WO2024096043A1 - リチウムイオン二次電池用電解液及びリチウムイオン二次電池 - Google Patents

リチウムイオン二次電池用電解液及びリチウムイオン二次電池 Download PDF

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WO2024096043A1
WO2024096043A1 PCT/JP2023/039392 JP2023039392W WO2024096043A1 WO 2024096043 A1 WO2024096043 A1 WO 2024096043A1 JP 2023039392 W JP2023039392 W JP 2023039392W WO 2024096043 A1 WO2024096043 A1 WO 2024096043A1
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ion secondary
lithium ion
electrolyte
secondary batteries
aqueous solvent
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French (fr)
Japanese (ja)
Inventor
凌平 小川
仁志 福満
瞳 藤々木
遼 松村
浩司 安部
ヤンコ マリノフ トドロフ
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Kyocera Corp
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Kyocera Corp
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Priority to CN202380075029.3A priority Critical patent/CN120113081A/zh
Priority to JP2024554547A priority patent/JPWO2024096043A1/ja
Priority to EP23885797.3A priority patent/EP4614649A1/en
Publication of WO2024096043A1 publication Critical patent/WO2024096043A1/ja
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M10/0568—Liquid materials characterised by the solutes
    • 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
    • H01M10/0569—Liquid materials characterised by the solvents
    • 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
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0034—Fluorinated solvents
    • 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
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0037—Mixture of solvents
    • 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

  • This disclosure relates to an electrolyte for lithium ion secondary batteries that has excellent battery characteristics such as the cycle life of the battery, and a lithium ion secondary battery that includes the electrolyte.
  • LIBs lithium-ion secondary batteries
  • Patent Document 1 proposes a lithium ion secondary battery that exhibits excellent cycle characteristics by using a nonaqueous electrolyte solution containing a formic acid ester instead of a nonaqueous electrolyte solution in which electrolytes LiPF6 or LiBF4 are dissolved in a nonaqueous solvent (e.g., EC, PC, MEC, etc.).
  • a nonaqueous solvent e.g., EC, PC, MEC, etc.
  • the formate esters described in Patent Document 1 are compounds having a hydrocarbon group, such as octyl formate, allyl formate, and 2-propynyl formate, and cyanomethyl formate having a -C ⁇ N group is not disclosed anywhere.
  • the electrolyte for lithium ion secondary batteries is an electrolyte for lithium ion secondary batteries in which an electrolyte salt is dissolved in a non-aqueous solvent, and contains cyanomethyl formate and vinylene carbonate.
  • the lithium ion secondary battery according to one embodiment of the present disclosure is a lithium ion secondary battery including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution in which an electrolyte salt is dissolved in a non-aqueous solvent, and contains cyanomethyl formate and vinylene carbonate as the lithium ion secondary battery electrolyte solution in which an electrolyte salt is dissolved in a non-aqueous solvent.
  • FIG. 1 is a cross-sectional view showing the structure of a lithium-ion secondary battery.
  • the present disclosure solves the above-mentioned problems and provides a lithium-ion secondary battery with excellent cycle characteristics, which are important for secondary batteries for in-vehicle use such as electric vehicles, residential storage batteries, or large-scale power storage systems. It also provides an electrolyte that can be used to make such lithium-ion secondary batteries.
  • the electrolyte for lithium ion secondary batteries is a non-aqueous electrolyte in which an electrolyte salt is dissolved in a non-aqueous solvent.
  • the electrolyte for lithium ion secondary batteries of the present disclosure contains cyanomethyl formate and vinylene carbonate (VC).
  • the electrolyte salt is not particularly limited, but examples thereof include electrolyte salts such as LiN(SO 2 F) 2 (hereinafter also referred to as LiFSI) having a SO 2 group, LiOSO 2 F having a SO 3 group, LiOSO 3 CH 3 , LiOSO 3 C 2 H 5 having a SO 4 group, LiPF 6 , LiPO 2 F 2 having phosphorus (P), lithium difluorobis(oxalato)phosphate (LiDFOP), LiBF 4 having boron (B), lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB), and lithium salts such as LiAsF 6 having arsenic (As).
