WO2018110133A1 - Secondary battery electrode, secondary battery, and method for producing same - Google Patents

Secondary battery electrode, secondary battery, and method for producing same Download PDF

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Publication number
WO2018110133A1
WO2018110133A1 PCT/JP2017/039685 JP2017039685W WO2018110133A1 WO 2018110133 A1 WO2018110133 A1 WO 2018110133A1 JP 2017039685 W JP2017039685 W JP 2017039685W WO 2018110133 A1 WO2018110133 A1 WO 2018110133A1
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Prior art keywords
electrode
secondary battery
conductive agent
agent
positive electrode
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PCT/JP2017/039685
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French (fr)
Japanese (ja)
Inventor
克 上田
純 川治
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株式会社日立製作所
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Priority to CN201780075754.5A priority Critical patent/CN110121799B/en
Priority to JP2018556242A priority patent/JP6916815B2/en
Publication of WO2018110133A1 publication Critical patent/WO2018110133A1/en

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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
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers

Definitions

  • the present invention relates to an electrode for a secondary battery, a secondary battery, and a method for producing them.
  • Lithium ion secondary batteries capable of realizing high voltage and high energy density are used in a wide range of applications from in-vehicle use such as electric vehicles and hybrid vehicles to personal computers and portable communication devices.
  • the central issue in the research and development of lithium ion secondary batteries is to further improve the energy density and improve the safety and reliability of the battery itself.
  • development of solid electrolyte membranes having high lithium ion conductivity has been vigorously advanced.
  • a typical example of the solid electrolyte is a solid electrolyte using an oxide or sulfide-based ceramic having lithium ion conductivity. This is characterized by high fire resistance because it does not contain the electrolyte itself.
  • electrode material particles having an average particle diameter of Da, solid particles having an average particle diameter of Db, and an ionic liquid are dispersed in a liquid medium to obtain a dispersion, and the dispersion is placed on a support.
  • a method is disclosed.
  • acetylene black is used in the electrode material particles.
  • the surface potential of the conductive material such as acetylene black is negative, lithium ions in the ionic liquid are adsorbed on the conductive material, and the secondary material is secondary. The ionic conductivity of the battery electrode may be reduced.
  • An object of the present invention is to improve the ionic conductivity of an electrode for a secondary battery.
  • a secondary battery that includes an electrode active material, an electrode conductive agent, and an ionic conductive material, the ionic conductive material is held by the electrode conductive agent, a coating is formed on the surface of the electrode conductive agent, and the surface potential of the electrode conductive agent is positive Electrode.
  • the ionic conductivity of the secondary battery electrode can be improved. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.
  • a lithium ion secondary battery will be described as an example of an all-solid battery, but the technical idea of the present invention is not only a lithium ion secondary battery, but also a sodium ion secondary battery, a magnesium ion secondary battery, The present invention can also be applied to an aluminum ion secondary battery.
  • FIG. 1 is a cross-sectional view of a secondary battery according to an embodiment of the present invention.
  • the all-solid battery 100 includes a positive electrode 70, a negative electrode 80, a battery case 30, and a solid electrolyte layer 50.
  • the battery case 30 accommodates the solid electrolyte layer 50, the positive electrode 70, and the negative electrode 80.
  • the material of the battery case 30 can be selected from materials that are corrosion resistant to non-aqueous electrolytes, such as aluminum, stainless steel, and nickel-plated steel.
  • an electrode body composed of the positive electrode 70, the solid electrolyte layer 50, and the negative electrode 80 is laminated.
  • the positive electrode 70 includes the positive electrode current collector 10 and the positive electrode mixture layer 40.
  • a positive electrode mixture layer 40 is formed on both surfaces of the positive electrode current collector 10.
  • the negative electrode 80 includes a negative electrode current collector 20 and a negative electrode mixture layer 60. Negative electrode mixture layers 60 are formed on both surfaces of the negative electrode current collector 20.
  • the positive electrode current collector 10 and the negative electrode current collector 20 protrude outside the battery case 30, and the plurality of protruding positive electrode current collectors 10 and the plurality of negative electrode current collectors 20 are bonded together by, for example, ultrasonic bonding. As a result, a parallel connection is formed in the all solid state battery 100.
  • FIG. 2 is a cross-sectional view of a secondary battery according to an embodiment of the present invention.
  • FIG. 2 includes a plurality of positive electrode mixture layers 40, negative electrode mixture layers 60, and solid electrolyte layers 50. Outermost positive electrode mixture layer 40 and negative electrode mixture layer 60 in bipolar all solid state battery 200 in the figure are connected to positive electrode current collector 10 and negative electrode current collector 20. Further, an interconnector 90 as a current collector is disposed between the positive electrode mixture layer 40 and the negative electrode mixture layer 60 that are adjacent to each other in the battery case 30. The interconnector 90 has high electronic conductivity, no ionic conductivity, and the surface in contact with the negative electrode mixture layer 60 and the positive electrode mixture layer 40 does not exhibit a redox reaction depending on the respective potentials. Can be mentioned.
  • Materials that can be used for the interconnector 90 include materials that can be used for the following positive electrode current collector 10 and negative electrode current collector 20. Specific examples include aluminum foil and SUS foil. Alternatively, the positive electrode current collector 10 and the negative electrode current collector 20 can be bonded together by clad molding and electron conductive slurry.
  • FIG. 3 is a cross-sectional view of a main part of the secondary battery according to the embodiment of the present invention.
  • the positive electrode mixture layer 40 includes a positive electrode active material 42, a positive electrode conductive agent 43, a positive electrode binder for binding them, arbitrary inorganic particles 51, and an ionic conductive material 52.
  • the negative electrode mixture layer 60 includes a negative electrode active material 62, a negative electrode conductive agent 63, a negative electrode binder for binding them, arbitrary inorganic particles 51, and an ionic conductive material 52.
  • the solid electrolyte layer 50 has an electrolyte binder 53 and a solid electrolyte 55.
  • the solid electrolyte 55 includes inorganic particles 51 and an ion conductive material 52.
  • the positive electrode 70 and the negative electrode 80 are electrodes (secondary battery electrodes), the positive electrode conductive agent 43 or the negative electrode conductive agent 63 is an electrode conductive material, the positive electrode binder or the negative electrode binder is an electrode binder, and the positive electrode active material 42 or the negative electrode active material 62 is an electrode active material.
  • the positive electrode active material 42 or the negative electrode active material 62 is an electrode active material.
  • Electrode binder As the electrode binder, styrene-butadiene rubber, carboxymethyl cellulose, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), poly (vinylidene fluoride-co-hexafluoropropylene) copolymer (PVdF-HFP) ) And mixtures thereof, but are not limited thereto.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PVdF-HFP poly (vinylidene fluoride-co-hexafluoropropylene) copolymer
  • a lithium composite oxide containing a transition metal is preferable, and specific examples include LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , LiMnO 3 , LiMn 2 O 3 , LiMnO 2 , Li 4.
  • Li 2 Mn 3 MO 8 Fe, Co, Ni, Cu, Zn
  • Electrode conductive agent manufactured from conductive fibers (for example, vapor-grown carbon, carbon nanotubes, pitch (byproducts such as petroleum, coal, coal tar, etc.) and carbonized at high temperature, and acrylic fibers. Carbon fiber etc.) are preferably used.
  • the electrode conductive agent is a material having a lower electrical resistivity than the electrode active material, and does not oxidize and dissolve at the charge / discharge potential of the electrode (usually 2.5 to 4.5 V in the case of the positive electrode 70). May be used.
  • corrosion resistant metals such as titanium and gold
  • carbides such as SiC and WC
  • nitrides such as Si3N4 and BN
  • a carbon material having a high specific surface area for example, carbon black or activated carbon
  • an ionic conductive material 52 is included in the electrode. At this time, similarly to the inorganic particles 51, the ionic conductive material 52 is supported on the electrode conductive agent, whereby a semi-solid semi-solid electrolyte is formed.
  • the treatment of keeping the surface of the electrode conductive agent at a positive potential is performed. Since the surface of the electrode conductive agent such as carbon has a negative potential, lithium ions having a positive charge are adsorbed on the surface of the electrode conductive agent. Since the adsorbed lithium ions can no longer contribute to charge transport, the ionic conductivity inside the electrode decreases as a result. On the other hand, if the surface of the electrode conductive agent is a positive potential, lithium ion adsorption to the surface of the electrode conductive agent is suppressed, so that a decrease in ion conduction inside the electrode can be suppressed.
  • a surface treatment agent is introduced.
  • the coating agent is formed on the entire surface or part of the electrode conductive agent.
  • surface treatment agents include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 4-aminobutyltriethoxysilane, aminophenyltrimethoxysilane, 3-aminophenyltrimethoxysilane, and m-aminophenyl.
  • a surface treatment agent at least one of an amino group and a phosphine group is introduced onto the surface of the electrode conductive agent.
  • 3-aminopropyltriethoxysilane 3-aminopropyltri (methoxyethoxy) silane, diphenylphosphinoethyldimethylethoxysilane. Since these materials have a relatively small molecular weight of about 200 to 300, the functional groups are likely to perform thermal motion and can improve the diffusion of lithium ions. Further, since the surface treatment agent is composed of short side chains such as methyl group and ethyl group, a large number of functional groups can be imparted to the surface of the electrode conductive agent, and the surface potential can be kept higher. If the surface of the electrode conductive agent is kept at a positive potential, it may be modified with other known functional groups.
  • an electrode electrically conductive agent in combination of multiple types among surface treating agents.
  • a plurality of types of conductive materials may be used in combination as the electrode conductive agent, but at least one of the conductive materials needs to be surface-modified with a surface treatment agent.
  • the type of functional group on the surface of the electrode conductive agent can be confirmed by optical measurement such as XPS.
  • the average from the functional groups on the surface of the electrode conductive agent 0.3nm of Li ion density 1.50 nm -3 or less, even 1.10 nm -3 or less and further is 0.90 nm -3 or less.
  • the number of functional groups on the surface of the electrode conductive agent is preferably 0.01 or more and 5 or less, more preferably 0.6 or more and 2.4 or less per square nanometer.
  • the number of functional groups on the surface of the electrode conductive agent is determined by measuring the coverage from infrared spectroscopy, XPS spectrum analysis, etc., and multiplying it by the specific surface area of the electrode conductive agent.
  • the coating agent may be formed on the entire surface or part of the electrode conductive agent by coating the surface with a metal oxide or the like so that the surface potential of the electrode conductive agent becomes positive.
  • the surface area of the coating agent occupying the electrode conductive agent is preferably 30% or more and 70% or less of the total surface area of the electrode conductive agent so that the electronic conductivity of the electrode conductive agent is not reduced by the coating.
