JP2020084041A - Conductive polymer and inorganic solid electrolyte secondary battery - Google Patents

Abstract

To provide a new conductive polymer material giving superior charge-discharge behavior to an inorganic solid electrolyte secondary battery.SOLUTION: A conductive polymer material contains an electron conductivity substance, a lithium salt compound and ion conductive polymer having ethylene oxide unit as side chain.SELECTED DRAWING: None

Description

The present invention relates to a conductive polymer material and an inorganic solid electrolyte secondary battery.

Conventionally, a non-aqueous electrolyte secondary battery typified by a lithium-ion battery has been used as a solution or paste in terms of ion conductivity. However, since there is a risk of equipment damage due to liquid leakage, various safety measures are required, which is a barrier to the development of large batteries.

On the other hand, solid electrolytes in which electrolytes such as polymer solid electrolytes and inorganic solid electrolytes are solidified have been proposed. Polymer solid electrolytes are generally superior in flexibility, bending workability, and moldability, and have the advantage of increasing the degree of freedom in the design of the device to which they are applied, but due to poor load characteristics and low-temperature characteristics, high temperature It has the drawback of being limited to operating battery applications. On the other hand, the inorganic solid electrolyte is higher in ion conductivity than the polymer solid electrolyte, but the electrolyte is crystalline or amorphous, and it is difficult to alleviate the volume change due to the positive and negative electrode active materials during charge and discharge, and However, since the interface resistance between the electrode and the electrolyte is high, there is a problem that the charge/discharge characteristics are insufficient.

For example, Patent Documents 1 and 2 disclose a battery in which a layer of a polymer solid electrolyte containing polyethylene oxide (polyethylene glycol) and a lithium salt is interposed between an inorganic solid electrolyte and an electrode layer. However, polyethylene oxide has high crystallinity and has a melting point of around 60° C., and has a low ionic conductivity below the melting point. In addition, there is a problem that when heated above the melting point, it softens, the strength cannot be maintained, and a short circuit due to breakage easily occurs. Further, the polymer solid electrolyte layer can impart ionic conductivity to the surface of the inorganic solid electrolyte, but cannot impart electron conductivity to the surface of the electrode.

JP, 2014-238925, A JP, 2009-181872, A

The main object of the present invention is to provide a novel conductive polymer material that exhibits excellent charge/discharge characteristics for an inorganic solid electrolyte secondary battery. A further object of the present invention is to provide an inorganic solid electrolyte secondary battery using the conductive polymer material.

The present inventor has diligently studied to solve the above problems. As a result, by disposing an electrically conductive polymer material containing an electronically conductive substance, a lithium salt compound, and an ion conductive polymer having an ethylene oxide unit in a side chain between the electrode and the inorganic solid electrolyte, the inorganic solid electrolyte It was found that the secondary battery exhibits excellent charge/discharge characteristics. The present invention has been completed by further studies based on such findings.

That is, the present invention provides the inventions of the following modes.
Item 1. A conductive polymer material comprising an electron conductive substance, a lithium salt compound, and an ion conductive polymer having an ethylene oxide unit in a side chain.
Item 2. The conductive polymer material according to claim 1, wherein the electronically conductive substance is a carbon material.
Item 3. The lithium salt compounds include LiBF ₄ , LiPF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , LiN(CF ₃ SO ₂ ) ₂ (LiTFSI), LiN(SFO ₂ ) ₂ (LiFSI), LiN(C ₂ F ₅ SO ₂ ). _2, and _{LiN [CF 3 SC (C 2} F 5 SO 2) 3] is at least one selected from the group consisting of _2, a conductive polymer material according to claim 1 or 2.
Item 4. The conductive polymer material according to claim 1, wherein the ion conductive polymer is a polyether having an ethylene oxide unit in a side chain.
Item 5. The conductive polymer material according to any one of claims 1 to 4, wherein the electron conductive substance is contained in an amount of 10 to 1000 parts by mass with respect to 100 parts by mass of the ion conductive polymer.
Item 6. The conductive polymer material according to claim 1, wherein the conductive polymer material is crosslinked.
Item 7. A positive electrode, a negative electrode, an inorganic solid electrolyte secondary battery comprising an inorganic solid electrolyte arranged between these,
The electroconductive polymer material according to any one of claims 1 to 6 is arranged between at least one of the positive electrode and the inorganic solid electrolyte and between the negative electrode and the inorganic solid electrolyte. , Inorganic solid electrolyte secondary battery.

According to the present invention, it is possible to provide a novel conductive polymer material that exhibits excellent charge/discharge characteristics for an inorganic solid electrolyte secondary battery. Furthermore, according to the present invention, it is also possible to provide an inorganic solid electrolyte secondary battery using the conductive polymer material.

The conductive polymer material of the present invention is characterized by containing an electron conductive substance, a lithium salt compound, and an ion conductive polymer having an ethylene oxide unit in a side chain. The conductive polymer material of the present invention, having such a configuration, is excellent in the inorganic solid electrolyte secondary battery when placed between the electrode of the solid electrolyte secondary battery and the inorganic solid electrolyte. Discharge characteristics can be exhibited.

More specifically, the conductive polymer material of the present invention is an electron conductive substance, a lithium salt compound, and an ion conductive polymer having an ethylene oxide unit in a side chain (hereinafter, simply referred to as “ion conductive polymer”). In some cases, it has both electronic conductivity and ionic conductivity. Furthermore, the conductive polymer material of the present invention contains an ion conductive polymer having an ethylene oxide unit in the side chain, and therefore has higher flexibility than an inorganic material. Therefore, the conductive polymer material of the present invention has a large contact area with an electrode (more specifically, an electrode material layer containing active material particles and the like) and an inorganic solid electrolyte, and as a result, with the inorganic solid electrolyte and the electrode. It is considered that the interfacial resistance is effectively reduced and excellent charge/discharge characteristics are exhibited. In addition, as described later, the conductive polymer material of the present invention is preferably disposed between the electrode and the inorganic solid electrolyte and provided so as to be in contact with the electrode material layer. Further, the inorganic solid electrolyte secondary battery may be used in a high temperature environment (for example, a high temperature environment of 100° C. or higher), but by using the conductive polymer material of the present invention, excellent charge/discharge characteristics in the high temperature environment are obtained. Is demonstrated. Hereinafter, the conductive polymer material of the present invention and the inorganic solid electrolyte secondary battery using the same will be described in detail.

