Electrolyte and lithium battery

Abstract

The invention provides an electrolyte and a lithium battery. Specifically, the electrolyte comprises an additive; wherein the additive comprises at least one compound shown as a formula (I): # imgabs0 #, and R1 is selected from at least one of H, halogen, substituted or unsubstituted alkyl and substituted or unsubstituted alkenyl. The electrolyte can meet the requirement of the battery cell for the fast charging performance and also considers the high-temperature performance at the same time.

Description

Technical Field

[0001] The present disclosure relates to the field of battery technology, and in particular to an electrolyte and a lithium battery. Background Art

[0002] With the widespread application of electrochemical energy storage in portable electronics and electric vehicles, the requirements and dependence on lithium-ion batteries have become higher than ever before. After decades of development, the main challenge for the widespread use of electric vehicles is "range anxiety" compared to traditional internal combustion engine vehicles. In order to provide a similar experience to traditional internal combustion engine vehicles, it usually takes 15 minutes to fully charge a battery for a range of about 400 kilometers. However, ultra-fast charging brings new challenges to battery materials, requiring further improvement in the transport of lithium ions in the electrolyte and the charge transfer kinetics at the electrode / electrolyte interface. Summary of the invention

[0003] In view of this, the purpose of the present disclosure is to provide an electrolyte and a lithium battery.

[0004] Based on the above purpose, the first aspect of the present disclosure provides an electrolyte, comprising an additive; wherein the additive comprises at least one compound of formula (I):

[0005]

[0006] Wherein, R1 is at least one selected from H, halogen, substituted or unsubstituted alkyl, and substituted or unsubstituted alkenyl.

[0007] In some embodiments, the substituents of the alkyl and alkenyl groups are each independently selected from halogen, -OH, -NO2, -CN, and -NH2.

[0008] In some embodiments, the alkyl group is selected from C1 to C8 alkyl groups; and / or the alkenyl group is selected from C2 to C8 alkenyl groups.

[0009] In some embodiments, based on the total mass of the electrolyte, the content of the additive is 0.1% to 3%, optionally 0.3% to 1%.

[0010] In some embodiments, the electrolyte further comprises carboxylic acid ester; based on the total mass of the electrolyte, the content of the carboxylic acid ester is greater than 50%.

[0011] In some embodiments, cyclic carbonate is further included; based on the total mass of the electrolyte, the content of the cyclic carbonate is less than 5%.

[0012] In some embodiments, a fluorinated cyclic carbonate is further included; based on the total mass of the electrolyte, the content of the fluorinated cyclic carbonate is 4% to 9%;

[0013] Optionally, the fluorinated cyclic carbonate includes fluorinated ethylene carbonate.

[0014] In some embodiments, the electrolyte further comprises a lithium salt, wherein the lithium salt comprises at least one of LiPF6 and LiFSI;

[0015] Optionally, based on the total mass of the electrolyte, the content of LiFSI is greater than the content of LiPF6.

[0016] Based on the same inventive concept, the second aspect of the present disclosure further provides a lithium battery, comprising any of the aforementioned electrolytes.

[0017] In some embodiments, the positive electrode active material of the lithium battery includes at least one of lithium iron phosphate, lithium nickel manganese oxide, lithium-rich manganese base, lithium iron manganese phosphate, lithium cobalt oxide and ternary materials; and / or

[0018] The negative electrode of the lithium battery includes at least one of graphite, silicon and silicon oxide.

[0019] It can be seen from the above that the present disclosure provides an electrolyte and a lithium battery, wherein the electrolyte includes an additive; wherein the additive includes at least one compound of formula (I): Wherein, R1 is selected from at least one of H, halogen, substituted or unsubstituted alkyl and substituted or unsubstituted alkenyl. In such a technical scheme, the compound of formula (I) can combine with lithium salts, change the solvation structure of lithium ions, and improve the conductivity of lithium ions; at the same time, the compound of formula (I) can decompose preferentially over other solvents, which is conducive to the formation of interface components rich in inorganic Li3N and Li-S compounds in the electrode interface film. These inorganic components can improve the ionic conductivity and thermal stability of the interface, improve the kinetic performance of the battery cell, and thus meet the battery cell's demand for fast charging performance while improving the interface stability at high temperatures. DETAILED DESCRIPTION

[0020] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific embodiments.

