A lithium-ion battery

Abstract

To overcome the problem of insufficient high-temperature cycle performance in existing lithium-ion batteries, this invention provides a lithium-ion battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode includes a positive electrode current collector with a conductive coating on its surface and a positive electrode material layer disposed on the positive electrode current collector. The non-aqueous electrolyte includes a non-aqueous organic solvent, a lithium salt, and an additive. The additive includes a compound represented by structural formula 1. The lithium-ion battery satisfies the following condition: and 2.4 ≤ M. A ≤3.6, 0.1≤W A ≤5, 0.1≤d≤10, 3.3≤c≤3.8. The lithium-ion battery provided by this invention can effectively improve high-temperature cycling and storage performance.

Description

Technical Field

[0001] This invention belongs to the field of secondary battery technology, specifically relating to a lithium-ion battery. Background Technology

[0002] Lithium-ion rechargeable batteries possess advantages such as high cycle life, wide operating temperature range, high energy and power density, and no memory effect, leading to their widespread application in digital, power, and energy storage fields. As their applications become increasingly diversified, the performance requirements for lithium-ion rechargeable batteries are also rising, such as requiring longer-lasting high-temperature performance. This, in turn, places corresponding demands on the development of high-end electrolytes.

[0003] Under high-temperature conditions, ternary cathode materials in lithium-ion secondary batteries, especially those with a nickel content ≥70%, are prone to catalyzing electrolyte decomposition, releasing lattice oxygen. In addition to lithium and nickel mixing, the materials are susceptible to microcracks, further triggering continuous electrolyte repair of the cathode interface. During this process, the cathode particles gradually lose adhesion to the current collector, leading to irreversible capacity loss. Therefore, it is necessary to construct a more robust and resilient interfacial film on the surface of the ternary material particles to reduce side reactions and microcrack formation, thereby improving the battery's high-temperature performance. Summary of the Invention

[0004] To address the problem of insufficient high-temperature cycle performance in existing lithium-ion batteries, this invention provides a lithium-ion battery.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] This invention provides a lithium-ion battery, comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode includes a positive electrode current collector with a conductive coating on its surface and a positive electrode material layer disposed on the positive electrode current collector. The non-aqueous electrolyte includes a non-aqueous organic solvent, a lithium salt, and an additive. The additive includes a compound represented by structural formula 1.

[0007]

[0008] Where n is 0 or 1, A is selected from C or O, and X is selected from... R1 and R2 are each independently selected from H, R1 and R2 are not both selected from H, and X, R1 and R2 contain at least one sulfur atom;

[0009] The lithium-ion battery meets the following conditions:

[0010] And 2.4≤M A ≤3.6, 0.1≤W A≤5, 0.1≤d≤10, 3.3≤c≤3.8;

[0011] Among them, M A This refers to the liquid retention capacity of the non-aqueous electrolyte, expressed in g / Ah.

[0012] W A The mass percentage of the compound shown in structural formula 1 in the non-aqueous electrolyte is expressed in %.

[0013] d represents the thickness of the conductive coating, in μm;

[0014] c is the compaction density of the positive electrode material layer, in g / cm³. 3 .

[0015] Optionally, the lithium-ion battery meets the following conditions:

[0016]

[0017] Optionally, the liquid retention capacity M of the non-aqueous electrolyte A It ranges from 2.6 to 3.2 g / Ah.

[0018] Optionally, the mass percentage W of the compound represented by structural formula 1 in the non-aqueous electrolyte A It ranges from 0.1% to 2%.

[0019] Optionally, the thickness d of the conductive coating is 0.1 to 5 μm.

[0020] Optionally, the compaction density c of the positive electrode material layer is 3.4–3.6 g / cm³. 3 .

[0021] Optionally, the conductive coating is a conductive carbon layer comprising carbon material.

[0022] The carbon material includes at least one of carbon nanotubes, carbon fibers, and conductive carbon black.

[0023] Optionally, the compound represented by structural formula 1 is selected from at least one of the following compounds:

[0024]

[0025]

[0026]

[0027] Optionally, the additive further includes at least one of cyclic sulfate compounds, sulfonyl lactone compounds, cyclic carbonate compounds, phosphate compounds, borate compounds, and nitrile compounds;

[0028] Based on the total mass of the non-aqueous electrolyte as 100%, the content of the additive is 0.01% to 30%.

[0029] Preferably, the cyclic sulfate compound is selected from vinyl sulfate, propylene sulfate, methyl vinyl sulfate, etc. At least one of them;

[0030] The sulfonyl lactone compound is selected from at least one of 1,3-propanesulfonyl lactone, 1,4-butanesulfonyl lactone, and 1,3-propenesulfonyl lactone.

[0031] The cyclic carbonate compounds are selected from vinylene carbonate, ethylene ethylene carbonate, methylene carbonate, fluoroethylene carbonate, trifluoromethyl ethylene carbonate, difluoroethylene carbonate, or other compounds with the following structure.

[0032] At least one of the compounds shown in Formula 2,

[0033]

[0034] In structural formula 2, R 21 R 22 R 23 R 24 R 25 R 26 Each is independently selected from one of the following: hydrogen atom, halogen atom, or C1-C5 group;

[0035] The phosphate ester compound is selected from at least one of tris(trimethylsilane) phosphate, tris(trimethylsilane) phosphite, or the compound shown in structural formula 3:

[0036]

[0037] In structural formula 3, R 31 R 32 R 33 Each is independently selected from C1-C5 saturated hydrocarbon groups, unsaturated hydrocarbon groups, halohydrocarbon groups, and -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and R 31 R 32 R 33 At least one of them is an unsaturated hydrocarbon group;

[0038] The borate ester compound is selected from at least one of tris(trimethylsilane)borate ester and tris(triethylsilane)borate ester;

[0039] The nitrile compound is selected from at least one of butadionitrile, glutaronitrile, ethylene glycol bis(propionitrile) ether, hexanetrionitrile, adiponitrile, heptanonitrile, octadionitrile, nonadionitrile, and sebaconitrile.