In addition, in this specification, the numerical value connected by "-" means the numerical range which includes the numerical value before and behind "-" as a lower limit and an upper limit. When a plurality of lower limit values and a plurality of upper limit values are described separately, arbitrary lower limit values and upper limit values can be selected and connected by "...".

The conductive polymer material of the present invention contains at least an electron conductive substance, a lithium salt compound, and an ion conductive polymer having an ethylene oxide unit in a side chain. Specifically, the conductive polymer material of the present invention is a mixture of an electron conductive substance, a lithium salt compound, and an ion conductive polymer having an ethylene oxide unit in a side chain.

Examples of the ion conductive polymer having an ethylene oxide unit in the side chain include, for example, polyether having an ethylene oxide unit in the side chain, borate ester having an ethylene oxide unit in the side chain, polyolefin having an ethylene oxide unit in the side chain, and the like. Is a polyether having an ethylene oxide unit in the side chain.

The polyether having an ethylene oxide unit in its side chain preferably contains a constitutional unit formed from an epoxy compound having an ethylene oxide unit in its side chain. That is, the ion conductive polymer is preferably a polymer containing at least a monomer of an epoxy compound having an ethylene oxide unit in its side chain.

Examples of the epoxy compound having an ethylene oxide unit in the side chain include a monomer represented by the following formula (2), which is represented by the following formula (2) and, if necessary, the following formula (1) and the following formula (3). The branched polyether using the represented monomer is the polyether (i) having an ethylene oxide unit in the side chain. The monomers represented by the formulas (1) to (3) may be used alone or in combination of two or more.

[In formula (2), R is _{-CH 2 O (CH 2 CH 2} O) n R 4, R 4 is an alkyl group having 1 to 6 carbon atoms, n is the number of 0 to 12. ]

[In the formula (3), R ⁵ represents a group containing an ethylenically unsaturated group. ]

Examples of the monomer of the formula (3) include allyl glycidyl ether, 4-vinylcyclohexyl glycidyl ether, α-terpinyl glycidyl ether, cyclohexenyl methyl glycidyl ether, p-vinylbenzyl glycidyl ether, allylphenyl glycidyl ether, vinyl glycidyl. Ether, 3,4-epoxy-1-butene, 3,4-epoxy-1-pentene, 4,5-epoxy-2-pentene, 1,2-epoxy-5,9-cyclododecanediene, 3,4- Epoxy-1-vinylcyclohexene, 1,2-epoxy-5-cyclooctene, glycidyl acrylate, glycidyl methacrylate, glycidyl sorbate, glycidyl cinnamate, glycidyl crotonic acid, and glycidyl-4-hexenoate are used. Preferred are allyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate.

The polyether (i) having an ethylene oxide unit in its side chain can be synthesized, for example, as follows. Coordination anion initiators such as organoaluminum-based catalyst systems, organozinc-based catalyst systems, and organotin-phosphate ester condensate catalyst systems as ring-opening polymerization catalysts, or potassium containing K ⁺ in the counterion Anion initiators such as alkoxide, diphenylmethyl potassium, and potassium hydroxide are used to react each monomer in the presence or absence of a solvent at a reaction temperature of 10 to 120° C. with stirring to give a polyether (i. ) Is obtained. From the viewpoint of the degree of polymerization or the properties of the copolymer obtained, a coordinating anion initiator is preferable, and an organotin-phosphate ester condensate catalyst system is particularly preferable because it is easy to handle.

In the polyether (i) having an ethylene oxide unit in its side chain, a repeating unit (A) derived from the monomer of formula (1), a repeating unit (B) derived from the monomer of formula (2), The molar ratio of the repeating unit (C) derived from the monomer of the formula (3) is 95 to 5 mol% of (A), 5 to 95 mol% of (B), and 0 to 20 mol% of (C). Suitable, preferably (A) 92-9 mol%, (B) 7-90 mol%, and (C) 1-15 mol%, more preferably (A) 88-18 mol%, (B)10. .About.80 mol %, and (C) 2 to 15 mol %. When the content of the repeating unit (A) is 95 mol% or less, the glass transition temperature is not increased and the oxyethylene chain is not crystallized, and as a result, it is preferable in terms of ion conductivity.

Specific examples of the polyether (i) having an ethylene oxide unit in the side chain include ethylene oxide/diethylene glycol methyl glycidyl ether/allyl glycidyl ether terpolymer, ethylene oxide/diethylene glycol methyl glycidyl ether/glycidyl methacrylate terpolymer, Examples thereof include ethylene oxide/diethylene glycol methyl glycidyl ether/glycidyl acrylate terpolymer.

The weight average molecular weight of the polyether (i) having an ethylene oxide unit in the side chain is not particularly limited, but may be 10,000 to 3,000,000, more preferably 50,000 to 2,500,000, and preferably 100,000 to 2,000,000. It is particularly preferable that The weight average molecular weight is calculated by gel permeation chromatography (GPC) using dimethylformamide (DMF) as a solvent, and is calculated in terms of standard polystyrene.

The content of the ion conductive polymer contained in the conductive polymer material is 100 parts by mass of the entire conductive polymer material, preferably 3 to 95 parts by mass, and more preferably 10 to 90 parts by mass.

The ion conductive polymer may include a crosslinked body.

As the lithium salt compound, a lithium salt compound having a wide potential window, which is generally used for lithium ion batteries, is suitable. Examples of the lithium salt compound include LiBF ₄ , LiPF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , LiN(CF ₃ SO ₂ ) ₂ (LiTFSI), LiN(SFO ₂ ) ₂ (LiFSI), LiN(C ₂ F _{5 ).} SO ₂ ) ₂ , LiN[CF ₃ SC(C ₂ F ₅ SO ₂ ) ₃ ] _{2 and the} like can be mentioned, but the invention is not limited thereto. These may be used alone or in combination of two or more.

