Non-aqueous electrolyte and lithium ion battery containing the same

Abstract

The application provides a non-aqueous electrolyte and a lithium ion battery. The non-aqueous electrolyte comprises a lithium salt, a non-aqueous organic solvent and an additive. The additive comprises a compound A with a structural formula as shown in Formula I and a compound B with a structural formula as shown in Formula II. Wherein, R1, R2, R3, R4 and R5 are each independently selected from substituted or unsubstituted C1-C5 hydrocarbyl and C1-C5 alkyl ketone, R6 and R7 are each independently selected from hydrogen, cyano and cyano-substituted C1-C5 hydrocarbyl, at least one of R1, R2, R3, R4, R5, R6 and R7 contains cyano, R8, R9 and R 10 are each independently selected from substituted or unsubstituted C1-C5 hydrocarbyl, 11 are each independently selected from substituted or unsubstituted C1-C5 hydrocarbyl and cyano. The introduction of the compound A and the compound B in the non-aqueous electrolyte can accelerate the ion transmission rate, improve the fast-charging cycle performance of the lithium ion battery and reduce the internal resistance.

Description

Technical Field

[0001] This invention relates to the field of energy storage device technology, particularly to secondary batteries, and even more particularly to a non-aqueous electrolyte and a lithium-ion battery containing the non-aqueous electrolyte. Background Technology

[0002] Ternary lithium-ion batteries, with their high energy density, have become the core power source for electric vehicles and energy storage systems. Increasing the charging cut-off voltage is a direct and effective technical path to continuously improve energy density, but this also leads to increasingly harsh battery operating environments. Traditional carbonate-based electrolytes are prone to oxidative decomposition under high voltage, causing not only continuous electrolyte consumption and a surge in interfacial impedance, but also severe gas generation problems, leading to battery swelling. Simultaneously, high voltage exacerbates the interfacial instability of high-nickel ternary cathode materials, triggering the dissolution of transition metal ions and damaging the integrity of the solid electrolyte interfacial film at the negative electrode. Ultimately, this results in rapid capacity decay, shortened cycle life, and significant safety hazards, severely restricting the commercial application of high-voltage ternary batteries.

[0003] Currently, developing suitable high-voltage electrolyte systems is a key solution to address the aforementioned problems. Mainstream strategies focus on introducing functional additives, such as sulfur- or phosphorus-containing compounds, to construct a stable interfacial protective film on the cathode surface. However, existing additive systems often have limited functionality, making it difficult to achieve synergistic optimization across multiple dimensions, including efficient film formation, gas suppression, and removal of harmful substances. While some additives improve interfacial stability, they may also introduce new problems such as increased impedance, decreased low-temperature performance, or poor compatibility with other components. Therefore, developing a novel electrolyte additive that can comprehensively and synergistically stabilize the electrode / electrolyte interface, especially exhibiting excellent film formation capabilities and significant gas suppression effects at high voltages, is of great significance for overcoming the performance bottlenecks of high-voltage ternary lithium-ion batteries. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a non-aqueous electrolyte and a lithium-ion battery. This non-aqueous electrolyte incorporates compounds A and B as electrolyte additives, which can accelerate ion transport rate, improve the fast-charge cycle performance of the lithium-ion battery, and simultaneously reduce internal resistance.

[0005] To achieve the above objectives, a first aspect of the present invention provides a non-aqueous electrolyte comprising a lithium salt, a non-aqueous organic solvent, and an additive, wherein the additive comprises compound A with the structural formula shown in Formula 1 and compound B with the structural formula shown in Formula 2, wherein R1, R2, R3, R4, and R5 are each independently selected from substituted or unsubstituted C1-C5 hydrocarbon groups and C1-C5 alkyl ketone groups, R6 and R7 are each independently selected from hydrogen, cyano, or cyano-substituted C1-C5 hydrocarbon groups, at least one of R1, R2, R3, R4, R5, R6, and R7 contains a cyano group, and R8, R9, and R... 10 Each is independently selected from substituted or unsubstituted C1-C5 hydrocarbon groups, R 11 Selected from substituted or unsubstituted C1-C5 hydrocarbon groups and cyano groups.

