Positive electrode material, positive electrode manufacturing method, positive electrode plate manufacturing method, and battery manufacturing method

Abstract

A positive electrode material 1000 contains a positive electrode active material 110, a solid electrolyte 100, and an organic solvent 111. The solid electrolyte 100 contains Li, M, O, and X. M is at least one element selected from the group consisting of Ta and Nb. X is at least one element selected from the group consisting of F, Cl, Br, and I. The organic solvent 111 has a boiling point of 212ºC or less.

Description

[Technical Field]

[0001] The present disclosure relates to a material for a positive electrode, a method for manufacturing a positive electrode, a method for manufacturing a positive electrode plate, and a method for manufacturing a battery. [Background technology]

[0002] A lithium secondary battery includes a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode. For example, an all-solid-state battery using a solid electrolyte for the electrolyte layer has been proposed as a highly safe battery.

[0003] In the production of all-solid-state batteries, the positive electrode is produced, for example, by a coating method, in which a slurry containing a positive electrode active material, a solid electrolyte, and a solvent is applied to a current collector to form a coating film, and the coating film is dried to produce the positive electrode (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-18712 Summary of the Invention

[0005] The present disclosure provides a cathode material suitable for producing a cathode that can improve the charge / discharge efficiency of a battery.

[0006] The positive electrode material of the present disclosure is a positive electrode active material; a solid electrolyte; an organic solvent; Including, the solid electrolyte comprises Li, M, O, and X; M is at least one selected from the group consisting of Ta and Nb, X is at least one selected from the group consisting of F, Cl, Br, and I; The organic solvent has a boiling point of 212°C or less.

[0007] According to the present disclosure, it is possible to provide a positive electrode material suitable for producing a positive electrode that can improve the charge / discharge efficiency of a battery. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing a positive electrode material according to the first embodiment. [Figure 2] FIG. 2 is a flowchart showing an example of a method for manufacturing a positive electrode according to the second embodiment. [Figure 3] FIG. 3 is a flowchart showing an example of a method for manufacturing a positive electrode plate according to the third embodiment. [Figure 4] FIG. 4 is a cross-sectional view showing a schematic configuration of a positive electrode plate obtained by the method for producing a positive electrode plate according to the third embodiment. [Figure 5] FIG. 5 is a schematic diagram showing the schematic configuration of a battery obtained by the battery manufacturing method according to the fourth embodiment. [Figure 6] FIG. 6 is a graph showing the X-ray diffraction patterns of the solid electrolytes according to Examples 1 to 3 and Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0009] (Findings that formed the basis of this disclosure) In the field of secondary batteries, where high energy density and large capacity are required, organic electrolytes, which consist of electrolyte salts dissolved in organic solvents, have traditionally been used. However, secondary batteries using organic electrolytes have been known to have concerns about leakage and the possibility of increased heat generation in the event of a short circuit.

[0010] Meanwhile, all-solid-state secondary batteries, which use inorganic solid electrolytes instead of organic electrolytes, are gaining attention. All-solid-state secondary batteries do not leak. Because inorganic solid electrolytes are non-flammable, they are expected to suppress heat generation in the event of a short circuit.

[0011] Known inorganic solid electrolytes for use in all-solid-state secondary batteries include sulfide solid electrolytes containing sulfur as a primary component and oxide solid electrolytes containing metal oxides as a primary component. Oxyhalide solid electrolytes, which are sulfur-free and have relatively high ionic conductivity, are expected to offer a safer solid electrolyte. An oxyhalide solid electrolyte refers to a solid electrolyte containing oxygen and halogen elements.

[0012] In the manufacture of all-solid-state secondary batteries, positive electrodes are manufactured, for example, by a coating method. In the coating method, for example, a slurry containing a positive electrode active material, a solid electrolyte, and a solvent is applied to a current collector to form a coating film, and the coating film is then dried to manufacture a positive electrode. The present inventors have newly discovered that when a positive electrode is manufactured by a coating method using an oxyhalide solid electrolyte, the resistance of the resulting positive electrode may increase. They have also found that batteries using such positive electrodes do not achieve sufficient charge / discharge efficiency. Therefore, the present inventors have conducted extensive research on positive electrodes manufactured by a coating method using an oxyhalide solid electrolyte and have discovered a new positive electrode material that can be used to manufacture positive electrodes with reduced resistance increase.

[0013] (Summary of one aspect of the present disclosure) The positive electrode material according to the first embodiment of the present disclosure is a positive electrode active material; a solid electrolyte; an organic solvent; Including, the solid electrolyte comprises Li, M, O, and X; M is at least one selected from the group consisting of Ta and Nb, X is at least one selected from the group consisting of F, Cl, Br, and I; The organic solvent has a boiling point of 212°C or less.

[0014] The positive electrode material according to the first embodiment can produce a positive electrode with a suppressed increase in resistance. When a positive electrode is produced by a coating method using an oxyhalide solid electrolyte, the reason for the increased resistance of the resulting positive electrode is not entirely clear. However, one possible cause is thought to be, for example, a decrease in electronic conductivity and ionic conductivity due to residual solvent, which increases the resistance. The positive electrode material according to the first embodiment can produce a positive electrode with reduced residual solvent, which is thought to suppress an increase in the resistance of the positive electrode. Thus, in a battery equipped with a positive electrode produced using the positive electrode material according to the first embodiment, an increase in internal resistance is suppressed, thereby improving charge / discharge efficiency. In other words, the positive electrode material according to the first embodiment is suitable for producing a positive electrode that can improve the charge / discharge efficiency of the battery.

[0015] In the second aspect of the present disclosure, for example, in the positive electrode material according to the first aspect, the organic solvent may have a boiling point of 208° C. or less.

[0016] The positive electrode material according to the second embodiment is suitable for producing a positive electrode that can further improve the charge / discharge efficiency of a battery.

[0017] In a third aspect of the present disclosure, for example, in the positive electrode material according to the first or second aspect, X may include Cl.

[0018] The positive electrode material according to the third embodiment is suitable for producing a positive electrode that can further improve the charge / discharge efficiency of a battery.

[0019] In a fourth aspect of the present disclosure, for example, in the positive electrode material according to any one of the first to third aspects, the solid electrolyte may include a crystalline phase in which at least one peak exists in a diffraction angle 2θ range of 11.05° or more and 13.86° or less in an X-ray diffraction pattern obtained by X-ray diffraction measurement using Cu-Kα radiation as a radiation source.

[0020] In the positive electrode material according to the fourth aspect, the solid electrolyte contains the above-described crystalline phase, which facilitates the formation of paths for lithium ion diffusion in the solid electrolyte. Therefore, the positive electrode material according to the fourth aspect contains a solid electrolyte with improved lithium ion conductivity. This allows a positive electrode manufactured using the positive electrode material according to the fourth aspect to further improve the charge / discharge efficiency of a battery.

[0021] In a fifth aspect of the present disclosure, for example, in the positive electrode material according to any one of the first to fourth aspects, in the solid electrolyte, a molar ratio O / X of O to X may be 0.16 or more and 0.35 or less.

[0022] In the positive electrode material according to the fifth aspect, when the molar ratio O / X of the solid electrolyte satisfies the above range, a highly conductive crystalline phase is easily realized in the solid electrolyte. Therefore, the lithium ion conductivity of the solid electrolyte contained in the positive electrode material is further improved. As a result, a positive electrode manufactured using the positive electrode material according to the sixth aspect can further improve the charge / discharge efficiency of the battery.

