CN116706232A - Electrolyte of secondary battery, secondary battery and electronic device - Google Patents

Electrolyte of secondary battery, secondary battery and electronic device Download PDF

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Publication number
CN116706232A
CN116706232A CN202310744959.5A CN202310744959A CN116706232A CN 116706232 A CN116706232 A CN 116706232A CN 202310744959 A CN202310744959 A CN 202310744959A CN 116706232 A CN116706232 A CN 116706232A
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electrolyte
secondary battery
compound
mass
performance
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简俊华
刘建禹
郭和峰
唐超
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Ningde Amperex Technology Ltd
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Ningde Amperex Technology Ltd
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Priority to CN202310744959.5A priority Critical patent/CN116706232A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Secondary Cells (AREA)

Abstract

The application provides an electrolyte of a secondary battery, the secondary battery and an electronic device. Wherein the electrolyte comprises electrolyte salt, non-aqueous organic solvent and compound shown in formula (I), and the mass percentage of the compound shown in formula (I) is x% which is more than or equal to 0.01 and less than or equal to 10 based on the mass of the electrolyte. The electrolyte comprises a compound shown in a formula (I) and the mass percentage content of the compound is regulated and controlled to be within the range of the application, the compound shown in the formula (I) reacts with the anode active material to generate an interface protection layer containing tin, so that the reactivity of the anode active material can be reduced, the problems that the electrolyte is excessively consumed and the secondary battery generates gas at high temperature are solved, and the cycle performance, the high-temperature storage performance and the kinetic performance of the secondary battery are improved.

Description

Electrolyte of secondary battery, secondary battery and electronic device
Technical Field
The present application relates to the field of electrochemical technology, and in particular, to an electrolyte for a secondary battery, and an electronic device.
Background
Secondary batteries, such as lithium ion batteries, are widely used in mobile phones, notebook computers, tablet computers, unmanned aerial vehicles, electric tools, power storage systems, and the like because of their advantages such as high energy density, miniaturization, and weight reduction.
In the face of increasing energy density rise demands, lithium ion batteries are in need of using electrode materials having higher specific capacities. Alloy anode materials such as silicon-based materials have been attracting attention as a technique having great potential therein, however alloy anodes tend to have high reactivity in a state of highly intercalating lithium, which brings about adverse effects. For example, the electrolyte is easy to react with the electrolyte in the circulating process, so that the electrolyte is excessively consumed, and the circulating performance of the lithium ion battery is affected.
Disclosure of Invention
The application aims to provide an electrolyte of a secondary battery, the secondary battery and an electronic device, so as to improve the cycle performance of the secondary battery. The specific technical scheme is as follows:
the first aspect of the present application provides an electrolyte for a secondary battery, comprising an electrolyte salt, a nonaqueous organic solvent, and a compound represented by formula (I);
wherein R is 1 To R 4 Each independently selected from C 1 -C 8 Alkyl, C 3 -C 8 Cycloalkyl, C 2 -C 8 Alkenyl, phenyl, phenoxy, C 2 -C 10 Alkyl, C containing ether linkage 1 -C 10 Alkoxy or C 2 -C 10 An acyloxy group; r is R 1 To R 4 At least one of them is selected from oxygen-containing groups, R 1 To R 4 Can be linked to form a ring; the mass percentage of the compound represented by the formula (I) is x%, 0.01.ltoreq.x.ltoreq.10, preferably 0.1.ltoreq.x.ltoreq.5, based on the mass of the electrolyte, for example, the mass percentage x% of the compound represented by the formula (I) may be 0.01%, 0.05%, 0.08%, 0.1%, 0.5%, 0.8%, 1%, 2%, 3%, 4%, 5%, 6%, 8%, 9%, 10% or a range of any two values thereof.
The electrolyte comprises a compound shown in a formula (I) and the mass percentage content of the compound is regulated and controlled within the range of the application, and the compound shown in the formula (I) reacts with the anode active material at the interface in the first charging process of the secondary battery to generate an interface protection layer containing tin, so that the reactivity of the anode can be reduced, the problems that the electrolyte is excessively consumed and the secondary battery generates gas at high temperature are solved, and the cycle performance and the high-temperature storage performance of the secondary battery are improved. And oxygen-containing groups in the compound shown in the formula (I) can be decomposed in the formation and circulation processes of the secondary battery, and the decomposition products have high ion conductivity, so that the transmission rate of ions at the interface can be improved, and the kinetic performance of the secondary battery is improved. When x is too small, for example, less than 0.01, the content of the compound represented by the formula (I) is too small, a complete interface protection layer containing tin cannot be formed on the surface of the negative electrode, the reactivity of the negative electrode cannot be reduced, and the problems that the electrolyte is excessively consumed and the secondary battery generates gas at high temperature cannot be solved, which is unfavorable for improving the cycle performance, the high-temperature storage performance and the kinetic performance of the secondary battery. When x is too large, for example, greater than 10, the viscosity of the electrolyte is too large, which is not beneficial to the diffusion and transmission of ions in the electrolyte, and the compound shown in formula (I) is caused to participate in the interface reaction in a transitional manner, so that the thickness of the tin-containing interface protection layer formed on the surface of the anode is too large, which is not beneficial to the improvement of the cycle performance of the secondary battery. The regulation and control of x in the range of the application is beneficial to forming the interface protection layer with proper thickness and containing tin on the surface of the anode, and can improve the cycle performance, high-temperature storage performance and dynamic performance of the secondary battery. In the present application, "high temperature" means a temperature of 60 ℃ or higher, and normal temperature means a temperature of 25 ℃ + -5 ℃.
In the present application, the above-mentioned "R 1 To R 4 Wherein adjacent two groups can be linked to form a ring "means R 1 To R 4 Two adjacent groups are connected through single bond to form five-membered heterocycle, six-membered heterocycle, seven-membered heterocycle or eight-membered heterocycle containing hetero atoms O and Sn. In some embodiments, R as described above 1 To R 4 The adjacent two groups of the two groups can be connected to form the heterocyclic structure. In other embodimentsIn the scheme, R is as follows 1 To R 4 The adjacent two groups of (a) may not be connected to form a ring.