[0006]

[0007] The additives in the non-aqueous electrolyte of the present invention include compound A as shown in Formula 1 and compound B as shown in Formula 2. Compound A is a xylose compound with a cyano group, whose cyano group (-CN) reacts with high-valence transition metal ions (such as Ni) on the surface of the cathode material. 4+ (etc.) undergo strong coordination, directly stabilizing the surface. In addition to the crystal lattice, the decomposition products of xylose compounds can participate in the construction of a stable cathode electrolyte interphase (CEI) film rich in LiF and -CN to suppress electrolyte decomposition and transition metal dissolution. However, xylose compounds have large steric hindrance, and their ability to modify the negative electrode SEI film when used alone is limited, making it difficult to fully suppress side reactions during high-temperature cycling. Compound B, on the other hand, contains a P=N double bond structure, which has multiple functional properties: firstly, the P=N double bond structure has a unique electronic structure and good thermal stability, enabling it to remain stable under high-temperature conditions; secondly, the phosphorimine compound can preferentially reduce at the electrode interface to form a LiF-rich inorganic interfacial film. This inorganic-rich interfacial film has high ionic conductivity and excellent mechanical strength, thus significantly improving the high-temperature cycling performance of the medium-ternary high-voltage system.

[0008] As a technical solution of the present invention, R1, R2, R3, R4, and R5 are each independently selected from unsubstituted C1-C5 alkyl groups, cyano-substituted C1-C5 alkyl groups, and C1-C3 alkyl ketone groups; R6 and R7 are each independently selected from hydrogen and cyano groups; R8, R9, and R 10 Each alkyl group is independently selected from substituted or unsubstituted C1-C5 alkyl groups, R 11 Selected from unsubstituted C1-C5 alkyl, cyano, or alkylsilyl-substituted C1-C5 alkyl groups.

[0009] As a technical solution of the present invention, compound A is selected from at least one of compounds one to three.

[0010]

[0011] As one technical solution of the present invention, compound B is selected from at least one of compounds four to six.

[0012]

[0013] As a technical solution of the present invention, based on the mass of the electrolyte salt, the non-aqueous organic solvent and the additive being 100%, the mass percentage of compound A is 0.05~2.00%, and the mass percentage of compound B is 0.05~2.00%.

[0014] As a technical solution of the present invention, the electrolyte salt is a lithium salt, which is selected from at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(oxalate-borate), lithium difluorophosphate, lithium fluorosulfonate, lithium difluorooxalate-borate, lithium lower aliphatic carboxylic acids, lithium difluorodioxalate phosphate, and lithium bis(fluorosulfonyl)imide.

[0015] As a technical solution of the present invention, the non-aqueous organic solvent is selected from at least one of γ-butyrolactone, γ-valerolactone, δ-valerolactone, methyl acetate, ethyl acetate, ethyl propionate, butyl acetate, propyl propionate, butyl propionate, ethylene carbonate, propylene carbonate, butyl carbonate, methyl pentyl carbonate, vinylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, propylene carbonate, 1,3-dioxolane, 1,4-dioxane, crown ether, tetrahydrofuran, 2-methyltetrahydrofuran, 2-trifluoromethyltetrahydrofuran, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether.

[0016] A second aspect of the present invention provides a lithium-ion battery, comprising a positive electrode material, a negative electrode material and an electrolyte, wherein the electrolyte is selected from the aforementioned non-aqueous electrolytes.

[0017] As a technical solution of the present invention, the positive electrode material is selected from at least one of lithium nickel cobalt manganese oxide materials and lithium nickel cobalt aluminum oxide materials.