As the content of the lithium chloride contained in the conductive polymer material, the value of (mol number of lithium salt compound)/(total mole number of ether oxygen atoms of ion conductive polymer) is preferably 0.0001 to 5, and more preferably 0. The range of 0.001 to 0.5 is preferable.

Further, the conductive polymer material may contain a room temperature molten salt. The room-temperature molten salt is a salt that is at least partially in a liquid state at room temperature, and the room temperature refers to a temperature range in which the power supply is supposed to normally operate. The temperature range in which the power supply is supposed to normally operate has an upper limit of about 120°C, in some cases about 60°C, and a lower limit of about -40°C, and in some cases about -20°C.

Room-temperature molten salts are also called ionic liquids, and pyridine-based, aliphatic amine-based, and alicyclic amine-based quaternary ammonium organic cations are known. Examples of the quaternary ammonium organic cation include imidazolium ions such as dialkylimidazolium and trialkylimidazolium, tetraalkylammonium ions, alkylpyridinium ions, pyrazolium ions, pyrrolidinium ions, piperidinium ions and the like. Particularly, an imidazolium cation is preferable.

Examples of the tetraalkylammonium ion include, but are not limited to, trimethylethylammonium ion, trimethylethylammonium ion, trimethylpropylammonium ion, trimethylhexylammonium ion, tetrapentylammonium ion, and triethylmethylammonium ion. is not.

As the alkylpyridinium ion, N-methylpyridinium ion, N-ethylpyridinium ion, N-propylpyridinium ion, N-butylpyridinium ion, 1-ethyl-2methylpyridinium ion, 1-butyl-4-methyl is used. Examples thereof include, but are not limited to, pyridinium ion and 1-butyl-2,4 dimethylpyridinium ion.

As the imidazolium cation, 1,3-dimethylimidazolium ion, 1-ethyl-3-methylimidazolium ion, 1-methyl-3-ethylimidazolium ion, 1-methyl-3-butylimidazolium ion, 1- Butyl-3-methylimidazolium ion, 1,2,3-trimethylimidazolium ion, 1,2-dimethyl-3-ethylimidazolium ion, 1,2-dimethyl-3-propylimidazolium ion, 1-butyl- Examples thereof include 2,3-dimethylimidazolium ion, but are not limited thereto.

The room temperature molten salt having these cations may be used alone or in combination of two or more kinds.

When the conductive polymer material contains a room temperature molten salt, the content thereof is preferably 10 to 1000 parts by mass, more preferably 20 to 500 parts by mass with respect to 100 parts by mass of the ion conductive polymer.

The conductive polymer material may include a plasticizer and the like. The plasticizer is not particularly limited, but dicyano compounds and branched ether compounds are preferable. When a plasticizer is added, it is preferable to crosslink the ion conductive polymer. This cross-linking is a chemical cross-linking and can suppress the outflow of the plasticizer from the conductive polymer material.

Examples of the dicyano compound include succinonitrile, glutaronitrile, adiponitrile, 1,5-dicyanopentane, 1,6-dicyanohexane, 1,7-dicyanoheptane and 1,8-dicyanooctane. Examples of branched ether compounds include the following multi-branched ether compounds.

When the conductive polymer material contains a plasticizer, the content of the plasticizer is preferably 10 to 1000 parts by mass, more preferably 20 to 500 parts by mass with respect to 100 parts by mass of the ion conductive polymer.

The electron conductive substance may be a carbon material (natural graphite, artificial graphite, amorphous carbon, etc.), an electron conductive polymer, a metal such as gold, or a mixed substance of a carbon material and a metal. Examples of the carbon material include cokes, polymer charcoal, carbon black, carbon fibers, carbon nanotubes, graphene, and graphites. Examples of cokes include coke, petroleum coke and pitch coke, and coal coke. Examples of carbon black include acetylene black and the like. Examples of graphites include artificial graphite and natural graphite. Examples of the electron conductive polymer include polyacene, polythiophene (PEDOT), polyacetylene, polyphenylene vinylene, polypyrrole, polyaniline, polyphenylene sulfide and the like.

The content of the electron conductive substance contained in the conductive polymer material is preferably 10 to 1000 parts by mass, more preferably 20 to 500 parts by mass with respect to 100 parts by mass of the ion conductive polymer.

The conductive polymer material of the present invention is prepared by, for example, mixing an ion conductive polymer, a lithium salt compound, and an electronic conductive substance with an organic solvent and casting the mixture on a substrate (for example, PET film, Teflon (registered trademark) plate, etc.). , Can be prepared by removing the solvent. When the ion conductive polymer is cross-linked, it can be cross-linked by adding a radical initiator, removing the solvent and then applying heat or an active energy ray such as ultraviolet rays. The organic solvent is preferably a polar solvent. Specifically, acetonitrile, ethyl alcohol, methyl alcohol, tetrahydrofuran, dimethylformamide, dimethylsulfoxide, dioxane, methyl ethyl ketone, methyl isobutyl ketone and the like are used alone or in combination.

In the case of crosslinking by heat, a radical initiator selected from organic peroxides, azo compounds and the like is used. As the organic peroxide, ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxyesters and the like which are commonly used for crosslinking are used, and azo compounds are azonitriles. Compounds, azoamide compounds, azoamidine compounds and the like which are usually used for crosslinking are used. The addition amount of the radical initiator varies depending on the type, but is usually within the range of 0.1 to 10 parts by mass with the ion conductive polymer as 100 parts by mass.

As the radical initiator in the case of cross-linking by irradiation with active energy rays, alkylphenone type, benzophenone type, acylphosphine oxide type, titanocenes, triazines, bisimidazoles, oxime esters and the like are used. The addition amount of these radical polymerization initiators varies depending on the type, but is usually within the range of 0.01 to 5.0 parts by mass with 100 parts by mass of the ion conductive polymer.

