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

Abstract

The invention relates to the technical field of batteries, in particular to a non-aqueous electrolyte, a lithium ion battery, a battery module, a battery pack and an electric device. The non-aqueous electrolyte comprises a lithium salt, a solvent and a functional additive, and the functional additive comprises a cyclic silica structure as shown in a formula I, 2-trifluoromethyl-1, 3-allyl sultone (TFMPS) and vinylene carbonate (VC); according to the invention, the cycle performance and the high-temperature and high-pressure performance of the lithium ion battery can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, 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] With the rapid development of new energy vehicles, consumers have higher demands for the endurance and safety performance of lithium-ion batteries. However, lithium-ion battery fires and explosions still occur frequently when new energy vehicles are charging or in collisions, which seriously threatens the safety of consumers' lives and property. As an important component of lithium-ion batteries, the thermal stability of the electrolyte largely determines the safety performance of the battery. Therefore, improving the thermal stability of the electrolyte and thus improving the safety performance of lithium-ion batteries is crucial. Rationally combining functional additives is one of the effective strategies to improve electrolyte stability and enhance the cycle performance and safety performance of lithium-ion batteries.

[0003] Based on this, the present invention designs a non-aqueous electrolyte for lithium-ion batteries with high thermal stability by rationally matching lithium salts, solvents and additives, so that the lithium-ion battery has excellent high-temperature performance and cycle performance. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, 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, which can effectively improve the cycle performance and high-temperature and high-pressure performance of the lithium-ion battery.

[0005] To achieve the above-mentioned and other related objects, the first aspect of the present invention provides a non-aqueous electrolyte, comprising a lithium salt, a solvent, and a functional additive, wherein the functional additive comprises a cyclic silicon-oxygen structure represented by Formula I, 2-trifluoromethyl-1,3-propene sultone (TFMPS), and vinylene carbonate (VC);

[0006]

[0007] In Formula I, R1, R2, R3, and R4 are each independently selected from hydrogen, halogen, cyano, substituted or unsubstituted linear or branched alkyl, substituted or unsubstituted unsaturated hydrocarbon, substituted or unsubstituted alkoxy, substituted or unsubstituted siloxy, substituted or unsubstituted silanyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocyclic, substituted or unsubstituted aryl, substituted or unsubstituted aryloxy, substituted or unsubstituted heteroaryl, substituted or unsubstituted aldehyde, substituted or unsubstituted keto, or substituted or unsubstituted ester.

[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 according to 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 present invention has the following beneficial effects:

[0013] (1) The silicon-oxygen bond (Si-O) in the cyclic silicon-oxygen structure has high oxidation resistance and will also react with HF and PF5 in the electrolyte, eliminating the damage of acidic substances to the interface film. The three-dimensional cross-linked network structure formed by the silicon-carbon bond (Si-C) can simultaneously improve the flexibility and ionic conductivity of the SEI film. In addition, the combination with cyanide can complex the positive electrode to produce transition metal ions; the combination with benzene ring can improve the oxidation resistance of the electrolyte and have a certain anti-overcharge ability; the combination with fluorine substituents can enhance its electronegativity, causing it to decompose earlier on the electrode surface to form a complete and dense SEI film.

[0014] (2) 2-Trifluoromethyl-1,3-propene sultone (TFMPS) has a lower LUMO energy level and can form a SEI film rich in (sulfite) and oligomers on the negative electrode surface before the electrolyte, effectively improving the ionic conductivity of the SEI film. Vinylene carbonate forms a highly elastic interfacial film covering the electrode surface through self-polymerization, ensuring that the electrode is not affected by the volume effect during the charge and discharge cycle, thereby improving the cycle life of the battery cell. DETAILED DESCRIPTION

[0015] 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.

[0016] The "ranges" disclosed herein are defined in terms of lower and upper limits, where a given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this manner can be inclusive or exclusive of the end values ​​and can be combined arbitrarily, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise indicated, the numerical range "a to b" is a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this 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.

[0017] In order to effectively improve the cycle performance and high-temperature and high-pressure performance of lithium-ion batteries, the present invention combines various beneficial groups on the basis of leveraging the advantages of siloxane compounds themselves to achieve an improvement in the comprehensive performance of a single additive, and combines other film-forming additives, solvents and lithium salts to provide a non-aqueous electrolyte for lithium-ion batteries.

