Composite electrolyte and lithium battery

Abstract

The invention discloses a composite electrolyte and a lithium battery. The composite electrolyte comprises a first lithium salt and a composite solvent, wherein the composite solvent contains ethylene glycol dimethyl ether (DME) and / or 1, 3-dioxolame (DOL) and a fluorine-containing ether compound, and the molar ratio of the total of the DME and the DOL to the fluorine-containing ether compound is 1: (0.2-10); the fluorine-containing ether compound is shown as a formula R1-O-R2 in the specification; in the formula, R1 is a fluorinated alkyl group or a fluorinated alkoxy alkyl group of C1-C10, and R2 is an alkyl group or an alkoxy alkyl group of any fluorinated C1-C5. According to the composite electrolyte, the number of cycles and the charge-discharge rate of the lithium metal battery can be remarkably improved, and the performance and the safety of the battery are improved.

Description

Technical Field

[0001] The invention relates to a novel composite electrolyte particularly suitable for lithium metal batteries and application thereof, as well as a lithium battery containing the composite electrolyte. Background Art

[0002] Lithium metal battery is a battery with lithium metal as negative electrode material. As a high energy density battery, it is widely used in electric vehicles, portable electronic devices and energy storage systems. Its high energy density, lightweight and environmentally friendly characteristics make it a hot spot for research and development. The working principle of lithium metal battery is that lithium ions are deposited on the lithium metal negative electrode during charging, migrate to the positive electrode through the intermediate membrane, and migrate back to the positive electrode during discharge. The advantages of lithium metal batteries include high energy density and high voltage platform. However, there are some technical difficulties in the cyclic charging and discharging process of traditional lithium metal batteries. One of the most important problems is the growth and accumulation of lithium dendrites. As lithium ions are continuously inserted and removed during charging and discharging, lithium dendrites are easily formed on the surface of the lithium electrode, and gradually expand to form a lithium dendrite tree structure, resulting in reduced battery safety and reduced cycle life. This phenomenon is usually called the "lithium dendrite problem."

[0003] In order to solve the problem of lithium dendrites, current research is mainly focused on optimizing the electrolyte formulation, changing the structure of battery electrodes and using artificial coatings. However, there are still some limitations in the existing technology: a) Additive limitations: Although many additives have been introduced to inhibit the formation of lithium dendrites, the action mechanism and effect of different additives are still unclear, and the types and proportions of additives are limited. b) Difficulty in solvent selection: It is still challenging to select suitable organic solvents to improve the solubility and electrochemical properties of the electrolyte because the effects of different solvents on battery performance are complex and diverse. c) Limited choice of lithium salts: Lithium salts are the main component of the electrolyte. Different lithium salts have different effects on battery performance, but there is still a lack of more new lithium salts to choose from.

[0004] In summary, although some progress has been made in the research of electrolytes for lithium metal batteries, there are still certain limitations in solving the problem of lithium dendrites, and more in-depth research and innovation are needed. Summary of the invention

[0005] The present invention aims to solve the problem of lithium dendrites existing in the cyclic charge and discharge process of lithium metal batteries, and provide a new electrolyte formula to effectively inhibit the generation and accumulation of lithium dendrites, thereby significantly improving the number of cycles and charge and discharge rates of lithium metal batteries, and improving battery performance and safety.

[0006] The generation and accumulation of lithium dendrites can easily lead to the following problems: (1) Reduced safety: Uneven deposition of lithium ions can easily lead to the generation of lithium dendrites; (2) Reduced cycle life: The continuous consumption of lithium metal will reduce the number of cycles that the battery can be used, thereby reducing the battery's service life; (3) Degraded battery performance: The reaction between lithium metal and conventional electrolyte will affect the battery's charge and discharge efficiency, causing the battery's coulombic efficiency to continue to decrease, thereby reducing the battery's performance.

[0007] In view of the above, the inventors of the present invention have discovered through in-depth research that by selecting a new organic solvent and reasonably choosing the combination ratio of the organic solvent, lithium salt and specific additives, the cycle number and charge and discharge rate of the lithium metal battery can be significantly improved, thereby further promoting the development of lithium metal battery technology.

[0008] Thus, the present invention provides, in one aspect, a composite electrolyte comprising a first lithium salt and a composite solvent; The composite solvent comprises ethylene glycol dimethyl ether (DME) and / or 1,3-dioxolane (DOL), and a fluorine-containing ether compound, and the molar ratio of the total of DME and DOL to the fluorine-containing ether compound is 1:0.2-10; The fluorine-containing ether compound is represented by the formula R1-O-R2; In the formula, R1 is a C1-C10 fluorinated alkyl group or a fluorinated alkoxyalkyl group, and R2 is an arbitrarily fluorinated C1-C5 alkyl group or an alkoxyalkyl group.

[0009] In some embodiments of the present invention, R1 is such as -C n1 F m1 H (2*n1+1-m1) or -C n1 O x1 F m1 H (2*n1+1-m1) As shown in the formula, n1 represents the number of carbon atoms in the R1 group, and is an integer of 1-10, preferably 3-7, and more preferably 3-5; m1 represents the number of fluorine atoms substituted in the R1 group, and is an integer of 3-21, preferably 7-15, and more preferably 7-11; x1 represents the number of alkoxy substitutions of R1 as a fluoroalkoxyalkyl group, and is an integer of 1-3, preferably 1 or 2.

[0010] In some embodiments of the present invention, R2 is such as -C n2 H (2*n2+1) or -C n2 F m2 H (2*n2+1-m2) , or -C n2 O x2 H (2*n2+1) or -C n2 O x2 Fm2 H (2*n2+1-m2) As shown in the formula, n2 represents the number of carbon atoms in the R2 group, and is an integer of 1-5, preferably 1-3; m2 represents the number of fluorine atoms substituted in the R2 group, and is an integer of 0-11, preferably 0-7; x2 represents the number of alkoxy substitutions of R1 as a fluoroalkoxyalkyl group, and is an integer of 1-3, preferably 1 or 2.

