Non-aqueous electrolyte, lithium-ion battery, battery module, battery pack and power-consuming device

Abstract

The present invention relates to the field of battery technology, and in particular to a non-aqueous electrolyte, a lithium-ion battery, a battery module, a battery pack and an electrical device. The non-aqueous electrolyte comprises a non-aqueous organic solvent, a lithium salt and a functional additive, wherein the functional additive comprises a compound having a structure shown in Formula I. When the electrolyte additive of the present invention is used in a lithium-ion battery, it can achieve a synergistic effect between the non-aqueous organic solvent, the lithium salt and the functional additive, form a stable solid electrolyte interface between the electrolyte and the electrode through an electrochemical reaction, effectively inhibit the side reaction of the electrolyte on the surface of the electrode, inhibit the dissolution of transition metals, reduce impedance, and improve the comprehensive performance of the lithium-ion battery.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a non-aqueous electrolyte, a lithium-ion battery, a battery module, a battery pack and an electrical device. Background Art

[0002] In order to cope with the increasingly severe environmental pollution and energy crisis, people's demand for green energy is constantly rising. With the vigorous development of clean energy in recent years, such as the large-scale promotion and application of electric vehicles, mobile electronic devices, home-type intelligence and energy storage systems, the comprehensive performance requirements of lithium-ion batteries are also increasing, accompanied by a significant increase in the safety and stability requirements of battery devices to prevent battery abuse and give the battery a longer service life. Generally, the introduction of functional additives in the electrolyte is considered to be one of the effective ways to improve the comprehensive performance of lithium-ion batteries. However, the commonly used functional additives currently have other problems while improving the performance of lithium-ion batteries: for example, vinyl sulfate is a commonly used electrolyte additive that can participate in the formation of negative electrode SEI film, improve the stability of graphite negative electrode, and improve the storage and cycle performance of lithium-ion batteries, but its disadvantages are poor storage stability and easy decomposition and discoloration; 1,3-propane sultone can form a film on the negative electrode, inhibit gas production, and improve the cycle life of lithium-ion batteries, but it has a strong carcinogenic risk; vinylene carbonate can polymerize into a film on the negative electrode, reduce self-discharge, and improve the cycle performance of lithium-ion batteries, but it will increase impedance. Additives with a single function or electrolytes with a complex formula combination will cause the battery performance to be insufficient and fail to achieve the purpose of use.

[0003] Therefore, there is an urgent need to develop a non-aqueous electrolyte that can effectively improve the high-temperature storage and cycle performance of lithium-ion batteries through the synergistic effect between various components. Summary of the invention

[0004] In view of the shortcomings of the prior art mentioned above, the object of the present invention is to provide a non-aqueous electrolyte, a lithium ion battery, a battery module, a battery pack and an electrical device. When the electrolyte additive of the present invention is used in a lithium ion battery, it can achieve a synergistic effect between the non-aqueous organic solvent, the lithium salt and the functional additive, form a stable solid electrolyte interface between the electrolyte and the electrode through an electrochemical reaction, effectively inhibit the side reactions of the electrolyte on the surface of the electrode, inhibit the dissolution of transition metals, reduce impedance, and improve the comprehensive performance of the lithium ion battery.

[0005] To achieve the above-mentioned object and other related objects, the first aspect of the present invention provides a non-aqueous electrolyte, comprising a non-aqueous organic solvent, a lithium salt and a functional additive, wherein the functional additive comprises a compound having a structure shown in Formula I,

[0006] ;

[0007] Wherein, R1, R2, R3, and R4 are each independently selected from any one of hydrogen, carbonyl, substituted or unsubstituted C1-C10 straight or branched alkyl, substituted or unsubstituted C2-C10 alkenyl, substituted or unsubstituted C2-C10 alkynyl, and substituted or unsubstituted C1-C10 alkoxy; or R3 and R4 are bonded to form a bridged ring; A is selected from O, S, SO, or SO2.

[0008] A second aspect of the present invention provides a lithium ion battery comprising a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and the non-aqueous electrolyte of the first aspect of the present invention.

[0009] A third aspect of the present invention provides a battery module, comprising the lithium-ion battery described in the second aspect of the present invention.

[0010] A fourth aspect of the present invention provides a battery pack, comprising the battery module described in the third aspect of the present invention.

[0011] The fifth aspect of the present invention provides an electrical device, comprising the lithium-ion battery described in the second aspect of the present invention, wherein the lithium-ion battery is used as a power source for the electrical device, and the electrical device includes a mobile device, an electric vehicle, an electric train, a satellite, a ship, and an energy storage system.

[0012] Compared with the prior art, the beneficial effects of the present invention are:

[0013] (1) The compound having the structure shown in Formula I used in the present invention has a lower LUMO energy level, can preferentially form a stable and uniform solid electrolyte interface (SEI film) on the surface of the negative electrode, can effectively inhibit the side reaction of the electrolyte on the surface of the electrode, is conducive to the deintercalation of lithium ions, reduces lithium deposition, and reduces impedance;

[0014] (2) The cyclic sulfate structure in the compound of formula I can undergo an electrochemical reaction on the negative electrode side to form a conductive interface containing lithium sulfate salt, which is an effective SEI film component; the cyclic ether structure can decompose at the negative electrode to form a polymer structure similar to PEO, which is beneficial to the rapid transmission of lithium ions, thereby reducing impedance;

[0015] (3) The compound of the structure shown in Formula I can produce a synergistic effect with other active ingredients in the electrolyte; the compound of the structure shown in Formula I can preferentially form a film on the negative electrode, and at the same time can inhibit the reaction of other additives, play a role in protecting other additives, and enable other additives to continue to act in the electrolyte, thereby improving the long-cycle performance; it can improve the compatibility of the electrolyte and the negative electrode material, achieve an increase in the battery rate and long cycle life, and enhance the overall performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1It is a comparison chart of the lithium ion electrolytes obtained in Examples 1 and 2 and Comparative Example 1 after being placed at room temperature for 14 days.

[0017] Figure 2 The compound 1 synthesized in Example 1 is shown 13 C-NMR spectrum.

[0018] Figure 3 The compound 1 synthesized in Example 1 is shown 1 H-NMR spectrum.

[0019] Figure 4 The compound 6 synthesized in Example 2 is shown 13 C-NMR spectrum.

[0020] Figure 5 The compound 6 synthesized in Example 2 is shown 1 H-NMR spectrum.

[0021] Figure 6 The compound 7 synthesized in Example 3 is shown 13 C-NMR spectrum.

[0022] Figure 7 The compound 7 synthesized in Example 3 is shown 1 H-NMR spectrum.

[0023] Figure 8 The compound 8 synthesized in Example 4 is shown 13 C-NMR spectrum.

[0024] Fig. 9 The compound 8 synthesized in Example 4 is shown 1 H-NMR spectrum.

[0025] Fig.10 It is shown that the compound 13 synthesized in Example 5 13 C-NMR spectrum.

[0026] Fig.11 It is shown that the compound 13 synthesized in Example 5 1 H-NMR spectrum.