In some embodiments of the application, the compound of formula (I) comprises at least one of the following compounds:
the electrolyte comprising the compound shown in the formula (I) in the range is applied to the secondary battery, and the compound shown in the formula (I) reacts with the negative electrode active material at the interface of the negative electrode plate and the electrolyte in the first charging process of the secondary battery to generate an interface protection layer containing tin, so that the reactivity of the negative electrode active material can be reduced, the problems that the electrolyte is excessively consumed and the secondary battery generates gas at high temperature are solved, and the cycle performance and the high-temperature storage performance of the secondary battery are improved. In addition, the oxygen-containing group in the compound shown in the formula (I) can be decomposed in the cycle process of the secondary battery, and the decomposition product has high ionic conductivity, so that the transmission rate of ions at the interface can be improved, and the kinetic performance of the secondary battery is improved.
In some embodiments of the application, the electrolyte further comprises a dinitrile compound comprising at least one of succinonitrile, glutaronitrile, methylglutaronitrile, adiponitrile, pimelic nitrile, suberonitrile, nonyldinitrile, or decyldinitrile; the mass percent of dinitriles is 0.5% to 5% based on the mass of the electrolyte, e.g., the mass percent of dinitriles may be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 5% or a range of any two values therein. The electrolyte comprises the dinitrile compound in the range, and the content of the dinitrile compound is regulated and controlled in the range, so that the stability of the interface protective layer containing tin can be improved, the reactivity of the anode active material is further reduced, the problems that the electrolyte is excessively consumed and the secondary battery generates gas at high temperature are solved, and the cycle performance and the high-temperature storage performance of the secondary battery are further improved.
In some embodiments of the application, the electrolyte further comprises a fluorocarbonate, the fluorocarbonate comprising at least one of fluoroethylene carbonate, bis-fluoroethylene carbonate, trifluoromethyl ethylene carbonate, methyldifluoroethyl carbonate, methyltrifluoroethyl carbonate, ethyltrifluoroethyl carbonate, methylhexafluoroisopropyl carbonate, or bis (2, 2-trifluoroethyl) carbonate. Based on the mass of the electrolyte, the mass percentage of the fluorocarbonate is y.ltoreq.y.ltoreq.50, preferably 5.ltoreq.y.ltoreq.40. For example, the mass percent y% of the fluorocarbonate may be 1%, 3%, 5%, 10%, 20%, 25%, 30%, 40%, 50% or a range of any two values therein. In the present application, the fluorocarbonate may be used as a solvent or an additive, and the present application is not particularly limited as long as the object of the present application can be achieved. The electrolyte comprises the fluorocarbonate, so that a proper amount of lithium fluoride can be introduced into the interface protective layer, an effect of well passivating an interface layer between the negative electrode plate and the electrolyte is achieved, and the reaction between the negative electrode plate and the electrolyte is reduced, so that the problem that the electrolyte is excessively consumed is solved, the cycle performance of the secondary battery is improved, but the fluorocarbonate is easy to decompose at high temperature to generate HF, the viscosity of the electrolyte is increased, and the high-temperature storage performance and the dynamic performance are not facilitated. The electrolyte contains the compound shown in the formula (I) and further introduces the fluorocarbonate in the range, and the content of the fluorocarbonate is regulated and controlled in the range, so that the problem that the electrolyte is excessively consumed can be solved, the problem of high-temperature gas production of the secondary battery can be solved, and the transfer of ions in the interface layer can be facilitated, so that the secondary battery has better high-temperature storage performance and dynamic performance and better cycle performance.
In some embodiments of the application, 0.005.ltoreq.x/y.ltoreq.1, e.g., the value of x/y may be 0.005, 0.008, 0.01, 0.03, 0.05, 0.08, 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, 0.8, 1 or a range of any two values therein. By regulating x/y within the above range, the synergistic effect of the compound shown in the formula (I) and the fluorocarbonate is brought into play, the problem of gas production can be improved while the stability of the interface between the negative electrode plate and the electrolyte is enhanced, and the ion transmission rate in the interface is improved, so that the secondary battery has good high-temperature storage performance and dynamic performance and better cycle performance, and the gas production problem at high temperature and the gas production problem in the cycle process can be improved, thereby being beneficial to improving the use safety of the secondary battery.
In some embodiments of the application, the electrolyte further comprises a carboxylate compound. The carboxylic ester compound comprises C 3 -C 10 Carboxylic acid esters or C 3 -C 10 At least one of the halogenated carboxylic acid esters of (a). The mass percentage of the carboxylate compound is 1% to 80%, preferably 10% to 60%, based on the mass of the electrolyte. For example, the mass percent of the carboxylate compound may be 1%, 3%, 5%, 10%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 75%, 80% or a range of any two values therein. The electrolyte comprises a compound shown in a formula (I) and further introduces carboxylate compounds in the range, which is favorable for improving the stability of an interface protection layer containing tin, further reducing the reactivity of a cathode active material, thereby improving the problems that the electrolyte is excessively consumed and the secondary battery generates gas at high temperature, reducing the viscosity of the electrolyte, simultaneously, the carboxylate compounds have smaller ion (such as lithium ion or sodium ion) binding energy, so that the electrolyte salt has higher solubility, the transmission capability of ions in the electrolyte is favorable for improving, on one hand, concentration polarization is reduced, on the other hand, the interface protection layer containing tin is favorable for embedding the ions, the uniformity and the rate of ion embedding of the cathode electrode plate can be improved, and the lithium/sodium precipitation risk of the cathode electrode plate is reduced, thereby enabling secondary electrodes The pool has good high-temperature storage performance and dynamic performance, and better cycle performance and safety performance.
In some embodiments of the present application, the carboxylic ester compound comprises beta-propiolactone, gamma-butyrolactone, delta-valerolactone, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl tert-butyrate at least one of 2, 2-difluoroethyl acetate, 2-trifluoroethyl acetate, hexafluoroisopropyl acetate, 2-difluoroethyl propionate, 2-trifluoroethyl propionate or hexafluoroisopropyl propionate. The electrolyte comprises the carboxylate compound in the range, which is beneficial to reducing the viscosity of the electrolyte, and meanwhile, the carboxylate compound has smaller ion (such as lithium ion or sodium ion) binding energy, which is beneficial to improving the ion transmission capacity in the electrolyte, thereby further improving the dynamic performance of the secondary battery.
