Electrolyte additive, electrolyte, battery, battery module, and electric device

Abstract

The present application relates to an electrolyte additive. The electrolyte additive contains a sulfate compound; and the chemical formula of the sulfate compound is: (I), wherein R1 is selected from a halogen atom, and R2, R3, and R4 are each independently selected from one or more of a hydrogen atom, a halogen atom, C1-C6 alkyl, and C1-C6 fluoroalkyl.

Description

Electrolyte additives, electrolytes, batteries, battery modules and electrical devices

[0001] Related applications

[0002] This application claims priority to Chinese patent application No. 202311098288.6, filed on August 29, 2023, entitled “Electrolyte Additive for Batteries, Electrolyte and Battery Including Same,” the entire text of which is hereby incorporated by reference. Technical Field

[0003] The present application relates to the field of electrolyte technology, and in particular to an electrolyte additive, an electrolyte, a battery, a battery module and an electrical device. Background Art

[0004] The electrolyte is a crucial component of lithium-ion batteries, responsible for transferring charge between the positive and negative electrodes. It is crucial to the battery's capacity, operating temperature, cycle efficiency, and safety. In conventional technologies, the electrochemical window of the electrolyte system is narrower than that of the positive and negative electrode active materials. Consequently, the organic solvent in the electrolyte decomposes during the initial charge and discharge process, forming an unstable SEI (solid electrolyte interface) passivation film, resulting in poor battery performance. By adding a small amount of additives to the electrolyte, the additives preferentially decompose during the formation phase to participate in SEI film formation, inhibiting electrolyte decomposition and significantly improving battery performance. However, the solvents contained in the electrolytes currently used in commercial lithium-ion batteries are largely incapable of forming a stable solid electrolyte interface (SEI) film. During use, they intercalate with the solvated lithium ions into the graphite interlayers and decompose on the surface of highly graphitized carbon electrode materials, causing the graphite layers to peel off. This results in reduced cycle performance and poor rate capability for lithium-ion batteries.

[0005] Therefore, providing an electrolyte additive that can form a stable SEI film and reduce battery side reactions has become a technical problem that urgently needs to be solved.

[0006] Summary of the Invention

[0007] According to various embodiments of the present application, an electrolyte additive, an electrolyte, a battery, a battery module, and an electrical device are provided.

[0008] In a first aspect, the present application provides an electrolyte additive, wherein the electrolyte additive comprises a sulfate ester compound, and the chemical formula of the sulfate ester compound is:

[0009] Wherein, R1 is selected from a halogen atom, and R2, R3 and R4 are independently selected from one or more of a hydrogen atom, a halogen atom, a C1-C6 alkyl group or a C1-C6 fluoroalkyl group.

[0010] In some embodiments, R1 in the chemical formula of the sulfate ester compound is a fluorine atom.

[0011] In some embodiments, the sulfate compound comprises:

[0012] At least one of .

[0013] In a second aspect, the present application provides an electrolyte, which includes a lithium salt, a solvent and an additive, wherein the additive includes the electrolyte additive for the battery as described in the first aspect.

[0014] In some embodiments, the electrolyte additive for a battery has a content of about 0.5% to about 1.5% by weight in the electrolyte.

[0015] In some embodiments, the mass content of the lithium salt in the electrolyte is about 0.5 mol / L to about 3 mol / L.

[0016] In some embodiments, the lithium salt includes at least one of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide.

[0017] In some embodiments, the solvent includes at least one of propylene carbonate, ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, butylene carbonate, methylpropyl carbonate, dioxolane, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, methyl acetate, ethyl acetate, dimethyl sulfoxide, and sulfolane.

[0018] In some embodiments, the additives further include functional additives.

[0019] In some embodiments, the functional additive includes at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propane sultone, 1,3-propylene sultone, lithium difluorophosphate, and lithium difluorooxalatoborate.

[0020] In some embodiments, the functional additive is present in the electrolyte in an amount of about 0.1% to about 2% by weight.

[0021] In a third aspect, the present application provides a battery comprising a positive electrode, a negative electrode, a separator and the electrolyte as described in the second aspect.