[0027] Fig.12 The compound 14 synthesized in Example 6 is shown 13 C-NMR spectrum.

[0028] Fig.13 The compound 14 synthesized in Example 6 is shown 1 H-NMR spectrum.

[0029] Fig.14The compound 17 synthesized in Example 7 is shown 13 C-NMR spectrum.

[0030] Fig.15 It is shown that the compound 17 synthesized in Example 7 1 H-NMR spectrum. DETAILED DESCRIPTION

[0031] Hereinafter, embodiments of the non-aqueous electrolyte, lithium-ion battery, battery module, battery pack, and electrical device provided by the present invention will be described in detail.

[0032] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The range defined in this way can be inclusive or exclusive of end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that a range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, wherein a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0033] After extensive research, the inventors of the present invention provide a non-aqueous electrolyte and a lithium-ion battery, a battery module, a battery pack, and an electrical device. In the non-aqueous electrolyte of the present application, the components of the electrolyte cooperate with each other, which can not only form a dense, uniform, and structurally stable solid electrolyte interface on the surface of the positive and negative electrodes, but also effectively improve the high-temperature storage and cycle performance of the lithium-ion battery. On this basis, the present application is completed.

[0034]

Non-aqueous electrolyte

[0035] The first aspect of the present invention provides a non-aqueous electrolyte, characterized in that it includes a non-aqueous organic solvent, a lithium salt and a functional additive, wherein the functional additive includes a compound having a structure shown in Formula I.

[0036] The compound of the structure shown in Formula I is:

[0037] ;

[0038] Wherein, R1, R2, R3, and R4 are each independently selected from any one of hydrogen, carbonyl, substituted or unsubstituted C1-C10 straight or branched alkyl, substituted or unsubstituted C2-C10 alkenyl, substituted or unsubstituted C2-C10 alkynyl, and substituted or unsubstituted C1-C10 alkoxy; or R3 and R4 are bonded to form a bridged ring; A is selected from O, S, SO, or SO2.

[0039] The compound of the structure shown in Formula I of the present invention can preferentially form a stable, uniform and lithium sulfate-rich SEI film on the surface of the negative electrode, which can effectively inhibit the side reactions of the electrolyte on the surface of the electrode, is conducive to the deintercalation of lithium ions, reduces lithium deposition, and reduces impedance.

[0040] In the compound of the structure represented by formula I of the present invention, R1, R2, R3 and R4 are independently selected from hydrogen.

[0041] In the compound of the structure represented by formula I of the present invention, R1, R2, R3 and R4 are each independently selected from a carbonyl group.

[0042] In the compound of the structure shown in Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C1-C10 straight or branched alkyl groups. In a specific embodiment, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C1-C8, C1-C6, C1-C4, or C1-C2 straight or branched alkyl groups. Optionally, R1, R2, R3, and R4 are each independently selected from methyl, ethyl, propyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, or sec-butyl. Optionally, the alkyl group may be substituted, and the substituent may be, for example, fluorine, chlorine, bromine, iodine, methoxy, siloxane, trifluoromethyl, trifluoromethoxy, cyano, and the like.

[0043] In the compound of the structure shown in Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C2-C10 alkenyl groups. In a specific embodiment, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C2-C8, C2-C6, or C2-C4 alkenyl groups. Optionally, R1, R2, R3, and R4 are each independently selected from vinyl, propenyl, isopropenyl, butenyl, isobutenyl, tert-butenyl, or sec-butenyl. Optionally, the alkenyl group may be substituted, and the substituent may be, for example, fluorine, chlorine, bromine, iodine, methoxy, siloxane, trifluoromethyl, trifluoromethoxy, cyano, and the like.

[0044] In the compound of the structure shown in Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C2-C10 alkynyl groups. In a specific embodiment, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C2-C8, C2-C6, or C2-C4 alkynyl groups. Optionally, R1, R2, R3, and R4 are each independently selected from ethynyl, propynyl, isopropynyl, butynyl isobutynyl, tert-butynyl, or sec-butynyl. Optionally, the alkynyl group may be substituted, and the substituent may be, for example, fluorine, chlorine, bromine, iodine, methoxy, siloxane, trifluoromethyl, trifluoromethoxy, cyano, and the like.

[0045] In the compound of the structure shown in Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C1-C10 alkoxy groups. In a specific embodiment, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C1-C8, C1-C6, C1-C4, or C1-C2 alkoxy groups. Optionally, the alkoxy group may be substituted, and the substituent may be, for example, fluorine, chlorine, bromine, iodine, siloxane, trifluoromethyl, trifluoromethoxy, cyano, etc.

[0046] In the compound of the structure represented by formula I of the present invention, R3 and R4 are bonded to form a bridge ring.

[0047] In the compound of the structure represented by formula I of the present invention, A is selected from O, S, SO or SO2.

[0048] In some optional embodiments of the present invention, R1, R2, R3, and R4 are each independently selected from any one of hydrogen, carbonyl, substituted or unsubstituted C1-C4 straight or branched alkyl, substituted or unsubstituted C2-C4 alkenyl, substituted or unsubstituted C2-C4 alkynyl, and substituted or unsubstituted C1-C4 alkoxy; or R3 and R4 are bonded to form a bridged ring.

[0049] In some optional embodiments of the present invention, R1, R2, R3, and R4 are each independently selected from any one of hydrogen, carbonyl, substituted or unsubstituted C1-C2 straight or branched alkyl, substituted or unsubstituted C2-C3 alkenyl, substituted or unsubstituted C2-C3 alkynyl, and substituted or unsubstituted C1-C2 alkoxy; or R3 and R4 are bonded to form a bridged ring.

[0050] In some optional embodiments of the present invention, R1, R2, R3, and R4 are each independently selected from any one of hydrogen, carbonyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, methoxy-substituted methyl, vinyl, propenyl, ethynyl, propynyl, methoxy, and ethoxy; or R3 and R4 are bonded to form a bridged ring.

[0051] In some optional embodiments of the present invention, R1, R2, R3, and R4 are each independently selected from hydrogen, carbonyl, methyl, ethyl, vinyl, ethynyl, methoxy, and methoxy-substituted methyl, or R3 and R4 are bonded to form a bridged ring.

[0052] In the non-aqueous electrolyte provided by the present invention, further, the compound of the structure represented by formula I is selected from the following structures:

[0053] ;

[0054] ;

[0055] .

[0056] In the non-aqueous electrolyte provided by the present invention, the functional additive in the non-aqueous electrolyte may include the compound represented by Formula I, or may include any one or more combinations of the compounds represented by Compounds 1 to 17.