[0040] The lithium-ion battery provided by the present invention uses a compound shown in structural formula 1 as an additive to participate in the formation of an interface film on the surface of the positive electrode material layer. The inventors discovered through experiments that when the liquid retention M of the non-aqueous electrolyte... A The mass percentage W of the compound represented by structural formula 1 in the non-aqueous electrolyte. A The thickness d of the conductive coating and the compaction density c of the positive electrode material layer satisfy the following condition. And 2.4≤M A ≤3.6, 0.1≤W A When the values ​​are ≤5, 0.1≤d≤10, and 3.3≤c≤3.8, the resulting lithium-ion battery exhibits excellent high-temperature cycle performance and high-temperature storage performance. This is because a conductive coating is applied to the surface of the positive electrode current collector, giving it good static conductivity. By controlling the thickness of the conductive coating, the micro-current of the positive electrode material layer can be balanced, allowing the compound shown in Structural Formula 1 to participate more fully in forming a complete interface film on the surface of the positive electrode material layer. At the same time, the compaction density of the positive electrode material layer, the liquid retention of the non-aqueous electrolyte, and the mass percentage of the compound shown in Structural Formula 1 in the non-aqueous electrolyte directly affect the sufficiency of the contact between the compound shown in Structural Formula 1 and the surface of the positive electrode material layer, as well as the consumption decomposition rate and diffusion efficiency of the compound shown in Structural Formula 1 on the surface of the positive electrode material layer during the formation stage. By correlating the above parameters, the compound shown in Structural Formula 1 can form a film with sufficient density, high thermal stability, and low impedance, thereby effectively improving the high-temperature cycle and storage performance of the lithium-ion battery. Detailed Implementation

[0041] To make the technical problems solved, technical solutions, and beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0042] This invention provides a lithium-ion battery, comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode includes a positive electrode current collector with a conductive coating on its surface and a positive electrode material layer disposed on the positive electrode current collector. The non-aqueous electrolyte includes a non-aqueous organic solvent, a lithium salt, and an additive. The additive includes a compound represented by structural formula 1.

[0043]

[0044] Where n is 0 or 1, A is selected from C or O, and X is selected from... R1 and R2 are each independently selected from H, R1 and R2 are not both selected from H, and X, R1 and R2 contain at least one sulfur atom;

[0045] The lithium-ion battery meets the following conditions:

[0046] And 2.4≤M A ≤3.6, 0.1≤W A ≤5, 0.1≤d≤10, 3.3≤c≤3.8;

[0047] Among them, M A This refers to the liquid retention capacity of the non-aqueous electrolyte, expressed in g / Ah.

[0048] W A The mass percentage of the compound shown in structural formula 1 in the non-aqueous electrolyte is expressed in %.

[0049] d represents the thickness of the conductive coating, in μm;

[0050] c is the compaction density of the positive electrode material layer, in g / cm³. 3 .

[0051] The lithium-ion battery uses the compound shown in structural formula 1 as an additive to participate in the formation of the interface film on the surface of the positive electrode material layer. The inventors discovered through experiments that when the liquid retention M of the non-aqueous electrolyte... A The mass percentage W of the compound represented by structural formula 1 in the non-aqueous electrolyte. A The thickness d of the conductive coating and the compaction density c of the positive electrode material layer satisfy the following condition. And 2.4≤M A ≤3.6, 0.1≤W A When the values ​​are ≤5, 0.1≤d≤10, and 3.3≤c≤3.8, the resulting lithium-ion battery exhibits excellent high-temperature cycle performance and high-temperature storage performance. This is because a conductive coating is applied to the surface of the positive electrode current collector, giving it good static conductivity. By controlling the thickness of the conductive coating, the micro-current of the positive electrode material layer can be balanced, allowing the compound shown in Structural Formula 1 to participate more fully in forming a complete interface film on the surface of the positive electrode material layer. At the same time, the compaction density of the positive electrode material layer, the liquid retention of the non-aqueous electrolyte, and the mass percentage of the compound shown in Structural Formula 1 in the non-aqueous electrolyte directly affect the sufficiency of the surface contact between the compound shown in Structural Formula 1 and the positive electrode material layer, as well as the consumption decomposition rate and diffusion efficiency of the compound shown in Structural Formula 1 on the surface of the positive electrode material layer during the formation stage. By correlating the above parameters, the compound shown in Structural Formula 1 can form a film with sufficient density, high thermal stability, and low impedance, thereby effectively improving the high-temperature cycle and storage performance of the lithium-ion battery.

[0052] In some embodiments, when n is 0, the compound represented by structural formula 1 is:

[0053]

[0054] Where A is selected from C or O, and X is selected from... R1 and R2 are each independently selected from H, R1 and R2 are not both selected from H, and X, R1 and R2 contain at least one sulfur atom.

[0055] In some embodiments, when n is 1, the compound represented by structural formula 1 is:

[0056]

[0057] Where A is selected from C or O, and X is selected from... R1 and R2 are each independently selected from H, R1 and R2 are not both selected from H, and X, R1 and R2 contain at least one sulfur atom.

[0058] In some embodiments, the lithium-ion battery satisfies the following conditions:

[0059]

[0060] When the liquid retention volume M of the non-aqueous electrolyte A The mass percentage W of the compound represented by structural formula 1 in the non-aqueous electrolyte. A When the thickness d of the conductive coating and the compaction density c of the positive electrode material layer further satisfy the above conditions, the combined effects of the conductive coating, the positive electrode material layer, and the compound shown in Formula 1 on the surface interface layer of the positive electrode material layer can be obtained, resulting in a lithium-ion battery with excellent high-temperature cycling and high-temperature storage performance.

[0061] The liquid retention capacity M of the non-aqueous electrolyte A = Electrolyte mass in the lithium-ion battery after formation (g) / Rated capacity of the lithium-ion battery (Ah).

[0062] In some embodiments, the liquid retention capacity M of the non-aqueous electrolyte A It can be 2.8g / Ah, 2.85g / Ah, 2.9g / Ah, 2.95g / Ah, 2.98g / Ah, 3.0g / Ah, 3.05g / Ah, 3.1g / Ah, 3.15g / Ah or 3.2g / Ah.

[0063] In a preferred embodiment, the liquid retention capacity M of the non-aqueous electrolyte is... A For 2.6≤M A ≤3.2g / Ah.

