WO2018230238A1 - 半固体電解質、電極、半固体電解質層付き電極、および二次電池 - Google Patents

半固体電解質、電極、半固体電解質層付き電極、および二次電池 Download PDF

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WO2018230238A1
WO2018230238A1 PCT/JP2018/018977 JP2018018977W WO2018230238A1 WO 2018230238 A1 WO2018230238 A1 WO 2018230238A1 JP 2018018977 W JP2018018977 W JP 2018018977W WO 2018230238 A1 WO2018230238 A1 WO 2018230238A1
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negative electrode
semi
solid electrolyte
electrode
weight
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PCT/JP2018/018977
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French (fr)
Japanese (ja)
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篤 宇根本
克 上田
敦史 飯島
明秀 田中
純 川治
奥村　壮文
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株式会社日立製作所
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Priority to JP2019525229A priority Critical patent/JP6875522B2/ja
Priority to CN201880023968.2A priority patent/CN110521049B/zh
Priority to KR1020197029374A priority patent/KR102272029B1/ko
Publication of WO2018230238A1 publication Critical patent/WO2018230238A1/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
    • H01M10/056—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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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
    • H01M2300/0045—Room temperature molten salts comprising at least one organic ion
    • 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
    • H01M2300/0085—Immobilising or gelification of electrolyte
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a semi-solid electrolyte, an electrode, an electrode with a semi-solid electrolyte layer, and a secondary battery.
  • Patent Document 1 discloses a positive electrode containing a positive electrode active material capable of inserting or removing anions, a negative electrode containing a negative electrode active material capable of inserting or removing cations, A non-aqueous electrolyte storage element comprising a non-aqueous electrolyte obtained by dissolving an electrolyte salt in an aqueous solvent, wherein the non-aqueous solvent comprises 85.0-99.9% by weight of chain carbonate with respect to the total amount of the non-aqueous solvent.
  • non-aqueous electrolyte wherein the cyclic carbonate contains at least fluorinated cyclic carbonate, and the concentration of the electrolyte salt in the non-aqueous electrolyte is 2 mol / L or more
  • a power storage element is disclosed.
  • the present invention aims to improve the life of a secondary battery.
  • ⁇ Described in this specification is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.
  • the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value described in another stepwise manner.
  • the upper limit value or the lower limit value of the numerical ranges described in this specification may be replaced with the values shown in the examples.
  • a lithium ion secondary battery is an electrochemical device that can store or use electrical energy by occlusion / release of lithium ions to and from an electrode in a nonaqueous electrolyte. This is called by another name of a lithium ion battery, a non-aqueous electrolyte secondary battery, and a non-aqueous electrolyte secondary battery, and any battery is a subject of the present invention.
  • the technical idea of the present invention can be applied to sodium ion secondary batteries, magnesium ion secondary batteries, aluminum ion secondary batteries and the like in addition to lithium ion secondary batteries.
  • FIG. 1 is an external view of a secondary battery according to an embodiment of the present invention.
  • FIG. 2 is a cross-sectional view of a secondary battery according to an embodiment of the present invention.
  • 1 and FIG. 2 are stacked secondary batteries, and the secondary battery 1000 includes a positive electrode 100, a negative electrode 200, an outer package 500, and a semi-solid electrolyte layer 300.
  • the outer package 500 houses the semi-solid electrolyte layer 300, the positive electrode 100, and the negative electrode 200.
  • the material of the outer package 500 can be selected from materials that are corrosion resistant to the nonaqueous electrolyte, such as aluminum, stainless steel, and nickel-plated steel.
  • the present invention can also be applied to a wound secondary battery.
  • an electrode body 400 including a positive electrode 100, a semi-solid electrolyte layer 300, and a negative electrode 200 is laminated.
  • the positive electrode 100 or the negative electrode 200 may be referred to as an electrode or a secondary battery electrode.
  • the positive electrode 100, the negative electrode 200, or the semi-solid electrolyte layer 300 may be referred to as a secondary battery sheet.
  • a structure in which the semi-solid electrolyte layer 300 and the positive electrode 100 or the negative electrode 200 are integrated may be referred to as an electrode with a semi-solid electrolyte layer.
  • the electrode with a semi-solid electrolyte layer has a semi-solid electrolyte layer containing a semi-solid electrolyte and an electrode, and the electrode is preferably a negative electrode.