[0021] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present disclosure should have the common meanings understood by persons having ordinary skills in the field to which the present disclosure belongs.

[0022] The "range" used in the embodiments of the present disclosure is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The range defined in this way can be inclusive or exclusive of end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 130 and 70 to 120 is listed for a particular parameter, it is understood that a range of 60 to 120 and 70 to 130 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present disclosure, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, wherein a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0023] If not otherwise specified, all embodiments and optional embodiments of the present disclosure may be combined with each other to form a new technical solution.

[0024] Unless otherwise specified, all technical features and optional technical features of the present disclosure can be combined with each other to form a new technical solution.

[0025] If there is no special explanation, the "include" and "comprising" mentioned in the present disclosure may be open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or comprised, or may only include or comprise the listed components.

[0026] If not specifically stated, in the present disclosure, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B".

[0027] In the related art, in order to improve the charging efficiency of lithium batteries and achieve ultra-fast charging, a common method is to introduce carboxylic acid esters into the electrolyte. However, the introduction of carboxylic acid esters easily leads to a decrease in high-temperature performance, such as a decrease in high-temperature storage performance and high-temperature cycle performance.

[0028] Electrolyte

[0029] In view of this, an embodiment of the present disclosure provides an electrolyte, wherein the electrolyte includes an additive; wherein the additive includes at least one compound of formula (I): Wherein, R1 is selected from at least one of H, halogen, substituted or unsubstituted alkyl and substituted or unsubstituted alkenyl. Here, halogen can be F, Cl, Br, I, etc., which is not limited in the present disclosure. Alkyl can be a straight-chain alkyl, a branched-chain alkyl or a cycloalkyl. For example, a straight-chain alkyl can be a methyl, ethyl, butyl, etc.; a branched-chain alkyl can be an isopropyl, isobutyl, tert-butyl, etc.; a cycloalkyl can be a cyclohexyl, cyclopropyl, cyclobutyl, etc., which is not limited in the present disclosure. Here, alkenyl can be a vinyl, a propenyl, etc., which is not limited in the present disclosure.

[0030] The electrolyte provided by the present disclosure can improve the fast charging performance of lithium batteries while taking into account the high temperature cycle and high temperature storage performance, which helps the lithium batteries to operate stably for a long time. Here, the lithium battery can be a primary lithium battery or a secondary lithium battery, which is not limited in the present disclosure.

[0031] The compound of formula (I) containing S, N and O can combine with lithium salts, change the solvation structure of lithium ions, and improve the lithium ion conductivity; at the same time, the compound of formula (I) can decompose preferentially before other solvents, which is beneficial to the formation of interface components rich in inorganic Li3N and Li-S compounds in the electrode interface film. These inorganic components can improve the ionic conductivity and thermal stability of the interface, improve the kinetic performance of the battery cell, thereby meeting the battery cell's requirements for fast charging performance while improving the interface stability at high temperatures.

[0032] In some embodiments, the substituents of the alkyl and alkenyl groups are each independently selected from halogen, -OH, -NO2, -CN, and -NH2.

[0033] In some embodiments, the alkyl group is selected from C1-C8 alkyl groups, such as C1-C6 alkyl groups and C1-C4 alkyl groups. In some embodiments, the alkenyl group is selected from C2-C8 alkenyl groups, such as C2-C6 alkenyl groups, C2-C5 alkenyl groups and C2-C4 alkenyl groups.

