Composite, battery, and electronic apparatus

Abstract

To provide a composite applicable to production of a battery which is excellent in, e.g., adhesion between a solid electrolyte and an active material and has low grain-boundary resistance and high lithium-ion conductivity.SOLUTION: A composite includes an active material, a crystalline first electrolyte portion containing a lithium composite metal oxide represented by the formula (1), and a second electrolyte portion containing a lithium composite metal oxide represented by the formula (2) and configured to cover at least a part of a surface of the active material. At least a part of the first electrolyte portion is bonded to the active material through the second electrolyte portion. Here, the formula (1) is defined by (Li7-3x+yGax)(La3-yCay)Zr2O12, where in the formula (1), the relations 0.10≤x≤1.00 and 0.00<y≤0.30 are satisfied; and the formula (2) is defined by Li7-zLa3(Zr2-zMz)O12, where in the formula (2), the element M is two or more elements selected from the group consisting of Nb, Ta and Sb, and the relation 0.00<z<2.00 is satisfied.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a composite, a battery, and an electronic device. [Background technology]

[0002] Lithium ion batteries (including primary and secondary batteries) are used as power sources for many electronic 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] As the solid electrolyte used in such all-solid-state lithium-ion batteries, oxide-based solid electrolytes that have high lithium ion conductivity, excellent insulation properties, and high chemical stability are widely known. Among such oxides, lanthanum zirconate-based materials have particularly high lithium ion conductivity and are expected to be applied to 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, when using such a solid electrolyte, it is impossible to sufficiently improve the adhesion between the solid electrolyte and the active material and the adhesion between the solid electrolyte particles. As a result, the grain boundary resistance increases, and the lithium ion conductivity tends to decrease. Consequently, there is a problem that the discharge capacity tends to decrease, and particularly, the maintenance rate of the discharge capacity when charge and discharge are repeated tends to be low.

Means for Solving the Problems

[0007] The composite according to the application example of the present invention includes an active material and a crystalline first electrolyte part containing a lithium composite metal oxide represented by the following compositional formula (1), a second electrolyte part containing a lithium composite metal oxide represented by the following compositional formula (2) and covering at least a part of the surface of the active material, and is provided with at least a part of the first electrolyte part is joined to the active material via the second electrolyte part. (Li 7-3x+y Ga x )(La 3-y Ca y )Zr2O 12 ···(1) (However, in formula (1), the relationship of 0.10 ≦ x ≦ 1.00, 0.00 < y ≦ 0.30 is satisfied.) Li 7-z La3(Zr 2-z M z )O 12 ···(2) (However, in formula (2), the element M is two or more elements selected from the group consisting of Nb, Ta, and Sb, and satisfies the relationship of 0.00 < z < 2.00.)

[0008] In addition, the battery according to the application example of the present invention includes the composite according to the application example of the present invention and an electrode provided on one surface side of the composite, a current collector provided on the other surface side of the composite, and is provided with In addition, the electronic device according to the application example of the present invention includes the battery according to the application example of the present invention.

Brief Description of the Drawings

[0009] [Figure 1] FIG. 1 is an enlarged cross-sectional view showing a schematic example of the composite of the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing a structure of a lithium ion secondary battery. [Diagram 3] FIG. 3 is a perspective view showing a configuration of a wearable device as an electronic device. [Figure 4] FIG. 4 is a table showing the conditions for the composites of Examples A1 to A16 and the heating temperatures in the firing treatment. [Diagram 5] FIG. 5 is a table showing the conditions for the composites of Examples A17 to A19 and Comparative Examples A1 to A12, and the heating temperatures in the firing treatment. [Figure 6] FIG. 6 is a table summarizing the evaluation results for the composites of Examples A1 to A16. [Figure 7] FIG. 7 is a table summarizing the evaluation results for the composites of Examples A17 to A19 and Comparative Examples A1 to A12. [Figure 8] FIG. 8 is a table showing the evaluation results for the batteries of Examples B1 to B16. [Figure 9] FIG. 9 is a table showing the evaluation results for the batteries of Examples B17 to B19 and Comparative Examples B1 to B12. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Preferred embodiments of the present invention will now be described in detail. [1] Complex First, the complex of the present invention will be described. FIG. 1 is an enlarged cross-sectional view showing a schematic example of the composite of the present invention.

[0011] As shown in FIG. 1, the composite P100 includes an active material P10, a crystalline first electrolyte part P11, and a second electrolyte part P12 that covers at least a part of the surface of the active material P10. At least a part of the first electrolyte part P11 is joined to the active material P10 via the second electrolyte part P12.

[0012] In other words, the composite P100 includes an active material P10, a crystalline first electrolyte part P11 containing a lithium composite metal oxide represented by the following compositional formula (1), and a second electrolyte part P12 that contains a lithium composite metal oxide represented by the following compositional formula (2) and covers at least a part of the surface of the active material P10. That is, the second electrolyte part P12 is interposed between the active material P10 and the first electrolyte part P11.

[0013] The first electrolyte part P11 contains a lithium composite metal oxide represented by the following compositional formula (1), and the second electrolyte part P12 contains a lithium composite metal oxide represented by the following compositional formula (2).

[0014] (Li 7-3x+y Ga x )(La 3-y Ca y )Zr2O 12 ···(1) (However, in formula (1), the relationship 0.10 ≦ x ≦ 1.00, 0.00 < y ≦ 0.30 is satisfied.)

[0015] Li 7-z La3(Zr 2-z M z )O 12 ···(2) (However, in formula (2), the element M is two or more elements selected from the group consisting of Nb, Ta, and Sb, and the relationship 0.00 < z < 2.00 is satisfied.)

[0016] The above-mentioned structure makes it possible to provide a composite having excellent adhesion between the solid electrolyte and the active material, and between the solid electrolytes themselves, thereby suppressing an increase in grain boundary resistance and a decrease in lithium ion conductivity. Furthermore, by using such a composite, it is possible to provide a battery in which the discharge capacity is not easily decreased, and in particular, the discharge capacity is suitably maintained even when the battery is repeatedly charged and discharged.

[0017] On the other hand, if the above conditions are not met, satisfactory results will not be obtained. For example, if the active material has a portion corresponding to the first electrolyte part but does not have a portion corresponding to the second electrolyte part, the adhesion between the active material and the portion corresponding to the first electrolyte part will be poor, the grain boundary resistance will be high, and the lithium ion conductivity will be poor. As a result, when applied to a battery, the discharge capacity is likely to decrease, and in particular, the retention rate of the discharge capacity when the battery is repeatedly charged and discharged is likely to decrease.

[0018] In addition, when the portion corresponding to the first electrolyte part is composed of another electrolyte instead of the lithium composite metal oxide represented by the composition formula (1), the adhesion between the active material and the portion corresponding to the first electrolyte part cannot be sufficiently excellent, the grain boundary resistance increases, and the lithium ion conductivity cannot be sufficiently excellent. As a result, when applied to a battery, the discharge capacity is likely to decrease, and in particular, the retention rate of the discharge capacity when charging and discharging is repeated is likely to decrease.

[0019] In particular, when the electrolyte constituting the portion corresponding to the first electrolyte portion has a composition in which x in the above composition formula (1) is less than the lower limit, the lithium ion conductivity, particularly the conductivity within the particle bulk, is significantly reduced.

[0020] Furthermore, when the electrolyte constituting the site corresponding to the first electrolyte portion has a composition in which x in the composition formula (1) exceeds the upper limit, Ga (gallium) cannot be accommodated in the crystal lattice of the electrolyte, and highly insulating gallium oxide is produced, resulting in a problem of a decrease in the total lithium ion conductivity.

[0021] Furthermore, when the electrolyte constituting the site corresponding to the first electrolyte portion has a composition in which y in the above composition formula (1) is 0, that is, when it does not contain Ca, the lithium ion conductivity decreases significantly.

[0022] Furthermore, when the electrolyte constituting the site corresponding to the first electrolyte portion has a composition in which y in the above composition formula (1) exceeds the above upper limit, Ca cannot be accommodated in the crystal lattice of the electrolyte, and calcium oxide with high insulating properties is produced, resulting in a problem of a decrease in the total lithium ion conductivity.

[0023] In addition, when the portion corresponding to the second electrolyte part is composed of another electrolyte instead of the lithium composite metal oxide represented by the composition formula (2), the adhesion between the active material and the portion corresponding to the first electrolyte part cannot be sufficiently excellent, the grain boundary resistance increases, and the lithium ion conductivity cannot be sufficiently excellent. As a result, when applied to a battery, the discharge capacity is likely to decrease, and in particular, the retention rate of the discharge capacity when charging and discharging is repeated is likely to decrease.

[0024] In particular, when the electrolyte constituting the portion corresponding to the second electrolyte portion has a composition in which z in the above composition formula (2) is 0.00, i.e., a composition that does not contain the element M, it is difficult to sufficiently increase the initial total ion conductivity itself even if the decrease in total ion conductivity when placed under air can be suppressed.

[0025] Furthermore, when the electrolyte constituting the portion corresponding to the second electrolyte portion has a composition in which z in the above composition formula (2) is 2.00 or more, even if the decrease in total ionic conductivity when placed under air can be suppressed, it becomes difficult to sufficiently increase the initial total ionic conductivity itself.

[0026] In addition, when the portion corresponding to the second electrolyte part is composed of another electrolyte instead of the lithium composite metal oxide represented by the composition formula (2) above, even if the decrease in the total ion conductivity when placed in the air can be suppressed, it is difficult to sufficiently increase the initial total ion conductivity itself. In such a case, the electrolyte constituting the portion corresponding to the second electrolyte part may be, for example, an electrolyte in which the element M in the composition formula (2) above is only one selected from the group consisting of Nb, Ta, and Sb.

[0027] [1-1]Active material The active material P10 constituting the composite P100 may be either a negative electrode active material or a positive electrode active material.

[0028] Examples of negative electrode active materials include Nb2O5, V2O5, TiO2, In2O3, ZnO, SnO2, NiO, ITO, AZO, GZO, ATO, FTO, and Li4Ti5O. 12 and lithium double oxides such as Li2Ti3O7. 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 and substances in which lithium ions are inserted between layers of carbon materials such as LiC6.

