Non-aqueous electrolyte and battery

Abstract

A non-aqueous electrolyte, comprising a non-aqueous organic solvent, an electrolyte salt, and additive. The additive comprises a compound represented by structural formula 1: structural formula 1. The non-aqueous electrolyte satisfies the following conditions: 0.05≤a*w / F≤3, 10≤F≤50, 2≤a≤10, and 0.5≤w≤5, wherein F is the surface tension of the non-aqueous electrolyte, in units of N / m; a is the viscosity of the non-aqueous electrolyte at 25°C, in units of mPa.s; and w is the mass percentage content of the compound represented by structural formula 1 in the non-aqueous electrolyte, in units of wt%. In addition, further disclosed is a battery comprising the non-aqueous electrolyte. The non-aqueous electrolyte can effectively penetrate a negative electrode active material layer, improving the lithium-ion deposition uniformity, thereby facilitating improvement of the cycle performance and high-temperature performance of batteries.

Description

Non-aqueous electrolyte and battery Technical Field

[0001] The present invention belongs to the technical field of energy storage devices, and in particular relates to a non-aqueous electrolyte and a battery. Background Art

[0002] Lithium-ion batteries, due to their advantages such as high operating voltage, wide operating temperature range, high energy and power density, no memory effect, and long cycle life, have been widely used in 3C digital products such as mobile phones and laptops, as well as in new energy vehicles. In recent years, with the continuous development of lightweight and thin 3C digital products and the increasing demand for mileage in the power battery market, the battery industry is increasingly demanding higher energy density of lithium-ion batteries.

[0003] Under this market trend, batteries tend to use high-density, low-porosity positive and negative electrodes and thin-layer separators to increase the proportion of positive and negative electrode active materials in the battery and improve the battery's energy density. However, in this battery system, the porosity is very low, resulting in insufficient diffusion and infiltration of the electrolyte on the electrode, causing the aging time to be continuously extended during the battery manufacturing process, reducing battery manufacturing efficiency. At the same time, due to the limited diffusion of the electrolyte in the active material, as the cycle test progresses, the additive components in the pores are consumed, and the additives in the residual electrolyte cannot be replenished in time, which in turn causes the battery to fail during cycling. If the residual electrolyte volume of the battery is forcibly increased, the free electrolyte in the battery increases. Under high temperature conditions, the electrolyte reacts with the positive and negative electrodes, increasing gas production and causing degradation of high-temperature storage performance.

[0004] There are currently two ways to solve this problem from the electrolyte aspect: one is to add low-viscosity solvents, such as ethyl acetate, which can reduce the viscosity of the electrolyte, promote electrolyte infiltration, and improve the battery's cycle, rate and other performance; the other is to forcibly increase the amount of residual electrolyte in the battery, which increases the amount of free electrolyte in the battery, improves the infiltration efficiency from the diffusion dynamics of the electrolyte, and causes degradation of high-temperature storage performance. However, both methods will reduce the high-temperature stability of the battery, resulting in poor high-temperature performance of the electrolyte and easy flatulence. Therefore, for high-density, low-porosity battery systems, how to improve cycle performance without degrading the high-temperature performance of the battery is an issue that the industry urgently needs to solve.

[0005] Summary of the Invention

[0006] In view of the problems of insufficient cycle performance and high-temperature performance in existing high-density battery systems, the present invention provides a non-aqueous electrolyte and a battery.

[0007] The technical solutions adopted by the present invention to solve the above technical problems are as follows:

[0008] In one aspect, the present invention provides a non-aqueous electrolyte solution comprising a non-aqueous organic solvent, an electrolyte salt, and an additive, wherein the additive comprises a compound represented by structural formula 1:

[0009] wherein n is selected from an integer of 2 to 5, and R1 is selected from a C1 to C8 alkyl group, a C2 to C8 alkenyl group, a C2 to C8 alkynyl group, or a C5 to C10 aryl group;

[0010] The non-aqueous electrolyte satisfies the following conditions:

[0011] 0.05≤a*w / F≤3, and 10≤F≤50, 2≤a≤10, 0.5≤w≤5;

[0012] Wherein, F is the surface tension of the non-aqueous electrolyte, in N / m;

[0013] a is the viscosity of the non-aqueous electrolyte at 25°C, in mPa.s;

[0014] w is the mass percentage of the compound represented by structural formula 1 in the non-aqueous electrolyte, in wt%.

[0015] Optionally, the non-aqueous electrolyte meets the following conditions:

[0016] 0.1≤a*w / F≤0.6.

[0017] Optionally, the surface tension F of the non-aqueous electrolyte is 15 to 40 N / m.

[0018] Optionally, the viscosity a of the non-aqueous electrolyte at 25° C. is 2.5 to 7 mPa.s.

[0019] Optionally, the mass percentage content w of the compound represented by structural formula 1 in the non-aqueous electrolyte is 0.8% to 3%.

[0020] Optionally, the compound shown in Structural Formula 1 is a symmetrical structure.

[0021] Optionally, the compound represented by structural formula 1 includes one or more of the following compounds:

[0022] Optionally, the additive further includes at least one of a cyclic sulfate compound, a sultone compound, a cyclic carbonate compound, a phosphate compound, a borate compound and a nitrile compound.

[0023] Optionally, the cyclic sulfate ester compound includes at least one of vinyl sulfate, propylene sulfate, and methyl vinyl sulfate.

[0024] Optionally, the sultone compound includes at least one of 1,3-propane sultone, 1,4-butane sultone, and 1,3-propene sultone.

[0025] Optionally, the cyclic carbonate compound includes at least one of vinylene carbonate, ethylene carbonate, methylene carbonate, fluoroethylene carbonate, trifluoromethylethylene carbonate, bisfluoroethylene carbonate or the compound shown in Structural Formula 2:

[0026] In the structural formula 2, R 21 、R 22 、R 23 、R 24 、R 25 、R 26 Each is independently selected from a hydrogen atom, a halogen atom, and a C1-C5 group.

[0027] Optionally, the phosphate compound includes at least one of tris(trimethylsilyl)phosphate, tris(triethylsilyl)phosphate, or the compound shown in Structural Formula 3:

[0028] In the structural formula 3, R 31 、R 32 、R 33 Each independently selected from C1-C5 saturated hydrocarbon group, C1-C5 unsaturated hydrocarbon group, C1-C5 halogenated hydrocarbon group, -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and R 31 、R 32 、R 33 At least one of them is an unsaturated hydrocarbon group.