[0022] In some embodiments, the battery is a lithium-ion battery.

[0023] In a fourth aspect, the present application provides a battery module, comprising: a plurality of batteries connected in series and / or in parallel, wherein at least one battery is the battery as described in the third aspect.

[0024] In a fifth aspect, the present application provides an electrical device, which includes: a battery module as described in the fourth aspect or a single battery as described in the third aspect.

[0025] The details of one or more embodiments of the present application are set forth in the description below. Other features, objects, and advantages of the present application will become apparent from the description and claims. DETAILED DESCRIPTION

[0026] To facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant embodiments. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0028] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to an integer in the numerical interval, including the two endpoint integers of the numerical range, and each integer between the two endpoints, is equivalent to directly enumerating each integer. When multiple numerical ranges are provided to describe a feature or characteristic, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical range disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows broadly including quantitative intervals such as percentage intervals, ratio intervals, and ratio intervals.

[0029] In this application, the terms "optionally," "optional," and "optional" mean optional or dispensable, i.e., they refer to either option being selected from two parallel options: "with" or "without." If a technical solution contains multiple "optional" clauses, each "optional" clause is independent unless otherwise specified and there are no contradictions or constraints.

[0030] In this application, the terms "first," "second," and "third," etc., in "the first aspect," "the second aspect," "the third aspect," etc., are used for descriptive purposes only and should not be understood as indicating or implying relative importance or quantity, nor as implicitly indicating the importance or quantity of the technical features indicated. Furthermore, "first," "second," and "third," etc., are only used for non-exhaustive enumeration and description purposes and should be understood not to constitute closed-ended limitations on quantity.

[0031] The term "alkyl" refers to a saturated hydrocarbon containing primary (normal) carbon atoms, secondary carbon atoms, tertiary carbon atoms, quaternary carbon atoms, or combinations thereof. Phrases containing this term, for example, "C1-C6 alkyl" refers to an alkyl group containing 1 to 6 carbon atoms, each occurrence of which can independently be C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, or C6 alkyl. Suitable examples include, but are not limited to, methyl (Me, -CH3), ethyl (Et, -CH2CH3), 1-propyl (n-Pr, n-propyl, -CH2CH2CH3), 2-propyl (i-Pr, i-propyl, -CH(CH3)2), 1-butyl (n-Bu, n-butyl, -CH2CH2CH2CH3), 2-methyl-1-propyl (i-Bu, i-butyl, -CH2CH(CH3)2), 2-butyl (s-Bu, s-butyl, -CH(CH3)CH2CH3), 2-methyl-2-propyl (t- Bu, t-butyl, -C(CH3)3), 1-pentyl (n-pentyl, -CH2CH2CH2CH2CH3), 2-pentyl (-CH(CH3)CH2CH2CH3), 3-pentyl (-CH(CH2CH3)2), 2-methyl-2-butyl (-C(CH3)2CH2CH3), 3-methyl-2-butyl (-CH(CH3)CH(CH3)2), 3-methyl-1-butyl (-CH2CH2CH(CH3)2), 2-methyl-1-butyl (-CH2CH(CH3)CH2CH3).

[0032] The term "fluoroalkyl" refers to a compound in which one or more hydrogen atoms in the above saturated hydrocarbons containing primary (normal) carbon atoms, secondary carbon atoms, tertiary carbon atoms, quaternary carbon atoms, or combinations thereof are substituted by fluorine atoms. Non-limiting examples of “C1-C6 fluoroalkyl” include, but are not limited to: -CH2F, -CHF2, -CF3, -CH2CH2F, -CH2CHF2, -CH2CF3, -CHFCH3, -CF2CH3, -CHFCH2F, -CF2CH2F, -CF2CHF2, -CF2CF3, -CH2CH2CH2F, -CH2CH2CHF2, -CH2CH2CF3, -CH2CF2CH3, -CH2CHFCH3, -CHFCH2CH3, -CF2CH2CH3, -CF2CHFCH3, -CF2CF2CH3, -CF2CF2CH3, -CF2CF2CH2F, -CF2CH2CHF2, -CF2CH2CF3, -CF2CF2CH2F, -CF2CF2CHF2, -CF2CF2CF3, etc.