  • one type of electrolyte salt may be used, or two or more types may be mixed and used.
  • the lithium salt may be used alone or in combination of two or more kinds.
  • the lithium salt include LiFSI, LiPF 6 , LiN(SO 2 F) 2 , LiPO 2 F 2 , and LiOSO 3 CH 3. If the concentration of the electrolyte salt is too low, the battery performance is reduced because there are few lithium ions moving through the electrolyte. If the concentration of the electrolyte salt is too high, the viscosity of the electrolyte increases, making it difficult for the lithium ions to move, and therefore the battery performance is reduced.
  • the electrolyte salt may be at least one of LiPF 6 and LiN(SO 2 F) 2.
  • the total concentration of the electrolyte salt may be in the range of 0.5 to 3 mol per 1 L of the volume of the non-aqueous solvent, or may be in the range of 0.8 to 2 mol.
  • LiFSI can be used in large quantities because it has high chemical thermal stability and can improve battery performance at high temperatures, as it has improved corrosion resistance against metals such as aluminum. It is preferable to add a certain amount of Li salts other than LiFSI because they have the effect of auxiliary improvement of battery performance at low temperatures.
  • a suitable combination of these lithium salts a combination of two types of lithium salts, a lithium salt having SO 2 groups and a lithium salt having phosphorus (P), or a combination of three types of lithium salts, a lithium salt having SO 2 groups, a lithium salt having SO 4 groups, and a lithium salt having phosphorus (P), is preferable.
  • the mass ratio of LiFSI to other Li salts is preferably 100:0 to 1:99, more preferably 100:0 to 50:50, and most preferably 100:0 to 70:30.
  • the non-aqueous solvent in the present disclosure is not particularly limited as long as it is generally used as a non-aqueous solvent for electrolytes for lithium ion batteries, but examples thereof include cyclic carbonates, chain carbonates, and the like.
  • Suitable examples of cyclic carbonates include ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), and the like.
  • Suitable examples of chain carbonates include dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and the like.
  • the non-aqueous solvent may also include the cyclic compound gamma-butyrolactone (GBL).
  • the non-aqueous solvent may also include at least two selected from ethylene carbonate (EC), propylene carbonate (PC), and gamma-butyrolactone (GBL).
  • EC ethylene carbonate
  • PC propylene carbonate
  • GBL gamma-butyrolactone
  • the flash point of EC is 143°C
  • PC propylene carbonate
  • GBL has a flash point of 100°C
  • the non-aqueous solvent contains at least two types selected from EC, PC, and GBL in a total amount of 80 to 100% by volume.
  • the above volume percentage is a ratio to the total volume of the non-aqueous solvent.
  • the non-aqueous solvent contains at least two types selected from EC, PC, and GBL in a total amount of 90 to 100% by volume.
  • the nonaqueous electrolyte solution of the present disclosure may be used by mixing additives in addition to the nonaqueous solvent.
  • additives to be mixed with the main solvent include at least one selected from fluoroethylene carbonate, succinic anhydride, maleic anhydride, biphenyl, LiBF 2 (C 2 O 4 ), LiB(C 2 O 4 ) 2 (LiBOB), 1,3-propane sultone, and ethylene sulfate.
  • the nonaqueous solvent may contain 10% by weight or less of additives, 5% by weight or less, or 3% by weight or less, based on 100% by weight of the entire nonaqueous solvent.
  • cyanomethyl formate used in this disclosure.
  • the first is that its molecular weight is smaller than that of DMC, which is used as one of the main solvents, which is 90. Also, its molecular weight is 85, which is smaller than that of VC, which is an additive currently used worldwide, which is 86. Since additives act electrochemically in molar amounts, it is important from the performance and cost perspectives that a small amount of additive can provide a high additive effect.
  • cyanomethyl formate has an oxidative decomposition potential of 5.4 V for cyanomethyl formate, while VC has an oxidative decomposition potential of 4.85 V, and a reductive decomposition potential of 1.1 V for cyanomethyl formate, while VC has an oxidative decomposition potential of 0.8 V for cyanomethyl formate. Therefore, cyanomethyl formate is a compound that is more difficult to oxidize and more easily reduce than VC.