In the present application, the electrolyte salt may include, but is not limited to, lithium salt or sodium salt, and the lithium salt may include, but is not limited to, at least one of lithium hexafluorophosphate, lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethylsulfonyl) borate, lithium difluorooxalato borate, lithium difluorophosphate, lithium tetrafluoroborate, lithium nitrate, lithium hexafluoroantimonate, lithium hexafluoroarsenate, lithium bis (trifluoromethylsulfonyl) imide, lithium bis (pentafluoroethylsulfonyl) imide, lithium tris (trifluoromethylsulfonyl) methyl lithium, lithium difluorooxalato phosphate, or lithium tetrafluorooxalato phosphate; the sodium salt may include, but is not limited to, at least one of sodium hexafluorophosphate, sodium perchlorate, sodium trifluoromethylsulfonate, sodium tetrachloroaluminate, sodium tetrachloroborate, sodium tetrafluoroborate, sodium nitrate, sodium tetrafluorophosphate, sodium hexafluoroarsenate, or sodium hexafluoroantimonate. The present application is not particularly limited as long as the object of the present application can be achieved. Illustratively, the above-mentioned electrolyte salt is 8 to 23% by mass based on the mass of the electrolyte, for example, the electrolyte salt may be 8%, 9%, 10%, 12%, 13%, 15%, 17%, 19%, 21%, 23% by mass or a range of any two values therein.
In the present application, the non-aqueous organic solvent may include, but is not limited to, non-fluorinated carbonates, which may include at least one of ethylene carbonate, propylene carbonate, butylene carbonate, hexene carbonate, octene carbonate, dimethyl carbonate, methylethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, dioctyl carbonate, dipentyl carbonate, ethylisobutyl carbonate, isopropyl methyl carbonate, di-n-butyl carbonate, diisopropyl carbonate, or propyl carbonate. The present application is not particularly limited as long as the object of the present application can be achieved. Illustratively, the non-fluorinated carbonate may be present in an amount of 1.5% to 91% by mass, based on the mass of the electrolyte, and the non-fluorinated carbonate may be present in an amount of 1.5%, 3%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 89%, 91% by mass, or in a range of any two values therein.
In some embodiments of the application, the electrolyte comprises a compound of formula (I), an electrolyte salt, and a non-fluorinated carbonate; the mass percentage of the compound represented by the formula (I) and the electrolyte salt is 67 to 91% based on the mass of the electrolyte solution as described above. The application of the electrolyte having the above characteristics to a secondary battery can provide the secondary battery with good cycle performance, high-temperature storage performance and dynamic performance.
In some embodiments of the present application, the electrolyte comprises a compound represented by formula (I), an electrolyte salt, and a non-fluorinated carbonate, and optionally, the electrolyte further comprises at least one of a dinitrile compound, a fluorinated carbonate, and a carboxylate compound. In some embodiments, the electrolyte includes a compound of formula (I), a dinitrile compound, an electrolyte salt, and a non-fluorinated carbonate; the mass percentage of the compound represented by the formula (I), the dinitrile compound, the electrolyte salt and the non-fluorinated carbonate is as described above, and the mass percentage of the non-fluorinated carbonate is 62% to 91% based on the mass of the electrolyte. The electrolyte with the characteristics is applied to the secondary battery, which is beneficial to further improving the cycle performance, the high-temperature storage performance and the dynamic performance of the secondary battery.
In some embodiments, the electrolyte includes a compound of formula (I), an electrolyte salt, a fluorocarbonate, and a non-fluorocarbonate. The mass percentage of the compound represented by the formula (I), the electrolyte salt and the fluorocarbonate is as described above, and the mass percentage of the non-fluorocarbonate is 30% to 90% based on the mass of the electrolyte. The application of the electrolyte having the above characteristics to a secondary battery can allow the secondary battery to have good high-temperature storage performance and dynamic performance while further improving its cycle performance.
In some embodiments, the electrolyte includes a compound of formula (I), an electrolyte salt, a fluorocarbonate, and a carboxylate compound; the mass percentage of the compound represented by the formula (I), the electrolyte salt, the fluorocarbonate and the carboxylate compound is as described above, and the mass percentage of the non-fluorocarbonate is 1.5% to 85% based on the mass of the electrolyte. The application of the electrolyte with the characteristics to the secondary battery can enable the secondary battery to have good high-temperature storage performance and further improve the cycle performance, the dynamic performance and the safety performance.
In some embodiments, the electrolyte includes a compound of formula (I), a dinitrile compound, an electrolyte salt, a fluorocarbonate, a carboxylate compound, and a non-fluorocarbonate. The mass percentage of the compound represented by the formula (I), the dinitrile compound, the electrolyte salt, the fluorocarbonate and the carboxylate compound is as described above, and the mass percentage of the non-fluorocarbonate is 1.5% to 89% based on the mass of the electrolyte. The electrolyte with the characteristics is applied to the secondary battery, and is more beneficial to improving the cycle performance, the high-temperature storage performance and the dynamic performance of the secondary battery.
A second aspect of the present application provides a secondary battery comprising a positive electrode tab, a negative electrode tab, and the electrolyte provided in the first aspect of the present application. The secondary battery provided in the second aspect of the present application has good cycle performance, high-temperature storage performance and dynamic performance.
In some embodiments of the present application, the negative electrode tab includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, the negative electrode active material layer including a negative electrode active material, the negative electrode active material including a silicon-based material. The negative electrode active material in the above range is selected, and the negative electrode active material has a high specific capacity, so that the secondary battery has good cycle performance, high-temperature storage performance and dynamic performance, and also has high energy density.
The present application is not particularly limited as long as the object of the present application can be achieved. For example, the silicon-based material may include, but is not limited to, those containing LiF, alF 3 、Li 2 CO 3 Silicon nanoparticles, silicon nanowires, microsilica, silicon oxide materials (SiO) of coating layers of amorphous carbon, graphitized carbon or organic polymers w 0 < w.ltoreq.2), silicon-carbon composite materials (SiC) or silicon-based alloy materials, the silicon-based alloy materials can include but are not limited to silicon-tin alloys, silicon-magnesium alloys, silicon-aluminum alloys, silicon-iron alloys, and the like, and the organic polymers can include but are not limited to polyaniline, polypyrrole, poly (3, 4-ethylenedioxythiophene), polyacrylate, polyacrylic acid, polymaleic acid, and the like. The negative electrode active material of the present application may further include natural graphite, artificial graphite, intermediate phase micro carbon spheres (MCMB), hard carbon, soft carbon, li-Sn alloy, li-Sn-O alloy, sn, snO, snO 2 Spinel-structured lithium titanate Li 4 Ti 5 O 12 At least one of Li-Al alloy, metallic lithium, and the like.
