Electrolyte and battery containing the same

Abstract

The present invention provides an electrolyte and a battery containing the electrolyte. In the electrolyte provided by the present invention, a nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group is a bifunctional additive. The nitrogen atom of the nitrogen-containing heterocyclic compound has a lone electron pair. When added in small amounts to the electrolyte, the compound exhibits a weak Lewis base and can form a complex (e.g., a hexaligand complex) with other components in the electrolyte (e.g., PF5), reducing the acidity and reactivity of the electrolyte and suppressing the increase in free acid in the electrolyte. The electrolyte can improve the high-temperature cycle performance, room-temperature cycle performance, low-temperature discharge performance, and rate performance of high-voltage batteries while suppressing lithium deposition at the negative electrode.

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] Secondary batteries offer significant advantages, including high specific energy, high specific power, long cycle life, and low self-discharge. Lithium-ion batteries are a common type of secondary battery. The cathode materials used in commercial lithium-ion batteries primarily include lithium manganese oxide, lithium cobalt oxide, ternary materials, and lithium iron phosphate. Their charge cutoff voltage generally does not exceed 4.2V. With technological advancements and the continuous development of the market, improving the energy density of lithium-ion batteries is becoming increasingly important and urgent.

[0003] In addition to improving existing materials and battery manufacturing processes, high-voltage (4.35V-5V) cathode materials are a popular research direction. This approach achieves high energy density by increasing the depth of charge of the cathode active material. However, as the operating voltage of ternary material batteries increases, the battery's performance, such as charge and discharge cycling, deteriorates. The electrolyte, as a crucial component of lithium-ion batteries, significantly impacts the degradation of battery performance, such as charge and discharge cycling. The electrolyte determines the migration rate of lithium ions (Li+) in the liquid phase and also participates in the formation of the solid electrolyte interface (SEI) film, playing a critical role in SEI film performance. Therefore, under high-voltage conditions, the electrolyte can lead to poor high-temperature storage performance, poor high-temperature cycling performance, and poor room-temperature cycling performance of lithium-ion batteries. Furthermore, at low temperatures, the electrolyte's viscosity increases, its conductivity decreases, and the SEI film's resistance increases. Consequently, the electrolyte can also lead to poor low-temperature discharge performance of lithium-ion batteries, even creating the risk of low-temperature lithium deposition. Therefore, there is an urgent need to develop an electrolyte with excellent performance across all aspects to meet the requirements of high-energy-density ternary material batteries. Summary of the Invention

[0004] To address the deficiencies of the prior art, the present invention provides an electrolyte and a battery containing the electrolyte. The present invention introduces a nitrogen-containing heterocyclic compound containing a sulfonate or sulfone group into the electrolyte to improve the high-temperature cycling performance, room-temperature cycling performance, low-temperature discharge performance, and rate performance of high-voltage batteries (particularly nickel-cobalt-manganese ternary material batteries or nickel-cobalt-aluminum ternary material batteries) above 4.35V, while also suppressing lithium plating at the negative electrode.

[0005] Furthermore, by introducing a combination of nitrogen-containing heterocyclic compounds containing sulfonate groups or sulfone groups and fluorinated cyclic carbonate compounds into the electrolyte, the further consumption of the single fluorinated cyclic carbonate compound in the electrolyte and the reaction between the electrolyte and the negative electrode interface can be effectively avoided, thereby further enhancing the high-temperature cycle performance, room-temperature cycle performance, low-temperature discharge performance and rate performance of high-voltage batteries above 4.35V while suppressing lithium plating at the negative electrode.

[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 a nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group.

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

[0009] According to an embodiment of the present invention, the nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group includes a sulfonate group or a sulfone group, and the sulfur and nitrogen in the sulfonate group or the sulfone group form a heterocyclic structure.

[0010] According to an embodiment of the present invention, the electrolyte further includes a fluorinated cyclic carbonate compound.

[0011] According to an embodiment of the present invention, the fluorinated cyclic carbonate compound includes a carbonate group, and the carbonate group and the alkyl group form a cyclic structure.