[0029] 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. Examples of such composite oxides include composite metal compounds containing lithium (Li) and at least one element selected from vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu). Examples of such lithium composite oxides include LiCoO2, LiNiO2, LiMn2O4, Li2Mn2O3, NMC(Li p (Ni x Mn 1-x-y Co y )O2), NCA(Li(Ni x Co y Al 1-x-y )O2), LiCr 0.5 Mn 0.5 Examples of the positive electrode active material include O2, LiFePO4, Li2FeP2O7, LiMnPO4, LiFeBO3, Li3V2(PO4)3, Li2CuO2, Li2FeSiO4, and Li2MnSiO4. In addition, the positive electrode active material may be a solid solution in which some atoms in the crystal of the lithium double oxide as described above are replaced with other transition metals, typical metals, alkali metals, alkaline rare earths, lanthanoids, chalcogenides, halogens, and the like. In addition, examples of the positive electrode active material include fluorides such as LiFeF3, LiBH4, and Li4BN3H. 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.

[0030] The active material P10 is preferably a positive electrode active material, more preferably a positive electrode active material containing Li, and even more preferably a lithium double oxide.

[0031] This can improve the adhesion between the active material P10 and the second electrolyte portion P12, and can improve the charge / discharge performance under high load of a battery including the composite P100.

[0032] Also, for example, a coating layer may be formed on the surface of the active material P10 for the purpose of reducing the interface resistance with the solid electrolyte, particularly the second electrolyte portion P12, improving electronic conductivity, etc. For example, by forming a thin film of LiNbO3, Al2O3, ZrO2, Ta2O5, etc. on the surface of the positive electrode active material made of LiCoO2, the interface resistance of lithium ion conduction can be further reduced. The thickness of the coating layer is not particularly limited, but is preferably 3 nm or more and 1 μm or less.

[0033] The active material P10 may be, for example, a porous body having internal voids, and may be of any shape, for example, spherical, scaly, amorphous, columnar, plate-like, sheet-like, chip-like, pellet-like, block-like, etc., but in the configuration shown in the figure, it is granular.

[0034] When the active material P10 is granular, the average particle size of the active material P10 is not particularly limited, but is preferably 0.1 μm or more and 150 μm or less, more preferably 0.3 μm or more and 10 μm or less, and even more preferably 0.5 μm or more and 5 μm or less. This makes it easier to achieve both an actual capacity density close to the theoretical capacity of the active material P10 and a high charge / discharge rate.

[0035] 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 in an ultrasonic disperser for 3 minutes, and measuring the dispersion using a Coulter Counter particle size distribution measuring instrument (TA-II model manufactured by COULTER ELECTRONICS INS) with an aperture of 50 μm.

[0036] The particle size distribution of the active material P10 is not particularly limited, and may be, for example, a particle size distribution having one peak with a half-width of 0.1 μm to 19 μm. The particle size distribution of the active material may have two or more peaks.

[0037] The bulk density of the active material P10 is preferably 50% or more and 90% or less, and more preferably 50% or more and 70% or less.

[0038] This increases the surface area within the pores of the active material P10, making it easier to increase the contact area between the active material P10 and the electrolyte, in particular the second electrolyte portion P12, and facilitating a further increase in capacity in a battery including the composite P100.

[0039] If the bulk density is β (%), the apparent volume including the pores of the active material P10 is v, the mass of the active material P10 is w, and the density of the particles of the active material P10 is ρ, then the following formula (a) is established, from which the bulk density can be calculated. β = {w / (v ρ)} × 100 (a)

[0040] The resistivity of the active material P10 is preferably 700 Ω·cm or less. This allows a better C-rate (charge / discharge rate) to be obtained in the battery comprising the composite P100.

[0041] The resistivity can be determined, for example, by attaching copper foil as an electrode to the surface of the active material P10 and performing a direct current polarization measurement.

[0042] The proportion of the active material P10 in the composite P100 is preferably 25% by mass or more and 75% by mass or less, more preferably 30% by mass or more and 70% by mass or less, and even more preferably 40% by mass or more and 60% by mass or less.

[0043] This makes it possible to obtain a battery that has an excellent balance between battery capacity and C rate (charge / discharge rate).

[0044] [1-2]First electrolyte part The composite P100 includes a crystalline first electrolyte portion P11 containing the lithium composite metal oxide represented by the above composition formula (1). In the following description, the lithium composite metal oxide represented by the above composition formula (1) is also referred to as the "first solid electrolyte."

[0045] In the above compositional formula (1), x only needs to satisfy the relationship of 0.10 ≦ x ≦ 1.00, but preferably satisfies the relationship of 0.20 ≦ x ≦ 1.00, more preferably satisfies the relationship of 0.20 ≦ x ≦ 0.90, and even more preferably satisfies the relationship of 0.20 ≦ x ≦ 0.80.

[0046] Thereby, the above-described effects can be more significantly exhibited. In addition, the affinity and adhesion between the first electrolyte part P11 and the second electrolyte part P12 can be made more excellent.

[0047] In the above compositional formula (1), y only needs to satisfy the relationship of 0.00 < y ≦ 0.30, but preferably satisfies the relationship of 0.01 ≦ y ≦ 0.27, more preferably satisfies the relationship of 0.02 ≦ y ≦ 0.24, and even more preferably satisfies the relationship of 0.03 ≦ y ≦ 0.20.

[0048] Thereby, the above-described effects can be more significantly exhibited. In addition, the affinity and adhesion between the first electrolyte part P11 and the second electrolyte part P12 can be made more excellent.

[0049] In addition, the first solid electrolyte constituting the first electrolyte part P11 may contain, in trace amounts, other elements in addition to the elements constituting the above compositional formula (1), that is, elements other than Li, Ga, La, Ca, Zr, and O. The other elements may be one kind or two or more kinds.

[0050] The content of the other elements contained in the first solid electrolyte is preferably 100 ppm or less, and more preferably 50 ppm or less.

[0051] When two or more kinds of elements are included as the other elements, the sum of the contents of these elements is adopted as the content of the other elements.

[0052] The first electrolyte part P11 only needs to contain the first solid electrolyte, and may further contain components other than the first solid electrolyte.

[0053] However, the content rate of components other than the first solid electrolyte in the first electrolyte part P11 is preferably 5.0 mass% or less, more preferably 3.0 mass% or less, and still more preferably 1.0 mass% or less.

[0054] The proportion of the first electrolyte part P11 in the composite P100 is preferably 25 mass% or more and 75 mass% or less, more preferably 30 mass% or more and 70 mass% or less, and still more preferably 40 mass% or more and 60 mass% or less.

[0055] Thereby, a battery with an especially excellent balance between battery capacity and C-rate (charge and discharge rate) can be obtained.

[0056] [1-3] Second electrolyte part The composite P100 includes a second electrolyte part P12 containing a lithium composite metal oxide represented by the above compositional formula (2). In the following description, the lithium composite metal oxide represented by the above compositional formula (2) is also referred to as the "second solid electrolyte". In FIG. 1, for convenience, it is illustrated as if the entire surface of the active material P10 is covered with the second electrolyte part P12, but at least a part of the surface of the active material P10 may be covered.

[0057] In the above compositional formula (2), z only needs to satisfy the relationship of 0.00 < z < 2.00, but preferably satisfies the relationship of 0.20 ≤ z ≤ 1.80, more preferably satisfies the relationship of 0.40 ≤ z ≤ 1.50, and still more preferably satisfies the relationship of 0.50 ≤ z ≤ 1.30.

[0058] Thereby, the above-described effects are more significantly exhibited. In addition, the affinity and adhesion of the second electrolyte part P12 to the active material P10 and the first electrolyte part P11 can be made more excellent.

[0059] The lithium composite metal oxide represented by the above composition formula (2) that constitutes the second electrolyte part P12 contains, as the element M, two or more elements selected from the group consisting of Nb, Ta, and Sb. When the element M that constitutes the lithium composite metal oxide contains at least Nb, when the lithium composite metal oxide is represented by the following composition formula (2'), the value of z' is preferably 0.01 or more and 0.40 or less, and more preferably 0.05 or more and 0.38 or less.

[0060] Li 7-z La3(Zr 2-z Nb z’ M’ z’’ )O 12 ···(2’) (However, in formula (2'), the element M' is one or more elements selected from the group consisting of Ta and Sb, and satisfies the relationships of 0.00 < z', 0.00 < z'', and 0.00 < z' + z'' < 2.00.)

[0061] Thereby, the crystallinity of the second electrolyte part is reduced, a smooth interface is formed, and the lithium ion conductivity is further improved.

[0062] In addition, the second solid electrolyte that constitutes the second electrolyte part P12 may contain, in trace amounts, other elements, that is, elements other than Li, La, Zr, Nb, Ta, Sb, and O, in addition to the elements that constitute the above composition formula (2). The other elements may be one kind or two or more kinds.

[0063] The content of the other elements contained in the second solid electrolyte is preferably 100 ppm or less, and more preferably 50 ppm or less.

[0064] When two or more elements are included as the other elements, the sum of the contents of these elements is adopted as the content of the other elements.

[0065] The second electrolyte part P12 only needs to contain the second solid electrolyte, and may further contain components other than the second solid electrolyte.

[0066] However, the content of components other than the second solid electrolyte in the second electrolyte portion P12 is preferably 5.0 mass % or less, more preferably 3.0 mass % or less, and even more preferably 1.0 mass % or less.

[0067] The proportion of the second electrolyte portion P12 in the composite P100 is preferably 0.06 mass % or more and 19.0 mass % or less, more preferably 0.09 mass % or more and 9.3 mass % or less, and even more preferably 0.12 mass % or more and 4.8 mass % or less. This makes it possible to obtain a battery with a superior C-rate (charge / discharge rate).

[0068] When the second electrolyte part P12 is formed in the form of a film on the surface of the active material P10, the average thickness of the second electrolyte part P12 is preferably 0.002 μm or more and 0.300 μm or less, more preferably 0.003 μm or more and 0.150 μm or less, and even more preferably 0.004 μm or more and 0.080 μm or less. This makes it possible to obtain a battery with a superior C-rate (charge / discharge rate).

[0069] In this specification, the average thickness of the second electrolyte part P12 refers to the thickness of the second electrolyte part P12 calculated from the mass of the active material P10 and the second electrolyte part P12 contained in the entire complex P100, assuming that the second electrolyte part P12 is provided with a uniform thickness on the entire outer surface of the active material P10. In particular, when the active material P10 is granular, the average thickness of the second electrolyte part P12 refers to the thickness of the second electrolyte part P12 calculated from the specific gravity, assuming that each active material P10 is a true sphere having a diameter equal to the average particle size, and assuming that the second electrolyte part P12 with a uniform thickness is formed on the entire outer surface of each active material P10.

[0070] Furthermore, when the active material P10 is granular, when the average particle size of the active material P10 is D [μm] and the average thickness of the second electrolyte portion P12 is T [μm], it is preferable that the relationship satisfies 0.0005≦T / D≦0.2500, it is more preferable that the relationship satisfies 0.0005≦T / D≦0.0700, and it is even more preferable that the relationship satisfies 0.0010≦T / D≦0.0200. This makes it possible to obtain a battery with a superior C-rate (charge / discharge rate).

