Solid electrolyte and solid electrolyte battery

Abstract

To provide a solid electrolyte and a solid electrolyte battery having superior humidity resistance.SOLUTION: This solid electrolyte comprises a matrix containing lithium, a metal element, and a halogen, and a modified layer formed on the surface of the matrix, wherein the matrix contains lithium, the metal element, and the halogen, wherein the metal element is at least one selected from the group consisting of Mg, Al, Sc, Y, Nb, Zr, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, In, Sn, Ta, W, and lanthanoids, and the modified layer includes an oxide containing the metal element and the halogen.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a solid electrolyte and a solid electrolyte battery. [Background technology]

[0002] In recent years, electronics technology has made remarkable progress, with efforts being made to make portable electronic devices smaller, lighter, thinner, and more multifunctional. There is also a strong demand for batteries, which serve as the power source for electronic devices, to be smaller, lighter, thinner, and more reliable. For this reason, solid electrolyte batteries, which use a solid electrolyte as the electrolyte, have attracted attention.

[0003] The solid electrolyte may be an oxide-based solid electrolyte, a sulfide-based solid electrolyte, a complex hydride-based solid electrolyte, a halide-based solid electrolyte, or the like. 2+a E 1-b+α G b X d The halide-based solid electrolyte has better oxidation resistance than oxide-based solid electrolytes, sulfide-based solid electrolytes, complex hydride-based solid electrolytes, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 024783 Summary of the Invention [Problem to be solved by the invention]

[0005] When a halide-based solid electrolyte is exposed to a moisture-containing environment, the ionic conductivity of the solid electrolyte may decrease.

[0006] The present disclosure has been made in view of the above-mentioned problems, and has an object to provide a solid electrolyte and a solid electrolyte battery that are excellent in moisture resistance. [Means for solving the problem]

[0007] A solid electrolyte according to a first aspect includes a matrix containing lithium, a metal element, and a halogen, and a modified layer formed on the surface of the matrix. The matrix contains lithium, a metal element, and a halogen. The metal element is any one selected from the group consisting of Mg, Al, Sc, Y, Nb, Zr, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, In, Sn, Ta, W, and lanthanides. The modified layer includes an oxide containing the metal element and the halogen.

[0008] In the solid electrolyte according to the above aspect, the matrix may be represented by the following formula (1): A a E b G c X d ···(1) In formula (1), A is at least one element selected from the group consisting of Li, Cs, Ca, Rb, Sr, and Ba; E is at least one element selected from the group consisting of Mg, Al, Sc, Y, Nb, Zr, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, In, Sn, Ta, W, and lanthanoids; and G is O, OH, BO2, BO3, BO4, BO6, BO7, CO3, NO3, AlO2, SiO3, SiO4, SiO7, SiO9, SiO 11 , SiO 18 , PO3, PO4, P2O7, P3O 10, SO3, SO4, SO5, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, BF4, PF6, B((COO)2), (COO)2, N, AlCl4, CF3SO3, CH3COO, CF3COO, OOC-(CH2)2-COO, OOC-CH2-COO, OOC-CH(OH)-CH(OH)-COO, OOC-CH(OH)-CH2-COO, C6H5SO3, OOC-CH=CH-COO (maleate), OOC-CH=CH-COO (fumarate), C(OH)(CH2COOH)2COO, AsO4, BiO4, CrO4, MnO4, PtF6, PtCl6, PtBr6, PtI6, SbO4, SeO4, TeO4, HCOO, SCN, NH2, CH3O, CH3CH2O, O-(CH2)-O (ethylene glycolate), O-CH2-CH(OH)-CH2-O (glycerolate), OOCCH2COO (malonate), ethylenediamine tetraacetate, citrate, nitrilotriacetate, penicillamineate, dimercapto - l ate, cyclopentadienyl, and is at least one group selected from the group consisting of; X is at least one element selected from the group consisting of F, Cl, Br, and I; a satisfies 0.5 ≦ a < 6; b satisfies 0 < b < 2; c satisfies 0 ≦ c < 6.0; and d satisfies 0 ≦ d ≦ 6.1.

[0009] In formula (1) of the solid electrolyte according to the above aspect, E may contain Zr.

[0010] In the solid electrolyte according to the above aspect, the modified layer may further contain sulfur.

[0011] In the solid electrolyte according to the above aspect, the thickness of the modified layer may be 1 nm or more and 1000 nm or less.

[0012] The solid electrolyte battery according to the second aspect includes a positive electrode, a negative electrode, and a solid electrolyte layer sandwiched between the positive electrode and the negative electrode. At least one of the positive electrode, the negative electrode, and the solid electrolyte layer contains the solid electrolyte according to the above aspect.

Advantages of the Invention

[0013] The solid electrolyte according to this embodiment has excellent moisture resistance. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view of a solid electrolyte battery according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0015] The present embodiment will be described in detail below with reference to the accompanying drawings. The drawings used in the following description may show characteristic portions enlarged for the sake of clarity, and the dimensional proportions of each component may differ from the actual proportions. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto. Appropriate modifications may be made within the scope of the present invention.

[0016] "Solid electrolyte" A solid electrolyte is a material that can move ions in response to an external electric field. Solid electrolytes can be used as part of the solid electrolyte layer and / or electrode components of solid electrolyte batteries.