[0018] As one technical solution of the present invention, the negative electrode material is selected from at least one of artificial graphite, natural graphite, lithium titanate, silicon-carbon composite material and silicon-oxygen composite material. Detailed Implementation

[0019] The non-aqueous electrolyte of the present invention can increase the ion transmission rate, improve the fast-charging cycle performance of lithium-ion batteries, and reduce internal resistance at the same time, and is particularly suitable for lithium-ion batteries using a ternary cathode material system (such as lithium nickel cobalt manganese oxide-based materials and lithium nickel cobalt aluminum oxide-based materials) in high-voltage systems. The lithium-ion battery of the present invention may comprise a cathode material, an anode material and the non-aqueous electrolyte. Wherein, the cathode material may comprise layered oxides (such as lithium nickel cobalt manganese oxide-based materials, lithium nickel cobalt aluminum oxide-based materials and lithium cobalt oxide-based materials), and olivine-type materials (lithium iron phosphate-based materials, lithium manganese iron phosphate-based materials). The electrolyte of the present invention is particularly suitable for lithium nickel cobalt manganese oxide-based materials and lithium nickel cobalt aluminum oxide-based materials with high energy density. Further, the lithium nickel cobalt manganese oxide-based materials may comprise lithium nickel cobalt manganese oxide, doped or coated lithium nickel cobalt manganese oxide, and the lithium nickel cobalt aluminum oxide-based materials may comprise lithium nickel cobalt aluminum oxide, doped or coated lithium nickel cobalt aluminum oxide. The chemical formula of the nickel cobalt manganese oxide is LiNi x Co y Mn z M (1-x-y-z) O2, and the chemical formula of the nickel cobalt aluminum oxide is LiNi x Co y Al z N (1-x-y-z) O2, wherein M is at least one selected from the group consisting of Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V and Ti, N is at least one selected from the group consisting of Mn, Mg, Cu, Zn, Sn, B, Ga, Cr, Sr, V and Ti, 0<x<1, 0<y<1, 0<z<1, and x+y+z≤1. Specifically, the cathode material may be LiNi8Co1Mn1O2, LiNi5Co2Mn3O2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2. The anode material is selected from at least one of artificial graphite, natural graphite, lithium titanate, silicon-carbon composite materials and silicon-oxygen composite materials.

[0020] The non-aqueous electrolyte comprises an electrolyte salt, a non-aqueous organic solvent and an additive.

[0021] Based on the mass of electrolyte salt, non-aqueous organic solvent, and additives as 100%, the mass percentage of electrolyte salt is 5-25%, further, 8-20%, and even further, 10-15%. As examples, the mass percentage of electrolyte salt may be, but is not limited to, 5%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 20%, and 25%. The mass percentage of electrolyte salt is not limited to the listed values; other unlisted values ​​within this range also apply. The electrolyte salt is selected from at least one of lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium fluorosulfonate, lithium difluorooxalatoborate (LiDFOB), lower aliphatic carboxylic acids, lithium difluorodioxalatophosphate (LiDFBP), and lithium bis(fluorosulfonyl)imide (LiFSI). As an example, lithium salt is lithium hexafluorophosphate (LiPF6), but not limited thereto. Furthermore, the lithium salt is a mixture of lithium hexafluorophosphate (LiPF6) and lithium bis(oxalato)borate (LiBOB).

[0022] The non-aqueous organic solvent is selected from γ-butyrolactone (GBL), γ-valerolactone (GVL), δ-valerolactone (DVL), methyl acetate (MA), ethyl acetate (EA), ethyl propionate (EP), butyl acetate (BAC), propyl propionate (PP), butyl propionate (PRB), ethylene carbonate (EC), propylene carbonate (PCA), butyl carbonate (BC), methyl pentyl carbonate (MPC), vinylene carbonate (VEC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), methyl propyl carbonate (MPC), and propylene carbonate (PC). At least one of 1,3-dioxolane (DOL), 1,4-dioxolane (DX), crown ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-CH3-THF), 2-trifluoromethyltetrahydrofuran (2-CF3-THF), dimethoxymethane (DMM), diethoxymethane (DEM), ethoxymethoxymethane (DCE), ethylene glycol di-n-propyl ether (EDP), ethylene glycol di-n-butyl ether (EDB), and diethylene glycol dimethyl ether (DEGME).

