WO2023109259A1 - 电解液添加剂、电解液以及包含其的锂离子二次电池 - Google Patents

电解液添加剂、电解液以及包含其的锂离子二次电池 Download PDF

Info

Publication number
WO2023109259A1
WO2023109259A1 PCT/CN2022/123523 CN2022123523W WO2023109259A1 WO 2023109259 A1 WO2023109259 A1 WO 2023109259A1 CN 2022123523 W CN2022123523 W CN 2022123523W WO 2023109259 A1 WO2023109259 A1 WO 2023109259A1
Authority
WO
WIPO (PCT)
Prior art keywords
additive
electrolyte
weight
parts
lithium
Prior art date
Application number
PCT/CN2022/123523
Other languages
English (en)
French (fr)
Inventor
朱诚
陈英韬
钟昊悦
薛曼利
张昊
Original Assignee
株式会社村田制作所
朱诚
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 株式会社村田制作所, 朱诚 filed Critical 株式会社村田制作所
Publication of WO2023109259A1 publication Critical patent/WO2023109259A1/zh

Links

Images

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
    • H01M2300/00—Electrolytes
    • H01M2300/0088—Composites
    • H01M2300/0091—Composites in the form of mixtures
    • 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 invention relates to the field of lithium-ion secondary batteries, in particular to an electrolyte additive, an electrolyte and a lithium-ion secondary battery containing the same.
  • Electrolyte is the carrier of ion transmission in lithium-ion batteries, generally composed of organic solvents, functional additives and lithium salts. During the charge and discharge process, the electrolyte will decompose, forming a passivation layer on the surface of the electrode that is electronically insulated but lithium-ion-conducting solid electrolyte interfacial film (SEI film), through which lithium ions can be freely intercalated and extracted. , and at the same time, the passivation layer has solvent repellency so that it can exist stably in the solvent, and solvent molecules cannot pass through the passivation layer, thereby effectively preventing the co-embedding of solvent molecules from damaging the electrode material.
  • SEI film solid electrolyte interfacial film
  • the SEI film formed by electrochemical reaction has strict requirements on the reaction potential, and the introduction of functional additives, especially film-forming additives, is generally considered to be an effective way to improve battery performance.
  • functional additives can participate in the formation of SEI films, and on the other hand, functional The additive can provide a lower reaction potential, making it preferential to the solvent for electrochemical reaction, so as to effectively inhibit the decomposition of the solvent. Even the addition of certain functional additives can protect the functional additives that play a major role, forming a SEI film through multi-stage reactions.
  • the most commonly used functional additives in lithium ion secondary batteries are vinylene carbonate (VC) and fluoroethylene carbonate (fluoroethylene carbonate, FEC) and the like.
  • VC vinylene carbonate
  • FEC fluoroethylene carbonate
  • LUMO lowest unoccupied molecular orbital
  • It is generally considered to be an ideal negative electrode film-forming additive.
  • due to the small atomic radius of fluorine it can improve the solubility of the additive and the wettability between the electrode and the separator, thereby improving the temperature resistance of the battery.
  • FEC is still a carbonate compound in nature, and gas will inevitably be generated during the reaction and decomposition, causing the battery to swell, thereby deteriorating the performance of the battery, especially when FEC is used in large quantities. Therefore, how to solve the problem of swelling and performance degradation of lithium-ion secondary batteries caused by the gas production of carbonate additives such as FEC in the prior art is particularly important.
  • the main purpose of the present invention is to provide an electrolyte additive, an electrolyte comprising the electrolyte additive, and a lithium-ion secondary battery comprising the electrolyte, so as to solve the problems caused by the gas production of carbonate additives such as FEC in the prior art.
  • an electrolyte additive includes a first additive and a second additive, and the first additive has a structure represented by the following formula (1):
  • R and R are each independently selected from fluorine, C 1 to C 3 alkoxy, or phenyl optionally substituted by fluorine, C 1 to C 3 alkyl or C 1 to C 3 perfluoroalkyl ,
  • the second additive is selected from any one of the following substances:
  • R1 and R2 are each independently selected from phenyl groups substituted by C1 to C3 perfluoroalkyl groups.
  • R1 and R2 are each independently selected from phenyl groups substituted by trifluoromethyl.
  • the second additive is
  • the first additive is selected from any of the following substances:
  • the weight ratio of the first additive to the second additive is in the range of 1:3 to 4:3.
  • an electrolyte comprising an organic solvent, a lithium salt, and the electrolyte additive described above.
  • the amount of the first additive is in the range of 0.1 parts by weight to 3.0 parts by weight, preferably the amount of the first additive is in the range of 0.1 parts by weight to 2.0 parts by weight. within the range of parts by weight.
  • the amount of the second additive is in the range of 0.1 parts by weight to 3.0 parts by weight, preferably the amount of the second additive is in the range of 0.1 parts by weight to 2.0 parts by weight within the range of parts by weight.
  • a lithium ion secondary battery comprising: a positive electrode, a negative electrode, a separator, and the electrolyte solution described above.
  • the electrolyte additive of the present invention the electrolyte comprising the electrolyte additive, and the lithium ion secondary battery comprising the electrolyte, the gas generation and expansion of the lithium ion secondary battery are suppressed, the composition of the SEI film is improved, and the The internal resistance of the lithium ion secondary battery is improved and the cycle performance of the lithium ion secondary battery is improved.
  • FIG. 1 shows the high-temperature cycle performance graphs of Example 2 and Comparative Examples 1-3.
  • FIG. 2 shows the impedance spectra of Example 2 and Comparative Examples 1-3 after cycles.
  • a typical embodiment of the present invention provides an electrolyte additive, the electrolyte additive includes a first additive and a second additive, the first additive has the following formula (1): structure:
  • R 1 and R 2 are each independently selected from fluorine, C 1 to C 3 alkoxyl group, or optionally replaced by fluorine, C 1 to C 3 alkyl group or
  • the second additive is selected from any one of the following substances:
  • the present invention uses perfluorocyclopentene compounds as the first additive, and the perfluorocyclopentene compounds use fluorine atoms to replace the oxygen atoms and carbonyl groups in the additives of the prior art.
  • fluorine ions replace CO and / or carbon-based groups such as CO2 , avoiding gas production.
  • the reaction potential of the electrolyte additive can be effectively regulated, thereby regulating the decomposition potential of other functional additives or solvents, which is beneficial to the protection mechanism of additives and solvents.
  • the perfluorinated skeleton structure can effectively improve the wettability and temperature characteristics of the electrolyte.
  • the change of the substituent functional group at the alkenyl position of the first additive can form a multi-stage decomposition reaction and play a synergistic effect.
  • the first additive of the present invention decomposes prior to the solvent on the surface of the negative electrode of the lithium-ion secondary battery to form a solid electrolyte interfacial film (SEI film) to protect the solvent and the electrode, while forming LiF.
  • SEI film solid electrolyte interfacial film
  • LiF can modify the SEI film, thereby improving the lithium ion conductivity and improving the cycle stability of the lithium ion secondary battery.
  • the first additive decomposes, it does not produce carbon-based groups such as CO and/or CO 2 , which can effectively solve the problems of lithium-ion secondary battery expansion and performance degradation caused by gas production of carbonate additives such as FEC in the prior art, and can improve High-temperature performance of lithium-ion secondary batteries.
  • the second additive of the present invention can consume hydrofluoric acid and excess fluorine ions existing in the electrolyte, protect the electrodes of lithium-ion secondary batteries, reduce the internal resistance of lithium-ion secondary batteries, and consume excessive fluorine ions to reduce LiF
  • the content can reduce the thickness of the SEI film and improve the lithium ion conductivity.
  • the inventors of the present invention unexpectedly found after conducting a large number of experiments that a synergistic effect can be produced by the combination of the first additive and the second additive of the present invention.
  • the second An additive decomposes to generate LiF, which can modify the SEI film, thereby improving the cycle stability of the lithium-ion secondary battery.
  • the second additive consumes excessive LiF, which reduces the internal resistance of the lithium-ion secondary battery.
  • the LiF added to the system by the first additive can effectively inhibit the Si-F reaction and inhibit the silicon-based reaction as the second additive. Effect of borates, silyl sulfates, silyl phosphates or silyl phosphites on degradation cycles at high temperatures.
  • the wettability of the electrolyte can be improved, the gas generation and expansion of the lithium-ion secondary battery can be suppressed, the internal resistance of the lithium-ion secondary battery can be reduced, and the cycle characteristics of the lithium-ion secondary battery can be improved. and high temperature performance.
  • the reaction mechanism of the first additive and the second additive is as follows:
  • the first additive is a perfluorocyclopentene compound, which is an unsaturated fluorine-containing compound structure, which can be connected with an electron-donating or electron-withdrawing functional group, which can improve the ring
  • the electrochemical reactivity of the pentene parent structure makes it easy to obtain electrons and form a solid electrolyte interfacial film (SEI film) on the surface of the negative electrode.
  • SEI film solid electrolyte interfacial film
  • the second additive is a silicon-based borate, silicon-based sulfate, silicon-based phosphate or silicon-based phosphite structure.
