Non-aqueous electrolyte and secondary battery comprising the same

Abstract

This invention discloses a non-aqueous electrolyte and a secondary battery comprising the non-aqueous electrolyte. The non-aqueous electrolyte of this invention comprises a lithium salt, a non-aqueous organic solvent, and an additive. The additive includes a first additive having the structure shown in Formula I, wherein M... + Selected from heterocyclic ononium cations containing tertiary amine nitrogen, aliphatic tertiary amine ononium cations, or N,N-dialkyl-substituted amide ononium cations, Q ‑ It contains fluorine-containing anionic groups. The non-aqueous electrolyte of this invention, due to the inclusion of ionic compounds with special structures, can effectively improve the electrochemical performance of secondary batteries, especially high-rate cycling performance and low-temperature discharge performance.

Description

Technical Field

[0001] This invention relates to the field of secondary battery technology, and in particular to a non-aqueous electrolyte and a secondary battery containing the non-aqueous electrolyte. Background Technology

[0002] Secondary batteries, taking lithium-ion batteries as an example, are a type of recyclable energy storage technology. Compared with other commonly used battery products, lithium-ion batteries have advantages such as high capacity, long lifespan, and environmental friendliness, thus gaining favor among many researchers. However, with the upgrading of energy structures and the continuous expansion of the global market, high-safety, high-rate, and low-temperature resistant lithium-ion batteries have become one of the main research directions for the future.

[0003] Ionic compounds refer to a class of molten salts composed of organic cations and inorganic / organic anions that are liquid near room temperature (also known as ionic compounds). Among the many additives studied, ionic compounds have many advantages such as low vapor pressure, high temperature resistance, non-flammability, and high thermal stability. They are often used as beneficial components in safe electrolyte systems. In addition, the designability of ionic compounds can be used to specifically improve the electrochemical performance of batteries. Therefore, ionic compounds are a potential multifunctional additive.

[0004] In existing technologies, Swanderska-Mocek et al. [DIO:10.1016 / j.electacta.2014.03.185] dissolved solid lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in a vinyl-containing 1-ethyl-3-vinylimidazolium (EVImTFSI) ionic compound solvent to form a novel electrolyte system for lithium-ion batteries. Electrochemical testing results showed that Li... +Pyrrole ions can be reversibly and stably inserted and extracted into LiFePO4 and graphite materials, exhibiting excellent battery cycle performance. Kim HT et al. [[DIO:10.1016 / j.electacta.2017.04.078] designed and synthesized several novel pyrrole ion compounds with certain specific functional groups (i.e., planar C¼N double bonds, CO ether bonds, and stable CH bonds), which were then combined with LiTFSI to form a novel electrolyte system as an alternative to organic carbonate electrolyte systems to improve their electrochemical performance. Experimental results showed that pyrrole ion compounds can significantly improve the electrochemical performance of batteries. Dong et al. [[DIO:10.1071 / CH15154] reported an ester-functionalized ionic compound [MMEPyr][TFSI] as an effective electrolyte additive for Li / LiMn2O4 batteries, exhibiting excellent cycling and rate performance. After 100 charge-discharge cycles, it retained 94% of its initial discharge capacity and 90% of its initial capacity at a current density of 2.5C. However, the aforementioned ionic compound has limited effect on improving the low-temperature cycling performance and room-temperature cycling performance at higher rates of secondary batteries.

[0005] Therefore, there is an urgent need for a non-aqueous electrolyte and a secondary battery containing the non-aqueous electrolyte. The shortcomings of the existing technology can be addressed by developing new ionic compounds as additives for the non-aqueous electrolyte. Summary of the Invention

[0006] The purpose of this invention is to provide a non-aqueous electrolyte and a secondary battery containing the non-aqueous electrolyte. The non-aqueous electrolyte contains ionic compounds with special structures, which can effectively improve the electrochemical performance of the secondary battery, especially its high-rate cycling performance and low-temperature discharge performance.

[0007] To achieve the above objectives, the present invention provides a non-aqueous electrolyte comprising a lithium salt, a non-aqueous organic solvent, and an additive, wherein the additive comprises a first additive having the structure shown in Formula I.

[0008] Formula I Among them, M + Selected from heterocyclic ononium cations containing tertiary amine nitrogen, aliphatic tertiary amine ononium cations, or N,N-dialkyl-substituted amide ononium cations, Q - It contains fluorine anionic groups.

