WO2024099377A1 - 一种电解液及包括该电解液的电池 - Google Patents

一种电解液及包括该电解液的电池 Download PDF

Info

Publication number
WO2024099377A1
WO2024099377A1 PCT/CN2023/130570 CN2023130570W WO2024099377A1 WO 2024099377 A1 WO2024099377 A1 WO 2024099377A1 CN 2023130570 W CN2023130570 W CN 2023130570W WO 2024099377 A1 WO2024099377 A1 WO 2024099377A1
Authority
WO
WIPO (PCT)
Prior art keywords
additive
battery
electrolyte
substituted
alkyl
Prior art date
Application number
PCT/CN2023/130570
Other languages
English (en)
French (fr)
Inventor
王海
李素丽
Original Assignee
珠海冠宇电池股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 珠海冠宇电池股份有限公司 filed Critical 珠海冠宇电池股份有限公司
Publication of WO2024099377A1 publication Critical patent/WO2024099377A1/zh

Links

Classifications

    • 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
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • 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

Definitions

  • the present invention relates to an electrolyte and a battery comprising the electrolyte, and belongs to the technical field of lithium ion batteries.
  • Lithium-ion batteries have advantages such as high specific energy density and long cycle life, so they are widely used in various electronic products. In recent years, they have also been widely used in electric vehicles, various electric tools, and energy storage devices. With the improvement of people's living standards and the yearning for a better life, the upgrade of battery application scenarios has put forward higher requirements for battery performance, especially for the balance between high temperature performance and fast charging performance of batteries.
  • the present disclosure provides an electrolyte and a battery comprising the electrolyte.
  • the electrolyte has higher oxidation resistance, and some oxidation products can undergo polymerization reaction with the solvent to form protection at the positive and negative electrodes.
  • the use of the electrolyte can improve the high-temperature cycle performance and high-temperature storage performance of the battery, while also taking into account the fast charging performance of the battery.
  • An electrolyte comprises an organic solvent, a lithium salt and a functional additive, wherein the functional additive comprises a first additive, and the first additive is a cyclic silane compound containing an unsaturated bond.
  • the cyclic silane compound containing an unsaturated bond includes an unsaturated double bond and a cyclic siloxy group (-Si-O-).
  • the first additive is selected from at least one of the compounds shown in Formula I:
  • R1 is selected from an alkyl group; m is an integer between 2 and 12; and n is an integer between 0 and 10.
  • R 1 is selected from C 1-12 alkyl, preferably R 1 is selected from C 1-6 alkyl, for example, R 1 is selected from C 1-3 alkyl, illustratively, R 1 is selected from methyl.
  • m is an integer between 2 and 6, and illustratively, m is 2, 3, 4, 5 or 6.
  • Different m has different stability of the ring structure in the first additive, different oxidation resistance, and different number of unsaturated bonds.
  • m is an integer between 2 and 6, the stability of the ring structure in the first additive is good, the oxidation resistance is strong, and the polymerization degree of the first additive can be enhanced, so that the protection formed on the negative electrode surface is better.
  • n is an integer between 0 and 5, and illustratively, n is 0, 1, 2, 3, 4 or 5. With different n, the stability of the unsaturated bonds in the first additive is different, and the oxidation resistance is also different. When n is an integer between 0 and 5, the stability of the unsaturated bonds in the first additive is better and the oxidation resistance is stronger.
  • n is an integer from 1 to 5, and n is 1, 2, 3, 4 or 5.
  • the polymer between the molecules formed by the first additive is relatively dense, which will affect the insertion and extraction of lithium ions, thereby affecting the ion conductivity;
  • n is larger (for example, n>3), the polymer between the molecules formed by the first additive is relatively sparse, which will affect the protection of the negative electrode to a certain extent.
  • the polymer between the molecules formed by the first additive is more suitable, which can not only form a strong protection for the negative electrode, but also will not affect the insertion and extraction of lithium ions.
  • the first additive is selected from at least one of the compounds represented by Formula I-1 to Formula I-3:
  • the first additive has good stability, high oxidation resistance, and high degree of polymerization, and is more conducive to participating in film formation on the surface of the negative electrode.
  • the functional additive further includes a second additive, and the second additive is selected from at least one of fluorinated cyclic carbonate compounds.
  • the second additive can act together with the first additive on the surface of the negative electrode to form a tight and repairable SEI structure layer without increasing impedance. The two work together to protect the positive and negative electrodes, prevent further decomposition of the electrolyte, and improve the fast charging stability of the electrolyte.
  • the weight ratio of the first additive to the second additive is 1:(1-20) (e.g., 1:1, 1:3, 1:5, 1:8, 1:10, 1:13, 1:15, 1:18, 1:20).
  • the weight ratio of the first additive to the second additive is 1:(6-15).
  • the fluorinated cyclic carbonate compound has at least one of the structural formulas shown in Formula II:
  • R 2 is absent or -CH 2 -;
  • R 3 and R 4 are the same or different and are independently selected from halogen, alkyl, and alkyl substituted with halogen.
  • R 3 and R 4 are the same or different, and are independently selected from halogen, C 1-12 alkyl, and halogen-substituted C 1-12 alkyl.
  • R 3 and R 4 are the same or different, and are independently selected from halogen, C 1-6 alkyl, and halogen-substituted C 1-6 alkyl.
  • R 3 and R 4 are the same or different, and are independently selected from fluorine, C 1-3 alkyl, and fluorine-substituted C 1-3 alkyl.
  • the second additive is selected from at least one of the compounds represented by Formula II-1 to Formula II-8:
  • the second additive when the second additive is selected from compounds containing more F substitution, it can generate more LiF on the surface of the negative electrode to obtain a battery with low impedance.
  • the weight content of the first additive is 0.1wt% to 5wt%, for example, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.2wt%, 1.3wt%, 1.5wt%, 1.6wt%, 1.8wt%, 2wt%, 2.2wt%, 2.4wt%, 2.5wt%, 2.6wt%, 2.8wt%, 3wt%, 3.3wt%, 3.5wt%, 3.8wt%, 4wt%, 4.2wt%, 4.5wt%, 4.8wt% or 5wt%.
  • the weight content of the second additive is 5wt% to 15wt%, for example, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt% or 15wt%.
  • the first additive can be prepared by a method known in the art, or can be purchased through commercial channels.
  • the second additive can be prepared by a method known in the art, or can be purchased through commercial channels.
  • the functional additive further includes a third additive, and the third additive is selected from at least one of 1,3-propylene sultone, lithium difluorooxalatoborate, lithium difluorophosphate, and lithium difluorobisoxalatophosphate.
  • the weight content of the third additive is 2wt% to 8wt%, for example, 2wt%, 2.2wt%, 2.4wt%, 2.5wt%, 2.6wt%, 2.8wt%, 3wt%, 3.3wt%, 3.5wt%, 3.8wt%, 4wt%, 4.2wt%, 4.5wt%, 4.8wt%, 5wt%, 6wt%, 7wt% or 8wt%.
  • the introduction of the third additive can participate in the formation of SEI film in the early stage of formation, play a role in protecting the negative electrode, and at the same time, it can continuously repair the damaged SEI film in the later stage of the cycle, thereby improving the electrochemical performance of the battery.
  • the functional additive further includes a fourth additive, and the fourth additive has at least one of the structures shown in Formula III:
  • R5 and R6 may be the same or different, and are independently selected from substituted or unsubstituted C1-C20 alkyl groups, substituted or unsubstituted C2-C20 olefin groups, substituted or unsubstituted C2-C20 alkynyl groups, substituted or unsubstituted C3-C20 cycloalkyl groups, substituted or unsubstituted phenyl groups, substituted or unsubstituted biphenyl groups, substituted or unsubstituted C6-C26 phenylalkyl groups, substituted or unsubstituted C6-C26 condensed aromatic groups, hydrogen, and halogen; the substituted substituents are selected from one or more of the halogens.
  • a 1 , A 2 , A 3 , A 4 , C 1 , and C 2 may be the same or different, and are each independently selected from C, S, N, and O;
  • x is an integer from 0 to 2 (for example, n is 0, 1, or 2).
  • x is zero.
  • the halogen includes one or more of F, Cl, Br and I.
  • SEI film components that are all linear alkyl lithium carbonates.
  • the alkyl lithium carbonate attached to LiC is unstable at high temperatures and decomposes to generate gases (such as CO2 , etc.) to cause battery swelling.
  • the fourth additive is a polycyclic compound. This structure allows the fourth additive to be preferentially reduced in the negative electrode solvent to form a film containing alkyl sulfonic acid substances.
  • the film has defects, it has a certain two-dimensional structure and is still relatively stable when attached to LiC at high temperatures. It can effectively protect the negative electrode, thereby improving the safety performance of the battery when fully charged.
  • the fourth additive when the fourth additive is coordinated with the first additive and the second additive, the fourth additive forms a defective two-dimensional structure on the surface of the negative electrode when the voltage is low. As the voltage increases, the fourth additive forms a defective two-dimensional structure on the surface of the negative electrode. With the increase of voltage, the first additive and the second additive form a linear structure of alkyl lithium carbonate on the surface of the negative electrode.
  • the alkyl lithium carbonate can fill the defects of the two-dimensional structure to form a high-strength and tough SEI film with a network structure that is stably attached to LiC, which can further improve the safety performance of the fully charged battery at high temperature.
  • the weight of the first additive: the weight of the second additive: the weight of the fourth additive is 1:(1-20):(0.5-5) (for example, 1:1:0.5, 1:3:1, 1:6:1.5, 1:8:2, 1:10:2, 1:13:2, 1:13:5, 1:15:2, 1:15:5, 1:18:4, 1:18:3, 1:20:5).
  • the weight of the first additive the weight of the second additive: the weight of the fourth additive is 1:(6-15):(1-3).
  • the fourth additive includes at least one of the compounds represented by Formula III-1 to Formula III-5:
  • the weight content of the fourth additive is 0.5wt%-5wt% (for example, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%).
  • the weight content of the fourth additive is 1 wt%-3 wt%.
  • the additive further includes a nitrile additive
  • the nitrile additive includes one or more of succinonitrile (SN), adiponitrile (ADN) and 1,3,6-hexanetrinitrile (HTCN).
  • the weight content of the nitrile additive is 3wt%-8wt% (eg, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%).
  • the lithium salt is selected from one or more of lithium hexafluorophosphate (LiPF 6 ), lithium difluorophosphate (LiPO 2 F 2 ), lithium difluorooxalatoborate (LiDFOB), lithium bis(trifluoromethylsulfonyl imide), lithium difluorobis(oxalatophosphate), lithium tetrafluoroborate, lithium bis(oxalatoborate), lithium hexafluoroantimonate, lithium hexafluoroarsenate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(pentafluoroethylsulfonyl)imide, tris(trifluoromethylsulfonyl)methyllithium or lithium bis(trifluoromethylsulfonyl)imide.
  • LiPF 6 lithium hexafluorophosphate
  • LiPO 2 F 2 lithium difluorooxalatoborate
  • the weight content of the lithium salt is 10wt% to 20wt% (for example, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%).
  • the organic solvent is selected from carbonates and/or carboxylates
  • the carbonates are selected from one or more of the following fluorinated or unsubstituted solvents: ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate, diethyl carbonate (DEC), and ethyl methyl carbonate
  • the carboxylates are selected from one or more of the following fluorinated or unsubstituted solvents: propyl acetate, n-butyl acetate, isobutyl acetate, n-amyl acetate, isoamyl acetate, propyl propionate (PP), ethyl propionate (EP), methyl butyrate, and ethyl butyrate.
  • the weight content of the organic solvent is 60wt% to 79wt% (e.g., 60wt%, 62wt%, 65wt%, 67wt%, 70wt%, 72wt%, 75wt%, 77wt%, 79wt%).
  • the electrolyte is used in a lithium-ion battery.
  • the present disclosure also provides a battery, which includes the above-mentioned electrolyte.
  • the charge and discharge range of the battery is 3V-4.53V (eg, 3V, 3.5V, 4V, 4.5V, 4.53V).
  • the charging and discharging range of the battery disclosed in the present invention is 3V to 4.5V.
  • the battery further includes a positive electrode sheet containing a positive electrode active material, a negative electrode sheet containing a negative electrode active material, and a separator.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer coated on one side or both sides of the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active material, a conductive agent and a binder.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on one side or both sides of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material, a conductive agent and a binder.
  • the mass percentage of each component in the positive electrode active material layer is: 80wt% to 99.8wt% (for example, 80wt%, 85wt%, 90wt%, 95wt%, 99.8wt%) of positive electrode active material, 0.1wt% to 10wt% (for example, 0.1wt%, 0.5wt%, 1wt%, 3wt%, 5wt%, 7wt%, 10wt%) of conductive agent, 0.1wt% to 10wt% (for example, 0.1wt%, 0.5wt%, 1wt%, 3wt%, 5wt%, 7wt%, 10wt%) of binder.
  • 80wt% to 99.8wt% for example, 80wt%, 85wt%, 90wt%, 95wt%, 99.8wt%
  • 0.1wt% to 10wt% for example, 0.1wt%, 0.5wt%, 1wt%, 3wt%, 5wt%
  • the mass percentage of each component in the positive electrode active material layer is: 90wt% to 99.6wt% of positive electrode active material, 0.2wt% to 5wt% of conductive agent, and 0.2wt% to 5wt% of binder.
  • the mass percentage of each component in the negative electrode active material layer is: 80wt% to 99.8wt% (for example, 80wt%, 85wt%, 90wt%, 95wt%, 99.8wt%) of negative electrode active material, 0.1wt% to 10wt% (for example, 0.1wt%, 0.5wt%, 1wt%, 3wt%, 5wt%, 7wt%, 10wt%) of conductive agent, and 0.1wt% to 10wt% (for example, 0.1wt%, 0.5wt%, 1wt%, 3wt%, 5wt%, 7wt%, 10wt%) of binder.
  • 80wt% to 99.8wt% for example, 80wt%, 85wt%, 90wt%, 95wt%, 99.8wt%
  • 0.1wt% to 10wt% for example, 0.1wt%, 0.5wt%, 1wt%, 3wt%, 5wt
  • the mass percentage of each component in the negative electrode active material layer is: 90wt% to 99.6wt% of negative electrode active material, 0.2wt% to 5wt% of conductive agent, and 0.2wt% to 5wt% of binder.
  • the negative electrode active material is selected from at least one of artificial graphite, natural graphite, mesophase carbon microbeads, hard carbon, soft carbon, and silicon-based negative electrode materials.
  • the positive electrode active material is selected from one or more of transition metal lithium oxide, lithium iron phosphate, lithium manganate, lithium manganese iron phosphate, and lithium vanadium phosphate; the chemical composition of the transition metal lithium oxide is The formula is Li1 +xNiyCozM ( 1-yz) O2 , wherein -0.1 ⁇ x ⁇ 1; 0 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 1, and 0 ⁇ y+z ⁇ 1; wherein M is one or more of Mg, Zn, Ga, Ba, Al, Fe, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo, and Zr.
  • the conductive agent is selected from one or more of conductive carbon black (SP), carbon nanotubes (CNTs) (e.g., single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes), acetylene black, Ketjen black, conductive graphite, conductive carbon fiber and metal powder.
  • SP conductive carbon black
  • CNTs carbon nanotubes
  • SWCNTs single-walled carbon nanotubes
  • Ketjen black e.g., Ketjen black
  • conductive graphite conductive carbon fiber and metal powder.