[0011] In some embodiments of the present invention, the fluorine-containing ether compound is one or more of perfluoropropyl methyl ether, perfluoroisobutyl methyl ether, perfluoro-n-butyl methyl ether, perfluoropentyl methyl ether, perfluorohexyl methyl ether, perfluoro-3-oxabutyl methyl ether, perfluoro-3,5-dioxahexyl methyl ether, perfluoro-2-oxahexyl methyl ether, ethyl perfluorobutyl ether, perfluorodimethyl ether, perfluoromethyl perfluoroethyl ether, perfluoromethyl perfluoropropyl ether, perfluoromethyl perfluorobutyl ether, perfluoroethyl methyl ether, perfluoroethyl ethyl ether, perfluoroethyl propyl ether, perfluoroethyl butyl ether, perfluoropropyl butyl ether, perfluorobutyl butyl ether, perfluoro-3,5-dioxahexyl methyl ether, perfluoro-3-oxabutyl methyl ether, and perfluoro-2-oxahexyl methyl ether.

[0012] In some embodiments of the present invention, the fluorine-containing ether compound is one or more of perfluoropropyl methyl ether, perfluoroisobutyl methyl ether, ethyl perfluorobutyl ether and perfluoroethylpropyl ether.

[0013] In some embodiments of the present invention, the fluorine-containing ether compound is perfluoropropyl methyl ether and / or perfluoroisobutyl methyl ether.

[0014] In some embodiments of the present invention, the first lithium salt is selected from one or more of lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate (LiAsF6), lithium fluorosulfonate (LiFSO3), lithium hexafluoroaluminate (LiAlF6), lithium tetrafluoroborate (LiBF4), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiCF3SO3), lithium tetrafluoroborate (LiBF4) and lithium bis(fluorosulfonyl)imide (LiFSI).

[0015] In some embodiments of the present invention, the composite electrolyte further comprises a second lithium salt and / or an additive.

[0016] Preferably, the second lithium salt is selected from one or more of lithium nitrate (LiNO3), lithium difluorooxalatoborate (LiDFOB), and lithium bis(oxalateborate) (LiBOB).

[0017] Preferably, the additive is selected from one or more of fluoroethylene carbonate (FEC), vinylene carbonate (VC), succinonitrile (SN), methylene methanedisulfonate (MMDS), 1,3-propane sultone (PS), propenyl-1,3-sultone (PST), and dithiodiphenylamine (DTD).

[0018] In some embodiments of the present invention, in the composite electrolyte, the content of the first lithium salt is 0.5-4.5M, preferably 0.7-3M.

[0019] In some embodiments of the present invention, in the composite electrolyte, the content of the second lithium salt is 0.5-5 wt %, preferably 0.7-3 wt %.

[0020] In some embodiments of the present invention, the molar ratio of the total of DME and DOL to the fluorine-containing ether compound in the composite solvent is 1:1-10, preferably 1:1-5, and more preferably 1:1.8-2.8.

[0021] In some embodiments of the present invention, the volume ratio of DME to DOL in the composite solvent is 1:0.1-10, preferably 1:0.3-5.3, and more preferably 1:0.6-1.6.

[0022] In some embodiments of the present invention, the composite solvent is composed of ethylene glycol dimethyl ether (DME), 1,3-dioxolane (DOL) and a fluorine-containing ether compound.

[0023] The second aspect of the present invention provides the use of the composite electrolyte according to the first aspect of the present invention in a lithium battery.

[0024] In some embodiments of the present invention, the lithium battery is a lithium metal battery, a lithium ion battery, a lithium sulfur battery or a lithium air battery.

[0025] The third aspect of the present invention provides a lithium battery, which includes a negative electrode, an electrolyte, a separator, and a positive electrode; wherein the electrolyte is the composite electrolyte of the first aspect of the present invention.

[0026] In some embodiments of the present invention, the lithium battery is a lithium metal battery, a lithium ion battery, a lithium sulfur battery or a lithium air battery.

[0027] Advantageous Effects of the Invention The composite electrolyte of the present invention has the following technical effects and beneficial effects: (1) Significantly improve the number of cycles: The new composite electrolyte of the present invention can promote the uniform deposition of lithium metal, thereby significantly improving the number of cycles of lithium metal batteries. By enhancing the cycle life of the battery, this technology will make lithium metal batteries more durable and reliable, reduce the frequency of battery replacement, and reduce the cost of use.

[0028] (2) Improving the charge and discharge rate: The novel composite electrolyte of the present invention can improve the charge and discharge efficiency of the battery, enabling the lithium metal battery to achieve high-rate transmission faster during the charge and discharge process. This will enable lithium metal batteries to perform better in high charge and discharge rate usage scenarios, meeting the demand for high power output, such as the acceleration performance of electric vehicles and the rapid discharge requirements of energy storage systems.

[0029] (3) Improving battery safety: The novel composite electrolyte of the present invention can effectively inhibit the formation and accumulation of lithium dendrites, reduce the risk of internal short circuits in the battery, and thus improve the safety of lithium metal batteries. In addition, the composite electrolyte is non-flammable and has a high safety factor. More reliable battery safety will reduce the probability of accidents during battery use and protect the safety of users and equipment.

[0030] (4) Promote high energy density applications: Since lithium metal batteries have the characteristics of high energy density, the technology of this invention will promote the development of lithium metal batteries in high energy density application fields. This will have a positive impact on electric vehicles, aerospace, energy storage systems and other fields, and promote the innovation and development of related industries.

[0031] (5) Expanding the application prospects of lithium metal batteries: By improving the cycle performance, power output and safety of lithium metal batteries, new electrolytes will create more opportunities for lithium metal batteries to play a role in a wider range of application scenarios. This will further promote the application expansion of lithium metal battery technology and provide more reliable solutions for future energy storage and mobile applications.

[0032] In summary, the composite electrolyte of the present invention has significant technical effects and beneficial effects in terms of the cycle performance, power output and safety of lithium metal batteries, and is of great significance to promoting the development and application of lithium metal battery technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The impedance data of the batteries assembled from the composite electrolytes of formulation A and formulation B are shown.

[0034] Figure 2 The figures show the cycle performance data of batteries assembled from composite electrolytes of formulation A and formulation B at room temperature.

[0035] Figure 3The figure shows the rate performance data of batteries assembled from composite electrolytes of formulation A and formulation B at room temperature.