[0029] Optionally, the borate compound includes at least one of tris(trimethylsilyl)borate and tris(triethylsilyl)borate.

[0030] Optionally, the nitrile compound includes at least one of succinonitrile, glutaronitrile, ethylene glycol bis(propionitrile) ether, hexanetrionitrile, adiponitrile, pimelonitrile, suberonitrile, azelaic acid dinitrile, and sebacononitrile.

[0031] In another aspect, the present invention provides a battery comprising a positive electrode, a negative electrode, and the non-aqueous electrolyte as described above.

[0032] Optionally, the negative electrode includes a negative electrode active material layer, and the compaction density of the negative electrode active material layer is 1.5 to 1.8 g / cm 3 .

[0033] The non-aqueous electrolyte provided by the present invention is suitable for a high-density negative electrode system. The compound shown in Structural Formula 1 is added to the non-aqueous electrolyte as an additive. The inventors have found through extensive research that when the surface tension F of the non-aqueous electrolyte, the viscosity a of the non-aqueous electrolyte and the mass percentage content w of the compound shown in Structural Formula 1 meet the conditions of 0.05≤a*w / F≤3, and 10≤F≤50, 2≤a≤10, 0.5≤w≤5, the obtained non-aqueous electrolyte can effectively improve the cycle performance of high-density negative electrode batteries. In particular, the high-temperature storage performance of high-density negative electrode batteries does not deteriorate due to the improvement of the cycle performance, but is improved instead. It is speculated that this is because the compound shown in Structural Formula 1 is a Branched cycloalkanes have weak polarity themselves, and when combined with polar non-aqueous organic solvents, they can adjust the interfacial polarity of the non-aqueous electrolyte. The interfacial polarity of the non-aqueous electrolyte, together with the viscosity and surface tension of the electrolyte, affects the permeability of the non-aqueous electrolyte to the negative electrode active material layer. Therefore, by adjusting the content of the compound shown in structural formula 1 and the viscosity and surface tension of the non-aqueous electrolyte, the non-aqueous electrolyte can better penetrate the highly compacted negative electrode active material layer, which is beneficial to ensure the uniformity of lithium ion intercalation and deintercalation in the negative electrode active material layer, avoid problems such as capacity reduction and lithium dendrites caused by uneven deposition, and thus ensure the stability of the non-aqueous electrolyte in circulation at high temperatures and improve the high temperature performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is an example diagram of different interface integrity of the negative electrode provided by the present invention. DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] An embodiment of the present invention provides a non-aqueous electrolyte solution comprising a non-aqueous organic solvent, an electrolyte salt, and an additive, wherein the additive comprises a compound represented by structural formula 1:

[0037] wherein n is selected from an integer of 2 to 5, and R1 is selected from a C1 to C8 alkyl group, a C2 to C8 alkenyl group, a C2 to C8 alkynyl group, or a C5 to C10 aryl group;

[0038] The non-aqueous electrolyte satisfies the following conditions:

[0039] 0.05≤a*w / F≤3, and 10≤F≤50, 2≤a≤10, 0.5≤w≤5;

[0040] Wherein, F is the surface tension of the non-aqueous electrolyte, in N / m;

[0041] a is the viscosity of the non-aqueous electrolyte at 25°C, in mPa.s;

[0042] w is the mass percentage of the compound represented by structural formula 1 in the non-aqueous electrolyte, in wt%.

[0043] The inventors have found through extensive research that when the surface tension F of the non-aqueous electrolyte, the viscosity a of the non-aqueous electrolyte, and the mass percentage content w of the compound shown in structural formula 1 meet the conditions 0.05≤a*w / F≤3, and 10≤F≤50, 2≤a≤10, 0.5≤w≤5, the obtained non-aqueous electrolyte can effectively improve the cycle performance of high-pressure negative electrode batteries. In particular, the high-temperature storage performance of high-pressure negative electrode batteries does not deteriorate due to the improvement of cycle performance, but is improved. It is speculated that this is because the compound shown in structural formula 1 is a cycloalkane with a branched chain, which has a weak polarity itself and is combined with a polar non-aqueous organic solvent. , the interfacial polarity of the non-aqueous electrolyte can be adjusted, and the interfacial polarity of the non-aqueous electrolyte, the viscosity of the electrolyte and the surface tension jointly affect the permeability of the non-aqueous electrolyte to the negative electrode active material layer. Therefore, by adjusting the content of the compound shown in structural formula 1 and the viscosity and surface tension of the non-aqueous electrolyte, the non-aqueous electrolyte can better penetrate the high-density negative electrode active material layer, which is beneficial to ensure the uniformity of lithium ion intercalation and deintercalation in the negative electrode active material layer, avoid problems such as capacity reduction and lithium dendrites caused by uneven deposition, and thus ensure the stability of the non-aqueous electrolyte in circulation at high temperature and improve the high temperature performance of the battery.

[0044] In a preferred embodiment, the non-aqueous electrolyte satisfies the following conditions:

[0045] 0.1≤a*w / F≤0.6.

[0046] When the surface tension F of the non-aqueous electrolyte, the viscosity a of the non-aqueous electrolyte, and the mass percentage content w of the compound represented by Structural Formula 1 further meet the above conditions, the deintercalation ability of the lithium-ion battery in the negative electrode active material layer in the non-aqueous electrolyte can be further improved, thereby improving the ionic conductivity and capacity retention rate.

[0047] In a specific embodiment, the surface tension F of the non-aqueous electrolyte can be 5 N / m, 8 N / m, 9 N / m, 10 N / m, 12 N / m, 14 N / m, 17 N / m, 19 N / m, 21 N / m, 22 N / m, 24 N / m, 27 N / m, 29 N / m, 31 N / m, 33 N / m, 35 N / m, 37 N / m, 39 N / m, 41 N / m, 42 N / m, 44 N / m, 47 N / m or 50 N / m.

[0048] In a preferred embodiment, the surface tension F of the non-aqueous electrolyte is 15-40 N / m.

[0049] The surface tension F of the non-aqueous electrolyte can be tested by a platinum ring method, and the test standard refers to GB / T5549-2010.