[0033] The term "halogen atom" refers to F, Cl, Br or I.

[0034] In conventional lithium-ion battery electrolytes, most solvents cannot form a stable solid electrolyte interface (SEI) film. During use, they are embedded in the graphite interlayer of the negative electrode material together with the solvated lithium ions and decompose on the surface of the highly graphitized carbon electrode material, causing the graphite layer to peel off, resulting in a decrease in the cycle performance of the lithium-ion battery and poor rate performance. However, the electrolyte additives used in this application can decompose during the formation stage to participate in the formation of the negative electrode SEI film, inhibiting the side reaction decomposition of the organic solvent in the electrolyte, thereby significantly improving the high-temperature cycle and storage performance of the battery.

[0035] In a first aspect, the present application provides an electrolyte additive, wherein the electrolyte additive comprises a sulfate ester compound, and the chemical formula of the sulfate ester compound is:

[0036] Wherein, R1 is selected from a halogen atom, and R2, R3 and R4 are independently selected from one or more of a hydrogen atom, a halogen atom, a C1-C6 alkyl group or a C1-C6 fluoroalkyl group.

[0037] The electrolyte additive in this application decomposes during the formation stage to participate in the SEI film formation of the negative electrode, and can form a more stable and conductive SEI passivation film containing lithium sulfonate (RSO3Li) and lithium sulfate (Li2SO4) with the negative electrode, and inhibit the side reaction decomposition of the electrolyte organic solvent. Moreover, during the battery cycle and storage process, it can improve the interface stability and inhibit the irreversible consumption of capacity caused by the side reaction decomposition of the electrolyte, significantly inhibit the gas production of the electrolyte side reaction during the charge and discharge process of the battery and reduce the impedance, thereby improving the high-temperature cycle and storage performance of the battery.

[0038] In some embodiments, R1 in the chemical formula of the sulfate ester compound is a fluorine atom.

[0039] In the present application, R1 is preferably a fluorine atom. The use of fluorinated sulfate compounds can form more lithium fluoride in the process of forming the SEI passivation film. The high stability of lithium fluoride helps to improve the SEI film, thereby increasing the cycle performance.

[0040] In some embodiments, the sulfate compound comprises:

[0041] At least one of .

[0042] The compounds in formulas 1-6 can be synthesized using known methods. For example, the compound in formula 1 can be prepared by reacting 1,1,2,2-tetrafluoroethylene with sulfur trioxide, as shown in the following chemical reaction formula:

[0043] The reaction conditions are first reacting at 0-12°C for 2h and then reacting at 60°C for 2h.

[0044] The compounds of formula 2 to formula 6 can be prepared by reacting ethylene substituted with different fluorine groups with sulfur trioxide.

[0045] In a second aspect, the present application provides an electrolyte, which includes a lithium salt, a solvent, and an additive, wherein the additive includes the electrolyte additive for the battery as described in the first aspect.

[0046] In some embodiments, the mass content of the electrolyte additive for the battery in the electrolyte is about 0.5% to about 1.5%, for example, it can be about 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4% or 1.5%.

[0047] The present application controls the content of the electrolyte additive to ensure that the formed SEI film is stable and conductive. If the content of the electrolyte additive is relatively high, the SEI film may be thick, resulting in high impedance and unstable gas generation caused by residual additives. If the content of the electrolyte additive is relatively low, the additive content may prevent the film from forming completely and the film may be unstable.

[0048] In some embodiments, the molar concentration of the lithium salt in the electrolyte is about 0.5 mol / L to about 3 mol / L, for example, about 0.5 mol / L, 0.6 mol / L, 0.8 mol / L, 1.0 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2.0 mol / L, 2.2 mol / L, 2.4 mol / L, 2.6 mol / L, 2.8 mol / L or 3.0 mol / L.

[0049] In some embodiments, the lithium salt includes at least one of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide.