[0057] In the non-aqueous electrolyte provided by the present invention, preferably, the compound having the structure shown in Formula I is selected from tetrahydrofurano[3,4-d]-1,3,2-dioxathiolane-2, 2-dioxide (the structural formula is shown in Compound 1), 4-vinyltetrahydrofurano[3,4-d]-1,3,2-dioxathiolane-2, 2-dioxide (the structural formula is shown in Compound 6), 4,6-divinyltetrahydrofurano[3,4-d]-1,3,2-dioxathiolane-2, 2-dioxide (the structural formula is shown in Compound 7), 4-ethynyltetrahydrofurano[3,4-d]-1,3,2-dioxathiolane-2, 2-dioxide (the structural formula is shown in Compound 8), 3a,4,7,7a-tetrahydrofurano[4,7-epoxybenzo[d]1,3,2-dioxathiolane-2, 2-dioxide (the structural formula is shown in Compound 9), 2-dioxide (the structural formula is shown in compound 13), dihydrofurano[3,4-d]-1,3,2-dioxathiolane-4 (3aH)-one 2,2-dioxide (the structural formula is shown in compound 14), cyclopentane[3,4-d]-1,3,2-dioxathiolane-2,2-dioxide (the structural formula is shown in compound 17) or more thereof.

[0058] Specifically, the following structure is preferred:

[0059] .

[0060] In the non-aqueous electrolyte provided by the present invention, the mass proportion of the compound of the structure shown in Formula I in the non-aqueous electrolyte is 0.5% to 3%. In some embodiments, the mass proportion of the compound of the structure shown in Formula I in the non-aqueous electrolyte may also be 0.5% to 1%, 0.5% to 1.5%, 0.5% to 2%, 0.5% to 2.5%, 1% to 1.5%, 1% to 2%, 1% to 2.5%, 1% to 3%, 1.5% to 2.5%, 1.5% to 2%, 2% to 2.5% or 2.5% to 3%, etc. Within the above range, the compound of the structure shown in Formula I can form a stable and uniform solid electrolyte interface on the surface of the negative electrode, which can effectively inhibit the side reaction of the electrolyte on the surface of the electrode, is conducive to the deintercalation of lithium ions, reduces lithium deposition, and reduces impedance; if the proportion of the compound of the structure shown in Formula I is too high (the mass proportion in the non-aqueous electrolyte is higher than 3%), it will cause the negative electrode film to be too thick, significantly increase the negative electrode interface impedance, and cause the battery performance to deteriorate. If the proportion of the compound of the structure represented by Formula I is too low (less than 0.5% by mass in the non-aqueous electrolyte), it will lead to poor film-forming effect and no obvious improvement on the performance such as circulation and high-temperature storage.

[0061] The non-aqueous electrolyte provided by the present invention also includes other additives, and the other additives are selected from lithium bis(fluorosulfonyl)imide, tetravinylsilane, lithium trifluoromethylsulfonate, lithium fluorosulfonate, methanesulfonic acid-2-propynyl alcohol, methanedisulfonic acid methylene ester, N-methyldi(fluorosulfonyl)imide, 4,5-dicyano-2-methylimidazole and 4,5-dicyano-2-ethylimidazole. Preferably, the other additives are selected from lithium bis(fluorosulfonyl)imide, tetravinylsilane, lithium trifluoromethylsulfonate, lithium fluorosulfonate, methanesulfonic acid-2-propynyl alcohol, methanedisulfonic acid methylene ester, N-methyldi(fluorosulfonyl)imide, 4,5-dicyano-2-methylimidazole and 4,5-dicyano-2-ethylimidazole. When the compound of the structure shown in Formula I is used in conjunction with other active ingredients in the electrolyte, the performance of the lithium ion battery can be further improved. Specifically: the other additives of the present invention can cooperate with the compound of the structure shown in Formula I to have obvious synergistic effect. The compound of the structure shown in Formula I can preferentially form a film on the negative electrode, and at the same time can inhibit the reaction of other additives and play a role in protecting other additives; it can allow other additives to continue to act in the electrolyte and improve the long cycle performance; it can improve the compatibility of the electrolyte and the negative electrode material, achieve an increase in the battery rate and long cycle life, and enhance the comprehensive performance of the battery.

[0062] In the non-aqueous electrolyte provided by the present invention, the other additives account for 1% to 5% by mass of the non-aqueous electrolyte. In some embodiments, the other additives may also account for 1% to 4%, 1% to 3%, 2% to 4%, 1% to 2%, 2% to 3%, 3% to 4% or 4% to 5% by mass of the non-aqueous electrolyte, for example. Within the above range, other additives can stably form films on the surfaces of the positive and negative electrodes, inhibit gas production, and reduce impedance. If the proportion of the other additives is too high (the mass proportion in the non-aqueous electrolyte is higher than 5%), the film may be too thick and the impedance may increase. If the proportion of the other additives is too low (the mass proportion in the non-aqueous electrolyte is lower than 1%), the film-forming effect is poor, the interfacial impedance cannot be effectively reduced, and the improvement of the battery performance is not obvious.

[0063] Further optionally, the other additives are selected from lithium bis(fluorosulfonyl)imide (LiFSI) and lithium fluorosulfonate (LiFS), and the mass proportion of the lithium bis(fluorosulfonyl)imide in the non-aqueous electrolyte is 0.5% to 3%, which can be selected from 0.5% to 1%, 0.5% to 1.5%, 0.5% to 2%, 0.5% to 2.5%, 1% to 1.5%, 1% to 2%, 1% to 2.5%, 1% to 3%, 1.5% to 2.5%, 1.5% to 2%, 2% to 2.5% or 2.5% to 3%, etc. The mass proportion of the lithium fluorosulfonate in the non-aqueous electrolyte is 0.5% to 3%, which can be optionally 0.5% to 1%, 0.5% to 1.5%, 0.5% to 2%, 0.5% to 2.5%, 1% to 1.5%, 1% to 2%, 1% to 2.5%, 1% to 3%, 1.5% to 2.5%, 1.5% to 2%, 2% to 2.5% or 2.5% to 3%, etc.

[0064] In the non-aqueous electrolyte provided by the present invention, the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorosilicate, lithium aluminum tetrachloride, lithium bis(oxalatoborate), lithium chloride, lithium bromide, lithium iodide, lithium trifluoromethanesulfonate, and lithium bis(trifluoromethanesulfonate)imide. Preferably, the lithium salt is selected from lithium hexafluorophosphate.

[0065] In the non-aqueous electrolyte provided by the present invention, the concentration of the lithium salt in the non-aqueous electrolyte is 0.5 mol / L to 2 mol / L. In some embodiments, the concentration of the lithium salt in the non-aqueous electrolyte may also be 0.5 mol / L to 1 mol / L, 1 mol / L to 1.5 mol / L or 1.5 mol / L to 2 mol / L, etc. Within the above range, high lithium ion conductivity and stable lithium ion transmission can be guaranteed. If the proportion of the lithium salt is too high (the content in the non-aqueous electrolyte is higher than 2 mol / L), the lithium salt will be incompletely dissociated, and the viscosity of the electrolyte will be too high, which will hinder the transmission of lithium ions and reduce the rate performance and low temperature performance. If the proportion of the lithium salt is too low (the content in the non-aqueous electrolyte is lower than 0.5 mol / L), the electrolyte will have poor electrochemical stability.

