Solid electrolyte

Abstract

To provide a solid electrolyte having suitably controlled grain boundary resistance.SOLUTION: A solid electrolyte of the present invention is represented by the following composition formula (1): (Li7-3xGax+a)(La3-y-z-wNdyYzMw)Zr2O12 (1). (In the formula (1), M is at least one kind selected from the group consisting of Ca, Sr, and Rb, where 0.10≤x<1.00, 0.01≤y≤0.20, 0.01≤z≤0.15, and 0.01≤w≤0.20 are satisfied. In the case of M being Ca or Sr (valence 2+), a is 0.05 / 3 for one kind, (0.05×2) / 3 for two kinds, and (0.05×3) / 3 for three kinds; or in the case of M being Rb (valence 1+), a is (0.05×2) / 3 for one kind).SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Lithium ion batteries (including primary and secondary batteries) are used as power sources for many electrical devices, including portable information devices. Among them, all-solid-state lithium ion batteries that use a solid electrolyte for lithium conduction between the positive and negative electrodes have been proposed as lithium ion batteries that combine high energy density with safety (see, for example, Patent Document 1).

[0003] Solid electrolytes are attracting attention as highly safe materials because they can conduct lithium ions without using an organic electrolyte solution and do not leak or volatilize due to heat generated by driving.

[0004] The solid electrolytes used in such all-solid-state lithium-ion batteries are oxide-based solid electrolytes that have high lithium-ion conductivity, excellent insulation properties, and high chemical stability. Among such oxides, lanthanum zirconate-based materials have particularly high lithium-ion conductivity and are expected to be used in batteries. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2009-215130 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, because such solid electrolytes have high lithium ion conductivity, the presence of trace amounts of moisture or carbon dioxide, even when working in a dry room, can easily lead to the formation of lithium carbonate, and the lithium ion conductivity at the interfaces and grain boundaries cannot be maintained and is easily reduced. [Means for solving the problem]

[0007] The present invention has been made to solve the above-mentioned problems, and can be realized as the following application examples.

[0008] The solid electrolyte according to an embodiment of the present invention is represented by the following composition formula (1). (Li 7-3x Ga x+a )(La 3-y-z-w Nd y Y z M w )Zr 2 O 12 (1) (In formula (1), M is at least one selected from the group consisting of Ca, Sr, and Rb, and satisfies 0.10≦x<1.00, 0.01≦y≦0.20, 0.01≦z≦0.15, and 0.01≦w≦0.20. When M is Ca or Sr with a valence of 2+, a is 0.05 / 3 for one type, (0.05×2) / 3 for two types, and (0.05×3) / 3 for three types. When M is Rb with a valence of 1+, a is (0.05×2) / 3 for one type.) [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a vertical cross-sectional view that illustrates a schematic diagram of a method for producing a solid electrolyte according to a first embodiment. [Diagram 2] FIG. 2 is a vertical cross-sectional view that illustrates a method for producing a solid electrolyte according to the second embodiment. [Diagram 3] FIG. 3 is a schematic perspective view showing the structure of a lithium ion battery as a battery of a preferred embodiment. [Figure 4] FIG. 4 is a flowchart showing a method for manufacturing the battery of the first embodiment. [Diagram 5]FIG. 5 is a vertical cross-sectional view that illustrates a manufacturing method for the battery of the first embodiment. [Figure 6] FIG. 6 is a vertical cross-sectional view that illustrates a manufacturing method for the battery of the first embodiment. [Figure 7] FIG. 7 is a flowchart showing a method for manufacturing a battery according to the second embodiment. [Figure 8] FIG. 8 is a vertical cross-sectional view that illustrates a manufacturing method for the battery of the second embodiment. [Figure 9] FIG. 9 is a vertical cross-sectional view that illustrates a manufacturing method for the battery of the second embodiment. [Figure 10] FIG. 10 is a flowchart showing a method for manufacturing a battery according to the third embodiment. [Figure 11] FIG. 11 is a vertical cross-sectional view that illustrates a manufacturing method for the battery of the third embodiment. [Figure 12] FIG. 12 is a vertical cross-sectional view that illustrates a manufacturing method for the battery of the third embodiment. [Figure 13] FIG. 13 is a vertical cross-sectional view that illustrates a manufacturing method for the battery of the third embodiment. [Figure 14] FIG. 14 is a flowchart showing a method for manufacturing the battery of the fourth embodiment. [Figure 15] FIG. 15 is a vertical cross-sectional view that illustrates a manufacturing method for the battery of the fourth embodiment. [Figure 16] FIG. 16 is a vertical sectional view that illustrates a manufacturing method for the battery of the fourth embodiment. [Figure 17] FIG. 17 is a vertical sectional view that illustrates a manufacturing method for the battery of the fourth embodiment. [Figure 18] FIG. 18 is a perspective view showing a configuration of a wearable device as an electronic device. [Figure 19] FIG. 19 is a table showing the compositions and crystal phases of the solid electrolytes of Examples 1 to 7 and Comparative Examples 1 to 4. [Figure 20] FIG. 20 is a table showing the evaluation results of Examples 1 to 7 and Comparative Examples 1 to 4. [Figure 21]FIG. 21 is a table showing the compositions and crystal phases of the solid electrolytes of Examples 8 to 14 and Comparative Examples 5 to 10. [Figure 22] FIG. 22 is a table showing the evaluation results of Examples 8 to 14 and Comparative Examples 5 to 10. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Preferred embodiments of the present invention will now be described in detail. [1] Solid electrolyte First, the solid electrolyte of the present invention will be described.

[0011] The solid electrolyte of the present invention is represented by the following composition formula (1). (Li 7-3x Ga x+a )(La 3-y-z-w Nd y Y z M w )Zr 2 O 12 (1) (In formula (1), M is at least one selected from the group consisting of Ca, Sr, and Rb, and satisfies 0.10≦x<1.00, 0.01≦y≦0.20, 0.01≦z≦0.15, and 0.01≦w≦0.20. When M is Ca or Sr with a valence of 2+, a is 0.05 / 3 for one type, (0.05×2) / 3 for two types, and (0.05×3) / 3 for three types. When M is Rb with a valence of 1+, a is (0.05×2) / 3 for one type.)

[0012] By satisfying these conditions, it is possible to provide a solid electrolyte with high lithium ion conductivity and with controlled grain boundary resistance by increasing the number of substitution species. More specifically, by substituting a portion of the lithium site with Ga, the arrangement of Li, which contributes greatly to conductivity, provides high lithium ion conductivity, while by substituting a portion of the lanthanum site with Nd, Y, and M, it is possible to provide a solid electrolyte that reduces grain boundary resistance and exhibits high total ion conductivity, including the grain boundaries. The substitution elements are those with an ionic radius of La 3+ Selection was made with a focus on larger or equivalent elements.

[0013] On the other hand, if the above conditions are not met, the above excellent effects cannot be obtained.

[0014] For example, in a solid electrolyte, Y mainly has the effect of increasing the oxidation resistance of the solid electrolyte. Therefore, if the solid electrolyte does not contain Y, it becomes difficult to prevent lithium in the electrolyte from being carbonated and becoming highly resistive.

[0015] Furthermore, if the solid electrolyte does not contain Nd, the grain growth mode is not promoted during sintering, and the generation of grain boundaries increases, making it impossible to sufficiently increase the total ionic conductivity, including the grain boundaries.

[0016] Furthermore, if the solid electrolyte does not contain M, there arises a problem that it is not possible to reduce the grain boundary resistance and increase the lithium ion conductivity.

[0017] Furthermore, if the solid electrolyte does not contain Ga, it becomes difficult to sufficiently increase the lithium ion conductivity itself.

[0018] Furthermore, even if the solid electrolyte is a lanthanum zirconate lithium-based material containing Nd, Y, M, and Ga, if the content of Nd in the solid electrolyte is too low, in other words, if the value of y is too small, the grain growth mode is not promoted during sintering, and the generation of grain boundaries increases, making it difficult to sufficiently increase the total ionic conductivity including the grain boundaries.

[0019] Furthermore, even if the solid electrolyte is a lithium lanthanum zirconate-based material containing Nd, Y, M, and Ga, if the content of Nd in the solid electrolyte is too high, in other words, if the value of y is too large, the crystal system cannot be maintained and it becomes difficult to stably increase the lithium ion conductivity.

[0020] Furthermore, even if the solid electrolyte is a lithium lanthanum zirconate-based material containing Nd, Y, M, and Ga, if the content of Y in the solid electrolyte is too low, in other words, if the value of z is too small, the amount of Y in the solid electrolyte, which mainly has the effect of increasing the oxidation resistance of the solid electrolyte, becomes insufficient, making it difficult to suppress carbonated lithium in the electrolyte and high resistance.

[0021] Furthermore, even if the solid electrolyte is a lithium lanthanum zirconate-based material containing Nd, Y, M, and Ga, if the content of Y in the solid electrolyte is too high, in other words, if the value of z is too large, the crystal system cannot be maintained, making it difficult to stably increase the lithium ion conductivity.

[0022] Furthermore, even if the solid electrolyte is a lanthanum lithium zirconate-based material containing Nd, Y, M, and Ga, if the content of M in the solid electrolyte is too low, in other words, if the value of w is too small, it becomes difficult to increase the lithium ion conductivity, including the grain boundaries.

[0023] Furthermore, even if the solid electrolyte is a lanthanum zirconate lithium-based material containing Nd, Y, M, and Ga, if the content of M in the solid electrolyte is too high, in other words, if the value of w is too large, the crystal system cannot be maintained, making it difficult to stably increase the lithium ion conductivity.

[0024] Furthermore, even if the solid electrolyte is a lithium lanthanum zirconate-based material containing Nd, Y, M, and Ga, if the Ga content in the solid electrolyte is too low, in other words, if the value of x is too small, it becomes difficult to sufficiently increase the lithium ion conductivity itself.

[0025] Furthermore, even if the solid electrolyte is a lanthanum zirconate lithium-based material containing Nd, Y, M, and Ga, if the Ga content in the solid electrolyte is too high, in other words, if the value of x is too large, the Li configuration that increases the lithium ion conductivity is no longer obtained, making it difficult to stably increase the lithium ion conductivity.

[0026] As described above, in the composition formula (1), x may satisfy the condition 0.10≦x<1.00, preferably 0.12≦x≦0.90, more preferably 0.15≦x≦0.70, and further preferably 0.20≦x≦0.50. This makes the above-mentioned effects more pronounced.

[0027] As described above, in the composition formula (1), y may satisfy the condition 0.01≦y≦0.20, preferably 0.02≦y≦0.18, more preferably 0.03≦y≦0.16, and further preferably 0.04≦y≦0.10. This makes the above-mentioned effects more pronounced.

[0028] As described above, in the composition formula (1), z may satisfy the condition 0.01≦z≦0.15, preferably 0.02≦z≦0.14, more preferably 0.03≦z≦0.13, and further preferably 0.04≦z≦0.10. This makes the above-mentioned effects more pronounced.

[0029] As described above, in the composition formula (1), w may satisfy the condition 0.01≦w≦0.20, preferably 0.02≦w≦0.19, more preferably 0.03≦w≦0.18, and further preferably 0.04≦w≦0.17. This makes the above-mentioned effects more pronounced.

[0030] In the solid electrolyte, Li is mainly contained in the basic skeleton of the garnet-type lithium ion conductor Li 7 La 3 Zr 2 O 12 In ZnO, they exist at the C site and interstitial sites and contribute to lithium ion conductivity.

[0031] In the solid electrolyte, La is mainly contained in the garnet-type lithium ion conductor Li 7 La 3 Zr 2 O 12 Configure La 3+ Occupies A site.

[0032] In the solid electrolyte, Zr is mainly contained in the basic skeleton of the garnet-type lithium ion conductor Li 7 La 3 Zr 2 O 12 Constituting Zr 4+ and occupies site B.

[0033] In the solid electrolyte, Ga mainly functions to expand the path through which lithium ions move and increase the lithium ion conductivity.

[0034] In solid electrolytes, Nd mainly functions to promote the grain growth mode during sintering and reduce the generation of grain boundaries, thereby reducing grain boundary resistance and improving the total lithium ion conductivity.

[0035] In the solid electrolyte, Y mainly has the effect of increasing the oxidation resistance of the solid electrolyte, and exerts the function of suppressing the carbonated state of lithium in the electrolyte, which leads to high resistance.

[0036] In the solid electrolyte, M is mainly Rb + , Ca 2+ , Sr 2+ Since the valence of Li is smaller than that of La, it exhibits the function of causing high ionic conductivity by changing the Li arrangement, including Ga, in the LLZO lattice.

[0037] Furthermore, by combining it with Y, Nd, and M in the solid electrolyte, the characteristics of each are generated in a balanced manner, the grain boundary resistance is not increased, and the lithium ion conductivity, including the grain boundaries, is improved.

[0038] M may be at least one selected from the group consisting of Ca, Sr and Rb, and may be one selected from the group consisting of Ca, Sr and Rb.

