Electrolyte and use thereof

Abstract

The present application provides an electrolyte and its application, the electrolyte includes silane of formula 1, in formula 1, X is selected from O or N;At least one of R1, R2, R3, R4, R5, R6 is selected from at least one of substituted or unsubstituted C2-C30 alkenyl, substituted or unsubstituted C2-C30 alkynyl;And the rest are each independently selected from at least one of hydrogen, halogen, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C1-C30 alkoxy, substituted or unsubstituted C6-C60 aryl.The electrolyte is used in battery, it is helpful to form high quality SEI film on the surface of negative electrode, to improve the electrochemical performance of battery.

Description

TECHNICAL FIELD

[0001] The present application relates to an electrolyte and its application, and belongs to the technical field of energy. BACKGROUND

[0002] With the progress of science and technology and the diversification of energy demand, traditional energy is accelerating consumption, and countries are constantly accelerating the strategic deployment of new energy technology. Among them, power batteries are rising with the development of new energy vehicles, and energy storage batteries are also emerging with the development of clean energy. Since 2017, the competition in the new energy vehicle industry has become increasingly fierce, and various power battery companies have continuously developed new products in order to find a more market-oriented chemical power system to meet users' requirements for high specific energy and endurance, in the hope of replacing traditional energy in all aspects of passenger cars and buses.

[0003] Lithium ion batteries are one of the important products in new energy technology. Traditional lithium ion batteries use graphite to prepare negative electrode sheets, and the specific capacity of graphite is 372mAh g -1 , which has been difficult to meet the higher specific energy requirements of lithium ion batteries. Therefore, domestic and foreign researchers have gradually turned their attention to silicon negative electrode materials with high specific capacity. However, although silicon negative electrode materials can improve the energy density of the battery to some extent, silicon negative electrode materials are prone to large volume expansion during the cycle process of the battery, which will cause the interface film of the negative electrode sheet and the electrolyte to be continuously destroyed, causing the electrolyte to continuously decompose, and ultimately deteriorating the performance of the battery. SUMMARY

[0004] The present application provides an electrolyte, which is used in a battery, helps to form a high-quality SEI film on the surface of the negative electrode, and effectively inhibits the high-temperature gas production problem of silicon-based batteries, thereby reducing the impedance of the battery and improving the high-temperature cycle and high-temperature storage performance of the battery.

[0005] The present application also provides a battery containing the above-mentioned electrolyte, and therefore the battery has relatively excellent electrochemical performance.

[0006] The present application provides an electrolyte, wherein it comprises a silane represented by Formula 1;

[0007]

[0008] In Formula 1, X is selected from O or N;

[0009] at least one of R1, R2, R3, R4, R5, and R6 is selected from at least one of a substituted or unsubstituted C2-C30 alkenyl group and a substituted or unsubstituted C2-C30 alkynyl group; and the rest are each independently selected from at least one of hydrogen, a halogen, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, and a substituted or unsubstituted C6-C60 aryl group.

[0010] The electrolyte as described above, wherein the silane comprises Si-O bond; and / or,

[0011] The silane has symmetrical structure.

[0012] The electrolyte as described above, wherein the silane is selected from the compounds shown in the following structures:

[0013]

[0014]

[0015] The electrolyte as described above, wherein the mass percentage of the silane is 0.5%-2% based on the total mass of the electrolyte.

[0016] The electrolyte as described above, wherein the electrolyte further comprises fluoroethylene carbonate.

[0017] The electrolyte as described above, wherein the mass percentage of the fluoroethylene carbonate is 1%-20% based on the total mass of the electrolyte.

[0018] The electrolyte as described above, wherein the electrolyte further comprises isocyanate compound.

[0019] The electrolyte as described above, wherein the mass percentage of the isocyanate compound is 0.1%-0.5% based on the total mass of the electrolyte.

[0020] The electrolyte as described above, wherein the electrolyte further comprises lithium salt, and the mass percentage of the lithium salt is 12.5%-18% based on the total mass of the electrolyte.

[0021] The present application provides a battery, wherein the electrolyte as described above is included.

[0022] The electrolyte of the present application has simple composition, and when used in a battery, such as a secondary battery, it helps to form a more compact and stable SEI film on the surface of the negative electrode of the secondary battery, thereby protecting the electrode and further improving the performance of the secondary battery.