[0023] In a sixth aspect of the present disclosure, for example, in the positive electrode material according to any one of the first to fifth aspects, the molar ratio Li / M of Li to M in the solid electrolyte may be 0.60 or more and 2.4 or less.

[0024] In the positive electrode material according to the sixth aspect, when the molar ratio Li / M of the solid electrolyte satisfies the above range, the Li concentration, which acts as a conductive carrier in the solid electrolyte, can be optimized. This further improves the lithium ion conductivity of the solid electrolyte contained in the positive electrode material. As a result, a positive electrode manufactured using the positive electrode material according to the sixth aspect can further improve the charge / discharge efficiency of a battery.

[0025] In the seventh aspect of the present disclosure, for example, in the positive electrode material according to the sixth aspect, the molar ratio Li / M may be 0.96 or more and 1.20 or less.

[0026] In the positive electrode material according to the seventh aspect, when the molar ratio Li / M of the solid electrolyte satisfies the above range, the lithium ion conductivity of the solid electrolyte is further improved, and thus a positive electrode manufactured using the positive electrode material according to the seventh aspect can further improve the charge / discharge efficiency of a battery.

[0027] In an eighth aspect of the present disclosure, for example, in the positive electrode material according to any one of the first to seventh aspects, the organic solvent may include at least one selected from the group consisting of a compound having a halogen group and a hydrocarbon.

[0028] The organic solvent containing at least one selected from the group consisting of halogen-containing compounds and hydrocarbons is suitable as a solvent for the positive electrode material, and therefore the positive electrode material according to the eighth embodiment is suitable for producing a positive electrode that can further improve the charge / discharge efficiency of a battery.

[0029] In the ninth aspect of the present disclosure, for example, in the positive electrode material according to the eighth aspect, the compound having a halogen group may have only a halogen group as a functional group.

[0030] A compound having only a halogen group as a functional group can easily disperse an oxyhalide solid electrolyte (i.e., a solid electrolyte containing O and X). Therefore, the positive electrode material according to the ninth embodiment is suitable for producing a positive electrode that can further improve the charge / discharge efficiency of a battery.

[0031] In a tenth aspect of the present disclosure, for example, in the positive electrode material according to any one of the first to ninth aspects, the organic solvent may contain an aromatic compound.

[0032] The organic solvent containing the aromatic compound is suitable as a solvent for the positive electrode material, and therefore the positive electrode material according to the tenth aspect is suitable for producing a positive electrode that can further improve the charge / discharge efficiency of the battery.

[0033] In an eleventh aspect of the present disclosure, for example, in the positive electrode material according to any one of the first to tenth aspects, the organic solvent may include at least one selected from the group consisting of tetralin, mesitylene, xylene, cumene, pseudocumene, ethylbenzene, chlorobenzene, 2,4-dichlorobenzene, o-chlorotoluene, 1,3-dichlorobenzene, p-chlorotoluene, 1,2-dichlorobenzene, 1,4-dichlorobutane, 2,4-dichlorotoluene, and 3,4-dichlorotoluene.

[0034] The compound that can be used as the organic solvent for the positive electrode material according to the eleventh embodiment can easily disperse an oxyhalide solid electrolyte, and therefore the positive electrode material according to the eleventh embodiment is suitable for producing a positive electrode that can further improve the charge / discharge efficiency of a battery.

[0035] In a twelfth aspect of the present disclosure, for example, in the positive electrode material according to the eleventh aspect, the organic solvent may include at least one selected from the group consisting of tetralin, mesitylene, and xylene.

[0036] The compound that can be used as the organic solvent of the positive electrode material according to the twelfth embodiment can more easily disperse the oxyhalide solid electrolyte, and therefore the positive electrode material according to the twelfth embodiment is suitable for producing a positive electrode that can further improve the charge / discharge efficiency of a battery.

[0037] In a thirteenth aspect of the present disclosure, for example, in the positive electrode material according to any one of the first to twelfth aspects, the organic solvent may have a polarity term δp in Hansen solubility parameters of 4.3 or less.

[0038] Organic solvents with a polarity term δp of 4.3 or less in the Hansen solubility parameter have low reactivity at the interface with other materials. Therefore, in the positive electrode material according to the thirteenth aspect of the present disclosure, the reaction at the interface between the organic solvent and other materials is suppressed, enabling low resistance. Therefore, the positive electrode material according to the thirteenth aspect is suitable for producing a positive electrode that can further improve the charge / discharge efficiency of a battery.

[0039] A method for producing a positive electrode according to a fourteenth aspect of the present disclosure includes the steps of: removing the organic solvent from the cathode material according to any one of the first to thirteenth aspects; Includes.

[0040] According to the manufacturing method of the fourteenth aspect, a positive electrode in which an increase in resistance is suppressed can be obtained. Therefore, the positive electrode obtained by the manufacturing method of the fourteenth aspect can suppress an increase in the internal resistance of the battery and improve the charge / discharge efficiency. Furthermore, according to the manufacturing method of the fourteenth aspect, a homogeneous positive electrode with reduced performance variation can be obtained.

[0041] A method for producing a positive electrode plate according to a fifteenth aspect of the present disclosure includes: Applying the positive electrode material according to any one of the first to thirteenth aspects onto a current collector; removing the organic solvent from the positive electrode material coated on the current collector; Includes.

[0042] According to the manufacturing method of the fifteenth aspect, a positive electrode plate with a suppressed increase in resistance can be obtained. Therefore, the positive electrode plate obtained by the manufacturing method of the fifteenth aspect can suppress an increase in the internal resistance of the battery and improve charge / discharge efficiency. Furthermore, according to the manufacturing method of the fifteenth aspect, a positive electrode plate with a homogeneous quality and reduced performance variation can be obtained.

[0043] A method for manufacturing a battery according to a sixteenth aspect of the present disclosure is a method for manufacturing a battery including a positive electrode, a negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode, obtaining the positive electrode by removing the organic solvent from the positive electrode material according to any one of the first to thirteenth aspects; Includes.

[0044] According to the manufacturing method of the sixteenth aspect, a battery with improved charge / discharge efficiency can be obtained.

[0045] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings, but the present disclosure is not limited to the following embodiments.

[0046] (Embodiment 1) The positive electrode material according to the first embodiment will be described below.

[0047] FIG. 1 is a schematic diagram showing a positive electrode material according to the first embodiment.

[0048] The positive electrode material 1000 according to the first embodiment includes a positive electrode active material 110, a solid electrolyte 100, and an organic solvent 111. The solid electrolyte 100 includes Li, M, O, and X. Here, M is at least one selected from the group consisting of Ta and Nb, and X is at least one selected from the group consisting of F, Cl, Br, and I. That is, the positive electrode material 1000 includes an oxyhalide solid electrolyte containing an oxygen element and a halogen element. The organic solvent 111 has a boiling point of 212°C or less.

[0049] According to the above configuration, it is possible to provide a cathode material 1000 suitable for manufacturing a cathode capable of improving the charge / discharge efficiency of a battery. Specifically, by using the cathode material 1000, it is possible to manufacture a cathode in which an increase in resistance is suppressed. Therefore, in a battery equipped with a cathode manufactured using the cathode material 1000, an increase in internal resistance is suppressed, and thus the charge / discharge efficiency is improved.

[0050] The positive electrode material 1000 may be in the form of a paste or a dispersion liquid. In the positive electrode material 1000, the solid electrolyte 100 and the positive electrode active material 110 are, for example, particles. In the positive electrode material 1000, the solid electrolyte 100 and the positive electrode active material 110 are mixed with an organic solvent 111. The viscosity of the positive electrode material 1000 can be adjusted as appropriate. For example, when the positive electrode material 1000 is applied by a method such as a spray method, the viscosity of the positive electrode material 1000 is relatively low. When the positive electrode material 1000 is applied by a method such as a doctor blade method, the viscosity of the positive electrode material 1000 is relatively high.