[0064] The liquid retention capacity M of the non-aqueous electrolyte A The relative mass of the positive electrode material layer and the non-aqueous electrolyte in a lithium-ion battery, and the liquid retention capacity M of the non-aqueous electrolyte, are affected. A The mass percentage W of the compound shown in structural formula 1 in a non-aqueous electrolyte A The total amount of the compound shown in Formula 1 added to the secondary battery is determined when the liquid retention M of the non-aqueous electrolyte is... A When within the above range, the positive and negative electrode active materials, separators, etc. in the battery can be fully wetted by the non-aqueous electrolyte, and there are enough compounds as shown in structural formula 1 to form a stable passivation film on the surface of the positive electrode material layer, ensuring the full utilization of the battery capacity and improving the battery capacity, cycle and storage performance.

[0065] In some embodiments, the mass percentage W of the compound represented by structural formula 1 in the non-aqueous electrolyte A The percentages can be 0.1%, 0.12%, 0.15%, 0.3%, 0.5%, 0.8%, 0.9%, 1.0%, 1.2%, 1.4%, 1.7%, 1.9%, 2.1%, 2.2%, 2.4%, 2.7%, 2.9%, 3.1%, 3.3%, 3.5%, 3.9%, 4.1%, 4.3%, 4.6%, 4.9%, or 5.0%.

[0066] In a preferred embodiment, the mass percentage W of the compound represented by structural formula 1 in the non-aqueous electrolyte A It ranges from 0.1% to 2%.

[0067] If the content of the compound shown in Formula 1 in the non-aqueous electrolyte is too low, it cannot effectively form a complete interface film on the surface of the positive electrode material layer, reducing the stability of the positive electrode interface. If the content of the compound shown in Formula 1 in the non-aqueous electrolyte is too high, it will lead to an excessively thick interface film, resulting in excessively high interface impedance, which is not conducive to the performance of battery capacity and rate charge / discharge.

[0068] In some embodiments, the thickness d of the conductive coating is 0.1 μm, 0.12 μm, 0.15 μm, 0.3 μm, 0.5 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.2 μm, 1.4 μm, 1.7 μm, 1.9 μm, 2.1 μm, 2.2 μm, 2.4 μm, 2.7 μm, 2.9 μm, 3.1 μm, 3.3 μm, 3.5 μm, 3. 9μm, 4.1μm, 4.3μm, 4.6μm, 4.9μm, 5.0μm, 6.1μm, 6.3μm, 6.6μm, 6.9μm, 7.0μm, 7.1μm, 7 .3μm, 7.5μm, 7.9μm, 8.1μm, 8.3μm, 8.5μm, 9.0μm, 9.2μm, 9.3μm, 9.5μm, 9.9μm or 10.0μm.

[0069] In a preferred embodiment, the thickness d of the conductive coating is 0.1 to 5 μm.

[0070] In a more preferred embodiment, the thickness d of the conductive coating is 0.1 to 2 μm.

[0071] The thickness of the conductive coating is related to the impedance between the positive current collector and the positive electrode material layer. When the thickness of the conductive coating is within the above range, it can effectively reduce the impedance between the positive current collector and the positive electrode material layer, conduct electrons during the formation process, and help ensure the uniformity of the interface film thickness at different positions on the surface of the positive electrode material layer, thereby improving its stability. If the conductive coating is too thin, the electron conduction effect during the formation process is not good, and the uniformity and integrity of the compound shown in Structural Formula 1 participating in the interface film formation on the surface of the positive electrode particles cannot be achieved, resulting in insufficient high-temperature performance. If the conductive coating is too thick, on the one hand, it increases the electron transport path of the conductive carbon layer, and on the other hand, it increases the thickness of the compound shown in Structural Formula 1 participating in the interface film formation on the surface of the positive electrode particles, causing an increase in impedance, which can easily lead to high-temperature performance degradation.

[0072] In some embodiments, the compaction density c of the positive electrode material layer can be 3.3 g / cm³. 3 3.4g / cm 3 3.5g / cm 3 3.6g / cm 3 3.7g / cm 3 Or 3.8g / cm 3 .

[0073] In a preferred embodiment, the compaction density c of the positive electrode material layer is 3.4–3.6 g / cm³. 3 .

[0074] The positive electrode material layer has a porous structure. The charging and discharging process of the battery actually involves the liquid-phase conduction of lithium ions within the positive electrode material layer. Therefore, the abundance of pores in the positive electrode material layer directly affects the electrochemical performance of the battery. Under the same conditions, the lower the compaction density of the positive electrode material layer, the more developed its pore structure, which is more conducive to the liquid-phase conduction of lithium ions, especially under the harsh conditions of repeated expansion during multiple charge-discharge cycles. However, excessively low compaction density can lead to the positive electrode sheet shedding and powdering, resulting in poor electronic conductivity during charging and lithium plating, affecting the electrochemical performance of the battery and reducing its energy density. Simultaneously, the positive electrode compaction density affects the wetting effect of the non-aqueous electrolyte on the negative electrode and the volume expansion rate of the positive electrode, directly impacting the formation of the interfacial film and the charge-discharge stability. When the compaction density of the positive electrode material layer is within the aforementioned range, the lithium-ion battery exhibits better performance.

[0075] In some embodiments, the conductive coating is a conductive carbon layer comprising a carbon material;

[0076] The carbon material includes at least one of carbon nanotubes, carbon fibers, and conductive carbon black.

[0077] In some embodiments, the conductive coating further includes an adhesive for fixing the carbon material to the surface of the positive electrode current collector.

[0078] In some embodiments, the adhesive comprises at least one of polyvinylidene fluoride (PVDF), copolymers of PVDF, polytetrafluoroethylene (PTFE), copolymers of PVDF-hexafluoropropylene, copolymers of tetrafluoroethylene-hexafluoropropylene, copolymers of tetrafluoroethylene-perfluoroalkyl vinyl ethers, copolymers of ethylene-tetrafluoroethylene, copolymers of PVDF-tetrafluoroethylene, copolymers of PVDF-trifluoroethylene, copolymers of PVDF-trichloroethylene, copolymers of PVDF-fluorinated vinylides, copolymers of PVDF-hexafluoropropylene-tetrafluoroethylene, thermoplastic polyimide, polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, etc.; acrylic resins; sodium hydroxymethyl cellulose; nitrile rubber, polybutadiene rubber, ethylene-propylene rubber, styrene-butadiene-styrene block copolymers or their hydrides, ethylene-propylene-diene terpolymers, polyvinyl acetate, syndiotactic-1,2-polybutadiene, and ethylene-vinyl acetate.

