Electrolyte and use thereof

Abstract

The present application provides an electrolyte and its application, the electrolyte comprises an organic silane compound containing an oxime group. The electrolyte of the present application has a simple composition, and when the electrolyte is 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, protects the electrode, and further helps to improve the performance of the secondary battery.

Description

Technical Field

[0001] This invention relates to an electrolyte and its application, belonging to the field of energy technology. Background Technology

[0002] With technological advancements and diversified energy demands, traditional energy sources are being consumed at an accelerated pace, prompting countries to expedite their strategic deployments for new energy technologies. Among these, power batteries are rapidly emerging alongside the development of new energy vehicles, while energy storage batteries are also gaining momentum with the development of clean energy. Since 2017, competition in the new energy vehicle industry has intensified, with power battery companies continuously developing and updating their products to find chemical power systems that better suit the market, meeting users' demands for high specific energy and extended range, with the aim of comprehensively replacing traditional energy-powered passenger cars and buses.

[0003] Lithium-ion batteries are one of the important products in new energy technologies. Traditional lithium-ion batteries use graphite to prepare the negative electrode, and the specific capacity of graphite is 372 mAh g. -1 The current technology is no longer sufficient 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 battery cycling, which will lead to the continuous damage of the interface film between the anode sheet and the electrolyte, causing the electrolyte to decompose continuously and ultimately deteriorating the battery performance. Summary of the Invention

[0004] This invention provides an electrolyte that, when used in a battery, helps to form a high-quality SEI film on the negative electrode surface and effectively suppresses side reactions in silicon-based batteries, thereby reducing battery impedance and improving the battery's high-temperature cycling and high-temperature storage performance.

[0005] The present invention also provides a battery containing the above-mentioned electrolyte, thus the battery has superior electrochemical performance.

[0006] The present invention provides an electrolyte comprising an organosilanes containing an oxime group.

[0007] The electrolyte as described above, wherein the organosilane compound has the structural formula shown in any one of Formula 1-2;

[0008]

[0009] In Formulas 1 and 2, R1, R2, R3, R5, and R6 are each independently selected from at least one of hydrogen, halogen, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C2-C30 alkenyl, substituted or unsubstituted C2-C30 alkynyl, substituted or unsubstituted C1-C30 alkoxy, and substituted or unsubstituted C1-C60 aryl.

[0010] R4 and R7 are each independently selected from at least one of the following: substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C2-C30 alkenyl, substituted or unsubstituted C2-C30 alkynyl, substituted or unsubstituted C1-C30 alkoxy, and substituted or unsubstituted C1-C60 aryl.

[0011] In the electrolyte as described above, R1, R2, R3, R5, and R6 are each independently selected from at least one of methyl, ethyl, or vinyl; and / or,

[0012] R4 and R7 are each independently selected from at least one of butyl and propyl.

[0013] The electrolyte as described above, wherein the organosilane compound is selected from compounds with the structures shown below;

[0014]

[0015]

[0016] The electrolyte as described above, wherein the mass percentage of the organosilane compound is 0.5%-2% based on the total mass of the electrolyte.

[0017] The electrolyte as described above further includes fluoroethylene carbonate and / or isocyanate compounds.

[0018] The electrolyte as described above, wherein the mass percentage of the fluoroethylene carbonate is 1%-20% based on the total mass of the electrolyte.

[0019] In the electrolyte as described above, 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 further includes a lithium salt, wherein the lithium salt has a mass percentage content of 12.5%-18% based on the total mass of the electrolyte.

[0021] The present invention provides a battery comprising the electrolyte as described above.

[0022] The electrolyte of the present invention has a simple composition. When used in batteries, such as secondary batteries, it helps to form a denser and more stable SEI film on the negative electrode surface of the secondary battery, which protects the electrode and thus improves the performance of the secondary battery.

[0023] The battery of the present invention includes the aforementioned electrolyte, and therefore 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 invention has superior electrochemical performance, such as high-temperature cycling and high-temperature storage performance. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0025] A first aspect of the present invention provides an electrolyte comprising an organosilane compound containing an oxime group.