  • the surface area of the electrode conductive agent can be obtained from infrared spectroscopy, XPS spectrum analysis, or the like.
  • the positive electrode current collector 10 is preferably a low-resistance conductor having heat resistance that can withstand the heating during the secondary battery manufacturing process and the operating temperature of the secondary battery, but is not limited thereto.
  • metal foil thinness of 10 ⁇ m or more and 100 ⁇ m or less
  • perforated metal foil thinness of 10 ⁇ m or more and 100 ⁇ m or less, pore diameter of 0.1 mm or more and 10 mm or less
  • species aluminum, stainless steel, titanium, a noble metal (for example, gold, silver, platinum) etc. can be used.
  • ⁇ Positive electrode 70> A positive electrode slurry in which a positive electrode active material 42, a positive electrode conductive agent 43, a positive electrode binder, and an organic solvent are mixed is attached to the positive electrode current collector 10 by a doctor blade method, a dipping method, or a spray method, and then the organic solvent is dried. Then, the positive electrode 70 can be produced by pressure forming with a roll press. In addition, a plurality of positive electrode mixture layers 40 can be laminated on the positive electrode current collector 10 by performing a plurality of times from application to drying.
  • the positive electrode active material and the active material contain a solid electrolyte 55 and function as a conduction path for lithium ions in the positive electrode.
  • ⁇ Negative electrode active material 62 As a material of the negative electrode active material 62, for example, a carbon-based material (for example, graphite, graphitizable carbon material, amorphous carbon material), a conductive polymer material (for example, polyacene, polyparaphenylene, polyaniline, polyacetylene), A lithium composite oxide (eg, lithium titanate: Li 4 Ti 5 O 12 ), metal lithium, or a metal alloyed with lithium (eg, aluminum, silicon, tin) can be used, but is not limited thereto.
  • a carbon-based material for example, graphite, graphitizable carbon material, amorphous carbon material
  • a conductive polymer material for example, polyacene, polyparaphenylene, polyaniline, polyacetylene
  • a lithium composite oxide eg, lithium titanate: Li 4 Ti 5 O 12
  • metal lithium or a metal alloyed with lithium (eg, aluminum, silicon, tin) can be used, but
  • the negative electrode current collector 20 is desirably a low-resistance conductor having heat resistance capable of withstanding the heating during the secondary battery manufacturing process and the operating temperature of the secondary battery.
  • metal foil thickness of 10 ⁇ m or more and 100 ⁇ m or less
  • perforated metal foil thickness of 10 ⁇ m or more and 100 ⁇ m or less, pore diameter of 0.1 mm or more and 10 mm or less
  • expanded metal foamed metal plate, glassy carbon plate and the like.
  • a metal seed species, copper, stainless steel, titanium, nickel, a noble metal (for example, gold, silver, platinum) etc. can be used.
  • ⁇ Negative electrode 80> A negative electrode slurry obtained by mixing a negative electrode active material 62, a negative electrode conductive agent 63, and an organic solvent containing a small amount of water is used as a reverse roll method, direct roll method, blade method, knife method, extrusion method, curtain method, gravure method, bar After making it adhere to the negative electrode current collector 20 and the negative electrode surface of the interconnector 90 by a method, a dip method, a squeeze method, a spray method, etc., the organic solvent is dried, and a negative electrode is produced by pressure forming with a roll press. be able to.
  • a plurality of negative electrode mixture layers 60 can be laminated on the negative electrode current collector 20 and the interconnector 90 by performing a plurality of times from application to drying.
  • the solid electrolyte 55 includes inorganic particles 51 and an ion conductive material 52. By supporting the ion conductive material 52 on the inorganic particles 51, a semi-solid solid electrolyte 55 (semi-solid electrolyte) is formed.
  • Examples of the method for producing the solid electrolyte 55 include the following methods.
  • the ionic conductive material 52 and the inorganic particles 51 are mixed at a specific volume ratio, and an organic solvent such as methanol is added and mixed to prepare a slurry of the solid electrolyte 55. Thereafter, the slurry is spread on a petri dish, and the organic solvent is distilled off to obtain a solid electrolyte 55 powder.
  • the volume fraction of the ionic conductive material 52 is 30 volumes. % To 90% by volume is preferable.
  • the volume fraction of the ionic conductive material 52 is lower than the range, the lithium ion conductivity is lowered.
  • the volume ratio is higher than the range, the ionic conductive material 52 that is not held on the surface of the inorganic particles 51 is increased, resulting in a semi-solid electrolyte. It becomes difficult to maintain the shape.
  • the inorganic particles 51 are preferably insulating particles, insoluble in an organic solvent such as an ionic liquid or glyme, and having no electrical conductivity.
  • oxide nanoparticles such as SiO 2 , Al 2 O 3 , CeO 2 , ZrO 2 , BaTiO 3 , ZnO, TiO 2 are preferable, such as Li 7 La 3 Zr 2 O 12 and Li x La 1-x TiO 3. Those having lithium ion conductivity can also be preferably used.
  • the surface of the nanoparticles may be modified with a known functional group such as a hydroxy group, a carboxyl group, or an amino group, and hexamethyldisilazane, trimethylethoxysilane, trimethylmethoxy may be used as the silane coupling agent.
  • a known hydrophobic treatment may be performed with silane, trimethylsilyl chloride, methyltriethoxysilane, dimethyldiethoxysilane, decyltrimethoxysilane, or the like.
  • other known metal oxide particles may be used.
  • the average particle size of the primary particles of the inorganic particles 51 is preferably 1 nm or more and 10 ⁇ m or less. If the average particle diameter is larger than the above range, the inorganic particles 51 cannot appropriately hold a sufficient amount of the organic solvent, and it may be difficult to form a semi-solid electrolyte. On the other hand, if the average particle diameter is smaller than the above range, the inter-surface force between the inorganic particles 51 is increased, and the particles are likely to aggregate, making it difficult to form a semi-solid electrolyte.
  • the average particle size of the primary particles of the inorganic particles 51 is more preferably 1 nm to 50 nm, and still more preferably 1 nm to 10 nm.
  • the average particle size of the inorganic particles 51 is an average particle size that can be measured using a known particle size distribution measuring apparatus using a laser scattering method.
  • SiO 2 particles average particle size: 7 nm, zeta potential: about ⁇ 20 mV
  • a highly heat-resistant quasi-solid electrolyte can be obtained.
  • ⁇ -Al 2 O 3 particles (average particle size: 5 nm, zeta potential: about ⁇ 5 mV) are used as the inorganic particles 51, it is possible to increase the number of times of charge and discharge of the secondary battery. Although the exact reason is unclear, it is considered that precipitation of lithium dendrite on the negative electrode side during the charge / discharge cycle can be suppressed by using alumina particles having high reduction resistance.
  • the ionic conductive material 52 is an ionic liquid or a mixture of glymes and lithium salts that exhibit similar properties to the ionic liquid.
  • the ionic liquid a known ionic liquid that functions as an electrolyte can be used. From the viewpoint of ionic conductivity (conductivity), N, N-diethyl-N-methyl-N- (2-methoxyethyl) is particularly preferable. Ammonium bis (trifluoromethanesulfonyl) imide (DEME-TFSI) can be preferably used.
  • DEME-TFSI Ammonium bis (trifluoromethanesulfonyl) imide
  • Glymes (R—O (CH 2 CH 2 O) n—R ′ (R and R ′ are saturated hydrocarbons, n is an integer), a generic name for symmetric glycol diethers) are similar to ionic liquids Known glymes exhibiting properties can be used, but from the viewpoint of ion conductivity (conductivity), tetraglyme (tetraethylene dimethyl glycol, G4), triglyme (triethylene glycol dimethyl ether, G3), pentag lime (penta Ethylene glycol dimethyl ether (G5) and hexaglyme (hexaethylene glycol dimethyl ether, G6) can be preferably used.
  • lithium salt LiPF 6, LiBF 4, LiClO 4, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, lithium bis oxalate borate (LiBOB), and lithium imide salt (e.g., lithium Bis (fluorosulfonyl) imide, LiFSI) or the like can be preferably used.
  • lithium imide salt e.g., lithium Bis (fluorosulfonyl) imide, LiFSI
  • LiFSI lithium bis oxalate borate
  • the mixed molar ratio of the lithium salt to the ambient temperature molten salt or the organic solvent is preferably 0.1 or more and 10 or less. If the lithium salt ratio is higher than the range, it is difficult to dissolve the lithium salt. If the lithium salt ratio is lower than the range, the lithium carrier in the electrolyte is reduced, so the secondary battery has a low output, and the cycle of the secondary battery The characteristics are also degraded.
  • the mixing molar ratio is more preferably 0.5 or more and 5 or less, and further preferably 0.8 or more and 3 or less.
  • Electrolyte binder 53 As the electrolyte binder 53, a fluorine-based resin is preferably used. PVDF and PTFE are preferably used as the fluorine-based resin. By using PVDF or PTFE, the adhesion between the solid electrolyte layer 50 and the electrode current collector is improved, so that the battery performance is improved.
  • Solid electrolyte layer 50 There are a method of compression molding the powder of the solid electrolyte 55 into a pellet using a molding die or the like, and a method of adding and mixing the electrolyte binder 53 to the powder of the solid electrolyte 55 to form a sheet.
  • a highly flexible solid electrolyte layer 50 electrolyte sheet
  • the solid electrolyte layer 50 can be produced by adding and mixing a solution of a binder in which the electrolyte binder 53 is dissolved in the dispersion solvent to the solid electrolyte 55 and distilling off the dispersion solvent.
  • LiTFSI lithium bis (trifluorosulfonyl) imide
  • acetylene black average particle size 48 nm
  • PTFE binder
  • acetylene black is vacuum-dried at 120 ° C., and then acetylene black is dispersed in toluene and refluxed at 100 ° C. Further, 3-aminopropyltriethoxysilane is added as a surface treating agent to the mixed solution, and the mixture is refluxed for 6 hours while stirring uniformly. Thereafter, the reaction solution is collected, washed thoroughly with methanol, and the unreacted surface treatment agent is hydrolyzed with a water-methanol solution to obtain surface-modified acetylene black.
  • Example 2 The same as Example 1 except that diethylphosphotoethyltriethoxysilane was used as the surface treatment agent.
  • Example 2 The same as Example 1 except that 3-aminopropyltrimethoxysilane was used as the surface treatment agent.
  • Example 2 The same as Example 1 except that 4-aminobutyltriethoxysilane was used as the surface treatment agent.