[0039] This allows Rb + , Ca 2+ , Sr 2+ Since the valence of Li is smaller than that of La, the change in the Li arrangement, including Ga, in the LLZO lattice causes high ionic conductivity, and by increasing the number of elements in addition to Nd and Y, the effect of reducing grain boundary resistance can be obtained.

[0040] Furthermore, M may be two or more elements selected from the group consisting of Ca, Sr, and Rb.

[0041] This allows Rb + , Ca 2+ , Sr 2+ Since the valence of Li is smaller than that of La, the change in the Li arrangement to include Ga in the LLZO lattice causes high ionic conductivity, and when more elements are added in addition to Nd and Y, the effect of reducing grain boundary resistance is obtained.

[0042] In addition to the elements constituting the composition formula (1), the solid electrolyte of the present invention may contain trace amounts of other elements, i.e., elements other than Li, Ga, La, Nd, Y, Ca, Sr, Rb, Zr, and O. The other elements may be one type or two or more types.

[0043] The content of the other elements contained in the solid electrolyte of the present invention is preferably 100 ppm or less, and more preferably 50 ppm or less.

[0044] When two or more elements are contained as the other elements, the sum of the contents of these elements is adopted as the content of the other elements.

[0045] The crystal phase of the solid electrolyte of the present invention is usually a cubic garnet-type crystal. The solid electrolyte of the present invention may be used alone or in combination with other components, for example. More specifically, the solid electrolyte of the present invention may be used alone to form a solid electrolyte layer in a battery, or may be used in a mixed state with another solid electrolyte to form a solid electrolyte layer. In addition, for example, the solid electrolyte of the present invention may be used in a mixed state with a positive electrode active material to form a positive electrode layer, or may be used in a mixed state with a negative electrode active material to form a negative electrode layer.

[0046] [2] Manufacturing method of solid electrolyte Next, a method for producing the solid electrolyte of the present invention, that is, the solid electrolyte represented by the above composition formula (1), will be described. In the following description, the solid electrolyte represented by the above composition formula (1) is also referred to as a first electrolyte.

[0047] [2-1] First embodiment The method for producing the solid electrolyte according to the first embodiment will be described below. FIG. 1 is a vertical cross-sectional view that illustrates a schematic diagram of a method for producing a solid electrolyte according to a first embodiment.

[0048] 1, the method for producing a solid electrolyte according to the present embodiment includes the following steps: a first mixing step (1A) of mixing a plurality of raw materials containing metal elements constituting the lithium composite metal oxide represented by the above composition formula (1) to obtain a first mixture P1, a first heating step (1B) of subjecting the first mixture P1 to a first heat treatment to obtain a pre-sintered body P2, and a second heating step (1C) of subjecting the pre-sintered body P2 to a second heat treatment to form a crystalline solid electrolyte P3' represented by the above composition formula (1), i.e., the first electrolyte P3'.

[0049] This makes it possible to provide a method for producing a solid electrolyte that can suitably produce a solid electrolyte P100 that can suitably maintain a high total ion conductivity even in the atmosphere. More specifically, by substituting a part of the lanthanum sites of a lanthanum zirconate lithium-based material with Nd, Y, and M and substituting a part of the lithium sites with Ga, it is possible to provide a method for producing a solid electrolyte that can suitably produce a solid electrolyte P100 that has high acid resistance, can suppress the generation of lithium carbonate caused by carbon dioxide, and exhibits high total ion conductivity even in the atmosphere.

[0050] In the illustrated configuration, the entire solid electrolyte P100 finally obtained is the first electrolyte portion P3 composed essentially of only the first electrolyte P3', but the solid electrolyte P100 may have a portion composed of a component other than the first electrolyte P3'.

[0051] [2-1-1] First mixing step In the first mixing step, a plurality of raw materials containing the metal elements contained in the above composition formula (1) are mixed to obtain a first mixture P1.

[0052] In this step, the first mixture P1 obtained by mixing a plurality of raw materials needs to contain two or more metal elements among the metal elements contained in the above composition formula (1) as a whole.

[0053] At least one of the multiple raw materials used in this step may be an oxoacid compound containing an oxoanion as well as a metal ion.

[0054] This allows the first electrolyte P3' and solid electrolyte P100 having desired properties to be stably formed by a heat treatment at a relatively low temperature for a relatively short time. More specifically, by using an oxo acid compound in this step, a pre-sintered body P2 containing an oxide different from the first electrolyte P3' and an oxo acid compound can be obtained in a later step. As a result, the melting point of the oxide is lowered, and crystal growth is promoted by the sintering treatment, which is a heat treatment at a relatively low temperature for a relatively short time, and an adhesive interface with the adherend can be formed.

[0055] The oxoanions constituting the oxoacid compound do not contain metal elements, and examples thereof include halogen oxoacids, borate ions, carbonate ions, orthocarbonate ions, carboxylate ions, silicate ions, nitrite ions, nitrate ions, phosphite ions, phosphate ions, arsenate ions, sulfite ions, sulfate ions, sulfonate ions, and sulfinate ions. Examples of halogen oxoacids include hypochlorite ions, chlorite ions, chlorate ions, perchlorate ions, hypobromite ions, bromite ions, bromate ions, perbromate ions, hypoiodite ions, iodite ions, iodate ions, and periodate ions. Among these, the oxoacid compound preferably contains at least one of nitrate ions and sulfate ions as the oxoanion, and more preferably contains nitrate ions.

[0056] This makes it possible to more suitably lower the melting point of the metal oxide contained in the calcined body P2 obtained in the first heating step described later in detail, and more effectively promote the crystal growth of the lithium-containing composite oxide. As a result, even if the second heating step described later is performed at a lower temperature for a shorter period of time, it is possible to suitably obtain the first electrolyte P3' and solid electrolyte P100 having particularly excellent ion conductivity. In the following description, the metal oxide contained in the calcined body P2 obtained in the first heating step is also referred to as the "precursor oxide."

[0057] The raw material containing a metal element may be, for example, an elemental metal or an alloy, a compound containing only one type of metal element in its molecule, or a compound containing multiple types of metal elements in its molecule.

[0058] Examples of the lithium compound, which is a raw material containing Li, include lithium metal salts, lithium alkoxides, and lithium hydroxide, and one or more of these can be used in combination. Examples of the lithium metal salts include lithium chloride, lithium nitrate, lithium sulfate, lithium acetate, lithium carbonate, and (2,4-pentanedionato)lithium. Examples of the lithium alkoxides include lithium methoxide, lithium ethoxide, lithium propoxide, lithium isopropoxide, lithium butoxide, lithium isobutoxide, lithium sec-butoxide, lithium tert-butoxide, and dipivaloylmethanatolithium. Among these, the lithium compound is preferably one or more selected from the group consisting of lithium nitrate, lithium sulfate, and (2,4-pentanedionato)lithium. Hydrates may be used as the raw material containing Li.

[0059] Examples of the lanthanum compound, which is a raw material containing La, include lanthanum metal salt, lanthanum alkoxide, lanthanum hydroxide, etc., and one or more of these can be used in combination. Examples of the lanthanum metal salt include lanthanum chloride, lanthanum nitrate, lanthanum sulfate, lanthanum acetate, lanthanum tris(2,4-pentanedionato), etc. Examples of the lanthanum alkoxide include lanthanum trimethoxide, lanthanum triethoxide, lanthanum tripropoxide, lanthanum triisopropoxide, lanthanum tributoxide, lanthanum triisobutoxide, lanthanum trisec-butoxide, lanthanum tritertiarybutoxide, lanthanum dipivaloylmethanatolanthanum, etc. Among them, the lanthanum compound is preferably at least one selected from the group consisting of lanthanum nitrate, lanthanum tris(2,4-pentanedionato), and lanthanum hydroxide. A hydrate may be used as the raw material containing La.

[0060] Examples of the zirconium compound, which is a raw material containing Zr, include zirconium metal salts and zirconium alkoxides, and one or more of these can be used in combination. Examples of the zirconium metal salts include zirconium chloride, zirconium oxychloride, zirconium oxynitrate, zirconium oxysulfate, zirconium oxyacetate, and zirconium acetate. Examples of the zirconium alkoxides include zirconium tetramethoxide, zirconium tetraethoxide, zirconium tetrapropoxide, zirconium tetraisopropoxide, zirconium tetranormal butoxide, zirconium tetraisobutoxide, zirconium tetrasecondary butoxide, zirconium tetratertiary butoxide, and dipivaloylmethanatozirconium. Among these, zirconium compounds are preferably zirconium tetranormal butoxide. Hydrates may be used as raw materials containing Zr.

[0061] Examples of the gallium compound, which is a raw material containing Ga, include gallium metal salt, gallium alkoxide, gallium hydroxide, etc., and one or more of these can be used in combination. Examples of the gallium metal salt include gallium chloride, gallium nitrate, gallium sulfate, gallium acetate, etc. Examples of the gallium alkoxide include gallium trimethoxide, gallium triethoxide, gallium tripropoxide, gallium triisopropoxide, gallium tributoxide, gallium triisobutoxide, gallium trisec-butoxide, gallium tritertiary butoxide, and dipivaloylmethanatogallium, etc. Among them, gallium nitrate is preferable as the gallium compound. As the raw material containing Ga, a hydrate may be used.

[0062] Examples of the neodymium compound, which is a raw material containing Nd, include neodymium metal salts, neodymium alkoxides, neodymium hydroxide, etc., and one or more of these can be used in combination. Examples of the neodymium metal salts include neodymium chloride, neodymium nitrate, neodymium sulfate, neodymium acetate, etc. Examples of the neodymium alkoxides include neodymium trimethoxide, neodymium triethoxide, neodymium tripropoxide, neodymium triisopropoxide, neodymium tributoxide, neodymium triisobutoxide, neodymium trisec-butoxide, neodymium tritertiary butoxide, and dipivaloylmethanatoneodimide, etc. Among them, neodymium nitrate is preferable as the neodymium compound. Hydrates may be used as the raw material containing Nd.

[0063] Examples of the yttrium compound, which is a raw material containing Y, include yttrium metal salt, yttrium alkoxide, yttrium hydroxide, etc., and one or more of these can be used in combination. Examples of the yttrium metal salt include yttrium chloride, yttrium nitrate, yttrium sulfate, yttrium acetate, yttrium tris(2,4-pentanedionato), etc. Examples of the yttrium alkoxide include yttrium trimethoxide, yttrium triethoxide, yttrium tripropoxide, yttrium triisopropoxide, yttrium tributoxide, yttrium triisobutoxide, yttrium trisec-butoxide, yttrium tritertiary butoxide, and yttrium dipivaloylmethanato. Among them, the yttrium compound is preferably at least one selected from the group consisting of yttrium nitrate, yttrium tris(2,4-pentanedionato), and yttrium hydroxide. As the raw material containing Y, a hydrate may be used.

[0064] Examples of calcium compounds that are raw materials containing Ca include calcium metal salts, calcium alkoxides, calcium hydroxide, etc., and one or more of these can be used in combination. Examples of calcium metal salts include calcium chloride, calcium fluoride, calcium nitrate, calcium acetate, etc. Examples of calcium alkoxides include calcium dimethoxide, calcium diethoxide, calcium diisopropoxide, calcium di-normal propoxide, calcium diisobutoxide, calcium di-normal butoxide, calcium di-secondary butoxide, etc. Among them, the calcium compound is preferably at least one selected from the group consisting of calcium nitrate and calcium di-normal butoxide. Hydrates may be used as raw materials containing Ca.

[0065] Examples of the strontium compound, which is a raw material containing Sr, include strontium metal salt, strontium alkoxide, strontium hydroxide, etc., and one or more of these can be used in combination. Examples of the strontium metal salt include strontium chloride, strontium nitrate, strontium sulfate, strontium acetate, etc. Examples of the strontium alkoxide include strontium isopropoxide, etc. Among them, the strontium compound is preferably at least one selected from the group consisting of strontium nitrate and strontium isopropoxide. Hydrates may be used as raw materials containing Sr.

[0066] Examples of the rubidium compound, which is a raw material containing Rb, include rubidium metal salt, rubidium alkoxide, rubidium hydroxide, etc., and one or more of these can be used in combination. Examples of the rubidium metal salt include rubidium chloride, rubidium fluoride, rubidium nitrate, rubidium acetate, etc. Examples of the rubidium alkoxide include rubidium isopropoxide, etc. Among them, rubidium nitrate and rubidium isopropoxide are preferred as the rubidium compound. Hydrates may be used as the raw material containing Rb.

[0067] A solvent may be used to prepare the first mixture P1. This makes it possible to more suitably mix a plurality of raw materials containing the metal elements contained in the above composition formula (1).