  • the Si-O bond will be broken to generate CH 3 Si-, which is compatible with Fluoride ions generate F-Si compounds, effectively controlling the concentration of hydrofluoric acid in the electrolyte and the thickness of the SEI film.
  • the first additive and the second additive of the present invention have a good match, and film-forming reaction can occur simultaneously during the first charging and discharging process.
  • the synergistic effect of the first additive and the second additive of the present invention improves the composition of the SEI film, effectively reduces the internal resistance of the lithium ion secondary battery and improves the cycle performance of the lithium ion secondary battery.
  • the present invention provides an electrolyte additive, using the combination of the first additive and the second additive to produce a synergistic effect, the first additive generates the necessary LiF to stabilize the interface of the SEI film when the electrolyte is decomposed, thereby improving the lithium-ion secondary battery high temperature performance.
  • the second additive consumes hydrofluoric acid and excess fluorine ions existing in the electrolyte to reduce the impedance of the lithium ion secondary battery.
  • R 1 and R 2 are each independently selected from phenyl substituted by C 1 to C 3 perfluoroalkyl, preferably, R 1 and R 2 are each independently independently selected from phenyl substituted with trifluoromethyl.
  • the first additive of the present invention can effectively regulate the reaction potential of the electrolyte additive, better film-forming reaction occurs, and can better improve the lithium ion cycle performance of the battery.
  • the first additive in order to better interact with the second additive to form a stable negative electrode protective layer and better improve the cycle performance of lithium-ion secondary batteries, can be selected from the following substances Either of:
  • the second additive in order to better interact with the first additive to form an electrode protection layer with good stability and low resistance and to more effectively reduce the internal resistance of the lithium-ion secondary battery, the second additive can be preferentially choose as
  • the weight ratio of the first additive to the second additive is in the range of 1:3 to 4:3, preferably, in the range of 1:3 to 1:1, most preferably, In the range of 1:2 to 1:1.
  • an electrolyte comprising an organic solvent, a lithium salt, and the electrolyte additive described above. Due to containing the electrolyte additive of the present invention, the electrolyte of the present invention can effectively form a stable SEI film on the surface of the negative electrode during the first charging and discharging process of the battery, thereby inhibiting the decomposition of the solvent. Moreover, the use of the electrolytic solution of the present invention suppresses the gas generation and expansion of the lithium ion secondary battery, effectively reduces the internal resistance of the lithium ion secondary battery and improves the cycle performance of the lithium ion secondary battery.
  • the amount of the first additive in the electrolytic solution of the present invention, based on 100 parts by weight of the organic solvent and lithium salt, is in the range of 0.1 parts by weight to 3.0 parts by weight, preferably, 0.1 parts by weight In the range of parts by weight to 2.0 parts by weight, more preferably, in the range of 0.5 parts by weight to 2.0 parts by weight, further preferably, in the range of 0.5 parts by weight to 1.8 parts by weight, further preferably, in the range of 0.5 parts by weight to 1.5 parts by weight, most preferably, in the range of 0.5 to 1.0 parts by weight.
  • the amount of the first additive in the electrolyte can be in the following ranges: 0.15 parts by weight to 2.5 parts by weight, 0.2 parts by weight to 2.3 parts by weight, 0.25 parts by weight to 2.1 parts by weight Parts by weight, 0.3 to 1.9 parts by weight, 0.35 to 1.7 parts by weight, 0.4 to 1.5 parts by weight, 0.45 to 1.3 parts by weight, 0.5 to 1.1 parts by weight, 0.55 to 0.9 parts by weight , 0.6 to 0.8 parts by weight, 0.12 to 0.95 parts by weight, 0.14 to 0.75 parts by weight, 0.16 to 0.55 parts by weight or 0.18 to 0.45 parts by weight.
  • the amount of the second additive in the electrolytic solution of the present invention, based on 100 parts by weight of the organic solvent and lithium salt, is in the range of 0.1 parts by weight to 3.0 parts by weight, preferably, 0.1 parts by weight In the range of parts by weight to 2.0 parts by weight, more preferably, in the range of 0.5 parts by weight to 2.0 parts by weight, further preferably, in the range of 0.5 parts by weight to 1.8 parts by weight, further preferably, in the range of 0.5 parts by weight to 1.5 parts by weight, most preferably, in the range of 1.0 to 1.5 parts by weight.
  • the amount of the second additive in the electrolyte can be in the following ranges: 0.15 parts by weight to 2.5 parts by weight, 0.2 parts by weight to 2.3 parts by weight, 0.25 parts by weight to 2.1 parts by weight Parts by weight, 0.3 to 1.9 parts by weight, 0.35 to 1.7 parts by weight, 0.4 to 1.5 parts by weight, 0.45 to 1.3 parts by weight, 0.5 to 1.1 parts by weight, 0.55 to 0.9 parts by weight , 0.6 to 0.8 parts by weight, 0.12 to 0.95 parts by weight, 0.14 to 0.75 parts by weight, 0.16 to 0.55 parts by weight or 0.18 to 0.45 parts by weight.
  • the organic solvent may be any organic solvent hitherto used in electrolytic solutions.
  • organic solvents include, but are not limited to: straight chain carbonates or cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate , dipropyl carbonate, fluoroethylene carbonate; ethers, such as 1,2-dimethoxyethane, 1,2-diethoxyethane, ⁇ -butyrolactone, tetrahydrofuran, 2-methyl Tetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, diethyl ether; sulfones, such as sulfolane, methyl sulfolane; nitriles, such as acetonitrile, propionitrile, acrylonitrile ; Esters, such as acetate, propionate, butyrate, etc.
  • organic solvents may be used alone or in combination of a plurality of organic solvents.
  • preferred organic solvents include ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate and One or more of dipropyl carbonate.
  • at least one carbonate is used as organic solvent for the electrolyte solution of the invention.
  • at least one linear carbonate and at least one cyclic carbonate are used together as the organic solvent of the electrolyte solution of the present invention.
  • the present invention has no special limitation on the lithium salt contained in the electrolyte, and those lithium salts known to be used in the electrolyte of lithium batteries in the prior art can be used.
  • lithium salts may include: LiCl, LiBr, LiPF 6 , LiBF 4 , LiAsF 6 , LiClO 4 , LiB(C 6 H 5 ) 4 , LiCH 3 SO 3 , LiCF 3 SO 3 , LiN(SO 2 F) 2 , One or more of LiN(CF 3 SO 2 ) 2 , LiC(CF 3 SO 2 ) 3 , LiAlCl 4 and Li 2 SiF 6 .
  • a lithium ion secondary battery comprising: a positive electrode, a negative electrode, a separator, and the electrolyte solution described above. Since the lithium ion secondary battery of the present invention uses the electrolyte solution described above, the lithium ion secondary battery has reduced internal resistance and improved cycle performance.
  • the positive electrode of the present invention includes a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material.
  • a positive electrode active material layer is formed on both surfaces of the positive electrode collector.
  • a metal foil such as aluminum foil, nickel foil, or stainless steel foil can be used as the positive electrode collector.
  • the positive electrode active material layer contains one or more positive electrode materials capable of intercalating and extracting lithium ions as the positive electrode active material, and may contain other materials such as positive electrode binder and/or positive electrode conductor if necessary.
  • the positive electrode material is a lithium-containing compound.
  • lithium-containing compounds include lithium-transition metal composite oxides, lithium-transition metal phosphate compounds, and the like.
  • Lithium-transition metal composite oxides are oxides containing Li and one or more transition metal elements as constituent elements, and lithium-transition metal phosphate compounds contain Li and one or more transition metal elements as constituent elements. Phosphate compounds of constituent elements.
  • the transition metal element is advantageously one or more of Co, Ni, Mn, Fe and the like.
  • lithium-transition metal composite oxides may include, for example, LiCoO 2 and LiNiO 2 and the like.
  • lithium-transition metal phosphate compounds may include, for example, LiFePO 4 and LiFe 1-u Mn u PO 4 (0 ⁇ u ⁇ 1) and the like.
  • the negative electrode of the present invention includes a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material. Negative electrode active material layers are formed on both surfaces of the negative electrode collector.
  • a metal foil such as copper (Cu) foil, nickel foil, or stainless steel foil can be used as the negative electrode collector.
  • the negative electrode active material layer contains one or more negative electrode materials capable of intercalating and extracting lithium ions as the negative electrode active material, and may contain other materials, such as negative electrode binder and/or negative electrode conductive agent, if necessary.
  • the negative electrode active material can be selected from one or more of lithium metal, lithium alloy, carbon material, silicon or tin and oxides thereof.
  • the separator of the present invention is used to separate positive and negative electrodes in batteries and to pass lithium ions therethrough while preventing current short circuit due to contact between the positive and negative electrodes.
  • the separator is, for example, a porous film formed of synthetic resin or ceramics, and may be a laminated film in which two or more porous films are laminated.
  • synthetic resins include, for example, polytetrafluoroethylene, polypropylene, polyethylene, and the like.
  • lithium ions when a lithium ion secondary battery is charged, for example, lithium ions are extracted from a positive electrode and inserted into a negative electrode through an electrolytic solution impregnated in a separator.
  • lithium ions When the lithium ion secondary battery is discharged, for example, lithium ions are extracted from the negative electrode and intercalated into the positive electrode through the electrolytic solution impregnated in the separator.