[0023] The mass percentage of the electrolyte salt, non-aqueous organic solvent, and additives is 100%, with the non-aqueous organic solvent accounting for 65-90% of the mass, preferably 75-89%. More preferably, the non-aqueous organic solvent accounts for 78-88% of the mass. As examples, the mass percentage of the non-aqueous organic solvent may be, but is not limited to, 65%, 68%, 70%, 73%, 75%, 78%, 80%, 83%, 85%, 87%, or 90%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0024] The additives include compound A, which has the structural formula shown in Formula 1, and compound B, which has the structural formula shown in Formula 2.

[0025]

[0026] Among them, R1, R2, R3, R4, and R5 are each independently selected from substituted or unsubstituted C1-C5 hydrocarbon groups and C1-C5 alkyl ketone groups; R6 and R7 are each independently selected from hydrogen, cyano, or cyano-substituted C1-C5 hydrocarbon groups; at least one of R1, R2, R3, R4, R5, R6, and R7 contains a cyano group; R8, R9, and R 10 Each is independently selected from substituted or unsubstituted C1-C5 hydrocarbon groups, R 11 The groups are selected from substituted or unsubstituted C1-C5 hydrocarbon groups and cyano groups. Further, R1, R2, R3, R4, and R5 are each independently selected from unsubstituted C1-C5 alkyl groups, cyano-substituted C1-C5 alkyl groups, and C1-C3 alkyl ketone groups; R6 and R7 are each independently selected from hydrogen and cyano groups; and R8, R9, and R... 10 Each alkyl group is independently selected from substituted or unsubstituted C1-C5 alkyl groups, R 11 Selected from unsubstituted C1-C5 alkyl, cyano, or alkylsilyl-substituted C1-C5 alkyl groups.

[0027] For example, R1, R2, R3, R4, and R5 are each independently selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, vinyl, propynyl, isopropynyl, butenyl, isobutenyl, pentenyl, isopentenyl, ethynyl, propynyl, isopropynyl, butynyl, isobutynyl, penynyl, isopentenyl, cyano-substituted methyl, cyano-substituted ethyl, cyano-substituted propyl, cyano-substituted isopropyl, cyano-substituted butyl, cyano-substituted isobutyl, and cyano-substituted pentyl. , cyano-substituted isopentyl, cyano-substituted vinyl, cyano-substituted propenyl, cyano-substituted isopropenyl, cyano-substituted butenyl, cyano-substituted isobutenyl, cyano-substituted pentenyl, cyano-substituted isopentenyl, cyano-substituted ethynyl, cyano-substituted propynyl, cyano-substituted isopropynyl, cyano-substituted butynyl, cyano-substituted isobutynyl, cyano-substituted penynyl, cyano-substituted isopentynyl, acetone, acetone, isoacetone, butanone, isobutanone, pentanone, isopentanone.

[0028] As an example, R6 and R7 are each independently selected from hydrogen, cyano, cyano-substituted methyl, cyano-substituted ethyl, cyano-substituted propyl, cyano-substituted isopropyl, cyano-substituted butyl, cyano-substituted isobutyl, cyano-substituted pentyl, cyano-substituted isopentyl, cyano-substituted vinyl, cyano-substituted propynyl, cyano-substituted isopropynyl, cyano-substituted butynyl, cyano-substituted isobutynyl, cyano-substituted pentynyl, cyano-substituted isopentynyl, cyano-substituted ethynyl, cyano-substituted propynyl, cyano-substituted isopropynyl, cyano-substituted butynyl, cyano-substituted isobutynyl, cyano-substituted pentynyl, and cyano-substituted isopentynyl.