[0036] Figure 4 The impedance data of batteries assembled from composite electrolytes of formulation A, formulation C and formulation D are shown.

[0037] Figure 5 The impedance data of batteries assembled from composite electrolytes of formulation A and formulation E are shown. DETAILED DESCRIPTION

[0038] The present invention is further described below by means of specific embodiments. Unless otherwise specified, the academic terms used herein have the same meanings as those generally understood by those of ordinary skill in the art.

[0039] As used herein, the term "alkyl" refers to a straight or branched saturated hydrocarbon group. In some embodiments, C1-C5 alkyl includes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, etc. In some embodiments, the alkyl of the present invention can be C1-C4 alkyl, C1-C3 alkyl, C1-C2 alkyl, C2-C5 alkyl, C2-C4 alkyl, C2-C3 alkyl, C3-C5 alkyl, C3-C4 alkyl or C4-C5 alkyl.

[0040] As used herein, the term "fluoroalkyl" refers to a fluorine-substituted straight or branched saturated hydrocarbon group. In some embodiments, C1-C10 fluoroalkyl includes fluorinated methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, hexyl, heptyl, octyl, nonyl or decyl, etc. In some embodiments, the number of fluorine atoms in the fluoroalkyl group of the present invention is preferably 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, etc.; the specific number of fluorine atoms can be 1, 2, 3, 4, 5, 6, 7, ... 2n-1, 2n, 2n+1, etc., where n is the number of carbon atoms in the fluoroalkyl group. In some embodiments, the number of hydrogen atoms in the fluoroalkyl group of the present invention is preferably 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or 0.

[0041] As used herein, the term "alkoxyalkyl" refers to an alkyl group substituted with an alkoxy group, such as methoxymethyl, methoxyethyl, ethoxyethyl, etc. In the present invention, the number of carbon atoms of the alkoxyalkyl group refers to the total number of carbon atoms in the alkoxyalkyl group. In the present invention, "fluoroalkoxyalkyl" refers to an alkoxyalkyl group substituted with fluorine.

[0042] In the present invention, "optionally fluorinated" means that fluorine substitution may or may not be contained.

[0043] Numerical limits or ranges stated herein are inclusive of the endpoints and specifically include all values ​​and sub-ranges within the numerical limits or ranges.

[0044] Existing ether electrolytes have some disadvantages in lithium metal batteries, specifically in the following aspects. (1) Safety risks: Ether electrolytes have a low flash point and flammability. This means that ether electrolytes may cause fire or explosion when exposed to external heat sources or internal short circuits in the battery. This poses a potential risk to the reliability and safety of lithium metal batteries. (2) Oxidation: Ether electrolytes are easily oxidized under high voltage conditions, which in turn causes thermal runaway and safety problems in the battery. This also limits the reliability and stability of ether electrolytes in applications with high energy density requirements. (3) Evaporation and volatility: Ether electrolytes generally have a high evaporation rate and volatility. During battery cycling and long-term use, electrolyte evaporation can lead to battery capacity loss and changes in electrolyte concentration, thereby reducing battery performance and cycle life. (4) Solubility limitations: Some ether solvents may react with lithium metal and dissolve, resulting in electrolyte loss and lithium metal desolvation. This may lead to battery capacity decay, shortened cycle life, and unstable battery performance. (5) Temperature dependence: The conductivity of ether electrolytes is generally low at low temperatures, which affects the performance and usability of the battery. Under extreme low temperature conditions, ether electrolytes may freeze, causing the battery to not work properly. (6) Intolerant to wide voltage environments: Commonly used ethers include ethylene glycol dimethyl ether (DME) and 1,3-dioxolane (DOL).

[0045] In view of the above problems, the inventors of the present invention have found that a composite electrolyte including a fluorinated ether compound forms a solid electrolyte interface film (SEI film) rich in lithium fluoride on the surface of the lithium metal negative electrode. Among them, lithium fluoride can help Li + It is uniformly deposited on the surface of the lithium metal negative electrode to form an ordered, neatly arranged cylindrical structure, which improves the coulombic efficiency and cycle stability of the lithium metal battery. The SEI film rich in lithium fluoride effectively inhibits the growth of lithium dendrites and the oxidation of the battery positive electrode in the electrolyte, significantly improving the cycle stability and safety of the lithium metal battery and improving the electrochemical performance of the lithium metal battery.

[0046] Specifically, the composite electrolyte of the present invention uses DME and / or DOL as a base solvent, adds a fluorinated ether compound to form a composite solvent, and then combines it with a lithium salt, thereby effectively improving the number of cycles and charge and discharge rates of lithium metal batteries, and overall improving the comprehensive performance of lithium metal batteries such as cycle performance, power output and safety.

[0047] As described above, the first aspect of the present invention provides a composite electrolyte, which comprises a composite lithium salt and a composite solvent; the composite solvent comprises ethylene glycol dimethyl ether (DME) and / or 1,3-dioxolane (DOL), and a fluorinated ether compound, and the molar ratio of the total of DME and DOL to the fluorinated ether compound is 1:0.2-10; the fluorinated ether compound is represented by the formula R1-O-R2; wherein R1 is a C1-C10 fluorinated alkyl or fluorinated alkoxyalkyl, and R2 is an arbitrarily fluorinated C1-C5 alkyl or alkoxyalkyl.

[0048] According to the present invention, by using the fluorinated ether compound of the present invention, a composite electrolyte capable of improving the cycle performance, power output and safety of a lithium battery is provided.

[0049] In the composite electrolyte of the present invention, the ratio of DME to DOL can be any ratio. In some embodiments, only DME and fluorinated ether compounds can be used, or only DOL and fluorinated ether compounds can be used. The properties of the two materials DME and DOL are relatively similar, and their usage ratio can be determined according to the physical properties (such as viscosity, etc.) required for the composite electrolyte. For example, the volume ratio of DME to DOL in the composite solvent can be 1:0.1-10, 1:0.3-5.3 or 1:0.5-5, such as 1:0.5, 1:1, 1:2, 1:3, 1:4 or 1:5.

[0050] In the present invention, R1 is preferably a fluorinated alkyl group with a branch, such as fluorinated isopropyl, fluorinated isobutyl, fluorinated isopentyl, etc., and more preferably the branch is a perfluoroalkyl group. In the present invention, R2 is preferably an arbitrarily fluorinated alkyl group or alkoxyalkyl group with a branch, and more preferably the branch is a perfluoroalkyl group.