[0051] The ratio of the combined mass of the solid electrolyte 100 and the positive electrode active material 110 to the combined mass of the solid electrolyte 100, the positive electrode active material 110, and the organic solvent 111 is not particularly limited and may be, for example, 80 mass % or less. With this configuration, the positive electrode material 1000 can be easily applied to the surface of the current collector.

[0052] (Cathode active material) The positive electrode active material 110 includes a material capable of absorbing and releasing metal ions (e.g., lithium ions). Examples of the positive electrode active material 110 include lithium-containing transition metal oxides, transition metal fluorides, polyanion materials, fluorinated polyanion materials, transition metal sulfides, transition metal oxysulfides, and transition metal oxynitrides. Examples of lithium-containing transition metal oxides include Li(Ni,Co,Al)O2, Li(Ni,Co,Mn)O2, and LiCoO2. In particular, when a lithium-containing transition metal oxide is used as the positive electrode active material 110, the manufacturing cost of the positive electrode can be reduced and the average discharge voltage can be increased.

[0053] The positive electrode active material 110 may include Ni, Co, and Mn. The positive electrode active material 110 may include lithium nickel cobalt manganese oxide. For example, the positive electrode active material 110 may include Li(Ni,Co,Al)O.

[0054] According to the above configuration, the positive electrode material 1000 can further increase the energy density and charge / discharge efficiency of a battery equipped with a positive electrode manufactured using the positive electrode material 1000.

[0055] At least a portion of the surface of the positive electrode active material 110 may be covered with a coating material different from the positive electrode active material 110 .

[0056] Coating materials include Li-Nb-O compounds such as LiNbO3, Li-BO compounds such as LiBO2 and Li3BO3, Li-Al-O compounds such as LiAlO2, Li-Si-O compounds such as Li4SiO4, Li2SO4, and Li4Ti5O. 12Li-Ti-O compounds such as Li2ZrO3, Li-Zr-O compounds such as Li2MoO3, Li-VO compounds such as LiV2O5, Li-WO compounds such as Li2WO4, or Li-PO compounds such as Li3PO4.

[0057] By including the positive electrode active material 110 having the above configuration, oxidation of the solid electrolyte 100 can be suppressed in the positive electrode produced using the positive electrode material 1000.

[0058] At least a portion of the surface of the positive electrode active material 110 may be covered with an oxyhalide solid electrolyte. By including the positive electrode active material 110 having the above configuration, the positive electrode material 1000 can reduce the interfacial resistance in a positive electrode manufactured using the positive electrode material 1000.

[0059] The median diameter of the positive electrode active material 110 may be 0.1 μm or more and 100 μm or less. When the median diameter of the positive electrode active material is 0.1 μm or more, the positive electrode active material 110 and the solid electrolyte 100 can be well dispersed in the positive electrode material 1000. Therefore, a battery including a positive electrode manufactured using the positive electrode material 1000 can have improved charge / discharge characteristics. When the median diameter of the positive electrode active material 110 is 100 μm or less, the lithium diffusion rate within the positive electrode active material is increased. Therefore, a battery including a positive electrode manufactured using the positive electrode material 1000 can operate at high power.

[0060] In this specification, the median diameter of the positive electrode active material 110 refers to the particle size (d50) corresponding to 50% cumulative volume, determined from the particle size distribution measured on a volume basis by a laser diffraction scattering method. The particle size distribution can also be measured using, for example, an image analyzer. The same applies to the median diameters of other materials.

[0061] (solid electrolyte) The solid electrolyte 100 contains Li, M, O, and X, where X is at least one selected from the group consisting of F, Cl, Br, and I. That is, the positive electrode material 1000 contains an oxyhalide solid electrolyte. The oxyhalide solid electrolyte may have, for example, lithium ion conductivity.

[0062] In the solid electrolyte 100, X may contain Cl. X1 may be Cl. By containing Cl, the solid electrolyte 100 can have high ionic conductivity. Therefore, by containing a solid electrolyte containing Cl, the positive electrode material 1000 can further improve the charge / discharge efficiency of a battery equipped with a positive electrode manufactured using the positive electrode material 1000. In other words, the above configuration provides a positive electrode material 1000 suitable for manufacturing a positive electrode that can further improve the charge / discharge efficiency of a battery. X may contain Cl and at least one selected from the group consisting of F, Br, and I.

[0063] In the solid electrolyte 100, M is at least one selected from the group consisting of Ta and Nb. By including at least one selected from the group consisting of Ta and Nb, the solid electrolyte 100 can have high ionic conductivity. Therefore, by including the solid electrolyte 100 having such a configuration, the positive electrode material 1000 can be used to produce a positive electrode having high lithium ion conductivity. Therefore, with the above configuration, the positive electrode material 1000 suitable for producing a positive electrode that can further improve the charge / discharge efficiency of a battery can be obtained.

[0064] More specifically, the solid electrolyte 100 may contain at least one selected from the group consisting of a material containing Li, Ta, O, and Cl, a material containing Li, Nb, O, and Cl, and a material containing Li, Ta, Nb, O, and Cl. The solid electrolyte 100 may be a material containing Li, Ta, O, and Cl, a material containing Li, Nb, O, and Cl, or a material containing Li, Ta, Nb, O, and Cl. The solid electrolyte 100 does not have to contain sulfur.

[0065] In the solid electrolyte 100, the molar ratio O / X of O to X may be 0.16 or more and 0.35 or less. For example, when X is Cl, the molar ratio O / Cl of O to Cl may be 0.16 or more and 0.35 or less. When X includes multiple halogen elements, the number of moles of X is the total number of moles of the multiple halogen elements. When the molar ratio O / X of the solid electrolyte 100 satisfies the above range, a high conductivity crystalline phase is easily realized in the solid electrolyte 100. Therefore, the lithium ion conductivity of the solid electrolyte 100 contained in the positive electrode material 1000 is further improved. As a result, a positive electrode manufactured using the positive electrode material 1000 can further improve the charge / discharge efficiency of a battery.

[0066] In the solid electrolyte 100, the molar ratio Li / M of Li to M may be 0.60 or more and 2.4 or less. That is, the ratio Li / (Ta+Nb), which is the ratio of the number of moles of Li to the total number of moles of Ta and Nb, may be 0.6 or more and 2.4 or less. When the molar ratio Li / M of the solid electrolyte 100 satisfies the above range, the concentration of Li, which serves as a conductive carrier in the solid electrolyte 100, can be optimized. This further improves the lithium ion conductivity of the solid electrolyte 100 contained in the positive electrode material 1000. As a result, a positive electrode manufactured using the positive electrode material 1000 can further improve the charge / discharge efficiency of a battery.

[0067] In the solid electrolyte 100, the molar ratio Li / M of Li to M may be 0.96 or more and 1.20 or less. That is, the ratio Li / (Ta+Nb), which is the ratio of the number of moles of Li to the total number of moles of Ta and Nb, may be 0.96 or more and 1.20 or less. When the molar ratio Li / M of the solid electrolyte 100 satisfies the above range, the concentration of Li, which serves as a conductive carrier in the solid electrolyte 100, can be further optimized. This further improves the lithium ion conductivity of the solid electrolyte 100 contained in the positive electrode material 1000. As a result, a positive electrode manufactured using the positive electrode material 1000 can further improve the charge / discharge efficiency of a battery.

