-density lithium-ion batteries due to their extremely high theoretical specific capacity (approximately 4200 mAh / g), suitable operating voltage, and abundant natural reserves. However, silicon materials face severe challenges in practical applications. The core issue is that silicon undergoes significant volume changes during charging and discharging (expansion rate can reach over 300%), leading to problems such as active material particle rupture, repeated rupture and regeneration of the solid electrolyte interphase (SEI) film, and deterioration of electrode structure stability, severely affecting the battery's cycle performance and safety. Furthermore, the poor conductivity of silicon itself also limits the battery's performance at low temperatures.

[0032] To address these challenges, the industry has generally attempted to improve the structural stability of silicon anodes through nano-sizing and composite methods, and has focused on optimizing electrolyte formulations to build robust interfacial films. The use of functional additives is crucial in electrolyte optimization. However, single additives often have limited functionality and are insufficient to address the complex failure mechanisms of silicon anodes across multiple interfaces and scales. For example, while traditional vinylene carbonate (VC) can form polymeric SEI films, its mechanical strength is insufficient, and excessive use can increase interfacial impedance; fluorosulfonamide compounds can form stable SEI films rich in LiF, but may negatively impact low-temperature performance; and lithium salts such as LiFSI can provide high ionic conductivity, but pose a risk of corroding the current collector.

[0033] To address the aforementioned issues, this application provides a battery comprising a negative electrode and an electrolyte; the negative electrode comprises a negative current collector and a negative electrode coating disposed on at least one side of the negative current collector; the negative electrode coating comprises a silicon-based material; the electrolyte comprises a first additive, a second additive, a third additive, and a fourth additive; the first additive comprises a fluorosulfonamide compound; the second additive comprises an unsaturated carbonate compound; the third additive comprises a lithium salt additive; and the fourth additive comprises a nitrile compound.

[0034] This application does not limit the selection of the negative electrode current collector, which can be selected according to actual needs. For example, copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or composite current collectors can be selected. Preferably, the negative electrode current collector includes copper foil. The negative electrode coating of this application includes a negative electrode active material, which includes a silicon-based material. The silicon-based material of this application is a material including silicon element. This application does not limit the selection of silicon-based material, which can be selected according to actual needs. For example, elemental silicon, silicon-carbon materials, silicon-oxygen materials, etc., can be selected.

[0035] The fluorosulfonamide compounds in this application refer to organic compounds containing both fluorine and sulfonamide functional groups (-S(=O)2N-). The unsaturated carbonate compounds in this application are compounds whose molecules contain carbon-carbon unsaturated bonds (double or triple bonds) in addition to the carbonate functional group (-O-CO-O-). The lithium salt additives in this application refer to compounds containing lithium ions. The nitrile compounds in this application refer to organic compounds containing a cyano group (-CN).

[0036] The battery in this application simultaneously satisfies the following relationship:

[0037] 0.2≤(A+B+C) / X≤85 (Equation 1)

[0038] 0.1≤D / (B+C)≤2.4 (Equation 2)

[0039] 0.03≤C / A≤1.5 (Equation 3)

[0040] The mass percentage of the first additive in the electrolyte is A; the mass percentage of the second additive in the electrolyte is B; the mass percentage of the third additive in the electrolyte is C; the mass percentage of the fourth additive in the electrolyte is D; and the mass percentage of silicon in the negative electrode coating is X.

[0041] The core of setting (A+B+C) / X in Equation 1 is to match sufficient interface protection resources per unit silicon content, preventing insufficient interface protection or excessive additives; for example, (A+B+C) / X can be 0.2, 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 85, etc. The setting of D / (B+C) in Equation 2 aims to balance the resource allocation between positive and negative electrode protection, avoiding interface instability on either side; for example, D / (B+C) can be 0.1, 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, or 2.4, etc. The C / A ratio in Equation 3 is used to optimize the ratio of ion conductivity to structural stability of the interfacial membrane; for example, C / A can be 0.03, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4 or 1.5, etc.