In the present invention, a crosslinking aid may be used when the conductive polymer material is crosslinked. As a cross-linking aid, ethylene glycol diacrylate, ethylene glycol dimethacrylate, oligoethylene glycol diacrylate, oligoethylene glycol dimethacrylate, trimethylolpropane triacrylate, allyl methacrylate, allyl acrylate, diallyl malate, triallyl isocyanurate, maleimide, phenyl Maleimide, maleic anhydride and the like can be optionally used.

The conductive polymer material of the present invention may be in the form of a film (preferably a crosslinked film of a conductive polymer material), and the film thickness is preferably 0.1 μm to 200 μm, more preferably 0.5 μm to 100 μm. It is within the range.

Inorganic solid electrolyte secondary battery The inorganic solid electrolyte secondary battery of the present invention is a positive electrode, a negative electrode, and an inorganic solid electrolyte secondary battery provided with an inorganic solid electrolyte arranged therebetween, the positive electrode and the inorganic solid. The conductive polymer material of the present invention is disposed between the electrolyte and at least one of the negative electrode and the inorganic solid electrolyte. The conductive polymer material of the present invention is as described above.

As described above, the conductive polymer material used in the inorganic solid electrolyte secondary battery of the present invention contains an electron conductive substance, a lithium salt compound, and an ion conductive polymer having an ethylene oxide unit in its side chain. Therefore, it has both electronic conductivity and ionic conductivity. Furthermore, since the conductive polymer material contains an ion conductive polymer having an ethylene oxide unit in its side chain, it has higher flexibility than an inorganic material. Therefore, in the inorganic solid electrolyte secondary battery of the present invention, the conductive polymer material, the electrode (more specifically, the electrode material layer containing active material particles and the like) and the inorganic solid electrolyte (aggregate of inorganic particles) It is considered that the contact area becomes large, and as a result, the interfacial resistance between the electrode and the inorganic solid electrolyte is effectively reduced, and excellent charge/discharge characteristics are exhibited. In particular, in the inorganic solid electrolyte secondary battery of the present invention, the conductive polymer material is preferably arranged between the electrode and the inorganic solid electrolyte and provided so as to be in contact with the electrode material layer.

Further, the inorganic solid electrolyte secondary battery of the present invention may be used in a high temperature environment (for example, a high temperature environment of 100° C. or higher), but by using the conductive polymer material of the present invention, it is excellent in a high temperature environment. Charge/discharge characteristics are exhibited.

In the inorganic solid electrolyte secondary battery of the present invention, an ion conductive polymer material containing a lithium salt compound and an ion conductive polymer having an ethylene oxide unit in a side chain is arranged between the conductive polymer material and the inorganic solid electrolyte. It is also preferable to In the ion conductive polymer material, the lithium salt compound and the ion conductive polymer are the same as the conductive polymer material, respectively.

The ion conductive polymer is preferably a crosslinked film. The crosslinked film of an ion conductive polymer is formed by crosslinking at least a composition containing a lithium salt compound and an ion conductive polymer having an ethylene oxide unit in a side chain. That is, the crosslinked film is a crosslinked film of a composition containing a lithium salt compound and an ion conductive polymer. The lithium salt compound and the ion conductive polymer are as described above.

The content of the ion conductive polymer contained in the crosslinked film is preferably 10 to 90 parts by mass, more preferably 20 to 80 parts by mass, based on 100 parts by mass of the entire crosslinked film.

The content of lithium chloride contained in the crosslinked film is preferably 0.0001 to 5, more preferably 0.001 to 0. 5, the number of moles of lithium salt compound/the total number of moles of ether oxygen atoms of the ion conductive polymer. A range of 5 is good.

Further, the crosslinked film may contain a room temperature molten salt. The room temperature molten salt is as described above.

When the crosslinked film contains a room temperature molten salt, the content thereof is preferably 10 to 1000 parts by mass, more preferably 20 to 500 parts by mass, relative to 100 parts by mass of the ion conductive polymer.

The crosslinked film may contain a plasticizer and the like. The plasticizer is as described above.

When the crosslinked film contains a plasticizer, the content of the plasticizer is preferably 10 to 1000 parts by mass, and more preferably 20 to 500 parts by mass with respect to 100 parts by mass of the ion conductive polymer.

A reaction initiator or a crosslinking aid may be added to the composition containing the lithium salt compound and the ion conductive polymer to form a crosslinked film. Examples of the reaction initiator include a thermal reaction initiator and a photoreaction initiator.

As the thermal reaction initiator, a radical initiator selected from organic peroxides, azo compounds and the like is used. As the organic peroxide, ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxyesters and the like which are commonly used for crosslinking are used, and azo compounds are azonitriles. Compounds, azoamide compounds, azoamidine compounds and the like which are usually used for crosslinking are used. The addition amount of the radical initiator varies depending on the type, but is usually within the range of 0.1 to 10 parts by mass with the ion conductive polymer as 100 parts by mass.

As the photoreaction initiator, radical initiators such as alkylphenone series, benzophenone series, acylphosphine oxide series, titanocenes, triazines, bisimidazoles, and oxime esters are used. The addition amount of these radical polymerization initiators varies depending on the type, but is usually within the range of 0.01 to 5.0 parts by mass with 100 parts by mass of the ion conductive polymer.

As the crosslinking aid, ethylene glycol diacrylate, ethylene glycol dimethacrylate, oligoethylene glycol diacrylate, oligoethylene glycol dimethacrylate, trimethylolpropane triacrylate, allyl methacrylate, allyl acrylate, diallyl malate, triallyl isocyanurate, maleimide , Phenylmaleimide, maleic anhydride, etc. can be optionally used.

An organic solvent may be added to the composition containing the lithium salt compound and the ion conductive polymer, and as the organic solvent, toluene, xylene, benzene, acetonitrile, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, THF ( Tetrahydrofuran).