  • the positive electrode 100 has a positive electrode current collector 120 and a positive electrode mixture layer 110.
  • a positive electrode mixture layer 110 is formed on both surfaces of the positive electrode current collector 120.
  • the negative electrode 200 includes a negative electrode current collector 220 and a negative electrode mixture layer 210. Negative electrode mixture layers 210 are formed on both surfaces of the negative electrode current collector 220.
  • the positive electrode mixture layer 110 or the negative electrode mixture layer 210 may be referred to as an electrode mixture layer, and the positive electrode current collector 120 or the negative electrode current collector 220 may be referred to as an electrode current collector.
  • the positive electrode current collector 120 has a positive electrode tab portion 130.
  • the negative electrode current collector 220 has a negative electrode tab portion 230.
  • the positive electrode tab portion 130 or the negative electrode tab portion 230 may be referred to as an electrode tab portion.
  • An electrode mixture layer is not formed on the electrode tab portion. However, an electrode mixture layer may be formed on the electrode tab portion as long as the performance of the secondary battery 1000 is not adversely affected.
  • the positive electrode tab portion 130 and the negative electrode tab portion 230 protrude to the outside of the outer package 500, and the plurality of protruding positive electrode tab portions 130 and the plurality of negative electrode tab portions 230 are bonded together by, for example, ultrasonic bonding. Thus, a parallel connection is formed in the secondary battery 1000.
  • the present invention can also be applied to a bipolar secondary battery in which an electrical series connection is configured in the secondary battery 1000.
  • the positive electrode mixture layer 110 includes a positive electrode active material, a positive electrode conductive agent, and a positive electrode binder.
  • the negative electrode mixture layer 210 includes a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder.
  • the semi-solid electrolyte layer 300 has a semi-solid electrolyte binder and a semi-solid electrolyte.
  • a semi-solid electrolyte includes particles and a semi-solid electrolyte.
  • the positive electrode active material or the negative electrode active material may be referred to as an electrode active material
  • the positive electrode conductive agent or the negative electrode conductive agent may be referred to as an electrode conductive agent
  • the positive electrode binder or the negative electrode binder may be referred to as an electrode binder.
  • the pores of the electrode mixture layer may be filled with a semisolid electrolyte.
  • the semi-solid electrolyte is injected into the secondary battery 1000 from the vacant side or the injection hole of the outer package 500, and the semi-solid electrolyte is filled in the pores of the electrode mixture layer.
  • particles contained in the semisolid electrolyte are not required, and particles such as an electrode active material and an electrode conductive agent in the electrode mixture layer function as particles, and these particles hold the semisolid electrolyte.
  • a slurry in which the semisolid electrolyte, the electrode active material, the electrode conductive agent, and the electrode binder are mixed is prepared, and the prepared slurry is collected into the electrode current collector.
  • methods such as applying together on the body.
  • the semi-solid electrolyte used for forming the semi-solid electrolyte layer 300 includes a semi-solid electrolyte solvent in which an electrolyte salt such as a lithium salt is dissolved in an ether solvent or an ionic liquid, a negative electrode interface additive, and an optional low-viscosity organic solvent. It is a material in which a semi-solid electrolyte and particles such as SiO 2 are mixed.
  • the semi-solid electrolyte layer 300 serves as a medium for transmitting lithium ions between the positive electrode 100 and the negative electrode 200 and also serves as an electronic insulator, thereby preventing a short circuit between the positive electrode 100 and the negative electrode 200.
  • a separator such as a microporous membrane may be used for the semisolid electrolyte layer 300.
  • the separator polyolefin such as polyethylene or polypropylene, glass fiber, or the like can be used.
  • the semi-solid electrolyte is applied to the semi-solid electrolyte layer 300 by injecting the semi-solid electrolyte into the secondary battery 1000 from the vacant side or the injection hole of the outer package 500. Filled.
  • the semi-solid electrolyte may be contained in only one or two or more of the positive electrode 100, the negative electrode 200, and the semi-solid electrolyte layer 300.
  • the electrode conductive agent improves the conductivity of the electrode mixture layer.
  • As the electrode conductive agent ketjen black, acetylene black and the like are preferably used, but are not limited thereto.
  • the electrode binder binds an electrode active material or an electrode conductive agent in the electrode.
  • the electrode binder include, but are not limited to, styrene-butadiene rubber, carboxymethyl cellulose, polyvinylidene fluoride (PVDF), and a mixture thereof.
