Electrolyte and use thereof

Abstract

The present application provides an electrolyte and a use thereof. The electrolyte comprises fluoroethylene carbonate and a boric acid ester compound. The electrolyte is used in a battery, and can facilitate the forming of a high-quality SEI film on the surface of a negative electrode, and effectively inhibit the side reaction of a silicon-based battery, so that the battery impedance is reduced, and the high-temperature cycle and the high-temperature storage performance of the battery are improved.

Description

An electrolyte and its application

[0001] This application claims priority to a Chinese patent application filed with the Patent Office of China on November 30, 2023, with application number 202311626975.0 and application name “An Electrolyte and Its Application,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present application relates to an electrolyte and its application, belonging to the field of energy technology. Background Art

[0003] With technological advancements and the diversification of energy demands, traditional energy consumption is accelerating, prompting countries to accelerate their strategic deployment of new energy technologies. Power batteries, in particular, are experiencing a surge in popularity alongside the development of new energy vehicles, while energy storage batteries are also gaining momentum alongside the growth of clean energy. Since 2017, competition in the new energy vehicle industry has intensified, with power battery companies continuously developing and updating their products in an effort to find chemical power systems that are more adaptable to the market and meet user demands for high energy density and long driving range, with the goal of fully replacing traditional energy-powered passenger cars and buses.

[0004] Lithium-ion batteries are one of the important products in new energy technology. Traditional lithium-ion batteries use graphite to prepare the negative electrode sheet, and the specific capacity of graphite is 372mAh g -1 , which is difficult to meet the higher specific energy requirements of lithium-ion batteries. Therefore, researchers at home and abroad have gradually turned their attention to silicon anode materials with high specific capacity. However, although silicon anode materials can improve the energy density of batteries to a certain extent, they are prone to huge volume expansion during the battery cycle, which will cause the interface film between the anode sheet and the electrolyte to be continuously damaged, causing the electrolyte to continue to decompose, and ultimately deteriorating the battery performance.

[0005] In order to solve the problem of battery performance deterioration caused by damage to the interface film between the negative electrode sheet and the electrolyte during the cycle of batteries containing silicon negative electrode materials, researchers have proposed that a new electrolyte additive can be developed to build a stable interface film on the surface of the negative electrode sheet to reduce the negative effects caused by the expansion of the silicon negative electrode material. For example, fluoroethylene carbonate (FEC) is used as an electrolyte additive and added to the electrolyte to form a stable interface film on the surface of the negative electrode sheet, thereby effectively reducing the capacity loss caused by the silicon negative electrode material and reducing the interface impedance between the negative electrode sheet and the electrolyte. However, FEC will produce gas at high temperatures, which can cause battery failure or even explosion.

[0006] Summary of the Invention

[0007] The present application provides an electrolyte, which, when used in a battery, helps to form a high-quality SEI film on the surface of the negative electrode and effectively inhibits the side reactions of the silicon-based battery, thereby reducing the battery impedance and improving the high-temperature cycle and high-temperature storage performance of the battery.

[0008] The present application also provides a battery containing the above-mentioned electrolyte, so that the battery has relatively excellent electrochemical performance.

[0009] The present application provides an electrolyte solution, which includes fluoroethylene carbonate and borate compounds.

[0010] The electrolyte as described above, wherein the borate compound has a structural formula as shown in any one of Formulas 1 to 4;

[0011] In formula 1 to formula 4, R1, R2, R3, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 Each is independently selected from a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C2-C30 alkenyl group, and a substituted or unsubstituted C1-C30 silyl group;

[0012] In Formula 2, R4 and R5 are each independently selected from a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C2-C30 alkenyl group, a substituted or unsubstituted C1-C30 silyl group, and / or R4 and R5 are connected to form a ring.

[0013] The electrolyte as described above, wherein R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 The substituents are selected from at least one of substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C2-C30 alkenyl, carbonyl and halogen.

[0014] The electrolyte as described above, wherein the borate compound is selected from the compounds shown in the following structures:

[0015] In the electrolyte as described above, the mass percentage of the borate ester compound is 0.1%-2% based on the total mass of the electrolyte.

[0016] The electrolyte as described above, wherein the mass percentage of the fluoroethylene carbonate is 1%-15% based on the total mass of the electrolyte.