[0068] The solid electrolyte 100 may contain a crystalline phase in which at least one peak exists in the diffraction angle 2θ range of 11.05° or more and 13.86° or less in an X-ray diffraction pattern obtained by X-ray diffraction measurement using Cu-Kα radiation as a radiation source. When the solid electrolyte 100 contains such a crystalline phase, a path for lithium ion diffusion in the solid electrolyte 100 is easily formed. Therefore, by including the solid electrolyte 100 containing such a crystalline phase, a positive electrode material 1000 having high lithium ion conductivity can be manufactured. In other words, a positive electrode manufactured using the positive electrode material 1000 can further improve the charge / discharge efficiency of a battery.

[0069] The shape of the solid electrolyte 100 is not particularly limited. When the solid electrolyte 100 is a powder, its shape may be, for example, needle-like, spherical, oval-spherical, etc. For example, the shape of the solid electrolyte 100 may be particulate.

[0070] For example, when the solid electrolyte 100 is particulate (e.g., spherical), the median diameter of the solid electrolyte 100 may be 100 μm or less. When the median diameter is 100 μm or less, the solid electrolyte 100 can be well dispersed in the positive electrode material 1000. Therefore, a positive electrode manufactured using the positive electrode material 1000 can further improve the charge / discharge efficiency of a battery.

[0071] The median diameter of the solid electrolyte 100 may be 10 μm or less. When the median diameter is 10 μm or less, the solid electrolyte 100 can be well dispersed in the positive electrode material 1000. Therefore, a positive electrode manufactured using the positive electrode material 1000 can further improve the charge / discharge efficiency of a battery.

[0072] The median diameter of the solid electrolyte 100 may be smaller than the median diameter of the positive electrode active material 110. This allows the positive electrode active material 110 and the solid electrolyte 100 to be well dispersed in the positive electrode material 1000.

[0073] (organic solvent) As described above, the organic solvent 111 has a boiling point of 212°C or lower. By including such an organic solvent 111, the cathode material 1000 can produce a cathode with reduced residual solvent. In the cathode obtained in this manner, an increase in resistance due to the residual solvent is suppressed. Therefore, the cathode material 1000 is suitable for producing a cathode that can improve the charge / discharge efficiency of a battery. In this specification, the "boiling point" refers to the temperature at which the saturated vapor pressure of the liquid becomes equal to 1 atmosphere.

[0074] The organic solvent 111 may have a boiling point of 208°C or lower. By including such an organic solvent 111, the positive electrode material 1000 can produce a positive electrode with a reduced amount of residual solvent. In the positive electrode obtained in this manner, an increase in resistance due to the residual solvent is further suppressed. Therefore, the positive electrode material 1000 including the organic solvent 111 having such a boiling point is suitable for producing a positive electrode that can further improve the charge / discharge efficiency of a battery.

[0075] The organic solvent 111 may contain at least one selected from the group consisting of compounds having a halogen group and hydrocarbons. These are suitable as a solvent for the positive electrode material 1000. Therefore, the positive electrode material 1000 containing such a solvent is suitable for producing a positive electrode that can further improve the charge / discharge efficiency of a battery.

[0076] A hydrocarbon is a compound consisting only of carbon and hydrogen. The hydrocarbon may be an aliphatic hydrocarbon. The hydrocarbon may be a saturated hydrocarbon or an unsaturated hydrocarbon. The hydrocarbon may be a linear or branched chain. The number of carbon atoms contained in the hydrocarbon is not particularly limited and may be 7 or more. By using a hydrocarbon, a positive electrode material 1000 with excellent dispersibility can be obtained.

[0077] The hydrocarbon may have a ring structure. The ring structure may be an alicyclic hydrocarbon or an aromatic hydrocarbon. The ring structure may be a monocyclic or a polycyclic hydrocarbon. When the hydrocarbon has a ring structure, the solid electrolyte 100 can be easily dispersed in the organic solvent 111. From the viewpoint of improving the dispersibility of the solid electrolyte 100 in the positive electrode material 1000, the hydrocarbon may contain an aromatic hydrocarbon. The hydrocarbon may be an aromatic hydrocarbon.

[0078] The compound having a halogen group may be composed only of carbon and hydrogen, except for the halogen group. In other words, a compound having a halogen group refers to a compound in which at least one hydrogen atom contained in a hydrocarbon is substituted with a halogen group. Examples of halogen groups include F, Cl, Br, and I. The halogen group may be at least one selected from the group consisting of F, Cl, Br, and I, or multiple types may be used. The compound having a halogen group may have high polarity. By using a compound having a halogen group as the organic solvent 111, the dispersibility of the solid electrolyte 100 in the positive electrode material 1000 can be improved. As a result, the positive electrode material 1000 can form a denser positive electrode.

[0079] The number of carbon atoms contained in the compound having a halogen group is not particularly limited and may be 7 or more. This makes the compound having a halogen group less likely to volatilize, allowing for stable production of the positive electrode material 1000. Furthermore, the compound having a halogen group may have a large molecular weight. In other words, the compound having a halogen group may have a high boiling point.

[0080] The compound having a halogen group may have only a halogen group as a functional group. In this case, the number of halogens contained in the compound having a halogen group is not particularly limited. At least one halogen selected from the group consisting of F, Cl, Br, and I may be used as the halogen, or multiple halogens may be used. By using such a compound as the organic solvent 111, the solid electrolyte can be easily dispersed, thereby obtaining a positive electrode material 1000 with excellent dispersibility. As a result, the positive electrode material 1000 can form a denser positive electrode. By using such a compound as the organic solvent 111, the positive electrode material 1000 can easily form a dense positive electrode with fewer pinholes, irregularities, etc.

[0081] The compound having a halogen group may be a halogenated hydrocarbon. A halogenated hydrocarbon refers to a compound in which all hydrogen atoms contained in a hydrocarbon are substituted with halogen groups. By using a halogenated hydrocarbon as the organic solvent 111, the solid electrolyte 100 can be easily dispersed, thereby obtaining a cathode material 1000 with excellent dispersibility. As a result, the cathode material 1000 can form a denser cathode. By using a halogenated hydrocarbon as the organic solvent 111, the cathode material 1000 can easily form a dense cathode with fewer pinholes, irregularities, and the like.

[0082] The organic solvent 111 may include, for example, an aromatic compound.

[0083] The organic solvent 111 may include at least one selected from the group consisting of, for example, tetralin, mesitylene, xylene, cumene, pseudocumene, ethylbenzene, chlorobenzene, 2,4-dichlorobenzene, o-chlorotoluene, 1,3-dichlorobenzene, p-chlorotoluene, 1,2-dichlorobenzene, 1,4-dichlorobutane, 2,4-dichlorotoluene, and 3,4-dichlorotoluene. These compounds can easily disperse the oxyhalide solid electrolyte. Therefore, by using these compounds as the organic solvent 111, the positive electrode material 1000 can form a denser positive electrode. Such a positive electrode can further improve the charge / discharge efficiency of the battery.

[0084] The organic solvent 111 may include, for example, at least one selected from the group consisting of tetralin, mesitylene, and xylene. These compounds can more easily disperse the oxyhalide solid electrolyte. Therefore, by using these compounds as the organic solvent 111, the cathode material 1000 can form a denser cathode. Such a cathode can further improve the charge / discharge efficiency of the battery.

[0085] The number of halogen groups contained in the compound having a halogen group is not particularly limited, and may be, for example, one.

