Electrolyte, secondary battery, battery module, battery pack, and power consumption device

Abstract

The present application provides an electrolyte solution, comprising a first solvent as shown in formula I and a second solvent selected from one or more of formulas II and III, wherein R1 is selected from a C1-C6 fluoro chain alkyl group, R2 is selected from a hydrogen atom, a C1-C6 chain alkyl group or a C1-C6 fluoro chain alkyl group, n is 1 or 2, and R3 to R 10 are each independently selected from a hydrogen atom, a fluorine atom, a C1-C6 alkyl chain or a C1-C6 fluoro alkyl chain. The electrolyte of the present application can improve the cycling stability and safety of the battery. The present application further relates to a secondary battery, a battery module, a battery pack and a power consuming device comprising the electrolyte. JPEG2025501295000019.jpg65170

Description

[Technical Field]

[0001] This application relates to the field of lithium battery technology, and in particular to electrolytes, secondary batteries, battery modules, battery packs, and power consuming devices. [Background technology]

[0002] Secondary batteries are widely used in many fields, including consumer electronics, electric vehicles, and energy storage. Improvements in the energy density of conventional lithium-ion secondary batteries are approaching their theoretical limits. To meet the demand for higher energy density in future applications, such as long-range electric vehicles and electric aircraft, there is a need to develop secondary batteries with the potential for higher energy density, such as metallic lithium secondary batteries that combine metallic lithium anodes with high-voltage cathodes, such as ternary systems. However, metallic lithium anodes have high reactivity and tend to spontaneously react with the electrolyte, forming a solid electrolyte interfacial layer (SEI) that has poor mechanical strength and chemical stability and induces dendritic growth. This leads to poor cycling, safety risks, and reduced lifespan due to rapid lithium source consumption.

[0003] The design and optimization of electrolytes is crucial to improving the cycling capacity of lithium metal batteries. However, with conventional technologies, electrolytes can cause systematic "transient" overcharge problems in lithium metal negative electrode secondary batteries, leading to difficult-to-control battery management difficulties and safety risks. Summary of the Invention [Problem to be solved by the invention]

[0004] In view of the above problems, the present application aims to provide an electrolyte solution that can avoid overcharging, improve the cycling stability and safety of lithium ion secondary batteries, and extend their cycling life.

[0005] To achieve the above object, the present application provides an electrolyte, a secondary battery containing the electrolyte, a battery module, a battery pack, and a power consuming device. [Means for solving the problem]

[0006] A first aspect of the present application provides an electrolyte solution, a first solvent, represented by formula I: [ka] however, R1 is selected from C1-C6 fluoro alkyl chains; R2 is selected from a hydrogen atom, a C1-C6 alkyl chain group and a C1-C6 fluoro alkyl chain group; the first solvent, wherein n is 1 or 2; a second solvent selected from one or more compounds of formula II and formula III; [ka] however, R3~R 10 and the second solvent, wherein each of the groups is independently selected from a hydrogen atom, a fluorine atom, a C1-C6 alkyl chain, and a C1-C6 fluoroalkyl chain. The electrolyte of the present application can avoid the "transient" overcharge problem during long-term cycling of secondary batteries, improving cycling stability and safety. In addition, the electrolyte of the present application has high oxidation stability and can improve the cycling life of metal or alloy negative electrode secondary batteries.

[0007] In any embodiment, in the formula I, R1 is selected from C1-C3 fluoro chain alkyl groups, preferably fluoromethyl, and / or R2 is selected from hydrogen atoms, C1-C3 chain alkyl groups and C1-C3 fluoro chain alkyl groups, preferably selected from hydrogen atoms, methyl, fluoromethyl, ethyl and fluoroethyl.

[0008] In any embodiment, in the formula II, R3 to R8 are each independently selected from a hydrogen atom, a fluorine atom, and a C1-C6 fluoro chain alkyl group, preferably selected from a hydrogen atom, a fluorine atom, and a C1-C3 fluoro chain alkyl group, and / or in the formula III, R9 to R 10 are each independently selected from a hydrogen atom, a fluorine atom, a C1-C6 alkyl chain and a C1-C6 fluoro alkyl chain, preferably a hydrogen atom, a fluorine atom, a C1-C3 alkyl chain and a C1-C3 fluoro alkyl chain, more preferably R9 to R 10 are each independently selected from a hydrogen atom and a fluorine atom.

[0009] By further selecting the first and second solvents, the electrolyte has high oxidation stability, avoids overcharging, and improves cycle life.

[0010] In any embodiment, the weight ratio of the first solvent to the second solvent is 0.5 to 3, preferably 0.7 to 1.5, and more preferably 0.9 to 1.1. By keeping the weight ratio of the two solvents within this range, overcharging can be avoided, the electrolyte salt can be well dissolved in the electrolyte solution, and the electrolyte solution can have excellent antioxidant capacity and a long circulation life.

[0011] In any embodiment, the electrolyte solution further comprises an antioxidant, preferably selected from at least one of lithium nitrate and lithium perchlorate, which contributes to further improving the cycle life.

[0012] In some embodiments, the concentration of the antioxidant is 0.5 wt % to 3 wt %, preferably 0.7 wt % to 1.5 wt %, and more preferably 0.9 wt % to 1.1 wt %, based on the total weight of the electrolyte. The addition of an antioxidant can further improve the critical voltage value of oxidation stability and further extend the cycle life. At the same time, by keeping the antioxidant content within the above range, the above effects can be fully achieved while avoiding excessive influence on the normal transport of lithium ions, which would result in a decrease in cycle life.