[0050] In some embodiments, the solvent includes at least one of propylene carbonate, ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, butylene carbonate, methylpropyl carbonate, dioxolane, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, methyl acetate, ethyl acetate, dimethyl sulfoxide, and sulfolane.

[0051] In some embodiments, the additives further include functional additives.

[0052] In some embodiments, the functional additive includes at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propane sultone, 1,3-propylene sultone, lithium difluorophosphate, and lithium difluorooxalatoborate.

[0053] In some embodiments, the mass content of the functional additive in the electrolyte is about 0.1% to about 2%, for example, it can be about 0.1%, 0.2%, 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, 1.8% or 2.0%.

[0054] A third aspect of the present application provides a battery, comprising a positive electrode, a negative electrode, a separator, and the electrolyte as described in the second aspect.

[0055] It will be appreciated that the battery can be prepared and used according to conventional methods known in the art.

[0056] In some embodiments, the battery may be a lithium-ion battery.

[0057] In some embodiments, the method for preparing a battery in the present application includes:

[0058] (1) Positive electrode

[0059] The preparation method of the positive electrode includes coating a positive electrode current collector with a positive electrode slurry containing a positive electrode active material, a binder, a conductive agent, and a solvent, and then drying and roll-pressing the coated positive electrode current collector.

[0060] There is no particular limitation on the positive electrode current collector material as long as it is conductive and does not cause adverse chemical changes in the battery. For example, stainless steel, aluminum, nickel, titanium, fired carbon, or aluminum or stainless steel surface-treated with one of carbon, nickel, titanium or silver can be used.

[0061] In a preferred embodiment, the positive electrode current collector is selected from aluminum current collector.

[0062] The positive electrode active material is a compound that reversibly intercalates and deintercalates lithium. The positive electrode active material in this application can be any positive electrode active material known in the art. Alternatively, the positive electrode active material can be a lithium iron phosphate material or a nickel-cobalt-manganese ternary positive electrode material.

[0063] The positive electrode active material content may be about 80% to about 99% by weight based on the total weight of the solid components in the positive electrode slurry. If the positive electrode active material content is less than 80% by weight, the energy density may be reduced, and thus the capacity may be reduced.

[0064] The binder is a component that facilitates adhesion between the active material and the conductive agent, as well as adhesion to the current collector. The binder content is about 1% to about 30% by weight based on the total weight of the solid components in the positive electrode slurry. The binder may include, but is not limited to, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and various copolymers.

[0065] The conductive agent is a material that provides electrical conductivity without causing adverse chemical changes in the battery. The conductive agent may be present in an amount of 1% to 20% by weight based on the total weight of the solid components in the positive electrode slurry. The conductive agent may include, but is not limited to, carbon powder such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; graphite powder such as natural graphite, artificial graphite, or graphite having a well-grown crystal structure; conductive fibers such as carbon fibers or metal fibers; conductive powders such as fluorocarbon powder, aluminum powder, and nickel powder; conductive whiskers such as zinc oxide whiskers and potassium titanate whiskers; conductive metal oxides such as titanium oxide; or polyphenylene derivatives.

[0066] The solvent may include water or an organic solvent such as N-methyl-2-pyrrolidone (NMP) and an alcohol, and may be used in an amount such that a desired viscosity is obtained when the positive electrode active material and an optional binder and a conductive agent are included. For example, the solvent may be present in an amount such that the concentration of the solid component in the slurry containing the positive electrode active material and an optional binder and a conductive agent is from about 10 wt % to about 60 wt %, for example, from about 20 wt % to about 50 wt %.

[0067] (2) Negative electrode

[0068] The negative electrode may be prepared by coating a negative electrode current collector with a negative electrode slurry comprising a negative electrode active material, a binder, a conductive agent, and a solvent, and then drying and roll-pressing the coated negative electrode current collector.

[0069] The negative electrode current collector typically has a thickness of about 3 μm to about 500 μm. There are no particular limitations on the negative electrode current collector, as long as it has high conductivity and does not cause adverse chemical changes in the battery. For example, copper, stainless steel, aluminum, nickel, titanium, fired carbon, or copper or stainless steel surface-treated with one of carbon, nickel, titanium, or silver, or an aluminum-cadmium alloy, etc., can be used. Furthermore, similar to the positive electrode current collector, the negative electrode current collector can have various shapes, such as rods, plates, sheets, and foils.