[0086] The lower limit of the boiling point of the organic solvent 111 may be, for example, 100°C or higher from the viewpoint of the stability of the positive electrode material 1000. The organic solvent 111 may be liquid at room temperature (25°C). Such an organic solvent 111 is unlikely to volatilize at room temperature, allowing the positive electrode material 1000 to be stably produced. This results in a positive electrode material that can be easily applied to the surface of an electrode or current collector. This also allows the organic solvent 111 to be easily removed by drying. The organic solvent 111 may be a liquid that can disperse an oxyhalide solid electrolyte. The organic solvent 111 does not need to dissolve the oxyhalide solid electrolyte.

[0087] The organic solvent 111 may have a polarity term δp of 4.3 or less in the Hansen solubility parameters. The organic solvent 111 having a polarity term δp of 4.3 or less in the Hansen solubility parameters has low reactivity at the interface with other materials, i.e., the solid electrolyte 100 and the positive electrode active material 110. Therefore, in the positive electrode material 1000, the reaction at the interface between the organic solvent 111 and other materials is suppressed, thereby enabling low resistance. Therefore, the positive electrode material 1000 containing the organic solvent 111 that satisfies the above Hansen solubility parameters is suitable for producing a positive electrode that can further improve the charge / discharge efficiency of a battery.

[0088] (Other ingredients) The positive electrode material 1000 may contain a binder to improve the adhesion between particles. The binder is used to improve the binding properties of the materials that make up the electrode. Examples of binders include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polymethyl acrylate, polyethyl acrylate, polyhexyl acrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyhexyl methacrylate, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropolypropylene, styrene-butadiene rubber, and carboxymethyl cellulose. The binder may be a copolymer of two or more materials selected from the group consisting of tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, and hexadiene, or a mixture of two or more materials selected from these.

[0089] The positive electrode material 1000 may contain a conductive additive to enhance electronic conductivity. Examples of conductive additives that can be used include graphites (natural graphite and artificial graphite), carbon blacks (acetylene black, ketjen black, etc.), conductive fibers (carbon fiber, metal fiber, etc.), metal powders (carbon fluoride, aluminum, etc.), conductive whiskers (zinc oxide, potassium titanate, etc.), conductive metal oxides (titanium oxide, etc.), and conductive polymer compounds (polyaniline, polypyrrole, polythiophene, etc.). Using a carbon conductive additive as the conductive additive can reduce costs.

[0090] The positive electrode material 1000 may contain a dispersant for the purpose of improving the dispersibility of the solid electrolyte 100 or the positive electrode active material 110 .

[0091] (Embodiment 2) The following describes a method for producing a positive electrode according to embodiment 2. Details that overlap with embodiment 1 will be omitted where appropriate.

[0092] 2 is a flowchart showing an example of a method for manufacturing a positive electrode according to embodiment 2. The method for manufacturing a positive electrode according to embodiment 2 includes step S1001 of removing organic solvent 111 from positive electrode material 1000 according to embodiment 1. That is, the positive electrode is a member including solid electrolyte 100 and positive electrode active material 110.

[0093] For example, a homogeneous positive electrode can be produced by removing the organic solvent 111 from the positive electrode material 1000 containing the solid electrolyte 100, the positive electrode active material 110, and the organic solvent 111. Furthermore, as described in the first embodiment, the positive electrode material 1000 can produce a positive electrode with a reduced amount of residual solvent. Therefore, in a positive electrode produced by the production method according to the second embodiment, an increase in resistance due to the residual solvent is suppressed. Therefore, in a battery including such a positive electrode, an increase in internal resistance is suppressed, thereby improving charge / discharge efficiency. That is, the positive electrode obtained by the production method according to the second embodiment can suppress an increase in the internal resistance of the battery and improve charge / discharge efficiency.

[0094] In step S1001, the organic solvent 111 is removed from the positive electrode material 1000. At this time, the organic solvent 111 may be removed by, for example, drying at normal pressure. Removal of the organic solvent 111 by drying at normal pressure refers to removing the organic solvent 111 from the positive electrode material 1000 in an atmospheric pressure atmosphere. In the drying at normal pressure, the positive electrode material 1000 may be heated to, for example, 100°C or higher and 200°C or lower.

[0095] In step S1001, the organic solvent 111 may be removed from the positive electrode material 1000 by, for example, drying under reduced pressure. The positive electrode material 1000 before removing the organic solvent 111 has fluidity. Therefore, the positive electrode material 1000 has excellent formability and can form, for example, a coating film having a uniform thickness. By drying such a coating film, for example, a dense positive electrode with few pinholes, irregularities, etc. can be easily obtained.

[0096] Removal of the organic solvent 111 by drying under reduced pressure means removing the organic solvent 111 from the positive electrode material 1000 in a pressure atmosphere lower than atmospheric pressure. The pressure atmosphere lower than atmospheric pressure is, for example, −0.01 MPa or lower in gauge pressure. During the drying under reduced pressure, the positive electrode material 1000 may be heated to, for example, 100° C. or higher and 200° C. or lower.

[0097] The organic solvent 111 may be removed from the positive electrode material 1000 by vacuum drying. Removal of the organic solvent 111 by vacuum drying refers to removing the organic solvent 111 from the positive electrode material 1000 at a pressure equal to or lower than the vapor pressure at a temperature 20° C. lower than the boiling point of the organic solvent 111, for example.

[0098] The removal of the organic solvent 111 can be confirmed by, for example, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), gas chromatography (GC), or gas chromatography mass spectrometry (GC / MS). Note that the organic solvent 111 does not need to be completely removed as long as the positive electrode obtained after drying has ionic conductivity.

[0099] (Embodiment 3) The following describes a method for manufacturing a positive electrode plate according to embodiment 3. Content that overlaps with embodiments 1 and 2 will be omitted as appropriate.

[0100] 3 is a flowchart showing an example of a method for manufacturing a positive electrode plate according to embodiment 3. The method for manufacturing a positive electrode plate according to embodiment 3 includes step S2001 of applying the positive electrode material 1000 according to embodiment 1 described above onto a current collector, and step S2002 of removing organic solvent 111 from the positive electrode material 1000 applied onto the current collector.

[0101] 4 is a cross-sectional view showing a schematic configuration of a positive electrode plate obtained by the manufacturing method of a positive electrode plate according to embodiment 3. As shown in FIG. 4, a positive electrode plate 2000 includes a positive electrode 201 and a current collector 202. The positive electrode 201 includes a positive electrode active material 110 and a solid electrolyte 100.

[0102] In the manufacturing method according to the third embodiment, in step S2001, for example, the positive electrode material 1000 is applied onto a current collector 202 serving as a substrate to form a film of the positive electrode material 1000. In step S2002, the organic solvent 111 is removed from the film of the positive electrode material 1000, thereby producing, for example, a homogeneous positive electrode 201.

[0103] The material used for the current collector 202 may be any material that has electronic conductivity, and examples thereof include metals, semimetals, and alloys that are mixtures thereof.

[0104] Specific examples include carbon (C), silicon (Si), bismuth (Bi), antimony (Sb), lead (Pb), tin (Sn), iron (Fe), chromium (Cr), zinc (Zn), tantalum (Ta), nickel (Ni), cobalt (Co), cadmium (Cd), manganese (Mn), zirconium (Zr), titanium (Ti), aluminum (Al), beryllium (Be), thorium (Th), magnesium (Mg), sodium (Na), calcium (Ca), strontium (Sr), barium (Ba), potassium (K), rubidium (Rb), cesium (Cs), lithium (Li), vanadium (V), tungsten (W), silver (Ag), gold (Au), and platinum (Pt). Among these, carbon (C), iron (Fe), nickel (Ni), aluminum (Al), and copper (Cu) are preferred. Alloys of the above metals may also be used.