[0017] The solid electrolyte according to this embodiment has a modified layer on its surface. The modified layer may modify at least a portion of the surface of the solid electrolyte. Hereinafter, the portion of the solid electrolyte on which the modified layer is formed, which forms the main body of the solid electrolyte, will be referred to as the "matrix."

[0018] The solid electrolyte may be in the form of a powder (particles) or a sintered body obtained by sintering the powder. The solid electrolyte may also be a compact formed by compressing the powder, a compact formed by molding a mixture of the powder and a binder, or a coating formed by applying a coating containing the powder, a binder, and a solvent and then heating to remove the solvent. The main structure of the solid electrolyte may be amorphous or crystalline. The main structure of the solid electrolyte may be a triclinic, monoclinic, orthorhombic (orthorhombic), tetragonal, hexagonal, or cubic crystal system, or may be partially or entirely amorphous. The main structure of the solid electrolyte may also be a core-shell structure, in which the core is crystalline and the shell is amorphous, or conversely, the core may be amorphous and the shell may be crystalline.

[0019] The matrix contains lithium, a metal element, and a halogen. The metal element is any one selected from the group consisting of Mg, Al, Sc, Y, Nb, Zr, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, In, Sn, Ta, W, and lanthanides. The matrix is, for example, A a E b G c X d ...includes a compound represented by (1).

[0020] In formula (1), A is at least one element selected from the group consisting of Li, Cs, Ca, Rb, Sr, and Ba; E is at least one element selected from the group consisting of Mg, Al, Sc, Y, Nb, Zr, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, In, Sn, Ta, W, and lanthanoids; and G is O, OH, BO2, BO3, BO4, BO6, BO7, CO3, NO3, AlO2, SiO3, SiO4, SiO7, SiO9, SiO 11 , SiO 18 , PO3, PO4, P2O7, P3O 10, SO3, SO4, SO5, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, BF4, PF6, B((COO)2), (COO)2, N, AlCl4, CF3SO3, CH3COO, CF3COO, OOC-(CH2)2-COO, OOC-CH2-COO, OOC-CH(OH)-CH(OH)-COO, OOC-CH(OH)-CH2-COO, C6H5SO3, OOC-CH=CH-COO (maleate), OOC-CH=CH-COO (fumarate), C(OH)(CH2COOH)2COO, AsO4, BiO4, CrO4, MnO4, PtF6, PtCl6, PtBr6, PtI6, SbO4, SeO4, TeO4, HCOO, SCN, NH2, CH3O, CH3CH2O, O-(CH2)-O (ethylene glycolate), O-CH2-CH(OH)-CH2-O (glycerolate), OOCCH2COO (malonate), ethylenediamine tetraacetate, citrate, nitrilotriacetate, penicillamineate, dimercapto-oleate, cyclopentadienyl, and at least one group selected from the group consisting thereof, X is at least one element selected from the group consisting of F, Cl, Br, and I, a satisfies 0.5 ≦ a < 6, b satisfies 0 < b < 2, c satisfies 0 ≦ c ≦ 6.0, and d satisfies 0 < d ≦ 6.1.

[0021] In formula (1), A contains only Li or a part of Li is substituted with Cs, Ca, Rb, Sr, or Ba. When a part of Li is substituted with Ca, Rb, Sr, Cs, or Ba, the reduction resistance of the solid electrolyte is improved.

[0022] For example, when A contains Li and Ba, the ratio of Li to Ba is preferably 0.001 or more and 0.06 or less, more preferably 0.015 or more and 0.036 or less, in terms of molar ratio (Ba / (Li + Ba)). Also, for example, when A contains Li and Cs, the ratio of Li to Cs is preferably 0.005 or more and 0.1 or less, more preferably 0.01 or more and 0.04 or less, in terms of molar ratio (Cs / (Li + Cs)). When the solid electrolyte satisfies these relationships, the reduction resistance of the solid electrolyte is improved.

[0023] In formula (1), a satisfies 0.5 ≤ a < 6, preferably satisfies 2.0 ≤ a ≤ 4.0, and more preferably satisfies 2.5 ≤ a ≤ 3.5. In the compound represented by formula (1), if a is 0.5 ≤ a < 6, the content of Li contained in the compound becomes appropriate and the ionic conductivity of the solid electrolyte increases.

[0024] In formula (1), E is at least one element selected from the group consisting of Mg, Al, Sc, Y, Nb, Zr, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, In, Sn, Ta, W, and lanthanoids. E is an element that forms the skeleton of the halide-based solid electrolyte represented by formula (1). The lanthanoids are La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. The solid electrolyte containing E has a wide potential window and high ionic conductivity. It is more preferable that E is any one of Al, Sc, Y, Zr, and La, further preferably Y or Zr, and particularly preferably contains Zr.

[0025] In formula (1), b is 0 < b < 2. Since the effect of containing E can be obtained more effectively, it is preferable that b ≥ 0.6. Also, when b ≤ 1, the density of the solid electrolyte decreases and it becomes easier to secure a path for ions to conduct.