  • the binder is selected from one or more of polyvinylidene fluoride (PVDF), styrene-butadiene rubber, lithiated polyacrylic acid (Li-PAA), sodium carboxymethyl cellulose and polyethylene oxide.
  • PVDF polyvinylidene fluoride
  • Li-PAA lithiated polyacrylic acid
  • sodium carboxymethyl cellulose sodium carboxymethyl cellulose and polyethylene oxide.
  • the capacity retention rate is greater than or equal to 69%, and the thickness expansion rate is less than or equal to 8%.
  • the capacity retention rate of the battery after cycling for 300 cycles at 45° C. is greater than or equal to 80%.
  • the battery has a capacity retention rate of greater than or equal to 76% at a 3C rate discharge.
  • the capacity retention rate of the battery after 800 cycles at 45° C. is greater than or equal to 64%.
  • the present disclosure provides an electrolyte and a battery including the electrolyte.
  • the cyclic silane compounds containing unsaturated bonds in the electrolyte have higher stability than chain silane compounds containing unsaturated bonds due to their ring-forming structural characteristics.
  • the silicon-carbon bonds formed by the cyclic silicon atoms and the branched molecules are broken due to oxidative decomposition, and the broken silicon-oxygen bonds are further oxidized, wherein some of the oxidation products can react with the organic solvent (such as EC) in the electrolyte to generate a polymer that can form a protective film not only on the positive electrode surface, but also on the negative electrode surface.
  • the cyclic silane compounds containing unsaturated bonds can also generate a compound containing -Si-OF- bonds after continuous oxidation, and the compound containing -Si-OF- bonds can participate in the film formation on the positive and negative electrode surfaces.
  • the thermal stability of the SEI film at high temperature and full charge is poor, and it is easy to deform and increase the pores, resulting in further reduction of the solvent at the negative electrode.
  • the unsaturated double bonds on the side chains of cyclic silane compounds containing unsaturated bonds can also undergo polymerization on the surface of the negative electrode to form a mesh protective film.
  • the formed mesh protective film has a certain toughness, which can enhance the firmness of the SEI film and inhibit the deformation of the SEI film, significantly improving the high-temperature storage performance and high-temperature cycle performance of the battery. At the same time, it can Take into account the battery's rate performance.
  • the lithium-ion battery of the present disclosure includes a negative electrode sheet, an electrolyte, a positive electrode sheet, a separator and an outer package.
  • the positive electrode sheet, the separator and the negative electrode sheet are stacked to obtain a battery cell, or the positive electrode sheet, the separator and the negative electrode sheet are stacked and/or wound to obtain a battery cell, and the battery cell is placed in an outer package, and the electrolyte is injected into the outer package to obtain the lithium-ion battery of the present disclosure.
  • the lithium ion batteries of Examples 1 to 16 and Comparative Examples 1 to 5 are prepared by the following steps:
  • the positive electrode active materials of lithium cobalt oxide (LiCoO 2 ), polyvinylidene fluoride (PVDF), SP (superP) and carbon nanotubes (CNT) are mixed in a mass ratio of 96:2:1.5:0.5, and N-methylpyrrolidone (NMP) is added, and the mixture is stirred under the action of a vacuum mixer until the mixed system becomes a positive electrode active slurry with uniform fluidity; the positive electrode active slurry is evenly coated on both surfaces of an aluminum foil; the coated aluminum foil is dried, Then the required positive electrode sheet is obtained through rolling and slitting.
  • NMP N-methylpyrrolidone
  • the negative electrode active materials artificial graphite, sodium carboxymethyl cellulose (CMC-Na), styrene-butadiene rubber, conductive carbon black (SP) and single-walled carbon nanotubes (SWCNTs) are mixed in a mass ratio of 94.5:2.5:1.5:1:0.5, deionized water is added, and the negative electrode active slurry is obtained under the action of a vacuum mixer; the negative electrode active slurry is evenly coated on both surfaces of the copper foil; the coated copper foil is dried at room temperature, and then transferred to an oven at 80°C for drying for 10 hours, and then cold pressed and cut to obtain the negative electrode sheet.
  • EC/PC/DEC/PP were uniformly mixed in a mass ratio of 10/10/20/60, and then 13wt% of fully dried lithium hexafluorophosphate (LiPF 6 ) based on the total mass of the electrolyte was quickly added thereto, and after dissolution, 4wt% of 1,3-propane sultone based on the total mass of the third additive of the electrolyte was added.
  • the electrolyte also included commonly used nitrile additives (content of 5%), including SN, ADN, and HTCN, and their corresponding proportions were 1.5%, 1%, and 2.5%.
  • the first additive and the second additive were added according to the additives shown in Table 1, and the electrolytes of Examples 1 to 7 and Comparative Examples 1 to 5 were prepared after uniform mixing.
  • the positive electrode sheet of step 1), the negative electrode sheet of step 2) and the separator are stacked in the order of positive electrode sheet, separator and negative electrode sheet, and then wound to obtain a battery cell; the battery cell is placed in an outer packaging aluminum foil, and the electrolyte of step 3) is injected into the outer packaging. After vacuum packaging, standing, forming, shaping, sorting and other processes, a lithium-ion battery is obtained.
  • the lithium-ion batteries obtained in the examples and comparative examples were subjected to the following performance tests, respectively.
  • the test results are shown in Table 2.
  • the divided battery cells were charged and discharged for 1000 cycles at 45°C at a rate of 1C within the charge and discharge cut-off voltage range.
  • the discharge capacity of the first week of the test was calculated as x1mAh
  • the discharge capacity of the Nth cycle was calculated as y1mAh.
  • the divided cells are charged at 0.5C to the upper cut-off voltage, and the voltage is kept constant at 0.05C.
  • the fully charged samples are discharged at a current of 3C, and the discharge capacity retention rate is then calculated.
  • the cyclic silane compound containing unsaturated bonds as the first additive has high stability due to its ring-forming structural characteristics, and under high voltage, the silicon-carbon bond formed by the cyclic silicon atom and the branched molecule is broken due to oxidative decomposition, and the broken silicon-oxygen bond is further oxidized, and some of the oxidation products can react with the organic solvent (such as EC) in the electrolyte to form a polymer that can form a protective film not only on the positive electrode surface, but also on the negative electrode surface; the cyclic silane compound containing unsaturated bonds can also generate a compound containing -Si-O-F- bonds after continuous oxidation, and the compound containing -Si-O-F- bonds can participate in the film formation on the positive and negative electrode surfaces.
  • the organic solvent such as EC
  • the thermal stability of the SEI film at high temperature and full charge is poor, and it is easy to deform and increase the pores, resulting in further reduction of the solvent at the negative electrode, and the unsaturated double bonds on the side chains of the cyclic silane compound containing unsaturated bonds can also undergo polymerization on the negative electrode surface to form a mesh protective film, and the formed mesh protective film has a certain toughness, which can enhance the firmness of the SEI film and inhibit the deformation of the SEI film.
  • the introduced second additive can work together with the first additive on the surface of the negative electrode to form a tight and repairable SEI structure layer without increasing impedance. The two work synergistically to protect the positive and negative electrodes, prevent further decomposition of the electrolyte, and improve the fast charging stability of the electrolyte.