[0042] According to the above-mentioned scheme provided in this application, the battery exhibits excellent safety performance, high-temperature cycle performance, and low-temperature cycle performance. The applicant analyzed the principle behind this and believes the reason lies in the synergistic effect of the first, second, third, and fourth additives: fluorosulfonamide compounds, through fluorine and sulfonamide functional groups, preferentially reduce to form a rigid SEI film substrate rich in LiF on the negative electrode surface, providing high mechanical strength and thermal stability. Simultaneously, the sulfonamide groups can capture H₂. +The HF purification interface environment; unsaturated carbonate compounds polymerize through carbon-carbon unsaturated bonds to form an elastic SEI outer layer, which complements the rigid LiF layer and enhances the SEI interface film's tolerance to silicon volume expansion; lithium salt additives not only provide high bulk ionic conductivity, but their decomposition products (such as LiF, Li2S) also contribute to the overall performance. x O y Furthermore, it participates in constructing an interface structure with high ionic conductivity and optimizes ion transport channels; nitrile compounds form a stable CEI film on the positive electrode surface through multiple cyano groups, and capture dissolved transition metal ions through complexation, blocking their destructive chain to the negative electrode SEI; the four work together to form a comprehensive interface protection system of "rigid substrate-elastic buffer-ion transport-positive electrode protection"; on the other hand, by precisely controlling the three core relationships to achieve synergistic performance optimization, it not only ensures better effective protection of silicon materials and positive electrode, but also further improves ion transport rate, ultimately resulting in significant improvement in battery safety performance, high-temperature cycle performance and low-temperature cycle performance.

[0043] When (A+B+C) / X < 0.2, interface protection is severely insufficient, and silicon particles are directly exposed to the electrolyte, leading to continuous side reactions and a sharp deterioration in cycle performance. When (A+B+C) / X > 85, excessive electrolyte additives form an overly thick interface film, significantly increasing ion migration resistance and causing a decrease in battery cycle performance. When D / (B+C) < 0.1, insufficient positive electrode protection results in an incomplete CEI film, poor thermal safety, and high-temperature cycle degradation. When D / (B+C) > 2.4, excessive nitrile compounds form an overly thick CEI film, increasing kinetic resistance and causing a decrease in battery cycle performance. When C / A < 0.03, severely insufficient ionic conductivity leads to a sharp deterioration in low-temperature performance. When C / A > 1.5, the interface structure is unstable, the risk of side reactions increases, and cycle performance decreases.

[0044] In one specific embodiment, the SEI film of this application includes a layered SEI film bottom layer and an SEI film surface layer, wherein the components of the SEI film bottom layer include LiF and Li2S. x O y The SEI membrane surface layer consists of polycarbonate and Li2S. x O y .

[0045] In one specific embodiment, the CEI membrane of this application comprises LiF, lithium alkoxy, and LiN.

[0046] In one specific implementation, the battery simultaneously satisfies the following relationship:

[0047] 0.38≤(A+B+C) / X≤38 (Equation 4)

[0048] 0.13≤D / (B+C)≤1.88 (Equation 5)

[0049] 0.03≤C / A≤1 Equation 6.

[0050] For example, (A+B+C) / X can be 0.38, 0.5, 1, 5, 10, 15, 20, 25, 30, 35, or 38, etc.; for example, D / (B+C) can be 0.13, 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, or 1.88, etc.; for example, C / A can be 0.03, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1, etc.

[0051] When the battery simultaneously satisfies the above relationship, the synergistic effect of the four additives is better, the rigidity and elasticity of the SEI film are better, the stability of the CEI film is higher, the protection effect of the negative and positive electrodes is better, and the ionic conductivity is greatly improved, thereby significantly improving the high and low temperature cycle performance and thermal shock safety performance of the battery.