[0026] The electrolyte of this invention comprises an organosilane compound containing an oxime group (-ON=C). In lithium-ion batteries, under high-temperature conditions, transition metal ions in the positive electrode material dissolve significantly and subsequently migrate to the negative electrode, catalyzing electrolyte decomposition. The oxime group possesses excellent coordination properties, effectively complexing the transition metal ions in the electrolyte and reducing their negative impact. Furthermore, the silane component of the organosilane compound can eliminate water and hydrofluoric acid in the electrolyte, reducing the possibility of side reactions. Notably, the oxime group can also generate highly elastic polymers, thus effectively protecting the electrode interface. In summary, the organosilane compound containing an oxime group of this invention can effectively interrupt the pathways for side reactions in the electrolyte, thereby improving the electrochemical performance of the battery.

[0027] In some embodiments of the present invention, the organosilane compound has the structural formula shown in any one of Formulas 1-2;

[0028]

[0029] In Formulas 1 and 2, R1, R2, R3, R5, and R6 are each independently selected from at least one of hydrogen, halogen, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C2-C30 alkenyl, substituted or unsubstituted C2-C30 alkynyl, substituted or unsubstituted C1-C30 alkoxy, and substituted or unsubstituted C1-C60 aryl.

[0030] R4 and R7 are each independently selected from at least one of the following: substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C2-C30 alkenyl, substituted or unsubstituted C2-C30 alkynyl, substituted or unsubstituted C1-C30 alkoxy, and substituted or unsubstituted C1-C60 aryl.

[0031] Specifically, the halogen of the present invention can be F, Cl, Br, or I;

[0032] The substituted or unsubstituted C1-C30 alkyl group can be cycloalkyl, branched alkyl, straight alkyl, substituted cycloalkyl, substituted branched alkyl, or substituted straight alkyl;

[0033] The substituted or unsubstituted C2-C30 alkenyl group can be a straight-chain alkenyl, a branched alkenyl, a cyclic alkenyl (cyclopentadienyl), a substituted straight-chain alkenyl, or a substituted branched alkenyl.

[0034] The substituted or unsubstituted C2-C30 alkynyl group can be a straight-chain alkynyl, a branched-chain alkynyl, a substituted branched-chain alkynyl, a substituted straight-chain alkynyl, or a cyclic alkynyl.

[0035] The substituted or unsubstituted C1-C30 alkoxy group can be a straight-chain alkoxy, a branched-chain alkoxy, a substituted branched-chain alkoxy, or a substituted straight-chain alkoxy.

[0036] The aryl group of C1-C60, whether substituted or unsubstituted, can be phenyl, biphenyl, substituted phenyl, or substituted biphenyl.

[0037] The present invention does not impose any particular limitation on the substituents in R1, R2, R3, R4, R5, R6, R7, and R8, and they can be substituents commonly used in the art, such as at least one of halogen, ester, nitro, amino, cyano, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted alkoxy, cyano, isocyanate, isocyanate group, and substituted or unsubstituted aryl.

[0038] The organosilane compounds shown in any of Formulas 1-2 are less likely to produce acidic substances during long-term storage of the electrolyte, which helps to extend the battery's lifespan and improve its electrochemical performance. Furthermore, the organosilane compounds shown in any of Formulas 1-2 can also eliminate HF acid in the electrolyte, preventing HF acid from corroding the electrode materials and improving the battery's electrochemical performance.

[0039] It is worth mentioning that when organosilane compounds contain Si-O bonds, the Si-O bonds have higher bond energies, which not only help to further improve the high-temperature resistance of the electrolyte, but also can form a more high-temperature resistant SEI film during the charging and discharging process of the battery, further improving the high-temperature performance of the battery.

[0040] When organosilane compounds have symmetrical structures (axially symmetric or centrosymmetric structures), not only can the preparation cost of organosilane compounds be reduced and their large-scale application promoted, but also the molecules of symmetrical organosilane compounds have lower activity, making them easier to store and less prone to side reactions during storage, which helps to improve the electrochemical performance of batteries.

[0041] In some embodiments of the present invention, R1, R2, R3, R5, and R6 are each independently selected from at least one of methyl, ethyl, or vinyl; and / or,

[0042] R4 and R7 are each independently selected from at least one of butyl and propyl.

[0043] Specifically, the butyl group can be cis-butyl or isobutyl, and the propyl group can be substituted propyl or unsubstituted propyl.

[0044] For example, the organosilane compound is selected from compounds with the structures shown below;

[0045]

[0046] It is understood that the organosilane compounds described above in this invention can be obtained commercially or synthesized in the laboratory using methods commonly used in the art. Furthermore, the compounds shown in the above structural formulas are merely illustrative and can be either cis or trans structures. For example, A4 is a trans compound, and A5 is a cis compound.