[0068] The solvent is not particularly limited, and for example, various organic solvents can be used, but more specifically, for example, alcohols, glycols, ketones, esters, ethers, organic acids, aromatics, amides, etc. can be mentioned, and a mixed solvent of one or more selected from these can be used. Examples of alcohols include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, allyl alcohol, 2-n-butoxyethanol, etc. Examples of glycols include ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, pentanediol, hexanediol, heptanediol, dipropylene glycol, etc. Examples of ketones include dimethyl ketone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, etc. Examples of esters include methyl formate, ethyl formate, methyl acetate, methyl acetoacetate, etc. Examples of ethers include 2-methoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and dipropylene glycol monomethyl ether. Examples of organic acids include formic acid, acetic acid, 2-ethylbutyric acid, and propionic acid. Examples of aromatics include toluene, o-xylene, and p-xylene. Examples of amides include formamide, N,N-dimethylformamide, N,N-diethylformamide, dimethylacetamide, and N-methylpyrrolidone. Among these, the solvent is preferably at least one of 2-n-butoxyethanol and propionic acid.

[0069] When a solvent is used in preparing the first mixture P1, the solvent may be at least partially removed prior to the first heating step described in detail below.

[0070] The removal of the solvent prior to the first heating step can be carried out, for example, by heating the first mixture P1, placing it in a reduced pressure environment, or placing it under room temperature and normal pressure. By removing at least a portion of the solvent, the first mixture P1 can be suitably gelled. In this specification, room temperature and normal pressure refers to 25° C. and 1 atm.

[0071] Hereinafter, when the solvent is removed by a heat treatment, the heat treatment is also referred to as a pre-heat treatment. The conditions of the preheating treatment depend on the boiling point and vapor pressure of the solvent, but the heating temperature of the preheating treatment is preferably 50°C or higher and 250°C or lower, more preferably 60°C or higher and 230°C or lower, and even more preferably 80°C or higher and 200°C or lower. The heating temperature may be changed during the preheating treatment. For example, the preheating treatment may have a first stage in which the heat treatment is performed while maintaining the temperature at a relatively low temperature, and a second stage in which the temperature is raised after the first stage and the heat treatment is performed at a relatively high temperature. In such a case, it is preferable that the maximum temperature during the preheating treatment is within the above-mentioned range.

[0072] The heating time in the preliminary heating treatment is preferably from 10 minutes to 180 minutes, more preferably from 20 minutes to 120 minutes, and even more preferably from 30 minutes to 60 minutes.

[0073] The preheating treatment may be performed in any atmosphere, including an oxidizing atmosphere such as air or an oxygen gas atmosphere, or a non-oxidizing atmosphere such as an inert gas atmosphere such as nitrogen gas, helium gas, argon gas, etc. The preheating treatment may be performed under reduced pressure or vacuum, or under pressure.

[0074] During the preheating treatment, the atmosphere may be maintained at substantially the same conditions or may be changed to different conditions. For example, the preheating treatment may have a first stage in which heat treatment is performed in a normal pressure environment and a second stage in which heat treatment is performed in a reduced pressure environment after the first stage.

[0075] [2-1-2] First heating step In the first heating step, the first mixture P1 obtained in the first mixing step, for example, the gelled first mixture P1, is subjected to a first heat treatment to form a calcined body P2.

[0076] In particular, when an oxoacid compound is used as part of the raw materials, a pre-fired body P2 is obtained that contains a precursor oxide, which is an oxide different from the first electrolyte P3', and the oxoacid compound.

[0077] The heating temperature in the first heating step is not particularly limited, but is preferably 500°C or higher and 650°C or lower, more preferably 510°C or higher and 650°C or lower, and even more preferably 520°C or higher and 600°C or lower.

[0078] This makes it possible to more effectively prevent the metal elements constituting the first electrolyte P3' from unintentionally evaporating, in particular Li, which is easily volatilized among metal materials, and thus makes it possible to more strictly control the composition of the first electrolyte P3' and more efficiently produce the first electrolyte P3' and the solid electrolyte P100.

[0079] The heating temperature may be changed during the first heating step. For example, the first heating step may have a first stage in which the heat treatment is performed while maintaining the temperature at a relatively low temperature, and a second stage in which the temperature is raised after the first stage and the heat treatment is performed at a relatively high temperature. In such a case, it is preferable that the maximum temperature in the first heating step is within the above-mentioned range.

[0080] Furthermore, the heating time in the first heating step, particularly the heating time at a heating temperature of 500°C or more and 650°C or less, is preferably 5 minutes or more and 180 minutes or less, more preferably 10 minutes or more and 120 minutes or less, and even more preferably 15 minutes or more and 90 minutes or less.

[0081] The first heating step may be performed in any atmosphere, including an oxidizing atmosphere such as air or an oxygen gas atmosphere, or a non-oxidizing atmosphere such as an inert gas atmosphere such as nitrogen gas, helium gas, or argon gas. The first heating step may be performed under reduced pressure, vacuum, or pressure. In particular, the first heating step is preferably performed in an oxidizing atmosphere.

[0082] In addition, during the first heating step, the atmosphere may be maintained at substantially the same conditions or may be changed to different conditions. For example, the first heating step may have a first stage in which heat treatment is performed in an inert gas atmosphere, and a second stage in which heat treatment is performed in an oxidizing atmosphere after the first stage.

[0083] The calcined body P2 obtained as described above usually contains a precursor oxide having a different crystal phase from that of the first electrolyte P3', i.e., the solid electrolyte represented by the composition formula (1) at room temperature and normal pressure. In this specification, the term "different" in relation to the crystal phase is a broad concept that includes not only crystal phases of different types but also crystal phases of the same type but with at least one lattice constant different.

[0084] Examples of the crystal phase of the precursor oxide include cubic crystals such as pyrochlore type crystals, perovskite structure, rock salt type structure, diamond structure, fluorite type structure, and spinel type structure, orthorhombic crystals such as ramsdellite type, and trigonal crystals such as corundum type, with pyrochlore type crystals being preferred.

[0085] This makes it possible to suitably obtain a solid electrolyte having particularly excellent ion conductivity even when the conditions in the second heating step described below are lower temperature and shorter time.

[0086] The crystal grain size of the precursor oxide is not particularly limited, but is preferably 10 nm or more and 200 nm or less, more preferably 15 nm or more and 180 nm or less, and even more preferably 20 nm or more and 160 nm or less.

[0087] This allows the melting temperature of the precursor oxide and the firing temperature in the second heating step to be further reduced by the so-called Gibbs-Thomson effect, which is a melting point drop phenomenon associated with an increase in surface energy. This is also advantageous in improving the bonding between the solid electrolyte P100 produced by the method of this embodiment and different materials and reducing the defect density.

[0088] The precursor oxide preferably consists essentially of a single crystalline phase. As a result, when the solid electrolyte P100 is produced using the method of the present embodiment, i.e., when the high-temperature crystal phase is generated, the crystal phase transition that occurs is substantially limited to one time, so that segregation of elements accompanying the crystal phase transition and generation of impurity crystals due to thermal decomposition are suppressed, and various properties of the produced solid electrolyte P100 are further improved.

[0089] In addition, when the pre-sintered body P2 obtained in the first heating step is measured by TG-DTA at a heating rate of 10°C / min, if only one exothermic peak is observed in the range of 300°C or more and 1000°C or less, it can be determined that the pre-sintered body P2 is "substantially composed of a single crystalline phase."

[0090] The composition of the precursor oxide is not particularly limited, but the precursor oxide is preferably a double oxide, and more preferably a double oxide containing La and Y.

[0091] This makes it possible to obtain a solid electrolyte P100 having particularly excellent ion conductivity even when the heat treatment in the second heating step described below is performed at a lower temperature for a shorter time. Also, for example, in an all-solid-state secondary battery, the adhesion of the first electrolyte P3' to the positive electrode active material and the negative electrode active material can be improved, and the mixture can be formed to have a better adhesive interface, thereby improving the characteristics and reliability of the all-solid-state secondary battery.

[0092] The calcined body P2 obtained as described above is usually one in which most of the solvent used in the production process has been removed, but some of the solvent may remain. However, the content of the solvent in the calcined body P2 is preferably 1.0 mass % or less, and more preferably 0.1 mass % or less.

[0093] [2-1-3] Second heating step In the second heating step, the pre-sintered body P2 obtained in the first heating step is subjected to a second heat treatment to form a crystalline solid electrolyte (first electrolyte) P3' represented by the above composition formula (1).

[0094] In particular, if the calcined body P2 obtained in the first heating step contains an oxo acid compound, the melting point of the precursor oxide can be suitably lowered, the crystal growth of the lithium-containing composite oxide can be promoted, and the first electrolyte P3' having the desired properties can be stably formed by heat treatment at a relatively low temperature for a relatively short time. Also, the adhesion between the solid electrolyte P100 formed and the adherend can be improved.

[0095] The second heating step may be carried out after mixing other components with the above-mentioned calcined body P2.

[0096] For example, the mixture of the pre-calcined body P2 and the oxo acid compound may be subjected to the second heating step. Even in such a case, the same effect as described above can be obtained.

[0097] Specific examples of oxo acid compounds that can be mixed with the calcined body P2 include the oxo acid compounds contained in the metal compounds exemplified as raw materials for the first mixture P1 described above.

[0098] In the second heating step, the above-mentioned pre-sintered body P2 may be subjected to the heating step in a state where it is mixed with an active material such as a positive electrode active material or a negative electrode active material. The positive electrode active material and the negative electrode active material will be described in detail later.

[0099] The composition subjected to the second heating step contains, as a whole, a plurality of metal elements as constituent elements of the first electrolyte P3′, and the ratio of the contents of these elements usually corresponds to the composition of the target solid electrolyte, i.e., the content ratio of each metal element in the above composition formula (1).

[0100] When the composition to be subjected to this step contains an oxo acid compound, the content of the oxo acid compound in the composition is not particularly limited, but is preferably from 0.1% by mass to 20% by mass, more preferably from 1.5% by mass to 15% by mass, and even more preferably from 2.0% by mass to 10% by mass.

[0101] This makes it possible to more reliably prevent the oxo acid compound from unintentionally remaining in the solid electrolyte P100, while suitably carrying out the heat treatment in the second heating step at a lower temperature in a shorter time, thereby making it possible to provide the resulting solid electrolyte P100 with particularly excellent ionic conductivity.

[0102] The content of the precursor oxide in the composition to be subjected to this step is not particularly limited, but is preferably from 35% by mass to 90% by mass, and more preferably from 45% by mass to 85% by mass.

[0103] When the content of precursor oxide in the composition subjected to this process is XP [mass%] and the content of oxo acid compound in the composition subjected to this process is XO [mass%], it is preferable that the relationship 0.013≦XO / XP≦0.58 is satisfied, it is more preferable that the relationship 0.023≦XO / XP≦0.34 is satisfied, and it is even more preferable that the relationship 0.03≦XO / XP≦0.19 is satisfied.

[0104] This makes it possible to more reliably prevent the oxo acid compound from unintentionally remaining in the solid electrolyte P100, while suitably carrying out the heat treatment in the second heating step at a lower temperature in a shorter time, thereby providing the resulting solid electrolyte with particularly excellent ionic conductivity.

[0105] The heating temperature in the second heating step is not particularly limited, but is usually higher than the heating temperature in the first heating step, and is preferably 800°C or higher and 1000°C or lower, more preferably 800°C or higher and 950°C or lower, and even more preferably 800°C or higher and 900°C or lower.

[0106] This allows the solid electrolyte P100 having desired properties to be stably formed by a relatively low temperature and a relatively short heat treatment. In addition, since the solid electrolyte P100 can be produced by a relatively low temperature and a relatively short heat treatment, the productivity of the solid electrolyte P100 and all-solid-state batteries including the solid electrolyte can be improved, and this is also preferable from the viewpoint of energy saving.

[0107] The heating temperature may be changed during the second heating step. For example, the second heating step may have a first stage in which the heat treatment is performed while maintaining the temperature at a relatively low temperature, and a second stage in which the temperature is raised after the first stage and the heat treatment is performed at a relatively high temperature. In such a case, it is preferable that the maximum temperature in the second heating step is within the above-mentioned range.

[0108] The heating time in the second heating step, particularly the heating time at a heating temperature of 800°C or more and 1000°C or less, is not particularly limited, but is preferably 5 minutes or more and 600 minutes or less, more preferably 10 minutes or more and 540 minutes or less, and even more preferably 15 minutes or more and 500 minutes or less.

[0109] This allows the solid electrolyte P100 having desired properties to be stably formed by a relatively low temperature and a relatively short heat treatment. In addition, since the solid electrolyte P100 can be produced by a relatively low temperature and a relatively short heat treatment, the productivity of the solid electrolyte P100 and all-solid-state batteries including the solid electrolyte can be improved, and this is also preferable from the viewpoint of energy saving.

[0110] The second heating step may be performed in any atmosphere, including an oxidizing atmosphere such as air or an oxygen gas atmosphere, or a non-oxidizing atmosphere such as an inert gas atmosphere such as nitrogen gas, helium gas, or argon gas. The heating step may be performed under reduced pressure, vacuum, or pressure. In particular, the second heating step is preferably performed in an oxidizing atmosphere.