[0029] As an example, R8, R9, R 10Each of these groups is independently selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, vinyl, propenyl, isopropenyl, butenyl, isobutenyl, pentenyl, isopentenyl, ethynyl, propynyl, isopropynyl, butynyl, isobutynyl, pentenyl, isopentenyl, cyano-substituted methyl, cyano-substituted ethyl, cyano-substituted propyl, cyano-substituted isopropyl, cyano-substituted butyl, cyano-substituted isobutyl, cyano-substituted pentyl, cyano-substituted isopentyl, cyano-substituted vinyl, cyano-substituted propenyl, cyano-substituted isopropenyl, cyano-substituted butenyl, cyano-substituted isobutenyl, cyano-substituted... The following are listed: pentenyl, cyano-substituted isopentenyl, cyano-substituted ethynyl, cyano-substituted propynyl, cyano-substituted isopropynyl, cyano-substituted butynyl, cyano-substituted isobutynyl, cyano-substituted penynyl, cyano-substituted isopentenyl, fluoromethyl, fluoroethyl, fluoropropyl, fluoroisopropyl, fluorobutyl, fluoroisobutyl, fluoropentyl, fluoroisopentyl, fluorovinyl, fluoropropenyl, fluoroisopropenyl, fluorobutenyl, fluoroisobutenyl, fluoropentenyl, fluoroethynyl, fluoropropynyl, fluoroisopropynyl, fluorobutynyl, fluoroisobutynyl, fluoropentynyl, fluoroisopentynyl.

[0030] As an example, R 11Selected from cyano, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, vinyl, propenyl, isopropenyl, butenyl, isobutenyl, pentenyl, isopentenyl, ethynyl, propynyl, isopropynyl, butynyl, isobutynyl, penynyl, isopentenyl, cyano-substituted methyl, cyano-substituted ethyl, cyano-substituted propyl, cyano-substituted isopropyl, cyano-substituted butyl, cyano-substituted isobutyl, cyano-substituted pentyl, cyano-substituted isopentyl, cyano-substituted vinyl, cyano-substituted propenyl, cyano-substituted The following are listed: isopropenyl, cyano-substituted butenyl, cyano-substituted isobutenyl, cyano-substituted pentenyl, cyano-substituted isopentenyl, cyano-substituted ethynyl, cyano-substituted propynyl, cyano-substituted isopropynyl, cyano-substituted butynyl, cyano-substituted isobutynyl, cyano-substituted penynyl, cyano-substituted isopentenyl, trisylmethyl-substituted methyl, trisylmethyl-substituted ethyl, trisylmethyl-substituted propyl, trisylmethyl-substituted isopropyl, trisylmethyl-substituted butyl, trisylmethyl-substituted isobutyl, trisylmethyl-substituted pentyl, trisylmethyl-substituted isopentenyl Trisylmethyl substituted vinyl, trisylmethyl substituted propenyl, trisylmethyl substituted isopropenyl, trisylmethyl substituted butenyl, trisylmethyl substituted isobutenyl, trisylmethyl substituted alkenyl, trisylmethyl substituted isopentenyl, trisylmethyl substituted ethynyl, trisylmethyl substituted propynyl, trisylmethyl substituted isopropynyl, trisylmethyl substituted butynyl, trisylmethyl substituted isobutynyl, trisylethyl substituted pentyynyl, trisylethyl substituted isopentenyl, trisylethyl substituted ethyl, trisylethyl substituted propyl, trisylethyl substituted isopropyl Trisylethyl-substituted butyl, trisylethyl-substituted isobutyl, trisylethyl-substituted pentyl, trisylethyl-substituted isopentyl, trisylethyl-substituted vinyl, trisylethyl-substituted propynyl, trisylethyl-substituted isopropynyl, trisylethyl-substituted butenyl, trisylethyl-substituted isobutenyl, trisylethyl-substituted alkenyl, trisylethyl-substituted isopentenyl, trisylethyl-substituted ethynyl, trisylethyl-substituted propynyl, trisylethyl-substituted isopropynyl, trisylethyl-substituted butynyl, trisylethyl-substituted isobutynyl, trisylethyl-substituted pentynyl, trisylethyl-substituted isopentenyl.