[0051] In the present invention, R1 is such as -C n1 F m1 H (2*n1+1-m1) (R1 is a fluorinated alkyl group) or -C n1 O x1 F m1 H (2*n1+1-m1) (R1 is a fluoroalkoxyalkyl group), wherein n1 represents the number of carbon atoms in the R1 group, and is an integer of 1-10; m1 represents the number of fluorine atoms substituted in the R1 group, and is an integer of 1-21; x1 represents the number of alkoxy groups of R1 being a fluoroalkoxyalkyl group, for example, it can be 1, 2 or 3.

[0052] From the perspective of further improving the cycle performance, power output and safety of lithium batteries, n1 is preferably 3-8, more preferably 3-7, further preferably 3-6, and particularly preferably 3-5. From the perspective of further improving the cycle performance, power output and safety of lithium batteries, m1 is preferably 3 to (2*n1+1), more preferably 5 to (2*n1+1), and further preferably 7 to (2*n1+1).

[0053] In addition, in R1 of the present invention, n1 may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10; m1 may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or 21.

[0054] In some specific embodiments, R1 can be, for example, perfluoromethyl, perfluoroethyl, perfluoropropyl, perfluoro-n-butyl, perfluoroisobutyl, perfluoropentyl, perfluorohexyl, perfluoroheptyl, perfluorononyl, etc. In some specific embodiments, R1 can be, for example, CH3-O-CF2CF2-O-CF2-, CH3-O-CF2CF2-, CH3-O-CF(C3H7)-CF2-, etc.

[0055] In the present invention, R2 is such as -C n2 H (2*n2+1) or -C n2 F m2 H (2*n2+1-m2) (R2 is alkyl or fluoroalkyl), or -C n2 O x2 H (2*n2+1) or -C n2 O x2 F m2 H (2*n2+1-m2) (R2 is alkoxyalkyl or fluoroalkoxyalkyl), wherein n2 represents the number of carbon atoms in the R2 group, and is an integer of 1-5; m2 represents the number of fluorine atoms substituted in the R2 group, and is an integer of 1-11; x2 represents the number of alkoxy substitutions of R1 which is a fluoroalkoxyalkyl, for example, it can be 1, 2 or 3.

[0056] From the perspective of further improving the cycle performance, power output and safety of the lithium battery, n2 is preferably an integer of 1-3, more preferably 1-2, and further preferably 1. From the perspective of further improving the cycle performance, power output and safety of the lithium battery, m2 is preferably greater than 1, greater than 2, greater than 3; preferably less than 2*n2-2, less than 2*n2-1, less than 2*n2, less than 2*n2+1, etc.

[0057] Furthermore, in R2 of the present invention, n2 may be, for example, 1, 2, 3, 4 or 5; and m2 may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11.

[0058] In some specific embodiments, R2 can be, for example, methyl, ethyl, propyl, n-butyl, isobutyl, perfluoromethyl, perfluoroethyl, perfluoropropyl, etc.

[0059] Examples of fluorinated ether compounds include perfluoropropyl methyl ether (C3ME, CF3CF2CF2OCH3), perfluoroisobutyl methyl ether (C4ME, (CF3)2CFCF2OCH3), perfluoro-n-butyl methyl ether (CF3CF2CF2CF2OCH3), perfluoropentyl methyl ether (C5ME, for example (CF3)2CFCF(OCH3)CF3), perfluorohexyl methyl ether (C6ME, for example (CF3)2CFCF(OCH3)CF2CF3), perfluoro-3-oxobutyl Methyl ether (X1ME, CF3OCF2CF2OCH3), perfluoro-3,5-dioxahexyl methyl ether (X2ME, CF3OCF2OCF2CF2OCH3), perfluoro-2-oxahexyl methyl ether (6XME, CF3OCF2CF(OCH3)CF(CF3)2), ethyl perfluorobutyl ether (C4FE, such as (CF3)2CFCF2OCH2CH3), perfluorodimethyl ether (CF3OCF3), perfluoromethyl perfluoroethyl ether (CF3CF2OCF3), perfluoromethyl Perfluoropropyl ether (e.g. CF3CF2CF2OCF3), perfluoromethyl perfluorobutyl ether (e.g. (CF3)2CFCF2OCF3, CF3CF2CF2CF2OCF3), perfluoroethyl methyl ether (CF3CF2OCH3), perfluoroethyl ethyl ether (CF3CF2OCH2CH3), perfluoroethyl propyl ether (e.g. CF3CF2OCH2CH2CH3), perfluoroethyl butyl ether (e.g. CF3CF2OCH2CH2CH2CH3, CF3CF2OCH2C H(CH3)2), perfluoropropyl butyl ether (e.g., CF3CF2CF2OCH2CH2CH2CH3, CF3CF2CF2OCH2CH(CH3)2), perfluorobutyl butyl ether (e.g., (CF3)2CFCF2OCH2CH(CH3)2, (CF3)2CFCF2OCH2CH2CH2CH3, CF3CF2CF2CF2OCH2CH(CH3)2, CF3CF2CF2CF2OCH2CH2CH2CH3).

[0060] According to some preferred embodiments of the present invention, the fluorine-containing ether compound is one or more of perfluoropropyl methyl ether, perfluoroisobutyl methyl ether and perfluoropentyl methyl ether.

[0061] In addition, the fluorinated ether compound may account for more than 1% of the total volume of the composite electrolyte. For example, the fluorinated ether compound may account for 1-80% of the total volume of the composite electrolyte.

[0062] According to the present invention, the first lithium salt may use various lithium salts commonly used in lithium battery electrolytes, for example, one or more of lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate (LiAsF6), lithium fluorosulfonate (LiFSO3), lithium hexafluoroaluminate (LiAlF6), lithium tetrafluoroborate (LiBF4), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiCF3SO3), lithium tetrafluoroborate (LiBF4) and lithium bis(fluorosulfonyl)imide (LiFSI). The first lithium salt is preferably LiTFSI, LiFSI, etc.

