An electrolyte and a battery containing the electrolyte

Abstract

The present invention provides an electrolyte and a battery containing the electrolyte. In the electrolyte provided by the present invention, the combination of an α-carbonylsulfide ylide compound and a sulfonyldiimidazole compound can effectively form a tough, non-breakable, and high-temperature resistant interface film on the surfaces of the positive and negative electrodes, thereby improving the oxidation resistance of the electrolyte, optimizing the positive electrode / electrolyte interface, reducing the surface activity of the positive electrode, inhibiting the decomposition of the electrolyte under high voltage and high temperature conditions, and thus inhibiting the gas production during the battery's circulation process under high voltage and high temperature conditions. In addition, the interface film can effectively inhibit the dissolution of transition metals (Ni, Co, Al, and Mn); and significantly improves the high-temperature storage, cycle performance, and low-temperature discharge performance of the battery under high voltage (4.45V and above) systems.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium ion batteries, and in particular relates to an electrolyte and a battery containing the electrolyte. Background Art

[0002] Lithium-ion batteries, due to their high specific energy, lack of memory effect, and long cycle life, are widely used in 3C digital products, power tools, aerospace, energy storage, and electric vehicles. Ternary cathode materials (such as nickel-cobalt-manganese (NCM) or nickel-cobalt-aluminum (NCA)) have become the preferred cathode active material for lithium-ion batteries due to their safety and low price. However, with the development and popularization of higher-voltage lithium-ion batteries, the electrical performance requirements for lithium-ion batteries are becoming increasingly stringent.

[0003] Currently, lithium-ion batteries face some challenges in high-voltage (4.45V and above) systems: For example, it has been found that at a high voltage of 4.35V, ternary cathode materials face problems such as poor high-temperature storage, poor normal-high-temperature cycle performance, and severe cycle gas generation. This may be because the newly developed coating or doping technology is not perfect. As the charging voltage increases, the dissolution of transition metals in the ternary cathode material becomes more and more serious. At the same time, there is also the problem of electrolyte matching. For example, conventional electrolytes will oxidize and decompose on the surface of the battery cathode at a high voltage of 4.45V. Under high temperature conditions, the oxidative decomposition of the electrolyte will be accelerated, and at the same time, the deterioration reaction of the ternary cathode material will be promoted.

[0004] Therefore, there is an urgent need to develop an electrolyte that can effectively inhibit cyclic gas production, improve the high-temperature storage and normal high-temperature cycling performance of the battery in a high-voltage (4.45V and above) system, and inhibit cyclic gas production, thereby ensuring the excellent electrical performance of the ternary lithium-ion battery. Summary of the Invention

[0005] In order to improve the deficiencies of the prior art, the present invention aims to provide an electrolyte and a battery containing the electrolyte. The present invention uses a combination of α-carbonylsulfide ylide compounds and sulfonyldiimidazole compounds to effectively form a tough, non-breakable, and high-temperature resistant interface film on the surfaces of the positive and negative electrodes. On the one hand, the oxidation resistance of the electrolyte is improved, the positive electrode / electrolyte interface is optimized, the activity of the positive electrode surface is reduced, and the decomposition of the electrolyte under high voltage and high temperature conditions is inhibited, thereby inhibiting the gas production during the battery cycle under high voltage and high temperature conditions; on the other hand, the interface film can effectively inhibit the dissolution of transition metals (Ni, Co, Al, and Mn); in addition, the interface film formed by the electrolyte on the negative electrode surface has low impedance and has a good lithium ion conduction channel. Therefore, the electrolyte of the present invention can significantly improve the high-temperature storage and normal high-temperature cycle performance of the battery in a high voltage (4.45V and above) system, inhibit cyclic gas production, and also take into account the low-temperature discharge performance.

[0006] The object of the present invention is achieved through the following technical solutions:

[0007] An electrolyte comprises an electrolyte salt, an organic solvent and an additive, wherein the additive comprises an α-carbonylsulfide ylide compound and a sulfonyldiimidazole compound.

[0008] According to an embodiment of the present invention, the electrolyte is used in a nickel-cobalt-manganese battery or a nickel-cobalt-aluminum battery.