[0050] The surface tension F of the non-aqueous electrolyte determines the cohesive force on the surface of the non-aqueous electrolyte. The greater the surface tension, the greater the cohesive force. The surface tension F of the non-aqueous electrolyte is affected by the ion concentration, non-aqueous organic solvent, and additives therein. When the surface tension F of the non-aqueous electrolyte is within the above range, it is beneficial to improve the uniformity of the non-aqueous electrolyte in the battery body, avoid the occurrence of incomplete interfacial lithium insertion, improve the stability of the battery, and extend the service life.

[0051] In a specific embodiment, the viscosity a of the non-aqueous electrolyte at 25°C is 2mPa.s, 2.2mPa.s, 2.5mPa.s, 2.8mPa.s, 3mPa.s, 3.2mPa.s, 3.5mPa.s, 3.8mPa.s, 4mPa.s, 4.8mPa.s, 5.0mPa.s, 5.4mPa.s, 5.8mPa.s, 6.0mPa.s, 6.9mPa.s, 7.2mPa.s, 8.0mPa.s, 8.5mPa.s, 9.3mPa.s, 9.6mPa.s or 10mPa.s.

[0052] In a preferred embodiment, the viscosity a of the non-aqueous electrolyte at 25° C. is 2.5 to 7 mPa.s.

[0053] The viscosity a of the non-aqueous electrolyte directly affects its fluidity. The viscosity of the non-aqueous electrolyte is greatly affected by the non-aqueous organic solvent in the electrolyte, and is also affected by the selection and content of the additives and electrolyte salts in the electrolyte. If the viscosity of the non-aqueous electrolyte is too high, the electrolyte fluidity will deteriorate, which will in turn affect the migration of lithium ions and effective additives in the battery, causing concentration polarization at the positive and negative terminals of the electrolyte, affecting the battery's high-rate charging performance and cycle performance capacity retention rate. If the viscosity of the non-aqueous electrolyte is too low, the non-aqueous electrolyte's liquid retention coefficient in the battery is too low, which can easily cause the battery to become depleted and affect the battery's cycle performance.

[0054] In a specific embodiment, the mass percentage content w of the compound represented by structural formula 1 in the non-aqueous electrolyte can be 0.5%, 1%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.5%, 4.8% or 5.0%.

[0055] In a preferred embodiment, the mass percentage content w of the compound represented by structural formula 1 in the non-aqueous electrolyte is 0.8% to 3%.

[0056] The compound represented by Structural Formula 1 has a very weak polarity and can adjust the polarity of the electrolyte fluid, change the surface composition of the liquid, change the cohesive force of the liquid surface, and thus affect the surface tension of the non-aqueous electrolyte itself. During the battery cycle, the enhanced diffusion capacity of the electrolyte can achieve rapid replenishment of local additives, avoiding failure caused by local additive consumption and inability to replenish in time, effectively improving the battery cycle efficiency. At the same time, the structure of the compound represented by Structural Formula 1 has a large difference in polarity from the solvent system, which changes the relative fluidity of the non-aqueous electrolyte body and affects the viscosity of the non-aqueous electrolyte. If the viscosity a of the non-aqueous electrolyte is too high, it will affect the fluidity of the electrolyte, thereby affecting the migration rate of Li ions during the cycle and adversely affecting the rate performance of the battery. Therefore, the actual performance of the compound represented by Structural Formula 1 is affected by the surface tension and viscosity of the non-aqueous electrolyte itself. If the content w of the compound represented by Structural Formula 1 is insufficient, the diffusion capacity of the non-aqueous electrolyte on the electrode surface is limited, and the performance improvement of the battery is limited. If the content w of the compound represented by Structural Formula 1 is excessive, the viscosity of the electrolyte will be too high, affecting the battery cycle rate performance and formation effect.

[0057] In some preferred embodiments, the compound represented by Structural Formula 1 has a symmetrical structure.

[0058] In the description of the present invention, the term "symmetrical structure" means that the specific structural formula of the compound shown in Structural Formula 1 can form a symmetrical structure based on a certain symmetry axis. As an example: Compounds 1 to 16 are symmetrical structures, and Compound 17 is an asymmetrical structure.

[0059] Compared to asymmetric structures, compounds represented by Formula 1, which have symmetrical structures, are more effective in reducing the overall polarity of the compound, thereby regulating the polarity of the non-aqueous electrolyte fluid, changing the electrolyte's solvation structure and surface molecular composition, altering the cohesive force of the liquid surface, and improving the electrolyte's ability to diffuse across the electrode. This enhanced electrolyte diffusion allows for rapid localized additive replenishment, preventing failure due to localized additive depletion and inability to replenish in a timely manner.

[0060] In some preferred embodiments, the compound shown in Structural Formula 1 does not contain halogen atoms, which is beneficial to further reduce the overall polarity of the compound, improve the diffusion ability of the electrolyte on the electrode, avoid failure caused by local additive consumption and inability to replenish in time, and improve the cycle life of the battery.

[0061] In some preferred embodiments, the R1 is selected from C1 to C8 alkyl groups.

[0062] In some preferred embodiments, the R1 includes methyl, ethyl, propyl, butyl, isopropyl, isobutyl, tert-butyl, isopentyl, ethynyl, and aryl.

[0063] In some preferred embodiments, n is selected from integers of 3 to 4. The compound represented by the structural formula 1 is a cycloalkane with a branched chain and 5-6 carbon atoms, and has higher stability.

[0064] In some embodiments, the compound represented by Structural Formula 1 includes one or more of the following compounds:

[0065] In some embodiments, the electrolyte salt includes LiPF6, LiTFSI, LiBOB, LiDFOB, LiDFOP, LiPO2F2, LiBF4, LiSbF6, LiAsF6, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiClO4, LiAlCl4, LiCF3SO3, LiSO3F, Li2B 10 Cl 10 , lithium chloroborane, lithium tetrafluorooxalophosphate, lithium trioxalophosphate, a lower aliphatic carboxylic acid lithium having 4 or less carbon atoms, or at least one lithium salt of lithium tetraphenylborate.