[0071] The second electrolyte part P12 may cover at least a part of the surface of the active material P10, and the coverage of the second electrolyte part P12 to the outer surface of the active material P10, i.e., the ratio of the area of ​​the part covered by the second electrolyte part P12 to the total area of ​​the outer surface of the active material P10, is not particularly limited, but is preferably 30% or more, more preferably 40% or more, and even more preferably 50% or more. The upper limit of the coverage may be 100% or less. This makes the above-mentioned effects more pronounced.

[0072] [1-4]Third electrolyte section The composite of the present invention may have the above-mentioned configuration, i.e., the active material, the first electrolyte part, and the second electrolyte part, but in the configuration shown in the figure, in addition to the active material P10, the first electrolyte part P11, and the second electrolyte part P12, it further includes an amorphous third electrolyte part P13 containing Li that is in contact with the first electrolyte part P11. In particular, the third electrolyte part P13 is provided in the space inside the composite P100.

[0073] This allows the proportion of voids inside the composite P100 to be reduced, and the aforementioned effects of the present invention are more pronounced.

[0074] In the following description, the amorphous solid electrolyte constituting the third electrolyte portion P13 is also referred to as the "third solid electrolyte."

[0075] The third electrolyte portion P13 may be any electrolyte that contains an amorphous electrolyte containing Li, i.e., a third solid electrolyte. Examples of the third solid electrolyte include Li3BO3, Li3BO3-Li4SiO4, Li3BO3-Li3PO4, Li3BO3-Li2SO4, Li2CO3-Li3BO3, Li2O-TiO2, La2O3-Li2O-TiO2, LiNbO3, LiSO4, Li4SiO4, Li3PO4-Li4SiO4, Li4GeO4-Li3VO4, Li4SiO4-Li3VO4, Li4GeO4-Zn2GeO2, Li4SiO4-LiMoO4, Li4SiO4-Li4ZrO4, SiO2-P2O5-Li2O, SiO 2-P2O5-LiCl, Li2O-LiCl-B2O3, LiI, LiI-CaI2, LiI-CaO, LiAlCl4, LiAlF4, LiF-Al2O3, LiBr-Al2O3, LiI-Al2O3, Li 2.88 PO 3.73 N 0.14 , Li3NI2, Li3N-LiI-LiOH, Li3N-LiCl, Li6NBr3, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-P2S5, etc., and one or more selected from these can be used in combination.

[0076] In particular, the third electrolyte portion P13 preferably contains Li, B, and O. This can increase the lithium ion conductivity of the composite P100. In addition, such a third solid electrolyte generally has a low melting point, and a melt of the third solid electrolyte can be suitably filled into the voids inside the compact having the active material P10, the first electrolyte portion P11, and the second electrolyte portion P12, for example, by a method described later.

[0077] The third electrolyte portion P13 is in contact with the first electrolyte portion P11 and may contain a component other than the third solid electrolyte, provided that it contains a third solid electrolyte.

[0078] However, the content of components other than the third solid electrolyte in the third electrolyte portion P13 is preferably 5.0 mass % or less, more preferably 3.0 mass % or less, and even more preferably 1.0 mass % or less.

[0079] The proportion of the third electrolyte portion P13 in the composite P100 is preferably 1% by mass to 10% by mass, more preferably 1% by mass to 8% by mass, and even more preferably 1% by mass to 6% by mass.

[0080] This makes it possible to obtain a battery that has an excellent balance between battery capacity and C rate (charge / discharge rate).

[0081] [1-5] Other configurations The composite P100 may have components other than the above-mentioned active material P10, first electrolyte part P11, second electrolyte part P12, and third electrolyte part P13. Hereinafter, in this section, such components are also referred to as "other components."

[0082] Other configurations include, for example, a fourth electrolyte portion including a crystalline solid electrolyte represented by a composition formula other than the above composition formula (1) and the above composition formula (2).

[0083] However, the proportion of other components in the complex P100 is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and even more preferably 1.0% by mass or less.

[0084] [1-6] Other conditions The size and shape of the complex P100 are not particularly limited. In addition, in the illustrated configuration, the boundary between the active material P10 and the second electrolyte part P12, the boundary between the second electrolyte part P12 and the first electrolyte part P11, and the boundary between the first electrolyte part P11 and the third electrolyte part P13 are all clear, but these boundaries do not necessarily have to be clear, and part of the components of one of the adjacent parts, for example the active material P10 and the second electrolyte part P12, may migrate to the other.

[0085] In addition, in the illustrated configuration, the third electrolyte part P13 is in contact only with the first electrolyte part P11, but it may be in contact with the first electrolyte part P11 as well as with a portion other than the first electrolyte part P11, such as the active material P10 or the second electrolyte part P12.

[0086] In addition, in the illustrated configuration, the second electrolyte part P12 is in contact only with the active material P10 and the first electrolyte part P11, but it may be in contact with other parts, such as the third electrolyte part P13, together with the active material P10 and the first electrolyte part P11.

[0087] In addition, in the illustrated configuration, the first electrolyte part P11 is in contact only with the second electrolyte part P12 and the third electrolyte part P13, but it may be in contact with other parts, such as the active material P10, together with the second electrolyte part P12 and the third electrolyte part P13.

[0088] [2] Manufacturing method of the composite Next, a method for producing the composite of the present invention will be described. The composite of the present invention can be suitably produced, for example, by using a method including a second precursor contacting step of contacting an active material P10 with a solution containing a precursor of a second solid electrolyte, a first precursor contacting step of contacting an active material P10 that has been subjected to the second precursor contacting step with a solution containing a precursor of a first solid electrolyte, and a third electrolyte part formation step of contacting the active material P10 that has been subjected to the second precursor contacting step and the first precursor contacting step with a third solid electrolyte to form a third electrolyte part P13.

[0089] [2-1] Second precursor contact step In the second precursor contacting step, a solution containing a precursor of the second solid electrolyte is brought into contact with the active material P10.

[0090] The method for contacting the solution containing the precursor of the second solid electrolyte with the active material P10 is not particularly limited, and examples thereof include a method of adding the active material P10 to a solution containing the precursor of the second solid electrolyte, a method of applying a solution containing the precursor of the second solid electrolyte to the active material P10, and the like.

[0091] The active material P10 may be added to the solution containing the precursor of the second solid electrolyte by, for example, a dipping method.

[0092] Examples of the method for applying the solution containing the precursor of the second solid electrolyte to the active material P10 include a dropping method, a spraying method, a coating method, and a spin coating method.

[0093] As the solution containing a precursor of the second solid electrolyte, for example, a solution in which a lithium compound, a lanthanum compound, a zirconium compound, and a metal compound containing the element M are dissolved can be used.

[0094] Such a solution can be prepared, for example, by mixing a lithium raw material solution in which a lithium compound is dissolved, a lanthanum raw material solution in which a lanthanum compound is dissolved, a zirconium raw material solution in which a zirconium compound is dissolved, and a metal raw material solution in which a metal compound containing element M is dissolved. In this case, the order in which the raw material solutions are mixed is not particularly limited.

[0095] As described above, when raw material solutions are used, the solvents and dispersion media constituting these raw material solutions may have a common composition or may have different compositions.

[0096] In preparing the solution containing the precursor of the second solid electrolyte, it is preferable to use a lithium compound such that the lithium content in the solution is equal to or more than 1.2 times the stoichiometric composition of the composition formula (2) above.

[0097] In addition, in preparing the solution containing the precursor of the second solid electrolyte, it is preferable to use a lanthanum compound such that the content of lanthanum in the solution is equal to the stoichiometric composition of the composition formula (2) above.

[0098] In addition, in preparing the solution containing the precursor of the second solid electrolyte, it is preferable to use a zirconium compound such that the content of zirconium in the solution is equal to the stoichiometric composition of the composition formula (2) above.

[0099] In addition, in preparing the solution containing the precursor of the second solid electrolyte, it is preferable to use a metal compound containing element M such that the content of element M in the solution is equal to the stoichiometric composition of composition formula (2).

[0100] Examples of the lithium compound include lithium metal salts and lithium alkoxides, and one or more of these can be used in combination. Examples of the lithium metal salt include lithium chloride, lithium nitrate, lithium sulfate, lithium acetate, lithium hydroxide, lithium carbonate, and (2,4-pentanedionato)lithium. Examples of the lithium alkoxide include lithium methoxide, lithium ethoxide, lithium normal propoxide, lithium isopropoxide, lithium normal butoxide, lithium isobutoxide, lithium secondary butoxide, lithium tertiary 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 lithium source.

[0101] In addition, examples of the lanthanum compound, which is a metal compound serving as a lanthanum source, include lanthanum metal salts and lanthanum alkoxides, and one or more of these can be used in combination. Examples of the lanthanum metal salts include lanthanum chloride, lanthanum nitrate, lanthanum sulfate, lanthanum acetate, and lanthanum tris(2,4-pentanedionato). Examples of the lanthanum alkoxides include lanthanum trimethoxide, lanthanum triethoxide, lanthanum trinormal propoxide, lanthanum triisopropoxide, lanthanum trinormal butoxide, lanthanum triisobutoxide, lanthanum trisecondary butoxide, lanthanum tritertiary butoxide, and lanthanum tris(dipivaloylmethanato). Among these, the lanthanum compound is preferably at least one of lanthanum nitrate and lanthanum tris(2,4-pentanedionato). A hydrate may be used as the lanthanum source.

[0102] In addition, examples of the zirconium compound, which is a metal compound as a zirconium source, include, for example, 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 tetra-normal propoxide, zirconium tetraisopropoxide, zirconium tetra-normal butoxide, zirconium tetraisobutoxide, zirconium tetra-secondary butoxide, zirconium tetra-tertiary butoxide, and tetrakis(dipivaloylmethanato)zirconium. Among these, zirconium compounds are preferably zirconium tetra-normal butoxide. Hydrates may be used as the zirconium source.

[0103] In addition, the tantalum compound, which is a metal compound as a tantalum source of element M, may be, for example, a tantalum metal salt, a tantalum alkoxide, etc., and one or more of these may be used in combination. Examples of the tantalum metal salt include tantalum chloride and tantalum bromide. Examples of the tantalum alkoxide include tantalum pentamethoxide, tantalum pentaethoxide, tantalum pentaisopropoxide, tantalum pentanormal propoxide, tantalum pentaisobutoxide, tantalum pentanormal butoxide, tantalum pentasecondary butoxide, and tantalum pentatertiary butoxide. Among them, the tantalum compound is preferably one or more selected from the group consisting of tantalum pentaethoxide, tantalum pentanormal propoxide, and tantalum pentanormal butoxide. Hydrates may be used as the tantalum source.

