Solid electrolytes contain a layer

Abstract

To provide a solid electrolyte-containing layer which can prevent a short circuit caused by production of dendrite.SOLUTION: An all-solid type secondary battery 100a according to an embodiment of the present invention has, between a positive electrode 10 and a negative electrode 30, a solid electrolyte-containing layer 50a including a solid electrolyte layer 20 and a heat-resistant resin layer 28 having ion conductivity. The heat-resistant resin makes an anti-short circuit layer of the all-solid type secondary battery, which can prevent a short circuit caused by production of dendrite.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a solid electrolyte-containing layer. The invention also relates to an all-solid-state secondary battery and a method for manufacturing the same, a short-circuit prevention layer, and a method for preventing short circuits in an all-solid-state secondary battery. [Background technology]

[0002] All-solid-state rechargeable batteries are rechargeable batteries that use a solid electrolyte. Solid electrolytes are broadly classified into inorganic solid electrolytes and organic solid electrolytes, and research and development for practical use is underway for both. For an example of an all-solid-state rechargeable battery using an inorganic solid electrolyte, see Patent Document 1. For an example of an all-solid-state rechargeable battery using an organic solid electrolyte, see Patent Document 2. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-199394 [Patent Document 2] Japanese Patent Publication No. 2019-102301 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, the conventional technologies described above still had room for improvement in preventing short circuits between electrodes caused by dendrites.

[0005] One aspect of the present invention aims to provide a solid electrolyte-containing layer that can prevent short circuits caused by dendrite formation. [Means for solving the problem]

[0006] The inventors have found that the above-mentioned problems can be solved by applying a heat-resistant resin with ion conductivity to an all-solid-state secondary battery. In other words, the present invention includes the following configuration. <1> Solid electrolytes, A heat-resistant resin having ionic conductivity, A solid electrolyte-containing layer, including the above. <2> The solid electrolyte-containing layer comprises a solid electrolyte layer containing the solid electrolyte and a resin layer containing the heat-resistant resin having ion conductivity. The solid electrolyte layer and the resin layer are adjacent to each other. <1> The solid electrolyte-containing layer described above. <3> The glass transition temperature of the heat-resistant resin having ionic conductivity is 200°C or higher. <1> or <2> The solid electrolyte-containing layer described above. <4> The solid electrolyte is an inorganic solid electrolyte. <1> ~ <3> A solid electrolyte-containing layer as described in any of the following. <5> Positive electrode and, <1> ~ <4> An all-solid-state secondary battery comprising a solid electrolyte-containing layer as described in any of the above, and a negative electrode. <6> Between the positive and negative electrodes, <1> ~ <4> A method for manufacturing an all-solid-state secondary battery, comprising the step of arranging a solid electrolyte-containing layer as described in any of the above. <7> A short-circuit prevention layer for all-solid-state secondary batteries, comprising a heat-resistant resin with ion conductivity. <8> Between the positive and negative electrodes, <1> ~ <4> A method for preventing short circuits in an all-solid-state secondary battery, comprising arranging a solid electrolyte-containing layer as described in any of the above. [Effects of the Invention]

[0007] According to one aspect of the present invention, a solid electrolyte-containing layer can be provided that can prevent short circuits caused by dendrite formation. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing the configuration of an all-solid-state secondary battery according to one aspect of the present invention. [Figure 2] This is a schematic diagram showing another configuration of an all-solid-state secondary battery according to another aspect of the present invention. [Modes for carrying out the invention]

[0009] The following describes in detail some examples of embodiments of the present invention, but the present invention is not limited to these.

[0010] Unless otherwise specified in this specification, "A to B" representing a numerical range means "greater than or equal to A, and less than or equal to B."

[0011] [1. Heat-resistant resin with ionic conductivity] A solid electrolyte-containing layer according to one aspect of the present invention contains a heat-resistant resin having ion conductivity. Therefore, before describing the solid electrolyte-containing layers 50a and 50b, the heat-resistant resin having ion conductivity will be described.

[0012] In this specification, "heat-resistant resin" refers to a resin that does not soften, melt, or decompose under high-temperature conditions. Here, "high-temperature environment" refers to an environment of 150°C. The glass transition temperature of the ion-conducting heat-resistant resin is preferably 200°C or higher, more preferably 250°C or higher, and even more preferably 300°C or higher. Such a resin will not soften, melt, or decompose even when the all-solid-state secondary batteries 100a and 100b are heated and used without a cooling system.

[0013] In this specification, "having ionic conductivity" means that the ionic conductivity at 80°C is 1 × 10⁻⁶. -10 This means that the ionic conductivity is 1 × 10⁻⁶ or higher. The ionic conductivity is preferably 1 × 10⁻⁶. -9 S / cm or more, more preferably 1 × 10 -8 It is S / cm or higher. In one embodiment, the ionic conductivity is the ionic conductivity of lithium ions.

[0014] One method for measuring the ionic conductivity of heat-resistant resins with ionic conductivity is the impedance method (see below for details). The sample used for measurement can be prepared, for example, by drying a suitable substrate (such as polyethylene film) impregnated with a solution of the heat-resistant resin with ionic conductivity. 1. Inside a glove box, under a dry argon atmosphere, the sample to be measured is sandwiched between two blocking electrodes (for example, electrodes made of stainless steel) to create a coin-type lithium battery CR2032 (hereinafter sometimes referred to as a coin cell). 2. The obtained coin cells are conditioned in a constant temperature bath at 80°C for 12 hours. 3. Using an impedance measuring device, the measurement is performed at the desired temperature, in a frequency range of 0.1 Hz to 1 MHz, and with an amplitude of 10 mV. The ionic conductivity σ can be calculated using the following formula. σ(S·cm -1 ) = t(cm) × R(Ω) / A(cm 2 ) In the formula, R represents the impedance value, A represents the sample area, and t represents the sample thickness.

[0015] It should be noted that, as used herein, "heat-resistant resin having ionic conductivity" is different from "a mixture of a heat-resistant resin that does not have ionic conductivity and an ionic conductive substance." In heat-resistant resins having ionic conductivity, the heat-resistant resin molecules themselves possess ionic conductivity.

[0016] A heat-resistant resin that does not possess ionic conductivity can be made ionically conductive by introducing appropriate functional groups. In one embodiment, the ionically conductive heat-resistant resin is a heat-resistant resin containing functional groups having anions, wherein at least some atoms of the main chain of the heat-resistant resin are substituted with functional groups having anions. The ionically conductive heat-resistant resin may have functional groups having two or more types of anions.

[0017] An example of a functional group containing anions is the sulfonate group (-SO3 -), carboxylate group (-COO - ), phosphonate group (-PO3 - ), trifluoroborate group (-BF3 - ), etc. These functional groups may have an alkyl chain of about C1 to C20. That is, examples of the functional group having an anion include an alkyl sulfonate group (-C n H 2n SO3 - ), an alkyl carboxylate group (-C n H 2n COO - ), an alkyl phosphonate group (-C n H 2n PO3 - ), an alkyl trifluoroborate group (-C n H 2n BF3 - group) (in each formula, n is an integer of 1 to 20). The functional group having an anion may be at the end of the alkyl chain or in the chain.