[0013] In any embodiment, the electrolyte solution further contains a fluorine-containing electrolyte salt, and preferably the fluorine-containing electrolyte salt is selected from at least one of lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bistrifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium difluorobis(oxalate)phosphate, and lithium tetrafluorooxalate phosphate, and more preferably the fluorine-containing electrolyte salt is lithium bis(fluorosulfonyl)imide. The use of such electrolyte salts contributes to improving the stability of the negative electrode interface and improving circulation performance.

[0014] In any embodiment, the concentration of the fluorine-containing electrolyte salt is 0.5 M to 3 M, preferably 1 M. An electrolyte salt at this concentration contributes to further improvement of circulation performance.

[0015] A second aspect of the present application provides a secondary battery including the electrolyte solution according to the first aspect of the present application.

[0016] A third aspect of the present application provides a battery module including the secondary battery according to the second aspect of the present application.

[0017] A fourth aspect of the present application provides a battery pack including the battery module according to the third aspect of the present application.

[0018] A fifth aspect of the present application provides a power consumption device including at least one selected from the secondary battery according to the second aspect of the present application, the battery module according to the third aspect, or the battery pack according to the fourth aspect.

[0019] The electrolyte of the present invention can improve the cycling stability of lithium ion secondary batteries, extend the cycling life, prevent overcharging, and improve the safety performance of the batteries. [Brief explanation of the drawings]

[0020] [Figure 1]FIG. 1 is a cycle life diagram of a secondary battery containing a prior art electrolyte. [Figure 2] 1 shows the oxidation stability test results of the prior art electrolyte. [Figure 3] These are the results of a test on the oxidation stability of a normal ether-based electrolyte and a fluorine-based electrolyte. [Figure 4] FIG. 2 is a cycle life diagram of a secondary battery including an electrolyte according to an embodiment of the present application. [Figure 5] 1 is a cyclic voltage-capacity curve of the secondary battery of Comparative Example 1. [Figure 6] FIG. 10 is a cycle life graph including a secondary battery containing the electrolyte solution of Comparative Example 2. [Figure 7] FIG. 10 is a cycle life graph of a secondary battery containing the electrolyte solution of Comparative Example 3. [Figure 8] FIG. 10 is a cycle life graph of a secondary battery containing the electrolyte solution of Comparative Example 4. [Figure 9] FIG. 10 is a cycle life graph of a secondary battery containing the electrolyte solution of Comparative Example 5. [Figure 10] FIG. 10 is a cycle life graph of a secondary battery containing the electrolyte solution of Comparative Example 6. [Figure 11] 1 is a schematic diagram of a secondary battery according to an embodiment of the present application; [Figure 12] FIG. 12 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. [Figure 13] 1 is a schematic diagram of a battery module according to an embodiment of the present application; [Figure 14] 1 is a schematic diagram of a battery pack according to an embodiment of the present application. [Figure 15] FIG. 15 is an exploded view of the battery pack according to the embodiment of the present application shown in FIG. 14. [Figure 16] 1 is a schematic diagram of a power consuming device that uses a secondary battery as a power source according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, with appropriate reference to the drawings, embodiments specifically disclosing the electrolyte, secondary battery, battery module, battery pack, and electric device of the present application will be described in detail. However, unnecessary details may be omitted. For example, detailed descriptions of already known matters or redundant descriptions of actually identical structures may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0022] The "ranges" disclosed herein are defined in the form of lower and upper limits. A given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of that particular range. Such defined ranges may be inclusive or exclusive, and may be arbitrarily combined; i.e., any lower limit may be combined with any upper limit to form a single range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if minimum range values ​​1 and 2 and maximum range values ​​3, 4, and 5 are listed, the following ranges are also contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. Unless otherwise specified, the numerical range "ab" herein refers to a shorthand notation for any combination of real numbers from a to b, where both a and b are real numbers. For example, the numerical range "0-5" refers to all real numbers between "0-5" listed herein, and "0-5" is simply a shorthand notation for combinations of these numbers. Also, when a parameter refers to an integer ≧2, the parameter is an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0023] Unless otherwise specified, all embodiments and preferred embodiments in this application can be combined with each other to form new technical solutions.

[0024] Unless otherwise specified, all technical features and preferred technical features of the present application can be combined with each other to form new technical solutions.

[0025] Unless otherwise specified, all steps herein may be performed sequentially or randomly, preferably sequentially. For example, a "method includes steps (a) and (b)" indicates that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, a "method may include step (c)" above indicates that step (c) can be added to the method in any order, e.g., the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b).

[0026] Unless otherwise specified, the terms "comprise" and "include" used in this application may be open-ended or exclusive. For example, the terms "comprise" and "include" may further comprise or include other components not listed, or may comprise or include only the listed components.

[0027] Unless otherwise specified, in this application, the term "or" is inclusive. For example, the words "A or B" indicate "A, B, or both A and B." More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) but B is true (or exists), or both A and B are true (or exist).

[0028] Secondary batteries are widely used in many fields, such as home appliances, electric vehicles, and energy storage. The improvement in the energy density of conventional lithium-ion secondary batteries is approaching its theoretical limit. To meet the demand for higher energy density in future applications, such as long-range electric vehicles and electric aircraft, there is a need to develop secondary batteries with the potential for higher energy density, such as metal or alloy negative-electrode ion secondary batteries.

[0029] However, as is known, metal or alloy anodes have high reactivity and are difficult to form a good solid electrolyte interfacial layer (SEI), which leads to dendritic growth morphology, resulting in less than ideal cycling capability, safety risks, and reduced lifespan due to rapid consumption of active ions.

[0030] The design of the electrolyte is crucial to improve the cycling capacity of metal and alloy anode secondary batteries. Many ether-based electrolytes, especially locally high-concentration ether-based electrolytes, have been applied to metal anode secondary battery systems in recent years, with good results.