[0012] According to an embodiment of the present invention, the nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group is selected from at least one of the compounds shown in Formula 1:

[0013]

[0014] In formula 1, X is -O- or -N(R2)-;

[0015] R1 is halogen, substituted or unsubstituted alkyl. If substituted, the substituent is halogen or alkyl;

[0016] R2 is a substituted or unsubstituted aryl group, a substituted or unsubstituted alkyl group. If it is substituted, the substituent is halogen or alkyl group.

[0017] According to an embodiment of the present invention, R1 is halogen, substituted or unsubstituted C 1-12 Alkyl, if substituted, the substituent is halogen, C 1-12 alkyl;

[0018] R2 is substituted or unsubstituted C 6-20 Aryl, substituted or unsubstituted C 1-12Alkyl, if substituted, the substituent is halogen, C 1-12 alkyl.

[0019] According to an embodiment of the present invention, R1 is halogen, substituted or unsubstituted C 1-6 Alkyl, if substituted, the substituent is halogen, C 1-6 alkyl;

[0020] R2 is substituted or unsubstituted C 6-10 Aryl, substituted or unsubstituted C 1-6 Alkyl, if substituted, the substituent is halogen, C 1-6 alkyl.

[0021] According to an embodiment of the present invention, R1 is halogen, substituted or unsubstituted C 1-3 Alkyl, if substituted, the substituent is halogen, C 1-3 alkyl;

[0022] R2 is substituted or unsubstituted phenyl, substituted or unsubstituted C 1-3 Alkyl, if substituted, the substituent is halogen, C 1-3 alkyl.

[0023] According to an embodiment of the present invention, the nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group is selected from at least one of Compounds A to F:

[0024]

[0025]

[0026] According to an embodiment of the present invention, the nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group can be purchased from commercial sources or prepared by methods known in the art.

[0027] According to an embodiment of the present invention, the mass of the nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group 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.

[0028] According to an embodiment of the present invention, the fluorinated cyclic carbonate compound is selected from at least one of the compounds shown in Formula 2:

[0029]

[0030] In formula 2, R3 and R4 are the same or different and are independently selected from H, F, substituted or unsubstituted alkyl, and contain at least one F atom. If substituted, the substituent is F or alkyl.

[0031] According to an embodiment of the present invention, in Formula 2, R3 and R4 are the same or different and are independently selected from H, F, substituted or unsubstituted C 1-6 Alkyl, and contains at least one F atom, if substituted, the substituent is F, C 1-6 alkyl.

[0032] According to an embodiment of the present invention, in Formula 2, R3 and R4 are the same or different and are independently selected from H, F, substituted or unsubstituted C 1-3 Alkyl, and contains at least one F atom, if substituted, the substituent is F, C 1-3 alkyl.

[0033] According to an embodiment of the present invention, the fluorinated cyclic carbonate compound can be purchased from commercial sources or prepared by methods known in the art.

[0034] According to an embodiment of the present invention, the mass of the fluorinated cyclic carbonate compound accounts for 1wt% to 10wt% of the total mass of the electrolyte, for example, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt% or any point value in the range consisting of any two of the above point values.

[0035] According to an embodiment of the present invention, the fluorinated cyclic carbonate compound is selected from at least one of Compounds 1 to 3 shown below:

[0036]

[0037] 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.

[0038] 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).

[0039] 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%.

[0040] 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.

[0041] The present invention also provides a battery, comprising the above-mentioned electrolyte.

[0042] According to an embodiment of the present invention, the battery is a lithium-ion battery.

[0043] According to an embodiment of the present invention, the battery is a nickel-cobalt-manganese ternary battery or a nickel-cobalt-aluminum ternary battery.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] According to an embodiment of the present invention, the mass percentages of the components in the negative electrode active material layer are: 80-99.8 wt % of the negative electrode active material, 0.1-10 wt % of the conductive agent, and 0.1-10 wt % of the binder.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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。

[0054] 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.

[0055] According to an embodiment of the present invention, the charging cut-off voltage of the battery is 4.35V or above.