[0018]

Non-aqueous electrolyte

[0019] A first aspect of the present invention provides a non-aqueous electrolyte, comprising a lithium salt, a solvent, and a functional additive, wherein the functional additive comprises a cyclic silicon-oxygen structure represented by Formula I, 2-trifluoromethyl-1,3-propene sultone, and vinylene carbonate;

[0020]

[0021] In Formula I, R1, R2, R3, and R4 are each independently selected from hydrogen, halogen, cyano, substituted or unsubstituted linear or branched alkyl, substituted or unsubstituted unsaturated hydrocarbon, substituted or unsubstituted alkoxy, substituted or unsubstituted siloxy, substituted or unsubstituted silanyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocyclic, substituted or unsubstituted aryl, substituted or unsubstituted aryloxy, substituted or unsubstituted heteroaryl, substituted or unsubstituted aldehyde, substituted or unsubstituted keto, or substituted or unsubstituted ester.

[0022] The cyclic silicon-oxygen structure shown in Formula I of the present invention has a high HOMO energy level and a low LUMO energy level, and can form a dense and uniform interfacial film on the surface of the positive and negative electrodes in advance of the electrolyte. The silicon-oxygen bond (Si-O) has high oxidation resistance and can also react with HF and PF5 produced by the hydrolysis of LiPF6 to prevent corrosion of the SEI film. At the same time, the silicon-carbon bond (Si-C) can polymerize to form a three-dimensional cross-linked network structure, which not only increases the flexibility of the SEI film, but also improves the ionic conductivity of the SEI film; 2-trifluoromethyl-1,3-propene sultone (TFMPS) can decompose to form inorganic sulfate and LiF, further improving the ionic conductivity of the SEI film; vinylene carbonate (VC) can decompose to form a highly elastic organic interfacial film. The combination of the three has a significant effect on improving the high-temperature performance, high-voltage resistance, and low-temperature performance of lithium-ion batteries.

[0023] In the cyclic silicon-oxygen structure represented by formula I of the present invention, R1, R2, R3, and R4 are each independently selected from hydrogen.

[0024] In the cyclic silicon-oxygen structure represented by formula I of the present invention, R1, R2, R3 and R4 are independently selected from halogen.

[0025] In the cyclic silicon-oxygen structure represented by formula I of the present invention, R1, R2, R3 and R4 are each independently selected from cyano groups.

[0026] In the cyclic silicon-oxygen structure represented by Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted linear or branched alkyl group. Alternatively, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C1-C10 linear or branched alkyl group. In specific embodiments, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C1-C6, C1-C4, or C1-C2 linear or branched alkyl group. Alternatively, R1, R2, R3, and R4 are each independently selected from a methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, or sec-butyl group. Alternatively, the alkyl group may be substituted, and the substituents may be, for example, fluorine, chlorine, bromine, iodine, siloxane, trifluoromethyl, trifluoromethoxy, cyano, or methoxy. Further, the substituents may be, for example, fluorine, trifluoromethyl, or methoxy.

[0027] In the cyclic silicon-oxygen structure represented by Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted unsaturated hydrocarbon group. Alternatively, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C2-C10 unsaturated hydrocarbon group. Further, optionally, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C2-C8, C2-C6, or C2-C4 unsaturated hydrocarbon group. Alternatively, R1, R2, R3, and R4 are each independently selected from a vinyl group, a propenyl group, an isopropenyl group, a butenyl group, an isobutenyl group, a tert-butenyl group, a sec-butenyl group, an ethynyl group, a propynyl group, an isopropynyl group, a butynyl group, an isobutynyl group, a tert-butynyl group, or a sec-butynyl group. Optionally, the unsaturated hydrocarbon group may be substituted, and the substituent may be, for example, fluorine, chlorine, bromine, iodine, methoxy, siloxane, trifluoromethyl, trifluoromethoxy, cyano, methoxy, etc. Further optionally, the substituent may be, for example, fluorine, trifluoromethyl or methoxy.