The thicknesses of the anode current collector and the anode active material layer are not particularly limited as long as the object of the present application can be achieved. For example, the negative electrode current collector has a thickness of 4 μm to 16 μm, and the single-sided negative electrode active material layer has a thickness of 30 μm to 130 μm. In the present application, the anode active material layer may be provided on one surface in the anode current collector thickness direction, or may be provided on both surfaces in the anode current collector thickness direction. The "surface" here may be the entire region of the negative electrode current collector or may be a partial region of the negative electrode current collector, and the present application is not particularly limited as long as the object of the present application can be achieved. The anode active material layer of the present application may further contain a conductive agent and a binder. Optionally, the negative electrode tab of the present application may further include a conductive layer, which may be disposed between the negative electrode current collector and the negative electrode active material layer, and the conductive layer may be disposed on one surface in the thickness direction of the negative electrode current collector or may be disposed on both surfaces in the thickness direction of the negative electrode current collector. The composition of the conductive layer is not particularly limited in the present application, and may include a conductive agent and a binder.
The positive electrode sheet of the present application is not particularly limited as long as the object of the present application can be achieved. For example, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector. The positive electrode current collector is not particularly limited as long as the object of the present application can be achieved. For example, the positive electrode current collector may include an aluminum foil or an aluminum alloy foil, or the like. The positive electrode active material layer of the present application contains a positive electrode active material. The kind of the positive electrode active material is not particularly limited as long as the object of the present application can be achieved. For example, the positive electrode active material may contain nickel cobalt lithium manganate (NCM 811, NCM622, NCM523, NCM 111), nickel cobalt lithium aluminate, lithium iron phosphate, lithium-rich manganese-based material, lithium cobaltate (LiCoO) 2 ) At least one of lithium manganate, lithium iron manganese phosphate, lithium titanate, and the like. In the present application, the positive electrode active material may further contain a non-metal element, for example, at least one of fluorine, phosphorus, boron, chlorine, silicon, sulfur, etc., which further improves the stability of the positive electrode active material. In the present application, the thicknesses of the positive electrode current collector and the positive electrode active material layer are not particularly limited as long as the object of the present application can be achieved. For example, the thickness of the positive electrode current collector is 5 μm to 20 μm, preferably 6 μm to 18 μm. The thickness of the single-sided positive electrode active material layer is 30 μm to 120 μm. In the present application, the positive electrode active material layer may be provided on one surface in the thickness direction of the positive electrode current collector, or may be provided on both surfaces in the thickness direction of the positive electrode current collector. The "surface" here may be the entire region of the positive electrode current collector or may be a partial region of the positive electrode current collector, and the present application is not particularly limited as long as the object of the present application can be achieved. The positive electrode of the application The active material layer may further include a conductive agent and a binder. Optionally, the positive electrode tab may further include a conductive layer located between the positive electrode current collector and the positive electrode active material layer.
The above-mentioned conductive agent and binder are not particularly limited as long as the object of the present application can be achieved. For example, the conductive agent may include at least one of conductive carbon black (Super P), carbon Nanotubes (CNTs), carbon nanofibers, crystalline flake graphite, graphene, or the like. The binder may include at least one of polyacrylate, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyamideimide, styrene Butadiene Rubber (SBR), polyvinyl alcohol (PVA), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), aqueous acrylic resin, carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (CMC-Na), or the like.
The secondary battery of the present application further includes a separator, and the present application is not particularly limited as long as the object of the present application can be achieved. For example, the release film may include a substrate layer and a surface treatment layer. The substrate layer may be a nonwoven fabric, a film, or a composite film having a porous structure, and the material of the substrate layer may include at least one of polyethylene, polypropylene, polyethylene terephthalate, polyimide, or the like. Optionally, a polypropylene porous membrane, a polyethylene porous membrane, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite membrane may be used. Optionally, a surface treatment layer is disposed on at least one surface of the substrate layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or may be a layer formed by mixing a polymer and an inorganic material. For example, the inorganic layer includes inorganic particles and a binder, and the inorganic particles are not particularly limited, and may be selected from at least one of alumina, silica, magnesia, titania, hafnia, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide, zirconia, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, barium sulfate, and the like, for example. The binder is not particularly limited, and may be, for example, at least one selected from polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene, polyhexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyvinylpyrrolidone, polyvinyl ether, and polymethyl methacrylate. The polymer layer contains polymer, and the material of the polymer comprises at least one of polyamide, polyacrylonitrile, acrylic polymer, polyacrylic acid, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or polyvinylidene fluoride-hexafluoropropylene and the like. In the present application, the thickness of the separator is not particularly limited as long as the object of the present application can be achieved, for example, the thickness of the separator may be 5 μm to 500 μm.
The secondary battery of the present application is not particularly limited, and may include any device in which an electrochemical reaction occurs. In one embodiment of the present application, the secondary battery may include, but is not limited to: lithium ion batteries, lithium metal batteries, sodium ion batteries, sodium metal batteries, sodium polymer batteries, sodium ion polymer batteries, lithium ion polymer batteries, and the like.
The process of manufacturing the secondary battery is well known to those skilled in the art, and the present application is not particularly limited, and may include, for example, but not limited to, the following steps: sequentially stacking the positive electrode plate, the isolating film and the negative electrode plate, winding and folding the positive electrode plate, the isolating film and the negative electrode plate according to the requirement to obtain an electrode assembly with a winding structure, placing the electrode assembly into a packaging bag, injecting electrolyte into the packaging bag, and sealing to obtain a secondary battery; or sequentially stacking the positive electrode plate, the isolating film and the negative electrode plate, fixing four corners of the whole lamination structure by using adhesive tapes to obtain an electrode assembly of the lamination structure, placing the electrode assembly into a packaging bag, injecting electrolyte into the packaging bag and sealing to obtain the secondary battery. In addition, an overcurrent prevention element, a guide plate, or the like may be placed in the package bag as needed, thereby preventing the pressure inside the secondary battery from rising and overcharging and discharging. The present application is not limited to the packaging bag, and those skilled in the art can select according to actual needs, as long as the objects of the present application can be achieved. For example, an aluminum plastic film package may be used.
A third aspect of the application provides an electronic device comprising the secondary battery provided in the second aspect of the application. The secondary battery provided in the second aspect of the present application has good high-temperature storage performance, cycle performance and kinetic performance. Thus, the electronic device has longer service life.