[0017] In the electrolyte as described above, based on the total mass of the electrolyte, the mass percentage of the borate ester compound is 0.1-1%, and the mass percentage of the fluoroethylene carbonate is 5-10%.

[0018] The electrolyte as described above, wherein the electrolyte further comprises a solvent, and the mass percentage of the solvent is 10-80% based on the total mass of the electrolyte; and / or,

[0019] The electrolyte further comprises other additives, and the mass percentage of the other additives is 0.5-5% based on the total mass of the electrolyte;

[0020] The other additives are selected from at least one of vinylene carbonate, vinyl ethylene carbonate, ethylene sulfate, 1,3-propane sultone, 1,3-propylene sultone, vinyl sulfite and tris(trimethylsilyl)borate.

[0021] The electrolyte as described above, wherein the electrolyte further comprises lithium salt, and the mass percentage of the lithium salt is 12%-18% based on the total mass of the electrolyte.

[0022] The present application provides a battery, which includes the electrolyte as described above.

[0023] The electrolyte of the present application has a simple composition. When used in a battery, such as a secondary battery, the electrolyte helps to form a denser and more stable SEI film on the negative electrode surface of the secondary battery, thereby protecting the electrode and improving the performance of the secondary battery.

[0024] Since the battery of the present application includes the aforementioned electrolyte, the negative electrode surface has a dense and stable SEI film to further avoid contact damage between the electrode and the electrolyte. Therefore, the electrochemical device of the present application has more excellent electrochemical performance, such as high-temperature cycling and high-temperature storage performance. DETAILED DESCRIPTION

[0025] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0026] A first aspect of the present application provides an electrolyte comprising fluoroethylene carbonate (FEC) and a borate compound.

[0027] The electrolyte solution comprising fluoroethylene carbonate and borate compounds disclosed herein can significantly improve the electrochemical performance of batteries when used in them. The inventors have analyzed this phenomenon and believe that the reason may be that the boron atom in the borate compound is an electron-deficient atom. In the electrolyte system, it can effectively complex the free fluoride ions generated by the decomposition of FEC, thereby cutting off the path for FEC side reactions and effectively suppressing gas generation. Furthermore, the borate ester in the borate compound can react with trace amounts of lithium salts in the electrolyte to form a low-impedance component that participates in the formation of an electrode / electrolyte interface film, lowering the diffusion energy barrier for lithium ions. This allows for rapid lithium ion insertion and extraction, reduces lithium dendrite formation, and improves the cycle life of lithium-ion batteries. Furthermore, the low-impedance interface film facilitates rapid lithium ion insertion and extraction, and also improves the battery's performance at low temperatures. It is worth mentioning that the boron atom is a common central atom that can connect to various active groups in the electrolyte, further enhancing the film formation of FEC and thus improving the battery's electrochemical performance.

[0028] In some embodiments of the present application, the structural formula of the borate ester compound is shown in any one of Formula 1 to Formula 4;

[0029] In formula 1 to formula 4, R1, R2, R3, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 Each is independently selected from a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C2-C30 alkenyl group, and a substituted or unsubstituted C1-C30 silyl group;

[0030] In Formula 2, R4 and R5 are each independently selected from a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C2-C30 alkenyl group, a substituted or unsubstituted C1-C30 silyl group, and / or R4 and R5 are connected to form a ring.

[0031] Specifically, in Formula 1 to Formula 4, R1, R2, R3, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13Each is independently selected from a substituted or unsubstituted C1-C30 alkyl group (for example, a substituted straight-chain alkyl group, a substituted branched-chain alkyl group, a substituted cycloalkyl group, an unsubstituted straight-chain alkyl group, an unsubstituted branched-chain alkyl group, or an unsubstituted cycloalkyl group), a substituted or unsubstituted C2-C30 alkenyl group (for example, a substituted branched-chain alkenyl group, a substituted straight-chain alkenyl group, a substituted cycloalkenyl group, an unsubstituted straight-chain alkenyl group, an unsubstituted branched-chain alkenyl group, or an unsubstituted cycloalkenyl group), and a substituted or unsubstituted C1-C30 silyl group (for example, a substituted straight-chain silyl group, a substituted straight-chain silyl group, a substituted cyclic silyl group, an unsubstituted branched-chain silyl group, an unsubstituted straight-chain silyl group, or an unsubstituted cyclic silyl group).