[0052] In one specific embodiment, 3% ≤ A ≤ 70%, for example, A can be 3%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, or 70%, etc. When the mass content of the first additive is within the above range, the rigid SEI film substrate formed on the negative electrode surface has better mechanical strength and thermal stability, less acidic substances in the electrolyte, and fewer battery side reactions, thereby further improving the battery's safety performance and high and low temperature cycle performance. If A is less than 3%, the negative electrode interface protection is insufficient, the LiF film formation is incomplete, and the dendrite suppression ability and acid capture effect decrease, leading to an increase in battery side reactions and deteriorating the battery's safety performance and high and low temperature cycle performance; if A is greater than 70%, the excessively thick composite SEI film severely hinders ion migration, affecting the battery's low temperature cycle performance.

[0053] In one specific embodiment, 0.5% ≤ B ≤ 20%, for example, B can be 0.5%, 1%, 2%, 5%, 10%, 15%, or 20%, etc. When the mass percentage of unsaturated carbonate compounds is within the above range, the SEI film has higher elasticity and higher tolerance to the volume expansion of silicon materials, avoiding problems such as cracking and pulverization of the negative electrode active layer, thereby ensuring the safety performance and high and low temperature cycle performance of the battery. If B is less than 0.5%, the formation of the elastic SEI layer is insufficient, and the buffering capacity against silicon volume expansion decreases; if B is greater than 20%, the excessively thick polymer layer leads to excessive interfacial impedance, affecting rate performance.

[0054] In one specific embodiment, 1% ≤ C ≤ 20%, for example, C can be 1%, 2%, 5%, 10%, 15%, or 20%, etc. When the mass percentage of lithium salt additive is within the above range, the bulk and interfacial ionic conductivity is higher, the ion transport channels are better, resulting in higher high and low temperature cycle performance of the battery. If C is less than 1%, the bulk and interfacial ionic conductivity is insufficient; if C is greater than 20%, side reactions are aggravated, which may corrode the current collector and affect thermal safety.

[0055] In one specific embodiment, 1% ≤ D ≤ 15%, for example, D can be 1%, 2%, 5%, 10%, or 15%. When the mass percentage of nitrile compounds is within the above range, the CEI film exhibits better stability, better protects the positive electrode, captures transition metal ions, reduces battery side reactions, and significantly improves the battery's high and low temperature performance and safety performance. If D is less than 1%, the CEI film is incomplete, resulting in insufficient positive electrode protection and a decreased metal ion capture capacity; if D is greater than 15%, an excessively thick positive electrode interface film increases polarization, affecting capacity utilization.

[0056] In one specific embodiment, 1% ≤ X ≤ 100%, for example, X can be 1%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%, etc. When the silicon content is within the above range, silicon-based materials can fully utilize their high capacity advantage in batteries while avoiding excessive volume expansion, thus improving the electrochemical performance of the battery.

[0057] In one specific embodiment, the first additive includes at least one selected from 1,1,1-trifluoro-N,N-dimethylmethanesulfonamide (compound a-1), dimethylaminosulfonyl fluoride (compound a-2), and N,N-diethylaminosulfonyl fluoride (compound a-3). When the first additive is selected from the above compounds, the synergistic effect of the first additive with other additives is better, resulting in higher rigidity, better mechanical strength and thermal stability of the SEI film. Simultaneously, it can better reduce acidic substances in the electrolyte, reduce battery side reactions, thereby improving battery safety and high / low temperature cycle performance.

[0058] In one specific embodiment, the second additive includes vinylene carbonate (compound b-1) and / or fluoroethylene carbonate (compound b-2). When the above-mentioned compounds are selected as the second additive, the second additive can better participate in the synergistic effect, further improve the elasticity of the SEI film, alleviate the volume expansion of silicon to a greater extent, and avoid problems such as cracking and pulverization of the negative electrode active layer, thereby significantly improving the safety performance and high and low temperature cycle performance of the battery.

[0059] In one specific embodiment, the third additive includes at least one of lithium bis(fluorosulfonyl)imide (compound c-1), lithium bis(trifluoromethanesulfonyl)imide (compound c-2), lithium difluorophosphate (compound c-3), lithium difluorooxalate borate (compound c-4), lithium tetrafluoroborate (compound c-5), and lithium dioxoborate (compound c-6). When the third additive is selected as one of the above lithium salts, the battery has a higher lithium-ion transport rate and lower impedance, which helps to further improve the high and low temperature cycle performance of the battery.