Landscapes

  • 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

提供了一种电解液及包括该电解液的电池，所述电解液中的含有不饱和键的环状硅烷类化合物具有较高的稳定性，且在高电压下由于氧化分解作用使得环状硅原子与支链分子形成的硅碳键断裂，断裂后的硅氧键进一步被氧化，其中部分氧化产物又可以跟电解液中的有机溶剂(如EC)发生聚合反应，生成的聚合物不光可以在正极表面形成保护膜，也可以在负极表面形成保护膜；所述电解液的使用能够提高所述电池的高温循环性能和高温存储性能，同时还能兼顾电池的快充性能和高温循环稳定性。

Description

一种电解液及包括该电解液的电池 技术领域
本公开涉及一种电解液及包括该电解液的电池，属于锂离子电池技术领域。
发明背景
锂离子电池具备比能量密度较大、循环寿命长等优点，因此被广泛应用于各类电子产品中，近年来还被大量用于电动车辆和各种电动工具、储能装置中。随着人们生活水平的提高和对更美好生活的向往，对电池应用场景的升级，对电池的性能提出了更高的要求，特别是对电池的高温性能和快充性能的兼顾提出了更高的要求。
发明内容
为了解决现有技术的不足，本公开提供一种电解液及包括该电解液的电池，所述电解液具有更高的耐氧化性，部分氧化产物可以与溶剂发生聚合反应，在正负极形成保护，所述电解液的使用能够提高所述电池的高温循环性能和高温存储性能，同时还能兼顾电池的快充性能。
本公开目的是通过如下技术方案实现的：
一种电解液，所述电解液包括有机溶剂、锂盐以及功能添加剂，其中，所述功能添加剂包括第一添加剂，所述第一添加剂为含有不饱和键的环状硅烷类化合物。
在一实例中，所述含有不饱和键的环状硅烷类化合物中包括不饱和双键和环状硅氧基(-Si-O-)。
在一实例中，所述第一添加剂选自式I所示化合物中的至少一种：
式I中，R1选自烷基；m为2～12之间的整数；n为0～10之间的整数。
在一实例中，R1选自C1-12烷基，优选为R1选自C1-6烷基，例如为R1选自C1-3烷基，示例性地，R1选自甲基。
在一实例中，m为2～6之间的整数，示例性地，m为2、3、4、5或6。m不同，所述第一添加剂中环结构的稳定性不同，耐氧化性也不同，不饱和键数量不同，当m为2～6之间的整数时，第一添加剂中环结构的稳定性较好，耐氧化性强，同时还能增强第一添加剂的聚合程度，使其在负极表面形成的保护更优异。
在一实例中，n为0～5之间的整数，示例性地，n为0、1、2、3、4或5。n不同，所述第一添加剂中不饱和键的稳定性不同，耐氧化性也不同，当n为0～5之间的整数时，第一添加剂中不饱和键的稳定性较好，耐氧化性强。
在一实例中，n为1～5的整数，n为1、2、3、4或5。
在一实例中，n≤3。当n＝0时，第一添加剂形成的分子之间的聚合物比较致密，会影响锂离子的嵌入嵌出，从而影响离子的传导性能；当n较大(例如，n＞3)时，第一添加剂形成的分子之间的聚合物比较稀松，会在一定程度上影响对负极的保护作用。当0＜n≤3时，所述第一添加剂形成的分子之间的聚合物比较适宜，既可以对负极形成较强的保护，又不会影响锂离子的嵌入嵌出。
在一实例中，所述第一添加剂选自式I-1～式I-3所示的化合物中的至少一种：
此时，所述第一添加剂的稳定性好，耐氧化性高，聚合程度高，更有利于在负极表面参与成膜。
在一实例中，所述功能添加剂还包括第二添加剂，所述第二添加剂选自氟代环状碳酸酯类化合物中的至少一种。第二添加剂可以与第一添加剂共同作用在负极表面，形成紧密可修复的SEI结构层但又不增加阻抗，两者协同作用共同保护正负极，阻止电解液进一步分解，提高电解液的快充稳定性能。
在一实例中，所述第一添加剂的重量与所述第二添加剂的重量之比为1:(1-20)(例如，1:1、1:3、1:5、1:8、1:10、1:13、1:15、1:18、1:20)。
在一实例中，所述第一添加剂的重量与所述第二添加剂的重量之比为1:(6-15)。
在一实例中，所述氟代环状碳酸酯类化合物具有式II所示结构式中的至少一种：
式II中，R2为不存在或-CH2-；R3、R4相同或不同，彼此独立地选自卤素、烷基、卤素取代的烷基。
在一实例中，R3、R4相同或不同，彼此独立地选自卤素、C1-12烷基、卤素取代的C1-12烷基。
在一实例中，R3、R4相同或不同，彼此独立地选自卤素、C1-6烷基、卤素取代的C1-6烷基。
在一实例中，R3、R4相同或不同，彼此独立地选自氟、C1-3烷基、氟取代的C1-3烷基。
在一实例中，所述第二添加剂选自式II-1～式II-8所示的化合物中的至少一种：