[0031] However, during further evaluation of conventional ether-based electrolytes, the inventors discovered that when conventional locally high-concentration electrolytes were used in metal-negative secondary batteries (e.g., metal-lithium transition metal oxide batteries), the secondary batteries experienced systematic overcharge problems during long cycling (i.e., cycling of 50 or more cycles). Unlike known battery overcharge phenomena, these overcharge problems are transient. In other words, these overcharge problems only occur for a short period of time (or within a certain number of cycling cycles) during cycling, after which the battery returns to a normal cycling state. For example, as shown in FIG. 1, secondary batteries containing conventional electrolytes (e.g., LiFSI-DME-TTE system) experience an overcharge phenomenon during long cycling, where the charge capacity exceeds the rated capacity within a certain number of cycling cycles (approximately 40-65 cycles as shown in FIG. 1), while the discharge capacity remains normal or slightly decreases. As cycling continues beyond this range, the overcharge phenomenon gradually weakens and disappears, eventually returning to a normal cycling state. Based on current research, the inventors believe that such "transient" overcharge events may not significantly shorten the cycling life or degrade performance of the cell, but may therefore have a certain degree of stealth and difficulty in detection.

[0032] However, this transient overcharge issue in metal anode secondary batteries deserves serious attention. While a "transient" overcharge of a single cell may seem negligible, battery modules contain many identical cells assembled in series. If such transient overcharge occurs during the cycling process of such a large number of cells, the voltage may exceed the safe range, resulting in heat generation, gas generation, and battery side reactions. As a result, this overcharge issue can lead to difficult battery management and safety risks that are difficult to control. Therefore, this "transient" overcharge issue, despite its hidden nature, must be addressed immediately. Prior to this application, the prior art had not recognized the existence of this unique overcharge phenomenon, nor had it recognized its potential hazards in battery safety management.

[0033] To solve the above problems, the present application provides an electrolyte that can avoid the above-mentioned "transient" overcharge problem, improve the safety of metal or alloy negative electrode secondary batteries, and improve their cycling performance.

[0034] electrolyte In one embodiment of the present application, an electrolyte solution is provided, a first solvent, represented by formula I: [ka] however, R1 is selected from C1-C6 fluoro alkyl chains; R2 is selected from a hydrogen atom, a C1-C6 alkyl chain group and a C1-C6 fluoro alkyl chain group; the first solvent, wherein n is 1 or 2; a second solvent selected from one or more compounds of formula II and formula III; [ka] however, R3~R 10 are each independently selected from a hydrogen atom, a fluorine atom, a C1-C6 alkyl chain group, and a C1-C6 fluoro alkyl chain group, and the second solvent.

[0035] The electrolyte of the present application can avoid the above-mentioned "transient" overcharge problem during long-term cycling of secondary batteries, particularly lithium-ion secondary batteries with metal or alloy negative electrodes, thereby improving the cycling stability and safety of the battery. The electrolyte of the present application also has high oxidation stability, which can improve the cycling life of metal or alloy negative electrode secondary batteries.

[0036] While not wishing to be limited by any theory, the inventors have discovered that the inherent antioxidant capacity of ether-based electrolytes in the prior art is not particularly poor. For example, in a scanning voltammetry (LSV) test of a Li-Al battery, the oxidation stability window of a dimethyl ether (DME)-1,1,2,2-difluoroethyl-2,2,3,3-difluoropropyl ether (TTE) electrolyte system can reach 5.3 V (see FIG. 2). However, when such electrolytes are applied to, for example, Li-NMC811 cells and subjected to long-term cycling, the aforementioned "transient" overcharge problem inevitably occurs (see, for example, Comparative Example 3 and FIG. 7 below). The electrolyte of the present application has good oxidation resistance and can effectively prevent the occurrence of this "transient" overcharge phenomenon.

[0037] In some embodiments, in Formula I, R1 is selected from a C1-C3 fluoro chain alkyl group, preferably fluoromethyl. In some embodiments, R1 is more preferably monofluoromethyl or difluoromethyl. In some embodiments, in Formula I, R2 is selected from a hydrogen atom, a C1-C3 fluoro chain alkyl group, and a C1-C3 fluoro chain alkyl group, preferably selected from a hydrogen atom, methyl, fluoromethyl, ethyl, and fluoroethyl. In some embodiments, R2 is more preferably selected from a hydrogen atom, methyl, monofluoromethyl, difluoromethyl, ethyl, monofluoroethyl, and difluoroethyl.

[0038] In some embodiments, the first solvent of Formula I is the following compound: [ka] [ka] [ka] [ka] Selected from.

[0039] In some embodiments, the first solvent of formula I is selected from at least one of formulas I-1 to I-16 and I-60 to I-71, and more preferably at least one of formulas I-2 and I-65.

[0040] In the present application, the first solvent is preferably an ether with a short carbon chain length (e.g., a C1-3 alkyl chain) and a moderate fluorine content (e.g., monofluoro or difluoro) rather than an ether with a long carbon chain length and / or a high fluorine content. The first solvent provides the electrolyte with a high boiling point and high oxidative stability, enhancing the oxidative stability of the positive electrode. The first solvent also has good solubility for the electrolyte salt (e.g., lithium bis(fluorosulfonyl)imide (LiFSI) can be dissolved in the first solvent to a concentration of 2M or more). At the same time, when the first solvent is used alone and the lithium bis(fluorosulfonyl)imide salt concentration is 1M, the oxidative stability of the electrolyte in a Li-Al half-cell LSV test reaches at least about 5.3V (see Figure 3).

[0041] The second solvent as shown in Formula II and Formula III does not dissolve or only slightly dissolves the electrolyte lithium salt, and can dissolve with the first solvent in any proportion without phase separation.

[0042] In some embodiments, in Formula II, R3 to R8 are each independently selected from a hydrogen atom, a fluorine atom, and a C1-C6 fluoro chain alkyl group. Preferably, R3 to R8 are each independently selected from a hydrogen atom, a fluorine atom, and a C1-C3 fluoro chain alkyl group. In some embodiments, in Formula II, R3 to R8 are each independently selected from a hydrogen atom, a fluorine atom, and a fluoromethyl.