[0111] During the second heating step, the atmosphere may be maintained under substantially the same conditions, or may be changed to different conditions.

[0112] Even when an oxo acid compound is used as a raw material, the solid electrolyte P100 obtained as described above is usually substantially free of the oxo acid compound. More specifically, the content of the oxo acid compound in the obtained solid electrolyte is usually 100 ppm or less, preferably 50 ppm or less, and more preferably 10 ppm or less.

[0113] This makes it possible to suppress the content of undesirable impurities in the solid electrolyte P100, thereby improving the characteristics and reliability of the solid electrolyte.

[0114] [2-2] Second embodiment Next, a method for producing a solid electrolyte according to a second embodiment will be described. FIG. 2 is a vertical cross-sectional view that illustrates a method for producing a solid electrolyte according to the second embodiment.

[0115] Hereinafter, a method for producing a solid electrolyte according to the second embodiment will be described with reference to FIG. 2. The differences from the above-described embodiment will be mainly described, and a description of the same points will be omitted.

[0116] 2, the method for producing the solid electrolyte of this embodiment includes the following steps: a first mixing step (2A) of mixing a plurality of raw materials containing metal elements constituting the lithium composite metal oxide represented by the above composition formula (1) to obtain a first mixture P1, a heating step (2B) of subjecting the first mixture P1 to a heat treatment to obtain a first electrolyte part P3 composed of a material containing a first electrolyte P3', and a second electrolyte part forming step (2C) of melting a second electrolyte P4', particularly a second electrolyte P4' containing Li, B, and O, in a state in which the second electrolyte P4' is brought into contact with the first electrolyte part P3 to form a second electrolyte part P4 in contact with the first electrolyte part P3.

[0117] This makes it possible to provide a method for producing a solid electrolyte that can produce a solid electrolyte P100 that can favorably maintain a high total ion conductivity even in the atmosphere. More specifically, by substituting a part of the lanthanum site of a lanthanum zirconate lithium-based material with Nd, Y, and M and substituting a part of the lithium site with Ga, it is possible to provide a method for producing a solid electrolyte that can favorably produce a solid electrolyte P100 that has high acid resistance, can suppress the generation of lithium carbonate caused by carbon dioxide, and exhibits high total ion conductivity even in the atmosphere. In addition, it is possible to obtain an effect of increasing the density at low temperatures.

[0118] The first mixing step (2A) in this embodiment is similar to the first mixing step (1A) in the above-described embodiment, and therefore a description thereof will be omitted.

[0119] [2-2-1] Heating process The heating step can be carried out, for example, by the same method and under the same conditions as described in [2-1-3] above. It is preferable to carry out a first heating treatment by the same method and under the same conditions as described in [2-1-2] above, followed by a second heating treatment by the same method and under the same conditions as described in [2-1-3] above. This provides the same effects as those described in the first embodiment.

[0120] [2-2-2] Second electrolyte part formation process In the second electrolyte part forming step, with the second electrolyte P4' being in contact with the first electrolyte part P3 formed in the heating step, the second electrolyte P4' is melted to form a second electrolyte part P4 in contact with the first electrolyte part P3.

[0121] The second electrolyte P4' is, for example, LiBH 4 (melting point 268 °C), LiF (melting point 848 °C), LiCl (melting point 605 °C), LiBr (melting point 552 °C), LiI (melting point 469 °C), Li 3 BO 3 (melting point 817 °C), Li 2+x C 1-x B x O 3 (0.01 < x < 0.50) (melting point 680 °C to 750 °C), etc., oxides, halides, hydrides, borides, amorphous and partially crystalline glasses of these partial substituents, etc. can be used. Also, a solid solution in which some atoms of the above compounds are substituted with other transition metals, typical metals, alkali metals, alkaline earths, lanthanoids, chalcogenites, halogens, etc. may be used.

[0122] Among them, the second electrolyte P4' preferably has a composition containing Li, B, and O, more preferably has a composition containing Li, B, C, and O, and even more preferably is represented by the following composition formula (2). Li 2+x C 1-x B x O 3 ···(2) (In formula (2), 0.01 < x < 0.50 is satisfied.)

[0123] Thereby, it becomes easier to form the amorphous second electrolyte part P4, and the lithium ion conductivity of the solid electrolyte can be further improved.

[0124] In formula (2), it is only necessary to satisfy the condition of 0.01 < x < 0.50, but preferably satisfies the condition of 0.02 ≤ x ≤ 0.45, and more preferably satisfies the condition of 0.05 ≤ x ≤ 0.40. This makes the above-mentioned effects more pronounced.

[0125] The heating temperature in this step depends on the composition of the second electrolyte P4', but is preferably from 800°C to 1000°C, more preferably from 800°C to 950°C, and even more preferably from 800°C to 900°C.

[0126] Furthermore, the heating time in this step, particularly the heating time at a heating temperature of 800°C or more and 1000°C or less, is not particularly limited, but is preferably 5 minutes or more and 600 minutes or less, more preferably 10 minutes or more and 540 minutes or less, and even more preferably 15 minutes or more and 500 minutes or less.

[0127] [3] Complex Next, the composite according to the present invention will be described.

[0128] The composite according to the present invention comprises an active material and the solid electrolyte according to the present invention that covers a part of the surface of the active material.

[0129] This makes it possible to provide a composite that can favorably maintain a high total ion conductivity even in the atmosphere. In addition, it is possible to provide a composite that has a sufficiently low grain boundary resistance between the active material and the solid electrolyte. Such a composite can be favorably applied to a positive electrode composite or a negative electrode composite of a battery as described below. As a result, the characteristics and reliability of the battery as a whole can be improved.

[0130] In the composite, the solid electrolyte is present, for example, so as to fill spaces between particles of the active material or to be in contact with, particularly in close contact with, the surfaces of particles of the active material.

[0131] The active material constituting the composite according to the present invention includes a positive electrode active material and a negative electrode active material.

[0132] As the positive electrode active material, for example, an oxide containing Li and O, more specifically, a lithium composite oxide containing at least Li and at least one element selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, and Cu, can be used. As such a composite oxide, for example, LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , Li 2 Mn 2 O 3 , NMC(Li p (Ni x Mn 1-x-y Co y )O 2 ), LiCr 0.5 Mn 0.5 O 2 , LiFePO 4 , Li 2 FeP 2 O 7 , LiMnPO 4 , LiFeBO 3 , Li 3 V 2 (PO 4 ) 3 , Li 2 CuO 2 , Li 2 FeSiO 4 , Li 2 MnSiO 4 Examples of the positive electrode active material include LiFeF 3 Fluorides such as LiBH 4 Or Li 4 BN 3 H 10 boron complex compounds such as boron fluoride complexes, iodine complex compounds such as polyvinylpyridine-iodine complexes, and nonmetallic compounds such as sulfur can also be used.

[0133] The negative electrode active material is, for example, Nb 2 O 5 , V 2 O 5 , TiO 2 , In 2 O 3 , ZnO, SnO 2, NiO, ITO, AZO, GZO, ATO, FTO, Li 4 Ti 5 O 12 , Li 2 Ti 3 O 7 In addition, metals and alloys such as Li, Al, Si, Si-Mn, Si-Co, Si-Ni, Sn, Zn, Sb, Bi, In, and Au, carbon materials, LiC 24 , LiC 6 and the like, in which lithium ions are inserted between the layers of a carbon material.

[0134] The active material may have a coating layer formed on its surface for the purpose of reducing the interface resistance with the solid electrolyte and improving the electronic conductivity. For example, LiCoO 2 The surface of the positive electrode active material particles is coated with LiNbO 3 , Al 2 O 3 , ZrO 2 , Ta 2 O 5 The interface resistance of lithium ion conduction can be further reduced by forming a thin film such as a coating layer, etc. The thickness of the coating layer is not particularly limited, but is preferably 3 nm or more and 1 μm or less.

[0135] The average particle size of the active material is not particularly limited, but is preferably from 0.1 μm to 150 μm, and more preferably from 0.3 μm to 60 μm.

[0136] This makes it easier to achieve both an actual capacity density close to the theoretical capacity of the active material and a high charge / discharge rate.

[0137] In this specification, the average particle size refers to the average particle size based on volume, and can be determined, for example, by adding a sample to methanol, dispersing the sample for 3 minutes using an ultrasonic disperser, and measuring the dispersion using a Coulter Counter method particle size distribution measuring device (TA-II model, manufactured by COULTER ELECTRONICS INC.) with an aperture of 50 μm.

[0138] The particle size distribution of the active material is not particularly limited, and for example, in a particle size distribution having one peak, the half width of the peak may be 0.1 μm or more and 19 μm or less. In addition, the particle size distribution of the active material may have two or more peaks.

[0139] The active material may be of any shape, for example, spherical, columnar, plate-like, scaly, hollow, amorphous, etc., and may be a mixture of two or more of these.

[0140] When the content of active material in the composite is XA [mass%] and the content of solid electrolyte in the composite is XS [mass%], it is preferable to satisfy the relationship 0.1≦XS / XA≦8.3, it is more preferable to satisfy the relationship 0.3≦XS / XA≦4.1, and it is even more preferable to satisfy the relationship 0.6≦XS / XA≦2.1.

[0141] Furthermore, the composite may contain, in addition to the active material and solid electrolyte, for example, a conductive assistant, a binder, and the like.

[0142] However, the content of components other than the active material and solid electrolyte in the composite is preferably 10 mass % or less, more preferably 7 mass % or less, and even more preferably 5 mass % or less.

[0143] As the conductive assistant, any conductive material may be used as long as it is a conductor whose electrochemical interaction at the electrode reaction potential is negligible. More specifically, for example, carbon materials such as acetylene black, ketjen black, and carbon nanotubes, precious metals such as palladium and platinum, and SnO 2 , ZnO, RuO 2 or ReO 3 , Ir 2 O 3 For example, a conductive oxide such as the above can be used.

[0144] The composite according to the present invention can be suitably produced, for example, by applying the method for producing a solid electrolyte described in the above item [2].

[0145] [4]Battery Next, the battery according to the present invention will be described.

[0146] The battery according to the present invention includes a composite containing the solid electrolyte of the present invention and an active material as described above, an electrode provided on one surface of the composite, and a current collector provided on the other surface of the composite.

[0147] This makes it possible to provide a battery including a solid electrolyte that can favorably maintain a high total ion conductivity even in the atmosphere.

[0148] FIG. 3 is a schematic perspective view showing the structure of a lithium ion battery as a battery of a preferred embodiment.

[0149] 3, the lithium ion battery 100 of this embodiment has a composite 10 that functions as a positive electrode, a negative electrode 30 provided in contact with one surface of the composite 10, a current collector 41 provided in contact with a surface of the composite 10 opposite to the surface in contact with the negative electrode 30, and a current collector 42 provided in contact with a surface of the negative electrode 30 opposite to the surface in contact with the composite 10. In other words, the lithium ion battery 100 of this embodiment has a configuration in which the current collector 41, the composite 10, the negative electrode 30, and the current collector 42 are laminated in this order.

[0150] The shape of the lithium ion battery 100 is not particularly limited and may be, for example, a polygonal disk shape, but in the illustrated configuration, it is disk-shaped. The size of the lithium ion battery 100 is not particularly limited, but for example, the diameter of the lithium ion battery 100 is, for example, 10 mm or more and 20 mm or less, and the thickness of the lithium ion battery 100 is, for example, 0.1 mm or more and 1.0 mm or less.

[0151] The lithium ion battery 100 is thus small and thin, and, combined with being chargeable and dischargeable and being all-solid-state, can be suitably used as a power source for mobile information terminals such as smartphones. As will be described later, the lithium ion battery 100 may be used for purposes other than as a power source for mobile information terminals.

[0152] [4-1] Complex The composite 10 includes a positive electrode active material and the solid electrolyte of the present invention described above. In other words, the composite 10 has an active material part P5 made of a positive electrode active material, which is a type of active material, and a first electrolyte part P3 made of a first electrolyte P3'. In particular, it is preferable that the composite 10 satisfies the condition explained in [3] above.

[0153] The active material constituting the composite 10, that is, the positive electrode active material in this embodiment, is preferably a positive electrode active material containing Li and O. This makes it a lithium ion supply source and allows it to release and receive lithium ions.

[0154] Examples of the positive electrode active material contained in the composite 10 include those exemplified in [3] above.

[0155] The composite 10 may contain a positive electrode active material and the above-described solid electrolyte of the present invention, i.e., the solid electrolyte represented by the above composition formula (1), but may further contain another solid electrolyte.

[0156] Such a solid electrolyte includes a second electrolyte containing Li, B, O, and the like. Such a second electrolyte preferably satisfies the conditions explained in [2-2-2] above.

[0157] The thickness of the composite 10 is not particularly limited, but is preferably 0.1 μm or more and 500 μm or less, and more preferably 0.3 μm or more and 100 μm or less.

[0158] [4-2] Negative electrode Negative electrode 30 may be any material so long as it is made of a so-called negative electrode active material that repeatedly electrochemically absorbs and releases lithium ions at a potential lower than that of the material selected as the positive electrode active material that constitutes composite 10.