[0079] In some embodiments, the conductive coating comprises 70% to 90% by weight of carbon material and 10% to 30% by weight of binder.

[0080] In some embodiments, the compound represented by structural formula 1 is selected from at least one of the following compounds:

[0081]

[0082]

[0083]

[0084] It should be noted that the above are only preferred compounds of the present invention and do not represent a limitation on the present invention.

[0085] Those skilled in the art, knowing the structural formula of the compound shown in structural formula 1, can understand the preparation method of the above-mentioned compound based on common knowledge in the field of chemical synthesis. For example, compound 7 can be prepared by the following method:

[0086] Sorbitol, dimethyl carbonate, methanol, potassium hydroxide catalyst, and organic solvents such as DMF were placed in a reaction vessel and reacted under heating conditions for several hours. Then, a certain amount of oxalic acid was added to adjust the pH to neutral. After filtration and recrystallization, intermediate product 1 was obtained. Then, intermediate product 1, carbonate, thionyl chloride, etc. were subjected to esterification reaction under high temperature conditions to obtain intermediate product 2. Then, intermediate product 2 was oxidized with an oxidizing agent such as sodium periodate to obtain compound 7.

[0087] In some embodiments, the lithium-ion battery is a pouch battery or a hard-shell battery.

[0088] In some embodiments, the positive electrode material layer includes a positive electrode active material, wherein the positive electrode active material includes LiFe. 1-x’ M' x’ PO4, LiMn 2-y’ M y’ O4 and LiNi x Co y Mn z M 1-x-y-z O2, at least one of sulfides, selenides, and halides, wherein M' is selected from at least one of Mn, Mg, Co, Ni, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V, or Ti, and M is selected from at least one of Fe, Co, Ni, Mn, Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V, or Ti, and 0≤x'<1, 0≤y'≤1, 0≤y≤1, 0≤x≤1, 0≤z≤1, and x+y+z≤1.

[0089] In some embodiments, the positive current collector is selected from a metallic material that can conduct electrons. Preferably, the positive current collector includes at least one of Al, Ni, tin, copper, and stainless steel. In a more preferred embodiment, the positive current collector is selected from aluminum foil.

[0090] In some embodiments, the positive electrode material layer further includes a positive electrode binder and a positive electrode conductive agent.

[0091] The positive electrode binder includes at least one of the following: polyvinylidene fluoride (PVDF), copolymers of PVDF, polytetrafluoroethylene (PTFE), copolymers of PVDF-hexafluoropropylene, copolymers of tetrafluoroethylene-hexafluoropropylene, copolymers of tetrafluoroethylene-perfluoroalkyl vinyl ethers, copolymers of ethylene-tetrafluoroethylene, copolymers of PVDF-tetrafluoroethylene, copolymers of PVDF-trifluoroethylene, copolymers of PVDF-trichloroethylene, copolymers of PVDF-fluorinated vinylidene, copolymers of PVDF-hexafluoropropylene-tetrafluoroethylene, thermoplastic polyimide, polyethylene, and polypropylene; acrylic resins; sodium carboxymethyl cellulose; and styrene-butadiene rubber.

[0092] The positive electrode conductive agent includes at least one of conductive carbon black, conductive carbon spheres, conductive graphite, conductive carbon fiber, carbon nanotubes, graphene, or reduced graphene oxide.

[0093] In some embodiments, the negative electrode material layer includes a negative electrode active material, which includes at least one of carbon-based, silicon-based, tin-based, and lithium-based negative electrodes. The carbon-based negative electrode may include graphite, hard carbon, soft carbon, graphene, mesophase carbon microspheres, etc.; the silicon-based negative electrode may include silicon materials, silicon oxides, silicon-carbon composite materials, and silicon alloy materials, etc.; the tin-based negative electrode may include tin, tin-carbon, tin-oxygen, and tin metal compounds; and the lithium-based negative electrode may include metallic lithium or lithium alloys. Specifically, the lithium alloy may be at least one of lithium-silicon alloys, lithium-sodium alloys, lithium-potassium alloys, lithium-aluminum alloys, lithium-tin alloys, and lithium-indium alloys.

[0094] In some embodiments, the negative electrode material layer further includes a negative electrode binder and a negative electrode conductive agent, and the negative electrode active material, the negative electrode binder and the negative electrode conductive agent are blended to obtain the negative electrode material layer.

[0095] The selectable ranges of the negative electrode adhesive and negative electrode conductive agent are the same as those of the positive electrode adhesive and positive electrode conductive agent, and will not be repeated here.

[0096] In some embodiments, the negative electrode further includes a negative electrode current collector, and the negative electrode material layer is formed on the surface of the negative electrode current collector.

[0097] The negative electrode current collector is selected from a metallic material that can conduct electrons. Preferably, the negative electrode current collector includes at least one of Al, Ni, tin, copper, and stainless steel. In a more preferred embodiment, the negative electrode current collector is selected from copper foil.

[0098] In some embodiments, the non-aqueous organic solvent includes at least one of ether solvents, nitrile solvents, carbonate solvents, and carboxylic acid ester solvents.

[0099] In some embodiments, the ether solvent includes cyclic ethers or chain ethers, preferably chain ethers with 3 to 10 carbon atoms and cyclic ethers with 3 to 6 carbon atoms. The cyclic ethers may specifically include, but are not limited to, at least one of 1,3-dioxolane (DOL), 1,4-dioxane (DX), crown ethers, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-CH3-THF), and 2-trifluoromethyltetrahydrofuran (2-CF3-THF). The chain ethers may specifically include, but are not limited to, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether. Because chain ethers have high solvation ability with lithium ions and can improve ion dissociation, dimethoxymethane, diethoxymethane, and ethoxymethoxymethane, which have low viscosity and can impart high ionic conductivity, are particularly preferred. Ether compounds can be used alone or in any combination and ratio of two or more. There are no particular restrictions on the amount of ether compounds added; it is arbitrary as long as it does not significantly impair the performance of the high-pressure lithium-ion battery of this invention. Typically, the volume ratio is 1% or more, preferably 2% or more, and more preferably 3% or more when the non-aqueous solvent volume ratio is 100%. Furthermore, the volume ratio is typically 30% or less, preferably 25% or less, and more preferably 20% or less. When using two or more ether compounds in combination, the total amount of ether compounds should meet the above-mentioned range. When the amount of ether compounds added is within the above-mentioned preferred range, it is easy to ensure the improved ionic conductivity resulting from the increased lithium-ion dissociation degree and reduced viscosity of the chain ethers. Additionally, when the negative electrode active material is a carbon-based material, the phenomenon of co-intercalation between the chain ethers and lithium ions can be suppressed, thus enabling the input / output characteristics and charge / discharge rate characteristics to reach an appropriate range.