[0009] According to an embodiment of the present invention, the α-carbonylsulfide ylide compound is selected from at least one of the compounds represented by Formula 1:

[0010]

[0011] In Formula 1, R1 is a substituted or unsubstituted heteroaryl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted cycloalkyl group; if substituted, the substituent is a halogen or an alkyl group.

[0012] According to an embodiment of the present invention, R1 is a substituted or unsubstituted 5-20 membered heteroaryl, a substituted or unsubstituted C 6-20 Aryl, substituted or unsubstituted C 1-12 Alkyl, substituted or unsubstituted C 3-20 Cycloalkyl; if substituted, the substituent is halogen or C 1-12 alkyl.

[0013] According to an embodiment of the present invention, R1 is a substituted or unsubstituted 5-10 membered heteroaryl, a substituted or unsubstituted C 6-10 Aryl, substituted or unsubstituted C 1-6 Alkyl, substituted or unsubstituted C 3-10 Cycloalkyl; if substituted, the substituent is halogen or C 1-6 alkyl.

[0014] According to an embodiment of the present invention, R1 is a substituted or unsubstituted 5-6 membered heteroaryl, a substituted or unsubstituted C 6-8 Aryl, substituted or unsubstituted C 1-3 Alkyl, substituted or unsubstituted C 3-6 Cycloalkyl; if substituted, the substituent is halogen or C 1-6 alkyl.

[0015] According to an embodiment of the present invention, R1 is furyl, thienyl, isopropyl, cyclopropyl, 4-fluorophenyl, or 4-trifluoromethylphenyl.

[0016] According to an embodiment of the present invention, the α-carbonylsulfide ylide compound is selected from at least one of Compounds A to F:

[0017]

[0018] According to an embodiment of the present invention, the sulfonyl diimidazole compound is selected from at least one of the compounds shown in Formula 2:

[0019]

[0020] In formula 2, n1 is 0, 1, 2 or 3; n2 is 0, 1, 2 or 3;

[0021] R4 and R5 are the same or different and are independently selected from H, halogen, cyano, unsubstituted or optionally substituted by one, two or more R' a Substituted with the following groups: C 1-6 Alkyl, C 2-6 Alkenyl, C 1-6 Alkoxy, C 1-6 Alkoxycarbonyl, sulfonic acid group (-SO3H); each R' a the same or different, independently selected from halogen, C 1-6 alkyl.

[0022] According to an embodiment of the present invention, in Formula 2, R4 and R5 are the same or different and are independently selected from H, propenyl, halogen, C 1-3 Alkyl, methoxy, trifluoromethyl, C 1-3 Alkoxycarbonyl, cyano or -SO3F.

[0023] According to an embodiment of the present invention, the α-carbonylsulfide ylide compound and the sulfonyldiimidazole compound can be purchased through commercial channels or prepared by methods known in the art.

[0024] According to an embodiment of the present invention, the mass of the α-carbonylsulfide ylide compound accounts for 0.1 to 0.5 wt% of the total mass of the electrolyte, such as 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt% or any point value in the range consisting of any two of the above point values.

[0025] According to an embodiment of the present invention, the mass of the sulfonyldiimidazole compound accounts for 0.5 to 3 wt % of the total mass of the electrolyte, for example, 0.1 wt %, 0.2 wt %, 0.5 wt %, 1.0 wt %, 1.2 wt %, 1.5 wt %, 1.7 wt %, 1.8 wt %, 2 wt %, 2.2 wt %, 2.4 wt %, 2.5 wt %, 2.7 wt %, 3 wt % or any point value in the range consisting of any two of the above point values.

[0026] According to an embodiment of the present invention, the sulfonyldiimidazole compound is selected from at least one of Compounds 1 to 6 shown below:

[0027]

[0028]

[0029] According to an embodiment of the present invention, the electrolyte salt is selected from at least one of electrolyte lithium salt, electrolyte sodium salt, electrolyte magnesium salt, and the like.

[0030] According to an embodiment of the present invention, the electrolyte lithium salt is selected from at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium difluorooxalatophosphate, lithium tetrafluoroborate, lithium tetrafluorooxalatophosphate, lithium bis(trifluoromethylsulfonyl imide) and lithium bis(fluorosulfonyl imide).