The crosslinked film is produced by, for example, mixing an ion conductive polymer, a reaction initiator if necessary, and a lithium salt compound in an organic solvent and dissolving them to form a composition, and then forming a composition on a substrate (for example, PET film or Teflon). (Registered trademark) plate, etc., the composition is cast, the solvent is removed, and then a crosslinked film is produced by heating or irradiation with active energy rays such as ultraviolet rays. Alternatively, the composition may be directly cast on the surface of the inorganic solid electrolyte to produce a crosslinked film.

The thickness of the crosslinked film is preferably in the range of 0.1 μm to 200 μm, more preferably 0.5 μm to 100 μm.

Examples of the laminated structure of the inorganic solid electrolyte secondary battery of the present invention include the following structures.
A laminated structure in which a positive electrode, a conductive polymer material, an ion conductive polymer material, an inorganic solid electrolyte, an ion conductive polymer material, a conductive polymer material, and a negative electrode are sequentially stacked;
A laminated structure in which a positive electrode, a conductive polymer material, an ion conductive polymer material, an inorganic solid electrolyte, an ion conductive polymer material, and a negative electrode are sequentially stacked.
A laminated structure in which a positive electrode, a conductive polymer material, an inorganic solid electrolyte, an ion conductive polymer material, a conductive polymer material, and a negative electrode are laminated in this order;
A laminated structure in which a positive electrode, a conductive polymer material, an ion conductive polymer material, an inorganic solid electrolyte, and a negative electrode are laminated in this order;
A laminated structure in which a positive electrode, an inorganic solid electrolyte, an ion conductive polymer material, a conductive polymer material, and a negative electrode are laminated in this order;
A laminated structure in which a positive electrode, a conductive polymer material, an inorganic solid electrolyte, a conductive polymer material, and a negative electrode are sequentially stacked;
A laminated structure in which a positive electrode, a conductive polymer material, an inorganic solid electrolyte, and a negative electrode are sequentially laminated;
A laminated structure in which a positive electrode, an inorganic solid electrolyte, a conductive polymer material, and a negative electrode are sequentially laminated.

The ion conductive polymer material is preferably in the form of a film (preferably a crosslinked film), and the thickness of the film of the ion conductive polymer material is preferably 0.1 to 200 μm, more preferably 0.5 to 100 μm. is there.

In the inorganic solid electrolyte secondary battery of the present invention, known materials can be used for both the positive electrode and the negative electrode, but an electrode having an electrode material layer, that is, a positive electrode material layer or a negative electrode material layer on the current collector may be exemplified. it can.

A known current collector can be used for the positive electrode and the negative electrode. Specifically, for the positive electrode, a metal such as aluminum, nickel, stainless steel, gold, platinum, or titanium is used as a current collector. For the negative electrode, a metal such as copper, nickel, stainless steel, gold, platinum or titanium is used as a current collector.

Further, the positive electrode material layer and the negative electrode material layer each contain at least a positive electrode active material and a negative electrode active material, and may further contain a conductive auxiliary agent, a binder, and a thickener, if necessary, the above-mentioned inorganic material. A solid electrolyte may be included.

The positive electrode active material used in the present invention is a lithium metal-containing composite oxide powder having a composition of any one of LiMO ₂ , LiM ₂ O ₄ , Li ₂ MO ₃ and LiMEO ₄ . Here, M in the formula is mainly composed of a transition metal and contains at least one of Co, Mn, Ni, Cr, Fe, and Ti. Although M is a transition metal, Al, Ga, Ge, Sn, Pb, Sb, Bi, Si, P, B and the like may be added in addition to the transition metal. E contains at least one of P and Si. The particle size of the positive electrode active material is preferably 50 μm or less, more preferably 20 μm or less. These active materials have an electromotive force of 3 V (vs. Li/Li+) or more.

Specific examples of the positive electrode active material include lithium cobalt oxide, lithium nickel oxide, nickel/cobalt/lithium manganate (ternary system), spinel type lithium manganate, and lithium iron phosphate.

The negative electrode active material used in the present invention is a carbon material (natural graphite, artificial graphite, amorphous carbon, etc.) having a structure (intercalation compound) capable of occluding and releasing alkali metal ions such as lithium ions, or lithium ions. Metals such as lithium, aluminum-based compounds, tin-based compounds, silicon-based compounds, and titanium-based compounds that can store and release alkali metal ions such as. In the case of powder, the particle size is preferably 10 nm or more and 100 μm or less, and more preferably 20 nm or more and 20 μm or less. Moreover, you may use as a mixed active material of a metal and a carbon material.

When using a conductive auxiliary agent, a known conductive auxiliary agent can be used, such as graphite, furnace black, acetylene black, conductive carbon black such as Ketjen black, carbon fiber such as carbon nanotubes, or metal powder. Can be mentioned. These conductive aids may be used alone or in combination of two or more.

As the binder, for example, one or more selected from fluororesins such as PVdF, fluororubber and acrylic rubber, modified acrylic rubber, styrene-butadiene rubber, acrylic polymers, vinyl polymers and the above-mentioned ion conductive polymers. Compounds can be used. These binders are preferably added in an amount of 5 parts by mass or less, more preferably 3 parts by mass or less, for example 0.01 to 2 parts by mass, based on 100 parts by mass of the active material.

Specific examples of the thickener include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose and salts thereof (alkali metal salts such as sodium salts, ammonium salts), polyvinyl alcohol, polyacrylic acid salts, polyethylene oxide and the like. You may use these thickeners 1 type(s) or 2 or more types. These thickeners are added with the active material as 100 parts by mass, preferably 5 parts by mass or less, more preferably 3 parts by mass or less, for example, 0.01 to 2 parts by mass. Further, when the viscosity of the coating liquid is low, a thickener can be used together.

The method for producing the positive electrode and the negative electrode including the current collector, the positive electrode material layer and the negative electrode material layer is not particularly limited, and a general method is used. For example, a positive electrode active material or a negative electrode active material, a conductive auxiliary agent, a binder, a solvent such as water or N-methyl-2-pyrrolidone (NMP), and a positive electrode material and a negative electrode material paste (thickener, if necessary) ( The coating solution) is uniformly applied to the surface of the current collector by a doctor blade method or a silk screen method so as to have an appropriate thickness.

