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
  • H01M10/056—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
  • H01M10/056—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
• • 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 disclosure relates to a method for predicting the effect of an additive on improving the life of a lithium-ion secondary battery, and a method for producing an electrolytic solution.
• Patent Document 1 discloses an electrolytic solution containing a specific siloxane compound in order to improve cycle characteristics and internal resistance characteristics.
• the lithium ion secondary battery By the way, for example, when trying to improve the life of a lithium ion secondary battery by adding an additive, after producing a lithium ion secondary battery containing an electrolyte solution to which each of a number of additives is added, the lithium ion secondary battery By actually measuring the life of the secondary battery, it is necessary to evaluate the effect of each additive on improving the life of the lithium-ion secondary battery. However, it takes a lot of time and effort to make a series of lithium ion secondary battery production and life measurement evaluations for many additives. It is desirable to be able to predict the life-improving effect of the additive on the lithium-ion secondary battery without performing the test.
• the present inventors have found that additives added to an electrolytic solution containing LiPF 6 widely used as a lithium salt cause differences in the 31 P - NMR measurement results of the electrolytic solution. It was found that the effect of improving the life of the lithium ion secondary battery by the additive can be predicted based on the position of the peak derived from.
• One aspect of the present invention is a lithium ion secondary battery containing an electrolyte solution containing LiPF 6 and an additive, a method for predicting the effect of the additive on improving the life of the lithium ion secondary battery, the method comprising LiPF 6 , the first electrolytic solution for measurement containing no additive, and the second electrolytic solution for measurement in which an additive is added to the first electrolytic solution for measurement, are each subjected to 31 P-NMR measurement.
• Another aspect of the present invention is a method for producing an electrolyte, comprising a selection step of selecting an additive, and a preparation step of preparing an electrolyte containing LiPF 6 and the selected additive, wherein the selection
• 31 P-NMR measurement was performed, and in the 31 P-NMR measurement results, the position ⁇ P2 of the peak derived from PF 6 - in the second electrolytic solution for measurement was the same as that of PF 6 - in the first electrolytic solution for measurement.
• This is a method for producing an electrolytic solution in which an additive is selected such that the peak position ⁇ P1 derived from is shifted to the lower magnetic field side.
• One embodiment of the present invention is a method for predicting the life-improving effect of an additive in a lithium-ion secondary battery containing an electrolytic solution containing LiPF 6 and an additive.
• the additive for which the effect of improving the life of the lithium ion secondary battery is predicted is also referred to as "additive X”.
• This method includes a first measurement electrolyte solution containing LiPF 6 and no additive X, and a second measurement electrolyte solution in which an additive X is added to the first measurement electrolyte solution. For each, a measurement step of performing 31 P-NMR measurement is provided.
• the first measurement electrolyte and the second measurement electrolyte are prepared.
• the first electrolyte for measurement contains, for example, LiPF 6 and a non-aqueous solvent.
• the second electrolytic solution for measurement contains, for example, LiPF 6 , additive X, and non-aqueous solvent.
• the composition of the second electrolytic solution for measurement is the same as the composition of the first electrolytic solution for measurement, except for the presence or absence of the additive X.
• the additive X is not particularly limited, and any additive that is desired to predict the effect of improving the life of the lithium ion secondary battery can be used.
• the additive X in one embodiment, may be a compound having a Si—F bond, more specifically, for example, a compound represented by the following formula (1).