[0032] In Formula 2, R4 and R5 are each independently selected from a substituted or unsubstituted C1-C30 alkyl group (for example, a substituted straight-chain alkyl group, a substituted branched-chain alkyl group, a substituted cycloalkyl group, an unsubstituted straight-chain alkyl group, an unsubstituted branched-chain alkyl group, or an unsubstituted cycloalkyl group), a substituted or unsubstituted C2-C30 alkenyl group (for example, a substituted branched-chain alkenyl group, a substituted straight-chain alkenyl group, a substituted cycloalkenyl group, an unsubstituted straight-chain alkenyl group, an unsubstituted branched-chain alkenyl group, or an unsubstituted cycloalkenyl group), or a substituted or unsubstituted C1-C30 silyl group (for example, a substituted straight-chain silyl group, a substituted straight-chain silyl group, a substituted cyclic silyl group, an unsubstituted branched-chain silyl group, an unsubstituted straight-chain silyl group, or an unsubstituted cyclic silyl group);

[0033] Or, R4 and R5 are directly connected to form a ring;

[0034] Alternatively, R4 and R5 are a cyclic structure formed by connecting any two of the above groups.

[0035] This application is for R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 The substituents are not particularly limited, and R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 The substituents may be substituents commonly used in the art. For example, the substituents may be at least one of substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C2-C30 alkenyl, carbonyl, halogen, substituted or unsubstituted C6-C60 aryl, amino, ester, and cyano.

[0036] The inventors discovered in their research that when the borate ester compound has the above-mentioned structure, the electrochemical performance of the battery can be further improved. In particular, when the borate ester compound contains a silane group, the silane group can further eliminate trace water in the electrolyte and further enhance the ability to cut off side reactions. Furthermore, when the borate ester compound contains a silane group including an unsaturated bond (for example, an unsaturated bond-substituted silane group), the potential for electrolyte polymerization to form a film can be improved. When the borate ester compound contains a Si-O bond, the high-temperature tolerance of the interface film can be further improved, ultimately enhancing the high-temperature performance of the battery.

[0037] When the borate compound contains an unsaturated bond (for example, a substituted or unsubstituted alkenyl group), the film-forming ability of the borate compound can be improved, so that the borate compound can directly participate in the construction of the interfacial film. The central atom B of the borate compound can adhere to the electrode surface, better complexing the free F ions in the electrolyte, reducing the attack of HF acid on the interfacial film and battery materials, and improving the electrochemical performance of the battery.

[0038] When borate compounds contain fluoroalkyl groups, the CF bond in the fluoroalkyl groups has excellent stability, and it is not easy to generate highly active fluoride ions in the electrolyte, which can avoid side reactions of fluoride ions. At the same time, the fluoroalkyl groups are very stable and can be considered as an excellent inert component. When borate compounds participate in the construction of the interfacial film, they can be embedded in the interfacial film, thereby increasing the inertness of the interfacial film, reducing the reaction sites of the interfacial film, and thus improving the stability of the interfacial film.

[0039] Compared to Formulas 1-3, the double-boron structure of Formula 4 has two central boron atoms, which are better at adsorbing fluoride ions, further reducing the negative effects of fluoride ions. In addition, the double-boron structure can carry more functional groups, which is beneficial for its participation in the construction of the interfacial film.

[0040] In some embodiments of the present application, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 The substituents of R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13The substituents are selected from at least one of substituted or unsubstituted C1-C30 alkyl (for example, substituted straight-chain alkyl, substituted branched-chain alkyl, substituted cycloalkyl, unsubstituted straight-chain alkyl, unsubstituted branched-chain alkyl, and unsubstituted cycloalkyl), substituted or unsubstituted C2-C30 alkenyl (for example, substituted branched-chain alkenyl, substituted straight-chain alkenyl, substituted cycloalkenyl, unsubstituted straight-chain alkenyl, unsubstituted branched alkenyl, and unsubstituted cycloalkenyl), carbonyl, and halogen (for example, F, Cl, Br, and I).