[0031] Furthermore, compound A is selected from at least one of compounds one through three.

[0032]

[0033] CAS No.: 55726-81-3 CAS No.: 58720-06-2 CAS No.: 59061-05-1 Compound B is selected from at least one of compounds four through six.

[0034]

[0035] CAS No.: 42437-75-2 CAS No.: 66055-10-5 CAS No.: 59061-05-1 Based on the mass of electrolyte salt, non-aqueous organic solvent, and additives as 100%, compound A accounts for 0.05~2.00% of the mass, and compound B accounts for 0.05~2.00% of the mass. Further, compound A accounts for 0.1~2.0% of the sum of the mass of lithium salt, non-aqueous organic solvent, and additives; even further, compound A accounts for 0.1~1.0% of the sum of the mass of lithium salt, non-aqueous organic solvent, and additives. As examples, compound A accounts for 0.05%, 0.10%, 0.20%, 0.30%, 0.40%, 0.50%, 0.60%, 0.70%, 0.80%, 0.90%, 1.00%, 1.50%, and 2.00% of the sum of the mass of lithium salt, non-aqueous organic solvent, and additives, but is not limited to the listed values; other unlisted values ​​within this range also apply. Furthermore, compound B accounts for 0.1 to 2.0% of the total mass of the lithium salt, non-aqueous organic solvent, and additives. More specifically, compound B accounts for 0.1 to 1.0% of the total mass of the lithium salt, non-aqueous organic solvent, and additives. As examples, compound B accounts for 0.05%, 0.10%, 0.20%, 0.30%, 0.40%, 0.50%, 0.60%, 0.70%, 0.80%, 0.90%, 1.00%, 1.50%, and 2.00% of the total mass of the lithium salt, non-aqueous organic solvent, and additives, but is not limited to the listed values; other unlisted values ​​within this range also apply.

[0036] Furthermore, the additive may also include an auxiliary agent selected from at least one of fluoroethylene carbonate (FEC), vinylene carbonate (VC), 1,3-propanesulfonic acid lactone (PS), vinyl sulfate (DTD), 1,3-propanediol cyclosulfate (PCS), 1,4-butanesulfonic acid lactone, triallyl phosphate (TAP), and succinic anhydride. The auxiliary agent constitutes 0.05 to 5.00% of the total mass of the lithium salt, non-aqueous organic solvent, and additive. Further, the auxiliary agent constitutes 0.1 to 4.0% of the total mass of the lithium salt, non-aqueous organic solvent, and additive; even further, the auxiliary agent constitutes 0.5 to 3.0% of the total mass of the lithium salt, non-aqueous organic solvent, and additive. As an example, the additives account for 0.05%, 0.1%, 0.2%, 0.4%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, and 5% of the total mass of the lithium salt, non-aqueous organic solvent, and additives, but are not limited to the listed values; other unlisted values ​​within this range also apply.

[0037] To further illustrate the purpose, technical solution, and beneficial effects of this invention, the following will provide a further description of the invention in conjunction with specific embodiments. It should be noted that, for other raw materials in the embodiments and comparative examples where specific conditions are not specified, they can be carried out under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used where the manufacturer is not specified are all commercially available conventional products.

[0038] Example 1 1.1 Preparation of Electrolyte In an argon atmosphere and a vacuum glove box with a moisture content of <1ppm, ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed in a weight ratio of EC:EMC=3:7. Then, various additives are added, dissolved, and stirred thoroughly before LiPF6 is added. After mixing evenly, a non-aqueous electrolyte is obtained.

[0039] 1.2 Preparation of the positive electrode LiNi nickel cobalt manganese oxide material LiNi 0.6 Co 0.2 Mn 0.2 The binder PVDF and the conductive agent SuperP are mixed evenly at a mass ratio of 96:2.5:1.5 to prepare a lithium secondary battery positive electrode slurry with a certain viscosity. The mixed slurry is coated on both sides of aluminum foil, dried, and rolled to obtain the positive electrode sheet.