[0043] In some embodiments, the solvent of Formula II is the following compound: [ka] Selected from.

[0044] In some embodiments, the second solvent of Formula II is selected from at least one of difluorobenzene, fluoromethylbenzene, preferably at least one of difluorobenzene and trifluoromethylbenzene, more preferably at least one of compounds of Formula II-7, II-8, II-9, and II-12.

[0045] In some embodiments, in Formula III, R to R 10 are each independently selected from a hydrogen atom, a fluorine atom, a C1-C6 alkyl chain group, and a C1-C6 fluoro alkyl chain group. 10 are each independently selected from a hydrogen atom, a fluorine atom, a C1-C3 alkyl chain group, and a C1-C3 fluoro alkyl chain group. 10 are each independently selected from a hydrogen atom or a fluorine atom.

[0046] In the fluoro chain alkyl groups described herein, one or more hydrogen atoms of the chain alkyl group are each independently replaced with a fluorine atom.

[0047] In some embodiments, the solvent of Formula III is the following compound: [ka] Selected from.

[0048] In some embodiments, the second solvent of formula III is selected from fluoromethoxybenzene, preferably selected from at least one of compounds of formula III-1, III-2, and III-3. In some embodiments, the second solvent of formula III is a compound of formula III-3.

[0049] In some embodiments, the second solvent is a compound of Formula III.

[0050] In this application, the combination of the first and second solvents can prevent overcharging. The second solvent has a benzene ring structure, and the large conjugated π bond helps prevent the solvent molecules from losing electrons during the electrochemical process, which also helps improve the antioxidant ability of the electrolyte. When the benzene ring is directly connected to an oxygen atom, the electron cloud of the oxygen atom is attracted and added to the conjugated bond of the benzene ring, further improving its antioxidant ability.

[0051] In some embodiments, the weight ratio of the first solvent to the second solvent is 0.5 to 3, preferably 0.7 to 1.5, and more preferably 0.9 to 1.1. In some embodiments, the weight ratio of the first solvent to the second solvent is 1. By keeping the weight ratio of the two solvents within this range, the occurrence of transient overcharging can be avoided, the electrolyte salt can be well dissolved in the electrolyte solution, and the electrolyte solution can have excellent antioxidant capacity and a long circulation life.

[0052] In some embodiments, the electrolyte solution further includes an antioxidant, preferably at least one of lithium nitrate and lithium perchlorate. In some embodiments, the antioxidant is lithium nitrate. The use of a combination of the first solvent, the second solvent, and the antioxidant can effectively prevent overcharging during long-term cycling of lithium metal negative electrode secondary batteries, particularly lithium metal negative electrode-ternary positive electrode secondary batteries. The addition of the antioxidant additive (especially in combination with the fluorine ether compound in the electrolyte) can change the local solvation structure at the interface between the positive electrode and the electrolyte, and its anion moiety (e.g., nitrate radicals and perchlorate radicals) is attracted to the electric double layer on the surface of the ternary positive electrode during charging and more closely binds with the active ions (e.g., lithium ions in the case of lithium-ion batteries), reducing the degree of involvement of the solvent molecules around the active ions in the electric double layer, thereby reducing the contact between the solvent molecules and the ternary positive electrode and reducing the transition metal-catalyzed oxidation of the solvent molecules, further protecting the positive electrode and extending the cycle life.

[0053] In some embodiments, the concentration of the antioxidant is 0.5 wt % to 3 wt %, preferably 0.7 wt % to 1.5 wt %, and more preferably 0.9 wt % to 1.1 wt %, based on the total weight of the electrolyte. The addition of an antioxidant can further improve the critical voltage value of oxidation stability and further extend the cycle life. At the same time, by keeping the antioxidant content within the above range, these effects can be fully achieved while avoiding excessive influence on the normal transport of lithium ions, which would result in a decrease in cycle life.

[0054] In some embodiments, the electrolyte solution of the present invention further comprises a fluorine-containing electrolyte salt. Preferably, the fluorine-containing electrolyte salt is selected from at least one of lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bistrifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium difluorobis(oxalate)phosphate, and lithium tetrafluorooxalate phosphate. In some embodiments, the fluorine-containing electrolyte salt is preferably lithium bis(fluorosulfonyl)imide. The fluorine-containing electrolyte salt has good solubility in the electrolyte solution of the present invention (especially in the first solvent). It can also decompose on the surface of a metal or alloy negative electrode (e.g., a lithium metal negative electrode) to form an inorganic fluorine-rich SEI component, improving the stability of the negative electrode interface and further improving the cycle life of metal or alloy negative electrode secondary batteries.

[0055] In some embodiments, the concentration of the fluorine-containing electrolyte salt is 0.5 M to 3 M, preferably 1 M. By adopting the above concentration, the cycle life of the secondary battery can be improved.

[0056] In some embodiments, the electrolyte solution preferably further contains an additive. For example, the additive may include a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive that can improve certain battery performance, such as an additive that improves the overcharge performance of the battery or an additive that improves the high-temperature or low-temperature performance of the battery.

[0057] Secondary battery, battery module, battery pack, and power consumption device

[0058] In another embodiment of the present application, a secondary battery containing the above-described electrolyte solution is provided.

[0059] In some embodiments, the secondary battery is a lithium ion secondary battery.

[0060] In some embodiments, the secondary battery is a metal or alloy anode secondary battery, hi some embodiments, the secondary battery is a metal lithium anode secondary battery, preferably a metal lithium anode-lithium transition metal oxide cathode secondary battery.