[0100] In some embodiments, the nitrile solvent may be, but is not limited to, at least one of acetonitrile, glutaronitrile, and malononitrile.

[0101] In some embodiments, the carbonate solvent includes cyclic carbonates or chain carbonates. Cyclic carbonates may specifically include, but are not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (GBL), and butylene carbonate (BC); chain carbonates may specifically include, but are not limited to, at least one of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and dipropyl carbonate (DPC). The content of cyclic carbonates is not particularly limited and is arbitrary within a range that does not significantly impair the performance of the lithium-ion battery of the present invention. However, when using only one type, its lower limit relative to the total volume of the non-aqueous electrolyte solvent is typically 3% or more, preferably 5% or more. By setting this range, a decrease in conductivity due to a decrease in the dielectric constant of the non-aqueous electrolyte can be avoided, making it easier to achieve good high-current discharge characteristics, stability relative to the negative electrode, and cycle characteristics of the non-aqueous electrolyte battery. Furthermore, the upper limit is typically 90% or less, preferably 85% or less, and more preferably 80% or less. By setting this range, the oxidation / reduction resistance of the non-aqueous electrolyte can be improved, thereby contributing to enhanced stability during high-temperature storage. The content of the chain carbonate is not particularly limited, but relative to the total amount of solvent in the non-aqueous electrolyte, it is typically 15% or more by volume, preferably 20% or more, and more preferably 25% or more. Furthermore, it is typically 90% or less by volume, preferably 85% or less, and more preferably 80% or less. By keeping the chain carbonate content within the above range, it is easier to achieve an appropriate viscosity for the non-aqueous electrolyte, suppressing the decrease in ionic conductivity, and thus contributing to achieving a favorable range of output characteristics for the non-aqueous electrolyte battery. When using two or more chain carbonates in combination, it is sufficient to ensure that the total amount of chain carbonate meets the above range.

[0102] In some embodiments, fluorine-containing chain carbonates (hereinafter referred to as "fluorinated chain carbonates") are also preferably used. There is no particular limitation on the number of fluorine atoms in a fluorinated chain carbonate as long as it is 1 or more, but it is generally 6 or less, preferably 4 or less. When a fluorinated chain carbonate has multiple fluorine atoms, these fluorine atoms can be bonded to the same carbon atom or to different carbon atoms. Examples of fluorinated chain carbonates include dimethyl fluorinated carbonate derivatives, methyl ethyl fluorinated carbonate derivatives, and diethyl fluorinated carbonate derivatives.

[0103] Carboxylic acid ester solvents include cyclic carboxylic acid esters and / or chain carbonates. Examples of cyclic carboxylic acid esters include at least one of γ-butyrolactone, γ-valerolactone, and δ-valerolactone. Examples of chain carbonates include at least one of methyl acetate (MA), ethyl acetate (EA), propyl acetate (EP), butyl acetate, propyl propionate (PP), and butyl propionate.

[0104] In some embodiments, the sulfone solvent includes cyclic sulfones and chain sulfones. Preferably, in the case of cyclic sulfones, it is typically a compound with 3 to 6 carbon atoms, more preferably 3 to 5 carbon atoms; in the case of chain sulfones, it is typically a compound with 2 to 6 carbon atoms, more preferably 2 to 5 carbon atoms. There are no particular limitations on the amount of sulfone solvent added, and it is arbitrary within a range that does not significantly impair the performance of the lithium-ion battery of the present invention. Relative to the total amount of solvent in the non-aqueous electrolyte, it is typically 0.3% or more by volume, preferably 0.5% or more by volume, more preferably 1% or more by volume. Furthermore, it is typically 40% or less by volume, preferably 35% or less by volume, more preferably 30% or less by volume. When using two or more sulfone solvents in combination, the total amount of sulfone solvent should satisfy the above range. When the amount of sulfone solvent added is within the above range, a non-aqueous electrolyte with excellent high-temperature storage stability is tended to be obtained.

[0105] In a preferred embodiment, the non-aqueous organic solvent is a mixture of cyclic carbonates and chain carbonates.

[0106] In some embodiments, the lithium salt is selected from LiPF6, LiBOB, LiDFOB, LiPO2F2, LiBF4, LiSbF6, LiAsF6, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiN(SO2F)2, LiClO4, LiAlCl4, LiCF3SO3, Li2B 10 Cl 10 At least one of LiSO2F, LiTOP (lithium trioxarate phosphate), LiDODFP (lithium difluorodioxarate phosphate), LiOTFP (lithium tetrafluorooxarate phosphate), and lower aliphatic carboxylic acid lithium salts.

[0107] In some embodiments, the concentration of the lithium salt in the non-aqueous electrolyte is 0.1 mol / L to 8 mol / L. In a preferred embodiment, the concentration of the lithium salt in the non-aqueous electrolyte is 0.5 mol / L to 2.5 mol / L. Specifically, the concentration of the lithium salt in the non-aqueous electrolyte can be 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, or 2.5 mol / L.

[0108] In some embodiments, the additive further includes at least one selected from cyclic sulfate compounds, sulfonyl lactone compounds, cyclic carbonate compounds, phosphate compounds, borate compounds, and nitrile compounds;

[0109] Preferably, the content of the additive is 0.01% to 30% based on the total mass of the non-aqueous electrolyte (100%).

[0110] In some embodiments, the cyclic sulfate compound is selected from vinyl sulfate, propylene sulfate, methyl vinyl sulfate, etc. At least one of them;

[0111] The sulfonyl lactone compound is selected from at least one of 1,3-propanesulfonyl lactone, 1,4-butanesulfonyl lactone, and 1,3-propenesulfonyl lactone.

[0112] The cyclic carbonate compounds are selected from vinylene carbonate, ethylene ethylene carbonate, methylene carbonate, fluoroethylene carbonate, trifluoromethyl ethylene carbonate, difluoroethylene carbonate, or other compounds with the following structure.