[0040] 1.3 Preparation of negative electrode sheet A lithium secondary battery negative electrode slurry of a certain viscosity is prepared by uniformly mixing graphite, PVDF binder and SuperP conductive agent at a mass ratio of 90:2:8. The mixed slurry is then coated on both sides of copper foil, dried and rolled to obtain the negative electrode sheet.

[0041] 1.4 Preparation of Lithium-ion Batteries The positive electrode, separator, and negative electrode are stacked in sequence, and then layered as needed. After the tabs are welded, they are placed in the aluminum-plastic film of the battery outer packaging. The prepared non-aqueous electrolyte is injected into the dried bare cell. Vacuum sealing, standing, formation (0.05C constant current charging to 3.9V, then 0.1C constant current charging to 4.4V), shaping, and capacity testing are performed sequentially to obtain a 1Ah soft-pack lithium secondary battery.

[0042] The composition and content of the electrolytes in Examples 1-8 and Comparative Examples 1-3 are shown in Table 1. The preparation processes of the lithium-ion battery electrolytes, positive electrode sheets, negative electrode sheets, and lithium-ion batteries in Examples 2-8 and Comparative Examples 1-3 are the same as those in Example 1.

[0043] Table 1. Composition of the electrolytes in Examples 1-8 and Comparative Examples 1-3

[0044] The lithium-ion batteries prepared in Examples 1-8 and Comparative Examples 1-3 were subjected to performance tests under the following conditions, and the results are shown in Table 2.

[0045] (1) High-temperature cycling performance test The lithium-ion battery was placed in a 45°C constant temperature chamber and allowed to stand for 30 minutes to reach a constant temperature. It was then charged at a constant current of 2C until the voltage reached 4.4V, followed by constant voltage charging at 4.4V until the current reached 0.05C. Next, it was discharged at a constant current of 2C until the voltage reached 3.0V. The first discharge capacity was recorded as C0, constituting one charge-discharge cycle. Then, 800 cycles of 2C / 2C charge and discharge were performed at 45°C, with the discharge capacity recorded as C1. The capacity retention rate of the lithium-ion battery was calculated using the following formula.

[0046] Capacity retention rate = C1 / C0 × 100% (2) AC impedance performance test The lithium-ion battery was placed in a 25°C constant temperature chamber and allowed to stand for 30 minutes to reach a constant temperature. It was then charged at a constant current of 0.33C to a voltage of 4.4V, followed by a constant voltage charge of 4.4V to a current of 0.05C. Next, it was discharged at a constant current of 0.33C to a voltage of 3.0V, and the first discharge capacity was recorded as 100% SOC. The battery was then charged again at a constant current of 0.33C to a voltage of 4.4V, followed by a constant voltage charge of 4.4V to a current of 0.05C, and finally discharged at a constant current of 0.33C to 50%, obtaining the Rct value for 50% SOC. The electrochemical impedance spectroscopy (EIS) was measured using an electrochemical workstation with an open-circuit voltage, an amplitude of 10 mV, and a frequency range of 0.01Hz to 1000000Hz.

[0047] Table 2 Performance test results of lithium-ion batteries in Examples 1-8 and Comparative Examples 1-3

[0048] As can be seen from the results in Table 2, at a high voltage of 4.4V, Examples 1-8 exhibited better high-temperature cycling and lower internal resistance, which is attributed to the synergistic effect of the xylose compounds with cyano groups and the phosphorimine compounds.