  • Assemble CR2016 coin cells in a dry laboratory The positive electrode sheet prepared in the above steps was used as the positive electrode, the negative electrode sheet was used as the negative electrode, and the electrolyte prepared in Example 1 was used as the electrolyte. Assemble the positive electrode, negative electrode, separator, and battery case of the coin cell. After the battery is assembled, it is allowed to stand for 24 hours for aging to obtain a button battery.
  • Adopt the method identical with embodiment 1 to prepare button battery difference is: the ethylene carbonate of 20g, the dimethyl carbonate of 62g are mixed with the lithium hexafluorophosphate of 18g to prepare basic electrolytic solution, and electrolytic solution adds 1.0g by formula ( The first additive represented by 1-1) and 1.0 g of the second additive represented by TMSB were stirred evenly, and then added into the battery to prepare a CR2016 button battery.
  • Adopt the method identical with embodiment 1 to prepare button battery difference is: the ethylene carbonate of 20g, the dimethyl carbonate of 62g are mixed with the lithium hexafluorophosphate of 18g to prepare basic electrolytic solution, and electrolytic solution adds 0.5g by formula ( The first additive represented by 1-1) and 1.5 g of the second additive represented by TMSB were stirred evenly, and then added into the battery to prepare a CR2016 button battery.
  • Adopt the method identical with embodiment 1 to prepare button battery difference is: the ethylene carbonate of 20g, the dimethyl carbonate of 62g are mixed with the lithium hexafluorophosphate of 18g to prepare basic electrolyte, electrolyte adds 2.0g by formula ( The first additive represented by 1-1) and 1.5 g of the second additive represented by TMSB were stirred evenly, and then added into the battery to prepare a CR2016 button battery.
  • Adopt the method identical with embodiment 1 to prepare button cell difference is: the ethylene carbonate of 20g, the dimethyl carbonate of 62g are mixed with the lithium hexafluorophosphate of 18g to prepare basic electrolytic solution, and electrolytic solution adds 3.0g by formula ( The first additive represented by 1-1) and 3.0 g of the second additive represented by TMSB were stirred evenly, and then added into the battery to prepare a CR2016 button battery.
  • Adopt the method identical with embodiment 1 to prepare button battery difference is: the ethylene carbonate of 20g, the dimethyl carbonate of 62g are mixed with the lithium hexafluorophosphate of 18g to prepare basic electrolytic solution, and electrolytic solution adds 1.0g by formula ( After the first additive represented by 1-2) and 1.0 g of the second additive represented by TMSP were stirred evenly, they were added into the battery to prepare a CR2016 button battery.
  • Adopt the method identical with embodiment 1 to prepare button battery difference is: the ethylene carbonate of 20g, the dimethyl carbonate of 62g are mixed with the lithium hexafluorophosphate of 18g to prepare basic electrolyte, electrolyte adds 2.0g by formula ( The first additive represented by 1-2) and 1.5 g of the second additive represented by TMSP were stirred evenly, and then added into the battery to prepare a CR2016 button battery.
  • Adopt the method identical with embodiment 1 to prepare button cell difference is: the ethylene carbonate of 20g, the dimethyl carbonate of 62g are mixed with the lithium hexafluorophosphate of 18g to prepare basic electrolytic solution, and electrolytic solution adds 3.0g by formula ( The first additive represented by 1-2) and 3.0 g of the second additive represented by TMSP were stirred evenly, and then added into the battery to prepare a CR2016 button battery.
  • Adopt the method identical with embodiment 1 to prepare button battery difference is: the ethylene carbonate of 20g, the dimethyl carbonate of 62g are mixed with the lithium hexafluorophosphate of 18g to prepare basic electrolytic solution, and electrolytic solution adds 1.0g by formula ( The first additive represented by 1-1) and 1.0 g of the second additive represented by TMSP were stirred evenly, and then added into the battery to prepare a CR2016 button battery.
  • Adopt the method identical with embodiment 1 to prepare button battery difference is: the ethylene carbonate of 20g, the dimethyl carbonate of 62g are mixed with the lithium hexafluorophosphate of 18g to prepare basic electrolytic solution, and electrolytic solution adds 1.0g by formula ( The first additive represented by 1-2) and 1.0 g of the second additive represented by TMSB were stirred evenly, and then added into the battery to prepare a CR2016 button battery.
  • a button battery was prepared in the same manner as in Example 1, except that 20 g of ethylene carbonate, 62 g of dimethyl carbonate, and 18 g of lithium hexafluorophosphate were mixed to prepare a basic electrolyte, which was added to the battery to prepare a CR2016 button battery .
  • Adopt the method identical with embodiment 1 to prepare button battery difference is: the ethylene carbonate of 20g, the dimethyl carbonate of 62g are mixed with the lithium hexafluorophosphate of 18g to prepare basic electrolyte, electrolyte adds 2.0g by formula ( After the first additive represented by 1-1) was stirred evenly, it was added into the battery to prepare a CR2016 button battery.
  • the button cell is prepared in the same manner as in Example 1, except that 20 g of ethylene carbonate, 62 g of dimethyl carbonate and 18 g of lithium hexafluorophosphate are mixed to prepare a basic electrolyte, and 2.0 g of the electrolyte is added and represented by TMSB After the second additive was stirred evenly, it was added into the battery to prepare a CR2016 button battery.
  • Adopt the method identical with embodiment 1 to prepare button battery difference is: the ethylene carbonate of 20g, the dimethyl carbonate of 62g are mixed with the lithium hexafluorophosphate of 18g to prepare basic electrolyte, electrolyte adds 2.0g by formula ( After the first additive indicated in 1-2) was stirred evenly, it was added into the battery to prepare a CR2016 button battery.
  • first additive amount and “second additive amount” are both percentages by weight based on the total weight of the basic electrolyte.
  • Example 2 By comparing the results of Example 2 and Comparative Example 2, it can be seen that compared with Comparative Example 2 in which only the first additive is added, the battery in Example 2 in which the electrolyte additive includes a combination of the first additive and the second additive has Higher cycle retention and lower post-cycle impedance.
  • Comparative Example 3 By comparing the results of Example 2 and Comparative Example 3, it can be seen that compared with Comparative Example 3 in which only the second additive is added, the battery in Example 2 in which the electrolyte additive includes a combination of the first additive and the second additive has Significantly higher cycle retention and slightly higher post-cycle impedance.
  • Example 2 By comparing the results of Example 2 with Comparative Example 1, it can be seen that, compared with Comparative Example 1 without adding any electrolyte additive, the battery in Example 2 in which the electrolyte additive includes a combination of the first additive and the second additive It has higher cycle retention and lower post-cycle impedance.
  • Example 6 By comparing the results of Example 6 and Comparative Example 4, it can be seen that compared with Comparative Example 4 in which only the first additive is added, the battery in Example 6 in which the electrolyte additive includes a combination of the first additive and the second additive has Higher cycle retention and lower post-cycle impedance.
  • Comparative Example 1 By comparing the results of Example 6 with Comparative Example 1, it can be seen that, compared with Comparative Example 1 without adding any electrolyte additive, the battery in Example 6 in which the electrolyte additive includes a combination of the first additive and the second additive It has higher cycle retention and slightly higher post-cycle impedance.
  • the electrolyte additive includes the combination of the first additive and the second additive in Example 1- 10 can ensure that the battery has a higher cycle retention rate under the condition that the impedance decreases or does not increase significantly after the cycle.
  • the electrolyte additives include the first additive and the second additive.
  • the batteries in the combination of Examples 2-4 and Example 10 have higher cycle retention and lower post-cycle impedance. It can be seen that, compared with Comparative Example 1, Examples 2-4 and Example 10, in which the electrolyte additive includes a combination of the first additive and the second additive, have better effects on both the cycle retention rate and the post-cycle impedance. Optimized.
  • Examples 2-4 and Example 9 By comparing the results of Examples 2-4 and Example 9 with Comparative Example 2, it can be seen that compared with Comparative Example 2 where only the first additive is added, the implementation of the combination of the first additive and the second additive in the electrolyte additive The batteries in Examples 2-4 and Example 9 had higher cycle retention and lower post-cycle impedance. It can be seen that, compared with Comparative Example 2, Examples 2-4 and Example 9, in which the electrolyte additive includes a combination of the first additive and the second additive, not only reduce the impedance after cycle, but also achieve a higher cycle retention rate. further improvement.
  • the electrolyte additive includes the combination of the first additive and the second additive in Examples 1-5
  • the battery in 2009 has greatly improved the cycle retention while maintaining a low post-cycle impedance.
  • the electrolyte additive includes a combination of the first additive and the second additive
  • the embodiment 6, embodiment 7 and embodiment 10 not only reduce the impedance after cycle, but also realize the further improvement of the cycle retention rate.
  • the present invention utilizes the combination of the first additive and the second additive to produce a synergistic effect, so that in the cycle of the battery A better balance was obtained between retention and post-cycle impedance.
  • the present invention through the combination of two kinds of additives, exhibits excellent effects on the cycle retention rate of the battery and the impedance after cycle, therefore, the electrolyte additive of the present invention effectively reduces lithium
  • the internal resistance of the ion secondary battery is improved and the cycle performance of the lithium ion secondary battery is improved.