  • Example 2 The same as Example 1 except that aminophenyltrimethoxysilane was used as the surface treatment agent.
  • Example 2 The same as Example 1 except that 3-aminopropyltri (methoxyethoxy) silane was used as the surface treatment agent.
  • Example 2 The same as Example 1 except that diphenylphosphinoethyldimethylethoxysilane was used as the surface treatment agent.
  • Example 2 The same as Example 1 except that the number of functional groups (functional group density) on the surface of the electrode conductive agent was 2.4 per square nanometer.
  • Example 1 is the same as Example 1 except that the surface of the electrode conductive agent is modified with a hydroxy group.
  • Comparative example 2 The same as Comparative Example 1, except that the number of functional groups on the surface of the electrode conductive agent was 4.8 per square nanometer.
  • FIG. 4 shows the results of Examples 1 to 8 and Comparative Examples 1 to 2.
  • Example 1 Example 2, Comparative Example 1, and Comparative Example 2
  • Li ions were measured in three regions with distances of 0.3, 0.9, and 1.5 nm from the functional group formed on the surface of the electrode conductive agent. The density is shown. Focusing on Example 1 and Example 2, it can be seen that the Li ion density decreases as the surface of the electrode conductive agent is approached, such as from 1.5 nm to 0.3 nm. In particular, compared to Comparative Example 1 and Comparative Example 2, the Li ion density on the electrode conductive agent surface (0.3 nm) is reduced to about 50%.
  • Examples 1 to 8 and Comparative Examples 1 to 2 are compared, the adsorption amounts of Li ions of Examples 1 to 8 are the same as those of Comparative Examples 1 to 2. More specifically, since the average Li ion density of 0.3 nm from the functional group is 1.50 nm ⁇ 3 or less, Examples 1 to 8 are Li ions. It turns out that it is effective for adsorption

Abstract

The present invention improves the ionic conductance of a secondary battery electrode. Thus, a secondary battery electrode containing an electrode active material, an electrode conductive agent, and an ion conductive material, wherein: the ion conductive material is held by the electrode conductive agent, a coating is formed on the surface of the electrode conductive agent, and the surface potential of the electrode conductive agent is positive; and the materials used to form the coating include, for example, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 4-aminobutyltriethoxysilane, aminophenyltrimethoxysilane, 3-aminophenyltrimethoxysilane, m-aminophenyltrimethoxysilane, p-aminophenyltrimethoxysilane, 3-aminopropyltri(methoxyethoxy)silane, 11-aminoundecyltriethoxysilane, and the like.

Description

二次電池用電極、二次電池、それらの製造方法Secondary battery electrode, secondary battery, and production method thereof
本発明は、二次電池用電極、二次電池、それらの製造方法に関する。 The present invention relates to an electrode for a secondary battery, a secondary battery, and a method for producing them.
高電圧および高エネルギー密度を実現できるリチウムイオン二次電池は、電気自動車やハイブリット自動車などの車載用から、パソコンや携帯型の通信機器に至るまで幅広い用途で用いられている。 Lithium ion secondary batteries capable of realizing high voltage and high energy density are used in a wide range of applications from in-vehicle use such as electric vehicles and hybrid vehicles to personal computers and portable communication devices.
　リチウムイオン二次電池の研究開発における中心課題は、エネルギー密度の更なる向上と、電池自体の安全性、信頼性向上との両立である。この達成に向けて、近年、高リチウムイオン伝導度化を有する固体電解質膜の開発が精力的に進められている。電解質の固体化が要求される背景には、可燃性電解液の漏れ出しや短絡など、有機電解液を電解質として用いた場合に生じる安全上の問題点がある。
固体電解質の代表例としては、リチウムイオン伝導性を有する酸化物や硫化物系セラミックスを用いた固体電解質が上げられる。これは、電解液自体を含まないため高い耐火性を有するが特徴である。加えて、有機電解液同等の高いリチウムイオン伝導度を示す物質群の存在も報告されている。一方で、これらのセラミックス系電解質膜は柔軟性や形成加工性に乏しいという本質的な問題を有する。そのため、電解質粒子と電極活物質粒子との接触が不十分になりやすく、粒子間のリチウムイオン伝導を阻害する要因となる。
電解質の固体化に向けたその他のアプローチとしては、ナノ粒子やマイクロ粒子によって電解液を担持させた半固体電解質膜や半固体電解質電極が考案されている。これらの電極には、安全性向上のために常温溶融塩（イオン液体）が用いられることが多い。 The central issue in the research and development of lithium ion secondary batteries is to further improve the energy density and improve the safety and reliability of the battery itself. To achieve this, in recent years, development of solid electrolyte membranes having high lithium ion conductivity has been vigorously advanced. There is a safety problem that arises when an organic electrolyte is used as an electrolyte, such as leakage of a flammable electrolyte or a short circuit, as a background that requires solidification of the electrolyte.
A typical example of the solid electrolyte is a solid electrolyte using an oxide or sulfide-based ceramic having lithium ion conductivity. This is characterized by high fire resistance because it does not contain the electrolyte itself. In addition, the existence of a substance group exhibiting high lithium ion conductivity equivalent to that of an organic electrolyte has been reported. On the other hand, these ceramic electrolyte membranes have an essential problem that they are poor in flexibility and forming workability. Therefore, the contact between the electrolyte particles and the electrode active material particles tends to be insufficient, which becomes a factor that inhibits lithium ion conduction between the particles.
As another approach for solidifying an electrolyte, a semi-solid electrolyte membrane or a semi-solid electrolyte electrode in which an electrolyte is supported by nanoparticles or micro particles has been devised. For these electrodes, a room temperature molten salt (ionic liquid) is often used to improve safety.
　前記のようなイオン液体を含む電極において、その導電性を向上させるために電極にイオン液体を含有させる方法が検討されている。特許文献１には、平均粒径がＤａである電極材粒子と平均粒径がＤｂである固体粒子とイオン液体とを液体媒体に分散させて分散液を得る工程、分散液を支持体上に塗布して分散液膜を形成する工程、分散液膜から液体媒体を除去して支持体上に電極膜を形成する工程、支持体を除去して電極膜を単離する工程を含むことを特徴とする方法が開示されている。 In the electrode containing the ionic liquid as described above, a method for containing the ionic liquid in the electrode has been studied in order to improve the conductivity. In Patent Document 1, electrode material particles having an average particle diameter of Da, solid particles having an average particle diameter of Db, and an ionic liquid are dispersed in a liquid medium to obtain a dispersion, and the dispersion is placed on a support. A step of forming a dispersion film by coating, a step of forming an electrode film on the support by removing the liquid medium from the dispersion film, and a step of isolating the electrode film by removing the support. A method is disclosed.
特開２００９－２３１８２９号公報JP 2009-231829 A
　特許文献１では、電極材粒子の中にアセチレンブラックが用いられているが、アセチレンブラック等の導電材の表面電位はマイナスであるため、導電材にイオン液体中のリチウムイオンが吸着し、二次電池用電極のイオン伝導度が低下する可能性がある。 In Patent Document 1, acetylene black is used in the electrode material particles. However, since the surface potential of the conductive material such as acetylene black is negative, lithium ions in the ionic liquid are adsorbed on the conductive material, and the secondary material is secondary. The ionic conductivity of the battery electrode may be reduced.
　本発明は、二次電池用電極のイオン伝導度を向上させることを目的とする。 An object of the present invention is to improve the ionic conductivity of an electrode for a secondary battery.
　上記課題を解決するための本発明の特徴は、例えば以下の通りである。 The features of the present invention for solving the above problems are as follows, for example.
　電極活物質、電極導電剤、イオン導電材を含み、イオン導電材は電極導電剤に保持され、電極導電剤の表面に被覆剤が形成され、電極導電剤の表面電位は正である二次電池用電極。 A secondary battery that includes an electrode active material, an electrode conductive agent, and an ionic conductive material, the ionic conductive material is held by the electrode conductive agent, a coating is formed on the surface of the electrode conductive agent, and the surface potential of the electrode conductive agent is positive Electrode.
　本発明により、二次電池用電極のイオン伝導度を向上できる。上記した以外の課題、構成及び効果は以下の実施形態の説明により明らかにされる。 According to the present invention, the ionic conductivity of the secondary battery electrode can be improved. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.
本発明の一実施形態に係る二次電池の断面図である。It is sectional drawing of the secondary battery which concerns on one Embodiment of this invention. 本発明の一実施形態に係る二次電池の断面図である。It is sectional drawing of the secondary battery which concerns on one Embodiment of this invention. 本発明の一実施形態に係る二次電池の要部の断面図である。It is sectional drawing of the principal part of the secondary battery which concerns on one Embodiment of this invention. 本発明の一実施形態に係る実施例および比較例の結果である。It is a result of the Example and comparative example which concern on one Embodiment of this invention.
　以下、図面等を用いて、本発明の実施形態について説明する。以下の説明は本発明の内容の具体例を示すものであり、本発明がこれらの説明に限定されるものではなく、本明細書に開示される技術的思想の範囲内において当業者による様々な変更および修正が可能である。また、本発明を説明するための全図において、同一の機能を有するものは、同一の符号を付け、その繰り返しの説明は省略する場合がある。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description shows specific examples of the contents of the present invention, and the present invention is not limited to these descriptions. Various modifications by those skilled in the art are within the scope of the technical idea disclosed in this specification. Changes and modifications are possible. In all the drawings for explaining the present invention, components having the same function are denoted by the same reference numerals, and repeated description thereof may be omitted.
　本明細書では、全固体電池としてリチウムイオン二次電池を例にして説明するが、本発明の技術的思想は、リチウムイオン二次電池の他、ナトリウムイオン二次電池、マグネシウムイオン二次電池、アルミニウムイオン二次電池などに対しても適用することができる。 In this specification, a lithium ion secondary battery will be described as an example of an all-solid battery, but the technical idea of the present invention is not only a lithium ion secondary battery, but also a sodium ion secondary battery, a magnesium ion secondary battery, The present invention can also be applied to an aluminum ion secondary battery.
　図１は、本発明の一実施形態に係る二次電池の断面図である。図１に示すように、全固体電池１００は、正極７０、負極８０、電池ケース３０及び固体電解質層５０を有する。電池ケース３０は、固体電解質層５０、正極７０、負極８０、を収容する。電池ケース３０の材料としては、アルミニウム、ステンレス鋼、ニッケルメッキ鋼等、非水電解質に対し耐食性のある材料から選択することができる。 FIG. 1 is a cross-sectional view of a secondary battery according to an embodiment of the present invention. As shown in FIG. 1, the all-solid battery 100 includes a positive electrode 70, a negative electrode 80, a battery case 30, and a solid electrolyte layer 50. The battery case 30 accommodates the solid electrolyte layer 50, the positive electrode 70, and the negative electrode 80. The material of the battery case 30 can be selected from materials that are corrosion resistant to non-aqueous electrolytes, such as aluminum, stainless steel, and nickel-plated steel.