[0026] In formula (1), G is O, OH, BO2, BO3, BO4, B3O6, B4O7, CO3, NO3, AlO2, SiO3, SiO4, Si2O7, Si3O9, Si4O 11 , Si6O 18 , PO3, PO4, P2O7, P3O 10, SO3, SO4, SO5, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, BF4, PF6, B((COO)2), (COO)2, N, AlCl4, CF3SO3, CH3COO, CF3COO, OOC-(CH2)2-COO, OOC-CH2-COO, OOC-CH(OH)-CH(OH)-COO, OOC-CH(OH)-CH2-COO, C6H5SO3, OOC-CH=CH-COO (maleate), OOC-CH=CH-COO (fumarate), C(OH)(CH2COOH)2COO , AsO4, BiO4, CrO4, MnO4, PtF6, PtCl6, PtBr6, PtI6, SbO4, SeO4, TeO4, HCOO, SCN, NH2, CHO, CHCHO, CHCHO, O-(CH2)-O (ethylene glycolate), O-CH2-CH(OH)-CH2-O (glycerate), OOCCH2COO (malonate), ethylenediaminetetraacetate, citrate, nitrilotriacetate, penicillamate, dimercaptoate, and cyclopentadienyl.

[0027] B((COO)2) is bisoxalatoborate, OOC-(CH2)2-COO is succinate, OOC-CH2-COO is malonate, OOC-CH(OH)-CH(OH)-COO is tartrate, OOC-CH(OH)-CH2-COO is malate, C6H5SO3 is benzenesulfonate, OOC-CH=CH-COO is maleate, OOC-CH=CH-COO is fumarate, and C(OH)(CH2COOH)2COO is citrate. Maleic acid is the trans isomer, and fumaric acid is the cis isomer; they have the same chemical formula, but are geometric isomers.

[0028] G is preferably, for example, O, OH, CO3, (COO)2, O—(CH2)—O, or SO4, and particularly preferably O. O has a strong covalent bond with E, making E less likely to be reduced.

[0029] In the compound represented by formula (1), c satisfies 0 ≦ c ≦ 6.0, preferably 0.1 ≦ c, and more preferably 0.5 ≦ c. In this range, the solid electrolyte containing G has a wide potential window on the reduction side and is less likely to be reductively decomposed. Also, it is preferable that c ≦ 3.0. When the content of G is large, the ionic conductivity of the solid electrolyte decreases.

[0030] In formula (1), X is at least one selected from the group consisting of F, Cl, Br, and I. When the solid electrolyte contains X, the ionic conductivity of the solid electrolyte increases. It is particularly preferable that X contains Cl. When X is Cl, it becomes a solid electrolyte with high ionic conductivity and a good balance of oxidation resistance and reduction resistance.

[0031] In the compound represented by formula (1), 0 < d ≦ 6.1. In the compound represented by formula (1), it is preferable that d ≧ 1. When d ≧ 1, when the solid electrolyte is pressure-molded into a pellet shape, a pellet having sufficient strength can be obtained. Also, when d ≧ 1, the effect of increasing the ionic conductivity by containing X can be sufficiently obtained.

[0032] The halide-based solid electrolyte represented by formula (1) is, for example, Li2ZrCl6, Li2ZrOCl4, Li2ZrN 0.1 Cl 5.7 , Li2Zr(OH) 1.5 Cl 4.5 , Li2ZrCO3Cl4, Li2ZrSO4Cl4, Li2ZrPO3Cl4, Li2ZrCH3OCl5, Li2ZrNH2Cl5, Li2Zr(HCOO) 0.5 Cl 5.5 , Li2Zr(CH3COO) 0.2 Cl 5.8 , Li2Zr(CF3COO) 0.2 Cl 5.8 , Li2Zr((COO)2) 0.1 Cl 5.8 , Li2Zr(EG) 0.1 Cl 5.7 (EG is ethylene glycol anion, that is - O-(CH2)2-O -), Li2Zr bis(cyclopentadienyl)Cl4, Li3YCl6, Li3YOCl4, Li3YSO4Cl4, Li3YCO3Cl4, LiNbOCl4, LiTaOCl4, etc.

[0033] The modified layer includes an oxide containing a metal element and a halogen. α X β The compound may contain a compound represented by the formula: M is the metal element described above and is at least one element selected from the group consisting of Mg, Al, Sc, Y, Nb, Zr, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, In, Sn, Ta, W, and lanthanides. X is a halogen and is at least one element selected from the group consisting of F, Cl, Br, and I. α satisfies 0<α≦3, and β satisfies 0<β≦6.

[0034] The modified layer may have the above compound where β=0. In this case, the modified layer is made of MO α The metal oxide is expressed as follows:

[0035] The modified layer may contain sulfur in addition to the metal element and halogen. α S γ X β The compound may include a compound represented by the formula: where γ satisfies 0≦γ≦2.

[0036] The thickness of the modified layer is, for example, 1 nm to 1000 nm, preferably 5 nm to 900 nm, and more preferably 10 nm to 800 nm. The thickness of the modified layer can be measured from a cross-sectional image taken using a transmission electron microscope. The thickness of the modified layer is calculated as the average value of the thicknesses measured at any five points.

[0037] (Method of manufacturing solid electrolyte) When the solid electrolyte is in a powder state, it can be produced by, for example, a mechanochemical method. For example, raw material powders containing predetermined elements in a predetermined molar ratio are mixed and reacted. When the solid electrolyte is in a sintered state, it can be produced by, for example, a solid-state reaction method. For example, raw material powders containing predetermined elements in a predetermined molar ratio are mixed and molded, and then sintered in a vacuum or inert gas atmosphere.