  • cyanomethyl formate is less susceptible to oxidative decomposition on a Ni positive electrode, and it is advantageous from the performance perspective to quickly reductively decompose on a highly active graphite negative electrode and form a protective coating.
  • the amount of cyanomethyl formate contained in the electrolyte for lithium ion secondary batteries of the present disclosure is not particularly limited, but if it is too small, the formation of a protective film on the negative electrode will be insufficient, resulting in reduced cycle characteristics. If the amount of cyanomethyl formate contained is too large, the protective film on the negative electrode will become thicker, increasing the resistance of the negative electrode and resulting in reduced cycle characteristics.
  • the amount of cyanomethyl formate contained in the total weight of the non-aqueous solvent is not particularly limited, but may be 0.01 to 10% by weight, 0.01 to 7% by weight, or 0.1 to 5% by weight.
  • the electrolyte for lithium ion secondary batteries disclosed herein may contain, in addition to cyanomethyl formate, at least one compound selected from the group consisting of a phosphonate ester compound represented by the following formula (I), a carbonate ester compound represented by the following formula (II), an oxalate ester compound represented by the following formula (III), and a methanesulfonate ester compound represented by the following formula (IV), in order to further improve the corrosion resistance in lithium ion secondary batteries.
  • a phosphonate ester compound represented by the following formula (I) a carbonate ester compound represented by the following formula (II)
  • an oxalate ester compound represented by the following formula (III) an oxalate ester compound represented by the following formula (III)
  • a methanesulfonate ester compound represented by the following formula (IV) in order to further improve the corrosion resistance in lithium ion secondary batteries.
  • a and B each independently represent a methyl group, an ethyl group, a 2-cyanoethyl group (propionitrile group), a 1-cyanoethyl group, a 2-cyano-2-propyl group, or a 2-propynyl group (propargyl group), and B represents a methyl group, an ethyl group, a vinyl group, or a cyanomethyl group.
  • the 24 types of phosphonate compounds represented by formula (I) are shown in Table 1.
  • C and D each independently represent a methyl group or an ethyl group, and D represents a 2-cyanoethyl group (propionitrile group), a 1-cyanoethyl group, a 2-cyano-2-propyl group, or a 2-propynyl group (propargyl group).
  • the carbonate ester compounds represented by formula (II) are eight types shown in Table 2.
  • E represents a 2-cyanoethyl group (propionitrile group), a 1-cyanoethyl group, a 2-cyano-2-propyl group, or a 2-propynyl group (propargyl group).
  • the oxalic acid ester compounds represented by formula (III) are four types shown in Table 3.
  • F represents a 2-cyanoethyl group (propionitrile group), a 1-cyanoethyl group, a 2-cyano-2-propyl group, or a 2-propynyl group (propargyl group).
  • the methanesulfonate compounds represented by formula (IV) are four types shown in Table 4.
  • the reason why the above phosphonate ester compound (I), carbonate ester compound (II), oxalate ester compound (III), and methanesulfonate ester compound (IV) are preferably used in combination is only speculation, but it is believed that they form a strong adsorption layer on the metal surface such as aluminum, preventing contact with corrosive compounds.
  • the total content of at least one type selected from these 40 types, that is, a combination of one or more types, is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, and most preferably 0.5% by weight or more, based on the total mass of the electrolyte for lithium ion secondary batteries of the present disclosure.
  • the upper limit is preferably 10% by weight or less, more preferably 7% by weight or less, and most preferably 5% by weight or less, based on the non-aqueous solvent.
  • the preferred range of the total content of these compounds can be 0.01 to 10% by weight, 0.01 to 7% by weight, 0.1 to 5% by weight, etc., based on the total mass of the electrolyte for lithium ion secondary batteries of the present disclosure.
  • the electrolyte for lithium ion secondary batteries of the present disclosure contains at least one compound selected from the phosphonate ester compounds, carbonate ester compounds, oxalate ester compounds, and methanesulfonate ester compounds of the present disclosure, and when used in a lithium ion secondary battery, the electrolyte for lithium ion secondary batteries can further improve the corrosion resistance of the lithium ion secondary batteries, particularly the corrosion resistance in use at high voltages exceeding 4.2 V and the corrosion resistance in use at room temperature or higher.