  • ⁇ Positive electrode active material> In the positive electrode active material exhibiting a noble potential, lithium ions are desorbed during the charging process, and lithium ions desorbed from the negative electrode active material in the negative electrode mixture layer are inserted during the discharging process.
  • part of oxygen in these materials may be replaced with other elements such as fluorine.
  • chalcogenides such as sulfur, TiS 2 , MoS 2 , Mo 6 S 8 and TiSe 2
  • vanadium oxides such as V 2 O 5
  • halides such as FeF 3 , Fe (MoO 4 ) 3 constituting polyanions
  • quinone organic crystals such as Fe 2 (SO 4 ) 3 and Li 3 Fe 2 (PO 4 ) 3
  • the amount of lithium or anion in the chemical composition may deviate from the above stoichiometric composition.
  • ⁇ Positive electrode current collector 120> As the positive electrode current collector 120, an aluminum foil having a thickness of 10 to 100 ⁇ m or an aluminum perforated foil having a thickness of 10 to 100 ⁇ m and a hole diameter of 0.1 to 10 mm, an expanded metal, a foam metal plate, etc. are used. In addition to aluminum, stainless steel, titanium, and the like can also be applied. Any positive electrode current collector 120 can be used without being limited by the material, shape, manufacturing method and the like.
  • ⁇ Negative electrode active material> lithium ions are desorbed in the discharging process, and lithium ions desorbed from the positive electrode active material in the positive electrode mixture layer 110 are inserted in the charging process.
  • the negative electrode active material exhibiting a base potential include carbon materials (eg, graphite, graphitizable carbon material, amorphous carbon material, organic crystal, activated carbon, etc.), conductive polymer materials (eg, polyacene).
  • lithium composite oxides eg, lithium titanate: Li 4 Ti 5 O 12 and Li 2 TiO 4
  • metal lithium metals alloyed with lithium (eg, aluminum, silicon) , Tin or the like) and oxides thereof can be used, but are not limited thereto.
  • a copper foil having a thickness of 10 to 100 ⁇ m, a copper perforated foil having a thickness of 10 to 100 ⁇ m and a pore diameter of 0.1 to 10 mm, an expanded metal, a foam metal plate, or the like is used.
  • copper, stainless steel, titanium, nickel, etc. can also be applied.
  • Any negative electrode current collector 220 can be used without being limited by the material, shape, manufacturing method, and the like.
  • An electrode mixture layer is prepared by adhering an electrode slurry in which an electrode active material, an electrode conductive agent, an electrode binder, and an organic solvent are mixed to an electrode current collector by a doctor blade method, a dipping method, a spray method, or the like. Then, an organic solvent is dried and an electrode is produced by press-molding an electrode mixture layer by a roll press.
  • the electrode slurry may contain a semisolid electrolyte or a semisolid electrolyte.
  • a plurality of electrode mixture layers may be laminated on the electrode current collector by performing a plurality of times from application to drying.
  • the thickness of the electrode mixture layer is preferably equal to or greater than the average particle diameter of the electrode active material. If the thickness of the electrode mixture layer is small, the electron conductivity between adjacent electrode active materials may deteriorate.
  • the particles are preferably insulative particles and insoluble in a semi-solid electrolytic solution containing an organic solvent or ionic liquid.
  • oxide inorganic particles such as silica (SiO 2 ) particles, ⁇ -alumina (Al 2 O 3 ) particles, ceria (CeO 2 ) particles, zirconia (ZrO 2 ) particles can be preferably used.
  • a solid electrolyte may be used as the particles.
  • the solid electrolyte include particles of an inorganic solid electrolyte such as an oxide solid electrolyte or a sulfide solid electrolyte.
  • the average primary particle size of the particles is preferably 1 nm to 10 ⁇ m. If the average particle size of the primary particles of the particles is large, the particles may not properly hold a sufficient amount of the semisolid electrolyte, which may make it difficult to form a semisolid electrolyte. Moreover, when the average particle diameter of the primary particle of particle
  • the average primary particle diameter of the particles is more preferably 1 nm to 50 nm, and further preferably 1 nm to 10 nm. The average particle size of the primary particles of the particles can be measured using a known particle size distribution measuring device using a laser scattering method.
  • the semi-solid electrolyte includes a semi-solid electrolyte solvent, an optional low viscosity organic solvent, and a negative electrode interface additive.