[0041] Illustratively, the borate ester compound is selected from the compounds shown in the following structures;

[0042] It is understood that the content of borate compounds and fluoroethylene carbonate in the electrolyte has a significant impact on the performance of the electrolyte. Therefore, the present application can further select the content of borate compounds and fluoroethylene carbonate in the electrolyte to improve the overall performance of the electrolyte. For example, the mass percentage of the borate compounds is 0.1%-2% based on the total mass of the electrolyte; and / or the mass percentage of fluoroethylene carbonate is 1%-15% based on the total mass of the electrolyte.

[0043] The inventors also found in their research that when the mass percentage of borate compounds is 0.1-1% and the mass percentage of fluoroethylene carbonate is 5-10% based on the total mass of the electrolyte, the borate compounds can better match the fluoroethylene carbonate, further improving the overall performance of the electrolyte and thus improving the overall performance of the battery.

[0044] In some embodiments of the present application, the electrolyte further includes a solvent, and the mass percentage of the solvent is 10-80% based on the total mass of the electrolyte.

[0045] The present application does not particularly limit the solvent, and can be a solvent commonly used in the art. For example, the solvent can be at least one of propylene carbonate, ethyl methyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, fluoroethylene carbonate, γ-butyrolactone, sulfolane, 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.

[0046] The electrolyte also includes other additives. Based on the total mass of the electrolyte, the mass percentage of the other additives is 0.5-5%.

[0047] The present application does not particularly limit other additives, and they may be electrolyte additives commonly used in the art. For example, the electrolyte additive may be at least one of vinylene carbonate (VC), vinyl ethylene carbonate (VEC), ethylene sulfate (DTD), 1,3-propane sultone (PS), 1,3-propylene sultone (PST), vinyl sulfite (ES), and tris(trimethylsilyl)borate (TMSB).

[0048] When the electrolyte further includes the above-mentioned specific content of the solvent and / or specific content of other additives, the overall performance of the electrolyte can be further improved, thereby improving the overall performance of the battery.

[0049] In some embodiments of the present application, the electrolyte further comprises a lithium salt, and the mass percentage of the lithium salt is 12%-18% based on the total mass of the electrolyte. Further, the mass percentage of the lithium salt is greater than 12.5%.

[0050] The present application does not particularly limit the lithium salt, and may be any lithium salt commonly used in the art. For example, the lithium salt may be at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(oxalatoborate), and lithium difluorooxalatoborate.

[0051] It can be understood that lithium salt is an important component in the electrolyte. By further limiting the content of lithium salt in the electrolyte, the present application can give full play to the role of lithium salt, improve the comprehensive performance of the electrolyte, and thus improve the comprehensive performance of the battery.

[0052] A second aspect of the present application is a battery, comprising the electrolyte of the first aspect.

[0053] It can be understood that the battery of the present application also includes a positive electrode sheet, a negative electrode sheet, a separator and an outer packaging.

[0054] The present application does not specifically limit the positive electrode sheet, and it can be a common positive electrode sheet in the art. In some embodiments, the positive electrode active material in the positive electrode sheet can be at least one of lithium cobalt oxide, lithium iron phosphate, and a ternary material. Furthermore, the molar percentage of the Ni element or the Mn element in the positive electrode active material is greater than 65%. The compacted density of the positive electrode active layer of the positive electrode sheet can be 1-5 g / cm 3 .

[0055] The present application does not specifically limit the negative electrode sheet, and it can be a common negative electrode sheet in the art. In some embodiments, the negative electrode active material in the negative electrode sheet can be selected from at least one of artificial graphite, natural graphite, lithium titanate, silicon, silicon carbon, silicon oxide, and silicon metal compound. Furthermore, the negative electrode active material can be silicon carbon and / or silicon oxide. The compacted density of the negative electrode active material of the negative electrode sheet can be 1-4 g / cm3 .

[0056] During specific application, the electrolyte will form a stable SEI film on the surface of the negative electrode, and the electrolyte is not easy to produce gas at high temperatures. Therefore, the battery containing the electrolyte of the present application can have excellent room temperature cycle performance, high temperature cycle performance and high temperature storage performance.

[0057] The electrolyte of the present application and its applications are described in detail below through specific examples.