[0018] The amount of the functional group having an anion contained in the heat-resistant resin having ionic conductivity is preferably 1 to 99 mol%, more preferably 10 to 80 mol%, based on 100 mol% of the total amount of atoms that can be substituted by the functional group in the heat-resistant resin.

[0019] For example, in the case of a resin in which polyamide is substituted with the functional group, the amount of the functional group having an anion is preferably 1 to 99 mol%, more preferably 10 to 80 mol%, based on 100 mol% of the total amount of hydrogen atoms in the amide groups of the polyamide.

[0020] Further, the heat-resistant resin having ionic conductivity has an alkylene oxide structure (-(C x H 2x O) Y- (wherein the formula, X is an integer of about 1 to 20, and Y is an integer of about 1 to 20) may be present. The heat-resistant resin having ionic conductivity may contain alkylene oxide structures as a main chain or as side chains. However, if the proportion of alkylene oxide structures in the heat-resistant resin having ionic conductivity is large, the glass transition temperature of the resin may decrease, and the heat resistance may decrease. For this reason, the amount of alkylene oxide structures contained in the heat-resistant resin having ionic conductivity is preferably 10 mol% to 80 mol%, with the total amount of atoms that can be substituted by alkylene oxide structures in the heat-resistant resin being 100 mol%.

[0021] Examples of the heat-resistant resins mentioned above include polyamide, polyimide, polyamide-imide, polycarbonate, polyacetal, polysulfone, polyphenylene sulfide, polyetheretherketone, aromatic polyester, polyethersulfone, polyetherimide, cellulose ethers, polybenzimidazole, polyurethane, and melamine resin. These heat-resistant resins may be used individually or in combination of two or more types.

[0022] From the viewpoint of having higher heat resistance, polyamides, polyimides, polyamideimides, aromatic polyesters, polyethersulfones, and polyetherimides are preferred as the heat-resistant resin, and polyamides, polyimides, and polyamideimides are more preferred. Among polyamides, polyimides, and polyamideimides, nitrogen-containing aromatic polymers are even more preferred from the viewpoint of heat resistance. Examples of nitrogen-containing aromatic polymers include aromatic polyamides (para-oriented aromatic polyamides, meta-oriented aromatic polyamides, etc.), aromatic polyimides, and aromatic polyamideimides, among which aromatic polyamides are even more preferred, and para-oriented aromatic polyamides are particularly preferred. In this specification, aromatic polyamides may be expressed as "aramids," and para-oriented aromatic polyamides as "para-aramids."

[0023] Para-aramid is a heat-resistant resin obtained by the condensation polymerization of a para-oriented aromatic diamine and a para-oriented aromatic dicarboxylic acid halide. The repeating units that substantially constitute para-aramid have amide bonds at the para position of the aromatic ring. Alternatively, the repeating units have amide bonds at orientation positions corresponding to the para position of the aromatic ring. Note that having amide bonds at orientation positions corresponding to the para position of the aromatic ring means having two amide bonds at an angle of 180 degrees from the aromatic ring.

[0024] Specific examples of para-aramids include poly(paraphenylene terephthalamide), poly(parabenzamide), poly(4,4'-benzanilide terephthalamide), poly(paraphenylene-4,4'-biphenylenedicarboxylic acid amide), poly(paraphenylene-2,6-naphthalenedicarboxylic acid amide), poly(2-chloro-paraphenylene terephthalamide), and paraphenylene terephthalamide / 2,6-dichloroparaphenylene terephthalamide copolymers.

[0025] Examples of aromatic polyimides include all aromatic polyimides produced by condensation polymerization of aromatic acid dianhydrides and aromatic diamines. Examples of acid dianhydrides include pyromellitic acid dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic acid dianhydride, 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane, and 3,3',4,4'-biphenyltetracarboxylic acid dianhydride. Examples of diamines include oxydianiline, paraphenylenediamine, benzophenonediamine, 3,3'-methylenedianiline, 3,3'-diaminobensophenone, 3,3'-diaminodiphenylsulfone, and 1,5'-naphthalenediamine.

[0026] Examples of aromatic polyamide-imides include resins obtained from the condensation polymerization of aromatic dicarboxylic acids and aromatic diisocyanates, and resins obtained from the condensation polymerization of aromatic dianhydrides and aromatic diisocyanates. Examples of aromatic dicarboxylic acids include isophthalic acid and terephthalic acid. An example of an aromatic dianhydride is trimellitic anhydride. Examples of aromatic diisocyanates include 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, orthotrilane diisocyanate, and m-xylene diisocyanate.

[0027] Among the heat-resistant resins exemplified above, examples of resins with a glass transition temperature of 200°C or higher include aromatic polyamides, aromatic polyimides, aromatic polyamide-imides, aromatic polyesters, and polyethersulfones.

[0028] Examples of heat-resistant resins with ionic conductivity and a glass transition temperature of 200°C or higher include aromatic polyamides, aromatic polyimides, aromatic polyamide-imides, aromatic polyesters, and resins in which at least some atoms of the main chain of polyethersulfone are substituted with functional groups having anions.

[0029] In heat-resistant resins having ionic conductivity, hydrogen atoms in the main chain of the heat-resistant resin, as well as hydrogen atoms in hydroxyl groups, carboxyl groups, amide groups, and amino groups, are substituted with functional groups having anions. More specifically, hydrogen atoms in aromatic rings, hydrogen atoms in amide groups of amide bonds, hydrogen atoms in hydroxyl groups of aliphatic or aromatic alcohols, and hydrogen atoms in amino groups of aliphatic or aromatic amines are substituted with functional groups having anions. Techniques known in the field of organic chemistry can be used for the substitution of functional groups. For example, functional groups can be substituted by nucleophilic or electrophilic reactions.

[0030] As a heat-resistant resin having ionic conductivity, it is preferable that the main chain of an aromatic polyamide, aromatic polyimide, aromatic polyamide-imide, aromatic polyester, or polyethersulfone has at least some atoms substituted with a sulfonate group, alkyl sulfonate group, carboxylate group, alkyl carboxylate group, phosphonate group, alkyl phosphonate group, trifluoroborate group, or alkyl trifluoroborate group.

[0031] [2. Solid electrolyte-containing layer and all-solid-state secondary battery equipped therewith] [2.1. Solid electrolyte-containing layer] Refer to Figures 1 and 2. The all-solid-state secondary batteries 100a and 100b comprise solid electrolyte-containing layers 50a and 50b. The solid electrolyte-containing layers 50a and 50b contain a solid electrolyte and a heat-resistant resin having ion conductivity. More specifically, the solid electrolyte-containing layers 50a and 50b comprise a solid electrolyte layer 20 containing a solid electrolyte and a resin layer 28 containing a heat-resistant resin having ion conductivity. The solid electrolyte layer 20 and the resin layer 28 are adjacent to each other.

[0032] The resin layer 28 is preferably placed between the solid electrolyte layer 20 and the negative electrode 30. Between the solid electrolyte layer 20 and the positive electrode 10, the resin layer 28 may or may not be provided (all-solid-state secondary battery 100a and solid electrolyte-containing layer 50a), or the resin layer 28 may be provided (all-solid-state secondary battery 100b and solid electrolyte-containing layer 50b).