[0066] In the non-aqueous electrolyte provided by the present invention, the non-aqueous organic solvent is selected from cyclic carbonates and / or chain carbonates. Optionally, the non-aqueous organic solvent is selected from one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, and γ-butyrolactone. Further optionally, the non-aqueous organic solvent is selected from ethyl methyl carbonate and ethylene carbonate, and the volume ratio of ethyl methyl carbonate to ethylene carbonate is (6-8): (2-4). It can be selected as (6-7): (3-4) or (7-8): (2-3).

[0067] In the non-aqueous electrolyte provided by the present invention, the mass proportion of the non-aqueous organic solvent in the non-aqueous electrolyte is 72% to 93%. In some embodiments, the mass proportion of the non-aqueous organic solvent in the non-aqueous electrolyte may also be 72% to 75%, 75% to 85%, or 85% to 93%, etc. Within the above range, lithium salts and additives can be dissolved well. If the proportion of the non-aqueous organic solvent is too high (the mass proportion in the non-aqueous electrolyte is higher than 93%), the electrochemical stability of the electrolyte will be poor. If the proportion of the non-aqueous organic solvent is too low (the mass proportion in the non-aqueous electrolyte is lower than 72%), the lithium salt will be incompletely dissociated and the viscosity of the electrolyte will be too high.

[0068]

Lithium-ion battery

[0069] A second aspect of the present invention provides a lithium ion battery, the lithium ion battery further comprising a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte, the non-aqueous electrolyte being the non-aqueous electrolyte of the first aspect of the present invention.

[0070] The positive electrode includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector. The positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The positive electrode active material layer includes a positive electrode active material, and the positive electrode active material layer may also include a conductive agent and a binder. The positive electrode active material may be selected from a combination of one or more of lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate and lithium iron manganese phosphate. Preferably, the positive electrode active material used in this experiment is selected from lithium iron phosphate. Those skilled in the art may select conductive agents and binders suitable for lithium ion batteries in the art. Among them, the conductive agent may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers. The binder may include, for example, at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0071] In some embodiments, the positive electrode can be prepared in the following manner: the components for preparing the positive electrode, such as the positive electrode material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode can be obtained.

[0072] The negative electrode includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector. The negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base material. The negative electrode active material layer includes a negative electrode active material, and the negative electrode active material layer may also include a plasticizer, a conductive agent and a binder. The negative electrode active material may be selected from a combination of one or more of silicon carbon, silicon oxygen, natural graphite, artificial graphite, lithium titanate, amorphous carbon and lithium metal. Those skilled in the art may select plasticizers, conductive agents and binders suitable for lithium ion batteries in the art. Among them, the conductive agent may be selected, for example, from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), carboxymethyl chitosan (CMCS), and sodium carboxymethyl cellulose (CMC-Na).

[0073] In some embodiments, the negative electrode can be prepared in the following manner: the above-mentioned components for preparing the negative electrode, such as the negative electrode material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode can be obtained.

[0074] The lithium-ion battery provided in the second aspect of the present invention can be prepared by a method known in the art. For example, the positive electrode, the separator, and the negative electrode are stacked in order, so that the separator is between the positive and negative electrodes to play an isolating role, and then the sheets are stacked to obtain a bare cell; the bare cell is placed in an outer packaging shell, dried, and then injected with a non-aqueous electrolyte, and a lithium-ion battery is obtained through vacuum packaging, standing, forming, shaping, and other processes.

[0075]

Battery module

[0076] The third aspect of the present invention provides a battery module, which includes any one or more lithium-ion batteries described in the second aspect of the present invention. The number of lithium-ion batteries in the battery module can be adjusted according to the application and capacity of the battery module.

[0077]

Battery Pack

[0078] The fourth aspect of the present invention provides a battery pack, which includes any one or more battery modules described in the third aspect of the present invention. That is, the battery pack includes any one or more lithium-ion batteries described in the second aspect of the present invention.

[0079] The number of battery modules in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0080]

Electrical devices

[0081] The fifth aspect of the present invention provides an electric device, which includes any one or more lithium-ion batteries described in the second aspect of the present invention. The lithium-ion battery can be used as a power source for the electric device. Preferably, the electric device can be, but is not limited to, a mobile device (such as a mobile phone, a laptop computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc.

[0082] The beneficial effects of the present invention are further illustrated below in conjunction with embodiments.

[0083] In order to make the invention purpose, technical scheme and beneficial technical effect of the present invention clearer, the present invention is further described in detail below in conjunction with examples. However, it should be understood that the examples of the present invention are only for explaining the present invention, not for limiting the present invention, and the examples of the present invention are not limited to the examples given in the specification. The specific experimental conditions or operating conditions not specified in the examples are made under conventional conditions, or are made under the conditions recommended by the material supplier.

[0084] In addition, it should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before or after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified; it should also be understood that the combination connection relationship between one or more devices / electrical devices mentioned in the present invention does not exclude the existence of other devices / devices before or after the combination device / device or the insertion of other devices / devices between these two explicitly mentioned devices / devices, unless otherwise specified. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or the scope of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the present invention without substantially changing the technical content.

[0085] In the following examples, the reagents, materials and instruments used are all commercially available unless otherwise specified.

[0086] The positive electrode material of the lithium-ion battery used in the embodiments and comparative examples of the present invention is lithium iron phosphate, and the negative electrode is graphite. The capacity of each battery is 1Ah, and the electrolyte injection amount is 4g. The following different electrolytes are selected as embodiments and comparative examples.

[0087] Example 1

[0088] (1) Preparation of compounds:

[0089] Preparation method of tetrahydrofuran [3,4-d] -1,3,2-dioxathiolane-2, 2-dioxide (Compound 1):

[0090] At room temperature, cis-tetrahydrofuran-3, 4-diol (20 g, 0.19 mol, 1.0 equiv) was dissolved in 200 mL of anhydrous acetonitrile, and N, N-thiodiimidazole (45.7 g, 0.23 mmol, 1.2 equiv) was added thereto, and the mixture was stirred at room temperature for reaction. Filter, the filtrate was concentrated under reduced pressure, and the residue was dissolved in dichloromethane and water, separated, and the organic phase was washed with water, washed with saturated sodium chloride, and dried over anhydrous magnesium sulfate. The organic phase was filtered, the filtrate was concentrated under reduced pressure, and the residue was dissolved in an appropriate amount of dichloromethane to cool and precipitate solids, which were filtered and dried under vacuum to obtain the product compound 1 (26 g, 81%) as a white powdery solid.

[0091] like Figure 2 and 3 , Spectral characterization of tetrahydrofuran [3,4-d] -1,3,2-dioxathiolane-2, 2-dioxide (Compound 1):

[0092] 1 H NMR (400 MHz, CDCl3): δ 5.42-5.38 (m, 2H), 4.32 (m, 2H), 3.74-3.69(m, 2H);

[0093] 13 C NMR (101 MHz, CDCl3): δ 83.1, 72.1.