• R 1 and R 2 each independently represent a monovalent hydrocarbon group optionally substituted with a halogen atom or a halogen atom
• R 3 represents an alkylene group
• R 4 represents a hydrogen atom , a halogen atom, or a monovalent organic group.
• the "monovalent hydrocarbon group optionally substituted with a halogen atom” represented by R 1 and R 2 is an unsubstituted monovalent hydrocarbon group, or a hydrogen atom in the monovalent hydrocarbon group is a monovalent hydrocarbon group in which at least one of is substituted with a halogen atom (hereinafter also referred to as "halogen-substituted monovalent hydrocarbon group").
• a monovalent hydrocarbon group may be, for example, an alkyl group or an aryl group.
• the alkyl group may be linear or branched.
• the number of carbon atoms in the monovalent hydrocarbon group may be 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, or 6 or more, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, or 2 or less.
• the halogen atom in the halogen-substituted monovalent hydrocarbon group may be, for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, a fluorine atom, a chlorine atom, or a fluorine atom.
• the number of halogen atoms in the halogen-substituted monovalent hydrocarbon group may be 1 or more, 2 or more, 3 or more, or 4 or more, and may be 6 or less, 5 or less, 4 or less, 3 or less, or 2 or less. you can
• a halogen atom represented by R 1 and R 2 may be, for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and may be a fluorine atom, a chlorine atom, or a fluorine atom.
• the alkylene group represented by R 3 may be linear or branched.
• the number of carbon atoms in the alkylene group may be 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, or 6 or more, and 12 or less, 11 or less, 10 or less, 9 or less, 8 or less, 7 or less, 6 or less. , 5 or less, 4 or less, or 3 or less.
• a halogen atom represented by R4 may be, for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and may be a fluorine atom, a chlorine atom, or a fluorine atom.
• the monovalent organic group represented by R 4 may be, for example, a monovalent organic group containing a silicon atom, or a silyl group.
• a silyl group is represented, for example, by the following formula (2).
• R 11 to R 13 each independently represent a monovalent hydrocarbon group optionally substituted with a halogen atom or a halogen atom.
• the “monovalent hydrocarbon group optionally substituted with a halogen atom” represented by R 11 to R 13 is an unsubstituted monovalent hydrocarbon group or a halogen-substituted monovalent hydrocarbon group.
• a monovalent hydrocarbon group may be, for example, an alkyl group or an aryl group.
• the alkyl group may be linear or branched.
• the number of carbon atoms in the monovalent hydrocarbon group may be 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, or 6 or more, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, or 2 or less.
• the halogen atom in the halogen-substituted monovalent hydrocarbon group may be, for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, a fluorine atom, a chlorine atom, or a fluorine atom.
• the number of halogen atoms in the halogen-substituted monovalent hydrocarbon group may be 1 or more, 2 or more, 3 or more, or 4 or more, and may be 6 or less, 5 or less, 4 or less, 3 or less, or 2 or less. you can
• a halogen atom represented by R 11 to R 13 may be, for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and may be a fluorine atom, a chlorine atom, or a fluorine atom.
• the monovalent organic group represented by R4 may be, for example, a monovalent organic group containing a sulfur atom.
• a monovalent organic group containing a sulfur atom may be, for example, a group represented by the following formula (3).
• R 14 represents an alkyl group.
• Alkyl groups may be linear or branched. The number of carbon atoms in the alkyl group may be 1 or more and 3 or less.
• Alkyl groups can be, for example, methyl, ethyl, or propyl groups.
• a monovalent organic group containing a sulfur atom may be, for example, a group represented by the following formula (4). wherein R 15 may be an alkyl group.
• the alkyl group may be the same as the alkyl group represented by R 14 described above.
• a monovalent organic group containing a sulfur atom may be, for example, a group represented by the following formula (5). wherein R 16 may be an alkyl group.
• the alkyl group may be the same as the alkyl group represented by R 14 described above.