[0104] In addition, antimony compounds, which are metal compounds serving as the antimony source of element M, include, for example, antimony metal salts and antimony alkoxides, and one or more of these can be used in combination. Examples of antimony metal salts include, for example, antimony bromide, antimony chloride, and antimony fluoride. Examples of antimony alkoxides include, for example, antimony trimethoxide, antimony triethoxide, antimony triisopropoxide, antimony trinormal propoxide, antimony triisobutoxide, and antimony trinormal butoxide. Among these, the antimony compound is preferably at least one of antimony triisobutoxide and antimony trinormal butoxide. Hydrates may be used as the antimony source.

[0105] In addition, examples of the niobium compound, which is a metal compound serving as a niobium source of element M, include, for example, niobium metal salt, niobium alkoxide, niobium acetylacetone, etc., and one or more of these can be used in combination. Examples of the niobium metal salt include, for example, niobium chloride, niobium oxychloride, niobium oxalate, etc. In addition, examples of the niobium alkoxide include, for example, niobium pentaethoxide, niobium pentanylpropoxide, niobium pentanylbutoxide, niobium pentaisopropoxide, niobium pentasecondarybutoxide, etc. Among these, niobium pentanylbutoxide is preferred as the niobium compound. Hydrates may be used as the niobium source.

[0106] Moreover, the solution containing the precursor of the second solid electrolyte preferably contains an oxoanion. This allows the second solid electrolyte to be suitably formed in the subsequent heat treatment, particularly in a heat treatment under relatively mild conditions. Furthermore, the second electrolyte part P12 made of the second solid electrolyte thus formed has excellent adhesion to the active material P10 and the first electrolyte part P11 made of the first solid electrolyte. As a result, the reliability of the composite P100 finally obtained can be improved.

[0107] In this step, when the solution containing the precursor of the second solid electrolyte is prepared as one containing an oxoanion, it is preferable to use a metal salt containing an oxoanion as the various metal compounds serving as raw materials for forming the second solid electrolyte described above. However, an oxoacid compound containing an oxoanion but not a metal element may be further used as a component different from the various metal compounds in preparing the solution containing the precursor of the second solid electrolyte.

[0108] Examples of oxoanions include halogen oxoacid ions, 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, sulfinate ions, etc. 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, periodate ions, etc.

[0109] The oxo acid compound may be added, for example, after this step, during the heat treatment described below or during the heat treatment.

[0110] In the second precursor contacting step, the active material P10 brought into contact with the solution containing the precursor of the second solid electrolyte may, for example, satisfy the same conditions as the active material P10 constituting the composite P100, or may satisfy different conditions. More specifically, for example, the active material P10 brought into contact with the solution containing the precursor of the second solid electrolyte in the second precursor contacting step may have different conditions, such as shape and size, from the active material P10 constituting the composite P100.

[0111] The solvent and the dispersion medium are not particularly limited, and for example, water and various organic solvents can be used. Examples of the organic solvent include alcohols, glycols, ketones, esters, ethers, organic acids, aromatics, amides, and the like, and a mixed solvent of one or more selected from these can be used. Examples of the alcohols include methyl alcohol, ethyl alcohol, normal propyl alcohol, isopropyl alcohol, normal butyl alcohol, 2-propen-1-ol, and 2-normal butoxyethanol. Examples of the glycols include ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, pentanediol, hexanediol, heptanediol, and dipropylene glycol. Examples of the ketones include dimethyl ketone, methyl ethyl ketone, methyl propyl ketone, and methyl isobutyl ketone. Examples of the esters include methyl formate, ethyl formate, methyl acetate, and methyl acetoacetate. Examples of ethers include 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 and the dispersion medium are preferably at least one of 2-normal butoxyethanol and ethyl alcohol.

[0112] [2-2] First heat treatment process In this embodiment, prior to the first precursor contacting step described below, the active material P10 that has been subjected to the second precursor contacting step described above, ie, the active material P10 to which the precursor of the second solid electrolyte is adhered, is heated.

[0113] Thereby, for example, the solvent and dispersion medium contained in the solution containing the precursor of the second solid electrolyte can be preferably removed, and at least a part of the precursor of the second solid electrolyte can be converted into a metal oxide of the second solid electrolyte. In particular, when the solution containing the precursor of the second solid electrolyte contains an oxoanion, an oxide different from the second solid electrolyte can be preferably formed in this process. Hereinafter, the oxide is also referred to as a "second precursor oxide". As a result, for example, the precursor of the second solid electrolyte or the second solid electrolyte attached to the active material P10 is effectively prevented from being unintentionally peeled off in a later process. In addition, the adhesion of the second electrolyte part P12 made of the second solid electrolyte to the active material P10 and the first electrolyte part P11 made of the first solid electrolyte in the composite P100 can be made more excellent. As a result, the reliability of the composite P100 finally obtained can be made more excellent.

[0114] In the following description, the case where the solution containing the precursor of the second solid electrolyte contains oxoanions and a second precursor oxide is formed in this step will be mainly described.

[0115] The heating in this step is preferably carried out under conditions such that the content of liquid components contained in the solution containing the precursor of the second solid electrolyte becomes sufficiently low. More specifically, the content of liquid components contained in the solid composition obtained in this process, i.e., the content of the above-mentioned solvent and dispersion medium, is preferably 1.0 mass % or less, and more preferably 0.1 mass % or less.

[0116] The heat treatment in this step may be carried out under fixed conditions or under a combination of different conditions.

[0117] For example, a heat treatment A having the main purpose of removing the above-mentioned solvent and dispersion medium and a heat treatment B having the main purpose of reacting the precursors of the second solid electrolyte, i.e., the above-mentioned lithium compound, lanthanum compound, zirconium compound, and metal compound containing element M, may be combined.

[0118] In this case, for example, the heat treatment A can make the portion corresponding to the solution containing the precursor of the second solid electrolyte applied in the second precursor contacting step into one composed of a gelled composition, and the subsequent heat treatment B can make it into a state containing almost no liquid components as described above. In particular, when the solution containing the precursor of the second solid electrolyte contains oxoanions, the heat treatment B can efficiently form the second precursor oxide.

[0119] The conditions for heat treatment A vary depending on the boiling point and vapor pressure of the solvent and dispersion medium, but the heating temperature in heat treatment A 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.

[0120] The heating time in the heat treatment A 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.

[0121] Heat treatment A 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 nitrogen gas, helium gas, argon gas, or other inert gas atmosphere. Heat treatment A may also be performed under reduced pressure or vacuum, or under pressure.

[0122] During the heat treatment A, the atmosphere may be maintained at substantially the same conditions, or may be changed to different conditions.

[0123] The conditions for heat treatment B depend on factors such as the composition of the second precursor oxide to be formed, but the heating temperature in heat treatment B is preferably 400°C or higher and 600°C or lower, more preferably 430°C or higher and 600°C or lower, and even more preferably 450°C or higher and 600°C or lower.

[0124] The heating time in the heat treatment B is preferably from 5 minutes to 180 minutes, more preferably from 10 minutes to 120 minutes, and even more preferably from 15 minutes to 120 minutes.

[0125] Heat treatment B 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 nitrogen gas, helium gas, argon gas, or other inert gas atmosphere. Heat treatment B may be performed under reduced pressure, vacuum, or pressure. It is particularly preferable to perform heat treatment B in an oxidizing atmosphere.

[0126] Heat treatment A and heat treatment B may be carried out successively. For example, the temperature may be increased at a constant rate in heat treatment A without any time for maintaining the temperature within a predetermined range.

[0127] When the solid composition obtained in this step contains a second precursor oxide, the second precursor oxide preferably has a crystal structure different from that of the second solid electrolyte. In the present invention, the term "different" in relation to the crystal structure is a broad concept that includes not only crystal structures that are not the same type, but also crystal structures that are the same type but have at least one different lattice constant.

[0128] In particular, it is preferable that the second solid electrolyte is composed of a solid electrolyte having a cubic garnet-type crystal structure, while the crystal structure of the second precursor oxide is a tetragonal garnet-type crystal structure or a pyrochlore oxide structure.

[0129] As a result, even if the conditions of the heat treatment after this step are relaxed, for example, at a lower temperature or for a shorter time, it is possible to preferably form the second electrolyte part P12 made of a solid electrolyte that has excellent adhesion to the active material P10 and the first electrolyte part P11 and is particularly excellent in properties such as ion conductivity.

[0130] The crystal structure of the second precursor oxide may be a crystal structure other than the above-mentioned tetragonal garnet-type crystal structure or pyrochlore oxide structure, for example, a cubic crystal such as a perovskite structure, a rock salt structure, a diamond structure, a fluorite structure, or a spinel structure, an orthorhombic crystal such as a ramsdellite structure, or a trigonal crystal such as a corundum structure.

[0131] The crystal grain size of the second 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.

[0132] This allows the melting temperature of the second precursor oxide to be further lowered by the Gibbs-Thomson effect, which is a melting point drop caused by an increase in surface energy, and further relaxes the conditions for the heat treatment after this step. Also, the adhesion between the active material P10 and the second electrolyte part P12, and between the second electrolyte part P12 and the first electrolyte part P11 in the finally obtained composite P100 can be improved.

[0133] The second precursor oxide is preferably composed of a substantially single crystal structure.

[0134] As a result, in the heat treatment subsequent to this step, the crystal phase transition that occurs when forming a solid electrolyte having a cubic garnet-type crystal structure is substantially limited to one time, thereby suppressing the segregation of elements that accompanies the crystal phase transition and the generation of impurity crystals due to thermal decomposition, and further improving various properties of the second solid electrolyte.

[0135] In addition, when an object 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 to 1000°C, the object can be determined to be "substantially composed of a single crystal structure."

[0136] [2-3] First precursor contact step In the first precursor contacting step, a solution containing a precursor of the first solid electrolyte is brought into contact with the active material P10 that has been subjected to the second precursor contacting step.

[0137] The method for contacting the solution containing the precursor of the first solid electrolyte with the active material P10 that has undergone the second precursor contacting step is not particularly limited, and examples thereof include a method of adding the active material P10 that has undergone the second precursor contacting step to a solution containing the precursor of the first solid electrolyte, and a method of applying a solution containing the precursor of the first solid electrolyte to the active material P10 that has undergone the second precursor contacting step.

[0138] Examples of a method for adding the active material P10 that has been subjected to the second precursor contact step to a solution containing the precursor of the first solid electrolyte include an immersion method.

[0139] Examples of a method for applying the solution containing the precursor of the first solid electrolyte to the active material P10 that has been subjected to the second precursor contact step include a dropping method, a spraying method, a coating method, and a spin coating method.