[0033] Figure 1 shows a solid electrolyte-containing layer 50a in which the resin layer 28 is laminated on one side of the solid electrolyte layer 20. Figure 2 shows a solid electrolyte-containing layer 50b in which the resin layer 28 is laminated on both sides of the solid electrolyte layer 20. From the viewpoint of miniaturizing the all-solid-state secondary battery, it is preferable that the resin layer 28 be provided on one side of the solid electrolyte layer 20 (i.e., the form of the all-solid-state secondary battery 100a is preferred).

[0034] All-solid-state secondary batteries using a solid electrolyte have a problem with dendrite formation. Specifically, during charge-discharge cycles and constant-voltage charging, metal (e.g., metallic lithium) is generally deposited in a dendritic pattern on the negative electrode side. This dendritic metal (dendrite) grows along the grain boundaries of the solid electrolyte from the negative electrode side toward the positive electrode side, causing a short circuit between the positive and negative electrodes. In this invention, this problem is solved by providing solid electrolyte-containing layers 50a, 50a.

[0035] All-solid-state rechargeable batteries do not use flammable organic solvents as electrolytes, thus posing a low risk of ignition and combustion, and are inherently safer. Therefore, unlike conventional liquid-based rechargeable batteries, a cooling system is considered unnecessary, and use at higher temperatures is anticipated. Furthermore, to enhance the ionic conductivity of the solid electrolyte, it is also envisioned that all-solid-state rechargeable batteries may be heated externally using heating elements such as heaters. In this case, the interior of the all-solid-state rechargeable battery may reach a high temperature (approximately 150°C or higher) due to the heat generated during charging and discharging. The inventors have newly discovered that even if a resin layer is provided between the solid electrolyte layer 20 and the negative electrode 30 in such a high-temperature environment, if the resin lacks heat resistance, the resin may soften or melt, or the resin layer itself may deform, making it easier for dendrites to penetrate the resin layer. Therefore, it is desirable that the layer provided between the solid electrolyte layer 20 and the negative electrode 30 does not soften, melt, or deform even in a high-temperature environment.

[0036] Therefore, in this invention, a heat-resistant resin having ion conductivity is used for the resin layer 28. Because the heat-resistant resin having ion conductivity has excellent heat resistance, it is less likely to soften, melt, or deform even in high-temperature environments. This solves the above-mentioned problems. The resin layer 28 physically inhibits the dendrites formed on the negative electrode 30 with the heat-resistant resin having ion conductivity, thereby preventing short circuits between the electrodes. In addition, since the solid electrolyte layer 20 and the negative electrode 30 do not come into direct contact and the negative electrode 30 forms a good interface, the formation of dendrite nuclei on the surface of the negative electrode 30 can be suppressed.

[0037] The glass transition temperature of the heat-resistant resin having ionic conductivity is preferably 200°C or higher, and more preferably 250°C or higher. If the glass transition temperature of the heat-resistant resin having ionic conductivity is 200°C or higher, as described above, melting, softening, and deformation of the resin layer 28 can be better prevented even if the inside of the all-solid-state secondary batteries 100a and 100b becomes a high-temperature environment.

[0038] Incidentally, the inventors have also discovered that if a layer containing only a heat-resistant resin that does not have ionic conductivity is provided between the solid electrolyte layer 20 and the negative electrode 30, the all-solid-state secondary batteries 100a and 100b will not function as batteries due to high resistance. Therefore, a heat-resistant resin with ionic conductivity is used as the resin contained in the resin layer 28.

[0039] [2.2. Resin layer] The resin layer 28 contains a heat-resistant resin that has ionic conductivity. The heat-resistant resin that has ionic conductivity has been explained in Section [1], so a further explanation will be omitted.

[0040] The resin layer 28 may contain other materials in addition to the heat-resistant resin having ionic conductivity. Examples of other materials include ionic conductive substances and other resins. Specific examples of ionic conductive substances include at least one selected from ionic liquids, mixtures of ionic liquids and lithium salts, and polymer electrolytes. Examples of other resins include the substances exemplified in Section [2.3].

[0041] An ionic liquid is a substance that contains cations and anions and has a melting point of 100°C or less (preferably a substance that is liquid at room temperature (e.g., 25°C)). The cations contained in an ionic liquid are generally organic cations (or complex ions in which an organic ligand is coordinated to an inorganic cation). Examples of cations include ammonium cations (imidazolium salts, pyridinium salts, etc.), phosphonium ion cations, alkali metal cations, and alkaline earth metal cations. Examples of anions include halogen anions (bromide ions, etc.), boron anions (tetrafluoroborate, etc.), phosphorus anions (hexafluorophosphate, etc.), and sulfonylime anions (bis(trifluoromethylsulfonyl)imide (TFSI), bis(fluorosulfonyl)imide (FSI), etc.). Examples of organic ligands that coordinate to inorganic cations (lithium ions, etc.) include triglyme and tetraglyme. An ionic liquid may also be a mixture of a lithium salt and a nonionic organic ligand. For example, a mixture of lithium salt and tetraglyme can be considered. In this case, the cations contained in the ionic liquid are lithium-containing complex ions, and the anions are the anions that were contained in the lithium salt.

[0042] Examples of lithium salts in mixtures of ionic liquids and lithium salts include lithium hexafluoride phosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium bis(fluorosulfonyl)imide (LiFSI:LiN(SO2F)2), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI:LiN(SO2CF3)2), lithium bis(perfluoroethylsulfonyl)imide (LiN(SO2C2F5)2), LiAsF6, LiCF3SO3, and lithium difluoro(oxalate)borate.

[0043] Polymer electrolytes are mixtures of polymer compounds with molecular polarity and lithium salts. Examples of polymer compounds with molecular polarity include compounds with alkylene oxide structures (ethylene oxide structures, propylene oxide structures, etc.), polyethyleneimine polymers, polyalkylene sulfide polymers, and polyvinylpyrrolidone polymers. Such polymer compounds can contain a large amount of lithium salt, thereby increasing ionic conductivity. Examples of lithium salts contained in polymer electrolytes include the compounds exemplified as lithium salts in mixtures of ionic liquids and lithium salts.

[0044] In the resin layer 28, the lower limit of the weight of the ion-conducting heat-resistant resin is preferably 10% by weight or more, more preferably 20% by weight or more, and even more preferably 30% by weight or more, based on 100% by weight of the resin layer 28. The upper limit of the weight of the ion-conducting heat-resistant resin is not particularly limited, but may be 99% by weight or less or 95% by weight or less. In one embodiment, the resin layer 28 may consist substantially only of the ion-conducting heat-resistant resin. Including the ion-conducting heat-resistant resin in the above proportions can more reliably prevent short circuits caused by dendrite formation.