  • the semi-solid electrolyte solvent includes an ionic liquid or a mixture of an ether solvent exhibiting similar properties to the ionic liquid and an electrolyte salt.
  • the electrolyte salt may contain a low-viscosity organic solvent instead of the semi-solid electrolyte.
  • An ionic liquid or an ether solvent may be referred to as a main solvent.
  • An ionic liquid is a compound that dissociates into a cation and an anion at room temperature, and maintains a liquid state.
  • the ionic liquid may be referred to as an ionic liquid, a low melting point molten salt or a room temperature molten salt.
  • the semi-solid electrolyte solvent is desirably a low volatility, specifically, a vapor pressure at room temperature of 150 Pa or less from the viewpoint of stability in the air and heat resistance in the secondary battery.
  • the content of the semisolid electrolyte in the electrode mixture layer is preferably 20% by volume to 40% by volume.
  • the content of the semi-solid electrolytic solution is small, there is a possibility that the ion conduction path inside the electrode mixture layer is not sufficiently formed and the rate characteristic is lowered.
  • a semi-solid electrolyte solution may leak from an electrode mixture layer.
  • the ionic liquid is composed of a cation and an anion. Ionic liquids are classified into imidazolium, ammonium, pyrrolidinium, piperidinium, pyridinium, morpholinium, phosphonium, sulfonium, and the like depending on the cation species. Examples of the cation constituting the imidazolium-based ionic liquid include alkyl imidazolium cations such as 1-ethyl-3-methylimidazolium (EMI) and 1-butyl-3-methylimidazolium (BMI).
  • EMI 1-ethyl-3-methylimidazolium
  • BMI 1-butyl-3-methylimidazolium
  • Examples of the cation constituting the ammonium-based ionic liquid include N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium (DEME) and tetraamylammonium, as well as N, N, N- There are alkylammonium cations such as trimethyl-N-propylammonium.
  • Examples of the cation constituting the pyrrolidinium-based ionic liquid include alkylpyrrolidinium cations such as N-methyl-N-propylpyrrolidinium (Py13) and 1-butyl-1-methylpyrrolidinium.
  • Examples of the cation constituting the piperidinium-based ionic liquid include alkylpiperidinium cations such as N-methyl-N-propylpiperidinium (PP13) and 1-butyl-1-methylpiperidinium.
  • Examples of the cation constituting the pyridinium-based ionic liquid include alkylpyridinium cations such as 1-butylpyridinium and 1-butyl-4-methylpyridinium.
  • Examples of the cation constituting the morpholinium-based ionic liquid include alkylmorpholinium such as 4-ethyl-4-methylmorpholinium.
  • Examples of cations constituting the phosphonium-based ionic liquid include alkylphosphonium cations such as tetrabutylphosphonium and tributylmethylphosphonium.
  • Examples of the cation constituting the sulfonium-based ionic liquid include alkylsulfonium cations such as trimethylsulfonium and tributylsulfonium.
  • anion paired with these cations examples include bis (trifluoromethanesulfonyl) imide (TFSI), bis (fluorosulfonyl) imide (FSI), tetrafluoroborate (BF 4 ), hexafluorophosphate (PF 6 ), There are bis (pentafluoroethanesulfonyl) imide (BETI), trifluoromethanesulfonate (triflate), acetate, dimethyl phosphate, dicyanamide, trifluoro (trifluoromethyl) borate and the like. These ionic liquids may be used alone or in combination.
  • Lithium cation and those consisting of the above anions can be used as lithium salts, such as lithium bis (fluorosulfonyl) imide (LiFSI), lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium bis (pentafluoroethane) Examples include, but are not limited to, sulfonyl) imide (LiBETI), lithium tetrafluoroborate (LiBF 4 ), lithium hexafluorophosphate (LiPF 6 ), and lithium triflate. These electrolyte salts may be used alone or in combination.
  • the ether solvent constitutes a solvated ionic liquid together with the electrolyte salt.
  • a symmetric glycol diglyceride represented by a known glyme (RO (CH 2 CH 2 O) n-R ′ (R and R ′ are saturated hydrocarbons, n is an integer)) showing properties similar to ionic liquids.