[0009] Compared with existing technologies, the additive of the present invention includes a first additive having the structure shown in Formula I. The core function of this fluorosulfonium cation structure is to enhance electrode interface protection, inhibit electrolyte degradation, and broaden the electrochemical window. Compared with ordinary onium salt additives, the introduction of fluorosulfonyl groups further improves interfacial reactivity and stability. On the one hand, the compounds of the present invention help form a dense, highly ionicly conductive, and redox-resistant interfacial film on the positive and negative electrode surfaces, significantly reducing side reactions between the electrode and the electrolyte and extending battery cycle life. Because fluorosulfonyl groups have strong electron-withdrawing properties and high reactivity, they preferentially undergo redox reactions on the electrode surface compared to solvent molecules. The decomposition products (compounds containing F, O, and S) combine with nitrogen-containing species generated from cation decomposition to form a composite interfacial membrane (CEI / SEI membrane) that possesses both hydrophobicity and high adhesion. The conjugated structure of heterocyclic cations (pyridinium, N-methylpyrrolonnium, thiazonnium) enhances the membrane's rigidity and stability, while aliphatic cations (triethylaminennium) and N,N-dialkyl-substituted amide-nnium (such as N,N-dimethylformamidennium) improve the membrane's flexibility, preventing rupture during cycling. Fluoride-containing anions (such as difluorosulfonylimide and difluorophosphate) participate in the membrane's construction, introducing PF and SF bonds, thus improving the membrane's ionic conductivity and hydrolysis resistance. Furthermore, the compounds of this invention help inhibit electrolyte hydrolysis and degradation, reduce HF generation in the electrolyte, inhibit solvent oxidative decomposition and gas generation, and improve the electrolyte's storage stability and high-temperature resistance. Because the strong electron-withdrawing property of the fluorosulfonyl group can reduce the basicity of the nitrogen atom at the center of the cation, it reduces the binding of the nitrogen atom with trace amounts of water in the electrolyte. Simultaneously, it directly captures water and HF (through hydrogen bonding or substitution reactions between -SO₂F and HF), blocking fluoride-containing anions (such as PF₆). - The hydrolysis chain reaction of the electrolyte. Therefore, the non-aqueous electrolyte of the present invention contains ionic compounds with special structures, which can effectively improve the electrochemical performance of secondary batteries, especially high-rate cycling performance and low-temperature discharge performance.

[0010] Furthermore, M + Selected from pyridinium cations, N-methylpyrrolonnium cations, thiazonnium cations, triethylaminennium cations, triallylaminennium cations, N,N-dimethylformamidennium cations, N,N-dimethylacetamidennium cations, or N,N-dimethylacrylamidennium cations, Q - It is selected from hexafluorophosphate, difluorophosphate, tetrafluoroborate, difluorosulfonylimide or ditrifluoromethylsulfonylimide.

[0011] Furthermore, the first additive of the present invention comprises at least one of compounds 1 to 6.

[0012] Compound 1, Compound 2, Compound 3

[0013] Compound 4, Compound 5, Compound 6.

[0014] Furthermore, the mass percentage of the first additive in the non-aqueous electrolyte is 0.1% to 5%. Specifically, the mass percentage of the first additive in the non-aqueous electrolyte may be, but is not limited to, 0.1%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%.

[0015] Furthermore, the additive also includes a second additive, which is lithium difluorobis(oxalato) phosphate (LiDFBP), and the mass percentage of lithium difluorobis(oxalato) phosphate in the non-aqueous electrolyte is 0.1% to 4.5%. Specifically, the mass percentage of lithium difluorobis(oxalato) phosphate in the non-aqueous electrolyte can be, but is not limited to, 0.1%, 0.2%, 0.5%, 0.8%, 1.0%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, and 4.5%.

[0016] Furthermore, the additives also include a third additive, which is fluoroethylene carbonate (FEC), and the mass percentage of fluoroethylene carbonate in the non-aqueous electrolyte is 0.1% to 5.5%. Specifically, the mass percentage of fluoroethylene carbonate in the non-aqueous electrolyte may be, but is not limited to, 0.1% to 4.5%. Specifically, the mass percentage of lithium difluorobis(oxalato)phosphate in the non-aqueous electrolyte may be, but is not limited to, 0.1%, 0.2%, 0.5%, 0.8%, 1.0%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5.0%, and 5.5%.

[0017] Furthermore, the lithium salt includes at least one of lithium dioxolane borate (LiBOB), lithium hexafluorophosphate (LiPF6), lithium difluorooxolane borate (LiDFOB), lithium tetrafluoroborate (LiBF4), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium methanesulfonate (LiCH3SO3), lithium trifluoromethanesulfonate (LiCF3SO3), lithium fluorosulfonate, lithium perchlorate (LiClO4), and lithium difluorophosphate (LiPO2F2).