  • the electrolyte for lithium ion secondary batteries of the present disclosure may contain other components in addition to the electrolyte, nonaqueous solvent, cyanomethyl formate, and compounds represented by formulas (I), (II), (III), and (IV) within the scope of their usability as electrolytes.
  • This disclosure makes it possible to use non-aqueous electrolytes containing 1,3-propane sultone, which is usually highly corrosive and has been avoided for use, without impairing the corrosion resistance of LIB.
  • 1,3-propane sultone has the effect of suppressing the reductive decomposition of EC and PC on the graphite negative electrode, so it is preferable to add it in the range of 0.1 to 5 wt % of the total non-aqueous electrolyte.
  • this disclosure makes it possible to use non-aqueous electrolytes containing dinitriles with a carbon chain length of 2 to 5, such as succinonitrile, glutaronitrile, adiponitrile, and pimelonitrile, isocyanates such as hexamethylene diisocyanate (HMDI) and 1,3-bis(isocyanatomethyl)cyclohexane (a mixture of cis- and trans-), and carbodiimides such as N,N'-diisopropylcarbodiimide (DIC) and N,N'-dicyclohexylcarbodiimide (DCC), without impairing the cycle characteristics of the LIB. It is preferable to add these compounds in the range of 0.1 to 5% by weight relative to the total amount of the non-aqueous electrolyte.
  • HMDI hexamethylene diisocyanate
  • DIC N,N'-diisopropylcarbodiimide
  • DCC N,N'-
  • the content of vinylene carbonate relative to the weight of the entire non-aqueous solvent may be 0.01 to 10% by weight, 0.01 to 7% by weight, or 0.1 to 5% by weight. If the content of vinylene carbonate is too low, the formation of a protective film on the negative electrode becomes insufficient, resulting in reduced cycle characteristics. If the content of vinylene carbonate is too high, the protective film on the negative electrode becomes thick, increasing the resistance of the negative electrode and resulting in reduced cycle characteristics.
  • the electrolyte for lithium ion secondary batteries of the present disclosure can improve the cycle characteristics of the lithium ion secondary battery when used in the battery.
  • the electrolyte for lithium ion secondary batteries disclosed herein may further contain at least one of trioctyl phosphate, trifluoroacetate, and pivalate ester having an alcohol group with a carbon chain length of 6 to 8.
  • Trioctyl phosphate, trifluoroacetate, and pivalate ester having an alcohol group with a carbon chain length of 6 to 8 are preferably added in a certain amount because they have the effect of increasing the permeability of the electrolyte into the separator and reducing the interfacial resistance between the separator and the electrode.
  • the content of each of trioctyl phosphate, trifluoroacetate, and pivalate ester having an alcohol group with a carbon chain length of 6 to 8 may be 0.1 to 3 wt%, 0.5 to 2 wt%, or 1 to 1.5 wt%, based on 100 wt% of the non-aqueous solvent.
  • the trifluoroacetic acid ester is not particularly limited, but may be at least one selected from n-hexyl trifluoroacetate, 2-ethylhexyl trifluoroacetate, n-heptyl trifluoroacetate, n-octyl trifluoroacetate, 2-octyl trifluoroacetate, 3-octyl trifluoroacetate, and 4-octyl trifluoroacetate.
  • the pivalic acid ester is not particularly limited, but may be at least one selected from n-hexyl pivalate, 2-ethylhexyl pivalate, n-heptyl pivalate, n-octyl pivalate, 2-octyl pivalate, 3-octyl pivalate, and 4-octyl pivalate.
  • the lithium ion secondary battery of the present disclosure comprises a positive electrode, a negative electrode, a separator, and the electrolyte for the lithium ion secondary battery of the present disclosure.
  • the positive electrode, the negative electrode, and the separator in the present disclosure are not particularly limited as long as they can be used in a lithium ion secondary battery.