在一实例中，所述第二添加剂选自含有较多F取代的化合物时，其能够在负极表面生成更多的LiF，获得低阻抗的电池。
在一实例中，以所述电解液的总重量为基准，所述第一添加剂的重量含量为0.1wt％～5wt％，例如为0.1wt％、0.2wt％、0.3wt％、0.4wt％、0.5wt％、0.6wt％、0.7wt％、0.8wt％、0.9wt％、1wt％、1.2wt％、1.3wt％、1.5wt％、1.6wt％、1.8wt％、2wt％、2.2wt％、2.4wt％、2.5wt％、2.6wt％、2.8wt％、3wt％、3.3wt％、3.5wt％、3.8wt％、4wt％、4.2wt％、4.5wt％、4.8wt％或5wt％。
在一实例中，以所述电解液的总重量为基准，所述第二添加剂的重量含量为5wt％～15wt％，例如为5wt％、6wt％、7wt％、8wt％、9wt％、10wt％、11wt％、12wt％、13wt％、14wt％或15wt％。
在一实例中，所述第一添加剂可以采用本领域已知的方法制备得到，也可以通过商业途径购买获得。
在一实例中，所述第二添加剂可以采用本领域已知的方法制备得到，也可以通过商业途径购买获得。
在一实例中，所述功能添加剂还包括第三添加剂，所述第三添加剂选自1,3-丙烯磺酸内酯、二氟草酸硼酸锂、二氟磷酸锂、二氟二草酸磷酸锂中的至少一种。
在一实例中，以所述电解液的总重量为基准，所述第三添加剂的重量含量为2wt％～8wt％，例如为2wt％、2.2wt％、2.4wt％、2.5wt％、2.6wt％、2.8wt％、3wt％、3.3wt％、3.5wt％、3.8wt％、4wt％、4.2wt％、4.5wt％、4.8wt％、5wt％、6wt％、7wt％或8wt％。第三添加剂的引入可以在化成初期参与生成SEI膜，起到对负极保护的作用，同时其在循环后期还可以不断的对破损的SEI膜进行修复，从而提高电池的电化学性能。
在一实例中，所述功能性添加剂还包括第四添加剂，所述第四添加剂具有式III所示结构中至少一种：
其中，R5、R6可以相同或不同，各自独立地选自被取代或未被取代的C1～C20的烷烃基、取代或未被取代的C2～C20的烯烃基、取代或未被取代的C2～C20的炔烃基、被取代或未被取代的C3～C20的环烷基、被取代或未被取代的苯基、被取代或未被取代的联苯基、被取代或未被取代的C6～C26的苯烷基、被取代或未被取代的C6～C26的稠环芳烃基、氢、卤素；所述取代的取代基选自卤素中的一种或多种。
其中，A1、A2、A3、A4、C1、C2可以相同或不同，各自独立地选自C、S、N、O；
其中，x为0～2的整数(例如，n为0、1、2)。
在一实例中，x为0。
在一实例中，所述卤素包括F、Cl、Br和I中的一种或多种。
传统的成膜添加剂，形成的SEI膜组分均为线性烷基碳酸锂，高温下附在LiC的烷基碳酸锂不稳定，分解生成气体(如CO2等)而产生电池鼓胀。从式III所示结构可以看出，所述第四添加剂为多环化合物，此结构可以使第四添加剂优先在负极溶剂发生还原，形成含有烷基磺酸基物质的膜，虽然该膜有缺陷,但存在着一定的二维结构，附在LiC高温下仍较稳定，可以对负极起到有效的保护作用，从而能够提升电池满电下的安全性能。同时，所述第四添加剂和第一添加剂、第二添加剂协同搭配时，在电压较低时第四添加剂在负极表面形成有缺陷的二维结构，随着 电压的升高第一添加剂和第二添加剂在负极表面又形成线性结构的烷基碳酸锂,该烷基碳酸锂可以填充于二维结构的缺陷中，形成稳定附在LiC具有网络结构的高强韧性的SEI膜，可以进一步提升满电态的电池在高温下的安全性能。
在一实例中，第一添加剂的重量：第二添加剂的重量：第四添加剂的重量为1:(1-20):(0.5-5)(例如，1:1:0.5、1:3:1、1:6:1.5、1:8:2、1:10:2、1:13:2、1:13:5、1:15:2、1:15:5、1:18:4、1:18:3、1:20:5)。
在一实例中，第一添加剂的重量：第二添加剂的重量：第四添加剂的重量为1:(6-15):(1-3)。
在一实例中，所述第四添加剂包括式III-1～式III-5所示化合物中的至少一种：
在一实例中，以所述电解液的总重量为基准，所述第四添加剂的重量含量为0.5wt％-5wt％(例如，0.5wt％、1wt％、1.5wt％、2wt％、2.5wt％、3wt％、3.5wt％、4wt％、4.5wt％、5wt％)。
在一实例中，以所述电解液的总重量为基准，所述第四添加剂的重量含量为1wt％-3wt％。
在一实例中，所述添加剂还包括腈类添加剂，所述腈类添加剂包括丁二腈(SN)、己二腈(ADN)和1,3,6-己烷三腈(HTCN)中的一种或多种。
在一实例中，以所述电解液的总重量为基准，所述腈类添加剂的重量含量为3wt％-8wt％(例如，3wt％、4wt％、5wt％、6wt％、7wt％、8wt％)。
在一实例中，所述锂盐选自六氟磷酸锂(LiPF6)、二氟磷酸锂(LiPO2F2)、二氟草酸硼酸锂(LiDFOB)、双三氟甲基磺酰亚胺锂、二氟双草酸磷酸锂、四氟硼酸锂、双草酸硼酸锂、六氟锑酸锂、六氟砷酸锂、二(三氟甲基磺酰)亚胺锂、二(五氟乙基磺酰)亚胺锂、三(三氟甲基磺酰)甲基锂或二(三氟甲基磺酰)亚胺锂中的一种或两种以上。
在一实例中，以所述电解液的总重量为基准，所述锂盐的重量含量为10wt％～20wt％(例如，10wt％、11wt％、12wt％、13wt％、14wt％、15wt％、16wt％、17wt％、18wt％、19wt％、20wt％)。
在一实例中，所述有机溶剂选自碳酸酯和/或羧酸酯，所述碳酸酯选自氟代或未取代的下述溶剂中的一种或几种：碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸二甲酯、碳酸二乙酯(DEC)、碳酸甲乙酯；所述羧酸酯选自氟代或未取代的下述溶剂中的一种或几种：乙酸丙酯、乙酸正丁酯、乙酸异丁酯、乙酸正戊酯、乙酸异戊酯、丙酸丙酯(PP)、丙酸乙酯(EP)、丁酸甲酯、正丁酸乙酯。
在一实例中，以所述电解液的总重量为基准，所述有机溶剂的重量含量为60wt％～79wt％(例如，60wt％、62wt％、65wt％、67wt％、70wt％、72wt％、75wt％、77wt％、79wt％)。
在一实例中，所述电解液用于锂离子电池。
本公开还提供一种电池，所述电池包括上述的电解液。
在一实例中，所述电池的充放电范围为3V-4.53V(例如，3V、3.5V、4V、4.5V、4.53V)。
本公开电池充放电范围为3V～4.5V。
在一实例中，所述电池还包括含有正极活性物质的正极片、含有负极活性物质的负极片、隔离膜。
在一实例中，所述正极片包括正极集流体和涂覆在正极集流体一侧或两侧表面的正极活性物质层，所述正极活性物质层包括正极活性物质、导电剂和粘结剂。
在一实例中，所述负极片包括负极集流体和涂覆在负极集流体一侧或两侧表面的负极活性物质层，所述负极活性物质层包括负极活性物质、导电剂和粘结剂。
在一实例中，所述正极活性物质层中各组分的质量百分含量为：80wt％～99.8wt％(例如，80wt％、85wt％、90wt％、95wt％、99.8wt％)的正极活性物质、0.1wt％～10wt％例如，0.1wt％、0.5wt％、1wt％、3wt％、5wt％、7wt％、10wt％)的导电剂、0.1wt％～10wt％例如，0.1wt％、0.5wt％、1wt％、3wt％、5wt％、7wt％、10wt％)的粘结剂。
优选地，所述正极活性物质层中各组分的质量百分含量为：90wt％～99.6wt％的正极活性物质、0.2wt％～5wt％的导电剂、0.2wt％～5wt％的粘结剂。
在一实例中，所述负极活性物质层中各组分的质量百分含量为：80wt％～99.8wt％(例如，80wt％、85wt％、90wt％、95wt％、99.8wt％)的负极活性物质、0.1wt％～10wt％例如，0.1wt％、0.5wt％、1wt％、3wt％、5wt％、7wt％、10wt％)的导电剂、0.1wt％～10wt％例如，0.1wt％、0.5wt％、1wt％、3wt％、5wt％、7wt％、10wt％)的粘结剂。
优选地，所述负极活性物质层中各组分的质量百分含量为：90wt％～99.6wt％的负极活性物质、0.2wt％～5wt％的导电剂、0.2wt％～5wt％的粘结剂。
在一实例中，所述负极活性物质选自人造石墨、天然石墨、中间相碳微球、硬碳、软碳、硅基负极材料中的至少一种。
在一实例中，所述的正极活性材料选自过渡金属锂氧化物、磷酸铁锂、锰酸锂、磷酸锰铁锂、磷酸钒锂中的一种或几种；所述过渡金属锂氧化物的化学 式为Li1+xNiyCozM(1-y-z)O2，其中，-0.1≤x≤1；0≤y≤1，0≤z≤1，且0≤y+z≤1；其中，M为Mg、Zn、Ga、Ba、Al、Fe、Cr、Sn、V、Mn、Sc、Ti、Nb、Mo、Zr中的一种或几种。
在一实例中，所述导电剂选自导电炭黑(SP)、碳纳米管(CNT)(例如，单壁碳纳米管(SWCNTs)、多壁碳纳米管)、乙炔黑、科琴黑、导电石墨、导电碳纤维和金属粉中的一种或多种。
在一实例中，所述粘结剂选自聚偏氟乙烯(PVDF)、丁苯橡胶、锂化聚丙烯酸(Li-PAA)、羧甲基纤维素钠和聚氧化乙烯中的一种或多种。
在一实例中，所述电池在85℃存储6小时后容量保持率大于等于69％，厚度膨胀率降小于等于8％。
在一实例中，所述电池在45℃循环300周容量保持率大于等于80％。
在一实例中，所述电池在3C倍率放电容量保持率大于等于76％。
在一实例中，所述电池在45℃循环800周容量保持率大于等于64％。
有益效果：
本公开提供了一种电解液及包括该电解液的电池，所述电解液中的含有不饱和键的环状硅烷类化合物由于其成环的结构特征，因此相比于含有不饱和键的链状硅烷类化合物的稳定性更高，且在高电压下由于氧化分解作用使得环状硅原子与支链分子形成的硅碳键断裂，断裂后的硅氧键进一步被氧化，其中部分氧化产物又可以跟电解液中的有机溶剂(如EC)发生聚合反应，生成的聚合物不光可以在正极表面形成保护膜，也可以在负极表面形成保护膜；含有不饱和键的环状硅烷类化合物还能在持续氧化后生成一种含有-Si-O-F-键的化合物，该含有-Si-O-F-键的化合物可以参与正负极表面的成膜。高温满电下的SEI膜的热稳定性较差，易发生形变以及孔隙增大，导致溶剂在负极的进一步还原，而含有不饱和键的环状硅烷类化合物的支链上的不饱和双键也可以在负极表面发生聚合反应形成网状保护膜，且形成的网状保护膜具有一定的韧性，能够加强SEI膜的牢固性，同时抑制SEI膜的形变，显著改善了电池的高温存储性能和高温循环性能，同时还能 兼顾电池的倍率性能。
具体实施方式
下文将结合具体实施例对本公开做更进一步的详细说明。应当理解，下列实施例仅为示例性地说明和解释本公开，而不应被解释为对本公开保护范围的限制。凡基于本公开上述内容所实现的技术均涵盖在本公开旨在保护的范围内。
下述实施例中所使用的实验方法如无特殊说明，均为常规方法；下述实施例中所用的试剂、材料等，如无特殊说明，均可从商业途径得到。
在本公开的描述中，需要说明的是，术语“第一”、“第二”等仅用于描述目的，而并非指示或暗示相对重要性。
为使本公开的目的、技术方案和优点更加清楚，下面将结合本公开的实施例，对本公开实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本公开一部分实施例，而不是全部的实施例。基于本公开中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本公开保护的范围。
可以理解的是，本公开的锂离子电池包括负极片、电解液、正极片、隔离膜和外包装。将正极片、隔离膜和负极片层叠设置得到电芯或将正极片、隔离膜和负极片层叠设置后，和/或再进行卷绕设置得到电芯，将电芯置于外包装中，向外包装中注入电解液可以得到本公开的锂离子电池。
实施例1～16及对比例1～5
实施例1～16及对比例1～5的锂离子电池通过以下步骤制备得到：
1)正极片制备
将正极活性材料钴酸锂(LiCoO2)、聚偏氟乙烯(PVDF)、SP(superP)和碳纳米管(CNT)按照96:2:1.5:0.5的质量比进行混合，加入N-甲基吡咯烷酮(NMP)，在真空搅拌机作用下搅拌，直至混合体系成均一流动性的正极活性浆料；将正极活性浆料均匀涂覆于铝箔的两个表面；将涂覆好的铝箔烘干， 然后经过辊压、分切得到所需的正极片。
2)负极片制备
将负极活性材料人造石墨、羧甲基纤维素钠(CMC-Na)、丁苯橡胶、导电炭黑(SP)和单壁碳纳米管(SWCNTs)按照质量比94.5:2.5:1.5:1:0.5进行混合，加入去离子水，在真空搅拌机作用下获得负极活性浆料；将负极活性浆料均匀涂覆在铜箔的两个表面；将涂覆好的铜箔在室温下晾干，随后转移至80℃烘箱干燥10h，然后经过冷压、分切得到负极片。
3)电解液的制备
在充满氩气的手套箱中(H2O<0.1ppm，O2<0.1ppm)，将EC/PC/DEC/PP按照10/10/20/60的质量比混合均匀，然后往其中快速加入基于电解液总质量13wt％的充分干燥的六氟磷酸锂(LiPF6)，溶解后加入基于电解液的第三添加剂总质量4wt％的1,3-丙烷磺酸内酯，除此之外，电解液中还包括常用的腈类添加剂(含量为5％)，其中具体包括SN、ADN、HTCN，其相应的比例为1.5％、1％、2.5％,在按照表1所示的添加剂加入第一添加剂和第二添加剂，混合均匀后制备得到实施例1～7和对比例1～5的电解液。
4)锂离子电池的制备
将步骤1)的正极片、步骤2)的负极片和隔离膜按照正极片、隔离膜和负极片的顺序层叠设置后，再进行卷绕得到电芯；将电芯置于外包装铝箔中，将步骤3)的电解液注入外包装中，经过真空封装、静置、化成、整形、分选等工序，获得锂离子电池。
表1实施例和对比例的锂离子电池中电解液添加剂的组成