For example, in the doctor blade method, a negative electrode active material powder, a positive electrode active material powder, a conductive auxiliary agent, a binder, etc. are dispersed in water to form a slurry, which is applied to a metal electrode substrate, and then a blade having a predetermined slit width is used. Make it uniform in thickness. After applying the active material, the electrode is dried, for example, in hot air at 100° C. or under reduced pressure at 80° C. to remove excess organic solvent. The dried electrode is press-molded by a press machine to manufacture the electrode.

When the positive electrode material layer and the negative electrode material layer are formed on the current collector, voids are generated between the positive electrode material layer and the negative electrode material electrode material, for example, between the active materials, between the active material and another electrode material, and the like. It will be. In the inorganic solid electrolyte secondary battery of the present invention, such voids may contain an ion conductive polymer, a lithium salt compound, or the like.

Examples of the inorganic solid electrolyte include oxide-based solid electrolytes and sulfide-based solid electrolytes. The inorganic solid electrolyte is generally an aggregate of inorganic solid particles forming the electrolyte.

The oxide solid electrolyte is particularly limited as long as it contains oxygen, has ion conductivity of a metal belonging to Group 1 or 2 of the periodic table, and has electronic insulation. Not a thing.

Specific compounds included in the oxide-based solid electrolyte, Li _x La _y TiO ₃ [x = 0.3~0.7, y = 0.3~0.7] (LLT), Li _x La _y Zr _z M _m O _n (M is at least one element of Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, Sn, and x satisfies 5≦x≦10, and y satisfies 1 ≦ y ≦ 4, z satisfies 1 ≦ z ≦ 4, m satisfies 0 ≦ m ≦ 2, n satisfies 5 ≦ n ≦ 20.) Li x B y M z O n ( wherein Medium M is at least one element of C, S, Al, Si, Ga, Ge, In, Sn, x satisfies 0≦x≦5, y satisfies 0≦y≦1, and z is 0. meet ≦ z ≦ 1, n satisfies 0 ≦ n ≦ 6.), Li x (Al, Ga) y (Ti, Ge) z Si a P m O n ( however, 1 ≦ x ≦ 3,0 ≦ y≦1, 0≦z≦2, 0≦a≦1, 1≦m≦7, 3≦n≦13), Li _(3-2x) M _x DO (x is a number from 0 to 0.1 _). , M represents a divalent metal atom, D represents a halogen atom or a combination of two or more kinds of halogen atoms), Li _x Si _y O _z (1≦x≦5, 0<y≦3, 1) ≦z≦10), Li _x S _y O _z (1≦x≦3, 0<y≦2, 1≦z≦10), Li ₃ BO ₃ —Li ₂ SO ₄ , Li ₂ O—B ₂ O _{3 -P 2 O 5, Li 2 O} -SiO 2, Li 6 BaLa 2 Ta 2 O 12, Li 3 PO (4-3 / 2w) N w (w is w <1), LISICON (Lithium super ionic conductor) type Li _3.5 Zn _0.25 GeO ₄ having a crystal structure, La _0.55 Li _0.35 TiO ₃ having a perovskite type crystal structure, LiTi ₂ P ₃ O ₁₂ having a NASICON (Naturium super ionic conductor) type crystal structure, Li _{(1+x+y) )} (Al, Ga) _x (Ti, Ge) _(2-x) Si _y P _(3-y) O ₁₂ (where 0≦x≦1, 0≦y≦1), Li having a garnet-type crystal structure ₇ La ₃ Zr ₂ O _{12 and the} like can be mentioned. A phosphorus compound containing Li, P and O is also desirable. For example, lithium phosphate (Li ₃ PO ₄ ), LiPON and LiPOD (D is Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb) in which a part of oxygen of lithium phosphate is replaced with nitrogen. , Mo, Ru, Ag, Ta, W, Pt, Au and the like) and the like. LiAON (A is at least one selected from Si, B, Ge, Al, C, Ga, etc.) and the like can also be preferably used.

Among them, Li _x La _y TiO ₃ [x = 0.3~0.7, y = 0.3~0.7] _{(LLT), Li x La y} Zr z M m O n (M is Al, Mg , Ca, Sr, V, Nb, Ta, Ti, Ge, In, Sn, and at least one element, x satisfies 5≦x≦10, y satisfies 1≦y≦4, and z is 1 ≦z≦4, m satisfies 0≦m≦2, and n satisfies 5≦n≦20), Li ₇ La ₃ Zr ₂ O ₁₂ (LLZ), Li ₃ BO ₃ , Li ₃ BO _{3 -Li 2 SO 4, Li 3 BO} 3 -Li 2 CO 3, Li x (Al, Ga) y (Ti, Ge) z Si a P m O n ( however, 1 ≦ x ≦ 3,0 ≦ y ≦ 1 , 0≦z≦2, 0≦a≦1, 1≦m≦7, 3≦n≦13) are preferable. These may be used alone or in combination of two or more.

The sulfide-based solid electrolyte is not particularly limited as long as it contains sulfur, has ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and has electronic insulation. Not a thing. For example, a lithium ion conductive inorganic solid electrolyte satisfying the composition represented by the following formula can be given.

Li _a M _b P _c S _d A _e

In the formula, M represents an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al and Ge. Among them, B, Sn, Si, Al and Ge are preferable, and Sn, Al and Ge are more preferable. A represents I, Br, Cl or F, preferably I or Br, and particularly preferably I. a to e indicate the composition ratio of each element, and a:b:c:d:e satisfies 1 to 12:0 to 1:1:2 to 12:0 to 5. Further, a is preferably 1 to 9, and more preferably 1.5 to 4. b is preferably 0 to 0.5. 3-7 are preferable and, as for d, 3.25-4.5 are more preferable. Further, e is preferably 0 to 3, and more preferably 0 to 2.