[0066] In some embodiments, the concentration of the lithium salt in the non-aqueous electrolyte is 0.1 mol / L to 4 mol / L. In a preferred embodiment, the concentration of the lithium salt in the non-aqueous electrolyte is 0.5 mol / L to 2.5 mol / L. Specifically, in the non-aqueous electrolyte, the concentration of the lithium salt may be 0.5 mol / L, 0.55 mol / L, 0.6 mol / L, 0.65 mol / L, 0.7 mol / L, 0.8 mol / L, 0.85 mol / L, 0.9 mol / L, 0.95 mol / L, 1.0 mol / L, 1.1 mol / L, 1.15 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.45 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2.0 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L or 2.5 mol / L.

[0067] In some embodiments, based on the total mass of the non-aqueous electrolyte being 100%, the mass content of the non-aqueous organic solvent is 65% to 90%.

[0068] Specifically, based on the total mass of the non-aqueous electrolyte as 100%, the mass content of the non-aqueous organic solvent can be 65%, 68%, 71%, 74%, 76%, 78%, 79%, 80%, 81.5%, 82%, 84%, 85%, 86%, 87%, 89%, or 90%.

[0069] In some embodiments, the non-aqueous organic solvent includes at least one of an ether solvent, a nitrile solvent, a carbonate solvent, a carboxylate solvent, and a sulfone solvent.

[0070] In some embodiments, the ether solvent includes a cyclic ether or a chain ether, preferably a chain ether with 3 to 10 carbon atoms and a cyclic ether with 3 to 6 carbon atoms. The cyclic ether may be, but is not limited to, at least one of 1,3-dioxolane (DOL), 1,4-dioxolane (DX), a crown ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-CH3-THF), and 2-trifluoromethyltetrahydrofuran (2-CF3-THF). The chain ether may be, but is not limited to, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether. Because chain ethers have high solvation ability with lithium ions and can improve ion dissociation, dimethoxymethane, diethoxymethane, and ethoxymethoxymethane are particularly preferred because they have low viscosity and can impart high ionic conductivity. The ether compound may be used alone or in any combination and ratio. The amount of the ether compound added is not particularly limited and is any amount that does not significantly impair the effects of the high-density lithium-ion battery of the present invention. The amount is typically 1% or more by volume, preferably 2% or more by volume, and more preferably 3% or more by volume, based on 100% by volume of the non-aqueous solvent. Furthermore, the amount is typically 30% or less by volume, preferably 25% or less by volume, and more preferably 20% or less by volume.

[0071] In some embodiments, the nitrile solvent may be, but is not limited to, at least one of acetonitrile, glutaronitrile, and malononitrile.

[0072] In some embodiments, the carbonate solvent includes a cyclic carbonate or a chain carbonate. The cyclic carbonate can be, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (GBL), and butylene carbonate (BC); the chain carbonate can be, but is not limited to, at least one of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and dipropyl carbonate (DPC). The content of the cyclic carbonate is not particularly limited and is arbitrary within the range that does not significantly damage the effect of the lithium-ion battery of the present invention. However, when using one alone, the lower limit of its content is generally 3% or more by volume, preferably 5% or more by volume, relative to the total amount of solvent in the non-aqueous electrolyte. By setting this range, the decrease in conductivity due to the decrease in the dielectric constant of the non-aqueous electrolyte can be avoided, and it is easy to achieve a good range of high current discharge characteristics, stability relative to the negative electrode, and cycle characteristics of the non-aqueous electrolyte battery. In addition, the upper limit is generally 90% or less by volume, preferably 85% or less by volume, and more preferably 80% or less by volume. By setting this scope, the oxidation / reduction tolerance of nonaqueous electrolyte can be improved, thereby contributing to the stability during high temperature storage. The content of linear carbonate is not particularly limited, and relative to the total amount of solvent of nonaqueous electrolyte, is usually more than 15% by volume, preferably more than 20% by volume, and more preferably more than 25% by volume. In addition, usually the volume ratio is less than 90%, preferably less than 85% by volume, and more preferably less than 80% by volume. By making the content of linear carbonate in the above-mentioned scope, it is easy to make the viscosity of nonaqueous electrolyte reach appropriate range, suppress the reduction of ionic conductivity, and then contribute to the output characteristics of nonaqueous electrolyte battery reach good scope. When using two or more linear carbonates in combination, make the total amount of linear carbonate meet the above-mentioned scope.

[0073] In certain embodiments, also can preferably use the linear carbonates with fluorine atoms (hereinafter referred to as " fluorinated linear carbonate ").The number of the fluorine atoms possessed by fluorinated linear carbonate is as long as being more than 1 then has no particular restrictions, but is generally below 6, preferably below 4.When fluorinated linear carbonate has a plurality of fluorine atoms, these fluorine atoms can be bonded on the same carbon, also can be bonded on different carbons.As fluorinated linear carbonate, can enumerate, fluorinated dimethyl carbonate derivatives, fluorinated ethyl methyl carbonate derivatives, fluorinated diethyl carbonate derivatives etc.

[0074] Carboxylate solvents include cyclic carboxylates and / or chain carbonates. Examples of cyclic carboxylates include at least one of γ-butyrolactone, γ-valerolactone, and δ-valerolactone. Examples of chain carbonates include at least one of methyl acetate (MA), ethyl acetate (EA), propyl acetate (EP), butyl acetate, propyl propionate (PP), and butyl propionate.

[0075] In some embodiments, the sulfone solvent includes a cyclic sulfone and a chain sulfone. Preferably, in the case of a cyclic sulfone, the compound generally has 3 to 6 carbon atoms, preferably 3 to 5 carbon atoms; in the case of a chain sulfone, the compound generally has 2 to 6 carbon atoms, preferably 2 to 5 carbon atoms. There is no particular limitation on the amount of sulfone solvent added, and it can be any amount that does not significantly impair the effect of the lithium-ion battery of the present invention. The volume ratio relative to the total amount of solvent in the non-aqueous electrolyte is generally 0.3% or more, preferably 0.5% or more, and more preferably 1% or more. Furthermore, the volume ratio is generally 40% or less, preferably 35% or less, and more preferably 30% or less. When two or more sulfone solvents are used in combination, the total amount of the sulfone solvents can be adjusted to meet the above range. When the amount of sulfone solvent added is within the above range, a non-aqueous electrolyte with excellent high-temperature storage stability tends to be obtained.

[0076] In a preferred embodiment, the non-aqueous organic solvent comprises a mixture of cyclic carbonate and chain carbonate.