[0028] In the cyclic silicon-oxygen structure represented by Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted alkoxy group. Alternatively, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C1-C10 alkoxy group. In specific embodiments, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C1-C8, C1-C6, C1-C4, or C1-C2 alkoxy group. Alternatively, the alkoxy group may be substituted, and the substituents may be, for example, fluorine, chlorine, bromine, iodine, a siloxane group, a trifluoromethyl group, a trifluoromethoxy group, a cyano group, or a methoxy group. Furthermore, the substituents may be, for example, fluorine, trifluoromethyl, or a methoxy group.

[0029] In the cyclic silyl structure represented by Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted silanyloxy group. Alternatively, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C1-C10 silanyloxy group. Further, alternatively, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C1-C6 silanyloxy group. Alternatively, the silanyloxy group may be substituted, and the substituents may be, for example, fluorine, chlorine, bromine, iodine, a siloxane group, a trifluoromethyl group, a trifluoromethoxy group, a cyano group, or a methoxy group. Further alternatively, the substituents may be, for example, fluorine, trifluoromethyl, or a methoxy group.

[0030] In the cyclic silyl structure represented by Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted silyl group. Alternatively, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C1-C10 silyl group. Further, alternatively, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C1-C6 silyl group. Alternatively, the silyl group may be substituted, and the substituents may be, for example, fluorine, chlorine, bromine, iodine, a siloxane group, a trifluoromethyl group, a trifluoromethoxy group, a cyano group, or a methoxy group. Further, alternatively, the substituents may be, for example, fluorine, trifluoromethyl, or a methoxy group.

[0031] In the cyclic silyl structure represented by Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted cycloalkyl group. Alternatively, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C3-C10 cycloalkyl group, such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and the like. Optionally, the cycloalkyl group may be substituted, and the substituents may be, for example, fluorine, chlorine, bromine, iodine, a siloxane group, a trifluoromethyl group, a trifluoromethoxy group, a cyano group, a methoxy group, and the like. Further, the substituents may be, for example, fluorine, trifluoromethyl, or methoxy.

[0032] In the cyclic silicon-oxygen structure represented by Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted heterocyclic group. Alternatively, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C3-C10 heterocyclic group. Further, alternatively, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C3-C6 heterocyclic group. Alternatively, the heterocyclic group may be substituted, and the substituents may be, for example, fluorine, chlorine, bromine, iodine, a siloxane group, a trifluoromethyl group, a trifluoromethoxy group, a cyano group, or a methoxy group. Further alternatively, the substituents may be, for example, fluorine, trifluoromethyl, or a methoxy group.

[0033] In the cyclic silicon-oxygen structure represented by Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted aryl group. Alternatively, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C6-C30 aryl group. In specific embodiments, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C6-C25, C6-C20, C6-C15, or C6-C10 aryl group, such as a phenyl group or a naphthyl group. Alternatively, the aryl group may be substituted, and the substituents may be, for example, fluorine, chlorine, bromine, iodine, a siloxane group, a trifluoromethyl group, a trifluoromethoxy group, a cyano group, or a methoxy group. Further, the substituents may be, for example, fluorine, a trifluoromethyl group, or a methoxy group.

[0034] In the cyclic silicon-oxygen structure represented by Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted aryloxy group. Alternatively, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C6-C30 aryloxy group. In specific embodiments, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C6-C25, C6-C20, C6-C15, or C6-C10 aryloxy group, such as a phenoxy group. Alternatively, the aryloxy group may be substituted, and the substituents may be, for example, fluorine, chlorine, bromine, iodine, a siloxane group, a trifluoromethyl group, a trifluoromethoxy group, a cyano group, or a methoxy group. Further, the substituents may be, for example, fluorine, trifluoromethyl, or a methoxy group.

[0035] In the cyclic silicon-oxygen structure represented by Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted heteroaryl group. Alternatively, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C2-C30 heteroaryl group. In specific embodiments, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted C2-C25, C2-C20, C2-C15, or C2-C10 heteroaryl group. Optionally, the heteroaryl group may be substituted, and the substituents may be, for example, fluorine, chlorine, bromine, iodine, siloxane, trifluoromethyl, trifluoromethoxy, cyano, or methoxy. Further, the substituents may be, for example, fluorine, trifluoromethyl, or methoxy.