[0159] The negative electrode 30 is made of a material containing a negative electrode active material. As the negative electrode active material constituting the negative electrode 30, for example, those exemplified in the above [3] can be used.

[0160] In particular, the negative electrode 30, which is an electrode, is preferably made of metallic Li. This has the effect of storing approximately 10 times the amount of electricity per weight and several times the amount per volume compared to the carbon anodes commonly used in lithium-ion batteries.

[0161] The thickness of the negative electrode 30 is not particularly limited, but is preferably 0.1 μm or more and 500 μm or less, and more preferably 0.3 μm or more and 100 μm or less.

[0162] Examples of methods for forming the negative electrode 30 include vapor deposition methods such as vacuum deposition, sputtering, CVD, PLD, ALD, and aerosol deposition, and chemical deposition methods using a solution such as the sol-gel method and MOD method. In addition, for example, fine particles of the negative electrode active material may be slurried together with an appropriate binder, and a coating film may be formed by performing squeegee or screen printing, and the coating film may be dried and fired to bake it onto the surface of the composite 10.

[0163] [4-3] Current collector The current collectors 41 and 42 are conductors provided to transfer electrons to and from the composite 10 as the positive electrode or the negative electrode 30. The current collectors 41 and 42 are usually made of a material that has a sufficiently small electrical resistance and whose electrical conductivity characteristics and mechanical structure do not substantially change due to charging and discharging.

[0164] Examples of the constituent material of the current collectors 41, 42 include one metal selected from the group consisting of Cu, Mg, Ti, Fe, Co, Ni, Zn, Al, Ge, In, Au, Pt, Ag, and Pd, and an alloy containing two or more metals selected from the group. In particular, the constituent material of the current collectors 41 and 42 is preferably Cu.

[0165] The current collectors 41, 42 are usually provided so as to reduce the contact resistance with the composite 10 and the negative electrode 30, respectively. Examples of the shape of the current collectors 41, 42 include a plate shape, a mesh shape, and the like.

[0166] The thickness of the current collectors 41 and 42 is not particularly limited, but is preferably 7 μm or more and 85 μm or less, and more preferably 10 μm or more and 60 μm or less.

[0167] The lithium ion battery 100 does not necessarily have to include the pair of current collectors 41, 42, and it is sufficient if the lithium ion battery 100 includes one of the pair of current collectors 41, 42.

[0168] For example, when a plurality of lithium ion batteries 100 are stacked and electrically connected in series, the lithium ion battery 100 may be configured to include only the current collector 41 of the pair of current collectors 41, .

[0169] [5] Battery manufacturing method Next, a method for producing a battery according to the present invention will be described.

[0170] [5-1] Manufacturing method of the battery of the first embodiment The method for manufacturing the battery according to the first embodiment will be described below.

[0171] FIG. 4 is a flowchart showing the method for manufacturing the battery of the first embodiment, and FIGS. 5 and 6 are vertical cross-sectional views that typically show the method for manufacturing the battery of the first embodiment.

[0172] 4 to 6, the method for producing a battery according to the present embodiment includes the following steps: a first mixing step (3A) of dissolving a plurality of kinds of raw materials containing metal elements constituting the lithium composite metal oxide represented by the above composition formula (1) in a solvent and mixing them to obtain a first mixture P1, a first compact formation step (3B) of forming a first compact Q1 using an active material, a composite formation step (3C) of impregnating the first compact Q1 with the first mixture P1 and subjecting it to a heat treatment to form a composite 10 including a first electrolyte part P3 composed of a crystalline first electrolyte P3' and an active material part P5 composed of an active material, an electrode formation step (3D) of forming a negative electrode 30 as an electrode on one side of the composite 10, and a current collector formation step (3E) of forming a current collector 41 on the other side of the composite 10.

[0173] This makes it possible to provide a method for producing a battery equipped with a solid electrolyte that can favorably maintain a high total ion conductivity even in the atmosphere.

[0174] [5-1-1] First mixing step In the first mixing step, a plurality of raw materials containing metal elements constituting the lithium composite metallic oxide represented by the above composition formula (1) are dissolved in a solvent and mixed to obtain a first mixture P1.

[0175] This step is preferably carried out by the same method and under the same conditions as described in [2-1-1] above. However, in this embodiment, a solvent is used to prepare the first mixture P1 in the first mixing step.

[0176] [5-1-2] First molded body forming step In the first compact formation step, a first compact Q1 is formed using an active material.

[0177] The method for forming the first compact Q1 is not particularly limited, but may be, for example, powder compaction.

[0178] To form the first compact Q1, for example, the active materials exemplified in the above item [3], in particular the positive electrode active materials, can be suitably used.

[0179] [5-1-3] Complex formation step In the composite formation step, the first mixture P1 is impregnated into a first compact Q1 and then heat-treated to form a composite 10 including a crystalline first electrolyte portion P3 and an active material portion P5.

[0180] As a method for impregnating the first mixture P1 into the first compact Q1, for example, a dipping method can be suitably adopted.

[0181] The heat treatment in this step can be carried out, for example, by the same method and under the same conditions as described in [2-1-3] above. However, it is preferable to carry out a first heat treatment by the same method and under the same conditions as described in [2-1-2] above, followed by a second heat treatment by the same method and under the same conditions as described in [2-1-3] above.

[0182] More specifically, the heat treatment in this step preferably includes a first heat treatment having a heating temperature of 500°C or more and 650°C or less, and a second heat treatment performed after the first heat treatment having a heating temperature of 800°C or more and 1000°C or less. This provides the same effect as described above.

[0183] [5-1-4] Electrode formation process In the electrode formation step, a negative electrode 30 which is an electrode is formed on one side of the composite 10 .

[0184] The method for forming the negative electrode 30 is not particularly limited, but may be, for example, a vapor phase film formation method using a vacuum deposition apparatus or the like.

[0185] [5-1-5] Current collector formation process In the current collector formation step, a current collector 41 is formed on the other side of the composite 10, that is, on the surface of the composite 10 opposite to the surface on which the negative electrode 30 is provided.

[0186] In this embodiment, a current collector 41 is formed on the other side of the composite 10, and a current collector 42 is formed on the surface of the negative electrode 30 opposite to the surface in contact with the composite 10.

[0187] The current collectors 41, 42 can be formed, for example, by pressing and bonding a metal foil such as aluminum foil or copper foil cut into a circular shape by die cutting or the like onto a target portion of the composite 10 or the negative electrode, respectively.

[0188] [5-2] Manufacturing method of the battery according to the second embodiment Next, a method for manufacturing a battery according to the second embodiment will be described.

[0189] FIG. 7 is a flowchart showing the method for manufacturing the battery of the second embodiment, and FIGS. 8 and 9 are vertical cross-sectional views that typically show the method for manufacturing the battery of the second embodiment.

[0190] Hereinafter, the method for manufacturing a battery according to the second embodiment will be described with reference to these drawings. The differences from the embodiment described above will be mainly described, and a description of the similar points will be omitted.

[0191] 7 to 9, the method for producing a battery according to this embodiment includes the following steps: a first mixing step (4A) of dissolving in a solvent a plurality of raw materials containing metal elements constituting the lithium composite metal oxide represented by the above composition formula (1) and mixing them to obtain a first mixture P1, a first compact formation step (4B) of forming a first compact Q1 using an active material, a second compact formation step (4C) of impregnating the first compact Q1 with the first mixture P1 and subjecting it to a heat treatment to form a second compact Q3 including a first electrolyte part P3 made of a crystalline first electrolyte P3' and an active material part P5 made of an active material, and a second electrolyte P4', particularly The method includes a composite formation step (4D) of melting the second electrolyte P4' while contacting the first electrolyte P4 with a second electrolyte P4' containing Li, B and O, filling the second compact Q3 with the molten liquid of the second electrolyte P4', and then cooling the second compact Q3 filled with the molten liquid of the second electrolyte P4' to form a composite 10 including the first electrolyte part P3, the second electrolyte part P4 composed of the second electrolyte P4', and the active material part P5, an electrode formation step (4E) of forming a negative electrode 30 as an electrode on one side of the composite 10, and a current collector formation step (4F) of forming a current collector 41 on the other side of the composite 10.

[0192] This makes it possible to provide a method for producing a battery equipped with a solid electrolyte that can favorably maintain a high total ion conductivity even in the atmosphere.

[0193] [5-2-1] First mixing step In the first mixing step, a plurality of raw materials containing metal elements constituting the lithium composite metallic oxide represented by the above composition formula (1) are dissolved in a solvent and mixed to obtain a first mixture P1. This step can be carried out by the same method and under the same conditions as described in [5-1-1] above.

[0194] [5-2-2] First molded body forming step In the first compact formation step, a first compact Q1 is formed using an active material. This step can be carried out by the same method and under the same conditions as described in [5-1-2] above.

[0195] [5-2-3] Second compact forming step In the second compact formation process, the first mixture P1 is impregnated into the first compact Q1 and then subjected to a heat treatment to form a second compact Q3 including a first electrolyte portion P3 composed of a crystalline first electrolyte P3' and an active material portion P5 composed of an active material. This step can be carried out by the same method and under the same conditions as described in [5-1-3] above.

[0196] [5-2-4] Complex formation step In the complex formation process, the second electrolyte P4' is melted while being in contact with the second compact Q3, and the molten liquid of the second electrolyte P4' is filled into the second compact Q3. Thereafter, the second compact Q3 filled with the molten liquid of the second electrolyte P4' is cooled to form a complex 10 including the first electrolyte portion P3, the second electrolyte portion P4 and the active material portion P5. This step can be carried out by the same method and under the same conditions as described in [2-2-2] above.

[0197] [5-2-5] Electrode formation process In the electrode formation step, a negative electrode 30 which is an electrode is formed on one side of the composite 10 . This step can be carried out by the same method and under the same conditions as described in [5-1-4] above.

[0198] [5-2-6] Current collector formation process In the current collector formation step, a current collector 41 is formed on the other side of the composite 10, that is, on the surface of the composite 10 opposite to the surface on which the negative electrode 30 is provided.

[0199] In this embodiment, a current collector 41 is formed on the other side of the composite 10, and a current collector 42 is formed on the surface of the negative electrode 30 opposite to the surface in contact with the composite 10. This step can be carried out by the same method and under the same conditions as described in [5-1-5] above.

[0200] [5-3] Manufacturing method of the battery of the third embodiment Next, a method for manufacturing a battery according to the third embodiment will be described.

[0201] FIG. 10 is a flow chart showing a method for manufacturing a battery of the third embodiment, and FIGS. 11, 12, and 13 are vertical cross-sectional views typically showing the method for manufacturing a battery of the third embodiment.

[0202] Hereinafter, the method for manufacturing a battery according to the third embodiment will be described with reference to these drawings. The differences from the above-described embodiment will be mainly described, and a description of the similar points will be omitted.

[0203] 10 to 13, the method for producing a battery according to the present embodiment includes the following steps: a first mixing step (5A) of mixing a plurality of raw materials containing metal elements constituting the lithium composite metal oxide represented by the composition formula (1) to obtain a first mixture P1, a pre-calcined body forming step (5B) of subjecting the first mixture P1 to a first heat treatment to obtain a pre-calcined body P2, a second mixing step (5C) of mixing the pre-calcined body P2 with an active material to obtain a second mixture Q6, a third compact forming step (5D) of molding the second mixture Q6 to form a third compact Q7, a composite forming step (5E) of subjecting the third compact Q7 to a second heat treatment to form a composite 10 including a crystalline first electrolyte portion P3 and an active material portion P5 composed of an active material, an electrode forming step (5F) of forming a negative electrode 30 as an electrode on one side of the composite 10, and a current collector forming step (5G) of forming a current collector 41 on the other side of the composite 10.

[0204] This makes it possible to provide a method for producing a battery equipped with a solid electrolyte that can favorably maintain a high total ion conductivity even in the atmosphere.

[0205] [5-3-1] First mixing step In the first mixing step, a plurality of raw materials containing metal elements constituting the lithium composite metal oxide represented by the above composition formula (1) are mixed to obtain a first mixture P1.

[0206] This step can be carried out by the same method and under the same conditions as described in [5-1-1] above. However, in this embodiment, it is preferable not to use a solvent in this step.

[0207] [5-3-2] Pre-sintered body formation process In the calcined body forming step, the first mixture P1 is subjected to a first heat treatment to obtain a calcined body P2. This step can be carried out by the same method and under the same conditions as described in [2-1-2] above.

[0208] In particular, the heating temperature in the first heat treatment is preferably 500°C or higher and 650°C or lower, more preferably 510°C or higher and 650°C or lower, and even more preferably 520°C or higher and 600°C or lower.

[0209] This makes it possible to more effectively prevent the metal elements constituting the first electrolyte section P3 from unintentionally evaporating, in particular Li, which is easily volatile among metal materials, and thus allows for more precise control of the composition of the first electrolyte section P3 and makes it possible to manufacture the lithium-ion battery 100 more efficiently.