[0077] In some embodiments, the additive further comprises at least one of a cyclic sulfate compound, a sultone compound, a cyclic carbonate compound, a phosphate compound, a borate compound, and a nitrile compound.

[0078] In some embodiments, based on the total mass of the non-aqueous electrolyte being 100%, the content of the additive is 0.01% to 10%.

[0079] In some embodiments, the cyclic sulfate ester compound includes at least one of vinyl sulfate, propylene sulfate, and methyl vinyl sulfate.

[0080] In some embodiments, the sultone compound includes at least one of 1,3-propane sultone, 1,4-butane sultone, and 1,3-propene sultone.

[0081] In some embodiments, the cyclic carbonate compound includes at least one of vinylene carbonate, ethylene carbonate, methylene carbonate, fluoroethylene carbonate, trifluoromethylethylene carbonate, bisfluoroethylene carbonate, or the compound shown in Structural Formula 2:

[0082] In the structural formula 2, R 21 、R 22 、R 23 、R 24 、R 25 、R 26 Each is independently selected from a hydrogen atom, a halogen atom, and a C1-C5 group.

[0083] In some embodiments, the phosphate compound includes at least one of tris(trimethylsilyl)phosphate, tris(triethylsilyl)phosphate, or a compound represented by formula 3:

[0084] In the structural formula 3, R 31 、R 32 、R 33 Each independently selected from C1-C5 saturated hydrocarbon group, C1-C5 unsaturated hydrocarbon group, C1-C5 halogenated hydrocarbon group, -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and R 31 、R 32 、R 33 At least one of them is an unsaturated hydrocarbon group.

[0085] In a preferred embodiment, the phosphate compound shown in Structural Formula 2 may be at least one of tripropargyl phosphate, dipropargyl methyl phosphate, dipropargyl ethyl phosphate, dipropargyl propyl phosphate, dipropargyl trifluoromethyl phosphate, dipropargyl-2,2,2-trifluoroethyl phosphate, dipropargyl-3,3,3-trifluoropropyl phosphate, dipropargyl hexafluoroisopropyl phosphate, triallyl phosphate, diallyl methyl phosphate, diallyl ethyl phosphate, diallyl propyl phosphate, diallyl trifluoromethyl phosphate, diallyl-2,2,2-trifluoroethyl phosphate, diallyl-3,3,3-trifluoropropyl phosphate, and diallyl hexafluoroisopropyl phosphate.

[0086] In some embodiments, the borate compound includes at least one of tris(trimethylsilyl)borate and tris(triethylsilyl)borate.

[0087] In some embodiments, the nitrile compound includes at least one of succinonitrile, glutaronitrile, ethylene glycol bis(propionitrile) ether, hexanetrionitrile, adiponitrile, pimelonitrile, suberonitrile, azelaic acid dinitrile, and sebaconitrile.

[0088] In other embodiments, the additives may also include other additives that can improve battery performance: for example, additives that enhance battery safety, such as flame retardant additives such as fluorophosphates and cyclophosphazenes, or overcharge prevention additives such as tert-amylbenzene and tert-butylbenzene.

[0089] It should be noted that, unless otherwise specified, under normal circumstances, the content of any one of the optional substances in the additives in the non-aqueous electrolyte is less than 10%, preferably, the content is 0.01-5%, and more preferably, the content is 0.1% to 2%. Specifically, the content of any one of the optional substances in the additives can be 0.01%, 0.05%, 0.08%, 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 7.8%, 8%, 8.5%, 9%, 9.5%, or 10%.

[0090] In some embodiments, the additive includes fluoroethylene carbonate, and based on the total mass of the non-aqueous electrolyte being 100%, the added amount of the fluoroethylene carbonate is 0.01% to 30%.

[0091] Another embodiment of the present invention provides a battery including a positive electrode, a negative electrode, and the non-aqueous electrolyte as described above.

[0092] In some embodiments, the positive electrode includes a positive electrode material layer, the positive electrode material layer includes a positive electrode active material, and the positive electrode active material includes LiFe 1-x’ M' x’ PO4、LiMn 2-y’ M y’ O4 and LiNi x Co y Mn z M 1-x-y-z One or more of O2, wherein M' includes one or more of Mn, Mg, Co, Ni, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V, Nb, Ce, Zr, W or Ti, M includes one or more of Fe, Co, Ni, Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V, Nb, Ce, Zr, W or Ti, and 0≤x'<1, 0≤y'≤1, 0≤y≤1, 0≤x≤1, 0≤z≤1, x+y+z≤1.

[0093] In some embodiments, the positive electrode material layer further includes a positive electrode binder and a positive electrode conductor, and the positive electrode active material, the positive electrode binder and the positive electrode conductor are blended to obtain the positive electrode material layer.

[0094] The positive electrode binder includes polyvinylidene fluoride, a copolymer of vinylidene fluoride, polytetrafluoroethylene, a copolymer of vinylidene fluoride-hexafluoropropylene, a copolymer of tetrafluoroethylene-hexafluoropropylene, a copolymer of tetrafluoroethylene-perfluoroalkyl vinyl ether, a copolymer of ethylene-tetrafluoroethylene, a copolymer of vinylidene fluoride-tetrafluoroethylene, a copolymer of vinylidene fluoride-trifluoroethylene, a copolymer of vinylidene fluoride-trichloroethylene, a copolymer of vinylidene fluoride-fluoroethylene, a copolymer of vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene, thermoplastic polyimide, a thermoplastic resin such as polyethylene and polypropylene; an acrylic resin; and at least one of styrene butadiene rubber.

[0095] The positive electrode conductive agent includes at least one of conductive carbon black, conductive carbon balls, conductive graphite, conductive carbon fibers, carbon nanotubes, graphene, or reduced graphene oxide.

[0096] In some embodiments, the positive electrode current collector includes a metal material that can conduct electrons. Preferably, the positive electrode current collector includes at least one of Al, Ni, tin, copper, and stainless steel. In a more preferred embodiment, the positive electrode current collector is selected from aluminum foil.

[0097] In some embodiments, the negative electrode includes a negative electrode active material layer, and the compaction density of the negative electrode active material layer is 1.5 to 1.8 g / cm 3 Specifically, the compaction density of the negative electrode active material layer is 1.5 g / cm 3 , 1.55g / cm 3 , 1.6g / cm 3 、 1.65g / cm 3 , 1.7g / cm 3 , 1.75g / cm 3 , 1.8g / cm 3 or any range of the above values.