[0034] It should be understood that the more carbon atoms the alkyl or alkenyl group has, the lower the relative content of S, N and O in formula (I), and the lower the number of inorganic components formed in the electrode interface film. Alkyl and alkenyl groups of C1 to C8 are conducive to ensuring that the compound of formula (I) effectively improves fast charging performance while taking into account high temperature performance.

[0035] In some embodiments, based on the total mass of the electrolyte, the content of the additive is 0.1% to 3%, such as 0.1%, 0.14%, 0.2%, 0.52%, 1.13%, 1.5%, 2.15%, 2.4%, 3%; optionally, 0.3% to 1%. If the content of the additive is lower than 0.1%, it is difficult to improve the fast charging performance and ensure the high temperature cycling performance; if the content of the additive is higher than 3%, the ability to improve the high temperature performance is weakened.

[0036] In some embodiments, cyclic carbonate is further included; based on the total mass of the electrolyte, the content of the cyclic carbonate is less than 5%, such as 2%, 3%, 4%, etc.

[0037] Exemplarily, the cyclic carbonate includes at least one of propylene carbonate (PC) and ethylene carbonate (EC). Cyclic carbonates have a relatively high dielectric constant, which helps to dissolve lithium salts and make them evenly distributed in the electrolyte, thereby improving the dynamic performance of lithium batteries. Among them, a low content of EC can reduce the viscosity of the electrolyte and can also improve the dynamic performance of lithium batteries. When the content of cyclic carbonate is greater than 5%, for example 10%, it can still reduce the DC internal resistance of the lithium battery and improve the high-temperature cycle stability and storage performance of the lithium battery, but the improvement effect is weaker than when the content of cyclic carbonate is less than 5%.

[0038] In some embodiments, a fluorinated cyclic carbonate is also included. Optionally, the fluorinated cyclic carbonate includes fluorinated ethylene carbonate (FEC). Further, based on the total mass of the electrolyte, the content of the fluorinated cyclic carbonate is 4% to 9%, for example, 4%, 5%, 7%, 9%, etc. The above-mentioned content of FEC can make up for the problem of lithium salt solution caused by low content of EC, and FEC can participate in film formation to improve the cycle performance of lithium-ion batteries.

[0039] In some embodiments, carboxylic acid esters are also included, such as methyl acetate (MA), ethyl acetate (EA), ethyl propionate (EP), propyl acetate (PA), propyl propionate (PP), etc. Further, based on the total mass of the electrolyte, the content of the carboxylic acid ester is greater than 50%, such as 60%, 70%, 75%, 80%, etc. Here, a high content of carboxylic acid ester can further reduce the viscosity of the electrolyte, increase the conductivity, and thus improve the kinetic performance of the lithium-ion battery.

[0040] It should be noted that different carboxylates can be added to the electrolyte individually or in combination, and the present disclosure does not limit this.

[0041] In some embodiments, the electrolyte further includes a lithium salt, and the lithium salt includes at least one of LiPF6 and LiFSI. Optionally, based on the total mass of the electrolyte, the content of LiFSI is greater than the content of LiPF6. Here, replacing part of LiPF6 with LiFSI can effectively improve the kinetic performance of the lithium-ion battery.

[0042] Lithium battery

[0043] A second aspect of the present disclosure provides a lithium battery, comprising the electrolyte provided in the above disclosure.

[0044] In some embodiments, the lithium battery includes a positive electrode sheet, a negative electrode sheet, a separator between the positive electrode sheet and the negative electrode sheet, and an electrolyte. During the battery charging and discharging process, active ions are embedded and extracted back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.

[0045] Positive electrode

[0046] 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, wherein the positive electrode film layer includes a positive electrode active material.

[0047] Exemplarily, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0048] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (e.g., polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0049] In some embodiments, the positive electrode active material includes at least one of lithium iron phosphate (LiFePO4), lithium nickel manganese oxide, lithium manganese-rich base, lithium manganese iron phosphate, lithium cobalt oxide (LCO) and a ternary material.