[0140] As the solution containing the precursor of the first solid electrolyte, for example, a solution in which a lithium compound, a gallium compound, a lanthanum compound, a calcium compound, and a zirconium compound are dissolved can be used.

[0141] Such a solution can be prepared, for example, by mixing a lithium raw material solution in which a lithium compound is dissolved, a gallium raw material solution in which a gallium compound is dissolved, a lanthanum raw material solution in which a lanthanum compound is dissolved, a calcium raw material solution in which a calcium compound is dissolved, and a zirconium raw material solution in which a zirconium compound is dissolved. In this case, the order in which each raw material solution is mixed is not particularly limited.

[0142] As described above, when raw material solutions are used, the solvents and dispersion media constituting these raw material solutions may have a common composition or may have different compositions.

[0143] In preparing the solution containing the precursor of the first solid electrolyte, it is preferable to use a lithium compound such that the lithium content in the solution is 1.05 to 1.30 times the stoichiometric composition of the composition formula (1) above.

[0144] In addition, in preparing the solution containing the precursor of the first solid electrolyte, it is preferable to use a gallium compound such that the content of gallium in the solution is equal to the stoichiometric composition of the composition formula (1) above.

[0145] In addition, in preparing the solution containing the precursor of the first solid electrolyte, it is preferable to use a lanthanum compound such that the content of lanthanum in the solution is equal to the stoichiometric composition of the composition formula (1) above.

[0146] In addition, in preparing the solution containing the precursor of the first solid electrolyte, it is preferable to use a calcium compound such that the calcium content in the solution is equal to the stoichiometric composition of the composition formula (1) above.

[0147] In addition, in preparing the solution containing the precursor of the first solid electrolyte, it is preferable to use a zirconium compound such that the content of zirconium in the solution is equal to the stoichiometric composition of the composition formula (1) above.

[0148] As the lithium source, lanthanum source and zirconium source contained in the solution containing the precursor of the first solid electrolyte, for example, the lithium compounds, lanthanum compounds and zirconium compounds exemplified as the components contained in the solution containing the precursor of the second solid electrolyte in the above [2-1] can be used, and it is preferable that the conditions are the same as those described in the above [2-1].

[0149] In addition, the gallium compound, which is a metal compound as a gallium source, can be, for example, gallium metal salt, gallium alkoxide, etc., and one or more of these can be used in combination. The gallium metal salt can be, for example, gallium bromide, gallium chloride, gallium iodide, gallium nitrate, etc. The gallium alkoxide can be, for example, gallium trimethoxide, gallium triethoxide, gallium trinormal propoxide, gallium triisopropoxide, gallium trinormal butoxide, etc. Among them, gallium nitrate is preferable as the gallium compound. As the gallium source, a hydrate can be used.

[0150] In addition, examples of calcium compounds that are metal compounds serving as calcium sources include calcium metal salts and calcium alkoxides, and one or more of these can be used in combination. Examples of calcium metal salts include calcium bromide, calcium chloride, calcium fluoride, calcium iodide, calcium oxalate, calcium acetate, and calcium nitrate. Examples of calcium alkoxides include calcium dimethoxide, calcium diethoxide, calcium diisopropoxide, calcium di-normal propoxide, calcium diisobutoxide, calcium di-normal butoxide, and calcium di-secondary butoxide. Among these, calcium nitrate is preferred as the calcium compound. Hydrates may be used as the calcium source.

[0151] Moreover, the solution containing the precursor of the first solid electrolyte preferably contains an oxoanion.

[0152] This allows the first solid electrolyte to be suitably formed in the subsequent heat treatment, particularly in a heat treatment under relatively mild conditions. Furthermore, the first electrolyte portion P11 made of the first solid electrolyte thus formed has excellent adhesion to the second electrolyte portion P12 made of the second solid electrolyte. As a result, the reliability of the composite P100 finally obtained can be improved.

[0153] In this step, when the solution containing the precursor of the first solid electrolyte is prepared as one containing an oxoanion, it is preferable to use a metal salt containing an oxoanion as the various metal compounds serving as raw materials for forming the first solid electrolyte described above. However, an oxoacid compound containing an oxoanion but not a metal element may also be used as a component different from the various metal compounds in preparing the solution containing the precursor of the first solid electrolyte.

[0154] Examples of oxoanions include those exemplified in [2-1] above. The oxo acid compound may be added, for example, after this step, during the heat treatment described below or during the heat treatment.

[0155] The solvent and the dispersion medium constituting the solution containing the precursor of the first solid electrolyte are not particularly limited, and may be, for example, those exemplified in the above [2-1], etc. Among them, the solvent and the dispersion medium are preferably at least one of 2-n-butoxyethanol and ethyl alcohol.

[0156] [2-4] Second heat treatment process In this embodiment, prior to the third electrolyte part formation process described later, the active material P10 that has undergone the first precursor contact process described above, i.e., the active material P10 to which the second precursor oxide and the precursor of the first solid electrolyte are attached, is heated.

[0157] Thereby, for example, the solvent and dispersion medium contained in the solution containing the precursor of the first solid electrolyte can be preferably removed, and at least a part of the precursor of the first solid electrolyte can be converted into a metal oxide such as the first solid electrolyte. In particular, when the solution containing the precursor of the first solid electrolyte contains an oxoanion, an oxide different from the first solid electrolyte can be preferably formed in this process. Hereinafter, the oxide is also referred to as the "first precursor oxide". As a result, for example, the precursor of the first solid electrolyte or the first solid electrolyte attached to the second precursor oxide or the second solid electrolyte on the active material P10 is effectively prevented from being unintentionally peeled off in a later process. In addition, the adhesion of the first electrolyte part P11 composed of the first solid electrolyte to the second electrolyte part P12 and the third electrolyte part P13 in the composite P100 can be made more excellent. As a result, the reliability of the composite P100 finally obtained can be made more excellent.

[0158] In the following description, the case where the solution containing the precursor of the first solid electrolyte contains oxoanions and a first precursor oxide is formed in this step will be mainly described.

[0159] The heating in this step is preferably carried out under conditions such that the content of liquid components contained in the solution containing the precursor of the first solid electrolyte becomes sufficiently low. More specifically, the content of liquid components contained in the solid composition obtained in this process, i.e., the content of the above-mentioned solvent and dispersion medium, is preferably 1.0 mass % or less, and more preferably 0.1 mass % or less.

[0160] The heat treatment in this step may be carried out under fixed conditions or under a combination of different conditions.

[0161] For example, a heat treatment A having the main purpose of removing the above-mentioned solvent and dispersion medium and a heat treatment B having the main purpose of reacting the precursors of the first solid electrolyte, i.e., the above-mentioned lithium compound, gallium compound, lanthanum compound, calcium compound, and zirconium compound, may be combined.

[0162] In this case, for example, the heat treatment A can make the portion corresponding to the solution containing the precursor of the first solid electrolyte applied in the first precursor contacting step into one composed of a gelled composition, and the subsequent heat treatment B can make it into a state containing almost no liquid components as described above. In particular, when the solution containing the precursor of the first solid electrolyte contains oxoanions, the heat treatment B can efficiently form the first precursor oxide.

[0163] The conditions for heat treatment A vary depending on the boiling point and vapor pressure of the solvent and dispersion medium, but the heating temperature in heat treatment A 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.

[0164] The heating time in the heat treatment A 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.

[0165] Heat treatment A 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 nitrogen gas, helium gas, argon gas, or other inert gas atmosphere. Heat treatment A may also be performed under reduced pressure or vacuum, or under pressure.

[0166] During the heat treatment A, the atmosphere may be maintained at substantially the same conditions, or may be changed to different conditions.

[0167] The conditions for heat treatment B depend on factors such as the composition of the first precursor oxide to be formed, but the heating temperature in heat treatment B is preferably 400°C or higher and 600°C or lower, more preferably 430°C or higher and 600°C or lower, and even more preferably 450°C or higher and 600°C or lower.

[0168] The heating time in the heat treatment B is preferably from 5 minutes to 180 minutes, more preferably from 10 minutes to 120 minutes, and even more preferably from 15 minutes to 120 minutes.

[0169] Heat treatment B 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 nitrogen gas, helium gas, argon gas, or other inert gas atmosphere. Heat treatment B may be performed under reduced pressure, vacuum, or pressure. It is particularly preferable to perform heat treatment B in an oxidizing atmosphere.

[0170] Heat treatment A and heat treatment B may be carried out successively. For example, the temperature may be increased at a constant rate in heat treatment A without any time for maintaining the temperature within a predetermined range.

[0171] When the solid composition obtained in this step contains a first precursor oxide, the first precursor oxide preferably has a crystal structure different from that of the first solid electrolyte. In the present invention, the term "different" in relation to the crystal structure is a broad concept that includes not only crystal structures that are not the same type, but also crystal structures that are the same type but have at least one different lattice constant.

[0172] In particular, it is preferable that the first solid electrolyte is composed of a solid electrolyte having a cubic garnet-type crystal structure, while the crystal structure of the first precursor oxide is a tetragonal garnet-type crystal structure or a pyrochlore oxide structure.

[0173] As a result, even if the conditions of the heat treatment after this step are relaxed, for example, at a lower temperature or for a shorter time, it is possible to preferably form the first electrolyte part P11 that is made of a solid electrolyte that has excellent adhesion to the second electrolyte part P12 and the third electrolyte part P13 and that has particularly excellent properties such as ion conductivity.

[0174] The crystal structure of the first precursor oxide may be a crystal structure other than the above-mentioned tetragonal garnet-type crystal structure or pyrochlore oxide structure, for example, a cubic crystal such as a perovskite structure, a rock salt structure, a diamond structure, a fluorite structure, or a spinel structure, an orthorhombic crystal such as a ramsdellite structure, or a trigonal crystal such as a corundum structure, etc.

[0175] The crystal grain size of the first 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.

[0176] This can further reduce the melting temperature of the first precursor oxide due to the Gibbs-Thomson effect, which is a melting point drop caused by an increase in surface energy, and further relax the conditions for the heat treatment after this step. Also, the adhesion between the second electrolyte part P12 and the first electrolyte part P11, and the adhesion between the first electrolyte part P11 and the third electrolyte part P13 in the finally obtained composite P100 can be improved.

[0177] The first precursor oxide is preferably composed of a substantially single crystal structure. As a result, in the heat treatment subsequent to this step, the crystal phase transition that occurs when forming a solid electrolyte having a cubic garnet-type crystal structure is substantially limited to one time, thereby suppressing element segregation that accompanies the crystal phase transition and the generation of impurity crystals due to thermal decomposition, and further improving various properties of the first solid electrolyte.