[0061] The secondary battery according to the present invention contains the electrolyte solution of the present invention, and therefore has more stable cycling, is free from overcharging, and can achieve a longer cycling life.

[0062] A typical secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During the charge and discharge process, active ions are absorbed and released back and forth between the positive and negative electrode sheets. The electrolyte serves to conduct ions between the positive and negative electrode sheets. The separator, located between the positive and negative electrode sheets, primarily serves to prevent short circuits between the positive and negative electrodes while allowing ions to pass through.

[0063] [Positive electrode sheet]

[0064] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer including a positive electrode active material including a lithium transition metal oxide and / or a lithium phosphate selected from an olivine structure. In some embodiments, the positive electrode active material is selected from a lithium transition metal oxide. In some embodiments, the lithium transition metal oxide is selected from lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, or a combination thereof.

[0065] Examples of lithium transition metal oxides include lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (can also be abbreviated as LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (can also be abbreviated as LiNi 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (can also be abbreviated as LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM 622 (can also be abbreviated as LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM 811 (can also be abbreviated as LiNi 0.96 Co 0.02 Mn 0.02 O2(Ni 96 ), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co0.15 Al 0.05 O2) and modified compounds, etc.

[0066] Examples of the lithium-containing phosphate having an olivine structure include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which can also be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0067] For example, the positive electrode current collector has two surfaces facing each other in the thickness direction thereof, and the positive electrode film layer is provided on either one or both of the two facing surfaces of the positive electrode current collector.

[0068] In some embodiments, a positive electrode film layer is provided on both sides of the positive electrode current collector.

[0069] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, aluminum foil may be used as the metal foil sheet. The composite current collector includes a polymer substrate layer and a metal layer formed on at least one surface of the polymer substrate layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0070] In some embodiments, the positive electrode active material may be a battery positive electrode active material known in the art. For example, the positive electrode active material may include at least one of olivine-structured lithium-containing phosphates, lithium transition metal oxides, and modified compounds thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination.

[0071] In some embodiments, the positive electrode membrane layer preferably further includes a binder, for example, at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0072] In some embodiments, the positive electrode film layer preferably further includes a conductive agent, for example, superconducting carbon, acetylene black, carbon black, cochin black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0073] In some embodiments, the positive electrode sheet can be manufactured as follows: the components for manufacturing the positive electrode sheet, such as the positive electrode active material, conductive agent, binder, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, which is then coated onto a positive electrode current collector, followed by processes such as drying and cold pressing, to obtain a positive electrode sheet.

[0074] [Negative electrode sheet]

[0075] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer being selected from a pure metal, an intermetallic alloy, or a metal-nonmetallic alloy negative electrode active material. In some embodiments, the metal is selected from lithium (Li), tin (Sn), zinc (Zn), aluminum (Al), magnesium (Mg), silver (Ag), gold (Au), gallium (Ga), indium (In), platinum (Pt), or a combination thereof. In some embodiments, the nonmetal is selected from boron (B), carbon (C), silicon (Si), or a combination thereof.

[0076] These negative electrode active materials may be used alone or in combination of two or more.

[0077] For example, the negative electrode current collector has two surfaces opposing each other in the thickness direction thereof, and the negative electrode film layer is provided on either one or both of the two opposing surfaces of the negative electrode current collector.

[0078] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, copper foil may be used as the metal foil sheet. The composite current collector may include a polymer substrate layer and a metal layer formed on at least one surface of the polymer substrate layer. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0079] In some embodiments, the negative electrode film layer preferably further includes a binder, which may be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0080] In some embodiments, the negative electrode film layer preferably further includes a conductive agent, which may be selected from the group consisting of superconducting carbon, acetylene black, carbon black, cochin black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0081] In some embodiments, the negative electrode membrane layer preferably further contains other auxiliary agents such as a thickener (e.g., carboxymethylcellulose sodium (CMC-Na)).

[0082] In some embodiments, the negative electrode sheet can be manufactured as follows: the above-mentioned components for manufacturing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, which is then coated onto a negative electrode current collector, and the negative electrode sheet can be obtained after processes such as drying and cold pressing.

[0083] [Separator]

[0084] In some embodiments, the secondary battery further includes a separator. The present application is not particularly limited to the type of separator, and any known porous separator with good chemical and mechanical stability can be selected. In some embodiments, the separator can be, but is not limited to, a polyethylene porous film, a polypropylene porous film, a polyimide porous film, or a porous film composite of multiple polymers.

[0085] The separator is not particularly limited and may be a single-layer thin film or a multi-layer composite thin film. When the separator is a multi-layer composite thin film, the materials of each layer are not particularly limited and may be the same or different.

[0086] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be manufactured into an electrode assembly by a winding process or a lamination process.

[0087] In some embodiments, the secondary battery may include a housing, which can be used to seal the electrode assembly and electrolyte.

[0088] In some embodiments, the exterior of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the exterior of the secondary battery may be a soft bag, such as a pouch soft bag. The soft bag may be made of plastic, such as polypropylene, polybutylene terephthalate, or polybutylene succinate.

[0089] The present application is not particularly limited to the shape of the secondary battery, and it may be cylindrical, rectangular, or any other shape.

[0090] In a further embodiment of the present application, there is provided a battery module including the above secondary battery.

[0091] In a further embodiment of the present application, there is provided a battery pack including the battery module as described above.

[0092] In a further embodiment of the present application, there is provided a power consumption device including at least one selected from the above-described secondary battery, battery module, and battery pack.

[0093] Hereinafter, the secondary battery, battery module, battery pack, and power consuming device of the present application will be described with reference to the drawings.

[0094] FIG. 11 shows an example of a secondary battery 5 having a prismatic structure.