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

本发明提供了电解液添加剂、电解液以及包含其的锂离子二次电池。电解液添加剂包括第一添加剂和第二添加剂，第一添加剂具有由以下式(1)所示的结构，其中，R1和R2各自独立地选自氟，C1至C3烷氧基，或者可选被氟、C1至C3烷基或C1至C3全氟烷基取代的苯基，第二添加剂选自以下物质中的任一种：式(2)、式(3)、式(4)或者式(5)。通过本发明的电解液添加剂、包含该电解液添加剂的电解液以及包括该电解液的锂离子二次电池，抑制了锂离子二次电池的产气膨胀，改善了SEI膜的构成，有效降低锂离子二次电池的内阻并且提高了锂离子二次电池的循环性能。

Description

电解液添加剂、电解液以及包含其的锂离子二次电池 技术领域
本发明涉及锂离子二次电池领域，具体而言，涉及电解液添加剂、电解液以及包含其的锂离子二次电池。
背景技术
近年来，随着电子技术的不断发展，人们对用于支持电子设备的能源供应的电池装置的需求也在不断增加。现如今，需要能够存储更多电量且能够输出高功率的电池。传统铅酸电池以及镍氢电池等已经不能满足诸如智能手机的移动设备、和诸如蓄电系统等固定设备的新型电子制品的需求。因此，锂离子电池引起了人们的广泛关注。在对锂离子电池的开发过程中，已经较为有效地提高了其容量和性能。
电解液是锂离子电池中离子传递的载体，一般由有机溶剂、功能添加剂和锂盐组成。在充放电过程中，电解液会发生分解，在电极表面形成一层电子绝缘但锂离子导通的固体电解质界面膜(SEI膜)钝化层，锂离子可以经过该钝化层自由嵌入和脱出，同时该钝化层具有疏溶剂性从而可以在溶剂中稳定存在，溶剂分子不能通过该钝化层，从而有效防止了溶剂分子的共嵌对电极材料的破坏。因此，SEI膜的形成对锂离子电池的性能至关重要。成膜稳定、厚度均匀并且锂离子导通良好的SEI膜可以显著提高锂离子电池的可逆容量，延长锂离子电池的寿命。经电化学反应形成的SEI膜对反应电位要求严格，而功能性添加剂特别是成膜添加剂的引入一般认为是改善电池性能的有效方法，一方面功能性添加剂可以参与SEI膜的形成，另外功能性添加剂可提供更低的反应电位，使其优先于溶剂发生电化学反应，以有效抑制溶剂的分解。甚至某些功能性添加剂的加入可以保护起主要作用的功能添加剂，形成经多级反应的SEI膜。
在现有技术中，在锂离子二次电池中最常使用的功能性添加剂是碳酸亚乙烯酯(VC)和氟代碳酸亚乙酯(氟代碳酸乙烯酯，FEC)等。因FEC引入氟元素后，最低未占分子轨道(LUMO)能量较低，易被还原，通常认为其是比较理想的负极成膜添加剂。同时，氟元素因原子半径很小，可以提高添加剂的溶解性以及电极与隔膜之间的浸润性，从而提高电池的耐温特性。但是，FEC本质上仍属于碳酸酯类化合物，在反应分解时会不可避免地产生气体，造成电池膨胀，从而劣化了电池的性能，尤其在FEC大量使用时该现象更为严重。因此，如何解决现有技术中FEC等碳酸酯类添加剂的产气导致锂离子二次电池膨胀和性能劣化的问题显得尤为重要。
发明内容
本发明的主要目的在于提供一种电解液添加剂、包含该电解液添加剂的电解液以及包括该电解液的锂离子二次电池，以解决现有技术中FEC等碳酸酯类添加剂的产气导致锂离子二次电池膨胀和性能劣化的问题。
为了实现上述目的，根据本发明的一个方面，提供了一种电解液添加剂，该电解液添加剂包括第一添加剂和第二添加剂，该第一添加剂具有由以下式(1)所示的结构：
Figure PCTCN2022123523-appb-000001
其中，R 1和R 2各自独立地选自氟，C 1至C 3烷氧基，或者可选被氟、C 1至C 3烷基或C 1至C 3全氟烷基取代的苯基，
该第二添加剂选自以下物质中的任一种：
Figure PCTCN2022123523-appb-000002
或者
Figure PCTCN2022123523-appb-000003
进一步地，在上述电解液添加剂中，R 1和R 2各自独立地选自被C 1至C 3全氟烷基取代的苯基。
进一步地，在上述电解液添加剂中，R 1和R 2各自独立地选自被三氟甲基取代的苯基。
进一步地，在上述电解液添加剂中，该第二添加剂为
Figure PCTCN2022123523-appb-000004
进一步地，在上述电解液添加剂中，该第一添加剂选自以下物质中的任一种：
Figure PCTCN2022123523-appb-000005
Figure PCTCN2022123523-appb-000006
或者
Figure PCTCN2022123523-appb-000007
进一步地，在上述电解液添加剂中，该第一添加剂与该第二添加剂的重量比在1:3至4:3的范围内。
根据本发明的另一个方面，提供了一种电解液，包含有机溶剂、锂盐以及前文描述的电解液添加剂。
进一步地，在上述电解液中，基于100重量份的有机溶剂与锂盐，第一添加剂的量在0.1重量份至3.0重量份的范围内，优选地第一添加剂的量在0.1重量份至2.0重量份的范围内。
进一步地，在上述电解液中，基于100重量份的有机溶剂与锂盐，第二添加剂的量在0.1重量份至3.0重量份的范围内，优选地第二添加剂的量在0.1重量份至2.0重量份的范围内。
根据本发明的又一个方面，提供了一种锂离子二次电池，包括：正极、负极、隔膜、以及前文描述的电解液。
通过本发明的电解液添加剂、包含该电解液添加剂的电解液以及包括该电解液的锂离子二次电池，抑制了锂离子二次电池的产气膨胀，改善了SEI膜的构成，有效降低了锂离子二次电池的内阻并且提高了锂离子二次电池的循环性能。
附图说明
图1示出了实施例2和比较例1-3的高温循环性能图谱。
图2示出了实施例2和比较例1-3的循环后阻抗图谱。
具体实施方式
需要说明的是，在不冲突的情况下，本申请中的各个实施例及各实施例中的特征可以相互组合。下面将结合实施例来详细说明本发明。以下的实施例仅为示例性的，并不用来构成对于本发明保护范围的限制。
如背景技术中所说明的，现有技术中的锂离子二次电池中通常使用氟代碳酸亚乙酯(FEC)等作为负极成膜添加剂。然而，在使用FEC等碳酸酯类添加剂时会出现产气导致锂离子二次电池膨胀和性能劣化的问题。针对现有技术中的问题，本发明的一个典型的实施方式提供了一种电解液添加剂，该电解液添加剂包括第一添加剂和第二添加剂，第一添加剂具有由以下式(1)所示的结构：
Figure PCTCN2022123523-appb-000008
其中，R 1和R 2各自独立地选自氟，C 1至C 3烷氧基，或者可选被氟、C 1至C 3烷基或
C 1至C 3全氟烷基取代的苯基，
第二添加剂选自以下物质中的任一种：
Figure PCTCN2022123523-appb-000009
本发明采用全氟环戊烯类化合物作为第一添加剂，该全氟环戊烯类化合物采用氟原子代替了现有技术添加剂中的氧原子与羰基，该添加剂分解时以氟离子代替了CO和/或CO 2等碳基基团，避免了产气。同时，通过改变烯基位置取代基的官能团，可以有效调控电解液添加剂的反应电位，从而调控其他功能性添加剂或溶剂的分解电位，这有利于添加剂与溶剂的保护机制。同时，可以有效抑制锂离子二次电池的产气膨胀并且提高锂离子二次电池的安全特性。全氟骨架结构的引入可以有效提高电解液的浸润性与温度特性。另外，第一添加剂的烯基位置取代基官能团的改变，可以形成多级分解反应，起到协同作用。