  • RO CH 2 CH 2 O
  • n-R ′ saturated hydrocarbons, n is an integer
  • tetraglyme tetraethylene dimethyl glycol, G4
  • triglyme triethylene glycol dimethyl ether, G3
  • pentag lime pentag lime
  • pentag lime pentag lime
  • pentag lime pentag lime
  • lithium imide salts such as LiFSI, LiTFSI, and LiBETI can be used, but are not limited thereto.
  • a mixture of an ether solvent and an electrolyte salt may be used alone or in combination.
  • the low viscosity organic solvent lowers the viscosity of the semi-solid electrolyte solvent and improves the ionic conductivity. Since the internal resistance of the semi-solid electrolyte containing the semi-solid electrolyte solvent is large, the internal resistance of the semi-solid electrolyte can be lowered by increasing the ionic conductivity of the semi-solid electrolyte solvent by adding a low viscosity organic solvent. . However, since the semi-solid electrolyte solvent is electrochemically unstable, the decomposition reaction is accelerated with respect to the battery operation, causing the secondary battery 1000 to increase in resistance and decrease in capacity with the repeated operation of the secondary battery 1000. there is a possibility.
  • the cations of the semi-solid electrolyte solvent are inserted into the graphite during the charging reaction, destroying the graphite structure, and the repetitive operation of the secondary battery 1000 may not be possible. There is.
  • the low-viscosity organic solvent is desirably a solvent having a viscosity lower than 140 Pa ⁇ s, which is a viscosity of a mixture of an ether solvent and an electrolyte salt at 25 ° C., for example.
  • Low-viscosity organic solvents include propylene carbonate (PC), trimethyl phosphate (TMP), gamma butyl lactone (GBL), ethylene carbonate (EC), triethyl phosphate (TEP), tris phosphite (2,2,2- Trifluoroethyl) (TFP), dimethyl methylphosphonate (DMMP), and the like. These low-viscosity organic solvents may be used alone or in combination.
  • the above electrolyte salt may be dissolved in a low viscosity organic solvent. From the viewpoint of the capacity retention rate of the secondary battery 1000, EC is desirable as a low viscosity organic solvent.
  • a fluorine-based resin is preferably used as the semi-solid electrolyte binder.
  • the fluorine-based resin polyvinylidene fluoride (PVDF), a copolymer of polyvinylidene fluoride and hexafluoropropylene (P (VDF-HFP)), polytetrafluoroethylene (PTFE), or the like is preferably used.
  • PVDF polyvinylidene fluoride
  • PVDF-HFP copolymer of polyvinylidene fluoride and hexafluoropropylene
  • PTFE polytetrafluoroethylene
  • a semi-solid electrolyte is constituted by supporting or holding the semi-solid electrolyte on the particles.
  • a semi-solid electrolyte solution and particles are mixed at a specific volume ratio, an organic solvent such as methanol is added and mixed to prepare a semi-solid electrolyte slurry, and the slurry is then mixed with a petri dish.
  • a method of obtaining a semi-solid electrolyte powder by distilling off the organic solvent is a method for producing a semi-solid electrolyte.
  • Methods for producing the semi-solid electrolyte layer 300 include a method of compressing a semi-solid electrolyte powder into a pellet using a molding die, a method of adding a semi-solid electrolyte binder to a semi-solid electrolyte powder, and mixing it into a sheet. There is. By adding and mixing semi-solid electrolyte binder powder to the semi-solid electrolyte, a highly flexible sheet-like semi-solid electrolyte layer 300 can be produced.
  • the semi-solid electrolyte layer 300 can be produced by adding and mixing a solution of a binder in which a semi-solid electrolyte binder is dissolved in a dispersion solvent to the semi-solid electrolyte and distilling off the dispersion solvent.
  • the semi-solid electrolyte layer 300 may be produced by applying and drying the above-mentioned semi-solid electrolyte with a binder solution added and mixed on the electrode.
  • the content of the semisolid electrolyte in the semisolid electrolyte layer 300 is desirably 70% by volume to 90% by volume.
  • the interface resistance between the electrode and the semisolid electrolyte layer 300 may increase.
  • the content of the semi-solid electrolyte is large, the semi-solid electrolyte may leak from the semi-solid electrolyte layer 300.