[0036] In the cyclic silyl structure represented by Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted aldehyde group. Optionally, the aldehyde group may be substituted, and the substituents may be, for example, fluorine, chlorine, bromine, iodine, a siloxane group, a trifluoromethyl group, a trifluoromethoxy group, a cyano group, or a methoxy group. Further, the substituents may be, for example, fluorine, a trifluoromethyl group, or a methoxy group.

[0037] In the cyclic silyl structure represented by Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted keto group. Optionally, the keto group may be substituted, and the substituents may be, for example, fluorine, chlorine, bromine, iodine, a siloxane group, a trifluoromethyl group, a trifluoromethoxy group, a cyano group, a methoxy group, or the like. Further, the substituents may be, for example, fluorine, a trifluoromethyl group, or a methoxy group.

[0038] In the cyclic silyl structure represented by Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from a substituted or unsubstituted ester group. Optionally, the ester group may be substituted, and the substituents may be, for example, fluorine, chlorine, bromine, iodine, a siloxane group, a trifluoromethyl group, a trifluoromethoxy group, a cyano group, or a methoxy group. Further, the substituents may be, for example, fluorine, a trifluoromethyl group, or a methoxy group.

[0039] In some optional embodiments of the present invention, R1, R2, R3, and R4 are each independently selected from hydrogen, halogen, cyano, substituted or unsubstituted linear or branched C1-C10 alkyl, substituted or unsubstituted C2-C10 unsaturated hydrocarbon, substituted or unsubstituted C1-C10 alkoxy, substituted or unsubstituted C1-C10 siloxy, substituted or unsubstituted C1-C10 silyl, substituted or unsubstituted C3-C10 cycloalkyl, substituted or unsubstituted C3-C10 heterocyclyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C6-C30 aryloxy, substituted or unsubstituted C2-C30 heteroaryl, substituted or unsubstituted aldehyde, substituted or unsubstituted ketone, or substituted or unsubstituted ester. Alternatively, the substituted substituent may be, for example, fluorine, chlorine, bromine, iodine, methoxy, siloxane, trifluoromethyl, trifluoromethoxy, cyano, methoxy, etc. Further optionally, the substituent may be, for example, fluorine, trifluoromethyl or methoxy.

[0040] In some optional embodiments of the present invention, R1, R2, R3, and R4 are each independently selected from hydrogen, halogen, cyano, substituted or unsubstituted straight or branched C1-C6 alkyl, substituted or unsubstituted C2-C6 unsaturated hydrocarbon group, substituted or unsubstituted C1-C6 alkoxy, substituted or unsubstituted C1-C6 siloxy, substituted or unsubstituted silyl, substituted or unsubstituted C3-C6 heterocyclic group, substituted or unsubstituted C6-C10 aryl or substituted or unsubstituted C2-C10 heteroaryl. Alternatively, the substituted substituent is selected from fluorine, trifluoromethyl or methoxy. Alternatively, the substituted substituent can be, for example, fluorine, chlorine, bromine, iodine, methoxy, siloxane, trifluoromethyl, trifluoromethoxy, cyano, methoxy, etc., and further optionally, the substituent can be, for example, fluorine, trifluoromethyl or methoxy.

[0041] In some optional embodiments of the present invention, R1, R2, R3, and R4 are each independently selected from hydrogen, fluorine, cyano, methyl, ethyl, substituted ethyl, trifluoromethyl, monofluoromethyl, vinyl, propenyl, phenyl, and substituted phenyl, wherein the substituted substituent is selected from fluorine, trifluoromethyl, or methoxy.

[0042] In the non-aqueous electrolyte provided by the present invention, the cyclic silicon-oxygen structure represented by Formula I is selected from any one or more of the following structures:

[0043]

[0044] In the non-aqueous electrolyte provided by the present invention, the mass proportion of the cyclic silicon oxide structure represented by Formula I in the non-aqueous electrolyte is 1wt% to 2wt%. In some embodiments, the mass proportion of the cyclic silicon oxide structure represented by Formula I in the non-aqueous electrolyte can also be 1wt% to 1.5wt%, 1.5wt% to 2wt%, etc. If the amount of the cyclic silicon oxide structure represented by Formula I added is too small (less than 1wt%), the performance cannot be effectively exerted and the improvement of the lithium-ion battery is not obvious; if the amount added is too large (greater than 2wt%), the viscosity of the electrolyte and the thickness of the SEI film will increase, which is not conducive to ion transport and deteriorates the rate performance and low-temperature performance of the battery.