[0060] In one specific embodiment, the fourth additive includes at least one of 1,3,6-hexanetrionitrile (compound d-1), 1,4-dicyanobutane (compound d-2), succinic anionylene (compound d-3), and 1,2-bis(cyanoethoxy)ethane (compound d-4). When the fourth additive is selected from the above compounds, it can achieve a better synergistic effect with the first, second, and third additives, resulting in better stability of the CEI film on the positive electrode surface, better protection of the positive electrode, and prevention of the SEI film from being destroyed by transition metal ions dissolved from the positive electrode, thereby obtaining a battery with better safety performance and high and low temperature cycle performance.

[0061] In a preferred embodiment, the first additive is 1,1,1-trifluoro-N,N-dimethylmethanesulfonamide; the second additive is vinylene carbonate; the third additive is lithium difluorosulfonylimide; and the fourth additive is 1,3,6-hexanetrionitrile. These four compounds can exert a better synergistic effect, further improving the stability of the SEI and CEI films, while increasing the lithium-ion transport rate, thereby protecting the positive and negative electrodes of the battery, reducing side reactions, and ultimately enabling the battery to exhibit better safety performance and high and low temperature cycling performance.

[0062] In one specific embodiment, the silicon-based material includes at least one of silicon, silicon-carbon composites, and silicon oxides. When the above-mentioned materials are selected as the silicon-based material, the silicon-based material can fully exert its high-capacity characteristics in the battery, while mitigating the volume expansion problem of the silicon-based material during charge and discharge, thereby ensuring the cycle stability and electrochemical performance of the battery.

[0063] In one specific embodiment, the electrolyte further includes a solvent, which includes at least one selected from ethylene carbonate, propylene carbonate, butenyl carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl propyl carbonate, diphenyl carbonate, methyl acetate, methyl propionate, methyl butyrate, ethyl acetate, propyl acetate, ethyl butyrate, propyl propionate, γ-butyrolactone, 1,3-dioxolane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether. Specifically, by selecting the above-mentioned solvents, the first additive, the second additive, the third additive, and the fourth additive can be dissolved, thereby preparing a stable electrolyte.

[0064] In one specific embodiment, the electrolyte further includes a lithium salt, including lithium hexafluorophosphate and / or lithium bis(trifluoromethanesulfonyl)imide.

[0065] It should be noted that this application does not impose any particular limitation on the preparation method of the electrolyte. Those skilled in the art can prepare the electrolyte using conventional technical means, such as mixing the raw materials evenly according to the specified ratio.

[0066] In one specific embodiment, the negative electrode active material further includes natural graphite, artificial graphite, mesophase micro carbon spheres, hard carbon, soft carbon, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, and spinel-structured lithiated TiO2-Li4Ti5O. 12 At least one of Li-Al alloys.

[0067] In one specific embodiment, the negative electrode coating further includes a negative electrode conductive agent, a negative electrode binder, a thickener, and a solvent. The negative electrode conductive agent includes at least one of carbon materials such as natural graphite, artificial graphite, acetylene black, needle coke, carbon nanotubes, and graphene. The negative electrode binder includes styrene-butadiene latex, etc. The thickener includes CMC, etc. The solvent includes deionized water.

[0068] In one embodiment, the battery further includes a positive electrode sheet, which comprises a positive current collector and a positive electrode coating disposed on at least one surface of the positive current collector. The positive electrode coating comprises a positive electrode active material, which includes one or more of transition metal lithium oxide, lithium iron phosphate, lithium manganese oxide, lithium manganese iron phosphate, and lithium vanadium phosphate; the transition metal lithium oxide has the chemical formula Li. 1+x Ni y Co z M (1-y-z) O2, where -0.1≤x≤1; 0≤y≤1, 0≤z≤1, and 0≤y+z≤1; where M is selected from one or more of Mg, Zn, Ga, Ba, Al, Fe, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo, and Zr.