[0210] [5-3-3] Second mixing step In the second mixing step, the pre-sintered body P2 and an active material are mixed to obtain a second mixture Q6.

[0211] This process can be carried out in the same manner and under the same conditions as described in [2-1-1] above, except that the pre-sintered body P2 and the active material are used instead of the multiple raw materials containing the metal elements included in the composition formula (1) above.

[0212] [5-3-4] Third molded body forming step In the third compact formation step, the second mixture Q6 is molded to form a third compact Q7.

[0213] This step can be carried out in the same manner and under the same conditions as described in [5-1-2] above, except that the second mixture Q6 is used instead of the active material.

[0214] [5-3-5] Complex formation step In the composite formation step, the third compact Q7 is subjected to a second heat treatment to form a composite 10 including the first electrolyte part P3 and the active material part P5.

[0215] This step is preferably carried out by the same method and under the same conditions as those described in the above [2-1-3]. This provides the same effect as described above.

[0216] In particular, the heating temperature in the second heat treatment is preferably 800°C or higher and 1000°C or lower, more preferably 800°C or higher and 950°C or lower, and even more preferably 800°C or higher and 900°C or lower.

[0217] This allows the first electrolyte portion P3 having desired characteristics to be stably formed by heat treatment at a relatively low temperature for a relatively short time. In addition, since the first electrolyte portion P3 can be formed by heat treatment at a relatively low temperature for a relatively short time, the productivity of the lithium ion battery 100 can be improved, for example, and this is also preferable from the viewpoint of energy saving.

[0218] [5-3-6] Electrode formation process In the electrode formation step, a negative electrode 30 which is an electrode is formed on one side of the composite 10 . This step can be carried out by the same method and under the same conditions as described in [5-1-4] above.

[0219] [5-3-7] Current collector formation process In the current collector formation step, a current collector 41 is formed on the other side of the composite 10, that is, on the surface of the composite 10 opposite to the surface on which the negative electrode 30 is provided.

[0220] In this embodiment, a current collector 41 is formed on the other side of the composite 10, and a current collector 42 is formed on the surface of the negative electrode 30 opposite to the surface in contact with the composite 10. This step can be carried out by the same method and under the same conditions as described in [5-1-5] above.

[0221] [5-4] Manufacturing method of the battery according to the fourth embodiment Next, a method for manufacturing a battery according to the fourth embodiment will be described.

[0222] FIG. 14 is a flowchart showing a method for manufacturing a battery of the fourth embodiment, and FIGS. 15, 16, and 17 are vertical cross-sectional views typically showing the method for manufacturing a battery of the fourth embodiment.

[0223] Hereinafter, the method for manufacturing a battery according to the fourth embodiment will be described with reference to these figures. The differences from the above-described embodiment will be mainly described, and a description of the similar points will be omitted.

[0224] 14 to 17, the method for producing a battery of this embodiment includes the following steps: a first mixing step (6A) of mixing a plurality of kinds of raw materials containing metal elements constituting the lithium composite metal oxide represented by the above composition formula (1) to obtain a first mixture P1, a pre-sintered body forming step (6B) of performing a first heat treatment on the first mixture P1 to obtain a pre-sintered body P2, a second mixing step (6C) of mixing the pre-sintered body P2 with an active material to obtain a second mixture Q6, a third compact forming step (6D) of molding the second mixture Q6 to form a third compact Q7, and a second heat treatment on the third compact Q7 to form a second compact Q3 including a first electrolyte portion P3 composed of a crystalline first electrolyte P3′ and an active material portion P5 composed of an active material. The method includes a compact formation step (6E), a composite formation step (6F) of melting a second electrolyte P4', in a state in which the second electrolyte P4', particularly the second electrolyte P4' containing Li, B and O, is brought into contact with the second compact Q3, filling the second compact Q3 with the molten liquid of the second electrolyte P4', and then cooling the second compact Q3 filled with the molten liquid of the second electrolyte P4' to form a composite 10 including the first electrolyte portion P3, the second electrolyte portion P4 composed of the second electrolyte P4', and an active material portion P5, an electrode formation step (6G) of forming a negative electrode 30, which is an electrode, on one side of the composite 10, and a current collector formation step (6H) of forming a current collector 41 on the other side of the composite 10.

[0225] This makes it possible to provide a method for producing a battery equipped with a solid electrolyte that can favorably maintain a high total ion conductivity even in the atmosphere.

[0226] [5-4-1] First mixing step In the first mixing step, a plurality of raw materials containing metal elements constituting the lithium composite metal oxide represented by the above composition formula (1) are mixed to obtain a first mixture P1.

[0227] This step can be carried out by the same method and under the same conditions as described in [5-3-1] above. However, in this embodiment, it is preferable not to use a solvent in this step.

[0228] [5-4-2] Pre-sintered body formation process In the calcined body forming step, the first mixture P1 is subjected to a first heat treatment to obtain a calcined body P2. This step can be carried out by the same method and under the same conditions as described in [5-3-2] above.

[0229] [5-4-3] Second mixing step In the second mixing step, the pre-sintered body P2 and an active material are mixed to obtain a second mixture Q6. This step can be carried out by the same method and under the same conditions as described in [5-3-3] above.

[0230] [5-4-4] Third molded body forming step In the third compact formation step, the second mixture Q6 is molded to form a third compact Q7. This step can be carried out by the same method and under the same conditions as described in [5-3-4] above.

[0231] [5-4-5] Second compact forming step In the second compact formation step, the third compact Q7 is subjected to a second heat treatment to form a second compact Q3 including a first electrolyte portion P3 and an active material portion P5. This step can be carried out by the same method and under the same conditions as described in [5-3-5] above.

[0232] [5-4-6] Complex formation step In the complex formation process, the second electrolyte P4' is melted while being in contact with the second compact Q3, and the molten liquid of the second electrolyte P4' is filled into the second compact Q3. Thereafter, the second compact Q3 filled with the molten liquid of the second electrolyte P4' is cooled to form a complex 10 including the first electrolyte portion P3, the second electrolyte portion P4 and the active material portion P5. This step can be carried out by the same method and under the same conditions as described in [5-2-4] above.

[0233] [5-4-7] Electrode formation process In the electrode formation step, a negative electrode 30 which is an electrode is formed on one side of the composite 10 . This step can be carried out by the same method and under the same conditions as described in [5-1-4] above.

[0234] [5-4-8] Current collector formation process In the current collector formation step, a current collector 41 is formed on the other side of the composite 10, that is, on the surface of the composite 10 opposite to the surface on which the negative electrode 30 is provided.

[0235] In this embodiment, a current collector 41 is formed on the other side of the composite 10, and a current collector 42 is formed on the surface of the negative electrode 30 opposite to the surface in contact with the composite 10. This step can be carried out by the same method and under the same conditions as described in [5-1-5] above.

[0236] [6]Electronic equipment Next, an electronic device according to the present invention will be described.

[0237] An electronic device according to the present invention includes the battery according to the present invention described above. This makes it possible to provide an electronic device equipped with a battery including a solid electrolyte that can favorably maintain a high total ion conductivity even in the atmosphere.

[0238] Examples of electronic devices include personal computers, digital cameras, mobile phones, smartphones, music players, tablet terminals, watches, smart watches, various printers such as inkjet printers, televisions, projectors, head-up displays, wireless headphones, wireless earphones, smart glasses, wearable devices such as head-mounted displays, video cameras, video tape recorders, car navigation devices, drive recorders, pagers, electronic notebooks, electronic dictionaries, electronic translators, calculators, electronic game devices, toys, word processors, workstations, robots, videophones, security television monitors, electronic binoculars, POS terminals, medical devices, fish finders, various measuring devices, mobile terminal base station devices, various instruments such as vehicles, railroad cars, aircraft, helicopters, and ships, flight simulators, and network servers. The lithium ion battery 100 may also be applied to moving bodies such as automobiles and ships. More specifically, the lithium ion battery 100 can be suitably applied as a storage battery for electric vehicles, plug-in hybrid vehicles, hybrid vehicles, fuel cell vehicles, and the like. The lithium ion battery 100 can also be applied to, for example, household power sources, industrial power sources, and solar power generation storage batteries.

[0239] Hereinafter, a wearable device will be described as a specific example of an electronic device according to the present invention. FIG. 18 is a perspective view showing a configuration of a wearable device as an electronic device.

[0240] As shown in FIG. 18, a wearable device 300 as an electronic device is an information device that is worn on the human body, for example on the wrist WR, like a wristwatch and can obtain information related to the human body, and is equipped with a band 301, a sensor 302, a display unit 303, a processing unit 304, and a lithium ion battery 100.

[0241] The band 301 is in the form of a strip made of flexible resin such as rubber so that it fits closely around the wrist WR when worn, and has a joining portion at one end of the strip that allows the joining position to be adjusted.

[0242] The sensor 302 is, for example, an optical sensor, and is arranged on the inner surface side of the band 301, that is, on the wrist WR side, so as to come into contact with the wrist WR when worn.

[0243] The display unit 303 is, for example, a light-receiving type liquid crystal display device, and is arranged on the outer surface of the band 301, i.e., on the opposite side to the inner surface on which the sensor 302 is attached, so that the wearer can read the information displayed on the display unit 303.

[0244] The processing unit 304 is, for example, an integrated circuit, which is built into the band 301 and is electrically connected to the sensor 302 and the display unit 303. The processing unit 304 performs calculations for measuring the pulse rate, blood glucose level, etc. based on the output from the sensor 302. It also controls the display unit 303 to display the measurement results, etc.

[0245] The lithium ion battery 100 is detachably mounted in the band 301 and serves as a power supply source for supplying power to the sensor 302, the display unit 303, the processing unit 304, and the like.

[0246] According to the wearable device 300 of this embodiment, the sensor 302 electrically detects information related to the wearer's pulse rate and blood glucose level from the wrist WR, and after arithmetic processing in the processing unit 304, the pulse rate, blood glucose level, etc. can be displayed on the display unit 303. The display unit 303 can display not only the measurement results, but also information indicating the state of the human body predicted from the measurement results, the time, etc.

[0247] In addition, because the lithium ion battery 100 used is small yet has excellent charge / discharge characteristics, it is possible to provide a wearable device 300 that is lightweight, thin, and able to withstand repeated use over a long period of time. In addition, because the lithium ion battery 100 is a solid-state secondary battery, it is possible to provide a wearable device 300 that can be used repeatedly by charging, and that can be used safely for a long period of time without worrying about leakage of electrolyte or the like.

[0248] In this embodiment, a wristwatch-type wearable device 300 is exemplified, but the wearable device 300 may be worn on the ankle, head, ear, waist, or the like, for example.

[0249] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these.

[0250] For example, the solid electrolyte of the present invention is not limited to those produced by the above-mentioned method, and may be produced by any method as long as it is represented by the above composition formula (1).

[0251] More specifically, the solid electrolyte of the present invention may be produced, for example, by a method having other steps in addition to the steps described above, or may be produced by a method in which the order of the steps described above is changed.

[0252] Furthermore, the battery according to the present invention may be any battery including the solid electrolyte of the present invention, and is not limited to the embodiment described above.

[0253] For example, the battery according to the embodiment described above includes a composite containing the solid electrolyte of the present invention and an active material, an electrode provided on one surface of the composite, and a current collector provided on the other surface of the composite. However, a solid electrolyte layer not containing an active material may be provided between the composite and the electrode.

[0254] In addition, in the above-described embodiment, a case has been described as a representative example in which the composite constituting the battery contains a positive electrode active material as an active material, and the electrode is a negative electrode. However, the composite constituting the battery may contain a negative electrode active material as an active material, and the electrode may be a positive electrode. EXAMPLES

[0255] Next, specific examples of the present invention will be described. In the following description, room temperature refers to 25°C and 1 atm. Furthermore, treatments and measurements for which no particular temperature conditions are specified were performed at 25°C, and treatments and measurements for which no particular pressure conditions are specified were performed in an environment of 1 atm.

[0256] [7] Production of solid electrolytes by solid-phase method Example 1 First, the raw material powder is Li 2 O (99% purity, manufactured by Kojundo Kagaku Kenkyusho Co., Ltd.), Ga 2 O 3 (Purity 99.99%, Fujifilm Wako Pure Chemical Industries, Ltd.), La 2 O 3 (Purity 99.99%, Fujifilm Wako Pure Chemical Industries, Ltd.), ZrO 2 (Special grade, Fujifilm Wako Pure Chemical Industries, Ltd.), Nd 2 O 3 (Purity 99.9%, Fujifilm Wako Pure Chemical Industries, Ltd.), Y 2 O 3 Powders of CaO (purity 99.99%, manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.), CaO (purity 99.9%, manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.), and SrO (purity 99.5%, manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) were prepared.