The electronic device of the present application is not particularly limited, and may be any electronic device known in the art. In some embodiments, the electronic device may include, but is not limited to, a notebook computer, a pen-input computer, a mobile computer, an electronic book player, a portable telephone, a portable facsimile machine, a portable copier, a portable printer, a headset, a video recorder, a liquid crystal television, a portable cleaner, a portable CD-player, a mini-compact disc, a transceiver, an electronic organizer, a calculator, a memory card, a portable audio recorder, a radio, a backup power source, a motor, an automobile, a motorcycle, a power assisted bicycle, a lighting fixture, a toy, a game machine, a clock, an electric tool, a flash light, a camera, a household large battery or a lithium ion capacitor, and the like.
The application has the beneficial effects that:
The application provides an electrolyte of a secondary battery, the secondary battery and an electronic device. Wherein the electrolyte comprises electrolyte salt, non-aqueous organic solvent and compound shown in formula (I), and the mass percentage of the compound shown in formula (I) is x% which is more than or equal to 0.01 and less than or equal to 10 based on the mass of the electrolyte. The electrolyte comprises a compound shown in a formula (I) and the mass percentage content of the compound is regulated and controlled within the range of the application, and the compound shown in the formula (I) reacts with the negative electrode active material at the interface of the negative electrode plate and the electrolyte in the charging process of the secondary battery to generate an interface protection layer containing tin, so that the reactivity of the negative electrode plate can be reduced, the problems that the electrolyte is excessively consumed and the secondary battery generates gas at high temperature are solved, and the cycle performance and the high-temperature storage performance of the secondary battery are improved. The oxygen-containing group in the compound shown in the formula (I) can be decomposed in the cycle process of the secondary battery, and the decomposition product has high ion conductivity, so that the transmission rate of ions at an interface can be improved, and the kinetic performance of the secondary battery is improved.
Of course, it is not necessary for any one product or method of practicing the application to achieve all of the advantages set forth above at the same time.
Detailed Description
The following description of the technical solutions in the embodiments of the present application will be clear and complete, and it is obvious that the described embodiments are only some embodiments of the present application, but not all embodiments. Based on the embodiments of the present application, all other embodiments obtained by the person skilled in the art based on the present application are included in the scope of protection of the present application.
In the specific embodiment of the present application, the present application is explained using a lithium ion battery as an example of a secondary battery, but the secondary battery of the present application is not limited to a lithium ion battery.
Examples
Hereinafter, embodiments of the present application will be described in more detail with reference to examples and comparative examples. The various tests and evaluations were carried out according to the following methods. Unless otherwise specified, "parts" and "%" are mass references.
Test method and apparatus:
and (3) testing the cycle performance:
and placing the lithium ion battery in a constant temperature test box at 25 ℃, and standing for 30 minutes to enable the lithium ion battery to reach constant temperature. Charging to 4.5V with constant current of 0.5C, charging to current of 0.025C with constant voltage, standing for 5 min, discharging to 3.0V with constant current of 0.5C, and recording as initial discharge capacity C 0 . With this step, 100 cycles were repeated, and the discharge capacity C after 100 cycles was recorded 1 And calculating the cycle capacity retention rate of the lithium ion battery. Circulation capacity retention = C 1 /C 0 ×100％。
High temperature storage performance test:
and placing the lithium ion battery in a constant temperature environment at 25 ℃, and standing for 30 minutes to enable the lithium ion battery to reach constant temperature. The thickness of the lithium ion battery was recorded as the initial thickness by constant current charging to 4.5V at 0.5C and then constant voltage charging to 0.025C. The lithium ion battery was transferred to a 60 ℃ incubator for 30 days to store, during which the lithium ion battery thickness was tested and recorded once every 6 days, and the test thickness after 30 days was recorded as the storage thickness. And calculating the thickness expansion rate of the lithium ion battery and taking the thickness expansion rate as an index for evaluating the high-temperature storage performance of the lithium ion battery. High temperature storage expansion ratio= (storage thickness-initial thickness)/initial thickness×100%.
And (3) multiplying power performance test:
placing the lithium ion battery in a constant temperature box at 25 ℃, placing for 120 minutes, charging to 4.5V at constant current of 0.5C, charging to 0.025C at constant voltage, standing for 5 minutes, discharging to 3V at 0.2C, and recording discharge capacity C of 0.5C 2 Standing for 5 minutes. Charging to 4.5V again with constant current of 0.5C, charging to 0.025C again with constant voltage, standing for 5 min, discharging to 3V with 2C, and recording 2C discharge capacity C 3 .2C discharge capacity retention rate=c 3 /C 2 X 100%. The higher the 2C discharge capacity retention rate, the better the rate capability of the lithium ion battery, i.e. the better the dynamic performance.
Lithium precipitation test:
the lithium ion battery was placed in a 12 ℃ incubator for 120 minutes, charged to 4.5V at a constant current of 2C, charged to 0.025C at a constant voltage, left for 5 minutes, discharged to 3V at 0.5C, left for 60 minutes, which is one cycle. After 10 cycles are carried out, the lithium ion battery is disassembled after the constant-current charge of 2C is carried out to 4.5V and the constant-voltage charge is carried out to 0.025C, the lithium precipitation state of the surface of the negative electrode plate is observed, the lithium precipitation area on the surface of the negative electrode plate is golden yellow, and the lithium precipitation area is grey.
The judgment standard of the lithium precipitation degree of the lithium ion battery is as follows: the lithium-separating area is less than 2% and is not lithium-separating, the lithium-separating area is 2% to 10% and is slightly lithium-separating, the lithium-separating area is 10% to 30% and is moderately lithium-separating, the lithium-separating area is more than 30% and is severely lithium-separating, wherein the percentage of the lithium-separating area is calculated based on the total area of the negative electrode plate.
Example 1-1
< preparation of electrolyte >
In an argon atmosphere glove box with a water content of < 10ppm, mixing non-aqueous organic solvents of non-fluorocarbonate Ethylene Carbonate (EC) and dipropyl carbonate (DPC) according to a mass ratio of 3:7, then Then adding lithium hexafluorophosphate (LiPF) as lithium salt into the non-aqueous organic solvent 6 ) Dissolving and mixing uniformly, adding a compound shown in the formula (I) as formula (I-1), and stirring uniformly to obtain the electrolyte. Wherein, based on the mass of the electrolyte, the lithium salt LiPF 6 The mass percentage of the compound shown in the formula (I) is 12.5 percent, the mass percentage x% of the compound shown in the formula (I) is 1 percent, and the rest is non-aqueous organic solvent.