[0018] Further, the non-aqueous organic solvent includes at least one selected from carbonates, carboxylic acid esters, and ethers. Preferably, the non-aqueous organic solvent of the present invention is selected from carbonates. Furthermore, non-aqueous organic solvents include propylene carbonate (PCA), butyl carbonate (BC), amyl carbonate, vinyl carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), methyl n-propyl carbonate, ethyl n-propyl carbonate, propylene carbonate (PC), ethylene carbonate (EC), γ-butyrolactone (GBL), γ-valerolactone (GVL), δ-valerolactone (DVL), methyl acetate (MA), ethyl acetate (EA), ethyl propionate, and butyl acetate (BAC). At least one of the following: propyl propionate (PP), butyl propionate (PRB), 2-trifluoromethyltetrahydrofuran (2-CF3-THF), dimethoxymethane (DMM), diethoxymethane (DEM), 1,3-dioxolane (DOL), 1,4-dioxane (DX), ethoxymethoxymethane (DCE), crown ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-CH3-THF), ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether (EDB), and diethylene glycol dimethyl ether (DEGME).

[0019] Another aspect of the present invention provides a secondary battery comprising the aforementioned non-aqueous electrolyte.

[0020] Furthermore, the secondary battery of the present invention also includes a positive electrode and a negative electrode. The active material of the positive electrode includes lithium iron phosphate, and the active material of the negative electrode includes artificial graphite. Detailed Implementation

[0021] To better illustrate the purpose, technical solution, and beneficial effects of this invention, the invention will be further described below with reference to specific embodiments. It should be noted that the methods described below are further explanations of this invention and should not be construed as limiting it.

[0022] The preparation methods of compounds 1 to 6 involved in the embodiments of the present invention include: stirring and mixing the nitrogen-containing compounds in a carbonate solvent, then introducing sulfuryl fluoride at 0 to 10°C and stirring until the system no longer absorbs sulfuryl fluoride; heating the system to 25 to 45°C, then adding lithium salt solution dropwise and maintaining the temperature for reaction, while continuously introducing sulfuryl fluoride during the reaction; after the reaction is completed, filtering the reaction solution, concentrating and crystallizing the filtrate to obtain fluorosulfonamide ionic compounds, wherein the lithium salt solution is obtained by dissolving a fluorinated anionic lithium salt in a carbonate solvent, and the molar ratio of the fluorinated anionic lithium salt to the nitrogen-containing compound is 1:0.8 to 1.2.

[0023] Specifically, taking compound 1 (fluorosulfonylpyridine hexafluorophosphate onium salt) as an example, its preparation method includes the following steps: dissolving 48.0g of lithium hexafluorophosphate in 300g of anhydrous dimethyl carbonate to obtain a lithium hexafluorophosphate solution for later use; adding 25g of pyridine and 250g of anhydrous dimethyl carbonate to a reaction vessel, stirring evenly, and controlling the temperature at 5℃, then introducing sulfuryl fluoride gas, stirring the reaction until the reaction is complete (weighing the sulfuryl fluoride cylinder; the reaction is complete when the weight no longer decreases); then raising the temperature to 35℃, and... A lithium hexafluorophosphate solution was added dropwise to a reaction vessel, and the mixture was kept at a constant temperature and stirred for 6 hours. During the reaction, sulfuryl fluoride gas was continuously introduced, and insoluble matter was precipitated. After the reaction was completed, the insoluble matter was filtered out, and the filtrate was evaporated under reduced pressure at 45°C to obtain a concentrated solution with a solid content of more than 40% (calculated based on the theoretical product). The solution was cooled to -5°C, and then 500g of n-hexane was slowly added dropwise to the concentrated solution, precipitating a white solid. After stirring for 2 hours, the solution was filtered, the filter cake was washed with n-hexane, and dried to obtain 52.3g of compound 1, with a yield of 53.9%. 1 ¹H NMR (400MHz, deuterated DMSO, ppm): 8.28 (t, J=7.0Hz, 2H), 8.38 (m, 2H), 9.49 (m, J=6.2Hz, 1H); 19 F-NMR (100MHz, deuterated DMSO, ppm): δ -77.1, -143.2. The reaction equation is shown in Reaction Equation 1 below:

[0024] Reaction 1 Compounds 2-6 were prepared using the same method as compound 1. Specifically, in the preparation of compound 2, the fluorinated anionic lithium salt was replaced with lithium tetrafluoroborate; in the preparation of compound 3, the nitrogen-containing compound was replaced with N-methylpyrrole; in the preparation of compound 4, the nitrogen-containing compound was replaced with N,N-dimethylacrylamide; in the preparation of compound 5, the nitrogen-containing compound was replaced with N,N-dimethylacrylamide and the fluorinated anionic lithium salt was replaced with lithium tetrafluoroborate; and in the preparation of compound 6, the nitrogen-containing compound was replaced with triethylamine and the fluorinated anionic lithium salt was replaced with lithium tetrafluoroborate. More specifically, the reaction formulas for compounds 2-6 are shown in reactions two through six below:

[0025] Reaction 2

[0026] Reaction 3

[0027] Reaction 4

[0028] Reaction 5

[0029] Reaction Formula 6 For any other items in the examples and comparative examples where specific conditions are not specified, they can be carried out under conventional conditions or conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained commercially.

[0030] Example 1 (1) Preparation of electrolyte In a nitrogen-filled glove box (O2 < 1 ppm, H2O < 1 ppm), ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed thoroughly at a weight ratio of EC:DMC:EMC = 3:3:4 to obtain 87.5 g of non-aqueous organic solvent. Then, 0.5 g of the first additive compound 1 was added to obtain a mixed solution. The mixed solution was sealed and packaged, and frozen in a freezer (-4°C) for 2 hours. After removal, 12 g of lithium hexafluorophosphate was slowly added to the mixed solution in a nitrogen-filled glove box (O2 < 1 ppm, H2O < 1 ppm). After thorough mixing, the electrolyte was prepared.

[0031] (2) Preparation of positive electrode sheet Lithium iron phosphate (LiFePO4), polyvinylidene fluoride (PVDF) binder, and acetylene black conductive agent were mixed evenly at a mass ratio of 92:3:5 to prepare a lithium battery positive electrode slurry. The mixed slurry was coated on both sides of aluminum foil, dried, and rolled to obtain the positive electrode sheet.

[0032] (3) Preparation of negative electrode sheet Artificial graphite was mixed with conductive agent SuperP, thickener sodium carboxymethyl cellulose (CMC), and binder styrene-butadiene rubber latex (SBR) in a mass ratio of 94:2.5:1.5:2 to form a slurry, which was then thoroughly mixed. The slurry was coated on both sides of a copper foil, dried, and rolled to obtain the negative electrode sheet.

[0033] (4) Preparation of lithium batteries The positive electrode, separator, and negative electrode are stacked to form a square cell, packaged in aluminum-plastic film, and filled with the electrolyte prepared above. After formation and capacity testing, a lithium battery with a capacity of 1200mAh is produced. The battery is formed according to the following steps: 0.02C constant current charging at 45℃ (limited to 240min), followed by 0.15C constant current charging (limited to 3.65V, limited to 120min).

[0034] The composition and content of the electrolytes in Examples 1-15 and Comparative Examples 1-5 are shown in Table 1. The preparation processes of the lithium-ion battery electrolytes, positive electrode sheets, negative electrode sheets, and lithium-ion batteries in Examples 2-15 and Comparative Examples 1-5 are the same as those in Example 1.

[0035] Table 1. Non-aqueous electrolyte formulations for examples and comparative examples.

[0036] In Table 1, DTD refers to vinyl sulfate. The structural formulas of compounds A and B are shown below.

[0037] Compound A

[0038] Compound B The lithium-ion batteries prepared in Examples 1-15 and Comparative Examples 1-5 were subjected to high-rate cycle performance tests and low-temperature discharge performance tests. The test conditions are as follows, and the test results are shown in Table 2.

[0039] (1) High-rate cycling performance test Under normal temperature (25℃) conditions, the lithium-ion battery was subjected to one 3.0C / 3.0C charge and discharge cycle (the battery discharge capacity was recorded as C0), with an upper limit voltage of 3.65V; then, it was subjected to 500 cycles of 3.0C / 3.0C charge and discharge, and the capacity retention rate was calculated.

[0040] Capacity retention rate = (Battery capacity after 500 cycles C1 / Initial battery capacity C0) × 100% (2) Low-temperature discharge test Under normal temperature (25℃) conditions, a lithium-ion battery is subjected to a single 0.5C / 0.5C charge-discharge cycle (battery cutoff voltage 3.0V, discharge capacity C0), with an upper limit voltage of 4.1V (cutoff current 0.05C). The battery is then fully charged to 4.1V at 0.5C (cutoff current 0.05C) at room temperature (25℃), and then transferred to -20℃ for 4 hours. It is then discharged at 0.5C to 3.0V, with a discharge capacity of C1. The capacity retention rate is calculated.