• the monovalent organic group represented by R4 may be, for example, a monovalent organic group containing a nitrogen atom.
• a monovalent organic group containing a nitrogen atom may be, for example, a group represented by the following formula (6).
• R 17 and R 18 each independently represent a hydrogen atom or an alkyl group.
• the alkyl groups represented by R 17 and R 18 may be the same as the alkyl groups represented by R 14 described above.
• the monovalent organic group represented by R4 may be, for example, a monovalent organic group containing an oxygen atom (excluding a monovalent organic group containing a sulfur atom in addition to an oxygen atom).
• a monovalent organic group containing an oxygen atom may be, for example, a group represented by the following formula (7).
• R 19 represents an alkyl group. Alkyl groups may be linear or branched. The number of carbon atoms in the alkyl group may be 1 or more and 5 or less.
• a monovalent organic group containing an oxygen atom may be, for example, a group represented by the following formula (8).
• R20 represents an alkyl group.
• Alkyl groups may be linear or branched.
• the number of carbon atoms in the alkyl group may be 1 or more and 5 or less.
• a monovalent organic group containing an oxygen atom may be, for example, a group represented by the following formula (9).
• R21 represents an alkyl group.
• Alkyl groups may be linear or branched.
• the number of carbon atoms in the alkyl group may be 1 or more and 5 or less.
• a monovalent organic group containing an oxygen atom may be, for example, a group represented by the following formula (10).
• R22 represents an alkyl group.
• Alkyl groups may be linear or branched.
• the number of carbon atoms in the alkyl group may be 1 or more and 5 or less.
• a non-aqueous solvent is a non-aqueous solvent that can dissolve LiPF 6 .
• Non-aqueous solvents include, for example, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ⁇ -butyl lactone, acetonitrile, 1,2-dimethoxyethane, dimethoxymethane, tetrahydrofuran, dioxolane, methylene chloride, methyl acetate, etc. can be
• the content (concentration) of each component in the first electrolytic solution for measurement and the second electrolytic solution for measurement is not particularly limited.
• the concentration of LiPF 6 in the first and second measurement electrolytes may be, for example, 0.5 mol/L or more and 1.5 mol/L or less.
• the content of the additive X in the second electrolytic solution for measurement may be, for example, 0.1 mol or more and may be 1 mol or less with respect to 1 mol of LiPF 6 content.
• the first electrolytic solution for measurement and the second electrolytic solution for measurement may further contain additives other than additive X in common.
• additives are not particularly limited, and additives used in electrolyte solutions for lithium ion secondary batteries are appropriately used.
• Other additives include, for example, a cyclic compound having a carbon-carbon double bond (cyclic carbonate having a carbon-carbon double bond, etc.), a cyclic compound having a fluorine atom (cyclic carbonate having a fluorine atom, etc.), sulfur cyclic compounds having atoms (cyclic sulfonate compounds, etc.), nitrile compounds, and the like.
• 31 P-NMR measurement is performed on each of the prepared first measurement electrolyte solution and second measurement electrolyte solution.
• 31 P-NMR measurement is performed, for example, according to the following procedure.
• TPP triphenyl phosphate
• the first electrolytic solution for measurement is placed in the inner tube of a coaxial NMR tube (for example, 5 mm ⁇ coaxial NMR tube SP-404 (manufactured by Shigemi Co., Ltd.)), and the above standard sample is placed in the outer tube. Deploy.
• the 31 P-NMR measurement of the first electrolytic solution for measurement is performed with an NMR device (eg, Ascend TM 400 manufactured by Bruker) with 128 integration times in the same manner as the measurement of the standard sample. After measurement, adjust the TPP peak to -17.95 ppm.
• the position ⁇ P1 of the peak derived from PF 6 ⁇ in the first electrolytic solution for measurement and the position ⁇ P2 of the peak derived from PF 6 ⁇ in the second electrolytic solution for measurement. the magnitude of the life-improving effect of additive X is determined. Specifically, as demonstrated in Examples described later, the position ⁇ P2 of the peak derived from PF 6 - in the second electrolytic solution for measurement is the same as that of PF 6 - in the first electrolytic solution for measurement.