[0023] The battery of the present application has a compact and stable SEI film on the surface of the negative electrode due to the inclusion of the aforementioned electrolyte, thereby further avoiding the damage caused by the contact between the electrode and the electrolyte, and thus the electrochemical device of the present application has more excellent electrochemical performance, such as high-temperature cycling and high-temperature storage performance. DETAILED DESCRIPTION

[0024] In order to make the objects, technical solutions, and advantages of the present application clearer, the following will be combined with embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0025] The first aspect of the present application provides an electrolyte solution comprising a silane represented by Formula 1.

[0026]

[0027] In Formula 1, X is selected from O or N;

[0028] at least one of R1, R2, R3, R4, R5, and R6 is selected from at least one of a substituted or unsubstituted C2-C30 alkenyl group, a substituted or unsubstituted C2-C30 alkynyl group; and the rest are each independently selected from at least one of hydrogen, a halogen, a substituted or unsubstituted C2-C30 alkyl group, a substituted or unsubstituted C2-C30 alkoxy group, and a substituted or unsubstituted C6-C60 aryl group.

[0029] Specifically in Formula 1, at least one of R1, R2, R3, R4, R5, and R6 is selected from at least one of a substituted or unsubstituted alkenyl group (a straight-chain alkenyl group, a cyclic alkenyl group (for example, a cyclopentadiene containing or not containing a heteroatom)), and a substituted or unsubstituted alkynyl group (a straight-chain alkynyl group, a cyclic alkynyl group).

[0030] Further, the rest (not selected from at least one of a substituted or unsubstituted alkenyl group and a substituted or unsubstituted alkynyl group) of R1, R2, R3, R4, R5, and R6 are each independently selected from at least one of hydrogen, a halogen (for example, F, Cl, Br, I), a substituted or unsubstituted alkyl group (-C n H 2n-1 , n is a positive integer of 1-30), a substituted or unsubstituted alkoxy group (-C n H 2n-2 O, n is a positive integer, for example, can be a positive integer of 1-30), and a substituted or unsubstituted aryl group.

[0031] The present application does not limit the types of substituents of the alkenyl group, the alkynyl group, the alkyl group, the alkoxy group, and the aryl group, and can be a substituent commonly used in the art, for example, can be at least one of a halogen, a cyano group, an ester group, a nitro group, an amino group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted alkoxy group, an isocyano group, an isocyanate group, and a substituted or unsubstituted aryl group.

[0032] The electrolyte of the present application, due to the silane of formula 1, the alkenyl or alkynyl group is easy to polymerize or cross-link into a film in the charging and discharging process of the battery, which helps to form a stable SEI film on the surface of the negative electrode, and improves the electrochemical performance of the battery. When X is selected from O, the silane contains Si-O-Si bond, Si-O-Si bond has excellent thermal stability, which is beneficial to adhere to the surface of the negative electrode as the skeleton of the polymer, and maintain the stability of the interface film; when X is selected from N, the Si-N bond in Si-N-Si system is easy to break to form the corresponding silanol, and then two molecules of silanol condense to form disiloxane. At the same time, the silane containing Si-O-Si and the silane containing Si-N-Si not only can construct a stable interface film, but also have a certain acid reaction ability, which can be used to remove HF acid in the electrolyte, reduce the side reaction of the battery interface, and improve the electrochemical performance of the battery.

[0033] It is worth mentioning that when the silane contains Si-O bond, the Si-O bond has higher bond energy, which not only helps to further improve the high temperature resistance of the electrolyte, but also can form a more high temperature resistant SEI film in the charging and discharging process of the battery, and further improve the high temperature performance of the battery.

[0034] In some embodiments of the present application, when the silane has a symmetrical structure (axial symmetry or central symmetry), not only the preparation cost of the silane can be reduced, but also the large-scale application of the silane is promoted. In addition, the symmetrical structure of the silane molecule has lower activity, which is convenient for storage and is not easy to have side reactions during storage, which helps to improve the electrochemical performance of the battery.

[0035] Exemplarily, the silane is selected from the compounds shown in the following structures:

[0036]

[0037]

[0038] Because the silane can form a stable SEI film on the surface of the negative electrode in the charging and discharging process of the battery, which improves the electrochemical performance of the battery, it can be understood that the content of silane in the electrolyte has a crucial influence on the performance of the battery. Therefore, the present application can further select the content of silane in the electrolyte in order to improve the comprehensive performance of the battery. Exemplarily, in some embodiments of the present application, the mass percentage content of silane is 0.5%-2% based on the total mass of the electrolyte, which can better inhibit the gas production of the battery without increasing the impedance of the battery. Further, the mass percentage content of silane is 0.1%-1% based on the total mass of the electrolyte.