[0056] Beneficial effects of the present invention:

[0057] The present invention provides an electrolyte and a battery containing the electrolyte. In the electrolyte provided by the present invention, a nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group is a bifunctional additive. There is a lone electron pair on the N atom of the nitrogen-containing heterocyclic compound. When added in small amounts to the electrolyte, it can exhibit a weak Lewis alkalinity and can form a complex (such as a hexaligand complex) with other components in the electrolyte (such as PF5), thereby reducing the acidity and reaction activity of the electrolyte and inhibiting the increase of free acid in the electrolyte. At the same time, the nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group can form a large amount of LiSO3, ROSO2Li, Li x N y O zThe outer interface film has good high temperature resistance and low impedance, which is conducive to the migration of lithium ions. It can improve the high temperature cycle performance, room temperature cycle performance, low temperature discharge performance and rate performance of high voltage batteries while inhibiting lithium plating at the negative electrode.

[0058] On this basis, when nitrogen-containing heterocyclic compounds containing sulfonate groups or sulfone groups and fluorinated cyclic carbonate compounds are added to the electrolyte at the same time, a synergistic effect is produced between the two. The two act together on the surfaces of the positive and negative electrodes, which can further enhance the high-temperature cycle performance, room-temperature cycle performance, low-temperature discharge performance and rate performance of the high-voltage battery while inhibiting lithium plating at the negative electrode, and can effectively avoid the further consumption of a single fluorinated cyclic carbonate compound in the electrolyte and the reaction between the electrolyte and the negative electrode interface. DETAILED DESCRIPTION

[0059] 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.

[0060] 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.

[0061] Lithium-ion battery preparation

[0062] (1) Preparation of positive electrode sheet

[0063] The positive electrode active material lithium nickel cobalt manganese oxide ternary material LiNi 0.6 Mn 0.2 Co 0.2 O2 (NCM622), 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.

[0064] (2) Preparation of negative electrode sheet

[0065] 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.

[0066] (3) Preparation of electrolyte

[0067] In an argon-filled glove box (moisture <10 ppm, oxygen <1 ppm), ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a mass ratio of 25:5:60:10. 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.

[0068] (4) Preparation of diaphragm

[0069] A coated polyethylene diaphragm with a thickness of 8 μm was selected.

[0070] (5) Preparation of lithium-ion batteries

[0071] 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.

[0072] The lithium ion batteries of Comparative Examples 1-2 and Examples 1-13 were all prepared according to the above preparation method. The specific lithium salt and additive combinations and contents are shown in Table 1.

[0073] The electrochemical performance test results of the lithium ion batteries of Comparative Examples 1-2 and Examples 1-13 are shown in Table 2.

[0074] Table 1 Composition of the electrolyte of the lithium ion battery of Comparative Examples 1-2 and Examples 1-13

[0075]

[0076] (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 4.35V 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.

[0077] The calculation formula used is as follows: Capacity retention rate (%) = Q1 / Q×100%.

[0078] (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 4.35V 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.

[0079] The calculation formula used is as follows: Capacity retention rate (%) = Q1 / Q×100%.

[0080] (3) -10℃ low temperature discharge experiment: At 25℃, the lithium-ion battery was discharged at a constant current of 0.5C to a cut-off voltage of 3V. After standing for 10 minutes, it was charged at a constant current and constant voltage of 1C to 4.35V with a cut-off current of 0.05C. The battery cell was moved to a -10℃ high and low temperature box. After standing for 120 minutes, it was discharged at a constant current of 4C to a cut-off voltage of 3.0V. The inflection point voltage was recorded. The recorded results are shown in Table 2.

[0081] (4) -10℃ cyclic dissection experiment: The batteries obtained from the above examples and comparative examples were placed in a (-10±2)℃ environment and allowed to stand for 2-3 hours. When the battery body reached (-10±2)℃, the battery was charged to 4.35V 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 above steps were repeated for 10 cycles. The dissection record results are shown in Table 2.

[0082] (5) Acidity change experiment after 30-day storage at 60°C: The electrolytes prepared in the above examples and comparative examples were tested for acidity before storage, and then stored in a constant temperature box at 60±2°C for 30 days. The acidity was tested and the results were recorded as shown in Table 2.