[0069] The type of positive electrode current collector in this application is not particularly limited; it can be any known material suitable for use as a positive electrode current collector. In one embodiment, the positive electrode current collector 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 is a metallic material.

[0070] In one specific embodiment, the positive electrode coating further includes a positive electrode conductive agent, a positive electrode binder, and a solvent. This application does not limit the type of positive electrode conductive agent; any known conductive agent can be used. In some embodiments, the positive electrode conductive agent mentioned in this application includes at least one of carbon materials such as natural graphite, artificial graphite, acetylene black, needle coke, carbon nanotubes, and graphene.

[0071] This application does not limit the type of positive electrode binder; any known positive electrode binder can be used. In some embodiments, the positive electrode binder includes at least one of polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, and nitrocellulose.

[0072] In the lithium-ion batteries mentioned in this application, a separator is typically provided between the positive and negative electrodes to prevent short circuits. There are no particular restrictions on the material and shape of the separator, as long as it does not significantly impair the effectiveness of this application.

[0073] In one specific embodiment, the diaphragm includes a porous sheet-like or non-woven material with excellent liquid retention properties. The diaphragm includes resin or glass fiber diaphragm materials, which include, but are not limited to, polyolefins, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, etc.

[0074] In one specific embodiment, the lithium-ion battery may include an outer packaging that can be used to encapsulate the aforementioned electrode components and electrolyte.

[0075] In one specific embodiment, the outer packaging of the lithium-ion battery can be a hard shell, such as a hard plastic shell, aluminum shell, or steel shell. The outer packaging of the lithium-ion battery can also be a soft pack, such as a pouch-type soft pack. The material of the soft pack can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0076] This application does not impose any particular restrictions on the shape of the lithium-ion battery; it can be cylindrical, square, or any other arbitrary shape.

[0077] This application also provides an electronic device including the aforementioned lithium-ion battery.

[0078] For example, the aforementioned electronic 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.

[0079] The present invention will be further illustrated by the following examples.

[0080] Example 1

[0081] 1. Preparation of electrolyte

[0082] In an environment with a water content of less than 10 ppm, 1 M lithium hexafluorophosphate was added to propyl propionate, mixed evenly, and then additives were added (the types and amounts of additives are shown in Table 1) to obtain the electrolyte.

[0083] 2. Preparation of the positive electrode sheet

[0084] The positive electrode active material lithium cobalt oxide, the positive electrode conductive agent acetylene black (SuperP) and polyvinylidene fluoride (PVDF) binder are mixed evenly at a mass ratio of 97:1.5:1.5, and then evenly dispersed with 1-methyl-2-pyrrolidone (NMP) to form a uniform positive electrode slurry. The mixed positive electrode slurry is coated on both sides of an aluminum foil current collector, and then baked, rolled, and cut into sheets to obtain the positive electrode sheet.

[0085] 3. Preparation of negative electrode sheet

[0086] Artificial graphite (anode active material), silicon anode, acetylene black (Super P) (conductive agent), CMC (thickener), and SBR (anode binder) (anode binder) are mixed evenly in a mass ratio of 74:20:2:1.2:2.8 and then evenly dispersed with deionized water to form a uniform anode slurry. The mixed slurry is coated on both sides of a copper foil current collector, and then baked, rolled, and cut into sheets to obtain the anode sheet.

[0087] 4. Manufacturing of lithium-ion batteries

[0088] The prepared positive electrode, separator, and negative electrode are stacked in sequence, with the separator in the middle of the positive and negative electrodes. After winding and welding the tabs, a bare cell is obtained. The bare cell is placed in an aluminum-plastic film for liquid injection and encapsulation to obtain a lithium-ion battery.

[0089] Examples 2-45 and Comparative Examples 1-30 are mostly the same as Example 1, except that the types and amounts of additives in the electrolyte and the amount of silicon in the negative electrode active layer are used as shown in Table 1.