[0050] For ternary materials, it can be lithium nickel cobalt manganese oxide (LiN x Co y Mn z O2, and x+y+z=1), such as LiNi 1 / 3Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM211), LiNi 0.6 Co 0.2 Mn 0.2O2 (also referred to as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM811).

[0051] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0052] In some embodiments, the positive electrode film layer may further include a conductive agent, which may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0053] In some embodiments, the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0054] Negative electrode

[0055] The negative electrode sheet includes a negative electrode current collector and a film layer optionally disposed on at least one surface of the negative electrode current collector.

[0056] Illustratively, the film layer may include a negative electrode active material, a conductive agent, a thickener, and a binder.

[0057] In some embodiments, the negative electrode active material may be at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon, and silicon oxide, for example, a mixture of graphite and silicon, a mixture of graphite and silicon oxide.

[0058] In some embodiments, the negative electrode sheet can be prepared in the following manner: the negative electrode active material, the conductive agent, the thickener, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0059] Isolation film

[0060] In some embodiments, the secondary battery further includes a separator. The present disclosure has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.

[0061] In some embodiments, the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0062] Example

[0063] Hereinafter, embodiments of the present disclosure are described. The embodiments described below are exemplary and are only used to explain the present disclosure, and should not be construed as limiting the present disclosure. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in the art or the product instructions are used. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0064] Example 1 to Example 22

[0065] (1) Preparation of positive electrode:

[0066] The positive electrode active material LiFePO4, the conductive agent acetylene black, and the binder polyvinylidene fluoride are dissolved in NMP at a mass ratio of 95:3:2 to form a slurry, which is then coated on an aluminum foil, dried, rolled, and cut to obtain a positive electrode sheet;

[0067] (2) Preparation of graphite negative electrode:

[0068] The negative electrode active material is artificial graphite, the conductive agent is acetylene black, and the binder is sodium carboxymethyl cellulose (CMC-Na). The negative electrode active material, the conductive agent, and the binder are added to deionized water in a mass ratio of 96:2:2 to obtain a mixed slurry, which is then coated on a copper foil, dried, rolled, and cut to obtain a negative electrode sheet.

[0069] (3) Preparation of electrolyte:

[0070] In an argon atmosphere glove box with a water content of <10 ppm, the solvents are mixed and stirred according to the proportions in Examples 1 to 22 to form a total organic solvent, lithium salt is added to the mixed solvent under stirring, stirring is continued until the lithium salt is completely dissolved, and finally the additive is added to the solution and stirred evenly.

[0071] Here, the ratio of lithium salt, additive and solvent in Examples 1 to 22 is shown in Table 1.

[0072] It should be noted that the additives of Examples 1 to 19 are as follows: Formula (I-1);

[0073] The additives of Example 20 are as follows:

[0074] The additives of Example 21 are as follows:

[0075] The additives of Example 22 are as follows:

[0076] The mass percentages of lithium salts and additives in Table 1 are calculated based on the total mass of the electrolyte. EMC in Table 1 represents ethyl methyl carbonate.

[0077] (4) Preparation of batteries:

[0078] Using polypropylene film as a separator, the negative electrode, separator, and positive electrode prepared above are stacked in order and placed in an aluminum-plastic film to obtain a dry cell, and the dry cell is baked at 80°C to remove water. The electrolyte is injected into the dry cell and packaged to obtain a finished lithium-ion battery.

[0079] Comparative Example 1 to Comparative Example 2

[0080] The difference between Comparative Examples 1 to 4 and Example 1 is the composition of the electrolyte in step (3), as shown in Table 1.

[0081] Table 1

[0082]

[0083] Test Method

[0084] The lithium batteries prepared in the above embodiments and comparative examples can be tested by the following method:

[0085] (1) Cycle test, the test method is as follows:

[0086] At 45°C, charge the lithium-ion battery at 1 / 3C constant current to 4.35V, then charge at constant voltage to a current of 0.05C. Then discharge the battery at 1 / 3C constant current to 2.5V, record the capacity C0, repeat the above charge and discharge steps 800 times, and record the discharge capacity C1 of 800 cycles. The capacity retention rate of the battery = C1 / C0×100%.