[0070] The negative electrode active material described in the present application can be any negative electrode active material known in the art, for example, including but not limited to metallic lithium, graphite, natural graphite, artificial graphite, hard carbon, soft carbon, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, tin-based composite materials, spinel-structured lithiated TiO2, Li4Ti5O 12 , Li-Al alloy, silicon, Li-Si alloy, Li-Si-O alloy, silicon-based composite material, one or more of tin-silicon composite material.

[0071] The negative electrode active material may have a mass content of 80% to 99% based on the total weight of the solid components in the negative electrode slurry.

[0072] Similar to the binder, conductive agent, and solvent in the positive electrode, the amount of the binder, conductive agent, and solvent in the negative electrode is calculated based on the total weight of the solid components in the negative electrode slurry. Their specific content, function, and type are the same as those of the binder, conductive agent, and solvent in the positive electrode and are not further described here. Those skilled in the art can select the binder, conductive agent, and solvent suitable for the negative electrode according to actual needs.

[0073] (3) Diaphragm

[0074] The diaphragms commonly used in lithium-ion batteries are selected, such as porous polymer films prepared from polyolefin polymers such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer, which can be used as diaphragms alone or laminated together to be used as diaphragms in the lithium-ion batteries of the present application. Non-woven fabrics formed of polyester fibers, aramid fibers, glass fibers, etc. can also be used; as well as base membranes formed by ceramic particles such as silica, alumina, and titanium dioxide attached to their surfaces, etc.

[0075] A fourth aspect of the present application provides a battery module comprising: a plurality of batteries connected in series and / or in parallel, wherein at least one battery is the battery as described in the third aspect.

[0076] The fifth aspect of the present application provides an electrical device, comprising: the battery module as described in the fourth aspect or a single battery as described in the third aspect. The electrical device of the present application can be any device using the battery module or battery provided in the embodiments of the present application.

[0077] In some embodiments, the electrical devices include, but are not limited to: laptop computers, pen-type computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, head-mounted stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini-discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries or lithium-ion capacitors, etc.

[0078] The embodiments of the present application will be described in detail below with reference to the examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are preferably referred to the guidance provided in the present application, and can also be based on the experimental manuals or conventional conditions in this area, or according to the conditions recommended by the manufacturer, or with reference to experimental methods known in the art.

[0079] In the following examples and comparative examples, LiFePO4: carbon black: carboxymethyl cellulose were mixed into a uniform slurry in a mass ratio of 92:5:3 and coated on an aluminum foil current collector with a thickness of about 13 μm to form a positive electrode active material with an area density of about 164 g / m 2 , as the positive electrode.

[0080] Graphite: carbon black: carboxymethyl cellulose were mixed into a uniform slurry in a mass ratio of 93:2:5 and coated on a copper foil current collector with a thickness of about 6 μm to form a negative electrode active material with a surface density of about 80.2 g / m 2, as the negative electrode;

[0081] The separator used was a polyethylene separator having a thickness of about 12 μm.

[0082] Example 1

[0083] (1) Electrolyte

[0084] Ethylene carbonate and dimethyl carbonate are uniformly mixed in a mass ratio of approximately 3:7, and lithium hexafluorophosphate is added after mixing, and stirred until completely dissolved. Then, the electrolyte additive of the structural formula 1, vinylene carbonate, and fluoroethylene carbonate are added and mixed to obtain the electrolyte A1; wherein the molar concentration of lithium hexafluorophosphate is approximately 1.0 mol / L, the mass content of the structural formula 1 is approximately 1%, the mass content of vinylene carbonate is approximately 2%, and the mass content of fluoroethylene carbonate is approximately 1%.

[0085] (2)Battery

[0086] The positive electrode, negative electrode, separator and electrolyte A1 in step (1) were assembled into a 2Ah battery.