[0045] The lower limit of the thickness of the resin layer 28 is preferably 0.1 μm or more, and more preferably 0.5 μm or more. The upper limit of the thickness of the resin layer 28 is preferably 500 μm or less, and more preferably 250 μm or less. The lower limit of the ionic conductivity (e.g., lithium ion conductivity) of the resin layer 28 is 10 at 80°C. -10 Preferably S / cm or higher, 10 -9 S / cm or more is more preferable, 10 -8 A value of S / cm or higher is even more preferable. A method for measuring the ionic conductivity of the resin layer 28 is the impedance method described in Section [1].

[0046] [2.3. Form and Manufacturing Method of Resin Layers] The resin layer 28 can take various forms. For example, the ion-conducting heat-resistant resin may be uniformly distributed or localized within the resin layer 28. An example of the former is a layer made of an ion-conducting heat-resistant resin. An example of the latter is a layer in which an ion-conducting heat-resistant resin and another resin are laminated together.

[0047] Examples of methods for manufacturing the resin layer 28 include the following (a), (b), and (c). (a) A method of forming a resin layer 28 by processing a heat-resistant resin having ionic conductivity into a porous material (porous membrane, nonwoven fabric, etc.). From the viewpoint of thinning the resin layer 28, a porous membrane is preferred as the porous material. (b) A method of preparing a porous material containing an ion-conductive heat-resistant resin and other substances (a porous membrane in which an ion-conductive heat-resistant resin and other resins are laminated; a porous membrane impregnated with an ion-conductive heat-resistant resin; a nonwoven fabric in which an ion-conductive heat-resistant resin and other resins are blended) to form the resin layer 28. For the same reasons as in (a), a porous membrane is preferred as the porous material. (c) A method for obtaining a resin layer 28 by forming a heat-resistant resin having ionic conductivity. Examples of film formation methods include a wet method using a solvent and a dry method by pressing a mixture.

[0048] Here, the term "porous material" in embodiments (a) and (b) refers to an object that has a large number of pores and is capable of passing gas or liquid from one surface to the other.

[0049] The pore size of the porous material is not particularly limited, but is preferably 0.3 μm or less, and more preferably 0.14 μm or less. The basis weight per unit area of ​​the porous material is not particularly limited, but is 4 to 20 g / m². 2 Preferably, 4-12 g / m 2 More preferably, 5-12 g / m 2This is even more preferable. The air permeability of the porous material is preferably 30 to 500 seconds / 100 mL, and more preferably 50 to 300 seconds / 100 mL, as measured in Gaarle values ​​according to JIS P8117.

[0050] Furthermore, the "other resin" in embodiment (b) above may include, for example, polyolefins. Specific examples of polyolefins include homopolymers and copolymers obtained by polymerizing (or copolymerizing) monomers such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, and 1-hexene. Examples of such homopolymers include polyethylene, polypropylene, and polybutene. An example of such copolymer is ethylene-propylene copolymer. Among these resins, polyethylene is preferred. Examples of polyethylene include low-density polyethylene, high-density polyethylene, linear polyethylene (ethylene-α-olefin copolymer), and ultra-high molecular weight polyethylene with a weight-average molecular weight of 1 million or more. Among these, ultra-high molecular weight polyethylene is particularly preferred.

[0051] The resin layer 28 is a short-circuit prevention layer that has the function of preventing short circuits, preventing short circuits caused by dendrites even in high-temperature environments, and is a layer that has sufficient ionic conductivity. For this reason, the resin layer 28 can be described as "a short-circuit prevention layer for all-solid-state secondary batteries containing a heat-resistant resin with ionic conductivity." Here, whether or not the resin layer 28 has the function of preventing short circuits (i.e., whether or not it can prevent short circuits caused by dendrites in high-temperature environments) can be determined by the following procedure. 1. The following dendrite resistance test is subjected to a CR2032 coin-type lithium battery as an evaluation cell (hereinafter sometimes referred to as a coin cell). 2. After 5 minutes from the start of the test, the coin cell that showed a nearly constant negative voltage was disassembled and the solid electrolyte layer was removed. 3. Observe the surface of the extracted solid electrolyte layer. If there are fewer than 10 black dots (i.e., dendrite marks) on the surface of the solid electrolyte layer, it will be judged to have the function of preventing short circuits.

[0052] (Dentlite resistance test) Using coin cells, the following test laminate will be fabricated. A 0.10 mA / cm² load will be applied to this laminate. 2 The voltage change over time is observed when a current is passed through the negative electrode to continuously deposit metallic lithium. The test temperature is 85°C or 90°C.

[0053] The layer configuration of the test laminate is as follows: Stainless steel plate, thickness: 500 μm, diameter: 15.5 mm • Lithium foil on the eluting side (positive electrode 10), thickness: 500 μm, diameter: 13 mm • Solid electrolyte layer 20 (for example, Li manufactured by Toyoshima Seisakusho Co., Ltd.) 6.75 La3Zr 1.75 Nb 0.25 O 12 (Sintered body, 500 μm thick, 15 mm in diameter) ·Resin layer 28, diameter: 16mm • Deposition side: Lithium metal foil (negative electrode 30), thickness: 500 μm, diameter: 13 mm.

[0054] In dentite resistance tests, if no short circuit occurs and metallic lithium is stably deposited on the negative electrode 30, the coin cell will exhibit a nearly constant negative voltage. On the other hand, if a complete short circuit occurs due to dendrites, the voltage of the coin cell will show 0V. Furthermore, if small short circuits (micro-shorts) are repeatedly caused by dendrites, the voltage of the coin cell will fluctuate wildly between 0V and negative values.

[0055] Furthermore, the absence of dendritic traces on the surface of the solid electrolyte layer 20 after the dendritic resistance test indicates that the resin layer 28 suppressed dendritic growth and prevented dendrites from penetrating the solid electrolyte layer.

[0056] [2.4.Solid electrolyte layer] The solid electrolyte layer 20 is a layer containing at least a solid electrolyte. The solid electrolyte layer 20 is a different layer from the resin layer 28. For example, the weight of the heat-resistant resin having ion conductivity in the solid electrolyte layer 20 is less than 1% by weight.

[0057] The lower limit of the thickness of the solid electrolyte layer 20 is, for example, 5 μm or more, and the upper limit is, for example, 500 μm or less. The lithium ion conductivity of the solid electrolyte 20 at 25°C is, for example, 1 × 10⁻¹⁶. -5 S / cm or higher is preferred, 1 × 10 -4 A S / cm or higher is more preferable.

[0058] A method for measuring the lithium ion conductivity of the solid electrolyte layer 20 at 25°C is to use the impedance method described in Section [1], with the solid electrolyte as the sample to be measured.

[0059] Solid electrolytes include inorganic solid electrolytes and organic solid electrolytes. Examples of inorganic solid electrolytes include sulfide-based solid electrolytes, oxide-based solid electrolytes, and nitride-based solid electrolytes. Examples of organic solid electrolytes include polymer electrolytes and gel electrolytes.

[0060] Of these solid electrolytes, sulfide-based and oxide-based solid electrolytes are prone to dendrite formation along the grain boundaries of the electrolyte particles. The resin layer 28 can suppress dendrite formation even when using sulfide-based or oxide-based solid electrolytes, and can prevent short circuits between electrodes caused by dendrite formation. Furthermore, sulfide-based solid electrolytes may generate toxic gases such as hydrogen sulfide when exposed to the atmosphere, whereas oxide-based solid electrolytes do not. Therefore, from the viewpoint of safety for all-solid-state secondary batteries, it is preferable to use oxide-based solid electrolytes as inorganic solid electrolytics.