• the position of the peak derived from - is shifted to the low magnetic field side from the position ⁇ P1 , it can be judged that the life improvement effect of the additive X is large.
• the position ⁇ P2 of the peak derived from PF 6 ⁇ in the second electrolytic solution for measurement shifts to the higher magnetic field side than the position ⁇ P1 of the peak derived from PF 6 ⁇ in the first electrolytic solution for measurement. If it does or if it does not shift, it can be determined that the effect of the additive X on improving the life is small.
• the peak position ⁇ P2 is likely to shift to the lower magnetic field side than the peak position ⁇ P1 . This is believed to be due to the fact that PF 6 - coordinates with Si—F in the additive X, thereby reducing the electron density of P in PF 6 - .
• Another embodiment of the present invention is a method for producing an electrolyte, comprising a selection step of selecting an additive, and a preparation step of preparing an electrolyte containing LiPF 6 and the selected additive.
• a first measurement electrolyte solution containing LiPF 6 and not containing additive X, and an additive X added to the first measurement electrolyte solution were prepared.
• 31 P-NMR measurement is performed on each of the added second measuring electrolytes.
• the position ⁇ P2 of the peak derived from PF 6 - in the second electrolytic solution for measurement is the peak derived from PF 6 - in the first electrolytic solution for measurement.
• the additive X is selected such that the position ⁇ P1 of ⁇ is shifted to the lower magnetic field side.
• an electrolytic solution containing LiPF 6 and selected additive X is prepared.
• the electrolytic solution may further contain the same non-aqueous solvent as described above, and may further contain other additives similar to those described above.
• the concentration of LiPF 6 in the electrolyte may be, for example, 0.5 mol/L or more, 0.7 mol/L or more, or 0.8 mol/L or more, and 1.5 mol/L or less, 1.3 mol/L. or less, or 1.2 mol/L or less.
• the content of the additive X in the electrolytic solution is appropriately selected according to the type of the additive X. For example, based on the total amount of the electrolytic solution, 0.1% by mass or more, 0.3% by mass or more, 0.5% by mass or more. % by mass or more, 0.7% by mass or more, 1% by mass or more, 2% by mass or more, 3% by mass or more, 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more , 50% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, 15% by mass or less, 10% by mass or less, 9% by mass or less, 8% by mass or less, 7% by mass or less, 6% by mass or less , or 5% by mass or less.
• the additive X having a large effect of improving the life of the lithium ion secondary battery can be easily selected in the selection process, so that the electrolyte solution having a large effect of improving the life of the lithium ion secondary battery can be efficiently produced. .
• EC ethylene carbonate
• EMC ethyl methyl carbonate
• DMC dimethyl carbonate
• additives X1 to X3 were added to the above-mentioned first electrolytic solution for measurement to prepare three types of second electrolytic solutions for measurement 1 to 3, respectively.
• the amount of additives X1 to X3 added is 0.25 mmol each (in terms of mass, additive X1: 0.034 g, additive X2: 0.050 g, additive X3: 0.027 g).
• Additive X1 a compound represented by the following formula (X1)
• Additive X2 a compound represented by the following formula (X2)
• Additive X3 fluoroethylene carbonate (FEC)
• ⁇ 31 P-NMR measurement> As a standard sample for 31 P-NMR measurement, a solution was prepared by dissolving triphenyl phosphate (TPP) in heavy acetone to a concentration of 0.0485 mol/L. 31 P-NMR of this standard sample was measured with Ascend TM 400 manufactured by Bruker with 128 integration times. The TPP peak was adjusted to ⁇ 17.95 ppm and used as the reference peak.
• TPP triphenyl phosphate
• each of the first measurement electrolyte solution and the second measurement electrolyte solution 1 to 3 is placed in the inner tube of a 5 mm ⁇ coaxial NMR tube SP-404 (manufactured by Shigemi Co., Ltd.), and the outer The above standard sample was placed in the tube of .
• the preparation of each of the above electrolytic solutions and placement in the 5 mm ⁇ coaxial NMR tube were carried out in a glove box under an argon atmosphere with a dew point of ⁇ 80° C. or lower.