　全固体電池１００内で正極７０、固体電解質層５０、負極８０で構成される電極体が積層されている。正極７０は、正極集電体１０及び正極合剤層４０を有する。正極集電体１０の両面に正極合剤層４０が形成されている。負極８０は、負極集電体２０及び負極合剤層６０を有する。負極集電体２０の両面に負極合剤層６０が形成されている。正極集電体１０および負極集電体２０は電池ケース３０の外部に突出しており、突出した複数の正極集電体１０同士、複数の負極集電体２０同士が、例えば超音波接合などで接合されることで、全固体電池１００内で並列接続が形成される。 In the all-solid-state battery 100, an electrode body composed of the positive electrode 70, the solid electrolyte layer 50, and the negative electrode 80 is laminated. The positive electrode 70 includes the positive electrode current collector 10 and the positive electrode mixture layer 40. A positive electrode mixture layer 40 is formed on both surfaces of the positive electrode current collector 10. The negative electrode 80 includes a negative electrode current collector 20 and a negative electrode mixture layer 60. Negative electrode mixture layers 60 are formed on both surfaces of the negative electrode current collector 20. The positive electrode current collector 10 and the negative electrode current collector 20 protrude outside the battery case 30, and the plurality of protruding positive electrode current collectors 10 and the plurality of negative electrode current collectors 20 are bonded together by, for example, ultrasonic bonding. As a result, a parallel connection is formed in the all solid state battery 100.
　正極合剤層４０、固体電解質層５０、負極合剤層６０、インターコネクタ、が積層されて全固体電池１００内で直列接続が構成されたバイポーラ型の二次電池としてもよい。図２は、本発明の一実施形態に係る二次電池の断面図である。 A bipolar secondary battery in which the positive electrode mixture layer 40, the solid electrolyte layer 50, the negative electrode mixture layer 60, and the interconnector are stacked to form a series connection in the all solid battery 100 may be used. FIG. 2 is a cross-sectional view of a secondary battery according to an embodiment of the present invention.
　図２の全固体電池１００は、正極合剤層４０、負極合剤層６０、及び固体電解質層５０を複数層含む。図中のバイポーラ型全固体電池２００のうち最外の正極合剤層４０および負極合剤層６０は、正極集電体１０および負極集電体２０と接続される。また、電池ケース３０内で隣り合う正極合剤層４０および負極合剤層６０の間には集電体としてのインターコネクタ９０が配置される。インターコネクタ９０には、電子伝導性が高いこと、イオン伝導性がないこと、負極合剤層６０と正極合剤層４０に接触する面がそれぞれの電位によって酸化還元反応を示さないこと、などが挙げられる。インターコネクタ９０に用いることにできる材料としては、以下の正極集電体１０および負極集電体２０に用いることのできる材料を含む。具体的には、アルミニウム箔やＳＵＳ箔を挙げることができる。または、正極集電体１０と負極集電体２０とをクラッド成型および電子伝導性スラリーで貼り合わせることもできる。 2 includes a plurality of positive electrode mixture layers 40, negative electrode mixture layers 60, and solid electrolyte layers 50. Outermost positive electrode mixture layer 40 and negative electrode mixture layer 60 in bipolar all solid state battery 200 in the figure are connected to positive electrode current collector 10 and negative electrode current collector 20. Further, an interconnector 90 as a current collector is disposed between the positive electrode mixture layer 40 and the negative electrode mixture layer 60 that are adjacent to each other in the battery case 30. The interconnector 90 has high electronic conductivity, no ionic conductivity, and the surface in contact with the negative electrode mixture layer 60 and the positive electrode mixture layer 40 does not exhibit a redox reaction depending on the respective potentials. Can be mentioned. Materials that can be used for the interconnector 90 include materials that can be used for the following positive electrode current collector 10 and negative electrode current collector 20. Specific examples include aluminum foil and SUS foil. Alternatively, the positive electrode current collector 10 and the negative electrode current collector 20 can be bonded together by clad molding and electron conductive slurry.
　図３は、本発明の一実施形態に係る二次電池の要部の断面図である。正極合剤層４０は、正極活物質４２、正極導電剤４３、それらを結着するための正極バインダ、任意の無機粒子５１、およびイオン導電材５２を有している。負極合剤層６０は、負極活物質６２、負極導電剤６３、それらを結着するための負極バインダ、任意の無機粒子５１、およびイオン導電材５２を有している。固体電解質層５０は、電解質バインダ５３および固体電解質５５を有する。固体電解質５５は、無機粒子５１およびイオン導電材５２を有する。 FIG. 3 is a cross-sectional view of a main part of the secondary battery according to the embodiment of the present invention. The positive electrode mixture layer 40 includes a positive electrode active material 42, a positive electrode conductive agent 43, a positive electrode binder for binding them, arbitrary inorganic particles 51, and an ionic conductive material 52. The negative electrode mixture layer 60 includes a negative electrode active material 62, a negative electrode conductive agent 63, a negative electrode binder for binding them, arbitrary inorganic particles 51, and an ionic conductive material 52. The solid electrolyte layer 50 has an electrolyte binder 53 and a solid electrolyte 55. The solid electrolyte 55 includes inorganic particles 51 and an ion conductive material 52.
　正極７０、負極８０を電極（二次電池用電極）、正極導電剤４３または負極導電剤６３を電極導電材、正極バインダまたは負極バインダを電極バインダ、正極活物質４２または負極活物質６２を電極活物質、と称する場合がある。 The positive electrode 70 and the negative electrode 80 are electrodes (secondary battery electrodes), the positive electrode conductive agent 43 or the negative electrode conductive agent 63 is an electrode conductive material, the positive electrode binder or the negative electrode binder is an electrode binder, and the positive electrode active material 42 or the negative electrode active material 62 is an electrode active material. Sometimes referred to as a substance.
　＜電極バインダ＞
　電極バインダとしては、スチレン－ブタジエンゴム、カルボキシメチルセルロ－ス、ポリフッ化ビニリデン（ＰＶＤＦ）、ポリテトラフルオロエチレン（ＰＴＦＥ）、ポリ（ビニリデンフルオリド－ｃｏ－ヘキサフルオロプロピレン）共重合体（ＰＶｄＦ－ＨＦＰ）及びこれらの混合物等が挙げられるが、これに限られない。 <Electrode binder>
As the electrode binder, styrene-butadiene rubber, carboxymethyl cellulose, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), poly (vinylidene fluoride-co-hexafluoropropylene) copolymer (PVdF-HFP) ) And mixtures thereof, but are not limited thereto.
　＜正極活物質４２＞
　正極活物質４２の材料として、例えば、遷移金属を含むリチウム複合酸化物が好ましく、具体例としては、ＬｉＣｏＯ２、ＬｉＮｉＯ２、ＬｉＭｎ２Ｏ４、ＬｉＭｎＯ３、ＬｉＭｎ２Ｏ３、ＬｉＭｎＯ２、Ｌｉ４Ｍｎ５Ｏ１２、Ｌｉ２Ｍｎ３ＭＯ８（Ｍ＝Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｚｎ）、Ｌｉ１－ｘＭｘＭｎ２Ｏ４（Ｍ＝Ｍｇ、Ｂ、Ａｌ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｒ、Ｚｎ、Ｃａ、ｘ＝０．０１～０．１）、ＬｉＭｎ２－ｘＭｘＯ２（Ｍ＝Ｃｏ、Ｎｉ、Ｆｅ、Ｃｒ、Ｚｎ、Ｔａ、ｘ＝０．０１～０．２）、ＬｉＣｏ１－ｘＭｘＯ２（Ｍ＝Ｎｉ、Ｆｅ、Ｍｎ、ｘ＝０．０１～０．２）、ＬｉＮｉ１－ｘＭｘＯ２（Ｍ＝Ｍｎ、Ｆｅ、Ｃｏ、Ａｌ、Ｇａ、Ｃａ、Ｍｇ、ｘ＝０．０１～０．２）、ＬｉＮｉ１－ｘ－ｙＭｎｘＣｏｙＯ２（ｘ＝０．１～０．８、ｙ＝０．１～０．８、ｘ＋ｙ＝０．１～０．９）、ＬｉＦｅＯ２、ＬｉＦｅＰＯ４、ＬｉＭｎＰＯ４などが挙げられるが、これに限られない。 <Positive electrode active material 42>
As the material of the positive electrode active material 42, for example, a lithium composite oxide containing a transition metal is preferable, and specific examples include LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , LiMnO 3 , LiMn 2 O 3 , LiMnO 2 , Li 4. Mn 5 O 12 , Li 2 Mn 3 MO 8 (M = Fe, Co, Ni, Cu, Zn), Li 1-x M x Mn 2 O 4 (M = Mg, B, Al, Fe, Co, Ni, Cr, Zn, Ca, x = 0.01 to 0.1), LiMn 2−x M x O 2 (M = Co, Ni, Fe, Cr, Zn, Ta, x = 0.01 to 0.2) LiCo 1-x M x O 2 (M = Ni, Fe, Mn, x = 0.01 to 0.2), LiNi 1-x M x O 2 (M = Mn, Fe, Co, Al, Ga, Ca, Mg, x = 0.01 to 0.2), LiNi 1− x-y Mn x Co y O 2 (x = 0.1 ~ 0.8, y = 0.1 ~ 0.8, x + y = 0.1 ~ 0.9), LiFeO 2, LiFePO 4, LiMnPO 4 , etc. However, it is not limited to this.
　＜電極導電剤＞
　電極導電剤としては、導電性繊維（例えば、気相成長炭素、カーボンナノチューブ、ピッチ（石油、石炭、コールタールなどの副生成物）を原料に高温で炭化して製造した繊維、アクリル繊維から製造した炭素繊維など）が好適に用いられる。また、電極導電剤は、電極活物質よりも電気抵抗率の低い材料であって、電極の充放電電位（正極７０の場合は、通常、２．５～４．５Ｖ）にて酸化溶解しない材料を使用してもよい。例えば、耐食性金属（チタンや金など）、炭化物（ＳｉＣやＷＣなど）、窒化物（Ｓｉ３Ｎ４やＢＮなど）が挙げられる。高比表面積の炭素材料（例えば、カーボンブラックや活性炭など）も使用できるが、これに限られない。 <Electrode conductive agent>
As the electrode conductive agent, manufactured from conductive fibers (for example, vapor-grown carbon, carbon nanotubes, pitch (byproducts such as petroleum, coal, coal tar, etc.) and carbonized at high temperature, and acrylic fibers. Carbon fiber etc.) are preferably used. The electrode conductive agent is a material having a lower electrical resistivity than the electrode active material, and does not oxidize and dissolve at the charge / discharge potential of the electrode (usually 2.5 to 4.5 V in the case of the positive electrode 70). May be used. For example, corrosion resistant metals (such as titanium and gold), carbides (such as SiC and WC), and nitrides (such as Si3N4 and BN) can be used. A carbon material having a high specific surface area (for example, carbon black or activated carbon) can be used, but is not limited thereto.