[0061] (Inorganic solid electrolyte) Sulfide-based solid electrolytes typically contain lithium and sulfur. Furthermore, it is preferable that sulfide-based solid electrolytes contain one or more elements selected from the group consisting of phosphorus, germanium, tin, and silicon. Additionally, sulfide-based solid electrolytes may contain one or more elements selected from the group consisting of oxygen and halogen elements (e.g., fluorine, chlorine, bromine, and iodine).

[0062] Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-P2S5-GeS2, Li2S-P2S5-SnS2, Li2S-P2S5-SiS2, Li2S-P2S5-LiI, Li2S-P2S5-LiI-LiBr, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, and Li2S-P2S5-Z. m S n (m and n are positive numbers, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li x MO y Examples include (where x and y are positive numbers, and M is P, Si, Ge, B, Al, Ga, or In). Here, the notation "AB" means "a material made using a raw material composition containing A and B." For example, "Li2S-P2S5" means "a material made using a raw material composition containing Li2S and P2S5."

[0063] Examples of oxide-based solid electrolytes include NASICON-type solid electrolytes (LiTi2(PO4)3 and its elemental substitutions (Li 1+x Al x Ti 2-x (PO4)3, Li 1+x+y Al x Ti 2-x P 3-y Si y O 12(e.g.) ); Perovskite-type solid electrolytes ((LaLi)TiO3 and La 1-3x Li 3x Representative of TiO3); LISICON-type solid electrolytes (Li4SiO4, LiGeO4 and their elemental substitutions (Li 4-2x Zn x GeO4, for example. Li 14 ZnGe4O 16 ) is a representative example of glass-ceramic solid electrolytes (Li 1.5 Al 0.5 Ge 1.5 (PO4)3 is a representative example; Li3N and its H-substituted derivatives; Li3PO4 and its N-substituted derivatives (Li 2.9 PO 3.3 N 0.46 Examples include (LIPON), etc.

[0064] Oxide-based solid electrolytes may have a garnet-type crystal structure. Garnet-type solid electrolytes have high lithium-ion conductivity and are stable against moisture, oxygen, lithium metal, etc.

[0065] Garnet-type crystals are typically A3B2C3O 12 It is represented by the chemical formula and can have a cubic crystal structure. An example of a garnet-type solid electrolyte is a composite oxide containing Li, La, and Zr, a more specific example being Li7La3Zr2O 12 (LLZ) is one example. Garnet-type solid electrolytes may contain one or more substitutional elements selected from the group consisting of Al, Mg, Ca, Sr, Ba, Ta, Nb, and Yb. An example of an elemental substitution of LLZ is Li 7-3x Al x La3Zr2O 12 Li 7-x La3Zr 2-y M y O 12 (M can be a pentavalent element such as Nb or Ta.)

[0066] The inorganic solid electrolyte may be glass, glass ceramic, or crystalline material. Glass is obtained by amorphous treatment of a raw material composition (e.g., a mixture of Li2S and P2S5). Examples of amorphous treatment include mechanical milling. Glass ceramic is obtained by heat treatment of glass. Crystalline material is obtained, for example, by solid-phase reaction treatment of a raw material composition.

[0067] When the solid electrolyte layer 20 is formed from an inorganic solid electrolyte, the shape of the inorganic solid electrolyte is preferably pelletized. The thickness of the pelletized inorganic solid electrolyte is preferably 1 mm or less, and more preferably 500 μm or less. The lithium ion conductivity of the inorganic solid electrolyte at 25°C is, for example, 1 × 10⁻¹⁶. -5 S / cm or higher is preferred, 1 × 10 -4 A value of S / cm or higher is more preferable. As a method for measuring the lithium ion conductivity of inorganic solid electrolytes at 25°C, the impedance method described in Section [1] can be used.

[0068] (organic solid electrolyte) Examples of polymer electrolytes among organic solid electrolytes include the substances exemplified in Section [2.2.].

[0069] A gel electrolyte is, for example, a mixture of a polymer compound with gelling properties and a non-aqueous electrolyte. The gel electrolyte is a polymer compound that retains the non-aqueous electrolyte, possessing moderate plasticity and tackiness, and also having ionic conductivity close to that of the non-aqueous electrolyte. Therefore, all-solid-state secondary batteries using gel electrolytes can achieve high charge-discharge efficiency. The mixing ratio of the polymer compound to the non-aqueous electrolyte can be (2:3) to (3:2) from the viewpoint of obtaining moderate plasticity.

[0070] Examples of polymer compounds with gelling properties include fluororesins containing vinylidene fluoride units, acrylic resins containing (meth)acrylic acid units (the (meth)acrylic acid units may be esterified), and polyether resins containing polyalkylene oxide units. Examples of fluororesins containing vinylidene fluoride units include polyvinylidene fluoride, copolymers containing vinylidene fluoride units and hexafluoropropylene units, and copolymers containing vinylidene fluoride units and trifluoroethylene units. In addition, polymer compounds used as polymer electrolytes (for example, compounds having an alkylene oxide structure) can also be used.

[0071] The non-aqueous electrolyte contained in the gel electrolyte contains a lithium salt and a non-aqueous solvent that dissolves the lithium salt. Examples of lithium salts include the substances exemplified in Section [2.2.]. Examples of non-aqueous solvents include cyclic carbonate esters, linear carbonate esters, carboxylic acid esters, cyclic ethers, linear ethers, nitriles, and amides.

[0072] [2.5. All-solid-state secondary battery] Figure 1 is a schematic diagram representing an all-solid-state secondary battery according to one aspect of the present invention. The all-solid-state secondary battery 100a comprises a positive electrode 10, a solid electrolyte-containing layer 50a, and a negative electrode 30. Here, the solid electrolyte-containing layer 50a is arranged such that a resin layer 28 is located between the solid electrolyte layer 20 and the negative electrode 30. In the solid electrolyte-containing layer 50a in Figure 1, the resin layer 28 is provided on one side of the solid electrolyte layer 20. Therefore, there is no resin layer 28 between the positive electrode 10 and the solid electrolyte layer 20.

[0073] Figure 2 is a schematic diagram representing another embodiment of the all-solid-state secondary battery of the present invention. In the solid electrolyte-containing layer 50b included in the all-solid-state secondary battery 100b, a resin layer 28 is provided on both sides of the solid electrolyte layer 20. Therefore, a resin layer 28 is also present between the positive electrode 10 and the solid electrolyte layer 20.

[0074] In this specification, "all-solid-state secondary battery" refers to a secondary battery that uses a solid electrolyte as the electrolyte, that is, a secondary battery equipped with a solid electrolyte. In one embodiment, the all-solid-state secondary batteries 100a and 100b do not contain an electrolyte solution (for example, an aqueous electrolyte solution or a non-aqueous electrolyte solution).