[0087] Example 2

[0088] (1) Electrolyte

[0089] Ethylene carbonate and dimethyl carbonate are uniformly mixed in a mass ratio of approximately 3:7, and after mixing, lithium bis(fluorosulfonyl)imide is added and stirred until completely dissolved. Then, the electrolyte additive of the structural formula 2, vinylene carbonate, and fluoroethylene carbonate are added and mixed to obtain the electrolyte A2; wherein the molar concentration of lithium bis(fluorosulfonyl)imide is approximately 2 mol / L, the mass content of the structural formula 2 is approximately 0.5%, the mass content of vinylene carbonate is approximately 2%, and the mass content of fluoroethylene carbonate is approximately 1%.

[0090] (2)Battery

[0091] The positive electrode, negative electrode, separator and electrolyte A2 in step (1) are assembled into a 2Ah battery.

[0092] Example 3

[0093] (1) Electrolyte

[0094] Ethylene carbonate and dimethyl carbonate are uniformly mixed in a mass ratio of approximately 3:7, and after mixing, lithium bis(fluorosulfonyl)imide is added and stirred until completely dissolved. Then, the electrolyte additive of the structural formula 3, vinylene carbonate, and fluoroethylene carbonate are added and mixed to obtain the electrolyte A3; wherein the molar concentration of lithium bis(fluorosulfonyl)imide is approximately 3 mol / L, the mass content of the structural formula 3 is approximately 1.5%, the mass content of vinylene carbonate is approximately 2%, and the mass content of fluoroethylene carbonate is approximately 1%.

[0095] (2)Battery

[0096] The positive electrode, negative electrode, separator and electrolyte A3 in step (1) were assembled into a 2Ah battery.

[0097] Example 4

[0098] (1) Electrolyte

[0099] Ethylene carbonate and dimethyl carbonate are uniformly mixed in a mass ratio of approximately 3:7, and after mixing, lithium bis(fluorosulfonyl)imide is added and stirred until completely dissolved. Then, the electrolyte additive of the structural formula 4, vinylene carbonate, and fluoroethylene carbonate are added and mixed to obtain the electrolyte A4; wherein the molar concentration of lithium bis(fluorosulfonyl)imide is approximately 1 mol / L, the mass content of the structural formula 4 is approximately 0.8%, the mass content of vinylene carbonate is approximately 2%, and the mass content of fluoroethylene carbonate is approximately 1%.

[0100] (2)Battery

[0101] The positive electrode, negative electrode, separator and electrolyte A4 in step (1) were assembled into a 2Ah battery.

[0102] Example 5

[0103] (1) Electrolyte

[0104] Ethylene carbonate and dimethyl carbonate are uniformly mixed in a mass ratio of approximately 3:7, and lithium hexafluorophosphate is added after mixing, and stirred until completely dissolved. Then, the electrolyte additive of the structural formula 5, vinylene carbonate, and fluoroethylene carbonate are added and mixed to obtain the electrolyte A5; wherein the molar concentration of lithium hexafluorophosphate is approximately 1 mol / L, the mass content of the structural formula 5 is approximately 0.8%, the mass content of vinylene carbonate is approximately 2%, and the mass content of fluoroethylene carbonate is approximately 1%.

[0105] (2)Battery

[0106] The positive electrode, negative electrode, separator and electrolyte A5 in step (1) were assembled into a 2Ah battery.

[0107] Example 6

[0108] (1) Electrolyte

[0109] Ethylene carbonate and dimethyl carbonate are uniformly mixed in a mass ratio of approximately 3:7, lithium hexafluorophosphate is added after mixing, and stirred until completely dissolved. Then, the electrolyte additive of the above-mentioned formula 6 and vinylene carbonate are added and mixed to obtain the electrolyte A6; wherein the molar concentration of lithium hexafluorophosphate is approximately 1.5 mol / L, the mass content of the formula 6 is approximately 1.3%, the mass content of vinylene carbonate is approximately 2%, and the mass content of fluoroethylene carbonate is approximately 1%.

[0110] (2)Battery

[0111] The positive electrode, negative electrode, separator and electrolyte A6 in step (1) were assembled into a 2Ah battery.