In the formula, the composition ratio of Li, M, P, S and A is preferably b and e being 0, more preferably b=0, e=0 and the ratio of a, c and d (a:c). :D) is a:c:d=1 to 9:1:3 to 7, more preferably b=0, e=0 and a:c:d=1.5 to 4:1:3. 25-4.5.

When the inorganic solid electrolyte is in the form of particles, its particle size is, for example, 0.01 to 100 μm, preferably 0.1 to 20 μm.

Manufacturing method of inorganic solid electrolyte secondary battery The manufacturing method of the inorganic solid electrolyte secondary battery of the present invention is not particularly limited, at least a positive electrode, a negative electrode, an inorganic solid electrolyte, and composed of a conductive polymer material of the present invention, known It is manufactured by the method. For example, in the case of a coin-type lithium-ion battery, a conductive polymer material is arranged on at least one of the positive electrode, the inorganic solid electrolyte, the negative electrode, the positive electrode and the inorganic solid electrolyte, and the negative electrode and the inorganic solid electrolyte. Then, insert it in the outer can. After that, the storage body is obtained by joining the sealing body with tab welding or the like, enclosing the sealing body, and caulking. The shape of the battery is not limited, but examples thereof include a coin type, a cylinder type, and a sheet type, and a structure in which two or more batteries are laminated may be used.

The present invention will be described more specifically in the following examples, but the present invention is not limited thereto.

In this example, a coin battery was prepared using a conductive polymer material, and the performance of charge/discharge characteristics of the coin battery was evaluated in the following experiment.

[Evaluation of fabricated battery]
For the evaluation of the manufactured battery, a charge/discharge test was performed using a charge/discharge device, and the charge capacity and the discharge capacity were obtained.

Charge/discharge measurement After CCCV charging (0.01C cut) up to 4.2V with a current equivalent to 0.1C (10 hour rate), CCCV discharge (0.01C cut) up to 2.5V with a current corresponding to 0.1C. ) Was done. The test temperature was 100° C. environment.

[Example of producing positive electrode]
100 parts by mass of NCM (nickel/cobalt/lithium manganate=5/2/3) as a positive electrode active material, 1 part by mass of vapor-grown carbon fiber (VGCF) as a conduction aid, 8 parts by mass of PVdF as a binder, and ion conductivity Ethylene oxide/diethylene glycol methyl glycidyl ether/allyl glycidyl ether=80/17/3 mol% terpolymer (weight average molecular weight 1,220,000) 10 parts by mass as a polymer, and lithium borofluoride 3 parts by mass as a lithium salt compound were further added. The slurry was added to the NMP solution so that the solid content concentration of the slurry was 40% by mass, and sufficiently mixed to obtain a positive electrode slurry. The obtained positive electrode slurry is applied onto an aluminum current collector having a thickness of 20 μm using a die coater, dried and dried at 100° C. for 12 hours or more, and then pressed by a roll press machine to produce a positive electrode having a thickness of 20 μm. did.

[Exemplary Production Example of Conductive Polymer Material (Crosslinked Film)]
As an ion conductive polymer having an ethylene oxide unit in the side chain, as a lithium salt compound in 100 parts by mass of ethylene oxide/diethylene glycol methyl glycidyl ether/allyl glycidyl ether=80/17/3 mol% terpolymer (weight average molecular weight of 1020,000) 15 parts by mass of LiBF _4, 85 parts by mass of acetylene black as a carbon material, 85 parts by mass of vapor grown carbon fiber (VGCF), 10 parts by mass of trimethylolpropane triacrylate as a cross-linking aid, and benzoyl peroxide (as a radical initiator) 0.3 part by mass of Niiper BMT, manufactured by NOF CORPORATION) was further added to the acetonitrile solution so that the solid component concentration of the slurry was 50% by mass, and sufficiently mixed to obtain a slurry solution. This slurry solution is applied onto a PET film, dried, and then thermally crosslinked at 100° C. for 2 hours under reduced pressure to give a crosslinked film of a conductive polymer material having a thickness of 20 μm and having both electron conductivity and ion conductivity. Got

[Example of Preparation of Ion Conductive Polymer Material (Crosslinked Film)]
100 parts by mass of ethylene oxide/diethylene glycol methyl glycidyl ether/allyl glycidyl ether=80/17/3 mol% terpolymer (weight average molecular weight 1.5 million) as an ion conductive polymer, and 38 parts by mass of LiTFSI as a lithium salt compound are crosslinked. 10 parts by mass of trimethylolpropane triacrylate as an auxiliary agent and 0.3 parts by mass of benzoyl peroxide (Nyper BMT, manufactured by NOF CORPORATION) as a radical initiator were completely dissolved in 900 parts by mass of acetonitrile to form a coating solution. Prepared. This coating solution was applied onto a PET film, dried, and then thermally crosslinked at 100° C. for 2 hours under reduced pressure to obtain a crosslinked film of an ion conductive polymer material containing a lithium salt compound having a thickness of 20 μm.

[Practical preparation example of inorganic solid electrolyte]
(1) 0.5 parts by mass of lithium borate was dissolved in 99.5 parts by mass of ion-exchanged water to prepare a 0.5% by mass aqueous solution of lithium borate. Separately, 0.5 parts by mass of lithium sulfate monohydrate was dissolved in 99.5 parts by mass of ion-exchanged water to prepare a 0.5 mass% lithium sulfate aqueous solution. 13 parts by mass of a 0.5% by mass aqueous solution of lithium sulfate was added to 100 parts by mass of a 0.5% by mass aqueous solution of lithium borate, and further, an oxide solid electrolyte LATP (manufactured by Toshima Seisakusho) (composition: Li _1.3 Al _0.3 11.7 parts by mass of Ti _1.7 P ₃ O ₁₂ , average particle size: 1 μm) was added, and the mixture was stirred at room temperature. This slurry was transferred to a rotary evaporator equipped with a 60° C. water bath, and the solvent was distilled off and dried under heating, stirring, and reduced pressure to obtain a white dry product. This was vacuum dried at 150° C. for 1 hour to obtain a dry product of LATP (inorganic solid electrolyte) coated with 5% by mass of lithium borate-lithium sulfate.