[0047] Since organosilane compounds form a stable SEI film on the surface of the negative electrode during battery charging and discharging, improving the battery's electrochemical performance, it is understood that the content of organosilane compounds in the electrolyte has a crucial impact on battery performance. Therefore, this invention aims to improve the overall battery performance by further selecting the content of organosilane compounds in the electrolyte. Exemplarily, in some embodiments of this invention, the mass percentage of organosilane compounds is 0.5%-2% based on the total mass of the electrolyte.

[0048] In some embodiments of the present invention, the electrolyte further includes fluoroethylene carbonate and / or isocyanate compounds.

[0049] It is understood that the electrolyte may include organosilane compounds and fluoroethylene carbonate; the electrolyte may also include organosilane compounds and isocyanate compounds; the electrolyte may also include organosilane compounds, isocyanate compounds and fluoroethylene carbonate.

[0050] In this invention, when the electrolyte includes organosilane compounds and fluoroethylene carbonate (FEC), the FEC forms a stable interfacial film on the electrode surface, effectively improving the battery's cycle performance. The oxime groups in the organosilane compounds can generate highly elastic polymers that complement the interfacial film formed by the FEC, creating a more stable and dense SEI film that protects the negative electrode and improves the battery's electrochemical performance. The silane components of the organosilane compounds can eliminate water and hydrofluoric acid in the electrolyte, cutting off the side reaction pathways of FEC and suppressing the negative effects of FEC decomposition and gas production at high temperatures. Simultaneously, the oxime groups (-ON=C) in the organosilane compounds have excellent coordination properties, effectively complexing transition metal ions in the electrolyte and reducing the negative impacts of these ions. Therefore, the synergy between organosilane compounds and FEC can overcome the high-temperature gas production defect of FEC and improve the battery's high-temperature performance.

[0051] When the electrolyte includes isocyanate compounds and organosilane compounds, the isocyanate compounds can eliminate the side reactions generated by silanes in the system, avoid the generation of trimethylsilyl fluoride (TMSF), and improve the ability of silanes to suppress high-temperature gas generation. During the charging and discharging process of the battery, the isocyanate compounds will generate polyurethane. Polyurethane not only has excellent elasticity, but also performs well in terms of heat preservation. It can effectively suppress the expansion of silicon materials in the negative electrode and the interference of external high temperature on the generated interface film, thereby improving the high-temperature storage performance and high-temperature cycle performance of the battery.

[0052] When the electrolyte simultaneously includes FEC, organosilane compounds, and isocyanate compounds, the synergistic effect of these compounds can generate a more stable interfacial film, protecting the electrodes and improving the battery's electrochemical performance. Furthermore, organosilane compounds can suppress high-temperature gas generation caused by FEC, and isocyanate compounds can enhance the ability of organosilane compounds to suppress high-temperature gas generation. The synergistic effect of these three compounds can improve the battery's electrochemical performance.

[0053] This invention does not specifically limit the isocyanate compounds and can use isocyanate compounds commonly used in the art. For example, the isocyanate compound can be selected from at least one of hexamethyl diisocyanate (B1), terephthalic diisocyanate (B2), triisocyanate-methyl-silane, 1,4-diisocyanate-2-toluene (B3), γ-isocyanate-propyltrimethoxysilane (B4), γ-isocyanate-propyltriethoxysilane, γ-isocyanate-propylmethyldimethoxysilane, isocyanate-propylmethyldiethoxysilane, γ-isocyanate-propylmethyldimethoxysilane, α-isocyanate-methyltrimethoxysilane, α-isocyanate-methyltriethoxysilane, and α-isocyanate-methyldimethoxysilane.

[0054] Furthermore, when the isocyanate compound is selected from at least one of hexamethyl diisocyanate (B1), terephthalic diisocyanate (B2), and 1,4-diisocyanate-2-toluene (B3), the isocyanate compound, in combination with FEC and organosilane compound, can further improve the electrochemical performance of the battery.

[0055] It is understood that the content of FEC and isocyanate compounds in the electrolyte has a crucial impact on battery performance. Therefore, this invention aims to improve the overall battery performance by further selecting the content of FEC and isocyanate compounds in the electrolyte. Exemplarily, in some embodiments of this invention, the mass percentage of fluoroethylene carbonate is 1%-20% based on the total mass of the electrolyte; and / or,

[0056] Based on the total mass of the electrolyte, the mass percentage of isocyanate compounds is 0.1%-0.5%.