[0090] Table 1

[0091]

[0092] Test case

[0093] The following performance tests were performed on the batteries prepared in the examples and comparative examples:

[0094] 1. Thermal shock test

[0095] The lithium-ion batteries prepared in the above embodiments and comparative examples were charged at 25°C at a rate of 1C to the cutoff voltage and a cutoff current of 0.025C. They were then transferred to an oven and heated to 150°C at a rate of 5°C / min and kept constant for 60 minutes. The batteries were considered to have passed the test if they did not catch fire or explode. The number of battery cells tested was 20.

[0096] 2. 45℃ Cyclic Performance Test

[0097] The lithium-ion batteries prepared in the above embodiments and comparative examples were charged and discharged at 45°C at a rate of 1C / 1C within the charge and discharge cutoff voltage range. The discharge capacity of the first cycle was recorded as C1, and the discharge capacity of the Nth cycle was recorded as C2. The capacity of the Nth cycle was divided by the capacity of the first cycle to obtain the cycle capacity retention rate R2 = C2 / C1. The number of cycles of the lithium-ion battery when the cycle capacity retention rate R2 was 70% was recorded.

[0098] 3. 0℃ Cyclic Performance Test

[0099] The lithium-ion batteries prepared in the above embodiments and comparative examples were charged and discharged at 0°C at a rate of 1C / 1C within the charge and discharge cutoff voltage range. The discharge capacity of the first cycle was recorded as Y1, and the discharge capacity of the Nth cycle was recorded as Y2. The capacity of the Nth cycle was divided by the capacity of the first cycle to obtain the cycle capacity retention rate of the Nth cycle, X2 = Y2 / Y1. The cycle number of the lithium-ion battery when the cycle capacity retention rate X2 was 70% was recorded.

[0100] The test results are shown in Table 2.

[0101] Table 2

[0102]

[0103] As can be seen from the test results in Table 2, the overall performance of Examples 1-45 is superior to that of Comparative Examples 1-30. Comparative Example 1, which did not add any functional additives, had only one cell pass the thermal shock test, a cycle life of only 356 cycles at 0°C, and a cycle life of only 345 cycles at 45°C, exhibiting the worst performance. The data comparison demonstrates that the overall performance of the battery is severely inadequate without the synergistic interface protection provided by the four additives.

[0104] Synergistic effect analysis of key parameters:

[0105] 1. Collaborative verification of relational expressions:

[0106] Relationship 1: Interface protection adequacy verification of (A+B+C) / X

[0107] Example 14 (ratio 2.00) exhibited the best overall performance (19 thermal shocks, 787 cycles at 0°C, and 796 cycles at 45°C), demonstrating that the interface protection resources and silicon content were optimally matched at this ratio.

[0108] Comparative Example 26 (ratio 0.05) suffered from a severe deficiency in total additives and an extremely high silicon content, resulting in complete failure of interface protection and a sharp deterioration in cycle performance to approximately 420 cycles.

[0109] Comparative Example 25 (ratio 110) suffered from excessive additives, resulting in an overly thick interfacial film that hindered ion migration and reduced cycle performance to approximately 440 cycles.

[0110] Relationship 2: Verification of the positive and negative electrode protection balance of D / (B+C)

[0111] Example 20 (ratio 0.63) achieved excellent thermal safety (18 passes) and long cycle life (773 cycles at 0°C and 785 cycles at 45°C).

[0112] Comparative Example 28 (ratio 0.03) had poor thermal safety (9 samples passed) and high-temperature cycling degradation due to a severe deficiency of positive electrode protectant D.

[0113] Comparative Example 27 (ratio 10.00) suffered from excessive positive electrode protectant, which resulted in an excessively thick CEI film that increased kinetic resistance and reduced cycle performance to approximately 420 cycles.

[0114] Equation 3: Verification of the interfacial dynamics and stability trade-offs between C and A

[0115] Example 14 (ratio 0.17) achieves a perfect balance between high and low temperature performance and safety.

[0116] Comparative Example 30 (ratio 0.01) exhibited a sharp deterioration in low-temperature performance due to severely insufficient ionic conductivity (only 417 cycles at 0°C).