  • As the separator in the present disclosure it is most preferable to use a separator made of a microporous film formed from a polyolefin material such as polypropylene or polyethylene, but a nonwoven fabric separator can also be used.
  • the porous sheet or nonwoven fabric may be of a single layer or multilayer structure, and the separator surface may be coated with an oxide such as alumina.
  • the thickness of the separator needs to be as thin as possible to increase the volumetric energy density of the battery. Therefore, it is preferably 20 ⁇ m or less, and particularly preferably 10 ⁇ m or less.
  • the negative electrode active material used in the negative electrode of the present disclosure may include at least one selected from graphite, non-graphitizable carbon, silicon, silicon oxide, lithium titanate, and tin.
  • the negative electrode active material may be a graphite material such as natural graphite or artificial graphite, or a carbon material such as hard carbon or soft carbon.
  • titanium oxides having a spinel structure such as Li 4 Ti 5 O 12 (LTO) that do not expand or contract during charging and discharging, or titanium oxides such as TiNb 2 O 7 and Ti 2 Nb 10 O 29 may be used.
  • Binders used in the negative electrode composite include, for example, ethylene propylene diene terpolymer (EPDM), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene-butadiene copolymer (SBR), acrylonitrile-butadiene copolymer (NBR), and carboxymethyl cellulose (CMC).
  • EPDM ethylene propylene diene terpolymer
  • PTFE polytetrafluoroethylene
  • PVDF polyvinylidene fluoride
  • SBR styrene-butadiene copolymer
  • NBR acrylonitrile-butadiene copolymer
  • CMC carboxymethyl cellulose
  • the positive electrode active material used in the positive electrode of the present disclosure may include a lithium metal compound containing at least one metal element selected from the group consisting of cobalt, nickel, manganese, and iron.
  • the positive electrode active material is, for example, LiCoO2 (LCO), LiCo1 / 3Ni1 / 3Mn1/ 3O2 in which part of the Co is replaced with Ni , LiNi0.5Co0.2Mn0.3O2 ( NCM523 ) , LiNi0.6Co0.2Mn0.2O2 ( NCM622 ) , LiNi0.8Co0.1Mn0.1O2 ( NCM811 ) , LiNi0.8Co0.15Al0.05O2 ( NCA ) , LiNi0.5Mn1.5O4 without Co , LiNi0.8Mn0.13Ti0.02Mg 0.02Nb0.01Mo0.02O2 (HE-LNMO) , etc.
  • LCO LiCoO2
  • NCM523, NCM622, NCM811, NCA, HE-LNMO , etc. may be used as a positive electrode active material containing a lithium composite oxide with an atomic ratio of Ni of 50% or more.
  • LiMn2O4 (LMO) having a spinel structure and LiFePO4 (LFP) having an olivine structure may be used.
  • Conductive assistants used in the positive electrode composite include, for example, known or commercially available conductive assistants such as carbon blacks such as acetylene black and ketjen black, carbon nanotubes, carbon fibers, activated carbon, and graphite. Binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVFF), styrene-butadiene copolymers (SBR), acrylonitrile-butadiene copolymers (NBR), and carboxymethyl cellulose (CMC).
  • PTFE polytetrafluoroethylene
  • PVFF polyvinylidene fluoride
  • SBR styrene-butadiene copolymers
  • NBR acrylonitrile-butadiene copolymers
  • CMC carboxymethyl cellulose
  • the positive electrode is produced, for example, by kneading the conductive assistant and binder with the positive electrode active material to produce a slurry-like positive electrode composite, applying the positive electrode composite to an aluminum foil current collector, drying, pressurizing, and then heating at, for example, 80°C under vacuum. If the battery can be assembled without using a binder, the binder need not be used.
  • the combination of positive and negative electrode active materials may be, in order to increase the volumetric energy density, combinations of LCO and graphite, NCM523 and graphite, NCM622 and graphite, NCM811 and graphite, NCA and graphite, HE-LNMO and graphite, etc. Furthermore, in order to improve rapid charging and discharging, combinations of NCM811 and LTO, HE-LNMO and LTO, LFP and LTO, etc. may be used.