< preparation of Positive electrode sheet >
Lithium cobalt oxide (LiCoO) as a positive electrode active material 2 ) Mixing conductive carbon black (Super P) serving as a conductive agent and polyvinylidene fluoride (PVDF) serving as a binder according to a mass ratio of 97:1.4:1.6, adding N-methylpyrrolidone (NMP) serving as a solvent, preparing into slurry with a solid content of 75wt%, and stirring the slurry into uniform positive electrode slurry under the action of a vacuum stirrer. The positive electrode slurry was uniformly coated on one surface of a positive electrode current collector aluminum foil having a thickness of 10 μm, and dried at 85 deg.c to obtain a positive electrode of a single-sided coated positive electrode active material having a positive electrode active material layer thickness of 110 μm. And repeating the steps on the other surface of the positive electrode to obtain the positive electrode with the double-sided coating of the positive electrode active material. After the coating is completed, the positive electrode is cold-pressed and cut into a specification of 74mm multiplied by 867mm for standby.
< preparation of negative electrode sheet >
The preparation method comprises the steps of mixing negative active materials of artificial graphite, silicon/carbon composite materials (SiC), a conductive agent Super P, a thickener of sodium carboxymethylcellulose (CMC-Na), a binder of styrene-butadiene rubber (SBR) and lithium Polyacrylate (PAALi) according to a mass ratio of 67:25:1.5:0.5:1:5, adding deionized water as a solvent, preparing into negative electrode slurry with a solid content of 54wt%, and stirring under the action of a vacuum stirrer until the system becomes uniform negative electrode slurry. Mixing the conductive agent Super P and the binder SBR according to the mass ratio of 9:1, and then adding deionized water as a solvent to prepare the conductive layer slurry with the solid content of 10 wt%. The conductive layer slurry and the negative electrode slurry are sequentially and uniformly coated on one surface of a negative electrode current collector copper foil with the thickness of 12 mu m, and are dried at the temperature of 85 ℃ to obtain a single-sided coated negative electrode with the conductive layer thickness of 2 mu m and the negative electrode active material layer thickness of 100 mu m. And repeating the steps on the other surface of the negative electrode to obtain the double-sided coated negative electrode. After the coating is completed, the negative electrode is cold-pressed and cut into a specification of 76mm×851mm for standby.
< separation Membrane >
Polyethylene (PE) porous film (supplied by Celgard corporation) having a thickness of 5 μm was used.
< preparation of lithium ion Battery >
And sequentially stacking the prepared positive pole piece, the isolating film and the negative pole piece, so that the isolating film is positioned between the positive pole piece and the negative pole piece to play a role in isolation, and then winding to obtain the electrode assembly. After welding the electrode lugs, placing the electrode assembly into an aluminum plastic film packaging shell, drying the aluminum plastic film packaging shell in a vacuum oven at 85 ℃ for 12 hours to remove water, injecting the prepared electrolyte, and performing vacuum packaging, standing, formation (the temperature is 60 ℃, the constant current is charged to 3.5V at 0.02 ℃, the constant current is charged to 3.9V at 0.1 ℃), shaping, capacity testing and other procedures to obtain the lithium ion battery.
Examples 1-2 to 1-42
The procedure of example 1-1 was repeated except that the type and mass percentage of the compound represented by the formula (I) and the mass percentage of the nonaqueous organic solvent were changed as shown in Table 1 in < preparation of electrolyte >, and the mass percentage of the lithium salt was not changed.
Examples 2-1 to 2-8
The procedure of examples 1 to 13 was repeated, except that the dinitrile compound was added as shown in Table 2 and the type of the dinitrile compound and the mass percent thereof were adjusted as shown in Table 2, and the mass percent of the base solvent was changed, whereby the mass percent of the lithium salt was unchanged.
Examples 3-1 to 3-24
The procedure of examples 1 to 13 was repeated, except that in the < preparation of electrolyte > fluorocarbonate was added as shown in Table 3, and the kind of fluorocarbonate and the mass% thereof were adjusted as shown in Table 3, the mass% of the nonaqueous organic solvent was changed, and the mass% of the lithium salt was unchanged.
Examples 4-1 to 4-21
The procedure of examples 3 to 11 was repeated, except that the carboxylic acid ester compound shown in Table 4 was used instead of the non-fluorocarbonic acid ester dipropyl carbonate in the < preparation of electrolyte solution >, and the type of the carboxylic acid ester compound and the mass% thereof were adjusted as shown in Table 4, whereby the mass% of the non-fluorocarbonic acid ester carbonate was changed and the mass% of the lithium salt was unchanged.
Example 5-1
The procedure of example 2-1 was repeated, except that in the < preparation of electrolyte > fluorocarbonate fluoroethylene carbonate (FEC) was added as shown in Table 5, and the mass percentage of the fluorocarbonate was adjusted as shown in Table 5, so that the mass percentage of the nonaqueous organic solvent was changed, and the mass percentage of the lithium salt was unchanged.
Example 5-2
The procedure of example 2-1 was repeated except that in the < preparation of electrolyte > the carboxylic acid ester compound acetic acid-2, 2-difluoroethyl ester was used instead of the non-fluorocarbonic acid ester dipropyl carbonate and the mass percentage of the carboxylic acid ester compound was adjusted as shown in Table 5, so that the mass percentage of the non-aqueous organic solvent was changed and the mass percentage of the lithium salt was unchanged.
Examples 5 to 3
The procedure of example 5-2 was repeated except that in the < preparation of electrolyte > fluorocarbonate FEC was added as shown in Table 5, and the mass percentage of the fluorocarbonate was adjusted as shown in Table 5, so that the mass percentage of the nonaqueous organic solvent was changed, and the mass percentage of the lithium salt was unchanged.
Comparative example 1
The procedure of example 1-1 was repeated, except that the mass percentage of the non-aqueous organic solvent and the mass percentage of the lithium salt were changed without adding the compound represented by the formula (I) in the < preparation of electrolyte >.
Comparative examples 2 to 3
The procedure of example 1-1 was repeated except that the mass percentage of the compound represented by the formula (I) was changed as shown in Table 1 in the < preparation of electrolyte >, and the mass percentage of the nonaqueous organic solvent was changed.
Comparative example 4
The procedure of examples 3 to 11 was repeated, except that the compound represented by the formula (I) was not added to the solution < preparation of electrolyte >, and the mass percentage of the nonaqueous organic solvent was changed, so that the mass percentage of the lithium salt was not changed.