[0117] Comparative Example 29 (ratio 6.67) experienced a decline in cycling performance to approximately 445 cycles due to an unstable interfacial structure and an increased risk of side reactions.

[0118] 2. Functional validation of a single additive:

[0119] Effect of the content of the first additive (A):

[0120] Examples 1-5 show that when A increases from 3% to 70%, the number of thermal shock passes increases from 16 to 17, and the 45°C cycling performance increases from 638 cycles to 685 cycles, but the 0°C cycling performance decreases from 657 cycles to 612 cycles. This indicates that increasing fluorosulfonamide additives can improve safety and high-temperature performance by forming a LiF-rich SEI film, but excessive amounts will increase interfacial resistance and deteriorate low-temperature performance.

[0121] Effect of the content of the second additive (B):

[0122] Examples 6-11 show that when B increases from 0.5% to 20%, the number of thermal shock passes decreases from 19 to 14, the 0°C cycle performance improves from 648 cycles to 715 cycles, and the 45°C cycle performance improves from 668 cycles to 738 cycles. This indicates that vinylene carbonate can effectively improve cycle performance, but excessive amounts can negatively impact thermal safety due to the exothermic reduction reaction.

[0123] The effect of the content of the third additive (C):

[0124] Examples 12-17 show that when C increases from 1% to 20%, the number of thermal shock passes decreases from 18 to 14, the 0°C cycling performance improves from 618 cycles to 638 cycles, and the 45°C cycling performance improves from 658 cycles to 625 cycles. This indicates that LiFSI can improve cycling performance, but excessive amounts may slightly affect thermal safety due to increased side reactions.

[0125] The effect of the content of the fourth additive (D):

[0126] Examples 18-22 show that when D increases from 1% to 15%, the number of thermal shock passes increases from 14 to 20, the 0°C cycling performance increases from 608 cycles to 668 cycles, and the 45°C cycling performance decreases from 718 cycles to 648 cycles. This indicates that nitrile compounds can significantly improve thermal safety, but excessive amounts may affect high-temperature cycling performance due to an overly thick CEI film.

[0127] 3. Matching silicon content (X) with interface protection resources:

[0128] Examples 23-28 show that when X increases from 1% to 100%, (A+B+C) / X decreases from 38.00 to 0.38, the number of thermal shock passes decreases from 16 to 14, and the cycle performance decreases from approximately 620 cycles to approximately 600 cycles. This verifies the "ABC compensation logic": increasing silicon content must be accompanied by a simultaneous increase in interface protection resources; otherwise, performance will decline across the board.

[0129] 4. The necessity of component integrity:

[0130] When any one of the core components was missing in Comparative Examples 1-5, the performance deteriorated significantly. Comparative Example 1 (complete absence) showed the worst performance; Comparative Example 2 (A only) showed insufficient cycle performance; Comparative Example 3 (B only) showed poor thermal safety; Comparative Example 4 (C only) showed poor overall performance; and Comparative Example 5 (D only) showed poor cycle performance. This demonstrates that all four additives are indispensable, and their synergistic effect is crucial.

[0131] When comparative examples 21-24 used alternative compounds, their performance deteriorated across the board: comparative example 21 (ordinary sulfonamide) lacked F functional groups and could not form a LiF-rich SEI film; the interfacial film formed by comparative example 22 (DTD) lacked sufficient elasticity; comparative example 23 (NaPF6) had low ionic conductivity; and comparative example 24 (isocyanate) lacked cyano functional groups and could not effectively protect the cathode. This highlights the crucial role of the specific molecular structure of this invention in constructing gradient interfacial films.

[0132] 5. Confirmation of the optimal ratio range:

[0133] Examples 3, 14, and 20, within the optimal range of the core relational formula (0.38≤(A+B+C) / X≤38, 0.13≤D / (B+C)≤1.88, 0.03≤C / A≤1), all exhibited the best performance balance (thermal shock ≥18 particles passed, 0℃ cycling ≥628 cycles, 45℃ cycling ≥707 cycles). While comparative examples 25-30 had some parameters within the ABCD range, their performance showed significant shortcomings due to the imbalance of the relational formula, further validating the necessity of this invention to precisely control the synergistic effect through three relational formulas.