[0039] In some embodiments of the present application, the electrolyte further comprises fluoroethylene carbonate.

[0040] In the present application, when the electrolyte further comprises fluoroethylene carbonate (FEC), the FEC can match the silane in the present application, and a more stable and compact SEI film can be formed during the charging and discharging process of the battery, thereby protecting the negative electrode and improving the electrochemical performance of the battery. Meanwhile, the silane in the present application can also overcome the defect of high-temperature gas production of FEC, thereby further improving the high-temperature performance of the battery.

[0041] Further, when the mass percentage of FEC is 1-20% based on the total mass of the electrolyte, the FEC can match the silane more perfectly, thereby improving the electrochemical performance of the battery. Further, the mass percentage of FEC is 5%-10% based on the total mass of the electrolyte.

[0042] In some embodiments of the present application, the electrolyte further comprises an isocyanate compound.

[0043] The isocyanate compound in the present application is not particularly limited and can be an isocyanate compound commonly used in the art. For example, the isocyanate compound can be at least one selected from the group consisting of hexamethyl diisocyanate (B1), p-phenylene diisocyanate (B2), methyl-silane triisocyanate, 1,4-diisocyanato-2-methylbenzene (B3), γ-isocyanatopropyl trimethoxysilane (B4), γ-isocyanatopropyl triethoxysilane, γ-isocyanatopropyl methyl dimethoxysilane, isocyanatopropyl methyl diethoxysilane, γ-isocyanatopropyl dimethyl methoxysilane, α-isocyanatomethyl trimethoxysilane, α-isocyanatomethyl triethoxysilane, and α-isocyanatomethyl dimethoxysilane.

[0044] When the electrolyte further comprises an isocyanate compound in the present application, the isocyanate compound, FEC, and silane can synergistically generate an interface film with more excellent stability, thereby improving the high-temperature storage performance and high-temperature cycle performance of the battery. For example, the isocyanate compound can avoid side reactions of the silane and avoid the generation of by-product trimethylsilyl fluoride (TMSF), thereby enabling the silane to fully play a role in inhibiting gas production. Moreover, during the charging and discharging process of the battery, the isocyanate compound can generate polyurethane, which not only has excellent elasticity but also has outstanding heat retention performance, thereby effectively inhibiting the expansion of silicon materials in the negative electrode sheet and the intrusion of external high temperature on the generated interface film, and improving the high-temperature storage performance and high-temperature cycle performance of the battery.

[0045] Further, when the isocyanate compound is at least one selected from the group consisting of hexamethyl diisocyanate, p-phenylene diisocyanate, and 1,4-diisocyanato-2-methylbenzene, the isocyanate compound, FEC, and silane can further improve the electrochemical performance of the battery.

[0046] In some embodiments of the present application, when the mass percentage of the isocyanate compound is 0.1%-0.5% based on the total mass of the electrolyte, the isocyanate compound can sufficiently play its role in reducing the interfacial impedance and improving the electrochemical performance of the battery.

[0047] In some embodiments of the present application, the electrolyte further comprises a lithium salt, and the mass percentage of the lithium salt is 12.5%-18% based on the total mass of the electrolyte.

[0048] The lithium salt in the present application is not particularly limited and can be a lithium salt commonly used in the art. Illustratively, the lithium salt can be selected from at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium tetrafluoroborate, lithium bisoxalate borate, lithium difluoro oxalate phosphate, and lithium tetrafluoro oxalate phosphate.

[0049] In the present application, when the content of the lithium salt is in the above range, the lithium ions in the lithium salt can preferentially participate in the construction of the interfacial film, and the anions in the lithium salt can also participate in the construction of the interfacial film. Excessive lithium salt can make the interfacial film rich in lithium-containing compounds during the construction of the interfacial film, reduce the interfacial impedance of the interfacial film, and improve the low-temperature performance of the battery. In addition, the excessive lithium salt also has a self-sacrifice effect, which reduces the loss of active lithium in the positive active material of the battery, thereby improving the initial efficiency of the battery.

[0050] The mass percentage of the lithium salt is 15%-18% based on the total mass of the electrolyte.

[0051] In some embodiments, when the lithium salt is a mixed lithium salt comprising lithium hexafluorophosphate, lithium bisfluorosulfonylimide, and lithium difluorophosphate, the cycle life and high-temperature performance of the battery can be further improved. The reason is that in the mixed lithium salt, lithium difluorophosphate can effectively reduce the impedance of the electrolyte and improve the cycle life of the battery; lithium bisfluorosulfonylimide has better thermal stability and can improve the high-temperature cycle performance of the battery; lithium hexafluorophosphate can passivate aluminum foil and eliminate the negative effects of lithium bisfluorosulfonylimide; and the synergistic effect of the three can further improve the cycle life and high-temperature performance of the battery.