[0095] In some embodiments, referring to FIG. 12 , the exterior may include a housing 51 and a cover plate 53. The housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates may surround the housing 51 to form a storage chamber. The housing 51 may have an opening communicating with the storage chamber, and the cover plate 53 may cover the opening to close the storage chamber. The positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly 52 by a winding process or a lamination process. The electrode assembly 52 is sealed in the storage chamber. An electrolyte is impregnated into the electrode assembly 52. ​​The secondary battery 5 may include one or more electrode assemblies 52, and this can be selected by those skilled in the art according to specific practical needs.

[0096] In some embodiments, the secondary batteries can be assembled into a battery module, and the number of secondary batteries included in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0097] FIG. 13 shows an example of a battery module 4. Referring to FIG. 13, in the battery module 4, a plurality of secondary batteries 5 are arranged in a sequential manner along the length of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fastened together with a fastener.

[0098] Preferably, the battery module 4 may further include an outer case having a storage space, and the plurality of secondary batteries 5 are stored in the storage space.

[0099] In some embodiments, the battery modules can be further assembled into a battery pack, and the battery pack can include one or more battery modules. The specific number can be selected by those skilled in the art according to the application and capacity of the battery modules.

[0100] 14 and 15 show an example of a battery pack 1. Referring to FIGS. 14 and 15, the battery pack 1 may include a battery box and a plurality of battery modules 4 provided in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 may be covered by the lower housing 3 to form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 may be distributed in any manner within the battery box.

[0101] The present application also provides a power consumption device, which includes at least one of the secondary battery, battery module, or battery pack provided by the present application. The secondary battery, battery module, or battery pack can be used as a power source for the electrical device and also as an energy storage unit for the electrical device. The power consumption device includes, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), trains, ships, satellites, energy storage systems, etc.

[0102] The power consumption device can be selected from a secondary battery, a battery module, or a battery pack depending on the needs of the use.

[0103] 16 shows an example of a power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density demands of the secondary battery of the power consuming device, a battery pack or a battery module can be used.

[0104] Other examples of the device may be a mobile phone, a tablet, a laptop, etc. Such devices are usually required to be thin and can use a secondary battery as a power source. [Example]

[0105] The following examples of the present application are described. The examples described below are illustrative and are used only to interpret the present application, and should not be understood as limiting the present application. If specific techniques or conditions are not specified in the examples, they should be carried out according to the techniques or conditions described in the literature in the field or according to the product specifications. If the manufacturer of the reagents or equipment used is not specified, they are conventional products that can be purchased commercially.

[0106] Example 1 1. Preparation 1.1 Preparation of electrolyte: Equal masses of the first solvent of formula I-2 and the second solvent of formula III-3 were mixed and stirred to obtain a colorless, transparent, and homogeneous mixed solvent. 0.935 g of lithium bis(fluorosulfonyl)imide salt was added to 5 ml of the mixed solvent and stirred thoroughly to form a colorless, transparent solution with a 1 M concentration, which was used as the desired electrolyte. 1.2 Preparation of positive electrode sheet: LiNi, the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2(NCM 811 ), acetylene black as a conductive agent, and PVDF as an adhesive were mixed in a mass ratio of 98:1:1, and N-methylpyrrolidone (NMP) as a solvent was added and stirred until the system was homogenous to obtain a positive electrode slurry (solid content 70 wt%). The positive electrode slurry was then diluted to approximately 25 mg / cm 2 The positive electrode current collector aluminum foil was coated evenly on both sides with a loading amount of 10 ... 2 is. 1.3 Preparation of negative electrode sheet: A 50 μm lithium foil is coated on one surface of a 12 μm copper foil by roll pressing, and then cut into a rectangular shape of 41 mm*51 mm to be used later as a negative electrode sheet. 1.4 Separators: A polyethylene porous film is selected and cut into a rectangular shape of 45mm*55mm for later use. 1.5 Secondary Battery Assembly: One cut positive electrode and two cut negative electrodes were matched, and the separator described above was used between them to isolate the positive and negative electrodes. The laminated dry cell was then wrapped in an aluminum film bag. 0.3 g of the electrolyte solution prepared above was then poured into the aluminum film bag, which was then vacuum hot-pressed and allowed to stand at room temperature for at least 6 hours before starting the cycling test described in 2.1 below. The rated capacity of the secondary battery prepared in this manner was 140 mAh.

[0107] 2. Exam 2.1 Secondary battery cycling test: The ambient temperature for cell cycling was set to 25°C, and the secondary battery obtained in 1.5 above was cycled at a rate of 0.5C (i.e., 70mA) using a Neware cycling tester. The charge and discharge cutoff voltages were set to 4.3V and 2.8V, respectively. The battery's life was considered to end when the discharge capacity decreased to 80% of the discharge capacity at the first cycle, and the number of cycling cycles at this point was the cycling life. At the same time, the cycle number and the corresponding cycling charge / discharge capacity and coulombic efficiency (CE) of the tested battery during the cycling process are shown in Figure 4. As can be seen from Figure 4, the cycling life of the battery is 171 cycles, and there was no overcharging phenomenon throughout the life cycle, where the charging capacity was significantly higher than the rated capacity. 2.2 Li-Al half-cell LSV test for oxidation stability of electrolyte The negative electrode prepared in 1.3 above was taken as 50 μm, and aluminum foil was used as the positive electrode. 2 The battery is cut into round pieces, a polyethylene porous film of the same size is used as a separator, 20 μl of the electrolyte prepared in 1 above is poured into it, and the button battery to be measured is assembled. Using a Solartron electrochemical station, scan voltammetry (LSV) tests are performed at a sweep rate of 5 mV / s in the voltage range from the open circuit voltage to 6 V, and the current response of the button cell is recorded. 2 When the voltage reaches the critical voltage value for the oxidation stability of the electrolyte. When measured by this method, the oxidation stability of the electrolyte solution obtained in Example 1 was 5.4V.