[0098] In some embodiments, the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material includes at least one of a carbon-based negative electrode, a silicon-based negative electrode, a tin-based negative electrode, and a lithium negative electrode. Carbon-based negative electrodes may include graphite, hard carbon, soft carbon, graphene, mesocarbon microbeads, etc.; silicon-based negative electrodes may include silicon materials, silicon oxides, silicon-carbon composites, and silicon alloys; tin-based negative electrodes may include tin, tin-carbon, tin-oxygen, and tin metal compounds; and lithium negative electrodes may include metallic lithium or a lithium alloy. Specifically, the lithium alloy may be at least one of a lithium-silicon alloy, a lithium-sodium alloy, a lithium-potassium alloy, a lithium-aluminum alloy, a lithium-tin alloy, and a lithium-indium alloy.

[0099] In a more preferred embodiment, the negative electrode active material includes at least one of graphite, hard carbon, soft carbon, graphene, and silicon-carbon composite materials.

[0100] In some embodiments, the silicon material is one or more of silicon nanoparticles, silicon nanowires, silicon nanotubes, silicon thin films, 3D porous silicon, and hollow porous silicon.

[0101] In some embodiments, the negative electrode further comprises a negative electrode current collector, and the negative electrode active material layer covers the surface of the negative electrode current collector. The negative electrode current collector comprises an electron-conducting metal material. Preferably, the negative electrode current collector comprises at least one of Al, Ni, tin, copper, and stainless steel. In a more preferred embodiment, the negative electrode current collector is selected from copper foil.

[0102] In some embodiments, the negative electrode active material layer further includes a negative electrode binder and a negative electrode conductive agent. The negative electrode active material, the negative electrode binder, and the negative electrode conductive agent are blended together to form the negative electrode active material layer. The negative electrode binder and the negative electrode conductive agent may be the same as the positive electrode binder and the positive electrode conductive agent, respectively, and are not further described here.

[0103] In some embodiments, the battery further includes a separator, which is located between the positive electrode and the negative electrode.

[0104] The diaphragm can be an existing conventional diaphragm, which can be a ceramic diaphragm, a polymer diaphragm, a non-woven fabric, an inorganic-organic composite diaphragm, etc., including but not limited to single-layer PP (polypropylene), single-layer PE (polyethylene), double-layer PP / PE, double-layer PP / PP and three-layer PP / PE / PP diaphragms.

[0105] The present invention is further described below with reference to the following examples.

[0106] The compounds represented by structural formula 1 involved in the following examples are shown in Table 1:

[0107] Table 1

[0108] Table 2

[0109] Example 1

[0110] This embodiment is used to illustrate the lithium ion battery and its preparation method disclosed in the present invention, including the following steps:

[0111] 1) Preparation of non-aqueous electrolyte:

[0112] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a mass ratio of EC:EMC = 10:90, and then lithium hexafluorophosphate (LiPF6) was added to a molar concentration of 1 mol / L. The compound represented by Structural Formula 1 was then added. Based on the total weight of the non-aqueous electrolyte being 100%, the mass percentage w of the compound represented by Structural Formula 1 in the non-aqueous electrolyte, the surface tension F of the electrolyte, and the viscosity a of the electrolyte are shown in Table 2.

[0113] 2) Preparation of positive plate:

[0114] The positive electrode active material, LiFePO4, conductive carbon black Super-P, and binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 94:3:3 and then dispersed in N-methyl-2-pyrrolidone (NMP) to create a positive electrode slurry. The slurry is evenly coated on both sides of aluminum foil, dried, rolled, and vacuum-dried, and then ultrasonically welded to aluminum lead wires to form the positive electrode plate.

[0115] 3) Preparation of negative plate:

[0116] The negative electrode active material, artificial graphite, conductive carbon black Super-P, and binders styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC), were mixed in a mass ratio of 94:1:2.5:2.5 and then dispersed in deionized water to produce a negative electrode slurry. The slurry was coated on both sides of a copper foil, dried, rolled, and vacuum-dried, and nickel lead wires were welded to it using an ultrasonic welder to produce a negative electrode plate. The compacted density of the negative electrode was 1.7 g / cm 3 .

[0117] 4) Preparation of battery cells:

[0118] A separator is placed between the positive plate and the negative plate, and then the sandwich structure consisting of the positive plate, negative plate and separator is wound. The wound body is flattened and placed in an aluminum foil packaging bag, and vacuum baked at 85°C for 48 hours to obtain a battery cell ready for liquid injection.

[0119] 5) Injection and formation of battery cells:

[0120] In a glove box with a dew point controlled below -40°C, the non-aqueous electrolyte prepared above was injected into the battery cell, vacuum-sealed, and left to stand for 6 hours.

[0121] Then, conventional formation for the first charge was carried out according to the following steps: 0.05C constant current charging for 180 min, 0.1C constant current charging for 120 min, 0.1C constant current charging for 120 min, secondary vacuum sealing, and then further constant current charging at 0.5C to 3.65V, and then constant voltage charging until the current drops to 0.02C. After standing for 5 minutes, the battery was discharged at 0.5C constant current to 3.0V to obtain a LiFePO4 / artificial graphite lithium ion battery.

[0122] Examples 2 to 20

[0123] Examples 2 to 20 are used to illustrate the lithium-ion battery and the preparation method thereof disclosed in the present invention, and include most of the operating steps in Example 1, except that:

[0124] The mass percentage w of the non-aqueous organic solvent and the compound represented by structural formula 1 in the non-aqueous electrolyte in Examples 2 to 20, the surface tension F of the non-aqueous electrolyte, and the viscosity a of the non-aqueous electrolyte are shown in Table 2.

[0125] The compacted density of the negative electrode in Example 18 is 1.5 g / cm 3 ;

[0126] The compacted density of the negative electrode in Example 19 is 1.75 g / cm 3 .

[0127] The compacted density of the negative electrode in Example 20 is 1.8 g / cm 3 .