[0113] At least one of the compounds shown in Formula 2:

[0114]

[0115] In structural formula 2, R 21 R 22 R 23 R 24 R 25 R 26 Each is independently selected from one of the following: hydrogen atom, halogen atom, or C1-C5 group;

[0116] The phosphate ester compound is selected from at least one of tris(trimethylsilane) phosphate, tris(trimethylsilane) phosphite, or the compound shown in structural formula 3:

[0117]

[0118] In structural formula 3, R 31 R 32 R 33 Each is independently selected from C1-C5 saturated hydrocarbon groups, unsaturated hydrocarbon groups, halohydrocarbon groups, and -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and R 31 R 32 R 33 At least one of them is an unsaturated hydrocarbon group;

[0119] In a preferred embodiment, the phosphate ester compound represented by structural formula 3 may be at least one of the following: triargyl phosphate, diallyl methyl phosphate, diallyl ethyl phosphate, diallyl propyl phosphate, diallyl trifluoromethyl phosphate, diallyl-2,2,2-trifluoroethyl phosphate, diallyl-3,3,3-trifluoropropyl phosphate, diallyl hexafluoroisopropyl phosphate, triallyl phosphate, diallyl methyl phosphate, diallyl ethyl phosphate, diallyl propyl phosphate, diallyl trifluoromethyl phosphate, diallyl-2,2,2-trifluoroethyl phosphate, diallyl-3,3,3-trifluoropropyl phosphate, and diallyl hexafluoroisopropyl phosphate.

[0120] The borate ester compound is selected from at least one of tris(trimethylsilane)borate ester and tris(triethylsilane)borate ester;

[0121] The nitrile compound is selected from at least one of butadionitrile, glutaronitrile, ethylene glycol bis(propionitrile) ether, hexanetrionitrile, adiponitrile, heptanonitrile, octadionitrile, nonadionitrile, and sebaconitrile.

[0122] In other embodiments, the additive may also include other additives that can improve battery performance: for example, additives that improve battery safety performance, such as flame retardant additives like fluorophosphates and cyclophosphonitriles, or overcharge prevention additives like tert-amylbenzene and tert-butylbenzene.

[0123] It should be noted that, unless otherwise specified, the content of any optional substance in the additive in the non-aqueous electrolyte is generally less than 10%, preferably 0.1-5%, and more preferably 0.1% to 2%. Specifically, the content of any optional substance in the additive can be 0.05%, 0.08%, 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 7.8%, 8%, 8.5%, 9%, 9.5%, or 10%.

[0124] In some embodiments, when the additive is selected from fluoroethylene carbonate, the content of fluoroethylene carbonate is 0.05% to 30% based on 100% of the total mass of the non-aqueous electrolyte.

[0125] In some embodiments, the lithium-ion battery further includes a separator located between the positive electrode and the negative electrode.

[0126] The diaphragm can be a conventional diaphragm, such as a ceramic diaphragm, a polymer diaphragm, a non-woven fabric, or an inorganic-organic composite diaphragm. The polymer diaphragm is selected from one or more of polyolefins, polyamides, polysulfones, polyphosphazenes, polyethersulfones, polyetheretherketones, polyetheramides, and polyacrylonitriles, including but not limited to single-layer PP (polypropylene), single-layer PE (polyethylene), double-layer PP / PE, double-layer PP / PP, and triple-layer PP / PE / PP diaphragms.

[0127] In a preferred embodiment, the diaphragm includes a substrate diaphragm and a surface coating, wherein the surface coating is inorganic particles or an organic gel or a mixture thereof and is coated on at least one side of the substrate diaphragm.

[0128] The present invention will be further illustrated by the following examples.

[0129] The compounds involved in the following examples and comparative examples are shown in the table below:

[0130] Table 1

[0131]

[0132]

[0133] Table 2. Parameter Design of Examples and Comparative Examples

[0134]

[0135]

[0136] Example 1

[0137] This embodiment uses the preparation of a lithium-ion battery as an example to illustrate the present invention, including the following operation steps:

[0138] The preparation steps of the positive electrode are as follows: a conductive carbon black (Super-P) solution with a solid content of 63% is uniformly coated onto the surface of an aluminum foil to obtain a positive electrode current collector containing a conductive coating. The central region of the positive electrode current collector is then cut to form a cross-section with a width of 0.5 cm. Quantitative analysis of this cross-section is performed using SEM. The thickness of the aluminum foil substrate is measured as d0, and the total thickness of the entire positive electrode current collector (including the conductive coating and the aluminum foil substrate) is measured as d1. The calculation formula is as follows:

[0139] The thickness of the conductive carbon layer is d = d1 - d0;

[0140] The thickness d of the conductive carbon layer was measured and calculated 5 times, and the average value was recorded in Table 2.

[0141] The ternary cathode active material LiNi was mixed at a mass ratio of 93:4:3. 0.5 Co 0.2Mn 0.3 O2, conductive carbon black (Super-P) and binder polyvinylidene fluoride (PVDF) are dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a positive electrode slurry. The positive electrode slurry is uniformly coated on both sides of the positive electrode current collector, and after drying, rolling and vacuum drying, aluminum leads are welded on using an ultrasonic welding machine to obtain the positive electrode. The compaction density of the positive electrode material is controlled by the areal density and rolling thickness of the positive electrode material, as shown in Table 2.

[0142] The negative electrode preparation steps are as follows: artificial graphite, conductive carbon black, styrene-butadiene rubber (SBR) binder and carboxymethyl cellulose (CMC) are mixed in a mass ratio of 94:1:2.5:2.5 and dispersed in deionized water to obtain a negative electrode slurry. The negative electrode slurry is coated on both sides of a copper foil, dried, rolled and vacuum dried, and nickel leads are welded on using an ultrasonic welding machine to obtain the negative electrode.

[0143] The electrolyte preparation steps are as follows: ethylene carbonate, diethyl carbonate and methyl ethyl carbonate are mixed in a volume ratio of EC:DEC:EMC = 1:1:1, and then lithium hexafluorophosphate with a concentration of 1.0 mol / L is added, along with compound 7 in the mass parts shown in Table 2.