[0075] The form of the all-solid-state secondary batteries 100a and 100b is not particularly limited. Examples of forms include coin-type batteries, laminate-type batteries, cylindrical batteries, and prismatic batteries. All-solid-state secondary batteries can be repeatedly charged and discharged, but they can also be used like primary batteries. That is, a charged all-solid-state secondary battery may be used for a one-time discharge.

[0076] The all-solid-state secondary batteries 100a and 100b are, for example, all-solid-state lithium secondary batteries and all-solid-state sodium secondary batteries, and are preferably all-solid-state lithium secondary batteries.

[0077] The applications of the all-solid-state secondary batteries 100a and 100b are not particularly limited. Examples of applications include mobile applications (electric vehicles, electric motorcycles, electric-assist bicycles, trains, etc.), industrial machinery applications (construction machinery, forklifts, elevators, etc.), stationary power supply applications (solar power generation, wind power generation, UPS, medical equipment, etc.), and consumer applications (mobile PCs, smartphones, etc.).

[0078] The following describes the components of the all-solid-state secondary batteries 100a and 100b, excluding the solid electrolyte-containing layers 50a and 50b, individually.

[0079] (positive electrode) The positive electrode 10 comprises, for example, a positive electrode active material layer and a positive electrode current collector.

[0080] The positive electrode active material layer is a layer that contains at least positive electrode active material. Examples of positive electrode active materials include oxide-based active materials and sulfur-based active materials.

[0081] Examples of oxide-based active materials include rock salt layer-structured active materials (such as LiCoO2, LiMnO2, LiNiO2, LiVO2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, etc.); spinel-type active materials (such as LiMn2O4, Li4Ti5O 12 , Li(Ni 0.5 Mn 1.5 )O4, etc.); olivine-type active materials (such as LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, etc.). Other examples of oxide-based active materials include Li 1+x Mn 2-x-y M y O4 (M is one or more selected from the group consisting of Al, Mg, Co, Fe, Ni, and Zn, and 0 < x + y < 2), which is a LiMn spinel active material; lithium titanate.

[0082] A coating layer containing a Li-ion conductive oxide may be provided on the surface of the oxide-based active material. By providing the coating layer, the reaction between the oxide-based active material and the solid electrolyte can be suppressed. Examples of the Li-ion conductive oxide include LiNbO3, Li4Ti5O 12 , Li3PO4. The lower limit value of the thickness of the coating layer can be, for example, 0.1 nm or more or 1 nm or more. The upper limit value of the thickness of the coating layer can be, for example, 100 nm or less or 20 nm or less. The coverage rate of the coating layer on the surface of the oxide-based active material is, for example, 70% or more or 90% or more.

[0083] Sulfur-based active materials are active materials that contain at least sulfur element. Sulfur-based active materials may or may not contain Li element. Examples of sulfur-based active materials include elemental sulfur, lithium sulfide (Li2S), polysulfide lithium (Li2S x ; 2 ≤ x ≤ 8).

[0084] The positive electrode active material layer may optionally contain one or more materials selected from the group consisting of an inorganic solid electrolyte, a conductive material, and a binder. Examples of inorganic solid electrolytes include those described in Section [2.4.]. Examples of conductive materials include acetylene black, Ketjen black, and carbon fiber. Examples of binders include rubber-based binders (such as butylene rubber (BR) and styrene-butadiene rubber (SBR)); and fluoride-based binders (such as polyvinylidene fluoride (PVDF)).

[0085] The lower limit of the thickness of the positive electrode active material layer is, for example, 0.1 μm or more. The upper limit of the thickness of the positive electrode active material layer is, for example, 300 μm or less or 100 μm or less.

[0086] Examples of materials for the positive electrode current collector include stainless steel, aluminum, nickel, iron, titanium, and carbon. Examples of shapes for the positive electrode current collector include foil and plate. The lower limit of the thickness of the positive electrode current collector is, for example, 0.1 μm or more or 1 μm or more. The upper limit of the thickness of the positive electrode current collector is, for example, 1 mm or less or 100 μm or less.

[0087] (Negative electrode) The negative electrode 30 comprises, for example, a negative electrode active material layer and a negative electrode current collector.

[0088] The negative electrode active material layer is a layer that contains at least a negative electrode active material. Examples of negative electrode active materials include lithium metal, lithium alloys, metals that alloy with lithium, carbon-based materials, and oxide-based materials.

[0089] Examples of carbon-based materials include graphite, amorphous carbon, carbon nanotubes, and graphene. An example of an oxide-based material is Li4Ti5O 12 Examples include (LTO) and TiO2.

[0090] The negative electrode active material layer may optionally contain one or more substances selected from the group consisting of an inorganic solid electrolyte, a conductive material, and a binder. Examples of these substances include the inorganic solid electrolyte, conductive material, and binder that may be included in the positive electrode active material layer, as exemplified in the (positive electrode) section of [2.5.].

[0091] The lower limit of the thickness of the negative electrode active material layer is, for example, 0.1 μm or more. The upper limit of the thickness of the negative electrode active material layer is, for example, 300 μm or less or 100 μm or less.

[0092] Examples of materials for the negative electrode current collector include materials that do not alloy with Li. More specific examples include stainless steel, copper, nickel, and carbon. Examples of shapes for the negative electrode current collector include foil and plate shapes. The lower limit of the thickness of the negative electrode current collector is, for example, 0.1 μm or more or 1 μm or more. The upper limit of the thickness of the negative electrode current collector is, for example, 1 mm or less or 100 μm or less.

[0093] [2.6. Method for manufacturing all-solid-state secondary batteries] One aspect of the present invention is a method for manufacturing all-solid-state secondary batteries 100a and 100b, which includes the step of arranging solid electrolyte-containing layers 50a and 50b between a positive electrode 10 and a negative electrode 30. In one embodiment, this manufacturing method includes the step of arranging a resin layer 28 between a solid electrolyte layer 20 and a negative electrode 30.

[0094] An example of a method for arranging the resin layer 28 between the solid electrolyte layer 20 and the negative electrode 30 is as follows: (α) A method of placing the resin layer 28 between the solid electrolyte layer 20 and the negative electrode 30 after it has been fabricated. For example, a method of placing a sheet-like resin layer 28 on top of the solid electrolyte layer 20 or the negative electrode 30. (β) A method for producing a resin layer 28 by coating a solid electrolyte layer 20 or a negative electrode 30 with a solution containing an ion-conductive heat-resistant resin. For example, (i) prepare a solution containing an ion-conductive heat-resistant resin and a solvent, (ii) coat the solution onto the solid electrolyte layer 20 or a negative electrode 30, and (iii) dry to remove the solvent. (γ) A method for producing a resin layer 28 by placing a powder containing an ion-conductive heat-resistant resin on a solid electrolyte layer 20 or a negative electrode 30 and molding it. For example, (i) prepare a powder containing an ion-conductive heat-resistant resin, (ii) place the powder on a solid electrolyte layer 20 or a negative electrode 30, and (iii) press mold it.