[0063] From the perspective of improving the cycle performance, power output and safety of lithium metal batteries, preferably, in the composite electrolyte, the content of the first lithium salt is 0.5-4.5M, preferably 0.7-3M, and more preferably 0.8-1.5M.

[0064] According to the present invention, the composite electrolyte may further optionally contain a second lithium salt, which may be selected from one or more of lithium nitrate (LiNO3), lithium difluorooxalatoborate (LiDFOB), lithium bis(oxalateborate) (LiBOB) and lithium fluoride (LiF).

[0065] From the perspective of improving the cycle performance, power output and safety of lithium metal batteries, preferably, in the composite electrolyte, the content of the second lithium salt is 0.5-5 wt%, more preferably 0.7-3 wt%, and further preferably 0.8-2wt%.

[0066] According to the present invention, the composite electrolyte may further optionally contain an additive, and the additive may be selected from one or more of fluoroethylene carbonate (FEC), vinylene carbonate (VC), succinonitrile (SN), methylene disulfonate (MMDS), 1,3-propane sultone (PS), propenyl-1,3-sultone (PST), and diethylene sulfate (DTD).

[0067] From the perspective of improving the cycle performance, power output and safety of lithium metal batteries, preferably, in the composite electrolyte, the content of the additive is 0.5-5 wt%, more preferably 0.7-3 wt%, and further preferably 0.8-2 wt%.

[0068] In order to further improve the cycle performance, power output and safety of lithium metal batteries, preferably, the volume ratio of DME to DOL in the composite solvent is 1:0.5-1.5, preferably 1:0.8-1.2, and more preferably 1:0.9-1.1. And, preferably, the molar ratio of the total of DME and DOL in the composite solvent to the fluorinated ether compound is 1:1-10, preferably 1:1-5, more preferably 1:1-3, and further preferably 1:1.8-2.8.

[0069] According to some preferred embodiments of the present invention, the fluorinated ether compound is perfluoropropyl methyl ether and / or perfluoroisobutyl methyl ether, more preferably perfluoroisobutyl methyl ether or a mixture of perfluoropropyl methyl ether and perfluoroisobutyl methyl ether. According to some preferred embodiments of the present invention, the fluorinated ether compound is a mixture of perfluoropropyl methyl ether and perfluoroisobutyl methyl ether, and the volume ratio of perfluoroisobutyl methyl ether to perfluoropropyl methyl ether is 1:0.1-10, preferably 1:0.5-5, more preferably 1:1-2.

[0070] According to some preferred embodiments of the present invention, the composite solvent is composed of ethylene glycol dimethyl ether (DME), 1,3-dioxolane (DOL) and a fluorine-containing ether compound.

[0071] As a preparation method of the composite electrolyte of the present invention, for example, DME or DOL can be used alone as needed, or DME and DOL can be mixed in an appropriate ratio and further mixed with a fluorine-containing ether compound to form a composite solvent; lithium nitrate and the first lithium salt are dissolved in the composite solvent at corresponding concentrations to obtain the composite electrolyte of the present invention. During the mixing process, heating (for example, low-temperature heating at 40-50°C) can be performed as needed to promote the dissolution of related components.

[0072] The second aspect of the present invention provides the use of the composite electrolyte according to the first aspect of the present invention in a lithium battery.

[0073] The third aspect of the present invention provides a lithium battery, which includes a negative electrode, an electrolyte, a separator, and a positive electrode; wherein the electrolyte is the composite electrolyte of the first aspect of the present invention.

[0074] In the second and third aspects of the present invention as described above, there is no particular limitation on the type of lithium battery, for example, it can be a lithium metal battery, a lithium ion battery, a lithium sulfur battery or a lithium air battery, wherein a lithium metal battery is preferred. When the composite electrolyte of the present invention is used in a lithium metal battery, it can particularly improve various aspects of the performance of the lithium metal battery.

[0075] In addition, the lithium battery is preferably a lithium battery to which lithium replenishment technology is applied.

[0076] In the lithium battery of the present invention, the negative electrode may include a negative electrode active material capable of releasing and accepting lithium ions. For example, the active material of the negative electrode may be lithium metal, lithium alloy, or carbon material doped or undoped with lithium ions.

[0077] In some specific embodiments, the negative electrode active material is lithium metal. Preferably, the thickness of the lithium metal sheet is 5-50 μm, preferably 5-20 μm.

[0078] In some embodiments, the negative electrode active material is a carbon material doped or undoped with lithium ions. Such a carbon material can be graphite or amorphous carbon, and any carbonaceous material such as activated carbon, carbon fiber, carbon black, medium carbon microbeads, etc. can be used.

[0079] In the lithium battery of the present invention, the positive electrode may include a positive electrode active material capable of extracting and accepting lithium ions.

[0080] In some specific embodiments, the positive electrode active material can be a composite oxide or sulfide of lithium and a transition metal (such as MnO2, V2O 5、 MoS2, TiS2, etc.). Among them, the composite oxides used as positive electrode active materials include LiCoO2, LiMnO2, LiMn2O4, LiNiO2, etc.

[0081] In some specific embodiments, the positive electrode active material is a nickel-cobalt-manganese ternary positive electrode material (such as NCM111, NCM523, NCM622 and NCM811, etc.), a nickel-cobalt-aluminum ternary positive electrode material NCA (common ratio is 8:1.5:0.5), a lithium iron phosphate positive electrode material, a lithium iron manganese phosphate positive electrode material, etc. Preferably, the positive electrode active material of the present invention is a high-nickel ternary positive electrode material or a lithium iron phosphate positive electrode material.

[0082] In the lithium battery of the present invention, the separator is not particularly limited, for example, various separators commonly used in lithium batteries of the present invention can be used. From the perspective of obtaining higher battery performance by cooperating with the composite electrolyte, the separator of the present invention can be a PE film or a PP film.

[0083] In the present invention, there is no particular limitation on the shape and style of the lithium battery. The lithium battery of the present invention can be cylindrical, square, coin-shaped, card-shaped, large-sized or similar shapes. Within the scope of the present invention, the specific shape can be selected as needed.

[0084] Since the nonaqueous electrolyte battery of the present invention contains the above-mentioned nonaqueous electrolyte as an electrolyte, it can be used as a nonaqueous rechargeable battery that can generate a high voltage and whose battery performance does not decrease even after repeated charge and discharge.