[0041] Capacity retention rate = (C1 / C0) × 100% Table 2 Performance test results of the examples and comparative examples

[0042] As can be seen from the test results in Table 1, compared with Comparative Examples 1 to 5, Examples 1 to 15 of the present invention have superior high-rate cycle retention rate and low-temperature cycle capacity retention rate.

[0043] As shown in Examples 1-6 and Examples 7-12, adding a second and / or third additive to the first additive can further improve the performance of the secondary battery. This may be because when the first additive is combined with lithium difluorobis(oxalato) phosphate (LiDFBOP), the two can synergistically generate a composite SEI / CEI film containing boron, sulfur, and nitrogen with high LiF content at the positive and negative electrode interfaces. This significantly improves the mechanical strength and chemical stability of the film, effectively inhibits electrolyte oxidation and decomposition and positive electrode transition metal dissolution, and further reduces interfacial impedance, resulting in a significant improvement in capacity retention under high-rate cycling. Simultaneously, they can jointly capture HF in the electrolyte, reducing electrode corrosion and extending battery cycle life. When the first additive is combined with fluoroethylene carbonate (FEC), FEC supplements the SEI film with flexible polycarbonate components, buffering the volume expansion caused by high-rate charging and discharging, preventing repeated SEI rupture. At the same time, the two synergistically reduce the low-temperature impedance of the SEI, significantly improving the LiF content. + The improved transport efficiency at low temperatures significantly enhances the low-temperature cycling capacity retention rate and prevents solvent co-intercalation into the negative electrode, protecting the electrode structure and reducing irreversible capacity loss.

[0044] When the first, second, and third additives are used in combination, the effect on improving the capacity retention rate at high rates and low temperatures is the best. This is likely because the combination of the first additive, lithium difluorobis(oxalato) phosphate, and fluoroethylene carbonate creates a triple synergistic effect of "film formation-reinforcement-interface stabilization." The first additive provides a high-ionic-conductivity sulfur-nitrogen / LiF film-forming framework, FEC supplements the flexible polycarbonate component to buffer volumetric stress, and LiDFBOP provides the boron-containing component to enhance the chemical stability and mechanical properties of the film. The strength ultimately forms a dense, highly conductive, highly tough, and highly stable composite interface film, which simultaneously solves the three core pain points of high-rate cycling, low-temperature cycling, and long-cycle cycling. It maximizes the capacity retention rate during high-rate cycling and low-temperature cycling, and can also completely suppress the generation of by-products such as HF, block the direct contact between the electrolyte and the electrode, reduce capacity decay from the source, and adapt to extreme conditions such as fast charging, low temperature, and high voltage. Moreover, the reduction potentials of the three components are matched, with no antagonistic competition. The film quality and overall performance are far superior to the two-agent combination, making it the optimal solution for improving the performance of secondary batteries.

[0045] As can be seen from the comparison of Example 9 with Comparative Examples 2 and 3, when Compound 1 is replaced with Compound A, the performance decreases. This may be because Compound A is N-butyl-N-methylpiperidinium tetrafluoroborate, whose structure completely lacks the core functional group -N of the original first additive. + -SO2F (fluorosulfonyl) retains only the skeleton of the alkyl-substituted piperidinium quaternary ammonium salt, thus completely losing the core film-forming ability of the original additive: it cannot preferentially reduce and decompose at the positive and negative electrode interfaces, cannot generate high ionic conductivity SEI / CEI films containing LiF or sulfur / nitrogen organic lithium salts, and cannot reduce interfacial impedance or accelerate Li... + While compound 1 is used to improve high-rate performance, it cannot suppress electrolyte oxidation and decomposition, transition metal dissolution, and HF corrosion. It can only exist as an inert ionic liquid, and the inertness of the alkyl chain increases interfacial impedance. Furthermore, it cannot improve the SEI impedance spike at low temperatures, ultimately leading to a significant decrease in key battery performance characteristics such as high-rate cycle capacity retention and low-temperature cycle capacity retention. When compound 1 is replaced with compound B, performance deteriorates. This may be because compound B is 1-(N,N-dimethylcarbamoylmethyl)-1-methylpiperidinium trifluoromethanesulfonate, whose structure also lacks the core -N of the original first additive. + The -SO2F active group, with an amide-substituted piperidinium cation and a trifluoromethanesulfonate anion, is completely incompatible with the film-forming mechanism of the original additive. The reduction potentials of its amide group and trifluoromethanesulfonate are vastly different from those of -SO2F, making it impossible to form a stable, highly conductive SEI film on the negative electrode surface. Instead, it decomposes to generate high-impedance organic byproducts, significantly increasing interfacial impedance and deteriorating the Li... + The transport efficiency is lower, while the chemical stability of trifluoromethanesulfonate is weaker than that of the original additive PF5. - / BF5 - At high potentials, it is easier to decompose, which will aggravate electrolyte oxidation, HF generation and positive electrode transition metal dissolution. In addition, the amide side chain increases the cation volume and reduces ionic conductivity. Multiple factors work together to cause a significant decline in battery performance such as high-rate cycling and low-temperature cycling capacity retention.