  • ⁇ Negative bulk density> By setting the negative electrode bulk density (hereinafter also simply referred to as negative electrode density or density) to a predetermined value, the battery capacity of the secondary battery 1000 can be improved. Specifically, (negative electrode bulk density (g / cm 3 )) ⁇ ⁇ 0.05042 (negative electrode interface additive weight ratio (%)) 2 +0.4317 (negative electrode interface additive weight ratio (%)) + 0.9032, especially Desirably, (negative electrode bulk density (g / cm 3 )) ⁇ ⁇ 0.076 (weight ratio of negative electrode interface additive (%)) 2 +0.571 (weight ratio of negative electrode interface additive (%)) + 0.6251.
  • the weight ratio of the negative electrode interface additive means the weight ratio of the negative electrode interface additive to the sum of the weight of the semisolid electrolyte and the weight of the applied negative electrode (hereinafter the same).
  • the method for measuring the negative electrode bulk density can be obtained by measuring the weight and thickness of the negative electrode mixture layer 210 applied on the current collector foil. Specifically, it can be obtained by dividing the measured weight of the negative electrode mixture layer 210 by the product of the thickness and area of the negative electrode mixture layer 210.
  • the negative electrode interface additive forms a passive film on the negative electrode surface and suppresses reductive decomposition of the semi-solid electrolyte.
  • Examples of the negative electrode interface additive include vinylene carbonate (VC), lithium bis (oxalate) borate (LiBOB), fluoroethylene carbonate (FEC), and ethylene sulfite. These negative electrode interface additives may be used alone or in combination.
  • the semi-solid electrolyte of the present invention comprises a semi-solid electrolyte solvent, an optional low-viscosity organic solvent and a semi-solid electrolyte solution containing a negative electrode interface additive, and particles, with respect to the sum of the weight of the semi-solid electrolyte and the negative electrode applied. It is used by applying to the negative electrode so that the weight of the negative electrode interface additive is 0.6% to 11.7%. By defining the amount of the negative electrode interface additive relative to the sum of the weight of the semisolid electrolyte and the negative electrode, the stability between the semisolid electrolyte and the interface of the negative electrode 200 containing graphite or the like is improved.
  • the weight ratio of the negative electrode interface additive to the sum of the weight of the semisolid electrolyte and the applied negative electrode (hereinafter referred to as the negative electrode interface additive weight ratio) is 0.6% to 11.7%, particularly 1.7% to 5.8. % Is desirable.
  • the weight ratio of the negative electrode interface additive is small, the interface between the semisolid electrolyte that contributes to the stable operation of the secondary battery 1000 and the negative electrode 200 containing graphite may not be formed, which may reduce the life of the secondary battery 1000.
  • the weight ratio of the negative electrode interface additive is large, there is a possibility that a decomposition reaction is induced on the surface of the positive electrode 100, thereby reducing the Coulomb efficiency and increasing the battery resistance.
  • the weight ratio of the negative electrode interface additive can be determined by determining the weight of the negative electrode interface additive relative to the sum of the weights of the semisolid electrolytes used for the negative electrode 200 and the semisolid electrolyte layer 300.
  • Example 1> ⁇ Preparation of semi-solid electrolyte> Tetraglyme (G4) and lithium bis (trifluoromethanesulfonyl) imide (LiTFSI) were weighed so as to have a molar ratio of 1: 1, charged into a beaker, and mixed until a homogeneous solvent was prepared to produce a lithium glyme complex. .
  • a lithium glyme complex and fumed silica nanoparticles having a particle diameter of 7 nm are weighed so that the volume ratio is 80:20, and further, propylene carbonate (PC) as a low viscosity organic solvent, vinylene carbonate (VC) as a negative electrode interface additive, Methanol was put into a beaker together with a stir bar and stirred at 600 rpm using a stirrer to obtain a uniform mixture. This mixture was put into an eggplant flask and dried for 3 hours at 100 mbar and 60 ° C. using an evaporator. After drying, the powder was passed through a 100 ⁇ m mesh sieve to obtain a powdery semi-solid electrolyte.
  • PC propylene carbonate
  • VC vinylene carbonate
  • PVDF Polyvinylidene fluoride
  • Graphite was used as the negative electrode active material.
  • the negative electrode conductive agent and the negative electrode binder are the same as those of the positive electrode 100. These were weighed and mixed so that the weight ratio was 88: 2: 10 to obtain a negative electrode slurry.
  • This was applied onto a stainless steel foil as the negative electrode current collector 220 and dried at 80 ° C. for 2 hours to remove N-methylpyrrolidone, thereby obtaining a negative electrode sheet.