[0085] Example The experimental methods in the following examples are conventional methods unless otherwise specified. The reagents used in the following examples are commercially available unless otherwise specified.

[0086] In the following examples and comparative examples, the abbreviations of the relevant compounds are as follows.

[0087] ·LiTFSI: Lithium bis(trifluoromethanesulfonyl)imide ·DME: Ethylene glycol dimethyl ether ·DOL:1,3-Dioxolane In each formulation of the following examples and comparative examples, the structural formulas of the relevant compounds are respectively shown in Table 1 below.

[0088] Table 1

[0089] Comparative Example 1 This example is used to illustrate the preparation method of a comparative composite electrolyte. The composition of the comparative composite electrolyte is as follows, also referred to as Formula A herein.

[0090] Solvent: DME / DOL composite solvent with a volume ratio of 1:1 Lithium salt: 1.2M LiTFSI, 1wt% LiNO3 (both final concentrations, the same below) Example 1 This example is used to illustrate the preparation method of the composite electrolyte of the present invention. The composition of the composite electrolyte is as follows, also referred to as formulation B herein.

[0091] Solvent: a composite solvent consisting of a DME / DOL mixed liquid (the volume ratio of DME / DOL in the mixed liquid is 1:1) and perfluoroisobutyl methyl ether, wherein the molar ratio of the DME / DOL mixed liquid to the perfluoroisobutyl methyl ether is 1:2.

[0092] Lithium salt: 1.2M LiTFSI, 1wt% LiNO3.

[0093] Example 2 This example is used to illustrate the preparation method of the composite electrolyte of the present invention. The composition of the composite electrolyte is as follows, also referred to as Formula C herein.

[0094] Solvent: a composite solvent consisting of a DME / DOL mixed liquid (the volume ratio of DME / DOL in the mixed liquid is 1:1) and a perfluoroisobutyl methyl ether / perfluoropropyl methyl ether mixed liquid (the volume ratio of perfluoroisobutyl methyl ether / perfluoropropyl methyl ether in the mixed liquid is 1:1), wherein the molar ratio of the DME / DOL mixed liquid to the perfluoroisobutyl methyl ether / perfluoropropyl methyl ether mixed liquid is 1:2.

[0095] Lithium salt: 1.2M LiTFSI, 1wt% LiNO3.

[0096] Example 3 This example is used to illustrate the preparation method of the composite electrolyte of the present invention. The composition of the composite electrolyte is as follows, also referred to as Formula D herein.

[0097] Solvent: a composite solvent consisting of a DME / DOL mixed liquid (the volume ratio of DME / DOL in the mixed liquid is 1:1) and a perfluoroisobutyl methyl ether / perfluoropropyl methyl ether mixed liquid (the volume ratio of perfluoroisobutyl methyl ether / perfluoropropyl methyl ether in the mixed liquid is 1:2), wherein the molar ratio of the DME / DOL mixed liquid to the perfluoroisobutyl methyl ether / perfluoropropyl methyl ether mixed liquid is 1:2.

[0098] Lithium salt: 1.2M LiTFSI, 1wt% LiNO3.

[0099] Example 4 This example is used to illustrate the preparation method of the composite electrolyte of the present invention. The composition of the composite electrolyte is as follows, also referred to as Formula E herein.

[0100] Solvent: a composite solvent composed of a DME / DOL mixed liquid (the volume ratio of DME / DOL in the mixed liquid is 1:1) and perfluoropentyl methyl ether, wherein the molar ratio of the DME / DOL mixed liquid to the perfluoropentyl methyl ether is 1:2.

[0101] Lithium salt: 1.2M LiTFSI, 1wt% LiNO3.

[0102] Example 5 This example is used to illustrate the preparation method of the composite electrolyte of the present invention. The composition of the composite electrolyte is as follows, also referred to as Formula F herein.

[0103] Solvent: a composite solvent composed of a DME / DOL mixed liquid (the volume ratio of DME / DOL in the mixed liquid is 1:1) and perfluoropropyl methyl ether, wherein the molar ratio of the DME / DOL mixed liquid to the perfluoropropyl methyl ether is 1:2.

[0104] Lithium salt: 1.2M LiTFSI, 1wt% LiNO3.

[0105] Example 6 This example is used to illustrate the preparation method of the composite electrolyte of the present invention. The composition of the composite electrolyte is as follows, also referred to as Formula G herein.

[0106] Solvent: a composite solvent composed of a DME / DOL mixed liquid (the volume ratio of DME / DOL in the mixed liquid is 1:1) and perfluoroisobutyl methyl ether, wherein the molar ratio of the DME / DOL mixed liquid to the perfluoroisobutyl methyl ether is 1:1.

[0107] Lithium salt: 1.2M LiTFSI, 1wt% LiNO3.

[0108] Example 7 This example is used to illustrate the preparation method of the composite electrolyte of the present invention. The composition of the composite electrolyte is as follows, also referred to as Formula H herein.

[0109] Solvent: a composite solvent consisting of a DME / DOL mixed liquid (the volume ratio of DME / DOL in the mixed liquid is 1:1) and perfluoroisobutyl methyl ether, wherein the molar ratio of the DME / DOL mixed liquid to the perfluoroisobutyl methyl ether is 1:3.

[0110] Lithium salt: 1.2M LiTFSI, 1wt% LiNO3.

[0111] Example 8 This example is used to illustrate the preparation method of the composite electrolyte of the present invention. The composition of the composite electrolyte is as follows, also referred to as Formula I herein.

[0112] Solvent: a composite solvent consisting of a DME / DOL mixed liquid (the volume ratio of DME / DOL in the mixed liquid is 2:1) and perfluoroisobutyl methyl ether, wherein the molar ratio of the DME / DOL mixed liquid to the perfluoroisobutyl methyl ether is 1:2.

[0113] Lithium salt: 1.2M LiTFSI, 1wt% LiNO3.

[0114] Example 9 This example is used to illustrate the preparation method of the composite electrolyte of the present invention. The composition of the composite electrolyte is as follows, also referred to as Formula J herein.