[0038] When a halide raw material is contained in the raw powder, the halide raw material is likely to evaporate when the temperature is increased. Therefore, halogen gas may be present in the sintering atmosphere to compensate for the halogen. Furthermore, when a halide raw material is contained in the raw powder, sintering may be performed by hot pressing using a mold with high airtightness. In this case, the mold has high airtightness, so evaporation of the halide raw material due to sintering can be suppressed. By sintering in this manner, a solid electrolyte in the form of a sintered body made of a compound having a predetermined composition is obtained.

[0039] A modified layer is formed on the surface of the solid electrolyte matrix prepared by the above procedure. The modified layer can be formed by oxygen-treating the solid electrolyte matrix. The oxygen treatment is a process in which the matrix is ​​exposed to an oxygen-containing environment. The oxygen treatment is carried out in a dry environment that does not contain moisture. For example, the treatment is carried out in an atmosphere of dry air, oxygen gas, or an inert gas containing oxygen gas.

[0040] The modified layer can also be formed by subjecting the solid electrolyte substrate to a moisture treatment. The moisture treatment involves exposing the substrate to an environment containing moisture (water vapor). The moisture treatment is carried out in an atmosphere of water vapor or an inert gas containing water vapor.

[0041] The solid electrolyte according to this embodiment has excellent moisture resistance. This is thought to be because the modified layer prevents moisture from entering the base. The solid electrolyte according to this embodiment is resistant to degradation by water, and its ionic conductivity is less likely to decrease even in the atmosphere. Therefore, by using the solid electrolyte according to this embodiment, a solid electrolyte battery can be fabricated not only in a glove box filled with an inert gas, but also in a dry room where the moisture content is below a certain level.

[0042] [Solid electrolyte battery] Fig. 1 is a cross-sectional schematic diagram of a solid electrolyte battery according to this embodiment. The solid electrolyte battery 10 shown in Fig. 1 includes a positive electrode 1, a negative electrode 2, and a solid electrolyte layer 3. The solid electrolyte layer 3 is sandwiched between the positive electrode 1 and the negative electrode 2. The above-mentioned solid electrolyte may be contained in the solid electrolyte layer 3, or in the positive electrode 1 or the negative electrode 2, or in both. External terminals (not shown) are connected to the positive electrode 1 and the negative electrode 2, and are electrically connected to the outside.

[0043] The solid electrolyte battery 10 is charged or discharged by the exchange of ions between the positive electrode 1 and the negative electrode 2 via the solid electrolyte layer 3, and the exchange of electrons via an external circuit. The solid electrolyte battery 10 may be a laminate in which the positive electrode 1, the negative electrode 2, and the solid electrolyte layer 3 are stacked, or may be a wound body in which the laminate is wound. Solid electrolyte batteries are used, for example, in laminate batteries, prismatic batteries, cylindrical batteries, coin batteries, button batteries, etc.

[0044] <Solid electrolyte layer> The solid electrolyte layer 3 is sandwiched between the positive electrode 1 and the negative electrode 2. The solid electrolyte layer 3 includes a solid electrolyte that can transfer ions when an external voltage is applied. For example, the solid electrolyte conducts lithium ions and inhibits the transfer of electrons.

[0045] The solid electrolyte layer 3 is, for example, a halide-based solid electrolyte. The solid electrolyte layer 3 includes, for example, the above-mentioned solid electrolyte. When the above-mentioned solid electrolyte is contained in the positive electrode 1 or the negative electrode 2, the solid electrolyte contained in the solid electrolyte layer 3 is not limited to the above-mentioned solid electrolyte.

[0046] <Positive electrode> 1, the positive electrode 1 has a plate-like (foil-like) positive electrode current collector 1A and a positive electrode mixture layer 1B. The positive electrode mixture layer 1B is in contact with at least one surface of the positive electrode current collector 1A.

[0047] "Positive electrode current collector" The positive electrode current collector 1A may be made of any electrically conductive material that is resistant to oxidation during charging and corrosion. The positive electrode current collector 1A may be made of a metal such as aluminum, stainless steel, nickel, or titanium, or a conductive resin. The positive electrode current collector 1A may be in the form of a powder, foil, punched, or expanded.

[0048] "Positive electrode mixture layer" The positive electrode mixture layer 1B contains a positive electrode active material, and optionally a solid electrolyte, a binder, and a conductive additive.

[0049] (Cathode active material) The positive electrode active material is not particularly limited as long as it can reversibly absorb and release, and insert and extract (intercalate and deintercalate) lithium ions. Positive electrode active materials used in known lithium ion secondary batteries can be used. Examples of positive electrode active materials include lithium-containing metal oxides and lithium-containing metal phosphates.

[0050] Lithium-containing metal oxides include, for example, lithium cobalt oxide (LiCoO), lithium nickel oxide (LiNiO), lithium manganese spinel (LiMnO), and lithium manganese oxides represented by the general formula: LiNi x Co y Mn z O2 (x+y+z=1), lithium vanadium compounds (LiVOPO4, Li3V2(PO4)3), olivine-type LiMPO4 (where M represents at least one element selected from Co, Ni, Mn, and Fe), and lithium titanate (Li4Ti5O 12 ) etc.

[0051] The positive electrode active material may also be lithium-free. Examples of such positive electrode active materials include non-lithium-containing metal oxides (MnO2, V2O5, etc.), non-lithium-containing metal sulfides (MoS2, etc.), and non-lithium-containing fluorides (FeF3, VF3, etc.). When using a lithium-free positive electrode active material, the negative electrode is doped with lithium ions in advance, or a lithium-ion-containing negative electrode is used.