[0094] (2) Preparation of electrolyte:

[0095] An electrolyte (oxygen content <0.1ppm, water content <0.1ppm) was prepared in a glove box, and ethyl methyl carbonate (EMC) and ethylene carbonate (EC) were mixed in a volume ratio of 7:3 as an organic solvent, and a total of 100mL was prepared. LiPF6 with a lithium salt molar concentration of 1.1mol / L was added to the solvent, and 1% of the total mass of the solvent and lithium salt was added to the above electrolyte. Lithium bis(fluorosulfonyl)imide (LiFSI), 1% of lithium fluorosulfonate (LiFS) and 1% of tetrahydrofuran [3,4-d]-1,3,2-dioxathiolane-2, 2-dioxide (Compound 1) were added, and stirred until completely dissolved to obtain the lithium ion battery electrolyte of Example 1.

[0096] (3) Preparation of lithium-ion batteries:

[0097] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery cell to be injected with liquid is obtained. The lithium ion battery electrolyte of Example 1 is injected to obtain the lithium ion battery C1 of Example 1.

[0098] Embodiment 2:

[0099] (1) Preparation of compounds:

[0100] Preparation method of 4-vinyltetrahydrofuran [3,4-d] -1,3,2-dioxathiolane-2,2-dioxide (Compound 6):

[0101] 2-vinyltetrahydrofuran-3, 4-diol (25 g, 0.19 mol, 1.0 equiv) and imidazole (32 g, 0.47 mol, 2.5 equiv) were dissolved in 150 mL of anhydrous acetonitrile. The mixture was cooled to -40°C, and SO2Cl2 (17 mL, MW / 135, d / 1.667, 0.21 mol, 1.1 equiv) was slowly added dropwise thereto while stirring. The reaction mixture was stirred at -40°C for about 2 hours, and then naturally warmed to room temperature and continued to stir for 1 hour. The solvent was evaporated by concentration under reduced pressure, and dichloromethane and water were added to dissolve the liquid. The organic phase was washed with water, washed with saturated sodium chloride, and dried over anhydrous magnesium sulfate. The organic phase was filtered, the filtrate was concentrated under reduced pressure, and the residue was dissolved in an appropriate amount of dichloromethane and cooled to precipitate a solid. The product compound 6 (20 g, 48%) was obtained as a white powdery solid after filtration and vacuum drying.

[0102] like Figure 4 and 5 , Spectral characterization of 4-vinyltetrahydrofuran [3,4-d]-1,3,2-dioxathiolane-2, 2-dioxide (Compound 6):

[0103] 1 H NMR (400 MHz, CDCI3): δ 6.05 (m,1H), 5.56-5.40 (m, 4H), 4.45 (m,1H), 3.85-3.72 (m, 2H);

[0104] 13 C NMR (101 MHz, CDC13): δ 140.3, 123.5, 92.1, 80.7, 77.3, 74.3.

[0105] (2) Preparation of electrolyte:

[0106] Different from Example 1, 1% of Compound 1 was replaced by 1% of Compound 6 to obtain the lithium ion battery electrolyte of Example 2.

[0107] (3) Preparation of lithium-ion batteries:

[0108] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery cell to be injected with liquid is obtained. The lithium ion battery electrolyte of Example 2 is injected to obtain the lithium ion battery C2 of Example 2.

[0109] Embodiment 3:

[0110] (1) Preparation of compounds:

[0111] Preparation method of 4,6-divinyltetrahydrofuran [3,4-d] -1,3,2-dioxathiolane-2,2-dioxide (Compound 7):

[0112] 2,3-Divinyl-tetrahydrofuran-3, 4-diol (20 g, 0.13 mol, 1.0 equiv) and TMEDA (28 mL, 0.19 mol, 1.5 equiv) were dissolved in 150 mL of anhydrous acetonitrile, cooled to about 0°C, and sulfuryl fluoride gas was slowly introduced into the mixture under stirring until the raw material was completely converted. The filtrate was concentrated under reduced pressure, and the residue was dissolved in dichloromethane and water. The organic phase was separated, and the organic phase was washed with water, saturated sodium chloride, and dried over anhydrous magnesium sulfate. The organic phase was filtered, the filtrate was concentrated under reduced pressure, and the residue was dissolved in an appropriate amount of dichloromethane to cool and precipitate a solid. The product compound 7 (18 g, 63%) was obtained as a white powdery solid after filtration and vacuum drying.

[0113] like Figure 6 and 7 , Spectral characterization of 4,6-divinyltetrahydrofuran[3,4-d]-1,3,2-dioxathiolane-2, 2-dioxide (Compound 7):

[0114] 1 H NMR (400 MHz, CDCI3): δ 6.05 (m,2H), 5.48-5.35 (m, 4H), 4.35 (m,2H), 3.80-3.68 (m, 2H);

[0115] 13 C NMR (101 MHz, CDC13): δ 138.6, 120.7, 96.1, 77.3.

[0116] (2) Preparation of electrolyte:

[0117] Different from Example 1, 1% of Compound 1 was replaced by 1% of Compound 7 to obtain the lithium ion battery electrolyte of Example 3.

[0118] (3) Preparation of lithium-ion batteries:

[0119] The lithium-ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery cell to be injected with liquid is obtained. The lithium-ion battery electrolyte of Example 3 is injected to obtain the lithium-ion battery C3 of Example 3.

[0120] Embodiment 4:

[0121] (1) Preparation of compounds:

[0122] Preparation method of 4-ethynyltetrahydrofuran [3,4-d] -1,3,2-dioxathiolane-2,2-dioxide (Compound 8):

[0123] 2-Ethynyltetrahydrofuran-3, 4-diol (15 g, 0.12 mol, 1.0 equiv) and TMEDA (20 mL, 0.14 mol, 1.2 equiv) were dissolved in 100 mL of anhydrous acetonitrile, cooled to about 0°C, and sulfuryl fluoride gas was slowly introduced into the mixture under stirring until the raw material was completely converted. The filtrate was concentrated under reduced pressure, and the residue was dissolved in dichloromethane and water. The organic phase was separated, and the organic phase was washed with water, saturated sodium chloride, and dried over anhydrous magnesium sulfate. The organic phase was filtered, the filtrate was concentrated under reduced pressure, and the residue was dissolved in an appropriate amount of dichloromethane to cool and precipitate a solid. The product compound 8 (16 g, 61%) was obtained as a white powdery solid after filtration and vacuum drying.

[0124] like Figure 8 and 9 , Spectral characterization of 4-ethynyltetrahydrofuran[3,4-d]-1,3,2-dioxathiolane-2, 2-dioxide (Compound 8):

[0125] 1 H NMR (400 MHz, CDCl3): δ 5.32-5.18 (m, 1H), 5.30 (d, J = 6.0 Hz, 1H), 4.82 (d, J = 10.0 Hz, 1H), 4.24-4.08 (m, 2H), 3.84 (s, 1H);

[0126] 13 C NMR (101 MHz, CDC13): δ 83.5, 82.8, 80.1, 78.6, 73.1.

[0127] (2) Preparation of electrolyte:

[0128] Different from Example 1, 1% of Compound 1 was replaced by 1% of Compound 8 to obtain the lithium ion battery electrolyte of Example 4.