[0045] In the non-aqueous electrolyte provided by the present invention, the mass proportion of the 2-trifluoromethyl-1,3-propene sultone (TFMPS) in the non-aqueous electrolyte is 1wt% to 2wt%. In some embodiments, the mass proportion of the 2-trifluoromethyl-1,3-propene sultone in the non-aqueous electrolyte can also be 1wt% to 1.5wt%, 1.5wt% to 2wt%, etc. If the addition amount of 2-trifluoromethyl-1,3-propene sultone (TFMPS) is too small (less than 1wt%), the performance cannot be effectively exerted and the improvement of the lithium-ion battery is not obvious; if the addition amount is too large (greater than 2wt%), the internal resistance of the battery will increase and the cycle performance of the battery will deteriorate.

[0046] In the non-aqueous electrolyte provided by the present invention, the mass proportion of the vinylene carbonate (VC) in the non-aqueous electrolyte is 1wt% to 2wt%. In some embodiments, the mass proportion of the vinylene carbonate in the non-aqueous electrolyte can also be 1wt% to 1.5wt%, 1.5wt% to 2wt%, etc. If the amount of vinylene carbonate (VC) added is too little (less than 1wt%), a complete and effective organic interface film cannot be formed, and the improvement of the lithium-ion battery is not obvious; if the amount added is too much (greater than 2wt%), the internal resistance of the battery will increase, and vinylene carbonate (VC) has poor high-temperature performance. Adding too much will cause serious gas production in the battery cell at high temperatures.

[0047] In the non-aqueous electrolyte provided by the present invention, the lithium salt is selected from lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium hexafluorosilicate (LiSiF6), lithium aluminum tetrachloride (LiAlCl4), lithium bis(oxalatoborate) (LiBOB), lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI), lithium trifluoromethanesulfonate (LiOTF), and lithium bis(trifluoromethanesulfonic acid)imide (LiTFSI). Preferably, the lithium salt is selected from lithium hexafluorophosphate (LiPF6) and / or lithium bis(fluorosulfonyl)imide (LiFSI).

[0048] In the non-aqueous electrolyte provided by the present invention, the concentration of the lithium salt in the non-aqueous electrolyte is 0.5 to 2 mol / L. In some embodiments, the concentration of the lithium salt in the non-aqueous electrolyte can also be 0.5 to 1 mol / L, 1 to 1.2 mol / L, 1.2 to 2 mol / L, 1 to 1.5 mol / L or 1.5 to 2 mol / L. The lithium salt is Li in the electrolyte. + Lithium salt is the main source of energy, and has a significant impact on the energy density, power density, wide electrochemical window, cycle life, and safety performance of lithium batteries. Too much lithium salt will increase the viscosity of the electrolyte, while too little will not provide the appropriate amount of lithium ions, both of which will cause a decrease in ionic conductivity.

[0049] In the non-aqueous electrolyte provided by the present invention, the solvent is selected from a combination of one or more of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (GBL), methyl acetate (MA), ethyl acetate (EA), ethyl propionate (EP), propyl propionate (PP), and methyl butyrate (MB). Preferably, the solvent is selected from ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). The volume ratio of the solvent selected from ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) can be, for example, (2-4): (4-6): (1-3). Further preferably, the volume ratio of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) is 3:5:2.

[0050] In the non-aqueous electrolyte provided by the present invention, the mass proportion of the solvent in the non-aqueous electrolyte is 68% to 75%. In some embodiments, the mass proportion of the solvent in the non-aqueous electrolyte can also be 68% to 72%, 72% to 75%, etc. The electrolyte solvent is mainly composed of a cyclic carbonate solvent and a chain carbonate solvent mixed in a certain proportion. The cyclic carbonate solvent has a high dielectric constant, which is conducive to the dissociation of lithium ions, but a large amount will increase the viscosity of the electrolyte and reduce the ionic conductivity. The chain carbonate solvent has a low viscosity and better electrochemical stability, but a large amount will lead to a deterioration in the dissociation of lithium ions.