　本発明では、電極内にイオン導電材５２が含まれている。この時、無機粒子５１と同様に、イオン導電材５２が電極導電剤に担持されることにより、半固体状の半固体電解質が構成される。 In the present invention, an ionic conductive material 52 is included in the electrode. At this time, similarly to the inorganic particles 51, the ionic conductive material 52 is supported on the electrode conductive agent, whereby a semi-solid semi-solid electrolyte is formed.
　電極導電剤の表面を正電位に保つ処理が施されている。カーボンなどの電極導電剤の表面は負電位であるため、正電荷を有するリチウムイオンは電極導電剤の表面に吸着されてしまう。吸着されたリチウムイオンは電荷輸送に寄与できなくなるため、結果的に電極内部のイオン伝導度が低下する。一方、電極導電剤の表面が正電位であれば、電極導電剤の表面へのリチウムイオン吸着は抑制されるため、電極の内部のイオン伝導の低下を抑制できる。 The treatment of keeping the surface of the electrode conductive agent at a positive potential is performed. Since the surface of the electrode conductive agent such as carbon has a negative potential, lithium ions having a positive charge are adsorbed on the surface of the electrode conductive agent. Since the adsorbed lithium ions can no longer contribute to charge transport, the ionic conductivity inside the electrode decreases as a result. On the other hand, if the surface of the electrode conductive agent is a positive potential, lithium ion adsorption to the surface of the electrode conductive agent is suppressed, so that a decrease in ion conduction inside the electrode can be suppressed.
　電極導電剤の表面を正電位に保つ方法として、表面処理剤を導入する等が挙げられる。これにより、電極導電剤の表面全体または部分的に被覆剤が形成される。表面処理剤として、例えば、３－アミノプロピルトリエトキシシランや、３－アミノプロピルトリメトキシシラン、４－アミノブチルトリエトキシシラン、アミノフェニルトリメトキシシラン、３－アミノフェニルトリメトキシシラン、ｍ－アミノフェニルトリメトキシシラン、ｐ－アミノフェニルトリメトキシシラン、３－アミノプロピルトリ（メトキシエトキシ）シラン、１１－アミノウンデシルトリエトキシシラン、２－（４－プロピルエチル）トリエトキシシラン、ジエチルホスフォトエチルトリエトキシシラン、ジフェニルホスフィノエチルジメチルエトキシシラン、ジフェニルフォスフィノエチルジメチルエトキシシラン、２－（ジフェニルフォスフィノ）エチルトリエトキシシラン、ビス（２－ジフェニルフォスフィノエチル）メチルシリエチルトリエトキシシラン等が挙げられる。このような表面処理剤を用いることで、電極導電剤の表面にアミノ基やホスフィン基のいずれか一種以上が導入される。 As a method for keeping the surface of the electrode conductive agent at a positive potential, a surface treatment agent is introduced. As a result, the coating agent is formed on the entire surface or part of the electrode conductive agent. Examples of surface treatment agents include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 4-aminobutyltriethoxysilane, aminophenyltrimethoxysilane, 3-aminophenyltrimethoxysilane, and m-aminophenyl. Trimethoxysilane, p-aminophenyltrimethoxysilane, 3-aminopropyltri (methoxyethoxy) silane, 11-aminoundecyltriethoxysilane, 2- (4-propylethyl) triethoxysilane, diethylphosphotoethyltriethoxy Silane, diphenylphosphinoethyldimethylethoxysilane, diphenylphosphinoethyldimethylethoxysilane, 2- (diphenylphosphino) ethyltriethoxysilane, bis (2-diphenylphosphinoethyl) Methyl silicate ethyl triethoxysilane, and the like. By using such a surface treatment agent, at least one of an amino group and a phosphine group is introduced onto the surface of the electrode conductive agent.
　上記の表面処理剤の中で、３－アミノプロピルトリエトキシシラン、３－アミノプロピルトリ（メトキシエトキシ）シラン、ジフェニルホスフィノエチルジメチルエトキシシランを用いることが望ましい。これらの材料は分子量が２００～３００程度と比較的小さいために官能基が熱運動をしやすく、リチウムイオンの拡散を向上できる。また、表面処理剤は短い側鎖、例えばメチル基やエチル基などから構成されているため、電極導電剤の表面に多数の官能基を付与でき、表面電位をより高く保てる。電極導電剤の表面が正電位に保たれるならば、この他の公知の官能基で修飾してもよい。このとき、表面処理剤のうち、複数種を組み合わせて電極導電剤の表面を修飾してもよい。また、電極導電剤として複数種の導電材を組み合わせて用いてもよいが、導電材の内の少なくとも一種類は表面処理剤によって表面修飾されている必要がある。電極導電剤の表面の官能基の種類については、ＸＰＳなどの光学測定で確認できる。 Among the above surface treating agents, it is desirable to use 3-aminopropyltriethoxysilane, 3-aminopropyltri (methoxyethoxy) silane, diphenylphosphinoethyldimethylethoxysilane. Since these materials have a relatively small molecular weight of about 200 to 300, the functional groups are likely to perform thermal motion and can improve the diffusion of lithium ions. Further, since the surface treatment agent is composed of short side chains such as methyl group and ethyl group, a large number of functional groups can be imparted to the surface of the electrode conductive agent, and the surface potential can be kept higher. If the surface of the electrode conductive agent is kept at a positive potential, it may be modified with other known functional groups. At this time, you may modify the surface of an electrode electrically conductive agent in combination of multiple types among surface treating agents. Further, a plurality of types of conductive materials may be used in combination as the electrode conductive agent, but at least one of the conductive materials needs to be surface-modified with a surface treatment agent. The type of functional group on the surface of the electrode conductive agent can be confirmed by optical measurement such as XPS.
　電極導電剤の表面における官能基から０．３ｎｍの平均Ｌｉイオン密度は１．５０ｎｍ－３以下、更には１．１０ｎｍ－３以下、更には０．９０ｎｍ－３以下であることが望ましい。 The average from the functional groups on the surface of the electrode conductive agent 0.3nm of Li ion density 1.50 nm -3 or less, even 1.10 nm -3 or less and further is 0.90 nm -3 or less.
　電極導電剤の表面における官能基数は、１平方ナノメートル当たり０．０１個以上５個以下が好ましく、０．６個以上２．４個以下が特に好ましい。電極導電剤の表面における官能基数は、赤外線分光やＸＰＳスペクトル解析などから被覆率を測定し、電極導電剤の比表面積と掛け合わせることで、求められる。 The number of functional groups on the surface of the electrode conductive agent is preferably 0.01 or more and 5 or less, more preferably 0.6 or more and 2.4 or less per square nanometer. The number of functional groups on the surface of the electrode conductive agent is determined by measuring the coverage from infrared spectroscopy, XPS spectrum analysis, etc., and multiplying it by the specific surface area of the electrode conductive agent.
　また、電極導電剤の表面電位が正になるように、その表面を金属酸化物などによって被覆することにより、電極導電剤の表面全体または部分的に被覆剤が形成されていてもよい。ただし、被覆によって電極導電剤の電子伝導性が低下しないように、電極導電剤を占める被覆剤の表面積は、電極導電剤の全表面積の３０％以上７０％以下とすることが好ましい。電極導電剤の表面積は、赤外線分光やＸＰＳスペクトル解析などから求めることができる。 Further, the coating agent may be formed on the entire surface or part of the electrode conductive agent by coating the surface with a metal oxide or the like so that the surface potential of the electrode conductive agent becomes positive. However, the surface area of the coating agent occupying the electrode conductive agent is preferably 30% or more and 70% or less of the total surface area of the electrode conductive agent so that the electronic conductivity of the electrode conductive agent is not reduced by the coating. The surface area of the electrode conductive agent can be obtained from infrared spectroscopy, XPS spectrum analysis, or the like.
　＜正極集電体１０＞
　正極集電体１０として、二次電池製造プロセス中の加熱や二次電池の運転温度に耐えられる耐熱性を有する低抵抗導電体であることが望ましいが、これに限られない。例えば、金属箔（厚さ１０μｍ以上１００μｍ以下）、穿孔金属箔（厚さ１０μｍ以上１００μｍ以下、孔径０．１ｍｍ以上１０ｍｍ以下）、エキスパンドメタル、発泡金属板、ガラス状炭素板などが挙げられる。また、金属種としては、アルミニウム、ステンレス鋼、チタン、貴金属（例えば、金、銀、白金）などを用いることができる。 <Positive electrode current collector 10>
The positive electrode current collector 10 is preferably a low-resistance conductor having heat resistance that can withstand the heating during the secondary battery manufacturing process and the operating temperature of the secondary battery, but is not limited thereto. For example, metal foil (thickness of 10 μm or more and 100 μm or less), perforated metal foil (thickness of 10 μm or more and 100 μm or less, pore diameter of 0.1 mm or more and 10 mm or less), expanded metal, foamed metal plate, glassy carbon plate and the like can be mentioned. Moreover, as a metal seed | species, aluminum, stainless steel, titanium, a noble metal (for example, gold, silver, platinum) etc. can be used.
　＜正極７０＞
　正極活物質４２、正極導電剤４３、正極バインダ、及び有機溶媒を混合した正極スラリーを、ドクターブレード法、ディッピング法、又はスプレー法等によって正極集電体１０へ付着させた後、有機溶媒を乾燥させ、ロールプレスによって加圧成形することにより、正極７０を作製することができる。また、塗布から乾燥までを複数回行うことにより、複数の正極合剤層４０を正極集電体１０に積層化させることも可能である。正極活物質と活物質内には固体電解質５５が含まれ、正極内のリチウムイオンの伝導経路として機能する。 <Positive electrode 70>
A positive electrode slurry in which a positive electrode active material 42, a positive electrode conductive agent 43, a positive electrode binder, and an organic solvent are mixed is attached to the positive electrode current collector 10 by a doctor blade method, a dipping method, or a spray method, and then the organic solvent is dried. Then, the positive electrode 70 can be produced by pressure forming with a roll press. In addition, a plurality of positive electrode mixture layers 40 can be laminated on the positive electrode current collector 10 by performing a plurality of times from application to drying. The positive electrode active material and the active material contain a solid electrolyte 55 and function as a conduction path for lithium ions in the positive electrode.