[0129] (3) Preparation of lithium-ion batteries:

[0130] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery cell to be injected with liquid is obtained. The lithium ion battery electrolyte of Example 4 is injected to obtain the lithium ion battery C4 of Example 4.

[0131] Embodiment 5:

[0132] (1) Preparation of compounds:

[0133] Preparation method of 3a,4,7,7a-tetrahydrofuran-4,7-epoxybenzo[d]1,3,2-dioxathiolane-2,2-dioxide (Compound 13):

[0134] Referring to the preparation method in Example 1, the reaction substrate was replaced to obtain compound 13.

[0135] like Fig.10 and 11 , Spectral characterization of 3a,4,7,7a-tetrahydrofuran-4,7-epoxybenzo[d]1,3,2-dioxathiolane-2,2-dioxide (Compound 13):

[0136] 1 H NMR (400 MHz, CDCl3): δ 5.95-5.72 (m, 2H), 4.75-4.58 (m, 2H), 4.56-4.40 (m, 2H);

[0137] 13 C NMR (101 MHz, CDCl3): δ 138.6, 89.3, 80.8.

[0138] (2) Preparation of electrolyte:

[0139] Different from Example 1, 1% of Compound 1 is replaced by 1% of Compound 13 to obtain the lithium ion battery electrolyte of Example 5.

[0140] (3) Preparation of lithium-ion batteries:

[0141] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery cell to be injected with liquid is obtained. The lithium ion battery electrolyte of Example 5 is injected to obtain the lithium ion battery C5 of Example 5.

[0142] Embodiment 6:

[0143] (1) Preparation of compounds:

[0144] Preparation method of dihydrofuran [3,4-d] -1,3,2-dioxathiolane-4 (3aH) -one 2,2-dioxide (Compound 14):

[0145] Referring to the preparation method in Example 1, the reaction substrate was replaced to obtain compound 14.

[0146] like Fig.12 and 13 , Spectral characterization of dihydrofurano[3,4-d]-1,3,2-dioxathiolane-4 (3aH)-one 2,2-dioxide (Compound 14):

[0147] 1 H NMR (400 MHz, CDCl3): δ 5.57-5.55 (m, 1H), 5.30 (d, J = 6.4 Hz, 1H), 4.70 (d, J = 12.0 Hz, 1H), 4.66-4.61 (m, 1H);

[0148] 13 C NMR (101 MHz, CDCl3): δ 173.4, 84.3, 73.1, 65.2.

[0149] (2) Preparation of electrolyte:

[0150] Different from Example 1, 1% of Compound 1 was replaced by 1% of Compound 14 to obtain the lithium ion battery electrolyte of Example 6.

[0151] (3) Preparation of lithium-ion batteries:

[0152] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery cell to be injected with liquid is obtained. The lithium ion battery electrolyte of Example 6 is injected to obtain the lithium ion battery C6 of Example 6.

[0153] Embodiment 7:

[0154] (1) Preparation of compounds:

[0155] Preparation method of sulfolane [3,4-d]-1,3,2-dioxathiolane-2,2-dioxide (Compound 17):

[0156] Referring to the preparation method in Example 1, the reaction substrate was replaced to obtain Compound 17.

[0157] like Fig.14 and 15 , Spectral characterization of cyclopentane [3,4-d]-1,3,2-dioxathiolane-2, 2-dioxide (Compound 17):

[0158] 1 H NMR (400 MHz, CDCl3): δ 5.15-4.8 (m, 2H), 3.85-3.68 (m, 2H), 3.56-3.40 (m, 2H);

[0159] 13 C NMR (101 MHz, CDCl3): δ 84.3, 68.8.

[0160] (2) Preparation of electrolyte:

[0161] Different from Example 1, 1% of Compound 1 was replaced by 1% of Compound 17 to obtain the lithium ion battery electrolyte of Example 7.

[0162] (3) Preparation of lithium-ion batteries:

[0163] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery cell to be injected with liquid is obtained. The lithium ion battery electrolyte of Example 7 is injected to obtain the lithium ion battery C7 of Example 7.

[0164] Embodiment 8:

[0165] (1) Preparation of electrolyte:

[0166] Different from Example 1, 1% of Compound 1 is replaced by 0.5% of Compound 1 to obtain the lithium ion battery electrolyte of Example 8.

[0167] (2) Preparation of lithium-ion batteries:

[0168] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery cell to be injected with liquid is obtained. The lithium ion battery electrolyte of Example 8 is injected to obtain the lithium ion battery C8 of Example 8.

[0169] Embodiment 9:

[0170] (1) Preparation of electrolyte:

[0171] Different from Example 1, 1% of Compound 1 is replaced by 2% of Compound 1 to obtain the lithium ion battery electrolyte of Example 9.

[0172] (2) Preparation of lithium-ion batteries:

[0173] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery cell to be injected with liquid is obtained. The lithium ion battery electrolyte of Example 9 is injected to obtain the lithium ion battery C9 of Example 9.

[0174] Embodiment 10:

[0175] (1) Preparation of electrolyte:

[0176] Different from Example 1, 1% of LiFS is replaced by 0.5% of LiFS to obtain the lithium ion battery electrolyte of Example 10.

[0177] (2) Preparation of lithium-ion batteries:

[0178] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery core to be injected with liquid is obtained. The lithium ion battery electrolyte of Example 10 is injected to obtain the lithium ion battery C10 of Example 10.

[0179] Embodiment 11:

[0180] (1) Preparation of electrolyte:

[0181] Different from Example 1, 1% of LiFS is replaced by 2% of LiFS to obtain the lithium ion battery electrolyte of Example 11.

[0182] (2) Preparation of lithium-ion batteries:

[0183] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery cell to be injected with liquid is obtained. The lithium ion battery electrolyte of Example 11 is injected to obtain the lithium ion battery C11 of Example 11.

[0184] Embodiment 12:

[0185] (1) Preparation of electrolyte:

[0186] Different from Example 1, 1% of LiFSI is replaced by 0.5% of LiFSI to obtain the lithium ion battery electrolyte of Example 12.

[0187] (2) Preparation of lithium-ion batteries:

[0188] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery cell to be injected with liquid is obtained. The lithium ion battery electrolyte of Example 12 is injected to obtain the lithium ion battery C12 of Example 12.

[0189] Embodiment 13:

[0190] (1) Preparation of electrolyte:

[0191] Different from Example 1, 1% of LiFSI is replaced by 2% of LiFSI to obtain the lithium ion battery electrolyte of Example 13.

[0192] (2) Preparation of lithium-ion batteries:

[0193] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery cell to be injected with liquid is obtained. The lithium ion battery electrolyte of Example 13 is injected to obtain the lithium ion battery C13 of Example 13.

[0194] Embodiment 14:

[0195] (1) Preparation of electrolyte:

[0196] Different from Example 1, 1% of LiFSI and 1% of LiFS are replaced by 0.5% of LiFSI and 0.5% of LiFS to obtain the lithium ion battery electrolyte of Example 14.