[0105] An aluminum alloy may be used as the material for the current collector 202. As specified in the Japanese Industrial Standards (JIS H4000, etc.), examples of the aluminum alloy include pure aluminum such as A1050 (Al content of 99.50 wt% or more, Fe 0.40 wt% or less, Si 0.25 wt% or less, and Cu 0.05 wt% or less) and A1085 (Al content of 99.85 wt% or more, Fe 0.12 wt% or less, Si 0.1 wt% or less, and Cu 0.03 wt% or less), and strength-reinforced aluminum alloys such as A2017 (Al-3.5 to 4.5 wt% Cu alloy), A3003 (Al-1.0 to 1.5 wt% Mn-0.05 to 0.20 wt% Cu alloy), and A8021 (Al-1.5 wt% Fe-0.05 wt% Cu alloy). When the current collector 202 contains an aluminum alloy, it is lightweight and has high strength, making it possible to realize a battery that has both high energy density per unit weight and high durability.

[0106] The material used for the current collector 202 may be a polymer material mixed with the above-mentioned material having electron conductivity.

[0107] The current collector 202 may be configured such that the interior and surface thereof are made of different materials. That is, the current collector 202 may be configured such that the surface of the part constituting the interior is coated with the above-mentioned material having electron conductivity.

[0108] The shape of the current collector 202 is not limited, but in order to improve adhesion to the positive electrode 201, for example, a material with a large surface roughness may be used.

[0109] (Fourth embodiment) The following describes a method for manufacturing a battery according to embodiment 4. Content that overlaps with embodiments 1, 2, and 3 will be omitted where appropriate.

[0110] FIG. 5 is a cross-sectional view showing a schematic configuration of a battery obtained by the manufacturing method of the battery according to the fourth embodiment. As shown in FIG. 5, the battery 3000 obtained by the manufacturing method of the fourth embodiment includes a positive electrode 301, a negative electrode 303, and an electrolyte layer 302 located between the positive electrode 301 and the negative electrode 303. The positive electrode 301 includes a positive electrode active material 110 and a solid electrolyte 100. The manufacturing method of the battery according to the fourth embodiment includes a step of obtaining the positive electrode 301 by removing the organic solvent 111 from the positive electrode material 1000 according to the first embodiment. That is, in the manufacturing method of the battery according to the fourth embodiment, the manufacturing method of the positive electrode described in the second embodiment or the manufacturing method of the positive electrode plate described in the third embodiment may be used to manufacture the positive electrode 301.

[0111] In the battery manufacturing method according to the fourth embodiment, the positive electrode material 1000 described in the first embodiment is used to manufacture the positive electrode 301. Therefore, the positive electrode 301 obtained by the manufacturing method according to the fourth embodiment is a positive electrode with a reduced amount of residual solvent, and an increase in resistance is suppressed. Therefore, the manufacturing method according to the fourth embodiment can obtain a battery 3000 with improved charge / discharge efficiency.

[0112] The positive electrode 301 includes a positive electrode active material 110 and a solid electrolyte 100 .

[0113] The volume ratio "v1:100-v1" of the positive electrode active material 110 to the solid electrolyte 100 contained in the positive electrode 301 may satisfy 30≦v1≦98. Here, v1 represents the volume ratio of the positive electrode active material 110 when the total volume of the positive electrode active material 110 and the solid electrolyte 100 contained in the positive electrode 301 is taken as 100. When 30≦v1 is satisfied, a sufficient energy density of the battery 3000 can be ensured. When v1≦95 is satisfied, the battery 3000 can operate at high output.

[0114] The thickness of the positive electrode 301 may be 10 μm or more and 500 μm or less. When the thickness of the positive electrode 301 is 10 μm or more, the energy density of the battery 3000 is sufficiently ensured. When the thickness of the positive electrode 301 is 500 μm or less, the battery 3000 can operate at high power.

[0115] The electrolyte layer 302 is a layer containing an electrolyte.

[0116] The solid electrolyte contained in electrolyte layer 302 may be an oxyhalide solid electrolyte. The solid electrolyte contained in electrolyte layer 302 may be an oxyhalide solid electrolyte having the same composition as solid electrolyte 100 contained in cathode material 1000 in the first embodiment, or an oxyhalide solid electrolyte containing the same crystalline phase. With the above configuration, the power density and charge / discharge characteristics of battery 3000 can be further improved.

[0117] The solid electrolyte contained in the electrolyte layer 302 may be a halide solid electrolyte having a different composition or a different crystal phase from the oxyhalide solid electrolyte in the first embodiment.

[0118] The solid electrolyte contained in the electrolyte layer 302 may be a halide solid electrolyte. Here, a halide solid electrolyte refers to a solid electrolyte that contains a halogen element but does not contain sulfur. In addition, in this disclosure, a sulfur-free solid electrolyte refers to a solid electrolyte represented by a composition formula that does not contain sulfur. Therefore, a solid electrolyte containing a very small amount of sulfur component, for example, 0.1 mass % or less of sulfur, is included in the sulfur-free solid electrolyte. The halide solid electrolyte may further contain oxygen as an anion other than the halogen element.

[0119] The solid electrolyte included in the electrolyte layer 302 may be a sulfide solid electrolyte, an oxide solid electrolyte, a polymer solid electrolyte, or a complex hydride solid electrolyte.

[0120] When the solid electrolyte contained in the electrolyte layer 302 is a sulfide solid electrolyte, examples of the sulfide solid electrolyte include Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, Li2S-GeS2, and Li 3.25 Ge 0.25 P 0.75 S4, Li 10 GeP2S 12 These can be used in addition to LiX, Li2O, MO q , Li p MO q The element X in "LiX" is at least one element selected from the group consisting of F, Cl, Br, and I. q " and "Li p MO q "The element M is at least one element selected from the group consisting of P, Si, Ge, B, Al, Ga, In, Fe, and Zn. q " and "Li p MO q " p and q in this expression are independent natural numbers.

[0121] According to the above configuration, since the electrolyte layer 302 contains a sulfide solid electrolyte having excellent reduction stability, a low potential negative electrode material such as graphite or metallic lithium can be used, and the energy density of the battery 3000 can be improved.

[0122] When the solid electrolyte contained in the electrolyte layer 302 is an oxide solid electrolyte, examples of the oxide solid electrolyte include NASICON-type solid electrolytes represented by LiTi2(PO4)3 and its element substitution products, (LaLi)TiO3-based perovskite-type solid electrolytes, Li 14 ZnGeO 16 , Li4SiO4, LiGeO4 and their element-substituted LISICON-type solid electrolytes, Li7La3Zr2O 12 Garnet-type solid electrolytes, such as those typified by LiN and its element substitution products, LiN and its H-substituted products, LiPO4 and its N-substituted products, and glasses or glass ceramics based on Li-BO compounds such as LiBO2 and LiBO3, to which materials such as LiSO4 and LiCO3 have been added, can be used.

[0123] When the solid electrolyte contained in the electrolyte layer 302 is a polymer solid electrolyte, for example, a compound of a polymer compound and a lithium salt can be used as the polymer solid electrolyte. The polymer compound may have an ethylene oxide structure. By having an ethylene oxide structure, the polymer compound can contain a large amount of lithium salt. This can further increase ionic conductivity. Examples of the lithium salt that can be used include LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2F)2, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), and LiC(SO2CF3)3. As the lithium salt, one type of lithium salt selected from these may be used alone, or a mixture of two or more types of lithium salts selected from these may be used.