　＜負極活物質６２＞
　負極活物質６２の材料として、例えば、炭素系材料（例えば、黒鉛、易黒鉛化炭素材料、非晶質炭素材料）、導電性高分子材料（例えば、ポリアセン、ポリパラフェニレン、ポリアニリン、ポリアセチレン）、リチウム複合酸化物（例えば、チタン酸リチウム：Ｌｉ４Ｔｉ５Ｏ１２）、金属リチウム、リチウムと合金化する金属（例えば、アルミニウム、シリコン、スズ）を用いることができるが、これに限られない。 <Negative electrode active material 62>
As a material of the negative electrode active material 62, for example, a carbon-based material (for example, graphite, graphitizable carbon material, amorphous carbon material), a conductive polymer material (for example, polyacene, polyparaphenylene, polyaniline, polyacetylene), A lithium composite oxide (eg, lithium titanate: Li 4 Ti 5 O 12 ), metal lithium, or a metal alloyed with lithium (eg, aluminum, silicon, tin) can be used, but is not limited thereto.
　＜負極集電体２０＞
　負極集電体２０も、正極集電体１０と同様に、二次電池製造プロセス中の加熱や二次電池の運転温度に耐えられる耐熱性を有する低抵抗導電体であることが望ましいが、これに限られない。例えば、金属箔（厚さ１０μｍ以上１００μｍ以下）、穿孔金属箔（厚さ１０μｍ以上１００μｍ以下、孔径０．１ｍｍ以上１０ｍｍ以下）、エキスパンドメタル、発泡金属板、ガラス状炭素板などが挙げられる。また、金属種としては、銅、ステンレス鋼、チタン、ニッケル、貴金属（例えば、金、銀、白金）などを用いることができる。 <Negative electrode current collector 20>
Similarly to the positive electrode current collector 10, the negative electrode current collector 20 is desirably a low-resistance conductor having heat resistance capable of withstanding the heating during the secondary battery manufacturing process and the operating temperature of the secondary battery. Not limited to. For example, metal foil (thickness of 10 μm or more and 100 μm or less), perforated metal foil (thickness of 10 μm or more and 100 μm or less, pore diameter of 0.1 mm or more and 10 mm or less), expanded metal, foamed metal plate, glassy carbon plate and the like can be mentioned. Moreover, as a metal seed | species, copper, stainless steel, titanium, nickel, a noble metal (for example, gold, silver, platinum) etc. can be used.
　＜負極８０＞
　負極活物質６２、負極導電剤６３、及び水を微量含んだ有機溶媒を混合した負極スラリーを、リバースロール法、ダイレクトロール法、ブレード法、ナイフ法、エクストルージョン法、カーテン法、グラビア法、バー法、ディップ法、スクイーズ法およびスプレー法等によって負極集電体２０およびインターコネクタ９０の負極面へ付着させた後、有機溶媒を乾燥させ、ロールプレスによって加圧成形することにより、負極を作製することができる。また、塗布から乾燥までを複数回行うことにより、複数の負極合剤層６０を負極集電体２０およびインターコネクタ９０に積層化させることも可能である。 <Negative electrode 80>
A negative electrode slurry obtained by mixing a negative electrode active material 62, a negative electrode conductive agent 63, and an organic solvent containing a small amount of water is used as a reverse roll method, direct roll method, blade method, knife method, extrusion method, curtain method, gravure method, bar After making it adhere to the negative electrode current collector 20 and the negative electrode surface of the interconnector 90 by a method, a dip method, a squeeze method, a spray method, etc., the organic solvent is dried, and a negative electrode is produced by pressure forming with a roll press. be able to. In addition, a plurality of negative electrode mixture layers 60 can be laminated on the negative electrode current collector 20 and the interconnector 90 by performing a plurality of times from application to drying.
　＜固体電解質５５＞
　固体電解質５５は、無機粒子５１およびイオン導電材５２を有する。イオン導電材５２が無機粒子５１に担持されることにより、半固体状の固体電解質５５（半固体電解質）が構成される。 <Solid electrolyte 55>
The solid electrolyte 55 includes inorganic particles 51 and an ion conductive material 52. By supporting the ion conductive material 52 on the inorganic particles 51, a semi-solid solid electrolyte 55 (semi-solid electrolyte) is formed.
　固体電解質５５の作製方法としては例えば以下の方法が挙げられる。イオン導電材５２と無機粒子５１とを特定の体積比率で混合し、メタノール等の有機溶媒を添加し・混合して、固体電解質５５のスラリーを調合する。その後、該スラリーをシャーレに広げ、有機溶媒を留去して固体電解質５５の粉末が得られる。 Examples of the method for producing the solid electrolyte 55 include the following methods. The ionic conductive material 52 and the inorganic particles 51 are mixed at a specific volume ratio, and an organic solvent such as methanol is added and mixed to prepare a slurry of the solid electrolyte 55. Thereafter, the slurry is spread on a petri dish, and the organic solvent is distilled off to obtain a solid electrolyte 55 powder.
　イオン導電材５２と無機粒子５１の混合比率（体積分率）としては、イオン導電材５２と無機粒子５１との合計体積を１００ｖｏｌ％とした場合に、イオン導電材５２の体積分率は３０体積％以上９０体積％以下が好ましい。該範囲よりもイオン導電材５２の体積分率が低いとリチウムイオン電導度が低下し、該範囲よりも体積比が高いと無機粒子５１表面に保持されないイオン導電材５２が増加して半固体電解質の形状維持が困難になる。 As a mixing ratio (volume fraction) of the ionic conductive material 52 and the inorganic particles 51, when the total volume of the ionic conductive material 52 and the inorganic particles 51 is 100 vol%, the volume fraction of the ionic conductive material 52 is 30 volumes. % To 90% by volume is preferable. When the volume fraction of the ionic conductive material 52 is lower than the range, the lithium ion conductivity is lowered. When the volume ratio is higher than the range, the ionic conductive material 52 that is not held on the surface of the inorganic particles 51 is increased, resulting in a semi-solid electrolyte. It becomes difficult to maintain the shape.
　＜無機粒子５１＞
　無機粒子５１としては、電気化学的安定性の観点から、絶縁性粒子でありイオン液体やグライム類等の有機溶媒に不溶であり、電気伝導性を有していない粒子であることが好ましい。例えば、ＳｉＯ２、Ａｌ２Ｏ３、ＣｅＯ２、ＺｒＯ２、ＢａＴｉＯ３、ＺｎＯ、ＴｉＯ２等の酸化物ナノ粒子が好ましく、Ｌｉ７Ｌａ３Ｚｒ２Ｏ１２やＬｉｘＬａ１－ｘＴｉＯ３などのリチウムイオン伝導性を有するものも好ましく用いることができる。加えて、ナノ粒子表面に対しては、ヒドロキシ基や、カルボキシル基、アミノ基など、公知の官能基修飾を施したり、シランカップリング剤といては、ヘキサメチルジシラザン、トリメチルエトキシシラン、トリメチルメトキシシラン、トリメチルシリルクロライド、メチルトリエトキシシラン、ジメチルジエトキシシラン、デシルトリメトキシシランなどによって公知の疎水処理を施したりしてもよい。また、他の公知の金属酸化物粒子を用いてもよい。 <Inorganic particles 51>
From the viewpoint of electrochemical stability, the inorganic particles 51 are preferably insulating particles, insoluble in an organic solvent such as an ionic liquid or glyme, and having no electrical conductivity. For example, oxide nanoparticles such as SiO 2 , Al 2 O 3 , CeO 2 , ZrO 2 , BaTiO 3 , ZnO, TiO 2 are preferable, such as Li 7 La 3 Zr 2 O 12 and Li x La 1-x TiO 3. Those having lithium ion conductivity can also be preferably used. In addition, the surface of the nanoparticles may be modified with a known functional group such as a hydroxy group, a carboxyl group, or an amino group, and hexamethyldisilazane, trimethylethoxysilane, trimethylmethoxy may be used as the silane coupling agent. A known hydrophobic treatment may be performed with silane, trimethylsilyl chloride, methyltriethoxysilane, dimethyldiethoxysilane, decyltrimethoxysilane, or the like. Further, other known metal oxide particles may be used.
　イオン導電材５２の保持量は無機粒子５１の比表面積に比例すると考えられるため、無機粒子５１の一次粒子の平均粒径は、１ｎｍ以上１０μｍ以下が好ましい。該範囲よりも平均粒径が大きいと、無機粒子５１が十分な量の有機溶媒を適切に保持できず半固体電解質の形成が困難になる可能性がある。また、該範囲よりも平均粒径が小さいと、無機粒子５１間の表面間力が大きくなって粒子同士が凝集し易くなって、半固体電解質の形成が困難になる可能性がある。無機粒子５１の一次粒子の平均粒径は、１ｎｍ以上５０ｎｍ以下がより好ましく、１ｎｍ以上１０ｎｍ以下が更に好ましい。なお、無機粒子５１の平均粒径とは、レーザー散乱法を利用した公知の粒径分布測定装置を用いて測定することができる平均粒径である。 Since the holding amount of the ion conductive material 52 is considered to be proportional to the specific surface area of the inorganic particles 51, the average particle size of the primary particles of the inorganic particles 51 is preferably 1 nm or more and 10 μm or less. If the average particle diameter is larger than the above range, the inorganic particles 51 cannot appropriately hold a sufficient amount of the organic solvent, and it may be difficult to form a semi-solid electrolyte. On the other hand, if the average particle diameter is smaller than the above range, the inter-surface force between the inorganic particles 51 is increased, and the particles are likely to aggregate, making it difficult to form a semi-solid electrolyte. The average particle size of the primary particles of the inorganic particles 51 is more preferably 1 nm to 50 nm, and still more preferably 1 nm to 10 nm. The average particle size of the inorganic particles 51 is an average particle size that can be measured using a known particle size distribution measuring apparatus using a laser scattering method.
　無機粒子５１としてＳｉＯ２粒子（平均粒径：７ｎｍ、ゼータ電位：約－２０ｍＶ）を用いると、高耐熱性の擬似固体電解質が得られる。 When SiO 2 particles (average particle size: 7 nm, zeta potential: about −20 mV) are used as the inorganic particles 51, a highly heat-resistant quasi-solid electrolyte can be obtained.