[0052] Further, the mass percentage of lithium hexafluorophosphate is 6%-15%, the mass percentage of lithium bisfluorosulfonylimide is 1%-6%, and the mass percentage of lithium difluorophosphate is 0.5%-1% based on the total mass of the electrolyte.

[0053] It can be understood that the electrolyte of the present application further comprises a solvent, which can be an organic solvent. Illustratively, the solvent can be selected from at least two of chain carbonate, cyclic carbonate, fluorinated cyclic carbonate, fluorinated chain carbonate, chain carboxylate, cyclic carboxylate, and fluorinated chain ether.

[0054] Further, the solvent can be selected from at least two of diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethylene carbonate, propylene carbonate, methyl trifluoroethyl carbonate, difluoroethylene carbonate, ethyl acetate, propyl propionate, γ-butyrolactone, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, and methyl nonafluorobutyl ether.

[0055] In some embodiments, when the solvent is selected from ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, and dimethyl carbonate, the comprehensive performance of the electrolyte can be further improved. Moreover, the total amount of ethylene carbonate and propylene carbonate can be 17.46%-23.22%, and the total amount of ethyl methyl carbonate, diethyl carbonate, and dimethyl carbonate can be 40.74%-54.18%, based on the total mass of the electrolyte.

[0056] The electrolyte of the present application can also include other additives commonly used in the art. For example, the other additives can be selected from at least one of ethylene sulfite, 1,4-butanesultone, 1,3-propanesultone, 1,3-propane sulfonate, ethylene sulfate, maleic anhydride, tris(trimethylsilyl)borate, difluoroethylene carbonate, and vinylene carbonate. In some embodiments, the mass percentage of the other additives can be 0.03%-4%, based on the total mass of the electrolyte. In particular, when the mass percentage of the other additives is 0.5%-3.8%, based on the total mass of the electrolyte, the comprehensive performance of the electrolyte can be further improved.

[0057] The second aspect of the present application provides a battery, wherein the battery comprises the electrolyte described above.

[0058] It can be understood that the battery of the present application also comprises a positive electrode sheet, a negative electrode sheet, a separator, and an outer package.

[0059] The positive electrode sheet of the present application is not particularly limited and can be a positive electrode sheet commonly used in the art. In some embodiments, the positive electrode active material in the positive electrode sheet can be at least one of lithium cobaltate, lithium iron phosphate, and a ternary material. Further, the positive electrode active material can be a ternary material.

[0060] The negative electrode sheet of the present application is not particularly limited and can be a negative electrode sheet commonly used 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 oxygen, and silicon metal compounds. Further, the negative electrode active material can be silicon carbon and / or silicon oxygen.

[0061] In particular, when the high-nickel ternary positive electrode material and the silicon carbon negative electrode material are used together to prepare a battery, the advantages of a 4680 battery can be fully utilized.

[0062] In the specific application process, the electrolyte can generate a stable SEI film on the surface of the negative electrode, and the electrolyte is not easy to produce gas at high temperature, so the battery containing the electrolyte of the application can have excellent normal temperature cycle performance, high temperature cycle performance and high temperature storage performance.

[0063] Hereinafter, the electrolyte of the application and its application will be described in detail through specific examples.

[0064] Example 1

[0065] The battery of the present embodiment is prepared by a method comprising the following steps:

[0066] (1) Preparation of positive electrode sheet

[0067] The positive electrode active material NCM811, the binder polyvinylidene fluoride (PVDF), and the conductive agent acetylene black are mixed in a mass ratio of 96.5:2:1.5, N-methyl pyrrolidone (NMP) is added, and stirring is carried out under the action of a vacuum stirrer until the raw materials are mixed into a uniform flowable positive electrode slurry;

[0068] The positive electrode slurry is uniformly coated on both surfaces of an aluminum foil with a thickness of 7 μm, and after baking in a 5-section oven with different temperature gradients, drying at 120℃ for 8h, and then rolling, the compaction density of the positive electrode active layer is controlled at 3.5g / cm 3 , and the positive electrode sheet is obtained by slitting.