(2) 100 parts by mass of ethylene oxide/diethylene glycol methyl glycidyl ether/allyl glycidyl ether=80/17/3 mol% terpolymer (weight average molecular weight 1.5 million) as an ion conductive polymer, and lithium borofluoride 12 as a lithium salt compound. Parts by mass, 10 parts by mass of trimethylolpropane triacrylate as a cross-linking aid, and 0.3 parts by mass of benzoyl peroxide (Nyper BMT, manufactured by NOF CORPORATION) as a radical initiator are stirred in acetonitrile at room temperature for 10 hours. Then, it was completely dissolved to prepare an acetonitrile solution containing a polymer solid electrolyte of 0.5% by mass of branched polyether.

(3) To 100 parts by mass of an acetonitrile solution containing the polymer solid electrolyte of 0.5% by mass of branched polyether of (2), 8.7 parts by mass of the dried inorganic solid electrolyte of (1) is added, Using a rotary evaporator equipped with a water bath at 60°C, the solvent was distilled off under heating, stirring and reduced pressure to dryness. The dried product was vacuum dried at 110° C. for 2 hours to obtain a white dried product. 39 mg of the dried powder was put into a tablet forming die having a diameter of 10 mmφ and pressed at 20 kN for 5 minutes to obtain a molded product having a thickness of 230 μm.

[Comparative Preparation Example of Conductive Polymer Material (Crosslinked Film)]
15 parts by mass of LiBF ₄ as a lithium salt compound, 85 parts by mass of acetylene black as a carbon material, and 85 parts by mass of vapor grown carbon fiber (VGCF) were added to 100 parts by mass of polyethylene oxide (weight average molecular weight: 1.1 million), and further slurry It was added to an acetonitrile solution so that the solid component concentration was 50% by mass, and sufficiently mixed to obtain a slurry solution. This slurry solution was applied onto a PET film and dried to obtain a 22 μm-thick crosslinked film of a conductive polymer material having both electron conduction and ion conduction.

Battery Production Example [Inorganic Solid Electrolyte Secondary Battery Implementation Production Example 1]
In a dry room, the positive electrode obtained in the preparation example, the conductive polymer material of the practical preparation example, the ion conductive polymer material of the practical preparation example, the inorganic solid electrolyte of the practical preparation example, the ion conductive polymer material of the practical preparation example, the negative electrode After laminating in order of (metal lithium foil), caulking was performed to manufacture a test 2032 type coin battery.
<Charging/discharging conditions>
Lower limit voltage 2.5V-upper limit voltage 4.2V, 100°C
CC(0.1C)-CV(0.01C) charge CC(0.1C)-CV(0.01C) discharge <charge/discharge test result>
Charge capacity 140 mAh/g, discharge capacity 110 mAh/g

[Comparative Production Example 1 of Inorganic Solid Electrolyte Secondary Battery]
In Comparative Production Example 1, a 2032 type coin battery for test was prepared in the same manner as in Experimental Production Example 1 except that the conductive polymer material of Comparative Production Example was used instead of the conductive polymer material of Experimental Production Example 1. Manufactured.
<Charging/discharging conditions>
Lower limit voltage 2.5V-upper limit voltage 4.2V, 100°C
CC(0.1C)-CV(0.01C) charge CC(0.1C)-CV(0.01C) discharge <charge/discharge test result>
Charge capacity 105 mAh/g, discharge capacity 95 mAh/g.

[Comparative Production Example 2 of Inorganic Solid Electrolyte Secondary Battery]
In Comparative Production Example 2, a 2032 type coin battery for test was produced in the same manner as in Experimental Production Example 1 except that the conductive polymer material of Experimental Production Example 1 was not used.
<Charging/discharging conditions>
Lower limit voltage 2.5V-upper limit voltage 4.2V, 100°C
CC(0.1C)-CV(0.01C) charge CC(0.1C)-CV(0.01C) discharge <charge/discharge test result>
Charge capacity 100 mAh/g, discharge capacity 90 mAh/g.

From the results of the examples, by inserting a conductive polymer material having both electronic conduction and ionic conduction between the electrode and the inorganic solid electrolyte, the inorganic solid electrolyte secondary battery has excellent charge/discharge characteristics (charge and discharge capacity). ) Is demonstrated.

The conductive polymer material of the present invention can exhibit excellent charge/discharge characteristics by being arranged between the electrode of the inorganic solid electrolyte secondary battery and the inorganic solid electrolyte, and can be used in electric vehicles, hybrid electric vehicles, etc. Can be suitably used for large-scale battery applications such as in-vehicle applications and storage batteries for household power storage.

Claims (7)

A conductive polymer material comprising an electron conductive substance, a lithium salt compound, and an ion conductive polymer having an ethylene oxide unit in a side chain. The conductive polymer material according to claim 1, wherein the electronically conductive substance is a carbon material. The lithium salt compounds include LiBF ₄ , LiPF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , LiN(CF ₃ SO ₂ ) ₂ (LiTFSI), LiN(SFO ₂ ) ₂ (LiFSI), LiN(C ₂ F ₅ SO ₂ ). _2, and _{LiN [CF 3 SC (C 2} F 5 SO 2) 3] is at least one selected from the group consisting of _2, a conductive polymer material according to claim 1 or 2. The conductive polymer material according to claim 1, wherein the ion conductive polymer is a polyether having an ethylene oxide unit in a side chain. The conductive polymer material according to any one of claims 1 to 4, wherein the electron conductive substance is contained in an amount of 10 to 1000 parts by mass with respect to 100 parts by mass of the ion conductive polymer. The conductive polymer material according to claim 1, wherein the conductive polymer material is crosslinked. A positive electrode, a negative electrode, an inorganic solid electrolyte secondary battery comprising an inorganic solid electrolyte arranged between these,
The electroconductive polymer material according to any one of claims 1 to 6 is arranged between at least one of the positive electrode and the inorganic solid electrolyte and between the negative electrode and the inorganic solid electrolyte. , Inorganic solid electrolyte secondary battery.