[0095] (Manufacturing of 100A all-solid-state rechargeable battery) According to the above methods (α) to (γ), a solid electrolyte-containing layer 50a having only one resin layer 28 can be produced. If a positive electrode 10 is further laminated on the solid electrolyte layer 20 of this solid electrolyte-containing layer 50a, a laminate (all-solid-state secondary battery 100a) can be produced in which the positive electrode 10, solid electrolyte layer 20, resin layer 28, and negative electrode 30 are laminated in this order.

[0096] (Manufacturing of all-solid-state secondary battery 100b) According to the above methods (α) to (γ), a solid electrolyte-containing layer 50a having only one resin layer 28 can be produced. By further laminating the resin layer 28 and the positive electrode 10 on the solid electrolyte layer 20 of this solid electrolyte-containing layer 50a, a laminate (all-solid-state secondary battery 100b) can be produced in which the positive electrode 10, resin layer 28, solid electrolyte layer 20, resin layer 28, and negative electrode 30 are laminated in this order.

[0097] The solid electrolyte layer 20 or the negative electrode 30 described above may each be a precursor. That is, the positive electrode 10, the solid electrolyte layer 20, or the negative electrode 30 may be formed after the above-mentioned steps by heating, compression, or the like. A precursor is a compound or mixture that becomes the positive electrode 10, the solid electrolyte layer 20, or the negative electrode 30 by heating, compression, or the like.

[0098] Furthermore, in the above-described manufacturing method, the positive electrode 10, the solid electrolyte layer 20, and the negative electrode 30 may be manufactured by known methods. For example, these layers can be manufactured by a wet method of drying the raw material slurry, or by a powder molding method of pressing the raw material powder. If the solid electrolyte layer 20 is an organic solid electrolyte layer, the solid electrolyte layer 20 can be manufactured by known polymerization methods or the like.

[0099] Although not shown in the diagram, the all-solid-state secondary batteries 100a and 100b may include a housing to enclose the laminate, leads for extracting current from the electrodes, etc. Conventional known methods can be used to manufacture these components and assemble the battery product.

[0100] The contents described in each of the above sections can be appropriately applied to other sections as well. The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Therefore, embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0101] All patent documents cited herein are incorporated herein by reference.

[0102] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. [Examples]

[0103] [Synthesis example: Synthesis of heat-resistant resin with ionic conductivity] Based on a previous report (Melinda B. Gieselman and John R. Reynolds (1990) "Poly[(p-phenyleneterephthalamido)propanesulfonate]: a new polyelectrolyte for application to conducting molecular composites", Macromolecules, vol.23 (issue 12), pp.3118-3124), the hydrogen atoms of the amide groups in poly(p-phenyleneterephthalamide) were replaced with propanesulfonate groups. The specific procedure is as follows. In the procedure below, the amounts of poly(p-phenyleneterephthalamide), sodium hydride (NaH), and 1,3-propanesultone used are all equal to 1 equivalent relative to the amide groups in poly(p-phenyleneterephthalamide). 1. 139 g of dimethyl sulfoxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., ultra-dehydrated) and 0.50 g of NaH (manufactured by Sigma-Aldrich, 60% mineral oil dispersion) were charged into a nitrogen-purged reaction vessel. The reaction system was heated to 70°C over 2.1 hours. Next, the reaction system was maintained at 70°C for 15 minutes. Then, the reaction system was cooled to 30°C. 3.50 g of poly(p-phenylene terephthalamide) was added to the reaction system and stirred at 60°C for 1.5 hours. Next, the temperature of the reaction system was cooled to below 40°C. 4.1.54 g of 1,3-propanesultone (Sigma-Aldrich, ≥99%, acid < 200 ppm, H2O < 100 ppm) was added to the reaction system and stirred. Stirring was carried out for 3 days. The stirring conditions were 40°C for 1 hour on day 1, 40°C for 10 hours on day 2, and 60°C for 3 hours on day 3. 5.251 g of tetrahydrofuran (manufactured by Fujifilm Wako Pure Chemical Industries, ultra-dehydrated, containing stabilizer) was added to the reaction system and left for 1 hour to separate the reaction system into liquid and solid phases. The solid phase was extracted by decantation. 6. To the obtained solid phase, approximately the same volume was added by visual estimation. After standing for 3 days, the solid phase was extracted by decantation. 7. Tetrahydrofuran was added to the obtained solid phase and stirred for about 1 hour. Next, the reaction mixture was filtered under a nitrogen atmosphere and the solvent was removed by vacuum drying (50°C, about 33 hours).

[0104] In this manner, 2.60 g of the product was obtained (yield: 88%). This product was an orange resin and exhibited hygroscopic properties. It was soluble in water and dimethyl sulfoxide, but insoluble in dimethyl carbonate, isopropyl alcohol, and N-methylpyrrolidone.

[0105] In this manner, 2.60 g of the product was obtained (yield: 88%). The product was an orange powder and exhibited hygroscopic properties. It was soluble in water and dimethyl sulfoxide, but insoluble in dimethyl carbonate, isopropyl alcohol, and N-methylpyrrolidone.

[0106] When the infrared absorption spectrum of the product was measured using the KBr tablet molding method, a spectrum in good agreement with the previously reported one was obtained. In particular, the peaks corresponding to the symmetric and asymmetric stretching vibrations of the S=O bond site were approximately 1200 cm². -1 and approximately 1150cm -1 A peak was also observed. From this, it was determined that a heat-resistant resin with the desired ionic conductivity (a resin in which the hydrogen atoms of the amide groups contained in poly(p-phenylene terephthalamide) are replaced with propanesulfonate groups, amount of propanesulfonate groups: 50-66 mol%) was obtained.

[0107] [Confirmation of heat resistance] The obtained product was subjected to differential thermal analysis. The measurement conditions were a temperature range of 40°C to 250°C and a heating rate of 10°C / min. The DSC curve during the second heating cycle was analyzed. As a result, it was confirmed that there was no glass transition temperature up to 250°C. In other words, the glass transition temperature of the obtained ionic conductive resin is above 250°C.

[0108] [Measurement of Ionic Conductivity] The ionic conductivity of the heat-resistant resin having the obtained ionic conductivity was 2.4×10 -8 S / cm. The measurement was based on the impedance method and specifically followed the following procedure. 1. Ethanol was added as a wetting agent to the resin that had absorbed water to prepare a solution. Next, this solution was impregnated into a polyethylene porous film and dried under reduced pressure at 50°C for 33 hours. In this way, a measurement sample was prepared. 2. Inside a glove box, under a dry argon atmosphere, the measurement sample was sandwiched between two blocking electrodes (for example, electrodes made of SUS), and a coin-type lithium battery CR2032 (coin cell) was fabricated. 3. The obtained coin cell was conditioned in a thermostatic bath at 80°C for 12 hours. 4. Using an impedance measuring device, the measurement was carried out at 80°C in the frequency range from 0.1 Hz to 1 MHz with an amplitude of 10 mV. The ionic conductivity σ was calculated from the following formula. σ (S / cm) = t (cm) × R (Ω) / A (cm 2 ) In the formula, R represents the value of the impedance. A represents the area of the sample. t represents the thickness of the sample.