[0144] The membrane preparation steps are as follows: a three-layer membrane of polypropylene, polyethylene and polypropylene with a thickness of 20μm is used;

[0145] The battery assembly steps are as follows: a three-layer separator with a thickness of 20μm is placed between the positive and negative electrodes. Then, the sandwich structure composed of the positive electrode plate, negative electrode plate and separator is wound up. The wound body is flattened and placed into a square aluminum metal shell. The leads of the positive and negative electrodes are welded to the corresponding positions on the cover plate. The cover plate and the metal shell are welded together by a laser welding machine to obtain the cell to be injected with electrolyte. The electrolyte prepared above is injected into the cell through the injection hole. The liquid retention of the non-aqueous electrolyte is shown in Table 2.

[0146] Then proceed with the following routine formation steps: charge at a constant current of 0.05C for 180 minutes, charge at a constant current of 0.2C to 3.95V, vacuum seal twice, then charge at a constant current of 0.2C to 4.4V cutoff voltage, let stand at room temperature for 24 hours, and then discharge at a constant current of 0.2C to 3.0V.

[0147] Examples 2-27

[0148] Examples 2-27 illustrate the lithium-ion battery and its preparation method disclosed in this invention, including most of the operational steps in Example 1, with the following differences:

[0149] The thickness of the conductive coating, the compaction density of the positive electrode material layer, the mass percentage of additives in the non-aqueous electrolyte, and the liquid retention of the non-aqueous electrolyte used in Examples 2 to 27 are shown in Table 2.

[0150] Comparative Examples 1-19

[0151] Comparative Examples 1-19 are used to illustrate the lithium-ion battery and its preparation method disclosed in this invention, including most of the operation steps in Example 1, with the following differences:

[0152] The thickness of the conductive coating, the compaction density of the positive electrode material layer, the mass percentage of the compound shown in structural formula 1 in the non-aqueous electrolyte, and the liquid retention of the non-aqueous electrolyte used in Comparative Examples 1 to 19 are shown in Table 2.

[0153] Performance testing

[0154] The lithium-ion batteries prepared above were subjected to the following performance tests:

[0155] 1) High-temperature storage performance: At 25℃, the conventionally formed battery is charged to 4.4V using a 0.5C constant current and constant voltage method, with a cutoff current of 0.05C. Then, it is discharged to 3.0V using a 1C constant current method, and then charged again to 4.4V using a 0.5C constant current and constant voltage method, with a cutoff current of 0.05C. The capacity of this first discharge is taken as the capacity C0 before storage. Then, the battery is placed at 70℃ for 30 days, followed by a 1C constant current discharge to 3V. This capacity is taken as the capacity C1 after storage. The calculation formula is as follows:

[0156] Storage capacity retention rate R = C1 / C0 × 100%;

[0157] 2) High-temperature cycling performance: At 25℃, the conventionally formed battery was charged to 4.4V using a 0.5C constant current and constant voltage method, then discharged to 3.0V using a 0.5C constant current method, for two pre-cycles. Then, it was placed at 45℃ for 3 hours, charged to 4.4V using a 1C constant current and constant voltage method, and discharged using a 1C constant current method. The first discharge capacity C0 was recorded. Thereafter, it was cycled at 1C / 1C within the 3-4.4V voltage range. The discharge capacity after 400 cycles was recorded as C1. The calculation formula is as follows:

[0158] Cyclic capacity retention rate R = C1 / C0 × 100%;

[0159] (1) The test results obtained from Examples 1-18 and Comparative Examples 1-19 are filled in Table 3.

[0160] Table 3

[0161]

[0162]

[0163] The test results from Examples 1-18 and Comparative Examples 1-19 show that there is a clear correlation between the compound shown in Structural Formula 1, the liquid retention capacity of the non-aqueous electrolyte, the conductive coating on the positive electrode current collector, and the compaction density of the positive electrode material layer in improving the high-temperature cycle performance and high-temperature storage performance of lithium-ion batteries. A The mass percentage W of the compound shown in structural formula 1 in the non-aqueous electrolyte A The thickness d of the conductive coating and the compaction density c of the positive electrode material layer satisfy the following relationship: And 2.4≤M A ≤3.6, 0.1≤W A When ≤5, 0.1≤d≤10, and 3.3≤c≤3.8, the resulting lithium-ion battery exhibits high cycle capacity retention, high-temperature storage capacity retention, and low impedance growth. This is presumably because the conductive coating on the surface of the positive electrode current collector improves the static conductivity of the current collector. By controlling the thickness of the conductive coating, the microcurrent of the positive electrode material layer can be balanced, allowing the compound shown in Structural Formula 1 to participate more fully in forming a complete interface film on the surface of the positive electrode material layer. At the same time, the compaction density of the positive electrode material layer, the liquid retention of the non-aqueous electrolyte, and the mass percentage of the compound shown in Structural Formula 1 in the non-aqueous electrolyte directly affect the sufficiency of the surface contact between the compound shown in Structural Formula 1 and the positive electrode material layer, as well as the consumption decomposition rate and diffusion efficiency of the compound shown in Structural Formula 1 on the surface of the positive electrode material layer during the formation stage. By correlating the above parameters and optimizing the relationship among the four, the compound shown in Structural Formula 1 can form a film sufficiently, and the resulting interface film has high thermal stability and low impedance, thereby effectively improving the high-temperature cycle and storage performance of the lithium-ion battery.

[0164] Comparing the test results of Examples 1-18, it can be seen that when the liquid retention M of the non-aqueous electrolyte... A The mass percentage W of the compound shown in structural formula 1 in the non-aqueous electrolyte A The thickness d of the conductive coating and the compaction density c of the positive electrode material layer further satisfy... And 2.6≤M A ≤3.2, 0.1≤W A When the values ​​are ≤2, 0.1≤d≤5, and 3.4≤c≤3.6, lithium-ion batteries exhibit the best overall battery performance.

[0165] As can be seen from the test results of Comparative Examples 1 to 6, in the battery system provided by the present invention, the addition of the compound shown in Structural Formula 1 and the setting of the conductive coating are both key influencing factors. When the compound shown in Structural Formula 1 is not added or the conductive coating is not set, the high-temperature cycle performance and high-temperature storage performance of the lithium-ion battery will be significantly reduced.