[0069] (2) Preparation of negative electrode sheet

[0070] The negative electrode active material carbon-silicon monoxide@graphite (the mass percentage content of silicon monoxide is 10%), the thickening agent carboxymethyl cellulose sodium (CMC-Na), the binder styrene-butadiene rubber, the conductive agent acetylene black, and the conductive agent single-walled carbon nanotube (SWCNT) are mixed in a mass ratio of 95.9:1:2:1:0.1, deionized water is added, and a negative electrode slurry is obtained under the action of a vacuum stirrer;

[0071] The negative electrode slurry is uniformly coated on both surfaces of a copper foil with a thickness of 6 μm, dried (temperature: 85℃, time: 5h), and rolled to control the compaction density of the negative electrode active layer at 1.65g / cm 3 , and the negative electrode sheet is obtained by die cutting.

[0072] (3) Preparation of electrolyte

[0073] In an argon-filled glove box (moisture <10 ppm, oxygen <1 ppm), ethylene carbonate (EC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), propylene carbonate (PC) were mixed uniformly in a mass ratio of 1.5:1.5:5:2 to obtain a mixed solution, and then a fully dried lithium salt, FEC, silane and an isocyanate compound were rapidly added into the mixed solution to obtain an electrolyte. The specific composition of the electrolyte is shown in Table 1.

[0074] (4) Preparation of the lithium ion battery

[0075] After the positive electrode sheet of step (1), the separator and the negative electrode sheet of step (2) were sequentially stacked, the un-liquid-injected bare battery cell was obtained by winding.

[0076] The bare battery cell was placed in an outer packaging foil, and the electrolyte of step (3) was injected into the dried bare battery cell. After vacuum packaging, standing, formation, shaping, sorting and other processes, the required lithium ion battery was obtained.

[0077] The separator was a coated polyethylene separator with a thickness of 8 μm.

[0078] Example 2-37 and Comparative Example 1

[0079] The electrolyte of Example 2-37 and Comparative Example 1 was basically the same as that of Example 1, and the difference was shown in Table 1.

[0080] The electrolyte of Example 1 was replaced by the electrolyte of Example 2-37 and Comparative Example 1, respectively, to obtain the lithium ion battery of Example 2-37 and Comparative Example 1, respectively.

[0081] Table 1

[0082]

[0083]

[0084] In Table 1, the molecular formula of C is as follows:

[0085]

[0086] Performance test

[0087] The batteries in the examples and comparative examples were subjected to the following performance tests, and the test results are shown in Table 2.

[0088] 1) Initial efficiency test

[0089] Charge the battery at 45°C with 0.1C constant current to 4.2V, record the first step charge capacity as Q1. Next after 45°C aging and secondary sealing, charge the battery at room temperature 25°C with 0.1C constant current to 4.2V, constant voltage 4.2V charge to the cut-off current 0.05C, record the second step charge capacity as Q2. Then discharge the battery with 0.2C to 2.75V, record the first step discharge capacity as Q3. The initial efficiency of the battery = Q3 / (Q1+Q2)*100%.

[0090] 2) Normal temperature cycle performance test

[0091] Charge the battery at room temperature 25°C with 1C constant current to 4.2V, constant voltage 4.2V charge to the cut-off current 0.05C, then discharge the battery with 1C to 2.75V, repeat the charge and discharge for 600 cycles, test and record the discharge capacity of the 600th cycle and divide by the discharge capacity of the 1st cycle, which is the capacity retention rate.

[0092] 3) High temperature cycle performance test

[0093] Charge the battery at high temperature 45°C with 1C constant current to 4.2V, constant voltage 4.2V charge to the cut-off current 0.05C, then discharge the battery with 1C to 2.75V, repeat the charge and discharge for 200 cycles, test and record the discharge capacity of the 200th cycle and divide by the discharge capacity of the 1st cycle, which is the capacity retention rate.

[0094] 4) High temperature storage performance test

[0095] Charge the battery at room temperature 25°C with 1C constant current to 4.2V, constant voltage 4.2V charge to the cut-off current 0.05C, then discharge the battery with 0.5C constant current, the discharge capacity is recorded as C2. Charge the battery at room temperature 25°C with 1C constant current to 4.2V, constant voltage 4.2V charge to the cut-off current 0.05C, then transfer the battery to high temperature 60°C for 7 days, then discharge with 0.5C constant current, the discharge capacity is recorded as C3, the 60°C capacity retention rate = C3 / C2*100%.

[0096] 5) Initial DCIR test

[0097] Charge the battery after trimming at room temperature with 1C to 4.2V, after 5min rest, then discharge with 1C for 30min, after 1h rest, then discharge with 2C for 10s, calculate the DCIR at 50% SOC of the battery.