[0178] [2-5] Third heat treatment process In this embodiment, prior to the third electrolyte part forming step described later, the active material P10 that has been subjected to the first precursor contact step described above is heated. In particular, the active material P10 that has been subjected to the first precursor contact step and the second heat treatment step is heated.

[0179] As a result, the second precursor oxide becomes a second solid electrolyte to form the second electrolyte portion P12, and the first precursor oxide becomes a first solid electrolyte to form the first electrolyte portion P11. Furthermore, even when raw materials containing oxoanions are used in the production of the complex P100, the oxoanions can usually be sufficiently removed in this step, and the content of oxoanions in the finally obtained complex P100 can be made sufficiently low, thereby improving the reliability, etc. of the complex P100.

[0180] In this step, the heat treatment is usually carried out at a temperature higher than the heat treatments in the first heat treatment step and the second heat treatment step described above.

[0181] The heating temperature in this step is, for example, preferably 700°C or more and 1000°C or less, more preferably 730°C or more and 980°C or less, and even more preferably 750°C or more and 900°C or less.

[0182] This allows the second solid electrolyte and the first solid electrolyte to be formed efficiently by heat treatment at a relatively low temperature for a relatively short time, and also allows the adhesion between the active material P10 and the second electrolyte part P12, and between the second electrolyte part P12 and the first electrolyte part P11 to be improved, thereby making it possible to increase the lithium ion conductivity of the composite P100.

[0183] The heating temperature may be changed during the third heat treatment step. For example, the third heat treatment step may have a first stage in which 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 heat treatment is performed at a relatively high temperature. In such a case, it is preferable that the maximum temperature in the third heat treatment step is within the above-mentioned range.

[0184] The heating time in the third heat treatment step is not particularly limited, but is preferably from 2 hours to 15 hours, more preferably from 4 hours to 12 hours, and even more preferably from 4 hours to 10 hours. This makes the above-mentioned effects more pronounced.

[0185] The third heat treatment step may be performed in any atmosphere, and may be performed in an oxidizing atmosphere such as air or an oxygen gas atmosphere, or in a non-oxidizing atmosphere such as nitrogen gas, helium gas, argon gas, or other inert gas atmosphere. The third heat treatment step may be performed under reduced pressure or vacuum, or under pressure.

[0186] During the third heat treatment step, the atmosphere may be maintained under substantially the same conditions, or may be changed to different conditions.

[0187] [2-6] Third electrolyte part formation process In the third electrolyte part forming step, the active material P10 that has been subjected to the second precursor contacting step and the first precursor contacting step is brought into contact with a third solid electrolyte to form a third electrolyte part P13. This results in complex P100.

[0188] Examples of methods for forming the third electrolyte portion P13 include a method of supplying a molten liquid of the third solid electrolyte to an active material P10 that has undergone a second precursor contacting step and a first precursor contacting step, and a method of melting the third solid electrolyte in a state in which the solid third solid electrolyte is brought into contact with the active material P10 that has undergone a second precursor contacting step and a first precursor contacting step, and then melting the third solid electrolyte.

[0189] When forming the third electrolyte portion P13 in this step, the third solid electrolyte is usually heated to a temperature equal to or higher than its melting point.

[0190] The heating temperature in this step varies depending on the composition of the third solid electrolyte, etc., but is preferably from (Tm+5)°C to (Tm+150)°C, more preferably from (Tm+10)°C to (Tm+100)°C, and even more preferably from (Tm+15)°C to (Tm+80)°C, where Tm is the melting point of the third solid electrolyte.

[0191] Even if the composite P100 obtained as described above is produced using a raw material containing oxoanions, the oxoanions are usually sufficiently removed in the third heat treatment step, so that the content of oxoanions in the finally obtained composite P100 is sufficiently low. More specifically, the content of oxoanions in the composite P100 is usually 100 ppm or less, preferably 50 ppm or less, and more preferably 10 ppm or less.

[0192] [3]Battery Next, the battery of the present invention will be described. The battery of the present invention includes the composite of the present invention described above, an electrode provided on one surface of the composite, and a current collector provided on the other surface of the composite.

[0193] This makes it possible to provide a battery that includes a composite in which the adhesion between the solid electrolyte and the active material and between the solid electrolytes themselves is sufficiently excellent, an increase in grain boundary resistance is suppressed, and a decrease in lithium ion conductivity is suppressed, and the discharge capacity is resistant to decrease, and in particular, the discharge capacity is suitably maintained even when the battery is repeatedly charged and discharged.

[0194] A specific configuration of a lithium ion secondary battery as the battery of the present invention will be described below.

[0195] Fig. 2 is a schematic cross-sectional view showing a typical configuration of a lithium ion secondary battery, in particular, a coin-type battery as an example of the lithium ion secondary battery.

[0196] In particular, the lithium ion battery 100 shown in Fig. 2 has the above-mentioned composite P100, the negative electrode 30 as the electrode provided in contact with one surface of the composite P100, and a current collector 41 provided in contact with the surface of the composite P100 opposite to the surface in contact with the negative electrode 30. Furthermore, the lithium ion battery 100 shown in Fig. 2 has a current collector 42 provided in contact with the surface of the negative electrode 30 opposite to the surface in contact with the composite P100. That is, the lithium ion battery 100 of this embodiment has a configuration in which the current collector 41, the composite P100, the negative electrode 30, and the current collector 42 are laminated in this order.

[0197] 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.

[0198] 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.

[0199] [3-1] Complex As described above, the composite P100 constituting the lithium-ion battery 100 comprises an active material P10, a first electrolyte part P11, and a second electrolyte part P12, with at least a portion of the first electrolyte part P11 joined to the active material P10 via the second electrolyte part P12, and in particular, the active material P10 includes a positive electrode active material.

[0200] The active material P10 may be unevenly distributed on one surface of the composite P100. In this case, it is preferable that the surface of the composite P100 opposite to the surface on which the active material P10 is unevenly distributed is in contact with the negative electrode 30. When the active material P10 is unevenly distributed on one surface of the composite P100, the first electrolyte part P11 and the third electrolyte part P13 may be unevenly distributed on the other surface.

[0201] The thickness of the composite P100 constituting the lithium ion battery 100 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.

[0202] [3-2] 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 positive electrode active material that constitutes composite P100.

[0203] The negative electrode 30 is made of a material containing a negative electrode active material. Examples of negative electrode active materials include Nb2O5, V2O5, TiO2, In2O3, ZnO, SnO2, NiO, ITO, AZO, GZO, ATO, FTO, and Li4Ti5O. 12 and lithium double oxides such as Li2Ti3O7. 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 and substances in which lithium ions are inserted between layers of carbon materials such as LiC6.

[0204] In particular, the negative electrode 30 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.

[0205] In addition, the negative electrode active material may have a coating layer formed on the surface thereof for the purpose of, for example, reducing the interfacial resistance with the solid electrolyte, improving electronic conductivity, etc. The thickness of the coating layer is not particularly limited, but is preferably 3 nm or more and 1 μm or less.

[0206] The average particle size of the negative electrode 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.

[0207] 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.

[0208] 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.

[0209] Examples of the method 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 a suitable binder, and a coating film may be formed by squeegee or screen printing, and the coating film may be dried and baked to bake it onto the surface of the composite P100.

[0210] [3-3] Current collector The current collectors 41 and 42 are conductors provided to transfer electrons to and from the composite P100 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.

[0211] 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.

[0212] The current collectors 41, 42 are usually provided so as to reduce the contact resistance with the composite P100 and the negative electrode 30, respectively. The current collectors 41, 42 may have, for example, a plate shape, a mesh shape, or the like.

[0213] 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. The lithium ion battery 100 does not necessarily have to include a pair of current collectors 41, 42; it is sufficient that the lithium ion battery 100 has at least a current collector 41 provided on one side of the composite P100, i.e., the side opposite to the side on which the negative electrode 30, which is the electrode, is provided, and does not necessarily have to have a current collector 42.

[0214] 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, .

[0215] [4]Electronic equipment Next, the electronic device of the present invention will be described. The electronic device of the present invention includes the battery of the present invention described above. This makes it possible to provide an electronic device equipped with a battery whose discharge capacity is less likely to decrease, and in particular whose discharge capacity is suitably maintained even after repeated charging and discharging.

[0216] 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.

[0217] Hereinafter, a wearable device will be described as a specific example of the electronic device of the present invention. FIG. 3 is a perspective view showing a configuration of a wearable device as an electronic device. As shown in FIG. 3, 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.

[0218] 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. 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.

[0219] 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.

[0220] 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.

[0221] 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.

[0222] 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.

[0223] 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.

[0224] 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.

[0225] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these.

[0226] For example, in the above-described embodiment, the composite has been described mainly as having a third electrolyte part in addition to an active material, a first electrolyte part, and a second electrolyte part, but the composite of the present invention does not necessarily have to have a third electrolyte part.

[0227] Furthermore, the complex of the present invention may be produced by any method, and is not limited to those produced by the methods described above.

[0228] More specifically, in the above embodiment, the first heat treatment step, the second heat treatment step, and the third heat treatment step are described as being performed three times, but the number of heat treatment steps is not limited to this, and the number of heat treatment steps may be reduced. In addition, the timing of performing the heat treatment steps is not limited to that described in the above embodiment.

[0229] In the above-described embodiment, the third electrolyte part is formed using a melt of the third solid electrolyte. However, the third electrolyte part may be formed using a precursor of the third solid electrolyte.

[0230] Furthermore, the complex of the present invention may be produced by a method having other steps in addition to the steps described above.

[0231] Furthermore, the battery of the present invention is not limited to the above-described embodiment. For example, while the battery of the above-described embodiment has a composite containing a positive electrode active material and a negative electrode as the electrode, the battery of the present invention may have a composite containing a negative electrode active material and a positive electrode as the electrode. Furthermore, the battery of the present invention may be composed of two composites, one of which contains a positive electrode active material and the other of which contains a negative electrode active material.

[0232] Furthermore, in the above-described embodiment, a coin-type battery has been representatively described, but the battery of the present invention may have a shape other than a coin type. EXAMPLES

[0233] Next, specific examples of the present invention will be described. [5] Manufacturing the composite [5-1] Preparation of metal compound solutions for use in the production of solid electrolytes First, a solution of a metal compound to be used for producing the solid electrolyte, particularly for producing the first solid electrolyte and the second solid electrolyte, was prepared as follows.