[0197] (2) Preparation of lithium-ion batteries:

[0198] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery cell to be injected with liquid is obtained. The lithium ion battery electrolyte of Example 14 is injected to obtain the lithium ion battery C14 of Example 14.

[0199] Embodiment 15:

[0200] (1) Preparation of electrolyte:

[0201] Different from Example 1, 1% LiFSI and 1% LiFS are replaced by 2% LiFSI and 2% LiFS to obtain the lithium ion battery electrolyte of Example 15.

[0202] (2) Preparation of lithium-ion batteries:

[0203] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery cell to be injected with liquid is obtained. The lithium ion battery electrolyte of Example 15 is injected to obtain the lithium ion battery C15 of Example 15.

[0204] Comparative Example 1:

[0205] (1) Preparation of electrolyte:

[0206] Prepare an electrolyte (oxygen content <0.1ppm, water content <0.1ppm) in a glove box, mix ethyl methyl carbonate (EMC) and ethylene carbonate (EC) in a volume ratio of 7:3 as an organic solvent, and prepare a total of 100mL. Add LiPF6 with a lithium salt molar concentration of 1.1mol / L to the solvent, add 1% of the total mass of the solvent and lithium salt lithium bis(fluorosulfonyl)imide (LiFSI) and 1% of lithium fluorosulfonate (LiFS) to the above electrolyte, respectively, stir until completely dissolved, and obtain the lithium ion battery electrolyte of Comparative Example 1.

[0207] (2) Preparation of lithium-ion batteries:

[0208] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery core to be injected with liquid is obtained. The lithium ion battery electrolyte of Comparative Example 1 is injected to obtain the lithium ion battery CC1 of Comparative Example 1.

[0209] Comparative Example 2:

[0210] (1) Preparation of electrolyte:

[0211] Different from Comparative Example 1, 0.2% of Compound 1 is further added to obtain the lithium ion battery electrolyte of Comparative Example 2.

[0212] (2) Preparation of lithium-ion batteries:

[0213] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery core to be injected with liquid is obtained. The lithium ion battery electrolyte of Comparative Example 2 is injected to obtain the lithium ion battery CC2 of Comparative Example 2.

[0214] Comparative Example 3:

[0215] (1) Preparation of electrolyte:

[0216] Different from Comparative Example 1, 4% of Compound 1 is further added to obtain the lithium ion battery electrolyte of Comparative Example 3.

[0217] (2) Preparation of lithium-ion batteries:

[0218] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery core to be injected with liquid is obtained. The lithium ion battery electrolyte of Comparative Example 3 is injected to obtain the lithium ion battery CC3 of Comparative Example 3.

[0219] Comparative Example 4:

[0220] (1) Preparation of electrolyte:

[0221] Different from Comparative Example 1, 1% of LiFS is replaced by 5% of LiFS and 1% of Compound 1 to obtain the lithium ion battery electrolyte of Comparative Example 4.

[0222] (2) Preparation of lithium-ion batteries:

[0223] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery core to be injected with liquid is obtained. The lithium ion battery electrolyte of Comparative Example 4 is injected to obtain the lithium ion battery CC4 of Comparative Example 4.

[0224] Comparative Example 5:

[0225] (1) Preparation of electrolyte:

[0226] Different from Comparative Example 1, 1% of LiFSI is replaced by 5% of LiFSI and 1% of Compound 1 to obtain the lithium ion battery electrolyte of Comparative Example 5.

[0227] (2) Preparation of lithium-ion batteries:

[0228] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery core to be injected with liquid is obtained. The electrolyte of the lithium ion battery of Comparative Example 5 is injected to obtain the lithium ion battery CC5 of Comparative Example 5.

[0229] Comparative Example 6:

[0230] (1) Preparation of electrolyte:

[0231] Different from Comparative Example 1, 0.2% LiFSI, 0.2% LiFS and 1% Compound 1 were added to the above electrolyte respectively based on the total mass of solvent and lithium salt to obtain the lithium ion battery electrolyte of Comparative Example 6.

[0232] (2) Preparation of lithium-ion batteries:

[0233] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery core to be injected with liquid is obtained. The lithium ion battery electrolyte of Comparative Example 6 is injected to obtain the lithium ion battery CC6 of Comparative Example 6.

[0234] Comparative Example 7:

[0235] (1) Preparation of electrolyte:

[0236] Different from Comparative Example 1, 1% of 1,3-propane sultone (PS) is further added to obtain the lithium ion battery electrolyte of Comparative Example 7.

[0237] (2) Preparation of lithium-ion batteries:

[0238] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery core to be injected with liquid is obtained. The lithium ion battery electrolyte of Comparative Example 7 is injected to obtain the lithium ion battery CC7 of Comparative Example 7.

[0239] Comparative Example 8:

[0240] (1) Preparation of electrolyte:

[0241] Different from Comparative Example 1, 1% of diethyl sulfate (DTD) is further added to obtain the lithium ion battery electrolyte of Comparative Example 8.

[0242] (2) Preparation of lithium-ion batteries:

[0243] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery core to be injected with liquid is obtained. The electrolyte of the lithium ion battery of Comparative Example 8 is injected to obtain the lithium ion battery CC8 of Comparative Example 8.

[0244] Comparative Example 9:

[0245] (1) Preparation of electrolyte:

[0246] Different from Comparative Example 1, 1% of methylene disulfonate (MMDS) is further added to obtain the lithium ion battery electrolyte of Comparative Example 9.

[0247] (2) Preparation of lithium-ion batteries:

[0248] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery core to be injected with liquid is obtained. The lithium ion battery electrolyte of Comparative Example 9 is injected to obtain the lithium ion battery CC9 of Comparative Example 9.

[0249] Comparative Example 10:

[0250] (1) Preparation of electrolyte:

[0251] Different from Comparative Example 1, 1% of vinylene carbonate (VC) is further added to obtain the lithium ion battery electrolyte of Comparative Example 10.

[0252] (2) Preparation of lithium-ion batteries:

[0253] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery core to be injected with liquid is obtained. The lithium ion battery electrolyte of Comparative Example 10 is injected to obtain the lithium ion battery CC10 of Comparative Example 10.

[0254] Comparative Example 11:

[0255] (1) Preparation of electrolyte:

[0256] Different from Comparative Example 1, 1% of LiFS is replaced by 1% of VC and 1% of Compound 1 to obtain the lithium ion battery electrolyte of Comparative Example 11.

[0257] (2) Preparation of lithium-ion batteries:

[0258] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery core to be injected with liquid is obtained. The lithium ion battery electrolyte of Comparative Example 11 is injected to obtain the lithium ion battery CC11 of Comparative Example 11.

[0259] Comparative Example 12:

[0260] (1) Preparation of electrolyte:

[0261] Different from Comparative Example 1, 1% of LiFS was replaced by 1% of Compound 1 to obtain the lithium ion battery electrolyte of Comparative Example 12.