本发明的第一添加剂优先于溶剂在锂离子二次电池负极的表面分解形成固体电解质界面膜(SEI膜)以保护溶剂与电极，同时形成LiF。LiF作为SEI膜中重要的无机盐成分可以改性SEI膜，从而可以提高锂离子电导率，并且可以改善锂离子二次电池的循环稳定性。第一添加剂分解时不产生CO和/或CO 2等碳基基团，可以有效解决现有技术中FEC等碳酸酯类添加剂产气导致锂离子二次电池膨胀和性能劣化的问题，并且可以改善锂离子二次电池的高温性能。
本发明的第二添加剂可以消耗电解液内存在的氢氟酸与过量的氟离子，保护锂离子二次电池的电极，降低锂离子二次电池的内阻，同时消耗过量的氟离子以减少LiF的含量，可以减薄SEI膜的厚度进而提高锂离子电导率。
本发明的发明人在进行了大量的实验之后出乎意料地发现，通过本发明的第一添加剂和第二添加剂的组合可以产生协同作用。具体地，利用作为第一添加剂的全氟环戊烯类化合物与作为第二添加剂的硅基硼酸酯、硅基硫酸酯、硅基磷酸酯或硅基亚磷酸酯的组合，一方面，第一添加剂分解产生LiF，可以改性SEI膜，进而改善锂离子二次电池的循环稳定性。另一方面，第二添加剂消耗过量的LiF，降低了锂离子二次电池的内阻，而且，第一添加剂向体系内补充的LiF可以有效抑制Si-F反应，抑制作为第二添加剂的硅基硼酸酯、硅基硫酸酯、硅基磷酸酯或硅基亚磷酸酯在高温时劣化循环的影响。通过第一添加剂和第二添加剂的组合可以提高电解液的浸润性，抑制锂离子二次电池的产气膨胀，降低了锂离子二次电池的内阻，改善了锂离子二次电池的循环特性和高温性能。
第一添加剂和第二添加剂的反应机理如下：第一添加剂为全氟环戊烯类化合物，为不饱和含氟化合物结构，其可以连接带有供电子性或者吸电子性的官能团，能够提高环戊烯母体结构的电化学反应性，使其易得电子而在负极表面上形成固体电解质界面膜(SEI膜)。同时，第二添加剂为硅基硼酸酯、硅基硫酸酯、硅基磷酸酯或硅基亚磷酸酯结构，第二添加剂在得电子后Si-O键会断裂生成CH 3Si-，其与氟离子作用生成F-Si化合物，有效控制电解液中存在的氢氟酸的浓度以及SEI膜的厚度。本发明的第一添加剂和第二添加剂具有很好的匹配性，可以在首次充放电过程中同时发生成膜反应。本发明的第一添加剂和第二添加剂发生协同作用，改善了SEI膜的构成，有效降低了锂离子二次电池的内阻并且提高了锂离子二次电池的循环性能。
本发明提供了一种电解液添加剂，利用第一添加剂和第二添加剂的组合产生协同效应，第一添加剂在电解液分解时生成必要的LiF以稳定SEI膜的界面，从而改善锂离子二次电池的高温性能。第二添加剂消耗在电解液内存在的氢氟酸与过量的氟离子以降低锂离子二次电池的阻抗。
在本发明的一些实施方式中，在式(1)中，R 1和R 2各自独立地选自被C 1至C 3全氟烷基取代的苯基，优选地，R 1和R 2各自独立地选自被三氟甲基取代的苯基。当R 1和R 2各自独立地选自上述基团时，本发明的第一添加剂可以有效地调控电解液添加剂的反应电位，更好地发生成膜反应，并且可以更好地提高锂离子二次电池的循环性能。
在本发明的一些实施方式中，为了更好地与第二添加剂相互作用形成稳定性好的负极保护层并且更好地提高锂离子二次电池的循环性能，第一添加剂可以选自以下物质中的任一种：
Figure PCTCN2022123523-appb-000010
Figure PCTCN2022123523-appb-000011
Figure PCTCN2022123523-appb-000012
或者
Figure PCTCN2022123523-appb-000013
在本发明的一些实施方式中，为了更好地与第一添加剂相互作用形成稳定性好且阻抗较小的电极保护层并且更有效地降低锂离子二次电池的内阻，第二添加剂可以优先选择为
Figure PCTCN2022123523-appb-000014
在本发明的一些实施方式中，第一添加剂与第二添加剂的重量比在1:3至4:3的范围内，优选地，在1:3至1:1的范围内，最优选地，在1:2至1:1的范围内。通过将第一添加剂与第二添加剂的重量比控制在上述范围内，可以进一步提高电解液的浸润性，进一步降低锂离子二次电池的内阻，并且进一步改善锂离子二次电池的循环特性和高温性能。
在本发明的另一个典型的实施方式中，提供了一种电解液，包含有机溶剂、锂盐以及前文描述的电解液添加剂。由于包含了本发明的电解液添加剂，因此，本发明的电解液在电池首次充放电过程中能够有效地在负极的表面上形成稳定的SEI膜，从而抑制溶剂的分解。而且，利用本发明的电解液抑制了锂离子二次电池的产气膨胀，有效降低了锂离子二次电池的内阻并且提高了锂离子二次电池的循环性能。
在本发明的一些实施方式中，在本发明的电解液中，基于100重量份的有机溶剂与锂盐，第一添加剂的量在0.1重量份至3.0重量份的范围内，优选地，在0.1重量份至2.0重量份的 范围内，更优选地，在0.5重量份至2.0重量份的范围内，进一步优选地，在0.5重量份至1.8重量份的范围内，进一步优选地，在0.5重量份至1.5重量份的范围内，最优选地，在0.5重量份至1.0重量份的范围内。通过将第一添加剂的量控制在上述范围内，可以更好地改善锂离子二次电池的循环特性和高温性能。
具体而言，基于100重量份的有机溶剂与锂盐，电解液中第一添加剂的量可以在以下范围内：0.15重量份至2.5重量份、0.2重量份至2.3重量份、0.25重量份至2.1重量份、0.3重量份至1.9重量份、0.35重量份至1.7重量份、0.4重量份至1.5重量份、0.45重量份至1.3重量份、0.5重量份至1.1重量份、0.55重量份至0.9重量份、0.6重量份至0.8重量份、0.12重量份至0.95重量份、0.14重量份至0.75重量份、0.16重量份至0.55重量份或者0.18重量份至0.45重量份。
在本发明的一些实施方式中，在本发明的电解液中，基于100重量份的有机溶剂与锂盐，第二添加剂的量在0.1重量份至3.0重量份的范围内，优选地，在0.1重量份至2.0重量份的范围内，更优选地，在0.5重量份至2.0重量份的范围内，进一步优选地，在0.5重量份至1.8重量份的范围内，进一步优选地，在0.5重量份至1.5重量份的范围内，最优选地，在1.0重量份至1.5重量份的范围内。通过将第二添加剂的量控制在上述范围内，可以更好地降低锂离子二次电池的内阻。
具体而言，基于100重量份的有机溶剂与锂盐，电解液中第二添加剂的量可以在以下范围内：0.15重量份至2.5重量份、0.2重量份至2.3重量份、0.25重量份至2.1重量份、0.3重量份至1.9重量份、0.35重量份至1.7重量份、0.4重量份至1.5重量份、0.45重量份至1.3重量份、0.5重量份至1.1重量份、0.55重量份至0.9重量份、0.6重量份至0.8重量份、0.12重量份至0.95重量份、0.14重量份至0.75重量份、0.16重量份至0.55重量份或者0.18重量份至0.45重量份。