[0234] [5-1-1] Preparation of a solution of lithium nitrate in 2-n-butoxyethanol 1.3789g of 3N5 lithium nitrate manufactured by Kanto Chemical Co., Ltd. and 18.6211g of 2-normal butoxyethanol (ethylene glycol monobutyl ether) manufactured by Kanto Chemical Co., Ltd. were weighed into a 30g Pyrex (Pyrex: trademark of Corning Co., Ltd.) reagent bottle containing a magnetic stirrer. The reagent bottle was then placed on a hot plate equipped with a magnetic stirrer function, and the lithium nitrate was completely dissolved in the 2-normal butoxyethanol while stirring at 170°C for 1 hour. The mixture was then gradually cooled to room temperature to obtain a 2-normal butoxyethanol solution of lithium nitrate with a concentration of 1 mol / kg.

[0235] [5-1-2] Preparation of a solution of lanthanum nitrate in 2-n-butoxyethanol 8.6608 g of 4N lanthanum nitrate hexahydrate manufactured by Kanto Chemical Co., Ltd. and 11.3392 g of 2-n-butoxyethanol (special grade deer) manufactured by Kanto Chemical Co., Ltd. were weighed into a 30 g Pyrex (Pyrex: trademark of Corning Inc.; Pyrex and Pyrex are registered trademarks) 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 lanthanum nitrate hexahydrate in the 2-n-butoxyethanol. The solution was then gradually cooled to room temperature to obtain a 1 mol / kg lanthanum nitrate in 2-n-butoxyethanol solution.

[0236] Preparation of [5-1-3]zirconium tetra-n-butoxide in 2-n-butoxyethanol 3.8368g of zirconium tetra-n-butoxide manufactured by Kojundo Chemical Laboratory and 6.1632g of 2-n-butoxyethanol (special grade deer) manufactured by Kanto Chemical Co., Ltd. were weighed into a 20g Pyrex (Pyrex: trademark of Corning Co., Ltd.) reagent bottle containing a magnetic stirrer. The reagent bottle was then placed on a hot plate equipped with a magnetic stirrer function, 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.

[0237] [5-1-4] Preparation of gallium nitrate in ethyl alcohol 3.5470 g of gallium nitrate n-hydrate (n=5.5) manufactured by Kojundo Chemical Laboratory and 6.4530 g of ethyl alcohol that had been dehydrated in advance were weighed into a 20 g Pyrex (Pyrex: trademark of Corning Inc. Pyrex and Pyrex are registered trademarks) 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 gradually cooled to room temperature to obtain an ethyl alcohol solution of gallium nitrate with a concentration of 1 mol / 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).

[0238] [5-1-5] Preparation of calcium nitrate solution in 2-n-butoxyethanol 2.3600 g of calcium nitrate tetrahydrate from Kanto Chemical and 7.6400 g of 2-n-butoxyethanol that had been previously dehydrated were weighed into a 20 g Pyrex (Pyrex: trademark of Corning Inc.; Pyrex and Pyrex are registered trademarks) reagent bottle containing a magnetic stirrer. The bottle was then placed on a hot plate equipped with a magnetic stirrer 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 solution of calcium nitrate in 2-n-butoxyethanol.

[0239] Preparation of a solution of [5-1-6]niobium pentan-n-butoxide in 2-n-butoxyethanol 4.5848 g of niobium penta normal butoxide manufactured by Kojundo Chemical Laboratory Co., Ltd. and 5.4152 g of deer-grade 2-normal butoxyethanol manufactured by Kanto Chemical Co., Ltd. were weighed into a 20 g Pyrex (Pyrex: trademark of Corning Corporation. Pyrex and Pyrex are registered trademarks) reagent bottle containing a magnetic stirrer. Next, the reagent bottle was placed on a hot plate equipped with a magnetic stirrer function, and the niobium penta normal butoxide was completely dissolved in the 2-normal butoxyethanol while stirring at room temperature for 30 minutes, to obtain a 1 mol / kg concentration solution of niobium penta normal butoxide in 2-normal butoxyethanol.

[0240] Preparation of a solution of [5-1-7]tantalum pentaethoxide in 2-n-butoxyethanol 5.4640 g of tantalum pentaethoxide manufactured by Kojundo Chemical Laboratory and 4.5360 g of deer-grade 2-normal butoxyethanol manufactured by Kanto Chemical Co., Ltd. were weighed into a 20 g Pyrex (Pyrex: trademark of Corning Inc.; Pyrex and Pyrex are registered trademarks) reagent bottle containing a magnetic stirrer. The reagent bottle was then placed on a hot plate equipped with a magnetic stirrer function, and the tantalum pentaethoxide was completely dissolved in the 2-normal butoxyethanol while stirring at room temperature for 30 minutes, to obtain a 1 mol / kg concentration solution of tantalum pentaethoxide in 2-normal butoxyethanol.

[0241] Preparation of a solution of [5-1-8]antimony tri-n-butoxide in 2-n-butoxyethanol 3.4110 g of antimony tri-n-butoxide manufactured by Wako Pure Chemical Industries, Ltd. and 6.5890 g of deer-grade 2-n-butoxyethanol manufactured by Kanto Chemical Co., Ltd. were weighed into a 20 g Pyrex (Pyrex: trademark of Corning Inc. Pyrex and Pyrex are registered trademarks) reagent bottle containing a magnetic stirrer. Next, the reagent bottle was placed on a hot plate equipped with a magnetic stirrer function, and the antimony tri-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 antimony tri-n-butoxide with a concentration of 1 mol / kg.

[0242] [5-2] Manufacturing the composite (Example A1) First, a composition for forming a second solid electrolyte and a composition for forming a first solid electrolyte were prepared using the solution prepared in [5-1] above.

[0243] The composition for forming the second solid electrolyte was prepared by mixing the solutions prepared in [5-1-1], [5-1-2], [5-1-3], [5-1-7] and [5-1-8] above, and Triton (registered trademark) X-100 (manufactured by MP Biomedicals, Inc.) as a nonionic surfactant in a predetermined ratio.

[0244] The composition for forming the first solid electrolyte was prepared by mixing the solutions prepared in [5-1-1], [5-1-2], [5-1-3], [5-1-4] and [5-1-5] above, and Triton (registered trademark) X-100 (manufactured by MP Biomedicals, Inc.) as a nonionic surfactant in a predetermined ratio.

[0245] A LiCoO2 pellet, which is a positive electrode active material, was placed on a hot plate via a silicon substrate. The LiCoO2 pellet used was a rectangular solid pellet measuring 10 mm x 10 mm x 0.1 mm.

[0246] Using a micropipette, 15 μL of the composition for forming the second solid electrolyte was dropped onto the top surface of the LiCoO2 pellet. As a result, the composition for forming the second solid electrolyte penetrated into the LiCoO2 pellet by capillary action and spread to completely cover the pellet.

[0247] Next, the temperature of the hot plate was raised to 90° C. and kept at that temperature for 15 minutes to volatilize the solvent of the composition for forming the second solid electrolyte.

[0248] The hot plate was then heated to 360°C and held there for 10 minutes to combust and decompose the organic components. This heat treatment resulted in the formation of a second precursor oxide with a pyrochlore oxide crystal structure.

[0249] Then, 20 μL of the composition for forming the first solid electrolyte was dropped onto the top surface of the LiCoO2 pellet on which the second precursor oxide was provided, using a micropipette. As a result, the composition for forming the first solid electrolyte penetrated into the LiCoO2 pellet on which the second precursor oxide was provided by capillary action, and spread to completely cover the pellet.

[0250] Next, the temperature of the hot plate was raised to 90° C. and kept at that temperature for 15 minutes to volatilize the solvent of the above-mentioned first solid electrolyte-forming composition.

[0251] The hot plate was then heated to 360°C and held there for 10 minutes to combust and decompose the organic components. This heat treatment resulted in the formation of a first precursor oxide having a pyrochlore oxide crystal structure. The steps of dropping the composition for forming the first solid electrolyte, volatilizing the solvent by heating, and combusting and decomposing the organic components were repeated a total of 20 times.

[0252] Next, the mixture was subjected to a calcination treatment, which was a heat treatment at 900°C for 8 hours. As a result, the second precursor oxide became the second solid electrolyte, and the first precursor oxide became the first solid electrolyte. The second solid electrolyte was Li 6.30 La3Zr 1.30 Sb0.50 Ta 0.20 O 12 and has a cubic garnet type crystal structure. The first solid electrolyte is Li 5.51 Ga 0.50 La 2.99 Ca 0.01 ZrO 12 and had a cubic garnet type crystal structure.

[0253] Next, the LiCoO pellets on which the second solid electrolyte and the first solid electrolyte were formed were coated with an amorphous third solid electrolyte, Li 2.2 C 0.8 B 0.2 The composite was obtained by impregnating the molten LiO3 solution into the composite and then cooling it to room temperature. 2.2 C 0.8 B 0.2 The melting point of O3 is 685°C, and the temperature of the melt of the third solid electrolyte during impregnation was 725°C.

[0254] (Examples A2 to A6) Composites were produced in the same manner as in Example A1, except that the compositions for forming the second solid electrolyte and the compositions for forming the first solid electrolyte were adjusted by adjusting the types and amounts of the solutions prepared in the above [5-1].

[0255] (Example A7) A composite was produced in the same manner as in Example A3, except that no amorphous third solid electrolyte was added after the firing treatment at 900° C. for 8 hours. That is, the composite of this example has an active material, a first electrolyte part, and a second electrolyte part, but does not have a third electrolyte part.

[0256] (Example A8) First, a composition for forming a second solid electrolyte and a composition for forming a first solid electrolyte were prepared using the solution prepared in [5-1] above.

[0257] The composition for forming the second solid electrolyte was prepared by mixing the solutions prepared in [5-1-1], [5-1-2], [5-1-3], [5-1-7] and [5-1-8] above, and Triton (registered trademark) X-100 (manufactured by MP Biomedicals, Inc.) as a nonionic surfactant in a predetermined ratio.

[0258] The composition for forming the first solid electrolyte was prepared by mixing the solutions prepared in [5-1-1], [5-1-2], [5-1-3], [5-1-4] and [5-1-5] above, and Triton (registered trademark) X-100 (manufactured by MP Biomedicals, Inc.) as a nonionic surfactant in a predetermined ratio.

[0259] The composition for forming the second solid electrolyte was placed in a Pyrex (Pyrex: trademark of Corning Inc. Pyrex and Pyrex are registered trademarks) reagent bottle, and LiCoO2 powder, which is the positive electrode active material, was added thereto. The average particle size of the LiCoO2 powder was 5.5 μm.

[0260] The reagent bottle was immersed in an ultrasonic cleaner containing water and ultrasonic waves were applied to disperse the LiCoO2 powder.