[0257] These raw powders were each ground using a planetary ball mill (PL-7 Premium Line, Fritsch) at 1000 rpm for 1 hour, and then ground at 500 rpm for 1 hour. A zirconia pot, 60 g of zirconia balls (diameter 2 mm), and ethanol were used for the planetary ball milling. After the grounding process, each raw powder was collected by suction filtration.

[0258] Thereafter, each of the pulverized raw material powders was subjected to a drying treatment under the following temperature conditions: heating rate: 900°C / hour, holding temperature: 900°C, holding time at 900°C: 12 hours.

[0259] The powders of the raw materials that had been crushed and dried were weighed in a predetermined ratio and dry-mixed in an automatic mortar (ANM1000, manufactured by Nitto Kagaku Co., Ltd.) for 1 hour to obtain a mixed powder. At this time, Li was added so that the ratio of Li was 20 mass% in excess of the composition of the target solid electrolyte. 2 O was used. 2 The raw material powders other than O were used in such proportions that the corresponding metal elements would form the composition of the intended solid electrolyte.

[0260] The mixed powder was placed in an alumina crucible, covered with an alumina lid, and pre-fired in an electric furnace FO100 manufactured by Yamato Scientific Co., Ltd. to obtain a pre-fired body. The heating rate was 900°C / hour, the holding temperature was 900°C, and the holding time at 900°C was 12 hours.

[0261] After the electric furnace was cooled to room temperature, the calcined body was removed from the crucible. The cooling rate to 500°C was 400°C / hour, and then the crucible was left to cool. The mixed powder was placed in the electric furnace and the calcined body was removed from the electric furnace in a dry room with low moisture concentration.

[0262] The calcined body was ground and mixed for 1 hour in an automatic mortar (ANM1000, manufactured by Nitto Kagaku Co., Ltd.). 0.200 g of the ground calcined body thus obtained was weighed out and filled into a carbide die with an inner diameter of 10 mm as a mold, and the ground and mixed powder was compression molded into pellets with a diameter of 10 mm under a load of 90 kN using a uniaxial pressing machine (100 kN Newton press, manufactured by NPa Systems Co., Ltd.). After that, CIP molding was performed using a cold isostatic pressing machine (Press-CIP, manufactured by NPa Systems Co., Ltd.) to produce calcined body pellets, which are disk-shaped molded products. CIP molding was performed by pressing at a pressure of 300 MPa for 10 minutes.

[0263] Thereafter, the entire pre-sintered pellets were covered with a protective powder having the same composition as the pre-sintered pellets, and the protective powder was filled into an alumina crucible. The protective powder had the same mass as the pre-sintered pellets, 0.200 g.

[0264] Thereafter, the crucible was covered with an alumina lid, and the mixture was subjected to main firing in an electric furnace FO100 manufactured by Yamato Scientific Co., Ltd. The heating rate was 900°C / hour, the holding temperature was 1000°C, and the holding time at 1000°C was 10 hours.

[0265] After the electric furnace was cooled to room temperature, a disk-shaped solid electrolyte with a diameter of about 9.5 mm and a thickness of about 600 μm was taken out from the crucible. The cooling rate to 500° C. was 500° C. / hour, and the electrolyte was then allowed to cool naturally.

[0266] The mixing of raw materials, crushing of the fired powder, and molding were all carried out in a dry room with dew point control (-40°C).

[0267] The solid electrolyte thus obtained was confirmed by XRD measurement to be a single phase cubic garnet crystal without any impurity phase.

[0268] The composition of the obtained solid electrolyte was Li 6.25 Ga 0.85 / 3 La 2.8 Nd 0.05 Y 0.05 Ca 0.05 Sr 0.05 Zr 2 O 12 It was.

[0269] (Examples 2 to 7) A solid electrolyte was produced in the same manner as in Example 1, except that the amounts of raw material powders used were adjusted so that the composition of the solid electrolyte was as shown in FIG.

[0270] In addition, Rb 2 CO 3 The fluorine-containing fluoride used was manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. and had a purity of 97.0+%.

[0271] (Comparative Examples 1 to 4) A solid electrolyte was produced in the same manner as in Example 1, except that the types and amounts of raw material powders were adjusted so that the composition of the solid electrolyte was as shown in FIG. The BaO used was manufactured by Merck and had a purity of 99.99%.

[0272] The compositions and crystal phases of the solid electrolytes of Examples 1 to 7 and Comparative Examples 1 to 4 are summarized in Figure 19. The crystal phases of the solid electrolytes were identified from X-ray diffraction patterns obtained by measurement using an X-ray diffractometer X'Pert-PRO manufactured by Philips.

[0273] [8] Evaluation of solid electrolytes obtained using the solid-phase method [8-1] Bulk resistance, grain boundary resistance, and total resistance of solid electrolytes For the disk-shaped solid electrolytes of Examples 1 to 7 and Comparative Examples 1 to 4 immediately after production, the bulk resistance Rb [Ω], grain boundary resistance Rgb [Ω], and total resistance Rb+Rgb [Ω] were determined as follows.

[0274] The electrochemical properties of the disk-shaped solid electrolyte were evaluated by Nyquist plot measurement using the AC impedance method. Both sides of the disk-shaped solid electrolyte were polished with abrasive paper (#400, #1000) until gloss appeared. The thickness of the molded body was measured with a micrometer. The oxide layer on the surface of the Li foil was removed with a glass plate, and a Li metal foil (thickness 20 μm, manufactured by Honjo Metals) punched into a circle with a diameter of 8 mm was attached to the disk-shaped solid electrolyte, and then the product was pressurized for 5 minutes at 300 MPa using a cold isostatic pressing machine (NPa system, Press-CIP) to produce a non-blocking symmetrical cell. The molded sample was then fixed in a sealed cell for a high-frequency impedance measuring device manufactured by Toyo Corporation. Note that the process from polishing the disk-shaped solid electrolyte to placing it in the evaluation cell was carried out in an Ar atmosphere glove box (manufactured by Miwa Manufacturing Co., Ltd., MDB-2LKP-OSSI type) to prevent exposure to the atmosphere. The samples in the evaluation cell were subjected to impedance measurement using an electrochemical measurement system (high frequency impedance measurement device manufactured by Toyo Corporation) at a frequency range of 100MHz to 2Hz, an amplitude of 10mV, and a temperature of 25°C. A frequency analysis was performed from the results, and the resistance was separated into three resistance components: bulk resistance, grain boundary resistance, and interface resistance, to obtain the bulk resistance Rb and grain boundary resistance Rgb. In addition, the total resistance Rb+Rgb [Ω] was calculated from these results.

[0275] In addition, the ratio of the grain boundary resistance to the resistance component of the solid electrolyte, Rb+Rgb [Ω], was calculated as Rratio=Rgb / (Rb+Rgb).

[0276] [8-2] Lithium ion conductivity For the disk-shaped solid electrolytes of Examples 1 to 7 and Comparative Examples 1 to 4, the lithium ion conductivity was determined as follows immediately after production.

[0277] That is, the lithium ion conductivity was calculated by calculating the resistivity ρ from the relationship (Rb+Rgb)=ρ×(l / A) using the resistance component of the solid electrolyte, Rb+Rgb [Ω], the disk thickness l, and the electrode area A, and then converting the reciprocal of this resistance value into the lithium ion conductivity.

[0278] [8-3] Lattice constant Immediately after production, the lattice constants of the disk-shaped solid electrolytes of Examples 1 to 7 and Comparative Examples 1 to 4 were determined by X-ray diffraction (XRD). These results are summarized in FIG.

[0279] As is clear from FIG. 20, excellent results were obtained in all of Examples 1 to 7, which are solid electrolytes represented by the above composition formula (1), whereas only poor results were obtained in Comparative Examples 1 to 4.

[0280] In addition, for the disk-shaped solid electrolytes of Examples 1 to 7 and Comparative Examples 1 to 4, the bulk resistance Rb [Ω], grain boundary resistance Rgb [Ω], total resistance Rb + Rgb [Ω], Rratio, and lithium ion conductivity were measured in the same manner as above after the solid electrolytes were left in an air atmosphere for 24 hours after production. As a result, it was confirmed that the present invention can obtain excellent results.

[0281] [9] Production of solid electrolytes using the liquid phase method (method using precursor solutions) [9-1] Preparation of precursor solution (Preparation example A1) First, raw materials were prepared as the source of each metal element, Li, Ga, La, Rb, Ca, Sr, Nd, Y, Zr, Nb, Sb, Ta, Ce and Sn, and mixed with the following solvents, i.e., 2-n-butoxyethanol (Kanto Chemical Co., Ltd., special grade), 2-methoxyethanol or ethyl alcohol, in a given ratio to obtain raw material solutions, which are solutions of the raw material of each metal element source. The raw material solutions containing the elements of the raw materials used in the production of the solid electrolytes of Examples 8 to 14 and Comparative Examples 5 to 10 are shown below.

[0282] [2mol / kg lithium nitrate in 2-n-butoxyethanol] 2.7578 g of lithium nitrate (3N5, Kanto Chemical Co., Ltd.) with a purity of 99.95% and 17.2420 g of 2-n-butoxyethanol (ethylene glycol monobutyl ether) (special grade, deer) were weighed into a 30 g Pyrex (registered trademark of Corning Co., Ltd.) reagent bottle containing a magnetic stirrer bar. The reagent bottle was then placed on a magnetic stirrer with a hot plate function, and the lithium nitrate was completely dissolved in the 2-n-butoxyethanol while stirring at 190°C for 1 hour, and the mixture was gradually cooled to room temperature to obtain a 2-n-butoxyethanol solution of lithium nitrate with a concentration of 2 mol / kg. The purity of lithium nitrate can be measured using an ion chromatography mass spectrometer.

[0283] [1 mol / kg gallium nitrate solution in ethyl alcohol] 3.5470g of gallium nitrate n-hydrate (n=5.5) manufactured by Kojundo Chemical Laboratory and 6.4530g of ethyl alcohol that had been dehydrated in advance were weighed into a 20g Pyrex reagent bottle containing a magnetic stirrer. The bottle was then placed on a hot plate equipped with a magnetic stirrer and stirred at 90°C for 1 hour to completely dissolve the gallium nitrate n-hydrate (n=5.5) in the ethyl alcohol. The bottle was then cooled slowly to room temperature to obtain an ethyl alcohol solution of gallium nitrate with a concentration of 1mol / kg. The hydration number n of the gallium nitrate n-hydrate used was 5.5 based on the results of the mass loss in a combustion experiment (differential thermal analysis).

[0284] [1 mol / kg lanthanum nitrate solution in 2-n-butoxyethanol] Lanthanum nitrate hexahydrate (Kanto Chemical, 4N, 8.6608 g) and 2-n-butoxyethanol (11.3392 g) were weighed into a 30 g Pyrex reagent bottle containing a magnetic stir bar. The bottle was then placed on a magnetic stirrer with a hot plate function and stirred at 140°C for 30 minutes to completely dissolve lanthanum nitrate hexahydrate in 2-n-butoxyethanol. The bottle was then gradually cooled to room temperature to obtain a 1 mol / kg lanthanum nitrate in 2-n-butoxyethanol solution.

[0285] [1 mol / kg solution of rubidium isopropoxide in 2-n-butoxyethanol] 1.4456 g of rubidium isopropoxide manufactured by Kojundo Chemical Laboratory Co., Ltd. and 8.5544 g of 2-n-butoxyethanol that had been previously dehydrated were weighed into a 20 g Pyrex reagent bottle containing a magnetic stirrer. The reagent bottle was then placed on a hot plate equipped with a magnetic stirrer and stirred at room temperature for 30 minutes to completely dissolve the rubidium isopropoxide in the 2-n-butoxyethanol, yielding a 1 mol / kg solution of rubidium isopropoxide in 2-n-butoxyethanol.

[0286] [0.5mol / kg concentration of strontium isopropoxide in 2-methoxyethanol] 1.0290 g of strontium isopropoxide manufactured by Sigma-Aldrich and 8.9711 g of 2-methoxyethanol that had been previously dehydrated and manufactured by Kanto Chemical were weighed into a 20 g Pyrex reagent bottle containing a magnetic stirrer. The reagent bottle was then placed on a hot plate equipped with a magnetic stirrer and stirred at room temperature for 30 minutes to completely dissolve the strontium isopropoxide in the 2-methoxyethanol, followed by slow cooling to room temperature to obtain a 0.5 mol / kg concentration strontium isopropoxide in 2-methoxyethanol solution.

[0287] [1 mol / kg neodymium nitrate solution in 2-n-butoxyethanol] 4.2034g of neodymium nitrate n-hydrate (n=5) manufactured by Kojundo Chemical Laboratory and 5.7966g of pre-dehydrated 2-n-butoxyethanol manufactured by Kanto Chemical were weighed into a 20g Pyrex reagent bottle containing a magnetic stirrer. The bottle was then placed on a hot plate equipped with a magnetic stirrer and stirred at 140°C for 30 minutes to completely dissolve the neodymium nitrate n-hydrate (n=5) in the 2-n-butoxyethanol. The solution was then cooled slowly to room temperature to obtain a 1mol / kg neodymium nitrate 2-n-butoxyethanol solution. The hydration number n of the neodymium nitrate n-hydrate used was 5 based on the results of the mass loss in a combustion experiment (differential thermal analysis).