[0109] [Example] The dendrite suppression effect and voltage stabilization effect by using the resin layer were verified by a dendrite resistance test. In this test, a coin-type lithium battery CR2032 was used as an evaluation cell. Specifically, each layer was laminated in the following order to fabricate a test laminate (stainless steel plate / dissolved-side metallic lithium foil / solid electrolyte-containing layer / deposited-side metallic lithium foil). A current of 0.10 mA / cm 2 was passed through this test laminate, and the voltage behavior over time was observed. The current density mentioned above was for an LLZN sintered pellet (Li 6.75 La3Zr 1.75 Nb 0.25 O 12This is the limiting current density when a deposition-dissolution cycle test is imposed using a pellet thickness of 500 μm. That is, it is the limiting current density when a deposition-dissolution cycle test is imposed without using a resin layer. The test temperature was 85°C in Example 1, 95°C in Example 2, and 85°C in Comparative Examples 1 and 2. · Stainless steel plate, thickness: 500 μm, diameter: 15.5 mm · Dissolution-side metallic lithium foil, thickness: 500 μm, diameter: 13 mm · Deposition-side metallic lithium foil, thickness: 500 μm, diameter: 13 mm.

[0110] [Example 1] A heat-resistant resin having ion conductivity obtained in the synthesis example was dissolved in dimethyl sulfoxide to prepare a solution. Next, this solution was applied to one surface of a solid electrolyte layer (manufactured by Toyoshima Seisakusho Co., Ltd., sintered body of Li 6.75 La3Zr 1.75 Nb 0.25 O 12 with a thickness of 500 μm, a diameter of 15 mm, and an ion conductivity of 1.0×10 -5 S / cm at 25°C), and dried under reduced pressure at 50°C for 12 hours. In this way, a solid electrolyte-containing layer in which a resin layer 1 was laminated on the solid electrolyte layer was obtained. Using the obtained solid electrolyte-containing layer, a dendrite resistance test was carried out.

[0111] [Example 2] A heat-resistant resin having ion conductivity obtained in the synthesis example was吸湿 with water, and ethanol was added as a wetting agent to prepare a solution. Next, this solution was impregnated into a polyethylene porous film and dried under reduced pressure at 50°C for 33 hours. In this way, a resin layer 2 in which a heat-resistant resin having ion conductivity was impregnated into polyethylene was obtained. Next, a solid electrolyte layer (manufactured by Toyoshima Seisakusho Co., Ltd., sintered body of Li 6.75 La3Zr 1.75 Nb 0.25 O 12 with a thickness of 500 μm, a diameter of 15 mm, and an ion conductivity of 1. ×10 -5A solid electrolyte-containing layer was obtained by laminating a resin layer 2 on top of a (S / cm) layer. A dendritic resistance test was performed using the obtained solid electrolyte-containing layer.

[0112] [Comparative Example 1] Solid electrolyte layer (manufactured by Toyoshima Seisakusho Co., Ltd., Li 6.75 La3Zr 1.75 Nb 0.25 O 12 Sintered body, thickness 500 μm, diameter 15 mm, ionic conductivity at 25°C: 1.0 × 10⁻⁶ -5 A dendrite resistance test was conducted using S / cm (without resin layer).

[0113] [Comparative Example 2] Solid electrolyte layer (manufactured by Toyoshima Seisakusho Co., Ltd., Li 6.75 La3Zr 1.75 Nb 0.25 O 12 Sintered body, thickness 500 μm, diameter 15 mm, ionic conductivity at 25°C: 1.0 × 10⁻⁶ -5 Dimethyl sulfoxide was added dropwise to (S / cm) and dried under reduced pressure at 50°C for 12 hours. A dendritic resistance test was performed using the resulting solid electrolyte layer.

[0114] [result] When the solid electrolyte layers obtained in Comparative Examples 1 and 2 were used, the voltage dropped to 0V approximately 3 minutes after the start of the test. This is thought to be because a short circuit occurred due to the growth of dendrites, as there was no resin layer.

[0115] In contrast, the solid electrolyte-containing layer obtained in Example 1 did not show a voltage of 0V until approximately 6 minutes after the start of the test. Similarly, the solid electrolyte-containing layer obtained in Example 2 did not show a voltage of 0V from the start of the test until the end of the test (approximately 22 minutes later). From this, it can be concluded that the resin layer prevented short circuits between electrodes caused by dendrite formation in the solid electrolyte-containing layers obtained in Examples 1 and 2. Furthermore, comparing the examples, the solid electrolyte-containing layer obtained in Example 2 was able to prevent short circuits caused by dendrites for a longer period.

[0116] From these results, it was found that a solid electrolyte-containing layer with a resin layer can prevent short circuits between electrodes caused by dendrite formation. [Industrial applicability]

[0117] This invention can be used in all-solid-state rechargeable batteries and the like. [Explanation of symbols]

[0118] 10: Positive electrode 20: Solid electrolyte layer 28: Resin layer (short-circuit prevention layer for all-solid-state secondary batteries) 30: Negative electrode 50a: Solid electrolyte containing layer 50b: Solid electrolyte containing layer 100a: All-solid-state secondary battery 100b: All-solid-state secondary battery

Claims

1. It has a solid electrolyte layer containing a solid electrolyte and a resin layer containing a heat-resistant resin having ion conductivity. A solid electrolyte-containing layer in which the solid electrolyte layer and the resin layer are adjacent, The resin layer does not contain any ion-conducting material other than the heat-resistant resin having ion conductivity. The lithium ion conductivity of the solid electrolyte layer is 1 × 10 at 25°C. －５ It is S / cm or higher, A solid electrolyte-containing layer comprising a heat-resistant resin having ionic conductivity, wherein the glass transition temperature of the resin is 200°C or higher.

2. It has a solid electrolyte layer containing a solid electrolyte and a resin layer containing a heat-resistant resin having ion conductivity. A solid electrolyte-containing layer in which the solid electrolyte layer and the resin layer are adjacent, The thickness of the solid electrolyte layer is 5 μm or more. The lithium ion conductivity of the solid electrolyte layer is 1 × 10 at 25°C. －５ It is S / cm or higher, A solid electrolyte-containing layer comprising a heat-resistant resin having ionic conductivity, wherein the glass transition temperature of the resin is 200°C or higher.

3. The solid electrolyte-containing layer according to claim 1 or 2, wherein the solid electrolyte is an inorganic solid electrolyte.

4. An all-solid-state secondary battery comprising a positive electrode, a solid electrolyte-containing layer according to any one of claims 1 to 3, and a negative electrode.

5. A method for manufacturing an all-solid-state secondary battery, comprising the step of arranging a solid electrolyte-containing layer according to any one of claims 1 to 3 between a positive electrode and a negative electrode.

6. A short-circuit prevention layer for an all-solid-state secondary battery, comprising a heat-resistant resin having ion conductivity, The short-circuit prevention layer does not contain any ion-conducting material other than the heat-resistant resin having ion conductivity. A short-circuit prevention layer comprising a heat-resistant resin having ionic conductivity, wherein the glass transition temperature of the resin is 200°C or higher.

7. A method for preventing short circuits in an all-solid-state secondary battery, comprising arranging a solid electrolyte-containing layer according to any one of claims 1 to 3 between a positive electrode and a negative electrode.

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