/表示不存在。
对实施例和对比例获得的锂离子电池分别进行如下性能测试，测试结果见表2。
1)45℃循环性能测试
将分容完的电芯在45℃下按照1C的倍率在充放电截止电压范围内进行充放电循环1000周，测试第1周的放电容量计为x1mAh，第N圈的放电容量计为y1mAh；第N周的容量除以第1周的容量，得到第N周的循环容量保持率R1＝y1/x1。
2)85℃高温存储测试：
将分容完的电芯在常温下以0.5C电流充至4.5V，将满电电池置于85℃环境下6小时，热测厚度膨胀率，恢复室温后，以0.5C大小电流进行放电到3.0V，记录放电容量。
3)3C倍率放电性能测试：
将分容完的电芯在0.5C充电至上限截至电压，恒压到0.05C，在环境温度25℃±5℃下，把完全充电的样品按照3C电流大小进行放电，然后计算放电容量保持率。
4)炉温安全测试：
具体步骤如下：在25℃±5℃环境下，0.2C放电至下限电压(3.0V)；静置10min；0.7C充电至上限电压(4.53V)，截止电流0.02C；在25℃±5℃环境下测试满电状态(100％SOC)电压、内阻、厚度；
将满电电池置于烤箱中，以5±2℃/min温升速率进行升温，当箱内温度达到130℃±2℃后恒温，并持续60min。不爆炸，不起火则表示通过，爆炸或者起火则表示不通过。
测试三只电池，全部通过记录为“3/3”，一次通过、两次通过分别记录为“1/3”、“2/3”(一次通过或两次通过视为不通过)，全部不通过记录为“0/3”。
表2实施例和对比例的锂离子电池的性能测试结果
从表2的实施例1～5以及对比例1～4的测试结果可以看出，单独加入第一添加剂的实施例1～5和单独加入第二添加剂的对比例2～4均对电池的高温性能以及倍率性能有提升。这是因为第一添加剂和第二添加剂均可以在负极表面，能够改善电池的高温存储性能和高温循环性能，同时还能兼顾电池的倍率性能和高温循环稳定性。
表3实施例和对比例的锂离子电池中电解液添加剂的组成
按照上述测试方法对电池进行电池性能测试结果汇总如下表4。
表4实施例和对比例的锂离子电池的性能测试结果