[0031] According to an embodiment of the present invention, the mass of the electrolyte salt accounts for 13-20 wt.% of the total mass of the electrolyte, for example, 13 wt.%, 14 wt.%, 15 wt.%, 16 wt.%, 17 wt.%, 18 wt.%, 19 wt.% or 20 wt.%.

[0032] According to an embodiment of the present invention, the organic solvent is selected from at least two of propylene carbonate, ethyl methyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, fluoroethylene carbonate, γ-butyrolactone, cyclopentane, methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, and butyl butyrate.

[0033] The present invention also provides a battery, comprising the above-mentioned electrolyte.

[0034] According to an embodiment of the present invention, the battery is a lithium-ion battery.

[0035] According to an embodiment of the present invention, the battery further includes a positive electrode sheet containing a positive electrode active material, a negative electrode sheet containing a negative electrode active material, and a separator.

[0036] According to an embodiment of the present invention, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer coated on one or both sides of the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material, a conductive agent, and a binder.

[0037] According to an embodiment of the present invention, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on one or both sides of the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material, a conductive agent, and a binder.

[0038] According to an embodiment of the present invention, the mass percentage of each component in the positive electrode active material layer is: 80-99.8 wt % of positive electrode active material, 0.1-10 wt % of conductive agent, and 0.1-10 wt % of binder.

[0039] Preferably, the mass percentage of each component in the positive electrode active material layer is: 90-99.6 wt % of positive electrode active material, 0.2-5 wt % of conductive agent, and 0.2-5 wt % of binder.

[0040] According to an embodiment of the present invention, the mass percentage of each component in the negative electrode active material layer is: 80-99.8 wt % of negative electrode active material, 0.1-10 wt % of conductive agent, and 0.1-10 wt % of binder.

[0041] Preferably, the mass percentage of each component in the negative electrode active material layer is: 90-99.6 wt % of negative electrode active material, 0.2-5 wt % of conductive agent, and 0.2-5 wt % of binder.

[0042] According to an embodiment of the present invention, the conductive agent is selected from at least one of conductive carbon black, acetylene black, Ketjen black, conductive graphite, conductive carbon fiber, carbon nanotubes, and metal powder.

[0043] According to an embodiment of the present invention, the binder is selected from at least one of sodium carboxymethyl cellulose, styrene-butadiene latex, polytetrafluoroethylene, and polyethylene oxide.

[0044] According to an embodiment of the present invention, the positive electrode active material is selected from LiNi x Co y Mn z M 1 (1-x-y-z) O2 or LiNi x Co y Al z M 2 (1-x-y-z) O2, where M 1 is any one of Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V and Ti, M 2 Any one of Mn, Mg, Cu, Zn, Sn, B, Ga, Cr, Sr, V and Ti, 0.5≤x<1, 0 <y≤1,0<z≤1,x+y+z≤1。

[0045] According to an embodiment of the present invention, the negative electrode active material is selected from at least one of artificial graphite, natural graphite, hard carbon, soft carbon, mesophase carbon microbeads, silicon-based negative electrode materials and lithium-containing metal composite oxide materials.

[0046] According to an embodiment of the present invention, the charging cut-off voltage of the battery is 4.45V or above.

[0047] Beneficial effects of the present invention:

[0048] The present invention provides an electrolyte and a battery containing the electrolyte. In the electrolyte provided by the present invention, the combination of α-carbonylsulfide ylide compounds and sulfonyldiimidazole compounds can effectively form an interface film on the surface of the positive and negative electrodes that is tough, not easy to break, and has strong high-temperature resistance, thereby improving the oxidation resistance of the electrolyte, optimizing the positive electrode / electrolyte interface, reducing the surface activity of the positive electrode, inhibiting the decomposition of the electrolyte under high voltage and high temperature conditions, and thus inhibiting the gas production during the battery cycle under high voltage and high temperature conditions. Moreover, the interface film can effectively inhibit the dissolution of transition metals (Ni, Co, Al and Mn). In addition, the sulfonyldiimidazole compound is also conducive to forming a uniform and dense interface film on the surface of the positive electrode active material, reducing the phenomenon of uneven Li+ embedding in the positive electrode. At the same time, the sulfonyldiimidazole compound can also be reduced on the surface of the negative electrode material (reduction potential is: 1.5V vs Li+ / Li) to form a dense and stable SEI film, reducing the reduction decomposition of the electrolyte on the surface of the negative electrode material. In short, the two simultaneously undergo redox reactions at the positive and negative electrode interfaces in preference to the solvent to form an interfacial film, which optimizes the composition of the positive and negative electrode interfacial films, improves the thermal stability of the interfacial films, and reduces the migration resistance of lithium ions. They work together to significantly improve the high-temperature storage, cycle performance, and low-temperature discharge performance of the battery in high-voltage (4.45V and above) systems. DETAILED DESCRIPTION