[0049] Furthermore, comparing Examples 1-5, it is evident that Compound A (Compound 1) and Compound B (Compound 4) exhibit superior performance. This is because the multiple -CN groups in Compound 1 can generate strong coordination chelation with nickel and cobalt transition metal ions, effectively suppressing the dissolution of transition metals from the positive electrode surface under high voltage. However, its steric hindrance is relatively large, limiting its ability to modify the negative electrode SEI film when used alone, making it difficult to fully suppress side reactions. However, under the synergistic effect of Compound B, it can significantly improve high-temperature cycling performance and reduce DCR internal resistance. This is because the P=N bonds in Compound 4 can preferentially undergo reduction and decomposition on the negative electrode surface, generating a highly flexible SEI film containing PO and PN components, thereby reducing charge transfer impedance.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A non-aqueous electrolyte, comprising a lithium salt, a non-aqueous organic solvent, and additives, characterized in that, The additive comprises compound A with the structural formula shown in Formula 1 and compound B with the structural formula shown in Formula 2, wherein R1, R2, R3, R4, and R5 are each independently selected from substituted or unsubstituted C1-C5 hydrocarbon groups and C1-C5 alkyl ketone groups; R6 and R7 are each independently selected from hydrogen-, cyano-, or cyano-substituted C1-C5 hydrocarbon groups; at least one of R1, R2, R3, R4, R5, R6, and R7 contains a cyano group; and R8, R9, and R... 10 Each is independently selected from substituted or unsubstituted C1-C5 hydrocarbon groups, R 11 Selected from substituted or unsubstituted C1-C5 hydrocarbon groups and cyano groups. 。 2. The non-aqueous electrolyte according to claim 1, characterized in that, R1, R2, R3, R4, and R5 are each independently selected from unsubstituted C1-C5 alkyl groups, cyano-substituted C1-C5 alkyl groups, and C1-C3 alkyl ketone groups; R6 and R7 are each independently selected from hydrogen and cyano groups; R8, R9, and R... 10 Each alkyl group is independently selected from substituted or unsubstituted C1-C5 alkyl groups, R 11 Selected from unsubstituted C1-C5 alkyl, cyano, or alkylsilyl-substituted C1-C5 alkyl groups.

3. The non-aqueous electrolyte according to claim 1, characterized in that, Compound A is selected from at least one of compounds one through three. 。 4. The non-aqueous electrolyte according to claim 1, characterized in that, Compound B is selected from at least one of compounds four to six. 。 5. The non-aqueous electrolyte according to claim 1, characterized in that, Based on the mass of the electrolyte salt, the non-aqueous organic solvent, and the additive being 100%, the mass percentage of compound A is 0.05~2.00%, and the mass percentage of compound B is 0.05~2.00%.

6. The non-aqueous electrolyte according to claim 1, characterized in that, The electrolyte salt is a lithium salt, which is selected from at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(oxalate-borate), lithium difluorophosphate, lithium fluorosulfonate, lithium difluorooxalate-borate, lithium lower aliphatic carboxylic acids, lithium difluorodioxalate phosphate, and lithium bis(oxalate-imide).

7. The non-aqueous electrolyte according to claim 1, characterized in that, The non-aqueous organic solvent is selected from at least one of γ-butyrolactone, γ-valerolactone, δ-valerolactone, methyl acetate, ethyl acetate, ethyl propionate, butyl acetate, propyl propionate, butyl propionate, ethylene carbonate, propylene carbonate, butyl carbonate, methyl pentyl carbonate, vinylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, propylene carbonate, 1,3-dioxolane, 1,4-dioxane, crown ether, tetrahydrofuran, 2-methyltetrahydrofuran, 2-trifluoromethyltetrahydrofuran, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether.

8. A lithium-ion battery, comprising a positive electrode material, a negative electrode material, and an electrolyte, characterized in that, The electrolyte is selected from the non-aqueous electrolyte described in any one of claims 1 to 7.

9. The lithium-ion battery according to claim 8, characterized in that, The cathode material is selected from at least one of lithium nickel cobalt manganese oxide materials and lithium nickel cobalt aluminum oxide materials.

10. The lithium-ion battery according to claim 8, characterized in that, The negative electrode material is selected from at least one of artificial graphite, natural graphite, lithium titanate, silicon-carbon composite material, and silicon-oxygen composite material.

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