  • the current collector used in the present disclosure is not particularly limited, but aluminum foil or copper foil is preferable, and a porous current collector may be used to further improve the permeability of the electrolyte.
  • the solvent used for the binder there are no particular limitations on the solvent used for the binder, and various solvents can be selected depending on the active material or binder used. Specifically, when PVDF is used as the binder, it is preferable to use N-methyl-2-pyrrolidone as the solvent, while when a rubber-based binder such as styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinyl alcohol, or carboxymethyl cellulose (CMC) is used, water is a suitable solvent.
  • SBR styrene butadiene rubber
  • CMC carboxymethyl cellulose
  • the structure of the lithium ion secondary battery disclosed herein is not particularly limited, but examples of the shape of the secondary battery having a positive electrode, a negative electrode, and a separator include a coin-type battery, a cylindrical battery, a square battery, a pouch-type battery, etc.
  • FIG. 1 is a cross-sectional view showing the structure of a lithium-ion secondary battery 14.
  • the negative electrode active material layer 11b may be a layer of a negative electrode material that is a mixture of a negative electrode active material 11c, a conductive assistant 11d, and an electrolyte 11f.
  • the positive electrode active material layer 12b may be a layer of a positive electrode material that is a mixture of a positive electrode active material 12c, a conductive assistant 12d, and an electrolyte 12f.
  • the negative electrode material may be composed of a negative electrode active material 11c, a conductive assistant 11d, and an electrolyte 11f.
  • the negative electrode 11 may be an electrode in which the negative electrode material is applied to a current collector 11a.
  • the positive electrode material may be composed of a positive electrode active material 12c, a conductive assistant 12d, and an electrolyte 12f.
  • the positive electrode 12 may be an electrode in which the positive electrode material is applied to a current collector 12a.
  • the lithium ion secondary battery 14 may further include a separator 13.
  • the negative electrode 11, the positive electrode 12, and the separator 13 may be positioned such that the negative electrode active material layer 11b and the positive electrode active material layer 12b are in contact with the separator 13. That is, the lithium ion secondary battery 14 may have a structure in which the negative electrode 11 and the positive electrode 12 are stacked with the separator 13 interposed therebetween.
  • the separator 13 may function as an insulating member that insulates the negative electrode 11 and the positive electrode 12. For example, a sheet-like nonwoven fabric or a porous material may be used for the separator 13. Therefore, the first electrolytic solution and the second electrolytic solution can permeate the separator 13.
  • PC represents propylene carbonate
  • DMC represents dimethyl carbonate
  • EMC represents ethyl methyl carbonate
  • FEC represents fluoroethylene carbonate
  • PS represents 1,3 -propane sultone
  • HMDI represents hexamethylene diisocyanate
  • DCC represents N , N'- dicyclohexylcarbodiimide
  • LiFSI represents LiN ( SO2F ) 2
  • NCM523 represents LiNi0.5Co0.2Mn0.3O2
  • NCM811 represents LiNi0.8Co0.1Mn0.1O2
  • LCO represents LiCoO2 .
  • Examples 1-1 to 1-2 An electrolyte solution was prepared according to the compounds and contents shown in Table 5.
  • Table 5 EC stands for ethylene carbonate
  • PC stands for propylene carbonate
  • GBL stands for ⁇ -butyrolactone.
  • LiPF 6 was dissolved in a non-aqueous solvent in which EC/(PC+GBL) was mixed at a volume ratio of 1:4. Cyanomethyl formate (CMF) (Tokyo Chemical Industry Co., Ltd.) and vinylene carbonate (VC) were added to the solution thus obtained to prepare the electrolyte solutions of Examples 1-1 and 1-2.
  • CMF Cyanomethyl formate
  • VC vinylene carbonate
  • the content of CMF in the electrolyte solution of Example 1-1 was 0.5% by weight
  • the content of VC was 1.5% by weight
  • the content of LiPF 6 was 1 mol/L.
  • the content of CMF in the electrolyte solution of Example 1-2 was 0.25% by weight
  • the content of VC was 0.75% by weight
  • the content of LiPF 6 was 1 mol/L.