[0112] Example 7

[0113] An electrolyte and a battery were prepared according to the method of Example 1, with the only difference being that the mass content of the compound of Formula 1 in the electrolyte was about 0.5%. The prepared electrolyte was designated as A7.

[0114] Example 8

[0115] An electrolyte and a battery were prepared according to the method of Example 1, with the only difference being that the mass content of the compound of Formula 1 in the electrolyte was about 1.5%. The prepared electrolyte was designated as A8.

[0116] Example 9

[0117] An electrolyte and a battery were prepared according to the method of Example 1, except that the mass content of the compound of Formula 1 in the electrolyte was about 0.3%. The prepared electrolyte was designated as A9.

[0118] Example 10

[0119] An electrolyte and a battery were prepared according to the method of Example 1, except that the mass content of the compound of Formula 1 in the electrolyte was about 2%. The prepared electrolyte was denoted as A10.

[0120] Comparative Example 1

[0121] An electrolyte and a battery were prepared according to the method of Example 1, except that the compound of Formula 1 was not added to the electrolyte. The prepared electrolyte was recorded as B1.

[0122] Comparative Example 2

[0123] An electrolyte and a battery were prepared according to the method of Example 1, with the only difference being that the compound of Formula 1 in the electrolyte was replaced by vinyl sulfate, and the mass concentration of vinyl sulfate in the electrolyte was about 0.5%. The prepared electrolyte was recorded as B2.

[0124] Comparative Example 3

[0125] An electrolyte and a battery were prepared according to the method of Example 1, except that the compound of Formula 1 in the electrolyte was replaced by vinyl sulfate, and the mass concentration of vinyl sulfate in the electrolyte was about 1%. The prepared electrolyte was recorded as B3.

[0126] Comparative Example 4

[0127] An electrolyte and a battery were prepared according to the method of Example 1, except that the compound of Formula 1 in the electrolyte was replaced by vinyl sulfate, and the mass concentration of vinyl sulfate in the electrolyte was about 1.5%. The prepared electrolyte was recorded as B4.

[0128] Comparative Example 5

[0129] An electrolyte and a battery were prepared according to the method of Example 1, except that the compound of formula 1 in the electrolyte was replaced by methylene methanedisulfonate, and the mass concentration of vinyl sulfate in the electrolyte was about 0.5%. The prepared electrolyte was recorded as B5.

[0130] Comparative Example 6

[0131] An electrolyte and a battery were prepared according to the method of Example 1, except that the compound of formula 1 in the electrolyte was replaced by methylene methanedisulfonate, and the mass concentration of vinyl sulfate in the electrolyte was about 1%. The prepared electrolyte was recorded as B6.

[0132] Comparative Example 7

[0133] An electrolyte and a battery were prepared according to the method of Example 1, except that the compound of formula 1 in the electrolyte was replaced by methylene methanedisulfonate, and the mass concentration of vinyl sulfate in the electrolyte was about 1.5%. The prepared electrolyte was recorded as B7.

[0134] Comparative Example 8

[0135] An electrolyte and a battery were prepared according to the method of Example 1, except that the compound of Formula 1 in the electrolyte was replaced by 1,3,2,4-dioxadithiane 2,2,4,4-tetraoxide (CAS No.: 503-41-3), and the mass concentration of vinyl sulfate in the electrolyte was about 0.5%. The prepared electrolyte was recorded as B8.

[0136] Comparative Example 9

[0137] An electrolyte and a battery were prepared according to the method of Example 1, except that the compound of Formula 1 in the electrolyte was replaced by 1,3,2,4-dioxadithiane 2,2,4,4-tetraoxide (CAS No.: 503-41-3), and the mass concentration of vinyl sulfate in the electrolyte was approximately 1%. The prepared electrolyte was recorded as B9.

[0138] Comparative Example 10

[0139] An electrolyte and a battery were prepared according to the method of Example 1, except that the compound of Formula 1 in the electrolyte was replaced with 1,3,2,4-dioxadithiane 2,2,4,4-tetraoxide (CAS No.: 503-41-3), and the mass concentration of vinyl sulfate in the electrolyte was approximately 1.5%. The prepared electrolyte was recorded as B10.