• the 31 P-NMR measurement of the first measuring electrolyte and the second measuring electrolytes 1 to 3 was performed with Ascend TM 400 manufactured by Bruker with 128 times of integration in the same manner as the measurement of the standard sample. After measurement, the TPP peak was adjusted to -17.95 ppm. Seven peaks of P derived from PF 6 - appeared from about -125 ppm to -165 ppm, and the central peak among them was designated as the central peak of PF 6 - . Table 1 shows the central peak position of PF 6 ⁇ in each of the first measuring electrolyte and the second measuring electrolytes 1 to 3.
• This slurry was applied on a positive electrode current collector (aluminum foil with a thickness of 15 ⁇ m), dried at 120° C., and then rolled to obtain a positive electrode active material having a coating amount on one side of 200 g/m 2 and a mixture density of 2.8 g/cm 3 . A material layer was formed. As a result, a rectangular positive electrode laminate having a positive electrode active material layer formed on one surface of the positive electrode current collector was obtained.
• a slurry was prepared by mixing pure water so that 98 parts by mass of graphite (negative electrode active material) and 2 parts by mass of CMC-SBR were uniformly dispersed. This slurry was applied on a negative electrode current collector (copper foil with a thickness of 10 ⁇ m), dried at 80° C., and then rolled to obtain a negative electrode active material having a coating amount on one side of 102 g/m 2 and a mixture density of 1.6 g/cm 3 . formed a layer. As a result, a rectangular negative electrode laminate having a negative electrode active material layer formed on one surface of the negative electrode current collector was obtained.
• the positive electrode was cut into a square of 13.5 cm 2 , sandwiched between polyethylene porous sheets (trade name: Hipore (registered trademark), manufactured by Asahi Kasei Corporation, thickness 30 ⁇ m) as a separator, and further cut into a square of 14.3 cm 2 .
• An electrode group was produced by stacking the negative electrodes cut into pieces. This electrode group was accommodated in a container (battery outer package) formed of an aluminum laminate film (trade name: aluminum laminate film, manufactured by Dai Nippon Printing Co., Ltd.). Next, 1 mL of the electrolytic solution was added into the container, and the container was heat-sealed to produce a secondary battery 1 for evaluation.
• a reference secondary battery was fabricated in the same manner as evaluation secondary battery 1, except that 3.4% by mass of additive X1 was not added in the preparation of the electrolytic solution.
• the cycle characteristics of each secondary battery were evaluated by a cycle test in which charge/discharge was repeated.
• the charging pattern under an environment of 45° C., the produced secondary battery was subjected to constant current charging at a current value of 0.5 C up to an upper limit voltage of 4.2 V, and then to constant voltage charging at 4.2 V.
• a charge termination condition was a current value of 0.05C.
• the discharge constant current discharge was performed at 1C to 2.7V, and the discharge capacity was obtained.
• This series of charging/discharging was repeated 500 cycles, and the discharge capacity was measured each time charging/discharging was performed. Taking the discharge capacity after the first charge/discharge cycle as 100%, the relative value of the discharge capacity at the time of 500 cycles (discharge capacity ratio) was determined.
• Table 2 shows the evaluation results of the cycle characteristics of the evaluation secondary batteries 1 to 3.
• Table 2 also shows the results of the 31 P-NMR measurement (center peak position of PF 6 ⁇ ) for the additives X1 to X3 used in each of the secondary batteries 1 to 3 for evaluation. It is shown as the magnitude of the shift from the central peak position of PF 6 ⁇ of one measuring electrolyte (no additive).

Landscapes

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

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=84800712

Family Applications (1)

Country Status (2)

Citations (3)

• 2022
  • 2022-07-04 WO PCT/JP2022/026617 patent/WO2023282233A1/ja not_active Ceased
  • 2022-07-04 JP JP2023533123A patent/JPWO2023282233A1/ja active Pending

Patent Citations (3)

Also Published As

Similar Documents

Legal Events