  • the negative electrode sheet was punched out with a diameter of 13 mm and uniaxially pressed to obtain a negative electrode 200 with a double-side coating amount of 17 mg / cm 2 and a density of 1.6 g / cm 3 . The weight of the obtained negative electrode was measured.
  • the weight ratio of the lithium glyme complex to PC in the obtained semisolid electrolyte layer 300 was 55.5: 44.5.
  • the weight of VC was 0.6% (negative electrode interface additive weight ratio) with respect to the sum of the weight of the semisolid electrolyte and the weight of the negative electrode 200.
  • a positive electrode 100, a negative electrode 200, and a semi-solid electrolyte layer 300 were laminated and sealed in a 2032 type coin cell to obtain a lithium ion secondary battery.
  • Example 1 was performed except that the weight of VC (weight ratio of negative electrode interface additive) with respect to the sum of the weight of the semisolid electrolyte and the negative electrode 200 was changed as shown in FIG.
  • LiBOB Lithium bis (oxalate) borate
  • Example 12 to 14 Example except that fluoroethylene carbonate (FEC) was used as the negative electrode interface additive, and the weight of the FEC relative to the sum of the weight of the semisolid electrolyte and the negative electrode 200 (weight ratio of the negative electrode interface additive) was as shown in FIG. Same as 1.
  • FEC fluoroethylene carbonate
  • Example 15 Ethylene carbonate (EC) is used as the low viscosity organic solvent, vinylene carbonate (VC) is used as the negative electrode interface additive, and the weight ratio of the lithium glyme complex and EC in the semisolid electrolyte layer 300 is as shown in FIG. Example 1 was repeated except that the weight of VC with respect to the sum of the weight of the solid electrolyte and the weight of the negative electrode 200 was 1.7%.
  • EC Ethylene carbonate
  • VC vinylene carbonate
  • the weight ratio of the lithium glyme complex and EC in the semisolid electrolyte layer 300 is as shown in FIG. Example 1 was repeated except that the weight of VC with respect to the sum of the weight of the solid electrolyte and the weight of the negative electrode 200 was 1.7%.
  • Example 1 was performed except that the density of the negative electrode 200, the weight of the semisolid electrolyte, and the weight of VC with respect to the sum of the negative electrode 200 (weight ratio of the negative electrode interface additive) were as shown in FIG.
  • Example 1 was repeated except that no negative electrode interface additive was used.
  • Example 1 was performed except that the weight of VC (weight ratio of negative electrode interface additive) with respect to the sum of the weight of the semisolid electrolyte and the negative electrode 200 was changed as shown in FIG.
  • the measurement voltage range is 2.7 V to 4.2 V
  • the battery is operated in the constant current-constant voltage mode
  • the discharge is operated in the constant current mode
  • the discharge is performed after the first cycle discharge.
  • the capacity (initial discharge capacity) and the discharge capacity after 30 cycle discharge (30 cycle discharge capacity) were measured.
  • FIG. 3 shows the measurement results of Examples and Comparative Examples.
  • Figure 3 shows the value obtained by dividing the initial discharge capacity by the 30-cycle discharge capacity (discharge capacity retention rate). It is considered that the initial discharge capacity strongly influences the battery capacity of the secondary battery 1000, and the discharge capacity maintenance ratio strongly influences the life of the secondary battery 1000. Therefore, the battery capacity evaluation standard was that the initial discharge capacity was 105 (mAh / g) or more, and the life evaluation standard was that the discharge capacity retention rate was 65% or more.
  • the discharge capacity retention rate was a desirable value for any of the examples.
  • the weight ratio of the negative electrode interface additive was 1.7% to 5.8%
  • the low-viscosity solvent was the same, and the 30-cycle discharge capacity was larger than that of the comparative example not including the negative electrode interface additive.
  • the example in which the negative electrode interface additive was added had a larger initial discharge capacity than the comparative example in which the negative electrode interface additive was not added.
  • FIG. 4 shows a relationship diagram between the deterioration coefficient and the negative electrode interface additive weight ratio.
  • the discharge capacity retention rate was plotted against the cycle number 1/2, and the slope was obtained by linear approximation and defined as the degradation coefficient.
  • the deterioration coefficient always takes a negative value, and the smaller the absolute value is, the higher the capacity retention rate is. As shown in FIG.