在本发明中，有机溶剂可以是迄今为止用于电解液中的任何有机溶剂。有机溶剂的实例包括但不限于：直链碳酸酯类或环状碳酸酯类，如碳酸亚乙酯、碳酸亚丙酯、碳酸亚丁酯、碳酸二乙酯、碳酸二甲酯、碳酸甲乙酯、碳酸二丙酯、氟代碳酸亚乙酯；醚类，如1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、γ-丁内酯、四氢呋喃、2-甲基四氢呋喃、1,3-二氧戊环、4-甲基-1,3-二氧戊环、二乙醚；砜类，如环丁砜、甲基环丁砜；腈类，如乙腈、丙腈、丙烯腈；酯类，如乙酸酯、丙酸酯、丁酸酯等。可以单独使用这些有机溶剂或组合使用多种有机溶剂。在本发明的一些实施方式中，优选的有机溶剂包括碳酸亚乙酯、碳酸亚丙酯、碳酸亚丁酯、氟代碳酸亚乙酯、碳酸二乙酯、碳酸二甲酯、碳酸甲乙酯和碳酸二丙酯中的一种或多种。在一个优选的实施方式中，使用至少一种碳酸酯作为本发明电解液的有机溶剂。在一个优选的实施方式中，使用至少一种直链碳酸酯和至少一种环状碳酸酯共同作为本发明电解液的有机溶剂。
本发明对电解液中所包含的锂盐没有特殊限制，现有技术中已知可用于锂电池电解液的那些锂盐都可以被采用。锂盐的实例可以包括：LiCl、LiBr、LiPF 6、LiBF 4、LiAsF 6、LiClO 4、LiB(C 6H 5) 4、LiCH 3SO 3、LiCF 3SO 3、LiN(SO 2F) 2、LiN(CF 3SO 2) 2、LiC(CF 3SO 2) 3、LiAlCl 4和Li 2SiF 6中的一种或多种。
在本发明的另一个典型的实施方式中，提供了一种锂离子二次电池，包括：正极、负极、隔膜、以及前文描述的电解液。由于本发明的锂离子二次电池使用了前文描述的电解液，因此，该锂离子二次电池具有降低的内阻和改善的循环性能。
本发明的正极包括正极集电体和含有正极活性物质的正极活性物质层。在正极集电体的两个表面上形成正极活性物质层。可使用诸如铝箔、镍箔或不锈钢箔的金属箔作为正极集电体。
正极活性物质层含有能够嵌入和脱出锂离子的一种或多种正极材料作为正极活性物质，必要时可以含有另外的材料，例如正极粘结剂和/或正极导电剂。
优选地，正极材料是含锂化合物。这种含锂化合物的实例包括锂-过渡金属复合氧化物、锂-过渡金属磷酸盐化合物等等。锂-过渡金属复合氧化物是含有Li和一种或两种以上的过渡金属元素作为组成元素的氧化物，锂-过渡金属磷酸盐化合物是含有Li和一种或两种以上的过渡金属元素作为组成元素的磷酸盐化合物。过渡金属元素有利地是Co、Ni、Mn和Fe等中的一种或多种。
锂-过渡金属复合氧化物的实例可以包括例如LiCoO 2和LiNiO 2等。锂-过渡金属磷酸盐化合物的实例可以包括例如LiFePO 4和LiFe 1-uMn uPO 4(0<u<1)等。
本发明的负极包括负极集电体和含有负极活性物质的负极活性物质层。在负极集电体的两个表面上形成负极活性物质层。可使用诸如铜(Cu)箔、镍箔或不锈钢箔的金属箔作为负极集电体。
负极活性物质层含有能够嵌入和脱出锂离子的一种或多种负极材料作为负极活性物质，必要时可以含有另外的材料，例如负极粘结剂和/或负极导电剂。
负极活性物质可以选自锂金属、锂合金、碳材料、硅或锡及其氧化物中的一种或多种。
本发明的隔膜用于将电池中的正极和负极分开，并且使锂离子从中通过，同时防止由于正极和负极之间的接触所造成的电流短路。隔膜例如是由合成树脂或陶瓷形成的多孔膜，并且可以是其中将两个或更多个多孔膜层压的层压膜。合成树脂的实例包括例如聚四氟乙烯、聚丙烯和聚乙烯等。
在本发明的实施方式中，当对锂离子二次电池进行充电时，例如，锂离子从正极脱出并且通过浸渍在隔膜中的电解液嵌入负极中。当对锂离子二次电池进行放电时，例如，锂离子从负极脱出并且通过浸渍在隔膜中的电解液嵌入正极中。
以下结合具体实施例对本申请作进一步详细描述，这些实施例不能理解为限制本申请所要求保护的范围。
实施例
实施例1
正极的制备
将95.5g的镍钴酸锂正极活性物质、2.5g的导电炭黑和1.9g的聚偏氟乙烯和0.1g的聚乙烯吡咯烷酮分散剂混合以获得正极混合物，并将所获得的混合物分散在N-甲基吡咯烷酮中以获得正极混合物浆料。随后，将获得的正极混合物浆料均匀地涂布到铝箔上以获得正极活性材料层，对正极活性材料层进行干燥，并利用冲压成型工艺形成正极极片。
负极的制备
将95.85g的氧化亚硅(SiO x，1<x<2)与石墨粉末混合物、1.0g的Super P导电剂、3.15g的CMC(羧甲基纤维素钠)粘结剂和SBR(丁苯橡胶)和适当量的水进行搅拌以制备负极混合物浆料。然后将获得的负极混合物浆料均匀地涂布到铜箔上以获得负极活性材料层，对负极活性材料层进行干燥，并利用冲压成型工艺形成负极极片。
电解液的制备
将20g的碳酸亚乙酯、62g的碳酸二甲酯与18g的六氟磷酸锂混合以制备基础电解液。电解液添加0.1g由式(1-1)表示的第一添加剂和0.1g由TMSB表示的第二添加剂搅拌均匀，添加到电池内制备CR2016纽扣电池。
Figure PCTCN2022123523-appb-000015
式(1-1)(1,2-二(2,4-二(三氟甲基)苯基)-3,3,4,4,5,5-六氟-环戊烯-1)
Figure PCTCN2022123523-appb-000016
TMSB(硼酸三(三甲基硅基)酯)
电池的组装
在干燥实验室内组装CR2016扣式电池。将上述步骤制作得到的正极极片作为正电极，负极极片作为负电极，并将实施例1中制备的电解液作为电解液。将正电极、负电极、隔膜与扣式电池的电池壳组装。电池组装完毕后，静置24h陈化，从而得到纽扣电池。
实施例2
采用与实施例1相同的方法制备纽扣电池，不同之处在于：将20g的碳酸亚乙酯、62g的碳酸二甲酯与18g的六氟磷酸锂混合以制备基础电解液，电解液添加1.0g由式(1-1)表示的第一添加剂和1.0g由TMSB表示的第二添加剂搅拌均匀后，添加到电池内制备CR2016纽扣电池。
实施例3
采用与实施例1相同的方法制备纽扣电池，不同之处在于：将20g的碳酸亚乙酯、62g的碳酸二甲酯与18g的六氟磷酸锂混合以制备基础电解液，电解液添加0.5g由式(1-1)表示的第一添加剂和1.5g由TMSB表示的第二添加剂搅拌均匀后，添加到电池内制备CR2016纽扣电池。
实施例4
采用与实施例1相同的方法制备纽扣电池，不同之处在于：将20g的碳酸亚乙酯、62g的碳酸二甲酯与18g的六氟磷酸锂混合以制备基础电解液，电解液添加2.0g由式(1-1)表示的第一添加剂和1.5g由TMSB表示的第二添加剂搅拌均匀后，添加到电池内制备CR2016纽扣电池。
实施例5
采用与实施例1相同的方法制备纽扣电池，不同之处在于：将20g的碳酸亚乙酯、62g的碳酸二甲酯与18g的六氟磷酸锂混合以制备基础电解液，电解液添加3.0g由式(1-1)表示的第一添加剂和3.0g由TMSB表示的第二添加剂搅拌均匀后，添加到电池内制备CR2016纽扣电池。
实施例6
采用与实施例1相同的方法制备纽扣电池，不同之处在于：将20g的碳酸亚乙酯、62g的碳酸二甲酯与18g的六氟磷酸锂混合以制备基础电解液，电解液添加1.0g由式(1-2)表示的第一添加剂和1.0g由TMSP表示的第二添加剂搅拌均匀后，添加到电池内制备CR2016纽扣电池。
Figure PCTCN2022123523-appb-000017
式(1-2)(1,2-二(3-三氟甲基苯基)-3,3,4,4,5,5-六氟-环戊烯-1)