[0057] In some embodiments of the present invention, the electrolyte further includes a lithium salt, wherein the mass percentage of the lithium salt is 12.5%-18% based on the total mass of the electrolyte.

[0058] In this invention, when the content of lithium salt is within the above-mentioned range, lithium ions in the lithium salt can preferentially participate in the construction of the interface film, and anions in the lithium salt can also participate in the construction of the interface film. Excess lithium salt will enrich the interface film with lithium-containing compounds during the construction of the interface film, reduce the interfacial impedance of the interface film, and improve the low-temperature performance of the battery. Furthermore, excess lithium salt also has a self-sacrificing effect, reducing the loss of active lithium in the positive electrode active material of the battery, thereby improving the first efficiency of the battery.

[0059] Furthermore, based on the total mass of the electrolyte, the total mass percentage of lithium salt can be 15%-18%.

[0060] This invention does not specifically limit the lithium salt and can use any lithium salt commonly used in the art. Exemplarily, the lithium salt can be selected from at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium tetrafluoroborate, lithium bis(oxalate-borate), lithium difluorooxalate phosphate, and lithium tetrafluorooxalate phosphate. In some embodiments, when the lithium salt is a mixed lithium salt including lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, and lithium difluorophosphate, the cycle life and high-temperature performance of the battery can be further improved. This is because: in the mixed lithium salt, lithium difluorophosphate can effectively reduce the electrolyte impedance and improve the battery's cycle life; lithium bis(fluorosulfonyl)imide has better thermal stability and can improve the battery's high-temperature cycle performance; lithium hexafluorophosphate can passivate the aluminum foil and eliminate the negative effects of lithium bis(fluorosulfonyl)imide. The synergistic effect of these three components can further improve the battery's cycle life and high-temperature performance.

[0061] Furthermore, based on the total mass of the electrolyte, the mass percentage of lithium hexafluorophosphate is 6%-15%, the mass percentage of lithium bis(fluorosulfonyl)imide (LiFSI) is 1%-6%, and the mass percentage of lithium difluorophosphate (LiPO2F2) is 0.5%-1%.

[0062] It is understood that the electrolyte of the present invention also includes a solvent, which can be an organic solvent. For example, the solvent can be selected from at least two of the following: chain carbonates, cyclic carbonates, fluorocyclic carbonates, fluorochain carbonates, chain carboxylic esters, cyclic carboxylic esters, and fluorochain ethers.

[0063] Furthermore, the solvent may be selected from at least two of diethyl carbonate, dimethyl carbonate, methyl ethyl 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.

[0064] In some embodiments, when the solvent is selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, and dimethyl carbonate, the overall performance of the electrolyte can be further improved. Furthermore, based on the total mass of the electrolyte, the total amount of ethylene carbonate and propylene carbonate added can be 17.46%-23.22%, and the total amount of methyl ethyl carbonate, diethyl carbonate, and dimethyl carbonate added can be 40.74%-54.18%.

[0065] The electrolyte of the present invention may also include other additives commonly used in the art. For example, it may be selected from at least one of vinyl sulfite, 1,4-butanesulfonate lactone, 1,3-propenesulfonate lactone, 1,3-propanesulfonate lactone, vinyl sulfate, maleic anhydride, tris(trimethylsilane)borate, difluoroethylene carbonate, and vinylene carbonate. In some embodiments, the mass percentage of other additives may be 0.03%-4% based on the total mass of the electrolyte. In particular, when the mass percentage of other additives is 0.5% to 3.8% based on the total mass of the electrolyte, the overall performance of the electrolyte can be further improved.

[0066] A second aspect of the present invention provides a battery comprising the electrolyte described above.

[0067] It is understood that the battery of the present invention also includes a positive electrode, a negative electrode, a separator, and an outer packaging.

[0068] This invention does not impose any particular limitation on the positive electrode sheet, and any positive electrode sheet commonly used in the art can be used. 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 ternary materials. Further, the positive electrode active material can be a ternary material.

[0069] This invention does not impose any particular limitation on the negative electrode sheet, and any negative electrode sheet commonly used in the art can be used. In some embodiments, the negative electrode active material in the negative electrode sheet may 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 may be silicon-carbon and / or silicon-oxygen.

[0070] In particular, when high-nickel ternary cathode materials and silicon-carbon anode materials are used together to prepare batteries, the advantages of 4680 batteries can be fully utilized.