[0051] Lithium-ion battery

[0052] A second aspect of the present invention provides a lithium-ion battery, which further includes a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte. The non-aqueous electrolyte is selected from the non-aqueous electrolyte of the first aspect of the present invention.

[0053] 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 can be a metal foil or a composite current collector. For example, aluminum foil can be used as the metal foil. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The positive electrode active material layer includes a positive electrode active material and may further include a conductive agent and a binder. The positive electrode active material can be selected from one or more of lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium iron manganese phosphate, lithium nickel cobalt aluminum oxide, and lithium iron phosphate. Lithium nickel cobalt manganese oxide is preferred. Those skilled in the art can select conductive agents and binders suitable for lithium-ion batteries. The conductive agent can 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.

[0054] In some embodiments, the positive electrode can be prepared by the following method: 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 the positive electrode is obtained after drying, cold pressing and other processes.

[0055] 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 can be a metal foil or a composite current collector. For example, copper foil can be used as the metal foil. The composite current collector can include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. The negative electrode active material layer includes a negative electrode active material and may further include a plasticizer, a conductive agent, and a binder. The negative electrode active material can be selected from one or more of silicon carbon, silicon oxide, natural graphite, artificial graphite, lithium titanate, amorphous carbon, and lithium metal. Preferably, the negative electrode active material can be selected from artificial graphite. Those skilled in the art can select plasticizers, conductive agents, and binders suitable for lithium-ion batteries. The conductive agent can be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The binder can 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).

[0056] In some embodiments, the negative electrode can be prepared by the following method: 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.

[0057] The lithium-ion battery provided in the second aspect of the present invention can be prepared using methods known in the art. For example, the positive electrode, separator, and negative electrode are stacked in order, with the separator positioned between the positive and negative electrodes to provide isolation. The stacking process then proceeds to obtain a bare cell. The bare cell is then placed in an outer packaging casing, dried, and then injected with an electrolyte. The lithium-ion battery is then vacuum packaged, allowed to stand, formed, and shaped.

[0058]

Battery Module

[0059] A third aspect of the present invention provides a battery module comprising any one or more of the 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.

[0060]

Battery Pack

[0061] A fourth aspect of the present invention provides a battery pack comprising any one or more of the battery modules described in the third aspect of the present invention. That is, the battery pack comprises any one or more of the lithium-ion batteries described in the second aspect of the present invention.

[0062] The number of battery modules in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0063]

Electrical devices

[0064] A fifth aspect of the present invention provides an electrical device comprising any one or more of the 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 electrical device. Preferably, the electrical device can be, but is not limited to, a mobile device (e.g., a mobile phone, a laptop computer, etc.), an electric vehicle (e.g., 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, a satellite, an energy storage system, etc.

[0065] The beneficial effects of the present invention are further illustrated below with reference to the examples.

[0066] In order to make the invention objectives, technical solutions and beneficial technical effects of the present invention clearer, the present invention is further described in detail below with reference to the examples. However, it should be understood that the examples of the present invention are only for the purpose of explaining the present invention and are not intended to limit the present invention, and the examples of the present invention are not limited to the examples given in the specification. In the examples, where no specific experimental conditions or operating conditions are specified, the products were prepared under conventional conditions or under the conditions recommended by the material supplier.

[0067] In addition, it should be understood that the one or more method steps mentioned in the present invention do not exclude the presence 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 presence of other devices / devices before or after the combination device / device, or the insertion of other devices / devices between two explicitly mentioned devices / devices, unless otherwise specified. Moreover, unless otherwise specified, the numbering of each method step is merely a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of the present invention. Changes or adjustments to their relative relationships, without substantially changing the technical content, should also be considered within the scope of the present invention.

[0068] In the following examples, unless otherwise specified, various raw materials of the present invention can be purchased commercially or prepared according to conventional methods in the art.

[0069] In the present invention, the cyclic silicon-oxygen structure compound and raw materials were purchased from Chemieliva Pharmaceutical Co., Ltd.