[0124] When the solid electrolyte contained in the electrolyte layer 302 is a complex hydride solid electrolyte, for example, LiBH4-LiI, LiBH4-P2S5, or the like can be used as the complex hydride solid electrolyte.

[0125] The electrolyte layer 302 may contain a solid electrolyte as a main component, i.e., the electrolyte layer 302 may contain, for example, 50% or more of the solid electrolyte in terms of mass ratio to the entire electrolyte layer 302 (i.e., 50 mass % or more).

[0126] According to the above configuration, the charge and discharge characteristics of the battery 3000 can be further improved.

[0127] The electrolyte layer 302 may contain a solid electrolyte in a mass ratio of 70% or more (ie, 70 mass % or more) relative to the entire electrolyte layer 302.

[0128] According to the above configuration, the charge / discharge characteristics of the battery 3000 can be further improved.

[0129] The electrolyte layer 302 contains a solid electrolyte as a main component, and may further contain unavoidable impurities, or starting materials, by-products, decomposition products, and the like used in synthesizing the solid electrolyte.

[0130] The electrolyte layer 302 may contain, for example, 100% solid electrolyte in terms of mass ratio to the entire electrolyte layer 302 (ie, 100 mass %), excluding unavoidable impurities.

[0131] According to the above configuration, the charge / discharge characteristics of the battery 3000 can be further improved.

[0132] As described above, the electrolyte layer 302 may be made of only a solid electrolyte.

[0133] The electrolyte layer 302 may contain two or more of the above-mentioned materials exemplified as the solid electrolyte contained in the electrolyte layer 302. For example, the electrolyte layer 302 may contain a halide solid electrolyte and a sulfide solid electrolyte.

[0134] The thickness of the electrolyte layer 302 may be 1 μm or more and 300 μm or less. When the thickness of the electrolyte layer 302 is 1 μm or more, the cathode 301 and the anode 303 are less likely to short-circuit. When the thickness of the electrolyte layer 302 is 300 μm or less, the battery 3000 can operate at high power.

[0135] The negative electrode 303 includes a material having the property of absorbing and releasing metal ions (for example, lithium ions), and includes, for example, a negative electrode active material.

[0136] The negative electrode active material may be a metal material, a carbon material, an oxide, a nitride, a tin compound, a silicon compound, or the like. The metal material may be a single metal. Alternatively, the metal material may be an alloy. Examples of the metal material include lithium metal and lithium alloys. Examples of the carbon material include natural graphite, coke, partially graphitized carbon, carbon fiber, spherical carbon, artificial graphite, and amorphous carbon. From the viewpoint of capacity density, silicon (Si), tin (Sn), silicon compounds, and tin compounds may be used.

[0137] The negative electrode 303 may contain a solid electrolyte. As the solid electrolyte, any of the materials exemplified above as the solid electrolyte contained in the electrolyte layer 302 may be used. With the above configuration, the lithium ion conductivity inside the negative electrode 303 is increased, and the battery 3000 can operate at a high output.

[0138] The median diameter of the particles of the negative electrode active material may be 0.1 μm or more and 100 μm or less. When the median diameter of the particles of the negative electrode active material is 0.1 μm or more, the negative electrode active material and the solid electrolyte can be well dispersed in the negative electrode. This improves the charge / discharge characteristics of the battery 3000. When the median diameter of the particles of the negative electrode active material is 100 μm or less, lithium diffusion within the negative electrode active material is accelerated. This allows the battery 3000 to operate at high power.

[0139] The median diameter of the particles of the negative electrode active material may be larger than the median diameter of the particles of the solid electrolyte contained in the negative electrode 303. This allows the particles of the negative electrode active material and the particles of the solid electrolyte to be well dispersed.

[0140] The volume ratio "v2:100-v2" of the negative electrode active material to the solid electrolyte contained in the negative electrode 303 may satisfy 30≦v2≦95. Here, v2 represents the volume ratio of the negative electrode active material when the total volume of the negative electrode active material and the solid electrolyte contained in the negative electrode 303 is taken as 100. When 30≦v2, a sufficient energy density of the battery 3000 can be ensured. When v2≦95, the battery 3000 can operate at high output.

[0141] The thickness of the negative electrode 303 may be 10 μm or more and 500 μm or less. When the thickness of the negative electrode 303 is 10 μm or more, a sufficient energy density of the battery 3000 can be ensured. When the thickness of the negative electrode 303 is 500 μm or less, the battery 3000 can operate at high power.

[0142] At least one of the positive electrode 301, the electrolyte layer 302, and the negative electrode 303 may contain a binder to improve adhesion between particles. The binder is used to improve the binding properties of the materials constituting the electrodes. Examples of binders include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polymethyl ester of acrylic acid, polyethyl ester of acrylic acid, polyhexyl ester of acrylic acid, polymethacrylic acid, polymethyl ester of methacrylic acid, polyethyl ester of methacrylic acid, polyhexyl ester of methacrylic acid, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropolypropylene, styrene-butadiene rubber, and carboxymethyl cellulose. The binder may be a copolymer of two or more materials selected from the group consisting of tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, and hexadiene, or a mixture of two or more materials selected from these.

[0143] At least one of the positive electrode 301 and the negative electrode 303 may contain a conductive additive to enhance electronic conductivity. Examples of conductive additives that can be used include graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black and ketjen black, conductive fibers such as carbon fiber and metal fiber, metal powders such as carbon fluoride and aluminum, conductive whiskers such as zinc oxide and potassium titanate, conductive metal oxides such as titanium oxide, and conductive polymer compounds such as polyaniline, polypyrrole, and polythiophene. Using a carbon conductive additive as the conductive additive can reduce costs.

[0144] At least one of the positive electrode 301, the electrolyte layer 302, and the negative electrode 303 may contain a dispersant to improve the dispersibility of each component.

[0145] The battery 3000 can be configured as a battery of various shapes, such as a coin type, a cylindrical type, a square type, a sheet type, a button type, a flat type, and a laminate type. [Example]

[0146] Hereinafter, the present disclosure will be described in detail using examples and comparative examples.

[0147] [Preparation of solid electrolyte] In an argon atmosphere, Li2O2 and TaCl5 were weighed as raw materials so that the molar ratio of Li2O2:TaCl5 was 1:2. Then, using a planetary ball mill (Fritsch, P-7 model), milling was performed for 12 hours at 600 rpm. Further processing was performed at 200°C for 3 hours to obtain the solid electrolytes of Examples 1 to 3 and Comparative Example 1, each containing a crystalline phase consisting of Li, Ta, O, and Cl. The X-ray diffraction patterns of the obtained solid electrolytes were measured using an X-ray diffractometer (Rigaku, MiniFlex600). The X-ray diffraction patterns were measured by the θ-2θ method using Cu-Kα radiation (wavelengths 1.5405 Å and 1.5444 Å) as the X-ray source. Figure 6 is a graph showing the X-ray diffraction patterns of the solid electrolytes of Examples 1 to 3 and Comparative Example 1. 6, the solid electrolytes of Examples 1 to 3 and Comparative Example 1 had a peak at a diffraction angle 2θ of 11.08°, i.e., at least one peak existed in the range of diffraction angle 2θ of 11.05° or more and 13.86° or less. Hereinafter, a solid electrolyte consisting of Li, Ta, O, and Cl will be referred to as LTOC.