[0052] (binder) The positive electrode mixture layer 1B may contain a binder. The binder bonds together the positive electrode active material, solid electrolyte, and conductive additive that constitute the positive electrode mixture layer 1B. The binder also bonds the positive electrode mixture layer 1B and the positive electrode current collector 1A. The binder preferably has oxidation resistance and good adhesiveness.

[0053] Examples of binders used in the positive electrode mixture layer 1B include polyvinylidene fluoride (PVDF) or copolymers thereof, polytetrafluoroethylene (PTFE), polyamide (PA), polyimide (PI), polyamideimide (PAI), polybenzimidazole (PBI), polyethersulfone (PES), polyacrylic acid (PA) and copolymers thereof, metal ion crosslinked polyacrylic acid (PA) and copolymers thereof, maleic anhydride-grafted polypropylene (PP), maleic anhydride-grafted polyethylene (PE), or mixtures thereof. Among these, PVDF is particularly preferred as the binder.

[0054] The binder content in the positive electrode mixture layer 1B is not particularly limited, but is preferably 1% by mass to 15% by mass, and more preferably 3% by mass to 5% by mass, based on the total mass of the positive electrode active material, solid electrolyte, conductive additive, and binder. If the binder content is too low, it tends to be difficult to form a positive electrode 1 with sufficient adhesive strength. Conversely, if the binder content is too high, general binders are electrochemically inactive and do not contribute to discharge capacity, making it difficult to obtain sufficient volume or mass energy density.

[0055] (solid electrolyte) The positive electrode mixture layer 1B may contain a solid electrolyte. The solid electrolyte is, for example, the solid electrolyte described above. The solid electrolyte may be a solid electrolyte other than the solid electrolyte described above. The content of the solid electrolyte in the positive electrode mixture layer 1B is not particularly limited, but is preferably 1% by volume or more and 50% by volume or less, and more preferably 5% by volume or more and 30% by volume or less, based on the total mass of the positive electrode active material, the solid electrolyte, the conductive additive, and the binder.

[0056] (Conductive additive) The conductive additive improves the electronic conductivity of the positive electrode mixture layer 1B. Known conductive additives can be used. Examples of conductive additives include carbon materials such as carbon black, graphite, graphitized carbon black, carbon nanotubes, and graphene; metals such as aluminum, copper, nickel, stainless steel, iron, and amorphous metals; conductive oxides such as ITO; conductive polymers (polyaniline, polyacetylene, and the like); and mixtures thereof. The conductive additive may be in the form of powder or fiber.

[0057] There are no particular limitations on the content of the conductive additive in the positive electrode mixture layer 1B. When the positive electrode mixture layer 1B contains the conductive additive, the content is preferably 0.5% by mass or more and 20% by mass or less, and more preferably 1% by mass or more and 5% by mass or less, based on the total mass of the positive electrode active material, the solid electrolyte, the conductive additive, and the binder.

[0058] <Negative electrode> 1, the negative electrode 2 has a negative electrode current collector 2A and a negative electrode mixture layer 2B. The negative electrode mixture layer 2B is in contact with at least one surface of the negative electrode current collector 2A.

[0059] "Negative electrode current collector" The negative electrode current collector 2A only needs to be electrically conductive. Examples of materials that can be used as the negative electrode current collector 2A include metals such as copper, aluminum, nickel, stainless steel, and iron, and conductive resin foil. The negative electrode current collector 2A may be in the form of powder, foil, punched, or expanded.

[0060] "Negative electrode mixture layer" The negative electrode mixture layer 2B contains a negative electrode active material, and optionally a solid electrolyte, a binder, and a conductive additive.

[0061] (Negative electrode active material) The negative electrode active material is not particularly limited as long as it can reversibly absorb and release lithium ions and insert and extract lithium ions. As the negative electrode active material, any negative electrode active material used in known solid electrolyte batteries can be used.

[0062] Examples of the negative electrode active material include carbon materials such as natural graphite, artificial graphite, mesocarbon microbeads, mesocarbon fiber (MCF), cokes, glassy carbon, and organic compound sintered bodies, Si, SiO x Metals that can combine with lithium, such as Sn and aluminum, their alloys, composites of these metals and carbon materials, lithium titanate (Li4Ti5O 12 ), oxides such as SnO2, metallic lithium, etc. The negative electrode active material is preferably natural graphite.

[0063] (binder) The negative electrode mixture layer 2B may contain a binder. The binder bonds together the negative electrode active material, solid electrolyte, and conductive additive that constitute the negative electrode mixture layer 2B. The binder also bonds the negative electrode mixture layer 2B and the negative electrode current collector 2A.

[0064] Examples of binders used in the negative electrode mixture layer 2B include polyvinylidene fluoride (PVDF) or copolymers thereof, polytetrafluoroethylene (PTFE), polyamide (PA), polyimide (PI), polyamideimide (PAI), polybenzimidazole (PBI), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid (PA) and copolymers thereof, metal ion crosslinked polyacrylic acid (PA) and copolymers thereof, maleic anhydride-grafted polypropylene (PP), maleic anhydride-grafted polyethylene (PE), and mixtures thereof. Among these, it is preferable to use one or more binders selected from SBR, CMC, and PVDF.