[0262] (2) Preparation of lithium-ion batteries:

[0263] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery core to be injected with liquid is obtained. The lithium ion battery electrolyte of Comparative Example 12 is injected to obtain the lithium ion battery CC12 of Comparative Example 12.

[0264] Comparative Example 13:

[0265] (1) Preparation of electrolyte:

[0266] Different from Comparative Example 1, 1% of LiFSI is replaced by 1% of Compound 1 to obtain the lithium ion battery electrolyte of Comparative Example 13.

[0267] (2) Preparation of lithium-ion batteries:

[0268] The lithium ion battery used in this embodiment has lithium iron phosphate as the positive electrode active material and graphite as the negative electrode active material. After the battery is subjected to pulping, coating, rolling, die cutting, lamination, hot pressing and packaging processes, a dry battery core to be injected with liquid is obtained. The lithium ion battery electrolyte of Comparative Example 13 is injected to obtain the lithium ion battery CC13 of Comparative Example 13.

[0269] The following experiments were performed on the batteries obtained in Examples 1 to 15 and Comparative Examples 1 to 13. The test results are shown in Table 1.

[0270] (1) High temperature cycle performance test: The batteries obtained in Examples 1 to 15 and Comparative Examples 1 to 13 were charged at 1C constant current and constant voltage at 45°C to a voltage of 3.65V and a cut-off current of 0.05C, left for 10 min, and discharged at 1C constant current to 2.5V. The above is one charge and discharge cycle. The obtained batteries were cyclically charged and discharged at 45°C, and the cycle was terminated when the discharge capacity was less than 80% of the initial discharge capacity.

[0271] (2) High temperature storage performance test: The batteries obtained in Examples 1 to 15 and Comparative Examples 1 to 13 were charged at 1C constant current and constant voltage at 25°C to a voltage of 3.65V and a cut-off current of 0.05C, and the 1C capacity Q and battery thickness H were recorded respectively; the fully charged batteries were stored at 60°C for 14 days, and the battery 1C discharge capacity Q1 and battery thickness H1 were recorded at 25°C; the batteries were charged at 1C constant current and constant voltage to a voltage of 3.65V and a cut-off current of 0.05C, and then discharged at 1C constant current to 2.5V, and the 1C discharge capacity Q2 was recorded, and the capacity retention rate, recovery rate and battery expansion rate of the batteries after storage were calculated;

[0272] The calculation formulas are as follows:

[0273] Storage capacity retention rate = Q1 / Q×100%; storage capacity recovery rate = Q2 / Q×100%; storage battery expansion rate = (H1-H) / H×100%.

[0274] Table 1

[0275]

[0276] By comparing Examples 1 to 15 with Comparative Examples 1, 12 to 13, it can be seen that the compound of the structure shown in Formula I of the present invention can be used in conjunction with other additives to effectively improve the high temperature storage and cycle performance of lithium ion batteries; by comparing Examples 1, 8 to 15 with Comparative Examples 2 to 6, it can be seen that the addition of too much or too little of the compound of the structure shown in Formula I or other additives does not significantly improve or deteriorates the performance of lithium ion batteries; by comparing Example 1 with Comparative Examples 7 to 11, it can be seen that the compound of the structure shown in Formula I improves the performance of lithium ion batteries better than commonly used functional additives; by comparing Examples 1 to 7 with Comparative Example 8, it can be seen that the performance of the compound of the structure shown in Formula I is slightly better than that of vinyl sulfate, and the compound of the structure shown in Formula I has stable physical properties and is not easy to decompose and discolor compared to vinyl sulfate, such as Figure 1 shown.

[0277] In summary, the electrolyte additive with the structure shown in Formula I can preferentially form a stable solid electrolyte interface on the surface of the positive and negative electrodes, effectively inhibit the side reactions of the electrolyte on the surface of the electrode, and reduce the battery impedance. The electrolyte additive with the structure shown in Formula I has a synergistic effect with other main components in the electrolyte, which can further improve the high temperature storage and cycle performance of lithium-ion batteries.

[0278] The above is only a preferred embodiment of the present invention, and is not any formal or substantial limitation of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the method of the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any technician familiar with this profession, without departing from the spirit and scope of the present invention, can make some changes, modifications and evolutions of the technical content disclosed above, which are equivalent embodiments of the present invention; at the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A non-aqueous electrolyte, characterized in that: The invention comprises a non-aqueous organic solvent, a lithium salt and a functional additive, wherein the functional additive comprises a compound having a structure shown in formula I, ； in, R1, R2, R3, and R4 are each independently selected from any one of hydrogen, carbonyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, methoxy-substituted methyl, vinyl, propenyl, ethynyl, propynyl, methoxy, and ethoxy; or R3 and R4 are bonded to form a bridged ring; A is selected from O, S, SO or SO2; The mass proportion of the compound represented by the structure of Formula I in the non-aqueous electrolyte is 0.5% to 3%; The functional additives also include other additives, and the mass proportion of the other additives in the non-aqueous electrolyte is 1% to 5%; the other additives are selected from lithium bis(fluorosulfonyl)imide and lithium fluorosulfonate.

2. The non-aqueous electrolyte according to claim 1, characterized in that The compound represented by the formula I is selected from any one or more of the following structures: ； ； 。 3. The non-aqueous electrolyte according to claim 1, characterized in that The lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorosilicate, lithium aluminum tetrachloride, lithium bis(oxalatoborate), lithium chloride, lithium bromide, lithium iodide, lithium trifluoromethanesulfonate, and lithium bis(trifluoromethanesulfonate)imide; and / or, the concentration of the lithium salt in the non-aqueous electrolyte is 0.5 mol / L to 2 mol / L; And / or, the non-aqueous organic solvent is selected from cyclic carbonates and / or chain carbonates; And / or, the mass proportion of the non-aqueous organic solvent in the non-aqueous electrolyte is 72% to 93%.

4. The non-aqueous electrolyte according to claim 3, characterized in that The non-aqueous organic solvent is selected from one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, and γ-butyrolactone.

5. A lithium ion battery, characterized in that: The invention comprises a positive electrode, a negative electrode, a separator arranged between the positive electrode and the negative electrode, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte is the non-aqueous electrolyte according to any one of claims 1 to 4.

6. The lithium-ion battery according to claim 5, characterized in that: The negative electrode comprises a negative electrode active material, and the negative electrode active material is selected from a combination of one or more of silicon carbon, silicon oxygen, natural graphite, artificial graphite, lithium titanate, amorphous carbon and lithium metal; And / or, the positive electrode includes a positive electrode active material, and the positive electrode active material is selected from a combination of one or more of lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate and lithium iron manganese phosphate.

7. A battery module, characterized in that: Comprising a lithium ion battery according to claim 5 or 6.

8. A battery pack, characterized in that: Comprising the battery module according to claim 7.

9. An electrical device, characterized in that: It comprises a lithium-ion battery according to claim 5 or 6, wherein the lithium-ion battery is used as a power source for the device, and the power-consuming device includes a mobile device, an electric vehicle, an electric train, a satellite, a ship and an energy storage system.

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