[0166] The test results of Comparative Examples 12-19 show that even the liquid retention capacity M of the non-aqueous electrolyte... A The mass percentage W of the compound shown in structural formula 1 in the non-aqueous electrolyte A The thickness d of the conductive coating and the compaction density c of the positive electrode material layer satisfy the condition. The limitation, but M A Value, W A When the initial capacity, d-value, or c-value does not meet the specified range, the lithium-ion battery still does not exhibit good initial capacity utilization, high-temperature cycle performance, and high-temperature storage performance, indicating that M... A Value, W A The values ​​of M, d, and c have a strong correlation with improving the energy density and high-temperature performance of lithium-ion batteries. Similarly, as shown in Comparative Examples 7-11, when M... A Value, W A When the value, d value, or c value meets its range limit, but When the above preset conditions are not met, the electrochemical performance of the battery will deteriorate, indicating that the conditions... It can correlate various influencing factors and comprehensively analyze their impact on lithium-ion battery performance to achieve a better synergistic effect.

[0167] (2) The test results obtained in Examples 6 and 19-23 are filled in Table 4.

[0168] Table 4

[0169]

[0170] The test results from Examples 6 and 19-23 show that, for different compounds represented by structural formula 1, the liquid retention capacity M of the non-aqueous electrolyte is... A The mass percentage W of the compound shown in structural formula 1 in the non-aqueous electrolyte A The thickness d of the conductive coating and the compaction density c of the positive electrode material layer meet the preset conditions. At the same time, they play similar roles, all of which have a certain improvement effect on reducing the high-temperature cycle impedance of lithium-ion batteries, improving the initial capacity of the battery, and enhancing the high-temperature cycle and storage performance. This shows that the relationship provided by the present invention is applicable to different compounds shown in structural formula 1.

[0171] (3) The test results obtained in Examples 6 and 24-27 are filled in Table 5.

[0172] Table 5

[0173]

[0174] As can be seen from the test results of Examples 6 and 24-27, in batteries containing the positive electrode provided by the present invention, the addition of the above-mentioned additives VC (ethylene carbonate), FEC (fluoroethylene carbonate), DTD (ethylene sulfate), or triargyl phosphate to the non-aqueous electrolyte can further improve the high-temperature cycle capacity retention rate and high-temperature storage capacity retention rate of the battery. It is speculated that this is because the compound shown in structural formula 1 on the positive electrode material layer, together with the above-mentioned additives, participates in the formation of the interface film on the electrode surface, resulting in an interface film with excellent thermal stability, thereby effectively reducing the reaction of the electrolyte on the electrode surface under high-temperature conditions and improving the electrochemical performance of the battery.

[0175] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A lithium-ion battery, characterized in that, The electrolyte includes a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode includes a positive electrode current collector with a conductive coating on its surface and a positive electrode material layer disposed on the positive electrode current collector. The non-aqueous electrolyte includes a non-aqueous organic solvent, a lithium salt, and an additive. The additive includes a compound represented by structural formula 1. Where n is 0 or 1, A is selected from C or O, and X is selected from... R1 and R2 are each independently selected from H, R1 and R2 are not both selected from H, and X, R1 and R2 contain at least one sulfur atom; The lithium-ion battery meets the following conditions: And 2.4≤M A ≤3.6, 0.1≤W A ≤5, 0.1≤d≤10, 3.3≤c≤3.8; wherein M A is the liquid retention of the nonaqueous electrolyte, in g / Ah; W A is the mass percentage content of the compound represented by structural formula 1 in the non-aqueous electrolyte, in %; d represents the thickness of the conductive coating, in μm; c is the compacted density of the positive electrode material layer, in g / cm 3 .

2. The lithium-ion battery according to claim 1, characterized in that, The lithium-ion battery meets the following conditions:

3. The lithium-ion battery according to claim 1, characterized in that, The nonaqueous electrolyte solution has a liquid retention amount M A is 2.6 to 3.2 g / Ah.

4. The lithium-ion battery according to claim 1, characterized in that, The mass percentage content W of the compound represented by structural formula 1 in the nonaqueous electrolyte is 0.1% to 2%. A 0.1% to 2%.

5. The lithium-ion battery according to claim 1, characterized in that, The thickness d of the conductive coating is 0.1 to 5 μm.

6. The lithium-ion battery according to claim 1, characterized in that, The compacted density c of the positive electrode material layer is 3.4 to 3.6 g / cm 3 .

7. The lithium-ion battery according to claim 1, characterized in that, The conductive coating is a conductive carbon layer comprising carbon material; The carbon material includes at least one of carbon nanotubes, carbon fibers, and conductive carbon black.

8. The lithium-ion battery according to claim 1, characterized in that, The compound represented by structural formula 1 is selected from at least one of the following compounds: 。 9. The lithium-ion battery according to claim 1, characterized in that, The additives also include at least one of the following: cyclic sulfate compounds, sulfonyl lactone compounds, cyclic carbonate compounds, phosphate compounds, borate compounds, and nitrile compounds; Based on the total mass of the non-aqueous electrolyte as 100%, the content of the additive is 0.01% to 30%.

10. The lithium-ion battery according to claim 9, characterized in that, The cyclic sulfate compounds are selected from vinyl sulfate, propylene sulfate, methyl vinyl sulfate, etc. At least one of them; The sulfonyl lactone compound is selected from at least one of 1,3-propanesulfonyl lactone, 1,4-butanesulfonyl lactone, and 1,3-propenesulfonyl lactone. The cyclic carbonate compound is selected from at least one of vinylene carbonate, ethylene ethylene carbonate, methylene carbonate, fluoroethylene carbonate, trifluoromethyl ethylene carbonate, difluoroethylene carbonate, or the compound shown in structural formula 2. In the structural formula 2, R 21 , R 22 , R 23 , R 24 , R 25 , R 26 each is independently selected from one of a hydrogen atom, a halogen atom, a C1-C5 group; The phosphate ester compound is selected from at least one of tris(trimethylsilane) phosphate, tris(trimethylsilane) phosphite, or the compound shown in structural formula 3: In structural formula 3, R 31 R 32 R 33 Each is independently selected from C1-C5 saturated hydrocarbon groups, unsaturated hydrocarbon groups, halohydrocarbon groups, and -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and R 31 R 32 R 33 At least one of them is an unsaturated hydrocarbon group; The borate ester compound is selected from at least one of tris(trimethylsilane)borate ester and tris(triethylsilane)borate ester; The nitrile compound is selected from at least one of butadionitrile, glutaronitrile, ethylene glycol bis(propionitrile) ether, hexanetrionitrile, adiponitrile, heptanonitrile, octadionitrile, nonadionitrile, and sebaconitrile.

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