Figure PCTCN2022123523-appb-000018
TMSP(磷酸三(三甲基硅基)酯)
实施例7
采用与实施例1相同的方法制备纽扣电池，不同之处在于：将20g的碳酸亚乙酯、62g的碳酸二甲酯与18g的六氟磷酸锂混合以制备基础电解液，电解液添加2.0g由式(1-2)表示的第一添加剂和1.5g由TMSP表示的第二添加剂搅拌均匀后，添加到电池内制备CR2016纽扣电池。
实施例8
采用与实施例1相同的方法制备纽扣电池，不同之处在于：将20g的碳酸亚乙酯、62g的碳酸二甲酯与18g的六氟磷酸锂混合以制备基础电解液，电解液添加3.0g由式(1-2)表示的第一添加剂和3.0g由TMSP表示的第二添加剂搅拌均匀后，添加到电池内制备CR2016纽扣电池。
实施例9
采用与实施例1相同的方法制备纽扣电池，不同之处在于：将20g的碳酸亚乙酯、62g的碳酸二甲酯与18g的六氟磷酸锂混合以制备基础电解液，电解液添加1.0g由式(1-1)表示的第一添加剂和1.0g由TMSP表示的第二添加剂搅拌均匀后，添加到电池内制备CR2016纽扣电池。
实施例10
采用与实施例1相同的方法制备纽扣电池，不同之处在于：将20g的碳酸亚乙酯、62g的碳酸二甲酯与18g的六氟磷酸锂混合以制备基础电解液，电解液添加1.0g由式(1-2)表示的第一添加剂和1.0g由TMSB表示的第二添加剂搅拌均匀后，添加到电池内制备CR2016纽扣电池。
比较例1
采用与实施例1相同的方法制备纽扣电池，不同之处在于：将20g的碳酸亚乙酯、62g的碳酸二甲酯与18g的六氟磷酸锂混合以制备基础电解液，添加到电池内制备CR2016纽扣电池。
比较例2
采用与实施例1相同的方法制备纽扣电池，不同之处在于：将20g的碳酸亚乙酯、62g的碳酸二甲酯与18g的六氟磷酸锂混合以制备基础电解液，电解液添加2.0g由式(1-1)表示的第一添加剂搅拌均匀后，添加到电池内制备CR2016纽扣电池。
比较例3
采用与实施例1相同的方法制备纽扣电池，不同之处在于：将20g的碳酸亚乙酯、62g的碳酸二甲酯与18g的六氟磷酸锂混合以制备基础电解液，电解液添加2.0g由TMSB表示的第二添加剂搅拌均匀后，添加到电池内制备CR2016纽扣电池。
比较例4
采用与实施例1相同的方法制备纽扣电池，不同之处在于：将20g的碳酸亚乙酯、62g的碳酸二甲酯与18g的六氟磷酸锂混合以制备基础电解液，电解液添加2.0g由式(1-2)表示的第一添加剂搅拌均匀后，添加到电池内制备CR2016纽扣电池。
电池性能的测试
在室温下，在2.75V至4.3V之间的电压下对实施例1-10和比较例1-4中的镍钴酸锂纽扣电池进行充放电测试和阻抗测试。将上述实施例及比较例中的电池首先在室温下进行0.1C的循环测试1次，然后在60℃的条件下进行1C的充电和1C放电的循环测试100次，从而确定电池的循环保持率，最后在60℃的条件下进行1C的充电测试1次，确定电池的阻抗值。实验结果在下表1、图1和图2中示出。
表1电池性能测试结果
Figure PCTCN2022123523-appb-000019
在表1中，“第一添加剂添加量”和“第二添加剂添加量”均为基于基础电解液的总重量的重量百分比。
从以上的测试结果可以看出，本发明的上述实施例实现了如下技术效果：
通过实施例2与比较例2的结果比较可以看出，与仅添加第一添加剂的比较例2相比，在电解液添加剂包括第一添加剂和第二添加剂的组合的实施例2中的电池具有更高的循环保持率和更低的循环后阻抗。通过实施例2与比较例3的结果比较可以看出，与仅添加第二添加剂的比较例3相比，在电解液添加剂包括第一添加剂和第二添加剂的组合的实施例2中的电池具有显著更高的循环保持率和稍高的循环后阻抗。通过实施例2与比较例1的结果比较可以看出，与没有添加任何电解液添加剂的比较例1相比，在电解液添加剂包括第一添加剂和第二添加剂的组合的实施例2中的电池具有更高的循环保持率和更低的循环后阻抗。
通过实施例6与比较例4的结果比较可以看出，与仅添加第一添加剂的比较例4相比，在电解液添加剂包括第一添加剂和第二添加剂的组合的实施例6中的电池具有更高的循环保持率和更低的循环后阻抗。通过实施例6与比较例1的结果比较可以看出，与没有添加任何电解液添加剂的比较例1相比，在电解液添加剂包括第一添加剂和第二添加剂的组合的实施例6中的电池具有更高的循环保持率和稍高的循环后阻抗。
通过比较例1与比较例2的结果比较可以看出，通过添加第一添加剂可以改善电池的循环保持率，但是循环后阻抗较大。通过比较例1与比较例3的结果比较可以看出，通过添加第二添加剂可以降低电池的循环后阻抗，但是循环保持率显著降低。由此可见，通过单独添加第一添加剂可以改善电池的循环保持率，但是循环后阻抗较大；通过单独添加第二添加剂可以降低电池的循环后阻抗，但是循环保持率显著降低。
通过实施例1-10与比较例1的结果比较可以看出，与没有添加任何电解液添加剂的比较例1相比，其中电解液添加剂包括第一添加剂和第二添加剂的组合的实施例1-10能够保证在循环后阻抗降低或者没有大幅升高的情况下，使得电池具有更高的循环保持率。尤其是，通过实施例2-4和实施例10与比较例1的结果比较可以看出，与没有添加任何电解液添加剂的比较例1相比，在电解液添加剂包括第一添加剂和第二添加剂的组合的实施例2-4和实施例10中的电池具有更高的循环保持率和更低的循环后阻抗。由此可见，与比较例1相比，其中电解液添加剂包括第一添加剂和第二添加剂的组合的实施例2-4和实施例10具有更好的效果，对循环保持率和循环后阻抗都实现了优化。
通过实施例2-4和实施例9与比较例2的结果比较可以看出，与仅添加第一添加剂的比较例2相比，在电解液添加剂包括第一添加剂和第二添加剂的组合的实施例2-4和实施例9中的电池具有更高的循环保持率和更低的循环后阻抗。由此可见，与比较例2相比，其中电解液添加剂包括第一添加剂和第二添加剂的组合的实施例2-4和实施例9不仅降低了循环后阻抗，而且还实现了循环保持率的进一步提升。
通过实施例1-5与比较例3的结果比较可以看出，与仅添加第二添加剂的比较例3相比，在电解液添加剂包括第一添加剂和第二添加剂的组合的实施例1-5中的电池在维持较低的循环后阻抗的情况下大幅提高了循环保持率。
通过实施例6、实施例7和实施例10与比较例4的结果比较可以看出，与仅添加第一添加剂的比较例4相比，其中电解液添加剂包括第一添加剂和第二添加剂的组合的实施例6、实施例7和实施例10不仅降低了循环后阻抗，而且还实现了循环保持率的进一步提升。
通过实施例2-3和实施例9与比较例2的结果比较以及通过实施例6和实施例10与比较例4的结果比较可以看出，在添加剂的总量相同的情况下，与单独使用第一添加剂的情况相比，通过将第一添加剂和第二添加剂组合使用，可以改善电池的循环保持率并且可以降低电池的循环后阻抗。
由此可见，与不添加任何电解液添加剂的情况以及单独添加第一添加剂或第二添加剂的情况相比，本发明利用第一添加剂和第二添加剂的组合可以产生协同作用，从而在电池的循环保持率和循环后阻抗之间获得较好的平衡。
由上述电池性能测试结果可以看出：本发明通过两种添加剂的组合，在电池的循环保持率和循环后阻抗方面均表现出优异的效果，因此，通过本发明的电解液添加剂有效降低了锂离子二次电池的内阻并且提高了锂离子二次电池的循环性能。