[0115] Solvent: a composite solvent composed of a DME / DOL mixed liquid (the volume ratio of DME / DOL in the mixed liquid is 1:2) and perfluoroisobutyl methyl ether, wherein the molar ratio of the DME / DOL mixed liquid to the perfluoroisobutyl methyl ether is 1:2.

[0116] Lithium salt: 1.2M LiTFSI, 1wt% LiNO3.

[0117] Example 10 This example is used to illustrate the preparation method of the composite electrolyte of the present invention. The composition of the composite electrolyte is as follows, also referred to as Formula K herein.

[0118] Solvent: a composite solvent consisting of a DME / DOL mixed liquid (the volume ratio of DME / DOL in the mixed liquid is 1:1) and perfluoro-3-oxobutyl methyl ether, wherein the molar ratio of the DME / DOL mixed liquid to the perfluoro-3-oxobutyl methyl ether is 1:2.

[0119] Lithium salt: 1.2M LiTFSI, 1wt% LiNO3.

[0120] Embodiment 11 This example is used to illustrate the preparation method of the composite electrolyte of the present invention. The composition of the composite electrolyte is as follows, also referred to as Formula L herein.

[0121] Solvent: a composite solvent consisting of a DME / DOL mixed liquid (the volume ratio of DME / DOL in the mixed liquid is 1:1) and ethyl perfluorobutyl ether, wherein the molar ratio of the DME / DOL mixed liquid to the ethyl perfluorobutyl ether is 1:2.

[0122] Lithium salt: 1.2M LiTFSI, 1wt% LiNO3.

[0123] Example 12 This example is used to illustrate the preparation method of the composite electrolyte of the present invention. The composition of the composite electrolyte is as follows, also referred to as Formula M herein.

[0124] Solvent: a composite solvent consisting of a DME / DOL mixed liquid (the volume ratio of DME / DOL in the mixed liquid is 1:1) and perfluoroethyl propyl ether, wherein the molar ratio of the DME / DOL mixed liquid to the perfluoroethyl propyl ether is 1:2.

[0125] Lithium salt: 1.2M LiTFSI, 1wt% LiNO3.

[0126] Test Example 1 The composite electrolytes of Comparative Example 1 and Examples 1-4 were used to assemble batteries, and the positive electrode used NCM811 ternary material with a loading capacity of 3.2 mAh / cm 2 ; The negative electrode uses 20 μm lithium metal; the separator uses PE film.

[0127] The battery assembled above was used to perform AC impedance test using an electrochemical workstation, with an amplitude voltage of 10mV and a test frequency range of 0.1Hz-100kHz. The measured data is the impedance value. The battery cycle test was performed using a Xinwei battery cycle tester, with the test conditions being 0 / 5C charging and 1C discharging. See Table 2 for specific results.

[0128] Table 2

[0129] Figure 1The impedance data of the battery assembled by the composite electrolyte of formula A and formula B are shown. The battery was tested after 24 hours of storage, using the test standard of 0.5C charging and 1C discharging. The impedance of formula A is significantly higher than that of formula B, indicating that formula B is more stable to lithium metal than formula A, and the SEI film formed is thinner or has higher ion conductivity.

[0130] Figure 2 The data shows the cycle performance of batteries assembled from the composite electrolytes of Formula A and Formula B at room temperature. The batteries were tested after 24 hours of storage, using the test standard of 0.33C charging and 1C discharging. By comparison, it can be seen that the stability of Formula B is much better than that of Formula A because Formula B can form a stable SEI film. In addition, Formula B can improve the cycle performance of the battery by at least 10-15 times, greatly improving and commercializing lithium metal batteries.

[0131] Figure 3 The data of the rate performance of the battery assembled by the composite electrolyte of formula A and formula B at room temperature are shown. The battery is tested after being stored for 24 hours, using the test standard of 0.33C charging and different discharge rates (0.2C, 0.5C, 1C, 2C and 0.5C). From the obtained rate performance data, the stability of formula B is much better than that of formula A, because formula B can form a stable SEI film. In addition, formula B can greatly improve the rate performance of lithium metal batteries compared with formula A, indicating that the formed SEI film is stable, is not destroyed or can be repaired in time during the high rate discharge process, and lithium ions can be deposited more evenly.

[0132] Figure 4 The impedance data of batteries assembled from composite electrolytes of Formula A, Formula C and Formula D are shown. The batteries were tested after being stored for 24 hours, using the test standard of 0.5C charging and 1C discharging. The impedance of Formula A is significantly higher than that of Formula C and Formula D, indicating that the fluorinated ether additives of Formula C and Formula D can significantly reduce the impedance of the common ether DME / DOL of the battery, which is more stable to lithium metal than Formula A, and the SEI film formed is thinner or has better ion conductivity. The impedance of Formula D is slightly lower than that of Formula C, and the viscosity of Formula D is greater than that of Formula C. This shows that in lithium metal batteries, electrolytes with slightly higher viscosity have better stability to lithium metal and more uniform SEI film formation.

[0133] Figure 5The impedance data of batteries assembled from composite electrolytes of formula A and formula E are shown. The batteries were tested after 24 hours of storage, using a 0.5C charge and 1C discharge test standard. The impedance of formula A is significantly higher than that of formula E, indicating that formula E is still significantly better than the ordinary ether formula DME / DOL in lithium metal batteries. Compared with formula A, it is more stable to lithium metal, and the SEI film formed is thinner or has better ion conductivity. Compared with formulas B, C and D, the impedance of formula E has increased, indicating that the impedance of the formed SEI film is not as low as that of perfluoroisobutyl methyl ether and perfluoropropyl methyl ether.

[0134] From Table 1 and Figure 1-5 It can be seen from the results that the composite electrolyte of the present invention can significantly increase the number of cycles of lithium metal batteries and reduce the impedance of the battery. Specifically, by comparing Examples 1-5 and 10-12, it can be seen that when perfluoroisobutyl methyl ether, perfluoropropyl methyl ether, ethyl perfluorobutyl ether and perfluoroethyl propyl ether are used as fluorinated ether compounds, the number of cycles of lithium metal batteries can be further increased and the impedance of the battery can be reduced. By comparing Examples 1 and 6-9, it can be seen that when the molar ratio of the DME / DOL mixed solution to the fluorinated ether compound is 1:1.8-2.8, and / or the volume ratio of DME to DOL is 1:0.6-1.6, the number of cycles of lithium metal batteries can be further increased and the impedance of the battery can be reduced.