[0049] The present invention will be described in further detail below with reference to specific examples. It should be understood that the following examples are merely illustrative and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection that the present invention is intended to protect.

[0050] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the reagents, materials, etc. used in the following examples are all commercially available unless otherwise specified.

[0051] Lithium-ion battery preparation

[0052] (1) Preparation of positive electrode sheet

[0053] The positive electrode active material lithium nickel cobalt manganese oxide ternary material LiNi 0.5 Mn 0.3 Co 0.2O2 (NCM523), binder polyvinylidene fluoride (PVDF), and conductive agent acetylene black are mixed in a weight ratio of 96.5:2:1.5, N-methylpyrrolidone (NMP) is added, and stirred under the action of a vacuum mixer until the mixed system becomes a positive electrode slurry with uniform fluidity; the positive electrode slurry is evenly coated on an aluminum foil with a thickness of 12μm; the coated aluminum foil is baked in an oven with 5 different temperature gradients, and then dried in an oven at 120°C for 8h, and then rolled and die-cut to obtain a positive electrode sheet.

[0054] (2) Preparation of negative electrode sheet

[0055] The negative electrode active material artificial graphite, thickener sodium carboxymethyl cellulose (CMC-Na), binder styrene-butadiene rubber, conductive agent acetylene black, and conductive agent single-walled carbon nanotube (SWCNT) were mixed in a weight ratio of 95.9:1:1.8:1:0.3, and deionized water was added to obtain a negative electrode slurry under the action of a vacuum mixer; the negative electrode slurry was evenly coated on a copper foil with a thickness of 8 μm; and the negative electrode sheet was obtained after drying (temperature: 85°C, time: 5 h), rolling, and die-cutting.

[0056] (3) Preparation of electrolyte

[0057] In an argon-filled glove box (moisture <10 ppm, oxygen <1 ppm), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a mass ratio of 25:60:15. Fully dried lithium hexafluorophosphate (14.5 wt % based on the total mass percentage of the electrolyte) and additives (specific amounts and selections are shown in Table 1) were quickly added to the mixed solution and stirred to obtain an electrolyte.

[0058] (4) Preparation of diaphragm

[0059] A coated polyethylene diaphragm with a thickness of 8 μm was selected.

[0060] (5) Preparation of lithium-ion batteries

[0061] The positive electrode sheet, separator and negative electrode sheet prepared above are wound to obtain a bare cell without liquid injection; the bare cell is placed in an outer packaging foil, and the prepared electrolyte is injected into the dried bare cell. After vacuum packaging, standing, formation, secondary sealing, sorting and other processes, the required lithium-ion battery is obtained.

[0062] The lithium ion batteries of Comparative Examples 1-2 and Examples 1-15 were all prepared according to the above preparation method. The specific lithium salt and additive combinations and contents are shown in Table 1.

[0063] The electrochemical performance test results of the lithium ion batteries of Comparative Examples 1-2 and Examples 1-15 are shown in Table 2.

[0064] Table 1 Composition of the electrolyte of the lithium ion battery of Comparative Examples 1-2 and Examples 1-15

[0065]

[0066]

[0067] (1) 25°C cycle test: The batteries obtained in the above examples and comparative examples were placed in a (25±2)°C environment and allowed to stand for 2-3 hours. When the battery body reached (25±2)°C, the battery was charged to 4.45V at a constant current and constant voltage of 1C with a cutoff current of 0.05C. After the battery was fully charged, it was left for 5 minutes and then discharged at a constant current of 1C to a cutoff voltage of 3.0V. The highest discharge capacity of the first three cycles was recorded as the initial capacity Q. When the cycle reached the required number of times, the last discharge capacity Q1 of the battery was recorded. The recorded results are shown in Table 2.