[0071] In practical applications, the electrolyte will generate a stable SEI film on the surface of the negative electrode, and the electrolyte is not prone to gas generation at high temperatures. Therefore, batteries containing the electrolyte of this invention can have excellent room temperature cycling performance, high temperature cycling performance and high temperature storage performance.

[0072] The electrolyte of the present invention and its application are described in detail below through specific embodiments.

[0073] Example 1

[0074] The battery in this embodiment is prepared by a method including the following steps:

[0075] (1) Preparation of positive electrode

[0076] 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. N-methylpyrrolidone (NMP) was added, and the mixture was stirred under vacuum until all the raw materials were mixed into a uniform and fluid positive electrode slurry.

[0077] The positive electrode slurry was uniformly coated onto two surfaces of a 7μm thick aluminum foil. After baking in ovens with five different temperature gradients, it was dried in an oven at 120℃ for 8 hours. Then, it was rolled to control the compaction density of the positive electrode active layer to 3.5 g / cm³. 3 The positive electrode is obtained by cutting.

[0078] (2) Preparation of negative electrode sheet

[0079] The negative electrode active material silicon suboxide@graphite (silicon suboxide mass percentage is 10%), thickener sodium carboxymethyl cellulose (CMC-Na), binder styrene-butadiene rubber, conductive agent acetylene black, and conductive agent single-walled carbon nanotubes (SWCNT) were mixed in a mass ratio of 95.9:1:2:1:0.1, deionized water was added, and the negative electrode slurry was obtained under the action of a vacuum stirrer.

[0080] The negative electrode slurry was uniformly coated on both surfaces of a 6μm thick copper foil, and then dried (temperature: 85℃, time: 5h) and rolled to control the compaction density of the negative electrode active layer to 1.65g / cm³. 3 The negative electrode sheet is obtained by die cutting.

[0081] (3) Electrolyte preparation

[0082] In an argon-filled glove box (moisture <10ppm, oxygen <1ppm), ethylene carbonate (EC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), and propylene carbonate (PC) were mixed uniformly at a mass ratio of 1.5:1.5:5:2 to obtain a mixed solution. Sufficiently dried lithium salt, FEC, organosilane compound, and isocyanate compound were quickly added to the mixed solution, as detailed in Table 1.

[0083] (4) Preparation of lithium-ion batteries

[0084] After the positive electrode sheet, separator and negative electrode sheet of step (2) are stacked in sequence, they are wound to obtain a bare cell without liquid filling.

[0085] The bare cell is placed in the outer packaging foil, and the electrolyte from step (3) is injected into the dried bare cell. After vacuum sealing, standing, formation, shaping and sorting, the required lithium-ion battery is obtained.

[0086] The diaphragm is an 8μm thick coated polyethylene diaphragm.

[0087] Examples 2-28, Comparative Example 1

[0088] The electrolytes in Examples 2-28 and Comparative Example 1 have the same composition as those in Example 1, with the differences shown in Table 1.

[0089] The electrolyte in Example 1 was replaced with the electrolyte in Examples 2-28 and Comparative Example 1, respectively, to obtain lithium-ion batteries of Examples 2-28 and Comparative Example 1, respectively.

[0090] Table 1

[0091]

[0092]

[0093] In Table 1, compound C is shown below:

[0094]

[0095] Performance testing

[0096] The following performance tests were performed on the batteries in the examples and comparative examples, and the test results are shown in Table 2.

[0097] 1) First-time effect test

[0098] The battery was charged at 45°C with a constant current of 0.1C to 4.2V, and the first charging capacity was recorded as Q1. After aging at 45°C and secondary sealing, the battery was charged at room temperature (25°C) with a constant current of 0.1C to 4.2V, and then charged at a constant voltage of 4.2V until the cutoff current reached 0.05C. The second charging capacity was recorded as Q2. The battery was then discharged at 0.2C to 2.75V, and the first discharge capacity was recorded as Q3. The initial battery efficiency = Q3 / (Q1+Q2)*100%.

[0099] 2) Room temperature cycling performance test

[0100] The battery was charged at 1C constant current to 4.2V at room temperature (25℃), then charged at 4.4V constant voltage to the cutoff current of 0.05C. The battery was then discharged at 1C to 2.75V. This charge-discharge cycle was repeated for 600 cycles. The discharge capacity of the 600th cycle was recorded and divided by the discharge capacity of the 1st cycle to obtain the capacity retention rate.