[0135] The exemplary embodiments of the present invention are described above by way of examples, but the present invention is not limited thereto. It should be understood by those skilled in the art that the above examples are for illustrative purposes only, and the specific embodiments and examples of the present invention should not be considered to limit the scope of the present invention. The embodiments can be changed and altered within the scope of the gist of the present invention, and such changes and alterations should belong to the protection scope of the present invention.

Claims

1. A composite electrolyte, characterized in that: The composite electrolyte comprises a first lithium salt and a composite solvent; The composite solvent comprises ethylene glycol dimethyl ether (DME) and / or 1,3-dioxolane (DOL), and a fluorine-containing ether compound, and the molar ratio of the total of DME and DOL to the fluorine-containing ether compound is 1:0.2-10; The fluorine-containing ether compound is represented by the formula R1-O-R2; In the formula, R1 is a C1-C10 fluorinated alkyl group or a fluorinated alkoxyalkyl group, and R2 is an arbitrarily fluorinated C1-C5 alkyl group or an alkoxyalkyl group.

2. The composite electrolyte according to claim 1, wherein R1 as-C n1 F m1 H (2*n1+1-m1) or -C n1 O x1 F m1 H (2*n1+1-m1) As shown in the formula, n1 represents the number of carbon atoms in the R1 group, and is an integer of 1-10, preferably 3-7, and more preferably 3-5; m1 represents the number of fluorine atoms substituted in the R1 group, and is an integer of 3-21, preferably 7-15, and more preferably 7-11; x1 represents the number of alkoxy substitutions of R1 as a fluoroalkoxyalkyl group, and is an integer of 1-3, preferably 1 or 2.

3. The composite electrolyte according to claim 1, wherein R2 as -C n2 H (2*n2+1) or -C n2 F m2 H (2*n2+1-m2) , or -C n2 O x2 H (2*n2+1) or -C n2 O x2 F m2 H (2*n2+1-m2) As shown in the formula, n2 represents the number of carbon atoms in the R2 group, and is an integer of 1-5, preferably 1-3; m2 represents the number of fluorine atoms substituted in the R2 group, and is an integer of 0-11, preferably 0-7; x2 represents the number of alkoxy substitutions of R1 as a fluoroalkoxyalkyl group, and is an integer of 1-3, preferably 1 or 2.

4. The composite electrolyte according to claim 1, wherein The fluorinated ether compound is one or more of perfluoropropyl methyl ether, perfluoroisobutyl methyl ether, perfluoro-n-butyl methyl ether, perfluoropentyl methyl ether, perfluorohexyl methyl ether, perfluoro-3-oxabutyl methyl ether, perfluoro-3,5-dioxahexyl methyl ether, perfluoro-2-oxahexyl methyl ether, ethyl perfluorobutyl ether, perfluorodimethyl ether, perfluoromethyl perfluoroethyl ether, perfluoromethyl perfluoropropyl ether, perfluoromethyl perfluorobutyl ether, perfluoroethyl methyl ether, perfluoroethyl ethyl ether, perfluoroethyl propyl ether, perfluoroethyl butyl ether, perfluoropropyl butyl ether and perfluorobutyl butyl ether.

5. The composite electrolyte according to claim 1, wherein The fluorine-containing ether compound is one or more of perfluoropropyl methyl ether, perfluoroisobutyl methyl ether, ethyl perfluorobutyl ether and perfluoroethylpropyl ether.

6. The composite electrolyte according to claim 5, wherein: The fluorine-containing ether compound is perfluoropropyl methyl ether and / or perfluoroisobutyl methyl ether.

7. The composite electrolyte according to any one of claims 1 to 6, wherein: The first lithium salt is selected from one or more of lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate (LiAsF6), lithium fluorosulfonate (LiFSO3), lithium hexafluoroaluminate (LiAlF6), lithium tetrafluoroborate (LiBF4), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiCF3SO3), lithium tetrafluoroborate (LiBF4) and lithium bis(fluorosulfonyl)imide (LiFSI).

8. The composite electrolyte according to claim 7, wherein: The composite electrolyte further comprises a second lithium salt and / or an additive; Preferably, the second lithium salt is selected from one or more of lithium nitrate (LiNO3), lithium difluorooxalatoborate (LiDFOB), lithium bis(oxalateborate) (LiBOB), and lithium fluoride (LiF); Preferably, the additive is selected from one or more of fluoroethylene carbonate (FEC), vinylene carbonate (VC), succinonitrile (SN), methylene methanedisulfonate (MMDS), 1,3-propane sultone (PS), propenyl-1,3-sultone (PST), and dithiodiphenylamine (DTD).

9. The composite electrolyte according to claim 8, wherein: In the composite electrolyte, the content of the first lithium salt is 0.5-4.5M, preferably 0.7-3M; and / or The content of the second lithium salt is 0.5-5 wt %, preferably 0.7-3 wt %.

10. The composite electrolyte according to any one of claims 1 to 6, wherein: The molar ratio of the total of DME and DOL to the fluorine-containing ether compound in the composite solvent is 1:1-10, preferably 1:1-5, more preferably 1:1.8-2.8; Preferably, the volume ratio of DME to DOL in the composite solvent is 1:0.1-10, preferably 1:0.3-5.3, and more preferably 1:0.6-1.

6.

11. The composite electrolyte according to any one of claims 1 to 6, wherein: The composite solvent consists of ethylene glycol dimethyl ether (DME), 1,3-dioxolane (DOL) and fluorine-containing ether compounds.

12. Use of the composite electrolyte according to any one of claims 1 to 11 in a lithium battery.

13. The use according to claim 12, wherein: The lithium battery is a lithium metal battery, a lithium ion battery, a lithium sulfur battery or a lithium air battery.

14. A lithium battery, characterized in that: The lithium battery comprises a negative electrode, an electrolyte, a separator, and a positive electrode; wherein the electrolyte is the composite electrolyte according to any one of claims 1 to 11.

15. The lithium battery according to claim 14, wherein: The lithium battery is a lithium metal battery, a lithium ion battery, a lithium sulfur battery or a lithium air battery.

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