[0068] The calculation formula used is as follows: Capacity retention rate (%) = Q1 / Q×100%.

[0069] (2) 45°C cycle test: The batteries obtained in the above examples and comparative examples were placed in a (45±2)°C environment and allowed to stand for 2-3 hours. When the battery body reached (45±2)°C, the battery was charged to 4.45V at a constant current and constant voltage of 1C with a cutoff current of 0.05C. After the battery was fully charged, it was left for 5 minutes and then discharged at a constant current of 1C to a cutoff voltage of 3.0V. The highest discharge capacity of the first three cycles was recorded as the initial capacity Q. When the cycle reached the required number of times, the last discharge capacity Q1 of the battery was recorded. The recorded results are shown in Table 2.

[0070] The calculation formula used is as follows: Capacity retention rate (%) = Q1 / Q×100%.

[0071] (3) Low-temperature discharge performance test: At room temperature (25°C), the lithium-ion battery was charged and discharged at 0.5C / 0.5C (the discharge capacity was recorded as C0), with an upper limit voltage of 4.45V. The battery was then charged to 4.45V under 0.5C constant current and constant voltage conditions. The lithium-ion battery was placed in a -20°C low-temperature box for 4 hours and discharged at 0.5C at -20°C (the discharge capacity was recorded as C1). The results are recorded in Table 2.

[0072] The calculation formula used is as follows: low temperature discharge capacity retention rate (%) = Q1 / Q0×100%.

[0073] (4) High temperature storage test: At room temperature (25°C), the lithium-ion battery is charged and discharged at 0.3C / 0.3C (the battery discharge capacity is recorded as C0), with an upper limit voltage of 4.45V; the battery is placed in a 60°C constant temperature box for 30 days, the battery is taken out, and the battery is placed in a 25°C environment and discharged at 0.3C, and the discharge capacity is recorded as C1; then the lithium-ion battery is charged and discharged at 0.3C / 0.3C (the battery discharge capacity is recorded as C2), and the capacity retention rate and capacity recovery rate of the lithium-ion battery are calculated using the following formula;

[0074] Capacity retention rate = (C1 / C0)*100%;

[0075] Capacity recovery rate = (C2 / C0)*100%;

[0076] The recorded results are shown in Table 2.

[0077] High-temperature storage thickness expansion test: At room temperature (25°C), the lithium-ion battery is charged and discharged at a 0.3C / 0.3C rate with an upper voltage limit of 4.45V. After discharge, the battery thickness is measured and recorded as D0. The battery is placed in a 60°C oven for 30 days. The battery is then removed and the battery thickness is measured and recorded as D1.

[0078] Thickness expansion rate = ((D1-D0) / D0)*100%;

[0079] The recorded results are shown in Table 2.

[0080] Table 2 Performance test results of lithium ion batteries of Comparative Examples 1-2 and Examples 1-15

[0081]

[0082]

[0083] Based on the above embodiments and comparative examples, it can be seen that the combination of α-carbonylsulfide ylide compounds and sulfonyldiimidazole compounds in the electrolytes provided in Examples 1-15 can effectively form an interface film rich in components such as Li2SO3 and LiOCO2R on the surfaces of the positive and negative electrodes, thereby improving the oxidation resistance of the electrolyte, optimizing the positive electrode / electrolyte interface, reducing the surface activity of the positive electrode, and inhibiting the decomposition of the electrolyte under high voltage and high temperature conditions of 4.45V, thereby inhibiting the gas production of lithium-ion batteries during high temperature and high voltage cycling. Moreover, the interface film can effectively inhibit the dissolution of transition metals (Ni, Co and Mn); in addition, the sulfonyldiimidazole compound is also beneficial to the formation of a uniform and dense interface film on the surface of the positive electrode active material, reducing the uneven embedding of Li+ at the positive electrode. At the same time, the sulfonyldiimidazole compound can also be reduced on the surface of the negative electrode material (reduction potential is: 1.5V vs Li+ / Li) to form a dense and stable SEI film, reducing the reduction decomposition of the electrolyte on the surface of the negative electrode material. In short, the two simultaneously undergo redox reactions at the positive and negative electrode interfaces in preference to the solvent to form an interfacial film, which optimizes the composition of the positive and negative electrode interfacial films, improves the thermal stability of the interfacial films, and reduces the migration resistance of lithium ions. They work together to significantly improve the high-temperature storage, cycle performance, and low-temperature discharge performance of the battery in high-voltage (4.45V and above) systems.