从表2和表4的实施例1～11和对比例1～5测试结果可以看出，同时加入第一添加剂和第二添加剂的实施例6～11相比于其他实施例和对比例，能够显著提升电池的高温性能以及倍率性能。
为了进一步验证第一添加剂、第二添加剂和第四添加剂的组合效果设计如下实验：
表5实施例的电解液中第一添加剂、第二添加剂和第四添加剂的含量
按照上述测试方法对电池进行电池性能测试结果汇总如下表6。
表6实施例和对比例的锂离子电池的性能测试结果

具体地，其作为第一添加剂的含有不饱和键的环状硅烷类化合物由于其成环的结构特征而具有较高的稳定性，且在高电压下由于氧化分解作用使得环状硅原子与支链分子形成的硅碳键断裂，断裂后的硅氧键进一步被氧化，其中部分氧化产物又可以跟电解液中的有机溶剂(如EC)发生聚合反应，生成的聚合物不光可以在正极表面形成保护膜，也可以在负极表面形成保护膜；含有不饱和键的环状硅烷类化合物还能在持续氧化后生成一种含有-Si-O-F-键的化合物，该含有-Si-O-F-键的化合物可以参与正负极表面的成膜。高温满电下的SEI膜的热稳定性较差，易发生形变以及孔隙增大，导致溶剂在负极的进一步还原，而含有不饱和键的环状硅烷类化合物的支链上的不饱和双键也可以在负极表面发生聚合反应形成网状保护膜，且形成的网状保护膜具有一定的韧性，能够加强SEI膜的牢固性，同时抑制SEI膜的形变。引入的第二添加剂可以与第一添加剂共同作用在负极表面，形成紧密可修复的SEI结构层但又不增加阻抗，两者协同作用共同保护正负极，阻止电解液进一步分解，提高电解液的快充稳定性能。
以上，对本公开的实施方式进行了说明。但是，本公开不限定于上述实施方式。凡在本公开的技术方案的基础上，所做的任何修改、等同替换、改进等，均应包含在本公开的保护范围之内。

Claims (15)

  1. 一种电解液，其特征在于，所述电解液包括有机溶剂、锂盐以及功能添加剂，其中，所述功能添加剂包括第一添加剂，所述第一添加剂为含有不饱和键的环状硅烷类化合物；所述第一添加剂选自式I所示化合物中的至少一种：
    式I中，R1选自烷基；m为2～12之间的整数；n为0～10之间的整数。
  2. 根据权利要求1所述的电解液，其特征在于，R1选自C1-12烷基，m为2～6之间的整数，和/或；n为0～5之间的整数。
  3. 根据权利要求1或2所述的电解液，其特征在于，n为1～5的整数，优选地，0＜n≤3。
  4. 根据权利要求1-3中任一项所述的电解液，其特征在于，所述第一添加剂选自式I-1～式I-3所示的化合物中的至少一种：

  5. 根据权利要求1-4中任一项所述的电解液，其特征在于，所述功能添加剂还包括第二添加剂，所述第二添加剂选自氟代环状碳酸酯类化合物中的至少一种；
    优选地，所述氟代环状碳酸酯类化合物具有式II所示结构式中的至少一种：
    式II中，R2为不存在或-CH2-；R3、R4相同或不同，彼此独立地选自卤素、烷基、卤素取代的烷基。
  6. 根据权利要求5所述的电解液，其特征在于，R3、R4相同或不同，彼此独立地选自卤素、C1-12烷基、卤素取代的C1-12烷基；
    优选地，R3、R4相同或不同，彼此独立地选自卤素、C1-6烷基、卤素取代的C1-6烷基；
    优选地，R3、R4相同或不同，彼此独立地选自氟、C1-3烷基、氟取代的C1-3烷基。
  7. 根据权利要求5或6所述的电解液，其特征在于，所述第二添加剂选自式II-1～式II-8所示的化合物中的至少一种：