[0098] Table 2

[0099]

[0100]

[0101]

[0102] As shown in Table 2, by including the specific silane in the electrolyte, the initial efficiency, the normal-temperature cycle performance, the high-temperature storage performance, and the high-temperature cycle performance of the battery can be improved, and the impedance of the battery can be reduced;

[0103] Further, as shown in Example 14 and Example 13, when the isocyanate compound is further included in the electrolyte, the initial efficiency of the battery can be significantly improved while the normal-temperature cycle performance, the high-temperature storage performance, and the impedance of the battery are maintained;

[0104] As shown in Example 14 and Example 15, when the FEC is further included in the electrolyte, the initial efficiency, the normal-temperature cycle performance, and the high-temperature cycle performance of the battery can be significantly improved while the impedance and the high-temperature storage performance of the battery are maintained;

[0105] As shown in Example 1, Example 13-15, when the specific silane, the FEC, and the isocyanate compound are simultaneously included in the electrolyte, the battery can have more excellent initial efficiency, normal-temperature cycle performance, and high-temperature cycle performance while the high-temperature storage performance of the battery is maintained, and the battery can have lower interface impedance;

[0106] As shown in Example 1, Example 4, and Example 2, when the silane has a symmetrical structure, the initial efficiency, the normal-temperature cycle performance, the high-temperature storage performance, and the high-temperature cycle performance of the battery can be further improved, and the interface impedance of the battery can be reduced, and as shown in Example 1 and Example 2, the more the number of unsaturated bonds in the silane, the more the comprehensive performance of the battery is improved;

[0107] As shown in Example 1, Example 4, and Example 3, when the silane contains the Si-O bond, the obtained electrolyte has more excellent comprehensive performance when applied to the battery;

[0108] As shown in Example 1 and Example 5, the electrolyte including the specific content of the silane is more helpful to improve the initial efficiency, the normal-temperature cycle performance, the high-temperature storage performance, and the high-temperature cycle performance of the battery, and is more helpful to reduce the interface impedance of the battery;

[0109] As shown in Example 1, Example 10-12, by further selecting the isocyanate compound, the comprehensive performance of the battery can be improved, and specifically, when the isocyanate compound is selected from the group consisting of methyl diisocyanate, p-phenylene diisocyanate, or 1,4-diisocyanato-2-methylbenzene, the obtained electrolyte can further improve the comprehensive performance of the battery, and in particular, when the isocyanate compound is p-phenylene diisocyanate, the obtained electrolyte can make the battery have more excellent comprehensive performance;

[0110] As can be seen from Example 1 and Example 8, when the lithium salt comprises LiPF6, LiFSI and LiPO2F2, the initial efficiency, the room temperature cycle performance, the high temperature storage performance and the high temperature cycle performance of the battery can be significantly improved, and the interface impedance of the battery is reduced;

[0111] As can be seen from Example 8 and Example 9, by further selecting the content of the lithium salt, the initial efficiency, the room temperature cycle performance, the high temperature storage performance and the high temperature cycle performance of the battery can be improved, and the interface impedance of the battery is reduced.

[0112] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An electrolyte, characterized by, The silane shown in formula 1, fluoroethylene carbonate, isocyanate compound; Formula 1 In formula 1, X is selected from O or N; At least one of R1, R2, R3, R4, R5, R6 is selected from at least one of substituted or unsubstituted C2-C30 alkenyl, substituted or unsubstituted C2-C30 alkynyl; and the rest are each independently selected from at least one of hydrogen, halogen, substituted or unsubstituted C2-C30 alkyl, substituted or unsubstituted C2-C30 alkoxy, substituted or unsubstituted C6-C60 aryl; The mass percentage of the silane is 0.5%-2%, the mass percentage of the fluoroethylene carbonate is 1%-20%, and the mass percentage of the isocyanate compound is 0.1%-0.5%, based on the total mass of the electrolyte.

2. The electrolyte according to claim 1, characterized in that, The silane comprises Si-O bond; and / or, The silane has symmetrical structure.

3. The electrolyte of claim 1, wherein The silane is selected from the compound shown in the following structure; 。 4. The electrolyte according to any one of claims 1 to 3, characterized in that, The electrolyte further comprises lithium salt, and the mass percentage of the lithium salt is 12.5%-18%, based on the total mass of the electrolyte.

5. A battery, characterized by The electrolyte comprises the electrolyte according to any one of claims 1-4.

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