[0070] The positive electrode material of the lithium ion battery used in the embodiment and comparative example of the present invention is LiNi 0.5 Co 0.2 Mn 0.3 O2, artificial graphite is used for the negative electrode, and the electrolyte injection volume of each battery is 4g.

[0071] The preparation process of the lithium ion batteries of Examples 1 to 10 and Comparative Examples 1 to 10 is as follows:

[0072] The electrolyte was prepared in a dry room (dry room dew point below -40°C). Ethyl methyl carbonate (EMC), ethylene carbonate (EC), and diethyl carbonate (DEC) were mixed in a volume ratio of 5:3:2 as an organic solvent, for a total of 100 mL. LiPF6 with a lithium salt molar concentration of 1 mol / L was added to the organic solvent, followed by a certain amount of additives (see Table 1 for the additives and amounts for each example and comparative example). After mixing evenly, the electrolytes of Examples 1 to 10 and Comparative Examples 1 to 10 were obtained. The prepared electrolyte was injected into a soft-pack battery. After standing, formation, and volume separation, a lithium-ion battery was obtained.

[0073] Table 1: Additives used in Examples 1 to 10 and Comparative Examples 1 to 10 and their contents

[0074]

[0075]

[0076] The following experiments were conducted on the batteries obtained in Examples 1 to 10 and Comparative Examples 1 to 10. The test results are shown in Table 2.

[0077] (1) High-temperature cycling performance test: After formation and capacity separation, the batteries obtained in Examples 1-10 and Comparative Examples 1-10 were charged at 45°C at a constant current and constant voltage of 1C to a voltage of 4.4V and a current of 0.05C, left for 10 minutes, and discharged at a constant current of 1C to 2.7V. The above is considered one charge-discharge cycle. After formation and capacity separation, the obtained batteries were subjected to 1000 charge-discharge cycles at 45°C.

[0078] (2) High-temperature storage performance test: After formation and capacity separation, the batteries obtained in Examples 1 to 10 and Comparative Examples 1 to 10 were charged at 1C constant current and constant voltage at 25°C to a voltage of 4.4V and a 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 30 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 4.4V and a current of 0.05C, and then discharged at 1C constant current to 2.7V, and the 1C discharge capacity Q2 was recorded. The capacity retention rate, recovery rate and battery expansion rate of the batteries after storage were calculated;

[0079] The calculation formulas are as follows:

[0080] Capacity retention rate = Q1 / Q×100%; capacity recovery rate = Q2 / Q×100%; battery expansion rate = (H1-H) / H×100%.

[0081] Table 2

[0082]

[0083]

[0084] As can be seen from Table 2, compared with the lithium-ion battery of the comparative example, the lithium-ion battery of the embodiment of the present invention, in which the addition amount of cyclic siloxane additives in the electrolyte is between 1wt% and 2wt% and 1wt% to 2wt% TFMPS and 1wt% to 2wt% VC are added simultaneously, exhibits better high-temperature cycling performance and high-temperature storage performance. Replacing any of the above additives with 1,3-propane sultone (PS), vinyl sulfate (DTD), or fluoroethylene carbonate (FEC) does not achieve the desired effect. This is mainly due to the fact that cyclic siloxane additives can not only effectively remove harmful acidic substances in the electrolyte, but also improve the oxidation resistance of the electrolyte. At the same time, the three-dimensional network structure formed can also provide effective interface protection. TFMPS and VC can form a stable double-layer SEI film with a lower layer of high-conductivity (sulfite) and LiF, and an upper layer of highly elastic polymer, which ensures both high ion transmission rate and good toughness, and will not easily break and decompose during long-term cycling.

[0085] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form or substance. 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. These improvements and supplements should also be regarded as the scope of protection of the present invention. Any equivalent changes, modifications and evolutions made by technicians familiar with this profession without departing from the spirit and scope of the present invention by using the technical content disclosed above are all equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications and evolutions 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 non-aqueous electrolyte includes a lithium salt, a solvent and a functional additive, wherein the functional additive includes a cyclic silicon-oxygen structure represented by formula I, 2-trifluoromethyl-1,3-propene sultone and vinylene carbonate; In Formula I, R1, R2, R3, and R4 are each independently selected from hydrogen, halogen, cyano, substituted or unsubstituted linear or branched alkyl, substituted or unsubstituted unsaturated hydrocarbon, substituted or unsubstituted alkoxy, substituted or unsubstituted siloxy, substituted or unsubstituted silanyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocyclic, substituted or unsubstituted aryl, substituted or unsubstituted aryloxy, substituted or unsubstituted heteroaryl, substituted or unsubstituted aldehyde, substituted or unsubstituted keto, or substituted or unsubstituted ester.