[0108] Examples 2-9 The electrolyte solution and secondary battery were prepared with reference to Example 1, and the corresponding tests were carried out, with the difference being that the first and second solvents in these examples were different.

[0109] Examples 10-17 The electrolyte solution and secondary battery were prepared with reference to Example 1, and the corresponding tests were carried out, with the difference being that the mass ratio values ​​of the first and second solvents in these examples were different.

[0110] Comparative Example 1 A typical ether-based electrolyte solution in the prior art is prepared and tested with reference to Example 1 as follows. 0.935g of lithium bis(fluorosulfonyl)imide salt was added to 5ml of diethylene glycol dimethyl ether (DME) solvent and stirred thoroughly to form a colorless and transparent electrolyte solution with a concentration of 1M, which was used for the oxidation stability test and long-term cycling test of liquid metal lithium secondary batteries. Tests showed that the electrolyte had oxidation stability of 4 V. Referring to Figure 5, the liquid metal lithium secondary battery began to experience significant overcharging from the first cycle, with a cell with a rated capacity of 140 mAh being charged to 450 mAh and reaching the cutoff voltage, indicating obvious oxidative decomposition of the electrolyte.

[0111] Comparative Example 2 A fluorine-containing ether-based electrolyte solution of the prior art was prepared as follows, and tested with reference to Example 1. 0.935 g of lithium bis(fluorosulfonyl)imide salt was added to 5 ml of the solvent of formula I-2 and stirred thoroughly to form a colorless and transparent electrolyte solution with a concentration of 1 M, which was used for the oxidation stability test and the long-term cycling test of the liquid metal lithium secondary battery. Tests have shown that the electrolyte has an oxidation stability of 5.4 V. Referring to Figure 6, the liquid metal lithium secondary battery experienced a slight overcharge phenomenon in the cycle range of approximately 50-70 during cycling, but the impact on the discharge capacity within this range was small, and self-recovery was possible, resulting in a cycling life of 146 cycles.

[0112] Comparative Example 3 A prior art locally high concentration electrolyte solution was prepared and tested with reference to Example 1 as follows. Mix equal masses of diethylene glycol dimethyl ether (DME) and 1,1,2,2-difluoroethyl-2,2,3,3-difluoropropyl ether (TTE) and stir to form a colorless, transparent, homogeneous liquid for later use. Add 0.935 g of lithium bis(fluorosulfonyl)imide salt to 5 ml of the above-mentioned mixed solvent and stir thoroughly to form a colorless, transparent solution with a 1 M concentration. This will be used for subsequent performance testing and cell cycling. Tests showed that the electrolyte had an oxidation stability of 5.3 V. Referring to Figure 7, the liquid metal lithium secondary battery showed obvious overcharge phenomenon in the 40-60 cycle range during cycling, but the impact on the discharge capacity within this range was small, and self-recovery was possible, resulting in a cycling life of 110 cycles.

[0113] Comparative Example 4 A prior art locally high concentration electrolyte solution was prepared and tested with reference to Example 1 as follows. Mix equal masses of diethylene glycol diethyl ether (DEE) and 1,2-(1,1,2,2-tetrafluoroethoxy)-ethane (TFE) and stir to form a colorless, transparent, homogeneous liquid for later use. Add 0.935 g of lithium bis(fluorosulfonyl)imide salt to 5 ml of the above-mentioned mixed solvent and stir thoroughly to form a colorless, transparent solution with a 1 M concentration. This will be used for subsequent performance testing and cell cycling. Tests have shown that the electrolyte has an oxidation stability of 5.3 V. Referring to Figure 8, the liquid metal lithium secondary battery experienced an overcharge phenomenon in the 45-55 cycle range during cycling, but the impact on the discharge capacity within this range was small, and self-recovery was possible, resulting in a cycling life of 135 cycles.

[0114] Table 1 below shows the electrolytes and performance test results for Examples 1-16 and Comparative Examples 1-4.

[0115] [Table 1] *Here, "solvent mass ratio" refers to the mass ratio of the first solvent to the second solvent. Hereinafter, the same expressions have the same meaning.

[0116] As can be seen from Table 1, the electrolyte of the present invention can effectively avoid the "transient" overcharge problem during long-term cycling of secondary batteries, and also has a high oxidation stability critical voltage (i.e., high oxidation stability), which can extend the cycling life. The conventional ether-based electrolyte of Comparative Example 1 is difficult to cycle normally in a metallic lithium negative electrode-ternary positive electrode secondary battery, and as can be seen from Comparative Example 2, the use of a fluorine-containing solvent alone can improve oxidation stability, but cannot solve the overcharge problem during long-term cycling.

[0117] Examples 17-25 Example 17 differs from Example 1 in that a colorless and transparent solution with a concentration of 1M is prepared, and then lithium nitrate powder is added thereto, so that the weight ratio of the solution to lithium nitrate is 99:1, and the solution is added and thoroughly stirred to form a colorless and transparent electrolyte solution, which is the desired electrolyte solution. Examples 18-25 differ from Example 17 in that the weight ratio of the first and / or second solvents is different.

[0118] Examples 26-39 Examples 26 and 17 differ in that the first and second solvents are different, Examples 27-32 and 26 differ in that the weight ratios of the first and second solvents are different, Examples 33 and 17 differ in that the first and second solvents are different, and Examples 34-39 and 33 differ in that the weight ratios of the first and second solvents are different.

[0119] Examples 40-46 Examples 40-46 differ from Examples 17-25 in that different antioxidants were added.