　無機粒子５１としてγ－Ａｌ２Ｏ３粒子（平均粒径：５ｎｍ、ゼータ電位：約－５ｍＶ）を用いると、二次電池の充放電回数を延ばすことが可能となる。正確な理由は未解明であるが、耐還元性の高いアルミナ粒子を用いることで充放電サイクル中の負極側でのリチウムデンドライト析出を抑制できるためと考えられる。 When γ-Al 2 O 3 particles (average particle size: 5 nm, zeta potential: about −5 mV) are used as the inorganic particles 51, it is possible to increase the number of times of charge and discharge of the secondary battery. Although the exact reason is unclear, it is considered that precipitation of lithium dendrite on the negative electrode side during the charge / discharge cycle can be suppressed by using alumina particles having high reduction resistance.
　無機粒子５１としてＣｅＯ２粒子（ゼータ電位：約３０ｍＶ）やＺｒＯ２粒子（ゼータ電位：約４０ｍＶ）を用いると、高イオン伝導性の電解質層が得られる。無機粒子５１としてＣｅＯ２粒子（ゼータ電位：約３０ｍＶ）やＺｒＯ２粒子（ゼータ電位：約４０ｍＶ）を用いると、高イオン伝導性の半固体電解質が得られる。無機粒子５１としてゼータ電位が高い粒子を用いる場合、粒子表面への有機溶媒分子の吸着が弱まり、有機溶媒分子が比較的自由に熱運動できるようになると考えられる。その結果、有機溶媒分子からリチウムイオンが移動し易くなり、リチウムイオン伝導が促進されたためと考えられる。 When CeO 2 particles (zeta potential: about 30 mV) or ZrO 2 particles (zeta potential: about 40 mV) are used as the inorganic particles 51, an electrolyte layer having high ion conductivity can be obtained. When CeO 2 particles (zeta potential: about 30 mV) or ZrO 2 particles (zeta potential: about 40 mV) are used as the inorganic particles 51, a semi-solid electrolyte having high ion conductivity can be obtained. When particles having a high zeta potential are used as the inorganic particles 51, it is considered that the adsorption of organic solvent molecules to the particle surface is weakened, and the organic solvent molecules can be thermally moved relatively freely. As a result, it is considered that lithium ions easily move from organic solvent molecules, and lithium ion conduction was promoted.
　＜イオン導電材５２＞
　イオン導電材５２は、イオン液体またはイオン液体に類似の性質を示すグライム類およびリチウム塩の混合物である。 <Ion conductive material 52>
The ionic conductive material 52 is an ionic liquid or a mixture of glymes and lithium salts that exhibit similar properties to the ionic liquid.
　イオン液体としては、電解質として機能する公知のイオン液体を利用可能であるが、イオン伝導性（導電性）の観点から、特にＮ，Ｎ－ジエチル－Ｎ－メチル－Ｎ－（２－メトキシエチル）アンモニウムビス（トリフルオロメタンスルホニル）イミド（ＤＥＭＥ－ＴＦＳＩ）を好ましく用いることができる。 As the ionic liquid, a known ionic liquid that functions as an electrolyte can be used. From the viewpoint of ionic conductivity (conductivity), N, N-diethyl-N-methyl-N- (2-methoxyethyl) is particularly preferable. Ammonium bis (trifluoromethanesulfonyl) imide (DEME-TFSI) can be preferably used.
　グライム類（Ｒ－Ｏ（ＣＨ２ＣＨ２Ｏ）ｎ－Ｒ’（Ｒ、Ｒ’は飽和炭化水素、ｎは整数）で表される対称グリコールジエーテルの総称）としては、イオン液体に類似の性質を示す公知のグライム類を利用可能であるが、イオン伝導性（導電性）の観点から、テトラグライム（テトラエチレンジメチルグリコール、Ｇ４）、トリグライム（トリエチレングリコールジメチルエーテル、Ｇ３）、ペンタグライム（ペンタエチレングリコールジメチルエーテル、Ｇ５）、ヘキサグライム（ヘキサエチレングリコールジメチルエーテル、Ｇ６）を好ましく用いることができる。 Glymes (R—O (CH 2 CH 2 O) n—R ′ (R and R ′ are saturated hydrocarbons, n is an integer), a generic name for symmetric glycol diethers) are similar to ionic liquids Known glymes exhibiting properties can be used, but from the viewpoint of ion conductivity (conductivity), tetraglyme (tetraethylene dimethyl glycol, G4), triglyme (triethylene glycol dimethyl ether, G3), pentag lime (penta Ethylene glycol dimethyl ether (G5) and hexaglyme (hexaethylene glycol dimethyl ether, G6) can be preferably used.
　リチウム塩としては、例えば、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＣｌＯ４、ＬｉＣＦ３ＳＯ３、ＬｉＣＦ３ＣＯ２、ＬｉＡｓＦ６、ＬｉＳｂＦ６、リチウムビスオキサレートボラート（ＬｉＢＯＢ）、およびリチウムイミド塩（例えば、リチウムビス（フルオロスルホニル）イミド、ＬｉＦＳＩ）等を好ましく用いることができる。これらのリチウム塩を単独または複数組み合わせて使用してもよい。 Examples of the lithium salt, LiPF 6, LiBF 4, LiClO 4, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, lithium bis oxalate borate (LiBOB), and lithium imide salt (e.g., lithium Bis (fluorosulfonyl) imide, LiFSI) or the like can be preferably used. These lithium salts may be used alone or in combination.
　常温溶融塩、もしくは有機溶媒に対するリチウム塩の混合モル比率は、０．１以上１０以下が好ましい。該範囲よりもリチウム塩比率が高いとリチウム塩の溶解が困難であり、該範囲よりもリチウム塩比率が低いと電解質内のリチウムキャリアが減るため二次電池が低出力となり、二次電池のサイクル特性も低下する。前記混合モル比率は、０．５以上５以下がより好ましく、０．８以上３以下が更に好ましい。 The mixed molar ratio of the lithium salt to the ambient temperature molten salt or the organic solvent is preferably 0.1 or more and 10 or less. If the lithium salt ratio is higher than the range, it is difficult to dissolve the lithium salt. If the lithium salt ratio is lower than the range, the lithium carrier in the electrolyte is reduced, so the secondary battery has a low output, and the cycle of the secondary battery The characteristics are also degraded. The mixing molar ratio is more preferably 0.5 or more and 5 or less, and further preferably 0.8 or more and 3 or less.
　＜電解質バインダ５３＞
　電解質バインダ５３は、フッ素系の樹脂が好適に用いられる。フッ素系の樹脂としては、ＰＶＤＦやＰＴＦＥが好適に用いられる。ＰＶＤＦやＰＴＦＥを用いることで、固体電解質層５０と電極集電体の密着性が向上するため、電池性能が向上する。 <Electrolyte binder 53>
As the electrolyte binder 53, a fluorine-based resin is preferably used. PVDF and PTFE are preferably used as the fluorine-based resin. By using PVDF or PTFE, the adhesion between the solid electrolyte layer 50 and the electrode current collector is improved, so that the battery performance is improved.
　＜固体電解質層５０＞
　固体電解質５５の粉末を成型ダイス等を用いてペレット状に圧縮成型する方法や、電解質バインダ５３を固体電解質５５の粉末に添加・混合し、シート化する方法などがある。固体電解質５５に電解質バインダ５３の粉末を添加・混合することにより、柔軟性の高い固体電解質層５０（電解質シート）を作製できる。または、固体電解質５５に、分散溶媒に電解質バインダ５３を溶解させた結着剤の溶液を添加・混合し、分散溶媒を留去することで、固体電解質層５０を作製できる。 <Solid electrolyte layer 50>
There are a method of compression molding the powder of the solid electrolyte 55 into a pellet using a molding die or the like, and a method of adding and mixing the electrolyte binder 53 to the powder of the solid electrolyte 55 to form a sheet. By adding and mixing the powder of the electrolyte binder 53 to the solid electrolyte 55, a highly flexible solid electrolyte layer 50 (electrolyte sheet) can be produced. Alternatively, the solid electrolyte layer 50 can be produced by adding and mixing a solution of a binder in which the electrolyte binder 53 is dissolved in the dispersion solvent to the solid electrolyte 55 and distilling off the dispersion solvent.
　以下、実施例を挙げて本発明をさらに具体的に説明するが、本発明はこれらの実施例に限定されるものではない。 Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
電極導電材表面におけるＬｉイオンの吸着効果を評価した。有機溶媒にテトラグライム（Ｇ４）、リチウム塩にリチウムビス（トリフルオロスルホニル）イミド（ＬｉＴＦＳＩ）、電極導電剤にアセチレンブラック（平均粒径４８ｎｍ）、結着材にＰＴＦＥを用いて、以下のようにアセチレンブラックと電解液の複合体を作成した。 The adsorption effect of Li ions on the electrode conductive material surface was evaluated. Using tetraglyme (G4) as the organic solvent, lithium bis (trifluorosulfonyl) imide (LiTFSI) as the lithium salt, acetylene black (average particle size 48 nm) as the electrode conductive agent, and PTFE as the binder, as follows: A composite of acetylene black and electrolyte was prepared.
　まず、アセチレンブラックを１２０℃で真空乾燥させた後に、トルエン中にアセチレンブラックを分散させ、１００℃で還流させる。さらに、この混合液中に表面処理剤として３－アミノプロピルトリエトキシシランを加え、均一になるように撹拌しながら６時間還流させる。その後、反応溶液を採取してメタノールで十分に洗浄し、未反応の表面処理剤を水―メタノール溶液で加水分解することによって、表面修飾されたアセチレンブラックを得る。 First, acetylene black is vacuum-dried at 120 ° C., and then acetylene black is dispersed in toluene and refluxed at 100 ° C. Further, 3-aminopropyltriethoxysilane is added as a surface treating agent to the mixed solution, and the mixture is refluxed for 6 hours while stirring uniformly. Thereafter, the reaction solution is collected, washed thoroughly with methanol, and the unreacted surface treatment agent is hydrolyzed with a water-methanol solution to obtain surface-modified acetylene black.