2. The non-aqueous electrolyte according to claim 1, characterized in that R1, R2, R3, and R4 are each independently selected from hydrogen, halogen, cyano, substituted or unsubstituted linear or branched C1-C10 alkyl, substituted or unsubstituted C2-C10 unsaturated hydrocarbon, substituted or unsubstituted C1-C10 alkoxy, substituted or unsubstituted C1-C10 siloxy, substituted or unsubstituted C1-C10 silyl, substituted or unsubstituted C3-C10 cycloalkyl, substituted or unsubstituted C3-C10 heterocyclyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C6-C30 aryloxy, substituted or unsubstituted C2-C30 heteroaryl, substituted or unsubstituted aldehyde, substituted or unsubstituted ketone, or substituted or unsubstituted ester.

3. The non-aqueous electrolyte according to claim 1, characterized in that R1, R2, R3, and R4 are each independently selected from hydrogen, halogen, cyano, substituted or unsubstituted linear or branched C1-C6 alkyl, substituted or unsubstituted C2-C6 unsaturated hydrocarbon, substituted or unsubstituted C1-C6 alkoxy, substituted or unsubstituted C1-C6 siloxy, substituted or unsubstituted silyl, substituted or unsubstituted C3-C6 heterocyclyl, substituted or unsubstituted C6-C10 aryl, or substituted or unsubstituted C2-C10 heteroaryl.

4. The non-aqueous electrolyte according to claim 1, wherein R1, R2, R3, and R4 are each independently selected from hydrogen, fluorine, cyano, methyl, ethyl, substituted ethyl, trifluoromethyl, monofluoromethyl, vinyl, propenyl, phenyl, and substituted phenyl, wherein the substituted substituent is selected from fluorine, trifluoromethyl, or methoxy.

5. The non-aqueous electrolyte according to any one of claims 1 to 4, characterized in that The cyclic silicon-oxygen structure represented by Formula I is selected from any one or more of the following structures:

6. The non-aqueous electrolyte according to claim 1, characterized in that Also includes any one or more of the following conditions: A1) the mass percentage of the cyclic silicon-oxygen structure represented by formula I in the non-aqueous electrolyte is 1 wt% to 2 wt%; A2) the mass proportion of the 2-trifluoromethyl-1,3-propene sultone in the non-aqueous electrolyte is 1 wt% to 2 wt%; A3) the mass proportion of the vinylene carbonate in the non-aqueous electrolyte is 1 wt% to 2 wt%; A4) the lithium salt is selected from the group consisting of one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, 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; A5) the concentration of the lithium salt in the non-aqueous electrolyte is 0.5 to 2 mol / L; A6) the solvent is selected from one or more combinations of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, γ-butyrolactone, methyl acetate, ethyl acetate, ethyl propionate, propyl propionate, and methyl butyrate; A7) The mass proportion of the solvent in the non-aqueous electrolyte is 68 wt% to 75 wt%.

7. The non-aqueous electrolyte according to claim 6, characterized in that Also includes any one or more of the following conditions: A41) the lithium salt is selected from lithium hexafluorophosphate and / or lithium bis(fluorosulfonyl)imide; A61) The solvent is selected from ethylene carbonate, ethyl methyl carbonate and diethyl carbonate.

8. 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 7.

9. The lithium-ion battery according to claim 8, characterized in that The negative electrode comprises a negative electrode active material, wherein the negative electrode active material is selected from a combination of one or more of silicon carbon, silicon oxide, 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 manganese iron phosphate, lithium nickel cobalt aluminum oxide and lithium iron phosphate.

10. A battery module, characterized in that: Comprising the lithium ion battery according to claim 8 or 9.

11. A battery pack, characterized in that: The battery module according to claim 10 is included.

12. An electrical device, characterized in that: The lithium-ion battery according to claim 8 or 9 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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