  8. 根据权利要求1-7中任一项所述的电解液，其特征在于，以所述电解液的总重量为基准，所述第一添加剂的重量含量为0.1wt％～5wt％。
  9. 根据权利要求5-8中任一项所述的电解液，其特征在于，以所述电解液的总重量为基准，所述第二添加剂的重量含量5wt％～15wt％。
  10. 根据权利要求5-9中任一项所述的电解液，其特征在于，所述第一添加剂的重量与所述第二添加剂的重量之比为1:(1-20)，优选为1:(6-15)。
  11. 根据权利要求1-10中任一项所述的电解液，其特征在于，所述功能添加剂还包括第三添加剂，所述第三添加剂选自1,3-丙烯磺酸内酯、二氟草酸硼酸锂、二氟磷酸锂、二氟二草酸磷酸锂中的至少一种；
    和/或，以所述电解液的总重量为基准，所述第三添加剂的重量含量为2wt％～8wt％。
  12. 根据权利要求1-11中任一项所述的电解液，其特征在于，所述功能性添加剂还包括第四添加剂，所述第四添加剂具有式III所示结构中至少一种：
    其中，R5、R6各自独立地选自被取代或未被取代的C1～C20的烷烃基、取代或未被取代的C2～C20的烯烃基、取代或未被取代的C2～C20的炔烃基、被取代或未被取代的C3～C20的环烷基、被取代或未被取代的苯基、被取代或未被取代的联苯基、被取代或未被取代的C6～C26的苯烷基、被取代或未被取代的C6～C26的稠环芳烃基、氢、卤素；所述取代的取代基选自卤素中的一种或多种；
    A1、A2、A3、A4、C1、C2各自独立地选自C、S、N、O；
    x为0～2的整数；
    和/或，以所述电解液的总重量为基准，所述第四添加剂的重量含量为0.5wt％-5wt％。
  13. 根据权利要求1-12中任一项所述的电解液，其特征在于，在一实例中，第一添加剂的重量：第二添加剂的重量：第四添加剂的重量为1:(1-20):(0.5-5)，优选为1:(6-15):(1-3)。
  14. 一种电池，其特征在于，所述电池包括权利要求1-12任一项所述的电解液。
  15. 根据权利要求13所述的电池，其特征在于，所述电池在85℃存储6小时后容量保持率大于等于69％，厚度膨胀率降小于等于8％；
    和/或，所述电池在45℃循环300周容量保持率大于等于80％；
    和/或，所述电池在3C倍率放电容量保持率大于等于76％；
    和/或，所述电池在45℃循环800周容量保持率大于等于64％。
PCT/CN2023/130570 2022-10-25 2023-11-08 一种电解液及包括该电解液的电池 WO2024099377A1 (zh)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
CN202211313788 2022-10-25
CN202211393638.7A CN115763973A (zh) 2022-10-25 2022-11-08 一种电解液及包括该电解液的电池
CN202211393638.7 2022-11-08

Publications (1)

Publication Number Publication Date
WO2024099377A1 true WO2024099377A1 (zh) 2024-05-16

Family

ID=85368274

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2023/130570 WO2024099377A1 (zh) 2022-10-25 2023-11-08 一种电解液及包括该电解液的电池

Country Status (2)

Country Link
CN (1) CN115763973A (zh)
WO (1) WO2024099377A1 (zh)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115763973A (zh) * 2022-10-25 2023-03-07 珠海冠宇电池股份有限公司 一种电解液及包括该电解液的电池

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103825047A (zh) * 2014-02-19 2014-05-28 深圳新宙邦科技股份有限公司 一种用于锂离子电池的电解液
CN111640982A (zh) * 2020-05-18 2020-09-08 珠海冠宇电池股份有限公司 一种锂离子电池用电解液及包括该电解液的锂离子电池
CN114464884A (zh) * 2022-01-21 2022-05-10 珠海冠宇电池股份有限公司 一种电解液及包括该电解液的含硅基负极的电池
CN115036572A (zh) * 2022-06-21 2022-09-09 深圳新宙邦科技股份有限公司 一种锂二次电池
CN115763973A (zh) * 2022-10-25 2023-03-07 珠海冠宇电池股份有限公司 一种电解液及包括该电解液的电池

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103825047A (zh) * 2014-02-19 2014-05-28 深圳新宙邦科技股份有限公司 一种用于锂离子电池的电解液
CN111640982A (zh) * 2020-05-18 2020-09-08 珠海冠宇电池股份有限公司 一种锂离子电池用电解液及包括该电解液的锂离子电池
CN114464884A (zh) * 2022-01-21 2022-05-10 珠海冠宇电池股份有限公司 一种电解液及包括该电解液的含硅基负极的电池
CN115036572A (zh) * 2022-06-21 2022-09-09 深圳新宙邦科技股份有限公司 一种锂二次电池
CN115763973A (zh) * 2022-10-25 2023-03-07 珠海冠宇电池股份有限公司 一种电解液及包括该电解液的电池

Also Published As

Publication number Publication date
CN115763973A (zh) 2023-03-07

Similar Documents

Publication Publication Date Title
CN109216759B (zh) 一种锂离子电池电解液以及锂离子电池
CN109728340B (zh) 锂离子电池
CN114784380A (zh) 一种电解液及其电化学装置和电子装置
CN109428078B (zh) 一种电池
CN112216862A (zh) 一种高镍三元锂离子电池电解液及三元锂离子电池
CN109119599B (zh) 一种二次电池及其制备方法
WO2024099377A1 (zh) 一种电解液及包括该电解液的电池
CN113839095B (zh) 一种电解液及包括该电解液的电池
CN113078356B (zh) 一种高电压钴酸锂锂离子电池非水电解液及锂离子电池
WO2024082979A1 (zh) 一种电解液及包括该电解液的电池
WO2024078357A1 (zh) 一种电解液及包括该电解液的电池
WO2024041150A1 (zh) 一种电解液及包括该电解液的电池
CN109119631B (zh) 一种二次电池
CN110649318A (zh) 一种电解液及其制备方法和锂离子电池
CN116130764A (zh) 一种电解液和电池
WO2022099542A1 (zh) 一种电解液、电化学装置以及电子装置
CN114976247A (zh) 一种电解液和含有该电解液的电池
CN110970659B (zh) 非水电解液及锂离子电池
CN113328144A (zh) 一种锂离子电池电解液及使用该电解液的锂离子电池
CN109309230B (zh) 一种二次电池极片，其制备方法及使用该极片的二次电池
CN112117493B (zh) 一种锂离子电池用电解液及包括该电解液的锂离子电池
CN113948770B (zh) 改善电池高温存储特性的电解液以及锂离子电池
WO2023000255A1 (zh) 一种电解液、锂离子电池和用电装置
CN114024031B (zh) 一种锂离子电池电解液及其锂离子电池
CN114243109B (zh) 一种电解液及包括该电解液的电池

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 23888063

Country of ref document: EP

Kind code of ref document: A1