[0058] Example 1

[0059] The battery of this embodiment is prepared by a method comprising the following steps:

[0060] (1) Preparation of positive electrode sheet

[0061] The positive electrode active material NCM811, the binder polyvinylidene fluoride (PVDF), and the conductive agent acetylene black were mixed in a mass ratio of 96.5:2:1.5, and N-methylpyrrolidone (NMP) was added. The mixture was stirred in a vacuum mixer until the raw materials were mixed into a positive electrode slurry with uniform fluidity;

[0062] The positive electrode slurry was evenly coated on both surfaces of a 7μm thick aluminum foil, baked in an oven with five different temperature gradients, and then dried in an oven at 120°C for 8 hours. The positive electrode active layer was then roller-pressed to control the compaction density of the positive electrode active layer to 3.5g / cm 3 , cut to obtain the positive electrode sheet.

[0063] (2) Preparation of negative electrode sheet

[0064] The negative electrode active material carbon silicon material @ graphite (the mass percentage of carbon silicon material is 10%), the thickener sodium carboxymethyl cellulose (CMC-Na), the binder styrene butadiene rubber, the conductive agent acetylene black, and the conductive agent single-walled carbon nanotube (SWCNT) were mixed in a mass ratio of 95.9:1:2:1:0.1, and deionized water was added to obtain a negative electrode slurry under the action of a vacuum mixer;

[0065] The negative electrode slurry was evenly coated on both surfaces of a 6 μm thick copper foil, dried (temperature: 85 ° C, time: 5 h), and rolled to control the compaction density of the negative electrode active layer to 1.65 g / cm 3 , die-cut to obtain the negative electrode sheet.

[0066] (3) Preparation of electrolyte

[0067] In an argon-filled glove box (moisture <10 ppm, oxygen <1 ppm), ethylene carbonate (EC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and propylene carbonate (PC) were mixed at a mass ratio of 1.5:1.5:5:2 to obtain a mixed solution. Thoroughly dried lithium salts, FEC, and borate compounds were quickly added to the mixed solution. See Table 1 for details.

[0068] (4) Preparation of lithium-ion batteries

[0069] The positive electrode sheet of step (1), the separator, and the negative electrode sheet of step (2) are stacked in sequence, and then wound to obtain a bare battery cell without liquid injection;

[0070] The bare cell is placed in an outer packaging foil, the electrolyte of step (3) is injected into the dried bare cell, and the desired lithium-ion battery is obtained through vacuum packaging, standing, forming, shaping, and sorting.

[0071] The diaphragm is a coated polyethylene diaphragm with a thickness of 8 μm.

[0072] Example 2-52 and Comparative Example 1-2

[0073] The composition of the electrolyte of Example 2-52 is basically the same as that of Example 1, and the differences are shown in Table 1.

[0074] The electrolyte in Example 1 was replaced with the electrolytes of Example 2-52 and Comparative Example 1-2, respectively, to obtain lithium ion batteries of Example 2-52 and Comparative Example 1-2, respectively.

[0075] Table 1

[0076] In Table 1, compound C is as follows:

[0077] Performance Testing

[0078] The following performance tests were performed on the batteries in the examples and comparative examples, and the test results are shown in Table 2.

[0079] 1) Normal temperature cycle performance test

[0080] The battery was charged at room temperature (25°C) at a constant current of 1C to 4.2V, and then at a constant voltage of 4.2V to a cutoff current of 0.05C. The battery was then discharged at 1C to 2.75V. The charge and discharge were repeated for 600 cycles. The discharge capacity of the 600th cycle was recorded and divided by the discharge capacity of the first cycle to obtain the capacity retention rate.

[0081] 2) High temperature cycle performance test

[0082] The battery was charged at a high temperature of 45°C at a constant current of 1C to 4.2V, and then charged at a constant voltage of 4.2V to a cutoff current of 0.05C. The battery was then discharged at 1C to 2.75V. The charge and discharge were repeated for 200 cycles. The discharge capacity of the 200th cycle was recorded and divided by the discharge capacity of the first cycle to obtain the capacity retention rate.

[0083] 3) DCIR test

[0084] The divided battery was charged to 4.2V at 1C at room temperature, left for 5 minutes, then discharged at 1C for 30 minutes, left for 1 hour, and then discharged at 2C for 10 seconds. The DCIR of the battery at 50% SOC was calculated.