[0140] The performance of the batteries prepared using the above A1-A10 and B1-B10 was tested, and the test method included:

[0141] Cycle performance test: The battery was charged and discharged at a rate of 1C in the voltage range of 2.5V to 3.65V. When charged to 3.65V, constant voltage charging was performed with a cut-off current of 0.05C. Cycle test was performed at a cycle temperature of 45°C to test the cycle capacity retention rate.

[0142] Charging storage test: The fully charged battery with 100% SOC was stored at 60°C, and the battery capacity remaining and capacity recovery were measured every 15 days. Then the battery was charged to 100% SOC and stored for 2 months.

[0143] The test results are shown in Table 1.

[0144] Table 1

[0145] From the table above we can see that:

[0146] (1) Comparing Example 1 with Examples 7 to 10, it can be seen that the present application controls the amount of electrolyte additives added, preferably 1%, thereby having the advantages of stable SEI film formation and low impedance.

[0147] (2) Compared with Comparative Examples 1 to 10, Example 1 shows that the electrolyte additive in the present application decomposes in the formation stage to participate in the SEI film formation of the negative electrode, inhibits the side reaction decomposition of the electrolyte organic solvent, and can form a more stable SEI passivation film with the negative electrode. Moreover, during the battery cycle and storage process, the interface stability can be improved to inhibit the irreversible consumption of capacity caused by the side reaction decomposition of the electrolyte, significantly inhibit the gas production of the electrolyte side reaction during the battery charge and discharge process and reduce the impedance, thereby improving the high-temperature cycle and storage performance of the battery.

[0148] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0149] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the inventive concept of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An electrolyte additive for a battery, wherein: The electrolyte additive comprises a sulfate ester compound, and the chemical formula of the sulfate ester compound is: Wherein, R1 is selected from a halogen atom, and R2, R3 and R4 are independently selected from one or more of a hydrogen atom, a halogen atom, a C1-C6 alkyl group or a C1-C6 fluoroalkyl group.

2. The electrolyte additive according to claim 1, wherein In the chemical formula of the sulfate ester compound, R1 is a fluorine atom.

3. The electrolyte additive according to claim 1 or 2, wherein The sulfate compounds include: At least one of .

4. An electrolyte, wherein The electrolyte comprises a lithium salt, a solvent and an additive, and the additive comprises the electrolyte additive for a battery according to any one of claims 1 to 3.

5. The electrolyte according to claim 4, wherein The mass content of the electrolyte additive for the battery in the electrolyte is about 0.5% to about 1.5%.

6. The electrolyte according to claim 4 or 5, wherein The molar concentration of the lithium salt in the electrolyte is about 0.5 mol / L to about 3 mol / L.

7. The electrolyte according to any one of claims 4 to 6, wherein The lithium salt includes at least one of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide.

8. The electrolyte according to any one of claims 4 to 7, wherein The solvent includes at least one of propylene carbonate, ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, butylene carbonate, methylpropyl carbonate, dioxolane, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, methyl acetate, ethyl acetate, dimethyl sulfoxide and sulfolane.

9. The electrolyte according to any one of claims 4 to 8, wherein The additives also include functional additives.

10. The electrolyte according to claim 9, wherein The functional additive includes at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propane sultone, 1,3-propylene sultone, lithium difluorophosphate and lithium difluorooxalatoborate.

11. The electrolyte according to claim 9 or 10, wherein The mass content of the functional additive in the electrolyte is 0.1% to 2%.

12. A battery, wherein: The battery comprises a positive electrode, a negative electrode, a separator and the electrolyte according to any one of claims 4 to 11.

13. The battery according to claim 12, wherein The battery is a lithium-ion battery.

14. A battery module, wherein: The battery module comprises: a plurality of batteries connected in series and / or in parallel, wherein at least one battery is the battery according to any one of claims 12 to 13.

15. An electrical device, wherein: The electrical device comprises: a battery module as claimed in claim 14 or a single battery as claimed in any one of claims 12 to 13.

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