Claims (10)

  1. 一种电解液添加剂，其特征在于，所述电解液添加剂包括第一添加剂和第二添加剂，所述第一添加剂具有由以下式(1)所示的结构：
    Figure PCTCN2022123523-appb-100001
    其中，R 1和R 2各自独立地选自氟，C 1至C 3烷氧基，或者可选被氟、C 1至C 3烷基或C 1至C 3全氟烷基取代的苯基，
    所述第二添加剂选自以下物质中的任一种：
    Figure PCTCN2022123523-appb-100002
    或者
    Figure PCTCN2022123523-appb-100003
  2. 根据权利要求1所述的电解液添加剂，其特征在于，R 1和R 2各自独立地选自被C 1至C 3全氟烷基取代的苯基。
  3. 根据权利要求2所述的电解液添加剂，其特征在于，R 1和R 2各自独立地选自被三氟甲基取代的苯基。
  4. 根据权利要求1至3中任一项所述的电解液添加剂，其特征在于，所述第二添加剂为
    Figure PCTCN2022123523-appb-100004
  5. 根据权利要求1所述的电解液添加剂，其特征在于，所述第一添加剂选自以下物质中的任一种：
    Figure PCTCN2022123523-appb-100005
    Figure PCTCN2022123523-appb-100006
    或者
    Figure PCTCN2022123523-appb-100007
  6. 根据权利要求1至3中任一项所述的电解液添加剂，其特征在于，所述第一添加剂与所述第二添加剂的重量比在1:3至4:3的范围内。
  7. 一种电解液，包含有机溶剂、锂盐以及权利要求1至6中任一项所述的电解液添加剂。
  8. 根据权利要求7所述的电解液，其特征在于，基于100重量份的所述有机溶剂与所述锂盐，所述第一添加剂的量在0.1重量份至3.0重量份的范围内，优选地所述第一添加剂的量在0.1重量份至2.0重量份的范围内。
  9. 根据权利要求7所述的电解液，其特征在于，基于100重量份的所述有机溶剂与所述锂盐，所述第二添加剂的量在0.1重量份至3.0重量份的范围内，优选地所述第二添加剂的量在0.1重量份至2.0重量份的范围内。
  10. 一种锂离子二次电池，其特征在于，包括：
    正极，
    负极，
    隔膜，以及
    权利要求7至9中任一项所述的电解液。
PCT/CN2022/123523 2021-12-14 2022-09-30 电解液添加剂、电解液以及包含其的锂离子二次电池 WO2023109259A1 (zh)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202111525506.0A CN116264322A (zh) 2021-12-14 2021-12-14 电解液添加剂、电解液以及包含其的锂离子二次电池
CN202111525506.0 2021-12-14

Publications (1)

Publication Number Publication Date
WO2023109259A1 true WO2023109259A1 (zh) 2023-06-22

Family

ID=86721969

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2022/123523 WO2023109259A1 (zh) 2021-12-14 2022-09-30 电解液添加剂、电解液以及包含其的锂离子二次电池

Country Status (2)

Country Link
CN (1) CN116264322A (zh)
WO (1) WO2023109259A1 (zh)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116885278A (zh) * 2023-07-26 2023-10-13 华南师范大学 电解液及钠离子电池

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015149234A (ja) * 2014-02-07 2015-08-20 三井化学株式会社 電池用非水電解液、及びリチウム二次電池
CN105375066A (zh) * 2015-12-16 2016-03-02 东莞市杉杉电池材料有限公司 一种适用于硅碳负极锂离子电池电解液及硅碳负极锂离子电池
CN107275676A (zh) * 2017-08-04 2017-10-20 广州天赐高新材料股份有限公司 一种用于硅基锂二次电池的电解液和硅基锂二次电池
CN108470938A (zh) * 2017-02-23 2018-08-31 宁德时代新能源科技股份有限公司 锂离子电池及其电解液
CN110945705A (zh) * 2017-07-27 2020-03-31 株式会社村田制作所 二次电池用电解液、二次电池、电池包、电动车辆、电力储存系统、电动工具及电子设备

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015149234A (ja) * 2014-02-07 2015-08-20 三井化学株式会社 電池用非水電解液、及びリチウム二次電池
CN105375066A (zh) * 2015-12-16 2016-03-02 东莞市杉杉电池材料有限公司 一种适用于硅碳负极锂离子电池电解液及硅碳负极锂离子电池
CN108470938A (zh) * 2017-02-23 2018-08-31 宁德时代新能源科技股份有限公司 锂离子电池及其电解液
CN110945705A (zh) * 2017-07-27 2020-03-31 株式会社村田制作所 二次电池用电解液、二次电池、电池包、电动车辆、电力储存系统、电动工具及电子设备
CN107275676A (zh) * 2017-08-04 2017-10-20 广州天赐高新材料股份有限公司 一种用于硅基锂二次电池的电解液和硅基锂二次电池

Also Published As

Publication number Publication date
CN116264322A (zh) 2023-06-16

Similar Documents

Publication Publication Date Title
JP4837614B2 (ja) リチウム二次電池
KR101201804B1 (ko) 리튬 이차 전지용 음극, 이의 제조 방법 및 이를 포함하는 리튬 이차 전지
US10044072B2 (en) Lithium secondary battery pack, as well as electronic device, charging system, and charging method using said pack
KR102460957B1 (ko) 리튬 이차 전지용 전해액 및 이를 포함하는 리튬 이차 전지
KR20180041602A (ko) 리튬 이차전지용 전해액 및 이를 포함하는 리튬 이차전지
KR100984134B1 (ko) 리튬 이차 전지용 전해액 및 이를 포함하는 리튬 이차 전지
WO2023109259A1 (zh) 电解液添加剂、电解液以及包含其的锂离子二次电池
KR20200126781A (ko) 리튬 이차 전지용 비수 전해질 및 이를 포함하는 리튬 이차 전지
CN117136444A (zh) 锂二次电池
CN110797573B (zh) 锂二次电池
EP4131550A1 (en) Electrolyte additive for secondary battery, non-aqueous electrolyte comprising same for lithium secondary battery, and lithium secondary battery
KR102426254B1 (ko) 리튬 이차전지용 전해질 첨가제를 포함하는 리튬 이차전지
CN114616709A (zh) 二次电池用电解液添加剂、锂二次电池用非水电解液及包含其的锂二次电池
WO2023051012A1 (zh) 电解液添加剂、电解液以及包含其的锂离子二次电池
JP7408226B2 (ja) リチウム二次電池用非水電解液及びこれを含むリチウム二次電池
KR102619182B1 (ko) 리튬 이차전지용 비수전해액 및 이를 포함하는 리튬 이차전지
JP7118479B2 (ja) リチウム二次電池用電解質及びこれを含むリチウム二次電池
US20220021031A1 (en) Electrolyte additive, electrolyte, lithium ion secondary battery containing the same and use thereof
CN116936925A (zh) 制备锂离子二次电池的方法及由其制备的锂离子二次电池
WO2023005940A1 (zh) 用于锂离子电池电解液的添加剂、包含其的电解液及锂离子二次电池
CN116802875A (zh) 锂二次电池
US20230109679A1 (en) Additive for electrolyte, electrolyte, and electrochemical device
CN118020189A (zh) 锂二次电池用非水电解液及包含其的锂二次电池
WO2022203047A1 (ja) 非水系電解液及びそれを用いた非水系電解液電池
CN115775919A (zh) 锂二次电池

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: 22906011

Country of ref document: EP

Kind code of ref document: A1