[0085] 4) High temperature storage performance test

[0086] The battery was charged to 4.2V at a constant current of 1C at room temperature of 25°C, charged to a cut-off current of 0.05C at a constant voltage of 4.2V, and then discharged at a constant current of 0.5C. The discharge capacity was recorded as C1. At room temperature of 25°C, the battery was charged to 4.2V at a constant current of 1C, charged to a cut-off current of 0.05C at a constant voltage of 4.42, and the battery thickness was measured and recorded as h1 (the battery thickness before storage at 60°C). The battery was then transferred to a high temperature of 60°C and left for 7 days. The battery thickness was measured again and recorded as h2 (the battery thickness after storage at 60°C for 7 days). The battery was then discharged at a constant current of 0.5C, and the discharge capacity was recorded as C2. The capacity retention rate at 60°C = C2 / C1*100%;

[0087] The DCIR of the battery after being stored at 60°C for 7 days was tested using the method in 3).

[0088] Table 2

[0089] As shown in Table 2, the battery in the embodiment of the present application has better room temperature cycle performance, high temperature cycle performance, high temperature storage performance and lower impedance;

[0090] Furthermore, it can be seen from Examples 9 and 47-48, and from Examples 6, 53-54, and 55-56 that when the mass percentage of the borate ester compound in the electrolyte is 0.1%-2%, the obtained battery has more excellent comprehensive performance;

[0091] From Examples 4-6 and 7-8, Examples 9-12 and 13-15, Examples 19, 21, 23 and 20, 22, Examples 26-28 and 29-30, Examples 31, 33 and 32, 34, 35, Examples 36-38 and 39-40, 44, Example 9 and 45, 46, Examples 6, 53 and 54, 57, 58, it can be seen that when the mass percentage of the borate ester compound in the electrolyte is 0.1-1% and the mass percentage of fluoroethylene carbonate is 5-10%, the obtained battery has more excellent comprehensive performance;

[0092] It can be seen from Example 6 and Example 50, and Example 11 and Example 51 that when the electrolyte also includes other additives, the obtained battery has better comprehensive performance.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An electrolyte, wherein Including fluoroethylene carbonate and borate compounds.

2. The electrolyte according to claim 1, wherein The structural formula of the borate ester compound is shown in any one of Formula 1 to Formula 4; In Formula 1 to Formula 4, R1, R2, R3, R6, R7, R8, R9, R 10 , R 11 , R 12 , R 13 Each is independently selected from a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C2-C30 alkenyl group, and a substituted or unsubstituted C1-C30 silyl group; In Formula 2, R4 and R5 are each independently selected from a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C2-C30 alkenyl group, a substituted or unsubstituted C1-C30 silyl group, and / or R4 and R5 are connected to form a ring.

3. The electrolyte according to claim 1 or 2, wherein R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 , R 11 , R 12 , R 13 The substituents are selected from at least one of substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C2-C30 alkenyl, carbonyl and halogen.

4. The electrolyte according to any one of claims 1 to 3, wherein The borate ester compound is selected from the compounds shown in the following structures; 5. The electrolyte according to any one of claims 1 to 4, wherein: Based on the total mass of the electrolyte, the mass percentage of the borate ester compound is 0.1%-2%.

6. The electrolyte according to any one of claims 1 to 5, wherein Based on the total mass of the electrolyte, the mass percentage of the fluoroethylene carbonate is 1%-15%.

7. The electrolyte according to claim 5 or 6, wherein Based on the total mass of the electrolyte, the mass percentage of the borate ester compound is 0.1-1%, and the mass percentage of the fluoroethylene carbonate is 5-10%.

8. The electrolyte according to any one of claims 1 to 7, wherein: The electrolyte further comprises a solvent, and the mass percentage of the solvent is 10-80% based on the total mass of the electrolyte; and / or, The electrolyte further comprises other additives, and the mass percentage of the other additives is 0.5-5% based on the total mass of the electrolyte; Wherein, the solvent comprises at least one 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; The other additives are selected from at least one of vinylene carbonate, vinyl ethylene carbonate, ethylene sulfate, 1,3-propane sultone, 1,3-propene sultone, vinyl sulfite and tris(trimethylsilyl)borate.

9. The electrolyte according to any one of claims 1 to 8, wherein: The electrolyte further comprises lithium salt, and based on the total mass of the electrolyte, the mass percentage of the lithium salt is 12%-18%.

10. A battery, wherein: The electrolyte comprising the electrolyte according to any one of claims 1 to 9.

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