[0128] Comparative Examples 1 to 18

[0129] Comparative Examples 1 to 18 are used to compare and illustrate the lithium ion battery and preparation method thereof disclosed in the present invention, and include most of the operating steps in Example 1, except that:

[0130] The mass percentage w of the non-aqueous organic solvent and the compound represented by Structural Formula 1 in the non-aqueous electrolyte in Comparative Examples 1 to 18, the surface tension F of the non-aqueous electrolyte, and the viscosity a of the non-aqueous electrolyte are shown in Table 2.

[0131] The compaction density of the negative electrode in Comparative Example 16 is 1.5 g / cm 3 ;

[0132] The compacted density of the negative electrode in Comparative Example 17 is 1.75 g / cm 3 ;

[0133] The compacted density of the negative electrode in Comparative Example 18 is 1.8 g / cm 3 ;

[0134] Performance Testing

[0135] The lithium-ion battery prepared above was subjected to the following performance tests:

[0136] 1. Battery negative electrode surface integrity test (A / B / C)

[0137] The prepared LiFePO4 / artificial graphite lithium-ion batteries were charged at a constant current of 1C to 3.65V, then charged at a constant voltage until the current dropped to 0.02C. The fully charged batteries were disassembled, and the surface integrity of the battery's negative electrode (A / B / C) was determined by the percentage of black spots / blue spots / lithium deposition on the fully charged negative electrode surface. A C rating was assigned if the black spot area accounted for >30% of the battery's negative electrode surface area, a B rating if the black spot area accounted for 2-30% of the battery's negative electrode surface area, and an A rating if the black spot area accounted for <2% of the battery's negative electrode surface area. Figure 1 shows examples of grades A, B, and C.

[0138] 2. Cycle performance test

[0139] Place the lithium-ion battery in a constant temperature environment of 25°C, charge it at a constant current of 1C to 3.65V, then charge it at a constant voltage until the current drops to 0.02C, and then discharge it at a constant current of 2C to 2.5V. Repeat this cycle 1500 times, and record the first discharge capacity and the last discharge capacity.

[0140] The capacity retention rate of the cycle is calculated as follows:

[0141] Capacity retention rate (%) = last discharge capacity / first discharge capacity×100%.

[0142] 3. 60℃ Storage Performance

[0143] At room temperature, the divided battery was charged to 3.65V at 1C, with a cut-off current of 0.02C. After standing for 5 minutes, it was discharged to 2.0V at 0.5C, and the initial capacity was recorded. Then it was charged to 3.65V at 1C constant current and constant voltage, with a cut-off current of 0.02C. After storing the fully charged battery in a constant temperature box at 60℃ for 30 days, it was discharged to 2.0V at 1C, and the capacity was recorded.

[0144] Capacity retention rate (%) = (retention capacity after 30 days of storage / initial capacity) × 100%

[0145] (1) The test results obtained in Examples 1 to 12 and Comparative Examples 1 to 15 are shown in Table 3.

[0146] Table 3

[0147] From the test results of Examples 1 to 12 and Comparative Examples 1 to 15, it can be seen that in a battery system with a high-pressure negative electrode, the compound represented by Structural Formula 1 is added to the non-aqueous electrolyte as an additive, and different non-aqueous organic solvent systems are adjusted so that the surface tension F of the non-aqueous electrolyte, the viscosity a of the non-aqueous electrolyte, and the mass percentage content w of the compound represented by Structural Formula 1 meet the conditions of 0.05≤a*w / F≤3, and 10≤F≤50, 2≤a≤10, and 0.5≤w≤5. The obtained lithium ion battery has good negative electrode surface integrity after charge and discharge cycles, and at the same time The invention has a long cycle life and a high high-temperature storage capacity retention rate. It is speculated that this is because the compound shown in structural formula 1 itself has a weak polarity. When combined with a polar non-aqueous organic solvent, the interfacial polarity of the non-aqueous electrolyte can be adjusted, which can affect the permeability of the non-aqueous electrolyte in the negative electrode material layer. At the same time, the surface tension and viscosity of the non-aqueous electrolyte are regulated, so that the three are in a synergistic state, and ultimately the penetration effect of the non-aqueous electrolyte on the high-density negative electrode is improved, thereby ensuring the uniform deposition of lithium ions in the negative electrode material layer and improving the cycle stability and high-temperature stability of the battery.

[0148] The test results of Examples 1 to 12 show that when the surface tension F of the non-aqueous electrolyte, the viscosity a of the non-aqueous electrolyte, and the mass percentage content w of the compound represented by Structural Formula 1 further satisfy the conditions 0.1≤a*w / F≤0.6, and 15≤F≤40, 2.5≤a≤7, and 0.8≤w≤3, the obtained non-aqueous electrolyte has the best permeability to the negative electrode.

[0149] The test results of Comparative Examples 7 to 12 show that when one or more of the F value, a value, and w value exceeds the limited range of 10≤F≤50, 2≤a≤10, and 0.5≤w≤5, even if the requirement of the relationship 0.05≤a*w / F≤3 is satisfied, the lithium ion deposition uniformity, cycle capacity retention rate, and high-temperature storage capacity retention rate of the obtained lithium ion battery are poor. This indicates that when the surface tension F of the non-aqueous electrolyte, the viscosity a of the non-aqueous electrolyte, and the mass percentage content w of the compound represented by Structural Formula 1 are too high or too low, the permeability of the non-aqueous electrolyte in the high-pressure negative electrode is affected, resulting in uneven deposition of lithium ions, and further leading to a shortened cycle life and a decrease in high-temperature performance of the lithium ion battery. From the test results of Comparative Examples 1 to 6, it can be seen that even if the F value, a value and w value all meet the parameter range limits, if the a*w / F value is too large or too small, it will lead to deterioration of the cycle performance and high-temperature storage performance of the lithium-ion battery. This shows that there is a mutual influence and interaction relationship between the surface tension F of the non-aqueous electrolyte, the viscosity a of the non-aqueous electrolyte and the mass percentage content w of the compound represented by Structural Formula 1. Only when and only when the three reach a good equilibrium state can it be beneficial to improve the permeability of the non-aqueous electrolyte to the negative electrode material layer and avoid the appearance of lithium dendrites and black spots.

[0150] (2) The test results obtained in Example 3 and Examples 13 to 17 are entered in Table 4.