The preparation parameters and performance parameters of each example and comparative example are shown in tables 1 to 5.
TABLE 1
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Note that: the "/" in table 1 indicates no relevant parameters.
As can be seen from examples 1-1 to 1-42 and comparative examples 1 to 3, the application of the electrolyte including the compound represented by formula (I) to a lithium ion battery having higher cycle capacity retention, lower high temperature storage expansion rate and higher 2C discharge capacity retention, indicates that the lithium ion battery has better cycle performance, high temperature storage performance and kinetic performance.
From examples 1 to 36 to examples 1 to 42, comparative example 2, it can be seen that when x is too small, the cycle capacity retention rate of the lithium ion battery is small, the high-temperature storage expansion rate is large, and the 2C discharge capacity retention rate is small, indicating that the cycle performance, the high-temperature storage performance, and the kinetic performance of the lithium ion battery cannot be improved when x is too small. From examples 1 to 36 to examples 1 to 42, and comparative example 3, it can be seen that when x is too large, the cycle capacity retention rate of the lithium ion battery is small although the high temperature storage expansion rate of the lithium ion battery is small and the 2C discharge capacity retention rate is large, indicating that it is difficult to consider the cycle performance, the high temperature storage performance and the kinetic performance of the lithium ion battery when x is too large. When x is more than or equal to 0.01 and less than or equal to 10, the lithium ion battery has higher cycle capacity retention rate, lower high-temperature storage expansion rate and higher 2C discharge capacity retention rate. When x is more than or equal to 0.1 and less than or equal to 5, the lithium ion battery can have a lower high-temperature storage expansion rate and a higher 2C discharge capacity retention rate and a higher cyclic capacity retention rate, and the compound shown in the formula (I) is additionally added, so that the cyclic capacity retention rate and the 2C discharge capacity retention rate of the lithium ion battery can be reduced although the high-temperature storage expansion rate of the lithium ion battery can be smaller. Therefore, the regulation and control of x is in the range of the application, and the lithium ion battery has higher cycle capacity retention rate while having lower high-temperature storage expansion rate and higher 2C discharge capacity retention rate, namely the lithium ion battery has better cycle performance while having good high-temperature storage performance and dynamic performance.
TABLE 2
Note that: the "/" in Table 2 indicates no relevant parameters.
The type of dinitrile compound generally affects the cycle performance, high temperature storage performance and kinetic performance of lithium ion batteries. As can be seen from examples 2-1 to 2-6, the lithium ion battery of the type of the dinitrile compound within the scope of the present application has a higher cycle capacity retention rate, a lower high-temperature storage expansion rate and a higher 2C discharge capacity retention rate, thereby illustrating that the electrolyte further introduces the dinitrile compound in the presence of the compound represented by formula (I), so that the lithium ion battery has good cycle performance, high-temperature storage performance and kinetic performance.
The mass percent of dinitriles generally affects the cycling performance, high temperature storage performance and kinetic performance of lithium ion batteries. As can be seen from examples 1-13, 2-1, 2-7 to 2-8, the lithium ion battery with the mass percent of dinitrile compound within the scope of the application has higher cycle capacity retention, lower high temperature storage expansion rate and higher 2C discharge capacity retention, which indicates that the lithium ion battery has better cycle performance, high temperature storage performance and kinetic performance.
TABLE 3 Table 3
Note that: the "/" in Table 3 indicates no relevant parameters.
The type of fluorocarbonate generally affects the cycle performance, high temperature storage performance and kinetic performance of lithium ion batteries. As can be seen from examples 1-13, 3-1 to 3-7 and 3-11, the lithium ion battery with the fluorocarbonate type within the scope of the present application has a higher cycle capacity retention rate, a lower high temperature storage expansion rate and a higher 2C discharge capacity retention rate, thereby illustrating that the electrolyte further introduces the fluorocarbonate under the condition of containing the compound represented by the formula (I), so that the lithium ion battery has better cycle performance while having good high temperature storage performance and kinetic performance.
The mass percent of the fluorocarbonate generally affects the cycle performance, high temperature storage performance and kinetic performance of the lithium ion battery. As can be seen from examples 3-11, examples 3-16 to examples 3-24, the lithium ion battery with the mass percent of the fluorocarbonate within the range of the present application has higher cycle capacity retention, lower high temperature storage expansion rate and higher 2C discharge capacity retention, indicating that the lithium ion battery has better cycle performance while having good high temperature storage performance and kinetic performance.
The ratio x/y of the values of the mass% x% of the compound of formula (I) to the mass% y% of the fluorocarbonate generally affects the cycle performance, the high-temperature storage performance and the kinetic performance of the lithium ion battery. From examples 3-8 to 3-24, it can be seen that the lithium ion battery with the mass percent of the fluorocarbonate within the scope of the application has higher cycle capacity retention rate, lower high-temperature storage expansion rate and higher 2C discharge capacity retention rate, which indicates that the lithium ion battery has better cycle performance while having good high-temperature storage performance and kinetic performance.
As can be seen from examples 1 to 13, examples 3 to 11 and comparative example 4, when the electrolyte of the lithium ion battery includes only one of the compound represented by formula (I) and the fluorocarbonate, the cyclic capacity retention rate of the lithium ion battery is low, the high-temperature storage expansion rate is high, and the 2C discharge capacity retention rate is low; when the electrolyte of the lithium ion battery comprises the compound shown in the formula (I) and the fluorocarbonate, the lithium ion battery has higher cycle capacity retention rate, lower high-temperature storage expansion rate and higher 2C discharge capacity retention rate, namely the lithium ion battery has better cycle performance while having good high-temperature storage performance and dynamic performance.
TABLE 4 Table 4
/>
Note that: the "/" in Table 4 indicates no relevant parameters.
The type of carboxylic acid ester compound generally affects the cycle performance, high-temperature storage performance and kinetic performance of lithium ion batteries. As can be seen from examples 3-11 and examples 4-1 to 4-16, the lithium ion battery with the types of carboxylic acid ester compounds within the scope of the application has higher cycle capacity retention rate, lower high-temperature storage expansion rate and higher 2C discharge capacity retention rate, and can also reduce the lithium precipitation degree of the lithium ion battery, so that the electrolyte is further introduced with the carboxylic acid ester compounds under the condition of containing the compound shown in the formula (I) and the fluorocarbonate, and the lithium ion battery has better cycle performance, kinetic performance and safety performance while having good high-temperature storage performance.