  • the deterioration factor is -5 (discharge capacity maintenance rate after 100 cycles is 50%) because the negative electrode interface additive weight ratio is 1.3% to 13.9%, and the deterioration factor is -3 (after 100 cycles).
  • the negative electrode interface additive is VC>
  • the weight ratio of the negative electrode interface additive to the sum of the weight of the semisolid electrolyte and the negative electrode 200 is 0.6% to 11.7%
  • Comparative Example 1 that does not include the negative electrode interface additive
  • Comparative Examples 2 and 3 in which the weight ratio of the negative electrode interface additive is 14.6% or more
  • the 30-cycle discharge capacity was large.
  • the weight ratio of the negative electrode interface additive was 0.6% to 5.8% (Examples 1 to 7)
  • the 30-cycle discharge capacity was larger than those of Comparative Examples 1, 2 and 3.
  • the weight ratio of the negative electrode interface additive was 1.7% to 5.8% (Examples 3 to 7)
  • the discharge capacity was as high as 130 mAh / g or more during the battery operation at least 30 times.
  • the weight ratio of the negative electrode interface additive When the weight ratio of the negative electrode interface additive is small, the interface between the semi-solid electrolyte and the negative electrode 200 is not sufficiently stabilized, and the initial discharge capacity is reduced due to partial progress of co-insertion and reductive decomposition of the lithium glyme complex. It is possible. On the other hand, when the weight ratio of the negative electrode interface additive is large, it is considered that VC gradually decomposes on the surface of the positive electrode 100 with the cycle operation to induce high resistance, thereby reducing the discharge capacity.
  • Example 15 where the low-viscosity organic solvent is EC, the initial discharge capacity and 30-cycle discharge capacity were large by setting the weight ratio of the negative electrode interface additive to 1.7%.
  • the negative electrode interface additive is LiBOB>
  • the maximum value of the negative electrode interface additive weight ratio was 1.7%. This is because when the weight ratio is larger than this, the introduced LiBOB may not be completely dissolved in the mixed solvent.
  • the weight ratio of the negative electrode interface additive was 0.6% to 1.7%, the initial discharge capacity and the 30-cycle discharge capacity were larger than those of Comparative Example 1 not including LiBOB.
  • ⁇ Negative electrode interface additive is FEC>
  • the initial discharge capacity was larger than that of Comparative Example 1 containing no FEC, and the 30 cycle discharge capacity was 100 mAh / g or more.
  • the battery capacity depends not only on the negative electrode interface additive weight ratio but also on the negative electrode bulk density. This is because when the negative electrode bulk density is small, the negative electrode 200 becomes thick and the resistance of the secondary battery may increase. Also, when the negative electrode bulk density is large, the gap inside the electrode becomes small, and the negative electrode interface additive does not reach the vicinity of the electrode current collector during the initial charge, so that the decomposition reaction of the semi-solid electrolyte is induced. This is because the resistance of the secondary battery may increase.
  • FIG. 5 shows the relationship between the initial discharge capacity and the negative electrode interface additive weight ratio, with the negative electrode bulk density being constant (1.12 to 1.77 g / cm 3 ) for Examples 16 to 33 and Comparative Examples 4 to 9.
  • the initial discharge capacity was approximated by a quadratic function depending on the negative electrode interface additive weight ratio.
  • the constant term of the approximate curve depended on the negative electrode bulk density.
  • FIG. 6 shows the relationship between the negative electrode bulk density and the initial discharge capacity for Examples 16 to 33 and Comparative Examples 4 to 9, with the negative electrode interface additive weight ratio being constant (0 to 5.8%).
  • the initial discharge capacity was approximated by a straight line having a negative slope with respect to the negative electrode bulk density.
  • the magnitude of the slope of the straight line was dependent on the weight ratio of the negative electrode interface additive.
  • the relationship between the negative electrode bulk density and the negative electrode interface additive weight ratio required to obtain a certain initial discharge capacity Q was determined from the approximate curves and approximate lines obtained from FIGS. 5 and 6, and is shown in FIG. Regardless of the negative electrode bulk density, the initial discharge capacity Q was increased by adding the negative electrode interface additive. In the region indicated by (negative electrode bulk density (g / cm 3 )) ⁇ ⁇ 0.05042 (negative electrode interface additive weight ratio (%)) 2 +0.4317 (negative electrode interface additive weight ratio (%)) + 0.9032
  • the initial discharge capacity Q was 120 mAh / g or more.

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