[0065] The binder content in the negative electrode mixture layer 2B is not particularly limited, but is preferably 1% by mass or more and 15% by mass or less, and more preferably 1.5% by mass or more and 10% by mass or less, based on the total mass of the negative electrode active material, the conductive additive, and the binder.

[0066] (solid electrolyte) The negative electrode mixture layer 2B may contain a solid electrolyte. The solid electrolyte may be, for example, the solid electrolyte described above. The solid electrolyte may be a solid electrolyte other than the solid electrolyte described above. The content of the solid electrolyte is not particularly limited, but is preferably 1% by volume or more and 50% by volume or less, and more preferably 5% by volume or more and 30% by volume or less, based on the total mass of the negative electrode active material, solid electrolyte, conductive additive, and binder.

[0067] (Conductive additive) The conductive additive contained in the negative electrode mixture layer 2B can be the same as that in the positive electrode mixture layer 1B. The content of the conductive additive in the negative electrode mixture layer 2B is preferably 0.5% by mass or more and 20% by mass or less, and more preferably 1% by mass or more and 12% by mass or less, relative to the negative electrode active material.

[0068] <Exterior body> The exterior housing houses a battery element consisting of a positive electrode 1, a solid electrolyte layer 3, and a negative electrode 2. The exterior housing prevents moisture and other elements from entering the interior from the outside. The exterior housing is, for example, a metal laminate film made by coating both sides of a metal foil with a polymer film. The metal laminate film is formed into a bag shape and the opening is heat-sealed to form the exterior housing.

[0069] The metal foil is, for example, aluminum foil, stainless steel foil, etc. The polymer film disposed on the outside of the exterior body is preferably made of a polymer with a high melting point, such as polyethylene terephthalate (PET), polyamide, etc. The polymer film disposed on the inside of the exterior body is, for example, polyethylene (PE), polypropylene (PP), etc.

[0070] <External terminal> The external terminals include a positive electrode terminal and a negative electrode terminal. The positive electrode terminal is electrically connected to the positive electrode 1, and the negative electrode terminal is electrically connected to the negative electrode 2. The external terminals are made of a conductive material such as aluminum or nickel.

[0071] [Solid electrolyte battery manufacturing method] Next, a method for manufacturing a solid electrolyte battery according to this embodiment will be described. First, the solid electrolyte according to this embodiment is manufactured by the method described above.

[0072] Next, the positive electrode 1 is prepared. The positive electrode 1 is produced by applying a paste containing a positive electrode active material onto a positive electrode current collector 1A and drying it to form a positive electrode mixture layer 1B. The above-mentioned solid electrolyte may be added to the paste containing the positive electrode active material.

[0073] Next, the negative electrode 2 is prepared. The negative electrode 2 is produced by applying a paste containing a negative electrode active material onto a negative electrode current collector 2A and drying it to form a negative electrode mixture layer 2B. The above-mentioned solid electrolyte may be added to the paste containing the negative electrode active material.

[0074] The battery element can be produced, for example, by powder molding. A guide with a hole is placed on the positive electrode 1, and the guide is filled with a solid electrolyte. The solid electrolyte used here is, for example, the solid electrolyte described above. The surface of the solid electrolyte is then smoothed, and the negative electrode 2 is placed on top of the solid electrolyte. This sandwiches the solid electrolyte between the positive electrode 1 and the negative electrode 2. Pressure is then applied to the positive electrode 1 and the negative electrode 2 to pressure-mold the solid electrolyte. This pressure molding produces a laminate in which the positive electrode 1, solid electrolyte layer 3, and negative electrode 2 are stacked in this order.

[0075] Next, external terminals are welded to the positive electrode current collector 1A of the positive electrode 1 and the negative electrode current collector 2A of the negative electrode 2, which form the laminate, by a known method, to electrically connect the positive electrode current collector 1A or the negative electrode current collector 2A to the external terminals. Thereafter, the laminate connected to the external terminals is housed in an exterior body, and the opening of the exterior body is heat-sealed to seal it. Through these steps, the solid electrolyte battery of this embodiment is obtained.

[0076] The solid electrolyte battery according to this embodiment includes a solid electrolyte having a predetermined composition, and therefore the ionic conductivity of the solid electrolyte is unlikely to decrease even in a moisture-containing atmosphere, resulting in excellent ionic conductivity.

[0077] The above describes the embodiments of the present invention in detail with reference to the drawings. However, each configuration and combination thereof in each embodiment is an example, and additions, omissions, substitutions, and other modifications of the configurations are possible within the scope that does not deviate from the spirit of the present invention. [Example]

[0078] "Example 1" (Preparation of solid electrolyte) In a glove box with a dew point of approximately -85°C, lithium sulfate (Li2SO4) and zirconium chloride (ZrCl4) were weighed out in a 1:1 molar ratio and placed in a zirconia sealed container for a planetary ball mill, which had already contained zirconia balls. The sealed container was then covered with a lid, screwed onto the container body, and sealed between the lid and the container with polyimide tape. The polyimide tape effectively blocks moisture. The zirconia sealed container was then placed in the planetary ball mill. The raw material powders were subjected to a mechanochemical reaction for 24 hours at a rotation speed of 500 rpm and a revolution speed of 500 rpm (rotation and revolution directions opposite). This reaction yielded the solid electrolyte Li2ZrSO4Cl4.