[0151] Table 4

[0152] It can be seen from the test results of Example 3 and Examples 13 to 17 that in the battery system with a high-pressure negative electrode provided by the present invention, when different compounds represented by structural formula 1 are used, and the surface tension F of the non-aqueous electrolyte, the viscosity a of the non-aqueous electrolyte and the mass percentage content w of the compound represented by structural formula 1 satisfy the conditions 0.05≤a*w / F≤3, and 10≤F≤50, 2≤a≤10, 0.5≤w≤5, the effects are similar, and both have an improving effect on the cycle performance and high-temperature storage performance of the lithium-ion battery, and reduce the occurrence of lithium dendrites, indicating that the relationship provided by the present invention is applicable to different compounds represented by structural formula 1.

[0153] The compound represented by Structural Formula 1 in Example 17 has an asymmetric structure. Compared with the compounds represented by Structural Formula 1 with symmetrical structures in other examples, the cycling performance and high-temperature storage performance of the lithium-ion battery are significantly worse. This indicates that the compound represented by Structural Formula 1 with a symmetrical structure is beneficial to reducing the overall polarity of the compound, thereby adjusting the polarity of the fluid of the non-aqueous electrolyte, changing the electrolyte solvation structure and surface molecular composition, changing the cohesive force of the liquid surface, and improving the diffusion ability of the electrolyte in the electrode.

[0154] (3) The test results obtained in Example 3, Examples 18 to 20, Comparative Example 14, and Comparative Examples 16 to 18 are entered in Table 5.

[0155] Table 5

[0156] It can be seen from the test results of Example 3, Examples 18 to 20, Comparative Example 14, and Comparative Examples 16 to 18 that when Comparative Examples 14 and Comparative Examples 16 to 18, which do not meet the conditions of the present invention of 0.05≤a*w / F≤3, and 10≤F≤50, 2≤a≤10, and 0.5≤w≤5, are applied to a negative electrode battery system with a high compaction density, as the negative electrode compaction density increases, the battery cycle capacity retention rate and the high-temperature storage capacity retention rate both show a significant decrease, and black spots also appear. The electrolyte system provided by the present invention can effectively reduce the deterioration of the battery cycle performance and high-temperature storage performance caused by the increase in compaction density, so that the battery can achieve good cycle life and high-temperature stability under high compaction conditions.

[0157] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A non-aqueous electrolyte, characterized in that: It includes a non-aqueous organic solvent, an electrolyte salt and an additive, wherein the additive includes a compound shown in structural formula 1: wherein n is selected from an integer of 2 to 5, and R1 is selected from a C1 to C8 alkyl group, a C2 to C8 alkenyl group, a C2 to C8 alkynyl group, or a C5 to C10 aryl group; The non-aqueous electrolyte meets the following conditions: 0.05≤a*w / F≤3, and 10≤F≤50, 2≤a≤10, 0.5≤w≤5; Wherein, F is the surface tension of the non-aqueous electrolyte, in N / m; a is the viscosity of the non-aqueous electrolyte at 25°C, in mPa.s; w is the mass percentage content of the compound represented by structural formula 1 in the non-aqueous electrolyte, in wt%.

2. The non-aqueous electrolyte according to claim 1, characterized in that The non-aqueous electrolyte satisfies the following condition: 0.1≤a*w / F≤0.

6.

3. The non-aqueous electrolyte according to claim 1, characterized in that The surface tension F of the non-aqueous electrolyte is 15-40 N / m.

4. The non-aqueous electrolyte according to claim 1, characterized in that The viscosity a of the non-aqueous electrolyte at 25° C. is 2.5 to 7 mPa.s.

5. The non-aqueous electrolyte according to claim 1, characterized in that The mass percentage content w of the compound represented by structural formula 1 in the non-aqueous electrolyte is 0.8% to 3%.

6. The non-aqueous electrolyte according to claim 1, characterized in that The compound shown in the structural formula 1 has a symmetrical structure.

7. The non-aqueous electrolyte according to claim 6, characterized in that The compound represented by the structural formula 1 includes one or more of the following compounds:

8. The non-aqueous electrolyte according to claim 1, characterized in that The additive further includes at least one of cyclic sulfate compounds, sultone compounds, cyclic carbonate compounds, phosphate compounds, borate compounds and nitrile compounds.

9. The non-aqueous electrolyte according to claim 8, characterized in that The cyclic sulfate ester compound includes at least one of vinyl sulfate, propylene sulfate and methyl vinyl sulfate.

10. The non-aqueous electrolyte according to claim 8, characterized in that The sultone compound includes at least one of 1,3-propane sultone, 1,4-butane sultone and 1,3-propene sultone.

11. The non-aqueous electrolyte according to claim 8, characterized in that The cyclic carbonate compound includes at least one of vinylene carbonate, ethylene carbonate, methylene carbonate, fluoroethylene carbonate, trifluoromethylethylene carbonate, bisfluoroethylene carbonate or the compound shown in Structural Formula 2: In the structural formula 2, R 21 , R 22 , R 23 , R 24 , R 25 , R 26 Each is independently selected from a hydrogen atom, a halogen atom, and a C1-C5 group.

12. The non-aqueous electrolyte according to claim 8, characterized in that The phosphate compound includes at least one of tris(trimethylsilyl)phosphate, tris(triethylsilyl)phosphate or the compound shown in structural formula 3: In the structural formula 3, R 31 , R 32 , R 33 Each is independently selected from a C1-C5 saturated hydrocarbon group, a C1-C5 unsaturated hydrocarbon group, a C1-C5 halogenated hydrocarbon group, -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and R 31 , R 32 , R 33 At least one of them is an unsaturated hydrocarbon group.

13. The non-aqueous electrolyte according to claim 8, characterized in that The borate ester compound includes at least one of tris(trimethylsilyl)borate and tris(triethylsilyl)borate.

14. The non-aqueous electrolyte according to claim 8, characterized in that The nitrile compound includes at least one of succinonitrile, glutaronitrile, ethylene glycol bis(propionitrile) ether, hexanetrinitrile, adiponitrile, pimelonitrile, suberonitrile, azelaic acid dinitrile and sebaconitrile.

15. A battery, characterized in that: The invention comprises a positive electrode, a negative electrode and the non-aqueous electrolyte according to any one of claims 1 to 14.

16. The battery according to claim 15, characterized in that The negative electrode comprises a negative electrode active material layer, and the compaction density of the negative electrode active material layer is 1.5 to 1.8 g / cm 3 .

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