　次に、Ｇ４とＬｉＴＦＳＩとをＧ４：ＬｉＴＦＳＩ＝１：１のモル比率で混合し、電解液（Ｇ４－ＬｉＴＦＳＩ）を作製する。得られた電解液Ｇ４－ＬｉＦＳＩに対して、表面処理を施したアセチレンブラックを体積分率Ｇ４－ＬｉＦＳＩ：アセチレンブラック＝７０：３０（ｖｏｌ％）で混合し、これにメタノールを添加した後に３０分間攪拌する。その後、得られた混合液をシャーレに広げ、メタノールを留去することによって、粉末状の電解液とアセチレンブラックの複合体を得ることができる。 Next, G4 and LiTFSI are mixed at a molar ratio of G4: LiTFSI = 1: 1 to prepare an electrolytic solution (G4-LiTFSI). The obtained electrolytic solution G4-LiFSI was mixed with surface-treated acetylene black at a volume fraction of G4-LiFSI: acetylene black = 70: 30 (vol%), and methanol was added thereto for 30 minutes. Stir. Thereafter, the obtained mixed solution is spread on a petri dish, and methanol is distilled off to obtain a composite of a powdered electrolytic solution and acetylene black.
　混合体中のＬｉイオンの吸着構造を評価するために、分子動力学法を用いた数値シミュレーションを実施した。官能基として３－アミノプロピルトリエトキシシランを用い、グラファイト表面の１平方ナノメートルあたりに、官能基が１．２個配置されるように官能基数を調整した。こうして修飾したグラファイト表面上に、Ｇ４－ＬｉＴＦＳＩ分子を５０個程配置して、周期境界条件の下で分子動力学シミュレーションを実施した。シミュレーションでは、系の温度を２５℃に固定して、一定体積下で２００万ステップの緩和計算を実施した後に、２５０万ステップのサンプリングを行った。これにより、官能基近傍（官能基から０．３ｎｍ）におけるＬｉイオン密度を求めた。 In order to evaluate the adsorption structure of Li ions in the mixture, a numerical simulation using a molecular dynamics method was performed. 3-aminopropyltriethoxysilane was used as a functional group, and the number of functional groups was adjusted so that 1.2 functional groups were arranged per square nanometer on the graphite surface. About 50 G4-LiTFSI molecules were placed on the graphite surface thus modified, and molecular dynamics simulation was performed under periodic boundary conditions. In the simulation, the system temperature was fixed at 25 ° C., and after 2 million steps of relaxation calculations were performed under a certain volume, 2.5 million steps of sampling were performed. This determined the Li ion density in the vicinity of the functional group (0.3 nm from the functional group).
　表面処理剤にジエチルホスフォトエチルトリエトキシシランを用いた以外は、実施例１と同じである。 The same as Example 1 except that diethylphosphotoethyltriethoxysilane was used as the surface treatment agent.
　表面処理剤に３－アミノプロピルトリメトキシシランを用いた以外は、実施例１と同じである。 The same as Example 1 except that 3-aminopropyltrimethoxysilane was used as the surface treatment agent.
　表面処理剤に４－アミノブチルトリエトキシシランを用いた以外は、実施例１と同じである。 The same as Example 1 except that 4-aminobutyltriethoxysilane was used as the surface treatment agent.
　表面処理剤にアミノフェニルトリメトキシシランを用いた以外は、実施例１と同じである。 The same as Example 1 except that aminophenyltrimethoxysilane was used as the surface treatment agent.
　表面処理剤に３－アミノプロピルトリ（メトキシエトキシ）シランを用いた以外は、実施例１と同じである。 The same as Example 1 except that 3-aminopropyltri (methoxyethoxy) silane was used as the surface treatment agent.
　表面処理剤にジフェニルホスフィノエチルジメチルエトキシシランを用いた以外は、実施例１と同じである。 The same as Example 1 except that diphenylphosphinoethyldimethylethoxysilane was used as the surface treatment agent.
　電極導電剤の表面における官能基数（官能基密度）を１平方ナノメートルあたり２．４個とした以外は、実施例１と同じである。 The same as Example 1 except that the number of functional groups (functional group density) on the surface of the electrode conductive agent was 2.4 per square nanometer.
　＜比較例１＞
　電極導電剤の表面にヒドロキシ基を修飾させた以外は、実施例１と同じである。 <Comparative Example 1>
Example 1 is the same as Example 1 except that the surface of the electrode conductive agent is modified with a hydroxy group.
　＜比較例２＞
　電極導電剤の表面における官能基数を１平方ナノメートルあたり４．８個とした以外は、比較例１と同じである。 <Comparative example 2>
The same as Comparative Example 1, except that the number of functional groups on the surface of the electrode conductive agent was 4.8 per square nanometer.
　実施例１～実施例８、比較例１～比較例２の結果を図４に示す。実施例１、実施例２、比較例１、比較例２において、電極導電剤の表面に形成された官能基からの距離が０．３、０．９、１．５ｎｍの３つの領域でＬｉイオン密度を示した。実施例１、実施例２に着目すると、１．５ｎｍから０．３ｎｍのように電極導電剤の表面に近づくにつれて、Ｌｉイオン密度が小さくなっていく様子がわかる。特に、比較例１、比較例２と比べると電極導電剤表面（０．３ｎｍ）におけるＬｉイオン密度は約５０％程度まで減少している。このことは、本実施例によって電極導電剤表面へのＬｉイオン吸着量が抑制されたことを意味しており、Ｌｉイオンが電極内部を自由に運動できるようになったことを意味する。以上から、電極内部におけるＬｉイオン伝導度の低下抑制に効果的であると結論付けられる。 FIG. 4 shows the results of Examples 1 to 8 and Comparative Examples 1 to 2. In Example 1, Example 2, Comparative Example 1, and Comparative Example 2, Li ions were measured in three regions with distances of 0.3, 0.9, and 1.5 nm from the functional group formed on the surface of the electrode conductive agent. The density is shown. Focusing on Example 1 and Example 2, it can be seen that the Li ion density decreases as the surface of the electrode conductive agent is approached, such as from 1.5 nm to 0.3 nm. In particular, compared to Comparative Example 1 and Comparative Example 2, the Li ion density on the electrode conductive agent surface (0.3 nm) is reduced to about 50%. This means that the amount of Li ion adsorption on the surface of the electrode conductive agent was suppressed by this example, and Li ions can move freely inside the electrode. From the above, it is concluded that it is effective for suppressing the decrease in Li ion conductivity inside the electrode.
　また、実施例１～実施例８、比較例１～比較例２のＬｉイオンの吸着量を比較すると、実施例１～実施例８のＬｉイオンの吸着量は比較例１～比較例２のＬｉイオンの吸着量より小さくなっている、具体的には、官能基から０．３ｎｍの平均Ｌｉイオン密度が１．５０ｎｍ－３以下となっているため、実施例１～実施例８がＬｉイオンの吸着抑制に有効であることが分かる。 Further, when the adsorption amounts of Li ions of Examples 1 to 8 and Comparative Examples 1 to 2 are compared, the adsorption amounts of Li ions of Examples 1 to 8 are the same as those of Comparative Examples 1 to 2. More specifically, since the average Li ion density of 0.3 nm from the functional group is 1.50 nm −3 or less, Examples 1 to 8 are Li ions. It turns out that it is effective for adsorption | suction suppression.
１０　　正極集電体
２０　　負極集電体
３０　　電池ケース
４０　　正極合剤層
４２　　正極活物質
４３　　正極導電剤
５０　　固体電解質層
５１　　無機粒子
５２　　イオン導電材
５３　　電解質バインダ
５５　　固体電解質
６０　　負極合剤層
６２　　負極活物質
６３　　負極導電剤
７０　　正極
８０　　負極
９０　　インターコネクタ
１００　全固体電池
２００　バイポーラ型全固体電池 DESCRIPTION OF SYMBOLS 10 Positive electrode collector 20 Negative electrode collector 30 Battery case 40 Positive electrode mixture layer 42 Positive electrode active material 43 Positive electrode conductive agent 50 Solid electrolyte layer 51 Inorganic particle 52 Ion conductive material 53 Electrolyte binder 55 Solid electrolyte 60 Negative electrode mixture layer 62 Negative electrode Active material 63 Negative electrode conductive agent 70 Positive electrode 80 Negative electrode 90 Interconnector 100 All solid state battery 200 Bipolar type all solid state battery

Claims (7)

  1. 　電極活物質、電極導電剤、イオン導電材を含み、
    　前記イオン導電材は前記電極導電剤に保持され、
    　前記電極導電剤の表面に被覆剤が形成され、
    　前記電極導電剤の表面電位は正である二次電池用電極。     Including electrode active material, electrode conductive agent, ionic conductive material,
    The ion conductive material is held by the electrode conductive agent,
    A coating agent is formed on the surface of the electrode conductive agent,
    An electrode for a secondary battery, wherein the electrode conductive agent has a positive surface potential.
  2. 　請求項１の二次電池用電極において、
    　前記被覆剤は、アミノ基およびホスフィン基のいずれか一種以上を含む二次電池用電極。     The electrode for a secondary battery according to claim 1,
    The coating agent is an electrode for a secondary battery containing at least one of an amino group and a phosphine group.
  3. 　請求項２の二次電池用電極において、
    　前記アミノ基または前記ホスフィン基から０．３ｎｍの平均Ｌｉイオン密度が１．５０ｎｍ－３以下である二次電池用電極。     The electrode for a secondary battery according to claim 2,
    An electrode for a secondary battery, wherein an average Li ion density of 0.3 nm from the amino group or the phosphine group is 1.50 nm −3 or less.
  4. 　請求項１の二次電池用電極において、
    　前記電極導電剤の表面における官能基数は、１平方ナノメートル当たり０．０１個以上５個以下である二次電池用電極。     The electrode for a secondary battery according to claim 1,
    The electrode for a secondary battery, wherein the number of functional groups on the surface of the electrode conductive agent is 0.01 or more and 5 or less per square nanometer.
  5. 　請求項１の二次電池用電極において、
    　前記被覆剤は金属酸化物であり、
    　前記被覆剤の表面積は、前記電極導電剤の全表面積の３０％以上７０％以下二次電池用電極。     The electrode for a secondary battery according to claim 1,
    The coating is a metal oxide;
    The surface area of the coating agent is 30% or more and 70% or less of the total surface area of the electrode conductive agent.
  6. 　請求項１の二次電池用電極および固体電解質層を有する二次電池。 A secondary battery comprising the secondary battery electrode and the solid electrolyte layer according to claim 1.
  7. 　電極活物質、電極導電剤、イオン導電材を含む二次電池用電極の製造方法であって、
    　前記イオン導電材は前記電極導電剤に保持され、
    　前記電極導電剤に表面処理剤を導入して前記電極導電剤の表面電位を正にする二次電池用電極の製造方法。     A method for producing an electrode for a secondary battery comprising an electrode active material, an electrode conductive agent, and an ionic conductive material,
    The ion conductive material is held by the electrode conductive agent,
    A method for producing an electrode for a secondary battery, wherein a surface treatment agent is introduced into the electrode conductive agent to make the surface potential of the electrode conductive agent positive.
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