[0079] The planetary ball mill is installed in a normal atmosphere (air). The zirconia sealed container for the planetary ball mill is screwed in and sealed with polyimide tape, and when the zirconia sealed container is set in the planetary ball mill, it is firmly pressed and fixed in place. Therefore, even in a normal atmosphere, it is thought that almost no moisture from the air gets mixed into the zirconia sealed container.

[0080] The zirconia sealed container was then brought into a glove box filled with oxygen gas at 1 atmosphere, the lid was opened, and the container was exposed to oxygen for 30 minutes. The solid electrolyte was stirred with a spatula every 5 minutes to ensure that oxygen was distributed around the solid electrolyte. The container was then covered with a lid, screwed onto the container body, and the space between the lid and the container was sealed with polyimide tape. The zirconia sealed container was then placed in a planetary ball mill. The solid electrolyte powder was subjected to a mechanochemical reaction for 1 hour at a rotation speed of 500 rpm and a revolution speed of 500 rpm (the rotation direction and the revolution direction were opposite), resulting in oxygen treatment of the solid electrolyte. It is believed that the solid electrolyte surface reacted with oxygen gas as shown in the following formula (2), producing zirconium oxyhalide. TEM-EDX composition analysis of the solid electrolyte after oxygen treatment revealed ZrO on the surface. α Cl βIt was confirmed that a modified layer containing zirconium oxyhalide represented by the formula (1) was formed. The thickness of the modified layer containing zirconium oxyhalide was 11 nm. Li2ZrSO4Cl4+O2→ZrO α Cl β +xLiCl+yLi2SO4(2)

[0081] [Measurement of ionic conductivity] The solid electrolyte after the oxygen treatment was brought into a dry room, and 0.2 g of the solid electrolyte was weighed onto aluminum foil. The dry room environment was air at a dew point of -50°C (relative humidity 2000 ppm) and a room temperature of 25°C (oxygen concentration approximately 21% by volume, oxygen partial pressure 0.21 atm). The weighed solid electrolyte was exposed to the dry room for 4 hours and 8 hours. Next, in a glove box with a dew point of approximately -85°C and circulating argon gas, the solid electrolyte powder exposed for the predetermined time in the dry room was filled into a pressure molding die and pressure molded under a load of approximately 30 kN to prepare a measurement cell for ionic conductivity.

[0082] The pressure molding die consists of a 10 mm diameter cylinder made of PEEK (polyether ether ketone), and upper and lower punches made of SKD11 material with a diameter of 9.99 mm.

[0083] Next, a 50 mm diameter, 5 mm thick stainless steel disk and a Teflon® disk with four screw holes were prepared and set into the pressure molding die as follows: stainless steel disk / Teflon® disk / pressure molding die / Teflon® disk / stainless steel disk, and the four screws were tightened with a torque of approximately 3 N m. Screws were also inserted into the screw holes on the sides of the upper and lower punches to serve as external connection terminals.

[0084] The external connection terminal was connected to a Bio-Logic EC-Lab electrochemical measurement system VMP-300, and ionic conductivity was measured using the impedance measurement method at a measurement frequency range of 1 MHz to 0.1 Hz, an amplitude of 10 mV, and a temperature of 25°C.

[0085] "Example 2" Example 2 differs from Example 1 in that the conditions for the oxygen treatment were changed. In Example 2, the solid electrolyte was exposed to the same dry room as in Example 1 (dew point -50°C (relative humidity 2000 ppm), air at room temperature of 25°C (oxygen concentration approximately 21% by volume)) for 5 minutes. Three minutes after the start of exposure, the solid electrolyte was stirred with a spatula to ensure that oxygen was distributed around the solid electrolyte. Next, a mechanochemical reaction was carried out for 1 hour as in Example 1. Composition analysis of the solid electrolyte after the oxygen treatment using TEM-EDX revealed that ZrO α Cl β It was confirmed that a modified layer containing zirconium oxyhalide represented by the formula (1) was formed. The thickness of the modified layer containing zirconium oxyhalide was 5 nm. As in Example 1, the sample was exposed to the dry room for 2 hours, 4 hours, and 8 hours, and the change in ionic conductivity over time was measured.

[0086] "Example 3" In Example 3, the oxygen-treated solid electrolyte of Example 1 was heat-treated. The heat treatment was carried out in an electric furnace in an argon glove box (dew point -85°C, relative humidity 20 ppm, 25°C). The temperature was increased to 130°C at a rate of 2°C / min and maintained at 130°C for 6 hours. Then, the solid electrolyte was naturally cooled. The thickness of the modified layer containing zirconium oxyhalide in Example 3 was 9 nm. The other conditions were the same as in Example 1, and the change in ionic conductivity over time was measured.