[0120] Comparative Example 5 A conventional ether-based electrolyte solution containing an antioxidant additive was prepared as follows and tested with reference to Example 1. Add 0.935g of lithium bis(fluorosulfonyl)imide salt to 5ml of diethylene glycol dimethyl ether (DME) solvent, add 1% of the total mass of lithium nitrate powder, and stir thoroughly to form a 1M colorless, transparent electrolyte containing antioxidant additives, which can be used in oxidation stability tests and long-term cycling tests of liquid metal lithium secondary batteries. Testing revealed that the oxidation stability critical voltage of this electrolyte was 5.1 V. Referring to Figure 9, during cycling, the liquid metal lithium secondary battery exhibited obvious overcharge phenomenon in the 35-60 cycle range, and the discharge capacity was significantly affected in this range, with a cycling life of 92 cycles.

[0121] Comparative Example 6 A fluorine ether-based electrolyte solution containing an antioxidant additive was prepared as follows, and tested with reference to Example 1. 0.935 g of lithium bis(fluorosulfonyl)imide salt was added to 5 ml of the solvent of formula I-2, and 1% of the total mass of lithium nitrate powder was added. The mixture was thoroughly stirred to form a 1 M colorless and transparent electrolyte containing antioxidant additives, which was used in the oxidation stability test and long-term cycling test of liquid metal lithium secondary batteries. Testing showed that the electrolyte had an oxidation stability of 5.4 V. Referring to Figure 10, the liquid metal lithium secondary battery experienced a slight overcharge phenomenon in the 100-170 cycle range during cycling, but the impact on the discharge capacity within this range was small, and self-recovery was possible, resulting in a cycling life of 159 cycles.

[0122] Table 2 below shows the electrolytes and their performance test data in Examples 17-46 and Comparative Examples 5-6.

[0123] [Table 2-1] [Table 2-2]

[0124] As can be seen from Table 2, the electrolyte containing an antioxidant not only prevents overcharging, but also improves the oxidation stability of the electrolyte and extends the cycle life. As can be seen from Comparative Examples 3-4, the combination of a conventional ether solvent and an antioxidant does not provide the effect of preventing overcharging, while the combination of a fluorinated ether solvent and an antioxidant improves the oxidation resistance and cycle life, but does not prevent overcharging.

[0125] Examples 47-52 Examples 47-52 and Example 17 differ in the concentration of antioxidant added.

[0126] Examples 53-64 Examples 53-58 differ from Example 26 in that they contain different concentrations of antioxidants. Examples 59-64 differ from Example 33 in that they contain different concentrations of antioxidants.

[0127] Examples 65-70 Examples 65-70 and Example 17 differ in that the antioxidants added and their concentrations are different.

[0128] Examples 71-78 Examples 71-72 differ from Example 17 in that they have different electrolyte salt concentrations. Examples 73-74 differ from Example 26 in that they have different electrolyte salt concentrations. Examples 75-76 differ from Example 33 in that they have different electrolyte salt concentrations. Examples 77-78 differ from Examples 71-72 in that they contain different antioxidants.

[0129] Table 3 below shows the electrolytes of Examples 47-78 and the performance test results thereof.

[0130] [Table 3-1] [Table 3-2]

[0131] As can be seen from Table 3, the use of antioxidants in the above concentration ranges can further improve the oxidation stability and extend the cycle life.

[0132] As described above, the optimum performance can be achieved when the weight ratio of the first solvent to the second solvent is 1, the content of the antioxidant additive is 1%, and the concentration of the electrolyte salt is 1M.

[0133] The present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any embodiment that has substantially the same configuration as the technical idea and exhibits the same effects within the scope of the technical solution of the present application is included within the technical scope of the present application. Various modifications that a person skilled in the art can make to the embodiments without departing from the spirit of the present application, and other forms constructed by combining some of the components of the embodiments are also included within the scope of the present application. [Explanation of symbols]

[0134] 1 battery pack 2 Upper box 3 Lower box 4 battery modules 5 secondary battery 51 Housing 52 electrode assembly 53 Top cover assembly

Claims

1. An electrolyte solution, A first solvent, represented by Formula I: 【Chemistry 1】 however, R １ is selected from C1-C6 fluoro alkyl groups, R ２ is selected from a hydrogen atom, a C1-C6 alkyl chain and a C1-C6 fluoro alkyl chain, the first solvent, wherein n is 1 or 2; a second solvent selected from one or more of the compounds of Formula II and Formula III; 【Chemistry 2】 however, The solvent of formula II is selected from the following compounds: 【Transformation 3】 R 9 and R １０ are each independently selected from a hydrogen atom, a fluorine atom, a C1-C6 alkyl chain group, and a C1-C6 fluoro alkyl chain group.

2. In the formula I, R １ is selected from C1-C3 fluoro-chain alkyl groups, and / or R ２ 2. The electrolyte solution according to claim 1, wherein is selected from the group consisting of a hydrogen atom, a C1-C3 alkyl chain group and a C1-C3 fluoro alkyl chain group.

3. In Formula III, R ９ ~R １０ 2. The electrolyte solution according to claim 1, wherein each of is independently selected from a hydrogen atom, a fluorine atom, and a C1-C6 alkyl chain.

4. 2. The electrolytic solution according to claim 1, wherein the weight ratio of the first solvent to the second solvent is 0.5 to 3.

5. The electrolyte of claim 1 further comprising an antioxidant.

6. 6. The electrolyte according to claim 5, wherein the concentration of the antioxidant is 0.5% by weight to 3% by weight based on the total weight of the electrolyte.

7. The electrolytic solution according to claim 1 , further comprising a fluorine-containing electrolyte salt.

8. 8. The electrolytic solution according to claim 7, wherein the concentration of the fluorine-containing electrolyte salt is 0.5M to 3M.

9. A secondary battery comprising the electrolytic solution according to any one of claims 1 to 8.

10. A battery module comprising the secondary battery according to claim 9 .

11. A battery pack comprising the battery module according to claim 10.

12. A power consuming device comprising the secondary battery of claim 9.

Images