[0087] (2) Direct Current Resistance (DCR) test. The test method is as follows:

[0088] At 25°C, charge the lithium-ion battery at 1 / 3C constant current to 4.35V, then charge at constant voltage to a current of 0.05C. Then discharge the battery at 1 / 3C constant current to 2.5V. Repeat the above charging steps and record the charging capacity as C2. Discharge the battery at 1 / 3C constant current to (50%×C2), record the initial voltage as V2. Discharge the battery at 1C2 constant current for 30s, record the terminal voltage as V3. DCR=(V2-V3) / (C2×1).

[0089] (3) High temperature storage test, the test method is as follows:

[0090] The lithium-ion battery was stored at 60°C for 60 days. The battery was then placed at 25°C and discharged at a constant current of 1 / 3C to 2.5V. The battery was then charged at a constant current of 1 / 3C to 4.35V, and then charged at a constant voltage to a current of 0.05C. The battery was then discharged at a constant current of 1 / 3C to 2.5V, and the discharge capacity was recorded as C3. The capacity recovery rate is (C3 / C2)×100%.

[0091] The test results are shown in Table 2.

[0092] Table 2

[0093]

[0094] Comparing Comparative Example 1, Example 1, and Examples 20 to 22, it can be seen that the addition of compounds of Formula (I-1) to (I-3) can not only reduce the DC internal resistance of the battery cell, which helps to achieve fast charging, but also improve the high-temperature storage performance and high-temperature cycle performance of the battery cell. The addition of the compound of Formula (I-4) increases the ethylene substitution impedance, which increases the DC internal resistance, but it can also improve the high-temperature storage performance and high-temperature cycle performance of the battery cell.

[0095] Comparing Examples 1 to 4, it can be seen that, under the premise that the content of cyclic carbonate does not exceed 4% of the total mass of the electrolyte, the addition of cyclic carbonate helps to reduce the DC internal resistance.

[0096] Comparison of Comparative Example 2, Example 5 and Example 9 shows that the addition of the compound of formula (I-1) can significantly improve the high temperature storage performance and high temperature cycle performance of the battery. Comparison of Example 5 and Example 9 shows that increasing the amount of LiFSI added increases the DC internal resistance but the levels are similar, and the high temperature storage performance and high temperature cycle performance of the battery remain basically unchanged, with good overall performance.

[0097] Comparing Example 1 with Example 18, it can be seen that when the carboxylate content is below 50%, the DC internal resistance of the battery cell increases significantly, which is not conducive to fast charging. This may be because the reduction in the carboxylate content increases the viscosity of the electrolyte and reduces the conductivity, which affects the dynamic performance of the battery cell.

[0098] Comparing Examples 5 to 8 with Example 18, it can be seen that when the mass percentage of carboxylic acid ester in the electrolyte is greater than 50%, the combination of different carboxylic acid esters can reduce the DC internal resistance of the battery cell, and the degree of reduction of the DC internal resistance of the battery cell by different carboxylic acid ester combinations is different. Among them, the combination of EA and MA has the most significant effect on reducing the DC internal resistance of the battery cell.

[0099] Comparing Comparative Example 2, Example 5, and Example 10 to Example 13, it can be seen that the addition of the compound of formula (I-1) helps to improve the high temperature performance of the battery. Specifically, with the increase in the mass percentage of the compound of formula (I-1), the degree of improvement in the high temperature performance of the battery shows a trend of first increasing and then decreasing. Among them, when the mass percentage of the compound of formula (I-1) is added at 0.3% and 1%, the DC internal resistance of the battery increases slightly, and the high temperature storage performance and high temperature cycling performance are significantly improved. When the mass percentage is 0.5%, the high temperature storage performance and high temperature cycling performance are significantly improved while the DC internal resistance of the battery remains stable.