  • Comparative Example 1-1 An electrolyte solution of Comparative Example 1-1 was prepared without adding CMF. In Comparative Example 1-1, an electrolyte solution was prepared in the same manner as in Examples 1-1 and 1-2, except that CMF was not added.
  • the positive electrode used NCM523 as an active material, acetylene black as a conductive material, and PVDF as a binder, and the mass ratio of the positive electrode active material, conductive material, and binder was 92:5:3.
  • the positive electrode was coated on aluminum foil, dried, and molded under pressure.
  • the coating weight of the positive electrode was 0.010 g/cm 2.
  • the negative electrode used natural graphite as an active material, SBR and CMC as binders, and the mass ratio of the negative electrode active material and binder was 98:1:1.
  • the negative electrode was coated on copper foil, dried, and molded under pressure.
  • the coating weight of the negative electrode was 0.007 g/cm 2.
  • the positive electrode, the negative electrode, and the separator were used, and the electrolyte solutions of Examples 1-1 to 1-2 and Comparative Example 1-1 were used to prepare coin-type batteries so that the design capacity of the battery was 2 mAh.
  • This coin battery was charged at 25°C with constant current and constant voltage (CC/CV mode) at a rate of 1C up to an upper limit voltage of 4.2V, and the voltage was maintained at 4.2V until the end current was 0.03mA or less. It was then discharged at a rate of 1C down to a lower limit voltage of 3.0V, and the cycle characteristics were measured by repeating the charge and discharge. The results are shown in Table 5. The discharge capacity after 50 charge and discharge cycles is shown as the 50th cycle discharge capacity.
  • EC ethylene carbonate
  • PC propylene carbonate
  • GBL ⁇ -butyrolactone
  • LiFSI stands for LiN(SO 2 F) 2
  • TOP stands for trioctyl phosphate
  • CF-2EH stands for 2-ethylhexyl trifluoroacetate
  • PV-2EH stands for 2-ethylhexyl pivalate
  • MA maleic anhydride
  • BP biphenyl
  • LiBOB stands for LiB(C 2 O 4 ) 2 .
  • LiPF 6 or LiFSI was dissolved in a non-aqueous solvent in which EC/(PC+GBL) was mixed at 1:4 (volume ratio).
  • Cyanomethyl formate (CMF) (Tokyo Chemical Industry Co., Ltd.) and vinylene carbonate (VC) were added to the solution thus obtained to prepare the electrolyte solutions of Examples 2-1 to 2-7.
  • the CMF content in the electrolyte solutions of Examples 2-1 to 2-3 was 0.75% by weight, the VC content was 2.25% by weight, and the LiPF 6 content was 1 mol/L.
  • the CMF content in the electrolyte solutions of Examples 2-4, 2-6, and 2-7 was 1% by weight, the VC content was 1% by weight, and the LiFSI content was 1 mol/L.
  • the CMF content in the electrolyte solution of Example 2-5 was 7% by weight, the VC content was 7% by weight, and the LiFSI content was 1 mol/L.
  • the compounds other than CMF and VC shown in Tables 6 and 7 were added in the amounts shown in the tables to prepare the electrolyte solutions of Examples 2-1 to 2-7.
  • Comparative Examples 2-1 to 2-4 The electrolytic solutions of Comparative Examples 2-1 to 2-3 were prepared without adding CMF.
  • the electrolytic solution of Comparative Example 2-4 was prepared without adding VC.
  • Comparative Examples 2-1, 2-2, and 2-3 the electrolytic solutions were prepared in the same manner as in Examples 2-1, 2-2, and 2-3, respectively, except that CMF was not added.
  • Comparative Example 2-4 the electrolytic solution was prepared in the same manner as in Example 2-4, except that VC was not added.
  • the positive electrode used LiFePO 4 (LFP) as an active material, carbon black as a conductive material, and the above-mentioned electrolyte, and the mass ratio of the positive electrode active material, conductive material, and electrolyte was 72:1:27, and was coated on aluminum foil.
  • the coating weight of the positive electrode was 0.075 g/cm 2.