[0084] In Example 2, due to the low content of α-carbonylsulfide ylide compounds, low-temperature discharge, cycling, and storage performance decreased. In Example 3, due to the high content of α-carbonylsulfide ylide compounds, impedance increased, and room-temperature cycling and low-temperature discharge performance decreased. In Example 4, due to the low content of sulfonyldiimidazole compounds, high-temperature cycling performance decreased. In Example 5, due to the high content of sulfonyldiimidazole compounds, impedance increased, and room-temperature cycling and low-temperature discharge performance decreased.

[0085] Comparative Example 1 does not contain α-carbonylsulfide ylide compounds, resulting in decreased cycle life, low-temperature discharge, and high-temperature storage performance. Comparative Example 2 does not contain sulfonyldiimidazole compounds, resulting in decreased cycle life, low-temperature discharge, and high-temperature storage performance.

[0086] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. An electrolyte, characterized in that: The electrolyte comprises an electrolyte salt, an organic solvent and an additive, wherein the additive comprises an α-carbonylsulfide ylide compound and a sulfonyldiimidazole compound; The α-carbonylsulfide ylide compound is selected from at least one of the compounds shown in Formula 1: In Formula 1, R1 is a substituted or unsubstituted heteroaryl, a substituted or unsubstituted aryl, a substituted or unsubstituted alkyl, or a substituted or unsubstituted cycloalkyl; if substituted, the substituent is a halogen or an alkyl; The sulfonyldiimidazole compound is selected from at least one of the compounds shown in Formula 2: In formula 2, n1 is 0, 1, 2 or 3; n2 is 0, 1, 2 or 3; R4 and R5 are the same or different and are independently selected from H, halogen, cyano, unsubstituted or optionally substituted by one, two or more R' a Substituted with the following groups: C 1-6 Alkyl, C 2-6 Alkenyl, C 1-6 Alkoxy, C 1-6 Alkoxycarbonyl, sulfonic acid -SO3H; each R' a the same or different, independently selected from halogen, C 1-6 alkyl.

2. The electrolyte according to claim 1, characterized in that R1 is a substituted or unsubstituted 5-20 membered heteroaryl, a substituted or unsubstituted C 6-20 Aryl, substituted or unsubstituted C 1-12 Alkyl, substituted or unsubstituted C 3-20 Cycloalkyl; if substituted, the substituent is halogen or C 1-12 alkyl.

3. The electrolyte according to claim 2, characterized in that The α-carbonylsulfide ylide compound is selected from at least one of Compound A to Compound F:

4. The electrolyte according to claim 1, characterized in that In formula 2, R4 and R5 are the same or different and are independently selected from H, propenyl, halogen, C 1-3 Alkyl, methoxy, trifluoromethyl, C 1-3 Alkoxycarbonyl, cyano or -SO3F.

5. The electrolyte according to claim 1, characterized in that The mass of the α-carbonylsulfide ylide compound accounts for 0.1 to 0.5 wt % of the total mass of the electrolyte.

6. The electrolyte according to claim 1 or 5, characterized in that The mass of the sulfonyldiimidazole compound accounts for 0.5 to 3 wt % of the total mass of the electrolyte.

7. A battery, characterized in that: The battery comprises the electrolyte according to any one of claims 1 to 6.

8. The battery according to claim 7, characterized in that The battery also includes a positive electrode sheet containing a positive electrode active material, wherein the positive electrode active material is selected from LiNi x Co y Mn z M 1 (1-x-y-z) O2 or LiNi x Co y Al z M 2 (1-x-y-z) O2, where M 1 is any one of Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V and Ti, M 2 Any one of Mn, Mg, Cu, Zn, Sn, B, Ga, Cr, Sr, V and Ti, 0.5≤x<1, 0 <y≤1,0<z≤1,x+y+z≤1; And / or, the charging cut-off voltage of the battery is 4.45V or above.

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