[0134] In summary, this application successfully constructed a comprehensive interface protection system of "rigid substrate-elastic buffer-ion transport-positive electrode protection" by precisely controlling the content ratio of four additives and three core relationships. Experimental data fully demonstrate the tight coupling characteristics of the ABCDX system: the absence or imbalance of any component will lead to a significant decrease in performance. Only when all parameters work synergistically within the optimal range can the best balance between high safety and high and low temperature cycling performance of the high-silicon anode battery be achieved.

[0135] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A battery, characterized in that, It includes a negative electrode sheet and an electrolyte; the negative electrode sheet includes a negative electrode current collector and a negative electrode coating disposed on at least one surface of the negative electrode current collector; the negative electrode coating includes a silicon-based material; The electrolyte includes a first additive, a second additive, a third additive, and a fourth additive; the first additive includes a fluorosulfonamide compound; the second additive includes an unsaturated carbonate compound; the third additive includes a lithium salt additive; and the fourth additive includes a nitrile compound. The battery simultaneously satisfies the following relationship: 0.2≤(A+B+C) / X≤85 (Equation 1) 0.1≤D / (B+C)≤2.4 (Equation 2) 0.03≤C / A≤1.5 (Equation 3) Wherein, the mass percentage of the first additive in the electrolyte is A; the mass percentage of the second additive in the electrolyte is B; the mass percentage of the third additive in the electrolyte is C; the mass percentage of the fourth additive in the electrolyte is D; and the mass percentage of silicon in the negative electrode coating is X.

2. The battery according to claim 1, characterized in that, The battery simultaneously satisfies the following relationship: 0.38≤(A+B+C) / X≤38 (Equation 4) 0.13≤D / (B+C)≤1.88 (Equation 5) 0.03≤C / A≤1 Equation 6.

3. The battery according to claim 1, characterized in that, 3% ≤ A ≤ 70%; and / or, 0.5%≤B≤20%。 4. The battery according to claim 1, characterized in that, 1%≤C≤20%; and / or, 1%≤D≤15%。 5. The battery according to claim 1, characterized in that, 1%≤X＜100%。 6. The battery according to any one of claims 1 to 3, characterized in that, The first additive includes at least one of 1,1,1-trifluoro-N,N-dimethylmethanesulfonamide, dimethylaminosulfonyl fluoride, and N,N-diethylaminosulfonyl fluoride; and / or The second additive includes vinylene carbonate and / or fluoroethylene carbonate; and / or, The third additive includes at least one of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorophosphate, lithium difluorooxalate borate, lithium tetrafluoroborate, and lithium dioxoyl borate; and / or, The fourth additive includes at least one of 1,3,6-hexanetrionitrile, 1,4-dicyanobutane, succinic anionylene, and 1,2-bis(cyanoethoxy)ethane.

7. The battery according to claim 6, characterized in that, The first additive is 1,1,1-trifluoro-N,N-dimethylmethanesulfonamide; the second additive is vinylene carbonate; the third additive is lithium difluorosulfonylimide; and the fourth additive is 1,3,6-hexanetrionitrile.

8. The battery according to claim 1, characterized in that, The silicon-based material includes at least one of silicon, silicon-carbon composite, and silicon oxide.

9. The battery according to claim 1, characterized in that, The battery further includes a positive electrode sheet, which comprises a positive electrode active material, including one or more of transition metal lithium oxide, lithium iron phosphate, lithium manganese iron phosphate, and lithium vanadium phosphate; the chemical formula of the transition metal lithium oxide is Li. 1+x Ni y Co z M (1-y-z) O2, where -0.1≤x≤1; 0≤y≤1, 0≤z≤1, and 0≤y+z≤1; where M is selected from one or more of Mg, Zn, Ga, Ba, Al, Fe, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo, and Zr.

10. An electronic device, characterized in that, Includes the battery as described in any one of claims 1 to 9.

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