The mass percent of carboxylic acid ester compounds generally affects the cycle performance, high temperature storage performance and kinetic performance of lithium ion batteries. From examples 4-1, 4-17 to 4-21, it can be seen that the lithium ion battery with the mass percent of the carboxylate compounds within the scope of the application has higher cycle capacity retention rate, lower high-temperature storage expansion rate and higher 2C discharge capacity retention rate, and can reduce the lithium precipitation degree of the lithium ion battery, which indicates that the lithium ion battery has good cycle performance, high-temperature storage performance and dynamic performance, and also has good safety performance.
TABLE 5
Note that: the "/" in Table 5 indicates no relevant parameters.
As can be seen from examples 2-1 and 5-1, when the electrolyte includes the compound shown in formula (I) and the dinitrile compound, further introduction of the fluorocarbonate can make the lithium ion battery have higher cycle capacity retention rate, lower high-temperature storage expansion rate and higher 2C discharge capacity retention rate, which indicates that the lithium ion battery has better cycle performance while having good high-temperature storage performance and kinetic performance.
As can be seen from examples 3-11 and 5-1, when the electrolyte includes the compound shown in formula (I) and the fluorocarbonate, the further introduction of the dinitrile compound can make the lithium ion battery have higher cycle capacity retention rate, lower high-temperature storage expansion rate and higher 2C discharge capacity retention rate, indicating that the lithium ion battery has better cycle performance, high-temperature storage performance and kinetic performance.
As can be seen from examples 2-1 and 5-2, when the electrolyte includes the compound shown in formula (I) and the dinitrile compound, the carboxylic acid ester compound acetic acid-2, 2-difluoroethyl ester is used to replace dipropyl carbonate in the non-fluorinated carbonate, so that the lithium ion battery has higher cycle capacity retention rate, lower high-temperature storage expansion rate and higher 2C discharge capacity retention rate, which indicates that the lithium ion battery has better cycle performance while having good high-temperature storage performance and dynamic performance.
As can be seen from examples 4-11 and examples 5-3, in the case that the electrolyte comprises the compound shown in formula (I) and the fluorocarbonate, the carboxylic acid ester compound acetic acid-2, 2-difluoroethyl ester is used to replace dipropyl carbonate in the non-fluorocarbonate and the dinitrile compound is further introduced, so that the lithium ion battery has higher cycle capacity retention rate, lower high-temperature storage expansion rate and higher 2C discharge capacity retention rate, which indicates that the lithium ion battery has better cycle performance, high-temperature storage performance and kinetic performance.
The foregoing description of the preferred embodiments of the application is not intended to limit the application to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the application are intended to be included within the scope of the application.

Claims (10)

1. An electrolyte for a secondary battery comprising an electrolyte salt, a nonaqueous organic solvent, and a compound represented by formula (I);
wherein R is 1 To R 4 Each independently selected from C 1 -C 8 Alkyl, C 3 -C 8 Cycloalkyl, C 2 -C 8 Alkenyl, phenyl, phenoxy, C 2 -C 10 Alkyl, C containing ether linkage 1 -C 10 Alkoxy or C 2 -C 10 An acyloxy group; the R is 1 To R 4 At least one of which is selected from oxygen-containing groups, said R 1 To R 4 Can be linked to form a ring;
Based on the mass of the electrolyte, the mass percentage of the compound shown in the formula (I) is x.0.01-10.
2. The electrolyte of claim 1, wherein the compound of formula (I) comprises at least one of the following compounds:
3. the electrolyte of claim 1, wherein the electrolyte further comprises a dinitrile compound comprising at least one of succinonitrile, glutaronitrile, methylglutaronitrile, adiponitrile, pimelic nitrile, suberonitrile, nonyldinitrile, or decyldinitrile;
the mass percentage content of the dinitrile compound is 0.5 to 5% based on the mass of the electrolyte.
4. The electrolyte of claim 1, wherein the electrolyte further comprises a fluorocarbonate;
the fluorocarbonate comprises at least one of fluoroethylene carbonate, bis-fluoroethylene carbonate, trifluoromethyl ethylene carbonate, methyl difluoroethyl carbonate, methyl trifluoroethyl carbonate, ethyl trifluoroethyl carbonate, methyl hexafluoroisopropyl carbonate or bis (2, 2-trifluoroethyl) carbonate;
based on the mass of the electrolyte, the mass percentage of the fluorocarbonate is y%, and y is more than or equal to 1 and less than or equal to 50.
5. The electrolyte according to claim 4, wherein 0.005.ltoreq.x/y.ltoreq.1.
6. The electrolyte of claim 1, wherein the electrolysisThe liquid also comprises carboxylic ester compounds; the carboxylic ester compound comprises C 3 -C 10 Carboxylic acid esters or C 3 -C 10 At least one of the halogenated carboxylic acid esters of (a);
the mass percentage content of the carboxylate compound is 1 to 80% based on the mass of the electrolyte.
7. The electrolyte of claim 1, which satisfies at least one of the following characteristics:
(1)0.1≤x≤5；
(2) The electrolyte comprises fluorocarbonate, and the mass percentage of the fluorocarbonate is y% which is more than or equal to 5 and less than or equal to 40 based on the mass of the electrolyte;
(3) The electrolyte comprises a carboxylate compound, wherein the mass percentage content of the carboxylate compound is 10-60% based on the mass of the electrolyte;
(4) The electrolyte comprises a carboxylic ester compound, the carboxylic ester compound comprises beta-propiolactone, gamma-butyrolactone, delta-valerolactone, ethyl acetate, n-propyl acetate, tertiary butyl acetate, methyl propionate, ethyl propionate, propyl propionate, tertiary methyl butyrate at least one of 2, 2-difluoroethyl acetate, 2-trifluoroethyl acetate, hexafluoroisopropyl acetate, 2-difluoroethyl propionate, 2-trifluoroethyl propionate or hexafluoroisopropyl propionate.
8. A secondary battery comprising a positive electrode tab, a negative electrode tab, and the electrolyte of any one of claims 1 to 7.
9. The secondary battery according to claim 8, the negative electrode tab comprising a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, the negative electrode active material layer comprising a negative electrode active material comprising a silicon-based material.
10. An electronic device comprising the secondary battery according to claim 8 or 9.
CN202310744959.5A 2023-06-21 2023-06-21 Electrolyte of secondary battery, secondary battery and electronic device Pending CN116706232A (en)

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