[0148] [Preparation of positive electrode material] LTOC was used as the solid electrolyte, and nickel-cobalt lithium aluminum oxide (hereinafter referred to as NCA) was used as the positive electrode active material. LTOC, NCA, a conductive additive, and a binder were placed in a commercially available polypropylene container, and an organic solvent was added to the mixture, which was then stirred using an ultrasonic homogenizer. The amount of organic solvent was adjusted so that the solid content of the resulting positive electrode material was 76.5%. Carbon fiber (VGCF-H) was used as the conductive additive. SBR (styrene butadiene rubber) was used as the binder. VGCF is a registered trademark of Showa Denko K.K.

[0149] [Removal of organic solvents by drying] Aluminum foil (thickness: 15 μm) was used as the current collector. The positive electrode material was coated onto this current collector, and the collector was placed on a hot plate to remove the organic solvent in an argon atmosphere. The drying conditions were preliminary drying at 50°C for 30 minutes, followed by main drying at 110°C for 30 minutes. Removal of the organic solvent was confirmed visually. If it was determined visually that a positive electrode plate had been obtained, it was judged to have been "dried successfully."

[0150] [Battery construction] A 550 μm thick layer (approximately 80 mg) of sulfide solid electrolyte Li2S-P2S5 and a positive electrode plate were stacked in this order inside an insulating outer cylinder. The positive electrode plate was positioned so that the positive electrode of the positive electrode plate faced the sulfide solid electrolyte. The positive electrode plate was made by punching out a dried electrode plate to a diameter of 9.4 mm and stacking them.

[0151] Next, metallic Li was layered on the side of the solid electrolyte layer opposite to the side in contact with the positive electrode, and this was compressed at a pressure of 80 MPa to produce a laminate consisting of the positive electrode, electrolyte layer, and negative electrode.

[0152] Next, stainless steel current collectors were placed on the top and bottom of the laminate, and current collecting leads were attached to the current collectors.

[0153] Finally, an insulating ferrule was used to isolate and seal the inside of the insulating outer cylinder from the outside atmosphere.

[0154] In this manner, the batteries of Examples 1 to 3 and Comparative Example 1 were fabricated.

[0155] [Charge / discharge test] The battery was placed in a thermostatic chamber at 25°C.

[0156] The battery was charged at a constant current of 0.05C (20-hour rate) to the theoretical capacity, with the end-of-charge voltage set to 4.3V (vs. Li).

[0157] Next, the battery was discharged at a current value similar to that of the 0.05 C rate. The discharge termination voltage was set to 2.5 V (vs. Li).

[0158] The initial charge-discharge efficiencies of the batteries of Examples 1 to 3 and Comparative Example 1 are shown in Table 1.

[0159] Example 1 Xylene, which has a boiling point of 140°C, was used as the organic solvent. The polarity term δp in the Hansen solubility parameter of xylene is 1.0. The positive electrode material was prepared using the method described above and dried in an argon atmosphere using the method described above. A battery was fabricated using this and a charge / discharge test was performed.

[0160] Example 2 Mesitylene, which has a boiling point of 165°C, was used as the organic solvent. The polarity term δp in the Hansen solubility parameters of mesitylene is 0.6. The positive electrode material was prepared using the method described above and dried in an argon atmosphere using the method described above. A battery was fabricated using this and a charge / discharge test was performed.

[0161] Example 3 Tetralin, which has a boiling point of 208°C, was used as the organic solvent. The polarity term δp in the Hansen solubility parameters of tetralin is 2.0. The positive electrode material was prepared using the method described above and dried in an argon atmosphere using the method described above. A battery was fabricated using this and a charge / discharge test was performed.

[0162] Comparative Example 1 The organic solvent used was 1,2,4-trichlorobenzene, which has a boiling point of 213°C. The polarity term δp in the Hansen solubility parameters of 1,2,4-trichlorobenzene is 4.2. The positive electrode material was prepared using the method described above and dried in an argon atmosphere using the same method. A secondary battery was fabricated using this and a charge / discharge test was performed.

[0163] [Table 1]

[0164] ≪Consideration≫ Table 1 shows the charge-discharge efficiency of the batteries of Examples 1 to 3 and Comparative Example 1, in which the positive electrodes were fabricated using organic solvents with different boiling points. The batteries of Examples 1 to 3, which used organic solvents with boiling points of 212°C or less, had dramatically improved charge-discharge efficiency compared to the battery of Comparative Example 1, which used an organic solvent with a boiling point above 212°C. This is thought to be because in Comparative Example 1, a large amount of solvent remained during drying, and this residual solvent deteriorated the oxyhalide solid electrolyte at high potentials. [Industrial Applicability]

[0165] The battery of the present disclosure can be used, for example, as an all-solid-state lithium-ion secondary battery. [Explanation of symbols]

[0166] 1000 Positive electrode materials 100 solid electrolyte 110 Cathode active material 111 Organic Solvents 2000 positive plates 201 Positive electrode 202 Current collector 3000 batteries 301 Positive electrode 302 Solid electrolyte layer 303 Negative electrode

Claims

1. a positive electrode active material; a solid electrolyte; an organic solvent; Including, the solid electrolyte comprises Li, M, O, and X; M is at least one selected from the group consisting of Ta and Nb, X is at least one selected from the group consisting of F, Cl, Br, and I; The organic solvent has a boiling point of 212°C or less. Positive electrode material.

2. The organic solvent has a boiling point of 208°C or less. The positive electrode material according to claim 1 .

3. In the solid electrolyte, X contains Cl. The positive electrode material according to claim 1 .

4. The solid electrolyte contains a crystalline phase in which at least one peak exists in a diffraction angle 2θ range of 11.05° or more and 13.86° or less in an X-ray diffraction pattern obtained by X-ray diffraction measurement using Cu-Kα radiation as a radiation source. The positive electrode material according to claim 1 .

5. In the solid electrolyte, the molar ratio O / X of O to X is 0.16 or more and 0.35 or less; The positive electrode material according to claim 1 .

6. In the solid electrolyte, the molar ratio Li / M of Li to M is 0.60 or more and 2.4 or less; The positive electrode material according to claim 1 .

7. The molar ratio Li / M is 0.96 or more and 1.20 or less. The positive electrode material according to claim 6 .

8. The organic solvent contains at least one selected from the group consisting of compounds having a halogen group and hydrocarbons. The positive electrode material according to claim 1 .

9. The compound having a halogen group has only a halogen group as a functional group. The positive electrode material according to claim 8 .

10. The organic solvent comprises an aromatic compound. The positive electrode material according to claim 1 .

11. the organic solvent includes at least one selected from the group consisting of tetralin, mesitylene, xylene, cumene, pseudocumene, ethylbenzene, chlorobenzene, 2,4-dichlorobenzene, o-chlorotoluene, 1,3-dichlorobenzene, p-chlorotoluene, 1,2-dichlorobenzene, 1,4-dichlorobutane, 2,4-dichlorotoluene, and 3,4-dichlorotoluene; The positive electrode material according to claim 1 .

12. The organic solvent includes at least one selected from the group consisting of tetralin, mesitylene, and xylene. The positive electrode material according to claim 11.

13. The organic solvent has a polarity parameter δp of 4.3 or less in Hansen solubility parameters. The positive electrode material according to claim 1 .

14. Removing the organic solvent from the cathode material according to any one of claims 1 to 13; A method for producing a positive electrode comprising the steps of:

15. Coating a positive electrode material according to any one of claims 1 to 13 onto a current collector; removing the organic solvent from the positive electrode material coated on the current collector; A method for manufacturing a positive electrode plate, comprising:

16. A method for manufacturing a battery including a positive electrode, a negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode, Obtaining the positive electrode by removing the organic solvent from the positive electrode material according to any one of claims 1 to 13; A method for manufacturing a battery, comprising:

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