  • the negative electrode used artificial graphite as an active material, carbon black as a conductive material, and the above-mentioned electrolyte, and the mass ratio of the negative electrode active material, conductive material, and electrolyte was 62:3:35, and was coated on copper foil.
  • the coating weight of the negative electrode was 0.051 g/cm 2.
  • the positive electrode, the negative electrode, and the separator were used, and the electrolytes of Examples 2-1 to 2-7 and Comparative Examples 2-1 to 2-4 were used, respectively, to prepare a pouch-type battery so that the design capacity of the battery was 111 mAh.
  • This pouch-type battery was charged at 45° C. at a constant current and constant voltage (CC/CV mode) at a rate of 0.5 C to an upper limit voltage of 3.6 V, and the voltage was maintained at 3.6 V for 30 minutes. Next, the battery was discharged at a rate of 0.5 C to a lower limit voltage of 2.0 V, and the charge/discharge cycle was repeated to measure the cycle characteristics. The cycle characteristics (%) were quantified by dividing the obtained capacity (mAh/g) by 50th cycle/1st cycle ⁇ 100. The results are shown in Tables 6 and 7.
  • nonaqueous electrolyte of the present disclosure it is possible to improve battery characteristics such as the cycle characteristics of the battery.
  • the contribution of this disclosure to the long-term use of a large number of lithium-ion secondary batteries, such as automotive batteries, is immeasurable.

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WO2026070996A1 (ja) * 2024-09-26 2026-04-02 パナソニックＩｐマネジメント株式会社 二次電池用非水電解質および二次電池
WO2026070997A1 (ja) * 2024-09-26 2026-04-02 パナソニックＩｐマネジメント株式会社 二次電池用非水電解質および二次電池
WO2026070998A1 (ja) * 2024-09-26 2026-04-02 パナソニックＩｐマネジメント株式会社 二次電池用非水電解質および二次電池

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JP2002042865A (ja) * 2000-07-31 2002-02-08 At Battery:Kk 薄型非水系電解液二次電池
JP2002110232A (ja) * 2000-09-29 2002-04-12 Yuasa Corp 非水電解液およびこれを用いたリチウム電池
JP2007534122A (ja) * 2004-04-20 2007-11-22 デグサ ゲーエムベーハー 電解液組成物並びに電気化学的なエネルギー貯蔵系用の電解液材料としてのその使用
WO2010018814A1 (ja) * 2008-08-12 2010-02-18 宇部興産株式会社 非水電解液及びそれを用いたリチウム電池
JP4899862B2 (ja) 2004-03-22 2012-03-21 宇部興産株式会社 非水電解液及びそれを用いたリチウム二次電池
WO2020202661A1 (ja) * 2019-03-29 2020-10-08 日立化成株式会社 リチウムイオン二次電池

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JP2000113906A (ja) * 1998-10-05 2000-04-21 Sunstar Eng Inc 有機電解液
JP2002042865A (ja) * 2000-07-31 2002-02-08 At Battery:Kk 薄型非水系電解液二次電池
JP2002110232A (ja) * 2000-09-29 2002-04-12 Yuasa Corp 非水電解液およびこれを用いたリチウム電池
JP4899862B2 (ja) 2004-03-22 2012-03-21 宇部興産株式会社 非水電解液及びそれを用いたリチウム二次電池
JP2007534122A (ja) * 2004-04-20 2007-11-22 デグサ ゲーエムベーハー 電解液組成物並びに電気化学的なエネルギー貯蔵系用の電解液材料としてのその使用
WO2010018814A1 (ja) * 2008-08-12 2010-02-18 宇部興産株式会社 非水電解液及びそれを用いたリチウム電池
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Publication number Priority date Publication date Assignee Title
WO2026070996A1 (ja) * 2024-09-26 2026-04-02 パナソニックＩｐマネジメント株式会社 二次電池用非水電解質および二次電池
WO2026070997A1 (ja) * 2024-09-26 2026-04-02 パナソニックＩｐマネジメント株式会社 二次電池用非水電解質および二次電池
WO2026070998A1 (ja) * 2024-09-26 2026-04-02 パナソニックＩｐマネジメント株式会社 二次電池用非水電解質および二次電池

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