[0083] Table 2 Performance test results of lithium ion batteries of Comparative Examples 1-2 and Examples 1-13

[0084]

[0085]

[0086] Based on the above Example 13 and Comparative Example 1, it can be seen that adding nitrogen-containing heterocyclic compounds containing sulfonate groups or sulfone groups to the electrolyte can not only improve the high-temperature cycle performance, room-temperature cycle performance, rate performance and low-temperature discharge performance of the battery, but more importantly, it can effectively avoid low-temperature lithium precipitation. This is because the nitrogen-containing heterocyclic compounds containing sulfonate groups or sulfone groups have lone electron pairs on their N atoms. When added to the electrolyte in small amounts, they can exhibit weak Lewis alkalinity and form complexes (such as hexaligand complexes) with other components in the electrolyte (such as PF5), reducing the acidity and reaction activity of the electrolyte and inhibiting the increase of free acid in the electrolyte; nitrogen-containing heterocyclic compounds containing sulfonate groups or sulfone groups can form large amounts of LiSO3, ROSO2Li, Li at the positive and negative electrodes during the first charge and discharge. x N y O z The outer interface film has good high temperature resistance and low impedance, which is conducive to the migration of lithium ions. The fluorinated cyclic carbonate compounds form an interface film containing LiF and other components at the negative electrode and are evenly dispersed on the surface of the negative electrode.

[0087] Furthermore, it can be seen from Examples 1 to 13 and Comparative Examples 1 to 2 that the interfacial film formed by the nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group can inhibit lithium precipitation and has high stability, and can improve the cycle performance to a certain extent. On this basis, after further adding a fluorinated cyclic carbonate compound, the fluorinated cyclic carbonate compound can form a LiF-rich interfacial film at the negative electrode during the first charge and discharge stage. This interfacial film can significantly increase the penetration and diffusion ability of lithium ions at the negative electrode interface, thereby increasing the low temperature and rate performance of the lithium-ion battery.

[0088] However, electrolytes containing only fluorinated cyclic carbonate compounds do not resolve the lithium deposition problem in the late stages of cycling or after long cycles at low temperatures. Furthermore, without the addition of nitrogen-containing heterocyclic compounds containing sulfonate or sulfone groups, direct contact between the cathode interface and the electrolyte catalyzes their decomposition, resulting in significant degradation of cycling performance at both room and high temperatures.

[0089] 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 a nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group; The nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group is selected from at least one of the compounds shown in Formula 1: In formula 1, X is -O- or -N(R2)-; R1 is halogen, substituted or unsubstituted alkyl. If substituted, the substituent is halogen or alkyl; R2 is a substituted or unsubstituted aryl group, a substituted or unsubstituted alkyl group. If substituted, the substituent is a halogen or an alkyl group.

2. The electrolyte according to claim 1, characterized in that The electrolyte further includes a fluorinated cyclic carbonate compound.

3. The electrolyte according to claim 1, characterized in that R1 is halogen, substituted or unsubstituted C 1-12 Alkyl, if substituted, the substituent is halogen, C 1-12 alkyl; R2 is substituted or unsubstituted C 6-20 Aryl, substituted or unsubstituted C 1-12 Alkyl, if substituted, the substituent is halogen, C 1-12 alkyl.

4. The electrolyte according to claim 3, characterized in that The nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group is selected from at least one of Compounds A to F:

5. The electrolyte according to claim 1, characterized in that The mass of the nitrogen-containing heterocyclic compound containing sulfonate groups or sulfone groups accounts for 0.1 to 0.5 wt % of the total mass of the electrolyte.

6. The electrolyte according to claim 2, characterized in that The fluorinated cyclic carbonate compound is selected from at least one of the compounds shown in Formula 2: In formula 2, R3 and R4 are the same or different and are independently selected from H, F, substituted or unsubstituted alkyl, and contain at least one F atom. If substituted, the substituent is F or alkyl.

7. The electrolyte according to claim 2, characterized in that The mass of the fluorinated cyclic carbonate compound accounts for 1 wt% to 10 wt% of the total mass of the electrolyte.

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

9. The battery according to claim 8, 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。

Images