[0101] 3) High-temperature cycling performance test

[0102] The battery was charged at a high temperature of 45°C with 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. This charge-discharge cycle was repeated 200 times. The capacity retention rate was obtained by recording the discharge capacity after the 200th cycle and dividing it by the discharge capacity after the first cycle.

[0103] 4) High-temperature storage performance test

[0104] The battery was charged at room temperature (25℃) with a constant current of 1C to 4.2V, and then charged at a constant voltage of 4.2V until the cutoff current was 0.05C. The battery was then discharged at a constant current of 0.5C, and the discharge capacity was recorded as C2. At room temperature (25℃), the battery was charged at a constant current of 1C to 4.2V, and then charged at a constant voltage of 4.42C until the cutoff current was 0.05C. The battery was then transferred to a high temperature of 60℃ and left to stand for 7 days. It was then discharged at a constant current of 0.5C, and the discharge capacity was recorded as C3. The capacity retention rate at 60℃ was calculated as C3 / C2 * 100%.

[0105] 5) Initial DCIR test

[0106] After capacity grading, the battery was charged to 4.2V at 1C at room temperature, left to stand for 5 minutes, then discharged at 1C for 30 minutes, left to stand for 1 hour, and then discharged at 2C for 10 seconds. The DCIR of the battery at 50% SOC was calculated.

[0107] Table 2

[0108]

[0109]

[0110] As shown in Table 2, adding a specific amount of silane to the electrolyte can improve the battery's initial efficiency, room temperature cycle performance, high temperature cycle performance, and high temperature storage performance, and can also reduce the battery's impedance.

[0111] Furthermore, as can be seen from Examples 14 and 15-16, by further selecting the content of lithium salt in the electrolyte, the battery's initial efficiency, room temperature cycle performance, high temperature cycle performance, and high temperature storage performance can be improved, and the battery's impedance can be reduced.

[0112] As can be seen from Examples 16 and 12, by further selecting the composition of lithium salt in the electrolyte, the battery's initial efficiency, room temperature cycle performance, high temperature cycle performance, and high temperature storage performance can be further improved, while reducing the battery's impedance.

[0113] As can be seen from Examples 12 and 11, when the electrolyte also includes isocyanate compounds, the high-temperature cycle performance and high-temperature storage performance of the battery can be improved without affecting the first-efficiency performance, room temperature cycle performance and impedance.

[0114] As can be seen from Examples 13 and 12, when the electrolyte also includes FEC, the battery's high-temperature cycle performance, high-temperature storage performance, and impedance change can be significantly improved while the battery's first efficiency and room-temperature cycle performance are relatively small.

[0115] As can be seen from Examples 3, 11, and 13, when the electrolyte contains specific silanes, FECs, and isocyanate compounds, the battery can have excellent first-efficiency performance, room temperature cycling performance, high temperature cycling performance, and high temperature storage performance, and the battery impedance can be reduced.

[0116] As can be seen from Examples 1, 3 and 2, when silane has a symmetrical structure, the resulting electrolyte can improve the overall performance of the battery when applied to it.

[0117] As can be seen from Examples 3 and 9, the overall performance of the battery can be improved by further selecting the content of silane in the electrolyte.

[0118] As can be seen from Examples 3 and 10, by further selecting the content of isocyanates in the electrolyte, the overall performance of the battery can be improved.

[0119] As can be seen from Examples 3 and 8, the overall performance of the battery can be improved by further selecting the content of FEC in the electrolyte.

[0120] As can be seen from Examples 3, 4, 6 and 5, the overall performance of the battery can be improved by making specific selections of isocyanate compounds.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrolyte, characterized in that, This includes organosilanes containing oxime groups, fluoroethylene carbonates, and isocyanates; The organosilane compound has the structural formula shown in any one of Formula 1-2, and the organosilane compound has an axially symmetric structure or a centrosymmetric structure. Formula 1; Formula 2; In Formulas 1 and 2, R1, R2, R3, R5, and R6 are each independently selected from at least one of methyl, ethyl, or vinyl groups; R4 and R7 are each independently selected from at least one of butyl and propyl; Based on the total mass of the electrolyte, the mass percentage of the organosilane compound 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%.

2. The electrolyte according to claim 1, characterized in that, The organosilane compound is selected from compounds with the following structures; 。 3. The electrolyte according to any one of claims 1-2, characterized in that, The electrolyte also includes lithium salt, and the mass percentage of the lithium salt is 12.5%-18% based on the total mass of the electrolyte.

4. A battery, characterized in that, Includes the electrolyte according to any one of claims 1-3.

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