[0100] Comparing Comparative Example 1, Example 1 and Example 14, it can be seen that the electrolytes of Example 1 and Example 14 can reduce the DC internal resistance of the battery cell and improve the high temperature storage performance and high temperature cycle performance of the battery cell. Compared with the electrolyte in Example 1 in which the content of the cyclic carbonate is less than 5%, the electrolyte in Example 14 in which the content of the cyclic carbonate is greater than 5% has a weaker improvement on the DC internal resistance and high temperature storage performance of the battery cell, and a slightly enhanced improvement on the high temperature cycle performance.

[0101] Comparing Example 1 with Examples 15 to 17, it can be seen that the amount of FEC added has a significant effect on the DC internal resistance of the battery cell. When the mass content of FEC added in the electrolyte is between 4% and 9%, the DC internal resistance of the battery cell is significantly reduced. Beyond this range, the improvement of the DC internal resistance decreases, and the improvement of high temperature performance is also slightly reduced.

[0102] Comparing Example 1 with Example 19, it can be seen that LiFSI is more helpful in reducing the DC internal resistance of the battery cell than LiPF6. This may be because the fluoride ions of LiFSI have strong electron-withdrawing properties, which weakens the coordination effect between anions and cations of the lithium salt and makes the activity of lithium ions stronger.

[0103] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present disclosure (including the claims) is limited to these examples. Based on the concept of the present disclosure, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present disclosure as described above, which are not provided in detail for the sake of simplicity.

[0104] The embodiments of the present disclosure are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present disclosure should be included in the scope of protection of the present disclosure.

Claims

1. An electrolyte, characterized in that: Including additives; wherein the additives include at least one compound of formula (I): Wherein, R1 is at least one selected from H, halogen, substituted or unsubstituted alkyl, and substituted or unsubstituted alkenyl.

2. The electrolyte according to claim 1, characterized in that The substituents of the alkyl group and the alkenyl group are each independently selected from halogen, -OH, -NO2, -CN and -NH2.

3. The electrolyte according to claim 1 or 2, characterized in that The alkyl group is selected from C1 to C8 alkyl groups; and / or the alkenyl group is selected from C2 to C8 alkenyl groups.

4. The electrolyte according to claim 1, characterized in that Based on the total mass of the electrolyte, the content of the additive is 0.1% to 3%, optionally 0.3% to 1%.

5. The electrolyte according to claim 1, characterized in that It also includes carboxylic acid ester; based on the total mass of the electrolyte, the content of the carboxylic acid ester is greater than 50%.

6. The electrolyte according to claim 1, characterized in that The electrolyte further comprises cyclic carbonate; based on the total mass of the electrolyte, the content of the cyclic carbonate is less than 5%.

7. The electrolyte according to claim 1, characterized in that It also includes a fluorinated cyclic carbonate; based on the total mass of the electrolyte, the content of the fluorinated cyclic carbonate is 4% to 9%; Optionally, the fluorinated cyclic carbonate includes fluorinated ethylene carbonate.

8. The electrolyte according to any one of claims 1 to 7, characterized in that: The electrolyte further includes a lithium salt, wherein the lithium salt includes at least one of LiPF6 and LiFSI; Optionally, based on the total mass of the electrolyte, the content of LiFSI is greater than the content of LiPF6.

9. A lithium battery comprising the electrolyte according to any one of claims 1 to 8.

10. The lithium battery according to claim 9, characterized in that: The positive electrode active material of the lithium battery includes at least one of lithium iron phosphate, lithium nickel manganese oxide, lithium-rich manganese base, lithium iron manganese phosphate, lithium cobalt oxide and ternary materials; and / or The negative electrode of the lithium battery includes at least one of graphite, silicon and silicon oxide.

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