[0288] [1 mol / kg yttrium nitrate solution in ethyl alcohol] 3.8301 g of 3N yttrium nitrate hexahydrate (Kojundo Chemical Laboratory Co., Ltd.) and 6.1699 g of EL grade ethyl alcohol (Kanto Chemical Co., Ltd.) were weighed into a 20 g Pyrex reagent bottle containing a magnetic stirrer. The bottle was then placed on a hot plate equipped with a magnetic stirrer and stirred at 75°C for 30 minutes to completely dissolve the yttrium nitrate hexahydrate in the ethyl alcohol. The bottle was then gradually cooled to room temperature to obtain an ethyl alcohol solution of yttrium nitrate with a concentration of 1 mol / kg.

[0289] [1mol / kg calcium nitrate solution in 2-n-butoxyethanol] 2.3600 g of calcium nitrate tetrahydrate (3N, Kanto Chemical Co., Ltd.) and 7.6400 g of 2-n-butoxyethanol were weighed into a 20 g Pyrex reagent bottle containing a magnetic stirrer bar. The bottle was then placed on a magnetic stirrer with a hot plate function and stirred at 100°C for 30 minutes to completely dissolve calcium nitrate tetrahydrate in the 2-n-butoxyethanol. The bottle was then gradually cooled to room temperature to obtain a 1 mol / kg calcium nitrate solution in 2-n-butoxyethanol.

[0290] [1mol / kg concentration of zirconium tetra-n-butoxide in 2-n-butoxyethanol] 3.8368 g of zirconium tetra-n-butoxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 6.1632 g of 2-n-butoxyethanol that had been previously dehydrated and manufactured by Kanto Chemical Co., Ltd. were weighed into a 20 g Pyrex reagent bottle containing a magnetic stirrer bar. Next, the reagent bottle was placed on a magnetic stirrer, and the zirconium tetra-n-butoxide was completely dissolved in the 2-n-butoxyethanol while stirring at room temperature for 30 minutes, to obtain a 2-n-butoxyethanol solution of zirconium tetra-n-butoxide with a concentration of 1 mol / kg.

[0291] [1mol / kg concentration of niobium pentoxide in 2-n-butoxyethanol] 3.1821 g of niobium pentabutoxide (4N, manufactured by Kojundo Chemical Laboratory Co., Ltd.) and 6.8179 g of 2-n-butoxyethanol were weighed into a 20 g Pyrex reagent bottle containing a magnetic stir bar. Next, the reagent bottle was placed on a magnetic stirrer, and the niobium pentabutoxide was completely dissolved in the 2-n-butoxyethanol while stirring at room temperature for 30 minutes, to obtain a 2-n-butoxyethanol solution of niobium pentabutoxide with a concentration of 1 mol / kg.

[0292] [1 mol / kg solution of antimony tri-n-butoxide in 2-n-butoxyethanol] 3.4110 g of antimony tri-normal butoxide (5N, manufactured by Kojundo Chemical Laboratory Co., Ltd.) and 6.5890 g of 2-n-butoxyethanol were weighed into a 20 g Pyrex reagent bottle containing a magnetic stir bar. Next, the reagent bottle was placed on a magnetic stirrer, and the antimony tri-normal butoxide was completely dissolved in the 2-n-butoxyethanol while stirring at room temperature for 30 minutes, to obtain a 2-n-butoxyethanol solution of antimony tri-normal butoxide with a concentration of 1 mol / kg.

[0293] [1 mol / kg solution of tantalum pentaethoxide in 2-n-butoxyethanol] 5.4640 g of tantalum pentaethoxide (5N, manufactured by Kojundo Chemical Laboratory Co., Ltd.) and 4.5360 g of 2-n-butoxyethanol were weighed into a 20 g Pyrex reagent bottle containing a magnetic stir bar. Next, the reagent bottle was placed on a magnetic stirrer, and the tantalum pentaethoxide was completely dissolved in the 2-n-butoxyethanol while stirring at room temperature for 30 minutes, to obtain a 1 mol / kg concentration solution of tantalum pentaethoxide in 2-n-butoxyethanol.

[0294] [1 mol / kg solution of cerium nitrate in 2-n-butoxyethanol] 4.3422 g of 98% pure cerium nitrate hexahydrate (FUJIFILM Wako Pure Chemical Industries, Ltd., 98%) and 5.6578 g of 2-n-butoxyethanol were weighed into a 20 g Pyrex reagent bottle containing a magnetic stirrer bar. The bottle was then placed on a magnetic stirrer with a hot plate function and stirred at 140°C for 1 hour to completely dissolve the cerium nitrate in the 2-n-butoxyethanol. The bottle was then gradually cooled to room temperature to obtain a 1 mol / kg cerium nitrate in 2-n-butoxyethanol solution.

[0295] [1 mol / kg solution of tin tetraisopropoxide in 2-n-butoxyethanol] First, impurities contained in tin tetraisopropoxide (3N, manufactured by Kojundo Chemical Laboratory Co., Ltd.) are adsorbed onto neutral silica (e.g., Wakosil C-300 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)) to remove them. 3.5510 g of the adsorbed tin tetraisopropoxide and 6.4490 g of 2-n-butoxyethanol were weighed into a 20 g Pyrex reagent bottle containing a magnetic stirrer bar. Next, the reagent bottle was placed on a magnetic stirrer with a hot plate function, and the tin tetraisopropoxide was completely dissolved in the 2-n-butoxyethanol while stirring at 140°C for 30 minutes, and the mixture was gradually cooled to room temperature to obtain a 1 mol / kg concentration tin tetraisopropoxide in 2-n-butoxyethanol solution.

[0296] Next, the precursor solution was obtained by mixing the raw material solutions at a predetermined ratio. At this time, the mixing ratio of the raw material solutions was adjusted so that the content ratio of Li, Ga, La, Ca, Sr, Nd, Y, and Zr in the solid electrolyte produced using the precursor solution was 6.25:0.85 / 3:2.8:0.05:0.05:0.05:0.05:2.00 in molar ratio. The mass (g) of the 2-n-butoxyethanol solution of lithium nitrate with a concentration of 2 mol / kg is set in consideration of the mass of Li that volatilizes during the main firing at 1000°C. Specifically, before the main firing, the mass of the 2-n-butoxyethanol solution of lithium nitrate is set to 1.2 times the mass corresponding to Li6.25. The ratio of increase in the amount of lithium source considering the mass of Li that volatilizes during the main firing is not limited to 1.2 times, but depends on the firing temperature. For example, if the temperature in the heat treatment during the main firing is 800°C, the ratio of increase in the amount of lithium source may be 1.1 times. The amount of Li volatilized during the main firing is saturated when the firing time exceeds 1 hour. The amount of the raw material solution of elements other than the lithium source is set to be equal to the stoichiometric composition of the above composition formula.

[0297] (Preparation examples A2 to A7) A precursor solution was obtained in the same manner as in Preparation Example A1, except that the types of raw material solutions and the amounts used thereof were changed so that the content ratios of each metal element in the solid electrolyte produced using the precursor solution corresponded to those of Examples 9 to 14 shown in FIG. 21.

[0298] (Preparation examples A8 to A13) A precursor solution was obtained in the same manner as in Preparation Example A1, except that the types of raw material solutions and the amounts used thereof were changed so that the content ratios of each metal element in the solid electrolyte produced using the precursor solution would correspond to those of Comparative Examples 5 to 10 shown in FIG. 21.

[0299] [9-2] Production of solid electrolytes Example 8 A part of the precursor solution obtained in Preparation Example A1 was placed in a titanium petri dish and placed on a hot plate, heated at a set temperature of 160°C for 1 hour, and then heated at 180°C for 30 minutes to remove the solvent. The hot plate was then heated at a set temperature of 360°C for 30 minutes to decompose most of the organic components contained by combustion. After that, the hot plate was heated at a set temperature of 540°C for 1 hour to combust and decompose the remaining organic components. After that, the mixture was slowly cooled to room temperature on the hot plate to obtain a provisionally fired body.

[0300] The ash-like pyrolysis product (calcined body) obtained in this manner was a powder with an average particle size of 1 μm or less that contained a precursor oxide composed of a pyrochlore-type crystal phase and an oxo acid compound.

[0301] Next, the calcined powder was transferred to an agate mortar and thoroughly pulverized. The pulverized calcined powder was placed in a magnesium oxide crucible, covered with a magnesium oxide lid, and subjected to primary firing at 900°C for 12 hours in a Yamato Scientific electric muffle furnace FO100.

[0302] 0.200 g of the sintered powder thus obtained was weighed out and packed into a carbide die with an inner diameter of 10 mm as a molding die. The pulverized mixed powder was compression molded into pellets with a diameter of 10 mm under a load of 90 kN using a uniaxial pressure molding machine (NPa Systems, 100 kN Newton press).

[0303] Thereafter, the crucible was covered with an alumina lid, and the mixture was subjected to main firing in an electric furnace FO100 manufactured by Yamato Scientific Co., Ltd. The heating rate was 900°C / hour, the holding temperature was 1000°C, and the holding time at 1000°C was 10 hours.

[0304] After the electric furnace was cooled to room temperature, a disk-shaped solid electrolyte with a diameter of about 9.5 mm and a thickness of about 600 μm was taken out from the crucible. The cooling rate to 500° C. was 500° C. / hour, and the electrolyte was then allowed to cool naturally.

[0305] The mixing of raw materials, crushing of the fired powder, and molding were all carried out in a dry room with dew point control (-40°C).

[0306] The solid electrolyte thus obtained was confirmed by XRD measurement to be a single phase cubic garnet crystal without any impurity phase.

[0307] The composition of the obtained solid electrolyte was Li 6.25 Ga 0.85 / 3 La 2.8 Ca 0.05 Sr 0.05 Nd 0.05 Y 0.05 Zr 2 O 12 It was.

[0308] (Examples 9 to 14) Solid electrolytes were produced in the same manner as in Example 8, except that the precursor solutions prepared in Preparation Examples A2 to A7 were used, respectively.

[0309] (Comparative Examples 5 to 10) Solid electrolytes were produced in the same manner as in Example 8, except that the precursor solutions prepared in Preparation Examples A8 to A13 were used, respectively.

[0310] The compositions and crystal phases of the solid electrolytes of Examples 8 to 14 and Comparative Examples 5 to 10 are shown in FIG.

[0311]

[10] Evaluation of solid electrolytes obtained using liquid phase method The solid electrolytes of Examples 8 to 14 and Comparative Examples 5 to 10 obtained in [9-2] above were evaluated in the same manner as in [8] above ([8-1] to [8-3] above). These results are summarized in FIG.

[0312] As is clear from FIG. 22, the solid electrolytes of Examples 8 to 14 obtained by the liquid phase method also gave excellent results, similar to Examples 1 to 7 above. In contrast, the comparative examples did not provide satisfactory results.

[0313] In addition, solid electrolytes were produced in the same manner as in each of the above Examples, except that in the above composition formula (1), x was changed within the ranges of 0.10 or more and less than 1.00, y was changed within the ranges of 0.01 or more and 0.20 or less, z was changed within the ranges of 0.01 or more and 0.15 or less, and w was changed within the ranges of 0.01 or more and 0.20 or less, and these were evaluated in the same manner as above. In all cases, excellent results were obtained. [Explanation of symbols]

[0314] P100...solid electrolyte, P1...first mixture, P2...calcined body, P3'...crystalline solid electrolyte (first electrolyte), P3...first electrolyte part, P4'...second electrolyte, P4...second electrolyte part, P5...active material part, Q1...first compact, Q3...second compact, Q6...second mixture, Q7...third compact, 100...lithium ion battery, 10...composite, 30...negative electrode, 41...current collector, 42...current collector, 300...wearable device, 301...band, 302...sensor, 303...display unit, 304...processing unit, WR...wrist

Claims

1. A solid electrolyte represented by the following composition formula (1): (Li) ７－３ｘ Go ｘ＋ａ ) (No) ３－ｙ－ｚ－ｗ Nd ｙ Y ｚ M ｗ )Zr ２ Oh １２ ・・・(1) (In formula (1), M is at least one selected from the group consisting of Ca, Sr, and Rb, and satisfies 0.10≦x<1.00, 0.01≦y≦0.20, 0.01≦z≦0.15, and 0.01≦w≦0.

20. When M is Ca or Sr with a valence of 2+, a is 0.05 / 3 for one type, (0.05×2) / 3 for two types, and (0.05×3) / 3 for three types. When M is Rb with a valence of 1+, a is (0.05×2) / 3 for one type.)

2. 2. The solid electrolyte according to claim 1, wherein M is one selected from the group consisting of Ca, Sr and Rb.

3. 2. The solid electrolyte according to claim 1, wherein M is two or more elements selected from the group consisting of Ca, Sr and Rb.

Images