[0087] Example 4 In Example 4, a solid electrolyte synthesized in the same manner as in Example 1 was treated with a trace amount of water vapor. The zirconia sealed container in which the solid electrolyte was synthesized by mechanochemical reaction was brought into a glove box (dew point -85°C, relative humidity 20 ppm, 25°C), the lid was opened, and the container was exposed to a trace amount of water vapor for 30 minutes. The solid electrolyte was stirred with a spatula every 5 minutes to ensure that the water vapor was distributed around the solid electrolyte. The sealed container was then covered with a lid, screwed onto the container body, and the space between the lid and the container was sealed with polyimide tape. The zirconia sealed container was placed in a planetary ball mill. The solid electrolyte powder was subjected to a mechanochemical reaction for 1 hour at a rotation speed of 500 rpm and a revolution speed of 500 rpm (the rotation direction and the revolution direction were opposite), and the solid electrolyte was treated with water vapor. It is believed that the solid electrolyte surface reacted with the trace amount of water as shown in formula (3), resulting in the formation of a modified layer containing zirconium oxyhalide. The thickness of the modified layer including the thickness of the zirconium oxysulfide halide film was 12 nm. The other conditions were the same as in Example 1, and the change in ionic conductivity over time was measured. Li2ZrSO4Cl4+H2O→ZrO γ S δ Cl ε +zLiCl+yHCl (3)

[0088] Examples 5 to 20 differ from Example 1 in that the matrix of the solid electrolyte forming the modified layer was changed from Li2ZrSO4Cl4 to another solid electrolyte. The raw material composition, matrix solid electrolyte, etc. are summarized in Table 1. The other conditions were the same as in Example 1, and the change over time in the ionic conductivity of the solid electrolyte layer of Examples 5 to 20 was measured. In Example 7, the atmospheric pressure during the oxygen treatment was 10 atmospheres.

[0089] "Comparative Example 1" Comparative Examples 1 and 2 differ from Examples 1 and 2, respectively, in that no oxygen treatment was performed. The other conditions were the same as in Example 1, and the change in ionic conductivity over time was measured.

[0090] The measurement results of the ionic conductivity of Examples 1 to 20 and Comparative Examples 1 and 2 are summarized in Tables 1 and 2.

[0091] [Table 1]

[0092] [Table 2]

[0093] As shown in Tables 1 and 2, the solid electrolytes of Examples 1 to 20 on which the modified layers were formed showed a smaller decrease in ionic conductivity than the solid electrolytes of Comparative Examples 1 and 2. [Explanation of symbols]

[0094] 1... positive electrode, 1A... positive electrode current collector, 1B... positive electrode mixture layer, 2... negative electrode, 2A... negative electrode current collector, 2B... negative electrode mixture layer, 3... solid electrolyte layer, 10... solid electrolyte battery

Claims

1. a matrix containing lithium, a metal element, and a halogen; a modified layer formed on the surface of the base body, the matrix contains lithium, a metal element, and a halogen; the metal element is any one selected from the group consisting of Mg, Al, Sc, Y, Nb, Zr, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, In, Sn, Ta, W, and lanthanoids; The modified layer has an oxide containing the metal element and the halogen.

2. The solid electrolyte according to claim 1 , wherein the matrix is ​​represented by the following formula (1): A ａ E ｂ G ｃ X ｄ ・・・(1) In formula (1), A is at least one element selected from the group consisting of Li, Cs, Ca, Rb, Sr, and Ba; E is at least one element selected from the group consisting of Mg, Al, Sc, Y, Nb, Zr, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, In, Sn, Ta, W, and lanthanoids; and G is O, OH, BO ２ , B.O. ３ , B.O. ４ , B ３ O ６ , B ４ O ７ , CO ３ , NO ３ , AlO ２ , SiO ３ , SiO ４ , Si ２ O ７ , Si ３ O ９ , Si ４ O １１ , Si ６ O １８ , P.O. ３ , P.O. ４ , P ２ O ７ , P ３ O １０ , S.O. ３ , S.O. ４ , S.O. ５ , S ２ O ３ , S ２ O ４ , S ２ O ５ , S ２ O ６ , S ２ O ７ , S ２ O ８ , B.F. ４ , P.F. ６ , B((COO) ２ ), (COO) ２ , N, AlCl ４ , C.F. ３ SO ３ , C.H. ３ COO, CF ３ COO,OOC-(CH ２ ) ２ -COO,OOC-CH ２ -COO, OOC-CH(OH)-CH(OH)-COO, OOC-CH(OH)-CH ２ -COO, C ６ H ５ SO ３ , OOC-CH=CH-COO (maleate), OOC-CH=CH-COO (fumarate), C(OH)(CH ２ COOH) ２ COO, AsO ４ , Bio ４ , CrO ４ , MnO ４ , PtF ６ , PtCl ６ , PtBr ６ , PtI ６ , SbO ４ , SeO ４ , TeO ４ , HCOO, SCN, NH ２ , C.H. ３ O, CH ３ CH ２ O, O-(CH ２ )—O(ethylene glycolate), O—CH ２ -CH(OH)-CH ２ -O (glycerate), OOCCH ２ X is at least one group selected from the group consisting of F, Cl, Br, and I; a satisfies 0.5≦a<6; b satisfies 0<b<2; c satisfies 0≦c≦6.0; and d satisfies 0<d≦6.

1.

3. The solid electrolyte according to claim 2 , wherein in formula (1), E includes Zr.

4. The solid electrolyte of claim 1 , wherein the modified layer further comprises sulfur.

5. The solid electrolyte according to claim 1 , wherein the thickness of the modified layer is 1 nm or more and 1000 nm or less.

6. a positive electrode, a negative electrode, and a solid electrolyte layer sandwiched between the positive electrode and the negative electrode; 10. A solid electrolyte battery, wherein at least one of the positive electrode, the negative electrode, and the solid electrolyte layer comprises the solid electrolyte of claim 1.

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