[0046] As can be seen from the comparison of Example 9 and Comparative Examples 4-5, when the first additive of the present invention and DTD are used in combination with LiDFBP / FEC, the improvement of electrochemical performance is not significant. This also shows that not all film-forming aids have the effect of improving high-rate cycling and low-temperature performance when combined with the first additive of the present invention.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A non-aqueous electrolyte, characterized in that, It includes lithium salts, non-aqueous organic solvents, and additives, said additives including a first additive having the structure shown in Formula I. Formula I Among them, M + Selected from heterocyclic ononium cations containing tertiary amine nitrogen, aliphatic tertiary amine ononium cations, or N,N-dialkyl-substituted amide ononium cations, Q - It contains fluorine anionic groups.

2. The non-aqueous electrolyte according to claim 1, characterized in that, M + Selected from pyridinium cations, N-methylpyrrolonnium cations, thiazonnium cations, triethylaminennium cations, triallylaminennium cations, N,N-dimethylformamidennium cations, N,N-dimethylacetamidennium cations, or N,N-dimethylacrylamidennium cations, Q - It is selected from hexafluorophosphate, difluorophosphate, tetrafluoroborate, difluorosulfonylimide or ditrifluoromethylsulfonylimide.

3. The non-aqueous electrolyte according to claim 1 or 2, characterized in that, The first additive includes at least one of the following compounds 1 to 6. Compound 1, Compound 2, Compound 3 Compound 4, Compound 5, Compound 6.

4. The non-aqueous electrolyte according to claim 1 or 2, characterized in that, The first additive has a mass percentage of 0.1% to 5% in the non-aqueous electrolyte.

5. The non-aqueous electrolyte according to claim 1 or 2, characterized in that, The additive also includes a second additive, which is lithium difluorobis(oxalato) phosphate, and the mass percentage of the lithium difluorobis(oxalato) phosphate in the non-aqueous electrolyte is 0.1% to 4.5%.

6. The non-aqueous electrolyte according to claim 1 or 2, characterized in that, The additive also includes a third additive, which is fluoroethylene carbonate, and the fluoroethylene carbonate has a mass percentage of 0.1% to 5.5% in the non-aqueous electrolyte.

7. The non-aqueous electrolyte according to claim 1 or 2, characterized in that, The lithium salt includes at least one of lithium dioxaborate, lithium hexafluorophosphate, lithium difluorooxaborate, lithium tetrafluoroborate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium methanesulfonate, lithium trifluoromethanesulfonate, lithium fluorosulfonate, lithium perchlorate, and lithium difluorophosphate.

8. The non-aqueous electrolyte according to claim 1 or 2, characterized in that, The non-aqueous organic solvent includes at least one of carbonates, carboxylic esters, and ethers.

9. The non-aqueous electrolyte according to claim 8, characterized in that, The non-aqueous organic solvent includes at least one of propylene carbonate, butyl carbonate, pentylenetene carbonate, vinylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl n-propyl carbonate, ethyl n-propyl carbonate, propylene carbonate, ethylene carbonate, γ-butyrolactone, γ-valerolactone, δ-valerolactone, methyl acetate, ethyl acetate, ethyl propionate, butyl acetate, propyl propionate, butyl propionate, 2-trifluoromethyltetrahydrofuran, dimethoxymethane, diethoxymethane, 1,3-dioxolane, 1,4-dioxane, ethoxymethoxymethane, crown ether, tetrahydrofuran, 2-methyltetrahydrofuran, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether.

10. A secondary battery, characterized in that, Includes the non-aqueous electrolyte as described in any one of claims 1 to 9.

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