[0261] After that, the excess second solid electrolyte forming composition was removed using a centrifuge, and the LiCoO2 powder with the second solid electrolyte forming composition attached to its surface was transferred to a titanium petri dish with an inner diameter of 50 mm and a depth of 20 mm, and heated on a hot plate. At this time, the mixture was heated at 90°C for 30 minutes to volatilize the solvent contained in the second solid electrolyte forming composition, and then heated at 360°C for 30 minutes to burn and decompose the organic components. This heat treatment formed a second precursor oxide with a pyrochlore oxide crystal structure.

[0262] Thereafter, the LiCoO2 powder coated with the second precursor oxide as described above was poured into a Pyrex (Pyrex: trademark of CORNING Inc.; Pyrex is a registered trademark) reagent bottle containing the above-mentioned composition for forming the first solid electrolyte.

[0263] The reagent bottle was immersed in an ultrasonic cleaner containing water and ultrasonic waves were applied to disperse the powder of LiCoO2 coated with the second precursor oxide.

[0264] After that, the excess first solid electrolyte-forming composition was removed using a centrifuge, and the LiCoO2 powder coated with the second precursor oxide and the first solid electrolyte-forming composition attached to its surface was transferred to a titanium petri dish with an inner diameter of 50 mm and a depth of 20 mm, and heated on a hot plate. At this time, the mixture was heated at 90°C for 30 minutes to volatilize the solvent contained in the first solid electrolyte-forming composition, and then heated at 360°C for 30 minutes to burn and decompose the organic components. This heat treatment formed a first precursor oxide with a pyrochlore oxide crystal structure.

[0265] Next, using a mold with an inner diameter of 10 mm and an exhaust port, the LiCoO2 powder coated with the second precursor oxide and the first precursor oxide was pressed at a pressure of 624 MPa for 2 minutes to obtain a disk-shaped molded product with a diameter of 10 mm, an effective diameter of 8 mm, and a thickness of 150 μm.

[0266] The disk-shaped product thus obtained was subjected to a calcination treatment, which was a heat treatment at 900°C for 8 hours, whereby the second precursor oxide became the second solid electrolyte and the first precursor oxide became the first solid electrolyte. The second solid electrolyte was Li 6.30 La3Zr 1.30 Sb 0.50 Ta 0.20 O 12 and has a cubic garnet type crystal structure. The first solid electrolyte is Li 5.51 Ga 0.50 La 2.99 Ca 0.01 ZrO 12 and had a cubic garnet type crystal structure.

[0267] Next, the disk-shaped molded product on which the second solid electrolyte and the first solid electrolyte were formed as described above was coated with an amorphous third solid electrolyte, Li 2.2C 0.8 B 0.2 The composite was obtained by impregnating the molten LiO3 solution into the composite and then cooling it to room temperature. 2.2 C 0.8 B 0.2 The melting point of O3 is 685°C, and the temperature of the melt of the third solid electrolyte during impregnation was 725°C.

[0268] (Examples A9 to A12) A composite was produced in the same manner as in Example A8, except that the composition for forming the second solid electrolyte and the composition for forming the first solid electrolyte were adjusted by adjusting the type and amount of the solution prepared in the above [5-1].

[0269] (Example A13) A composite was produced in the same manner as in Example A10, except that no amorphous third solid electrolyte was added after the firing treatment at 900° C. for 8 hours. That is, the composite of this example has an active material, a first electrolyte part, and a second electrolyte part, but does not have a third electrolyte part.

[0270] (Example A14) First, a composition for forming a second solid electrolyte and a composition for forming a first solid electrolyte were prepared using the solution prepared in [5-1] above.

[0271] The composition for forming the second solid electrolyte was prepared by mixing the solutions prepared in [5-1-1], [5-1-2], [5-1-3], [5-1-7] and [5-1-8] above, and Triton (registered trademark) X-100 (manufactured by MP Biomedicals, Inc.) as a nonionic surfactant in a predetermined ratio.

[0272] The composition for forming the first solid electrolyte was prepared by mixing the solutions prepared in [5-1-1], [5-1-2], [5-1-3], [5-1-4] and [5-1-5] above, and Triton (registered trademark) X-100 (manufactured by MP Biomedicals, Inc.) as a nonionic surfactant in a predetermined ratio.

[0273] A LiCoO2 chip (manufactured by Toshima Manufacturing Co., Ltd., 50 mm square, 1 mm thick) was prepared as a positive electrode active material, and the composition for forming the second solid electrolyte was applied to one side of the chip using a doctor blade. As a result, the composition for forming the second solid electrolyte penetrated into the LiCoO2 chip by capillary action and spread to completely cover the chip.

[0274] Next, the LiCoO2 chip coated with the above-mentioned composition for forming a second solid electrolyte was placed on a hot plate via a silicon substrate, and the hot plate was heated to 90°C and held for 15 minutes to volatilize the solvent of the above-mentioned composition for forming a second solid electrolyte.

[0275] The hot plate was then heated to 360°C and held there for 10 minutes to combust and decompose the organic components. This heat treatment resulted in the formation of a second precursor oxide with a pyrochlore oxide crystal structure.

[0276] Then, the composition for forming the first solid electrolyte was applied to one side of the LiCoO2 chip on which the second precursor oxide was formed as described above using a doctor blade. As a result, the composition for forming the first solid electrolyte penetrated into the LiCoO2 chip by capillary action and spread to completely cover the entire surface.

[0277] Next, the temperature of the hot plate was raised to 90° C. and kept at that temperature for 15 minutes to volatilize the solvent of the above-mentioned first solid electrolyte-forming composition.

[0278] The hot plate was then heated to 360°C and held there for 10 minutes to combust and decompose the organic components. This heat treatment resulted in the formation of a first precursor oxide with a pyrochlore oxide crystal structure.

[0279] Next, the mixture was subjected to a calcination treatment, which was a heat treatment at 900°C for 8 hours. As a result, the second precursor oxide became the second solid electrolyte, and the first precursor oxide became the first solid electrolyte. The second solid electrolyte was Li 6.30 La3Zr 1.30 Sb 0.50 Ta 0.20 O 12 and has a cubic garnet type crystal structure. The first solid electrolyte is Li 5.51 Ga 0.50 La 2.99 Ca 0.01 ZrO 12 and had a cubic garnet type crystal structure.

[0280] Next, the LiCoO2 chip on which the second solid electrolyte and the first solid electrolyte were formed was coated with an amorphous third solid electrolyte, Li 2.2 C 0.8 B 0.2 The composite was obtained by impregnating the molten LiO3 solution into the composite and then cooling it to room temperature. 2.2 C 0.8 B 0.2 The melting point of O3 is 685°C, and the temperature of the melt of the third solid electrolyte during impregnation was 725°C.

[0281] (Examples A15 to A18) A composite was produced in the same manner as in Example A14, except that the composition for forming the second solid electrolyte and the composition for forming the first solid electrolyte were adjusted by adjusting the type and amount of the solution prepared in the above [5-1].

[0282] (Example A19) A composite was produced in the same manner as in Example A16, except that no amorphous third solid electrolyte was applied after the firing treatment at 900° C. for 8 hours. That is, the composite of this example has an active material, a first electrolyte part, and a second electrolyte part, but does not have a third electrolyte part.

[0283] (Comparative Example A1) A composite was produced in the same manner as in Example A3, except that the steps of applying a composition for forming a second solid electrolyte to the positive electrode active material and forming a second precursor oxide by heat treatment of the positive electrode active material to which the composition for forming a second solid electrolyte had been applied were omitted. That is, the composite of this comparative example has an active material, a first electrolyte part, and a third electrolyte part, but does not have a second electrolyte part.

[0284] (Comparative example A2) A composite was produced in the same manner as in Comparative Example A1, except that the amorphous third solid electrolyte was not applied after the firing treatment at 900° C. for 8 hours. That is, the composite of this comparative example has an active material and a first electrolyte part, but does not have a second electrolyte part or a third electrolyte part.

[0285] (Comparative example A3) A composite was produced in the same manner as in Comparative Example A1, except that the composition of the composition for forming the first solid electrolyte was adjusted by adjusting the type and amount of the solution prepared in the above [5-1].

[0286] (Comparative example A4) Li 5.75 La3Zr 0.75 Nb 0.35 Sb 0.50 Ta 0.40 O 12 A composite was produced in the same manner as in Example A4, except that a coating composed of LiAlO2 was formed instead of the second solid electrolyte having the composition.

[0287] The formation of the coating composed of LiAlO2 was carried out in the same manner and under the same conditions as in Example 1, except that a composition for forming LiAlO2 was used instead of the composition for forming the second solid electrolyte.

[0288] (Comparative examples A5~A12) A composite was produced in the same manner as in Example A1, except that the composition of the composition for forming the first solid electrolyte was adjusted by adjusting the type and amount of the solution prepared in the above [5-1], and the heating temperature in the firing treatment.

[0289] The conditions of the composites in each of the examples and comparative examples, and the heating temperature in the firing process, i.e., the firing temperature, are shown in Figs. 4 and 5. In Figs. 4 and 5, LiCoO2 is shown as "LCO", and the ratio of each part constituting the composite in the composite is shown as "occupancy rate". In addition, the composites obtained in each of the examples and comparative examples all had a solvent content of 0.1 mass% or less and an oxoanion content of 100 ppm or less. In each of the examples, the crystal grain size of the first precursor oxide and the second precursor oxide formed in the manufacturing process of the composite was 20 nm or more and 160 nm or less. In each of the composites obtained in the examples, the second electrolyte part was formed in a film shape on the surface of the positive electrode active material, and the average thickness of the second electrolyte part was 0.004 μm or more and 0.080 μm or less.

[0290] [6] Evaluation of the complex For the composites of each of the Examples and Comparative Examples obtained as described above, the lithium ion conductivity was evaluated as an index of lithium ion conductivity by the following method. That is, lithium electrodes (ion-activated electrodes) of 8 mm diameter were prepared on both the front and back sides of the composite by lithium vapor deposition. Then, AC impedance measurement was performed using an impedance analyzer SI1260 (Solartron). The AC amplitude during measurement was 10 mV, and the measurement frequency was 10 7 Hz to 10 -1 The frequency was set to Hz.

[0291] These results are summarized in Figures 6 and 7. As is clear from FIGS. 6 and 7, excellent results were obtained in the present invention, whereas satisfactory results were not obtained in the comparative example.

[0292] [7] Battery manufacturing Example B1 A lithium negative electrode was formed on one surface of the composite prepared in Example A1 by vacuum deposition, and the thickness of the negative electrode was 20 μm.

[0293] Next, a copper current collector was formed on each side of the laminate of the composite and the negative electrode by vacuum sputtering, to obtain a battery. The current collector had a thickness of 10 μm.

[0294] (Examples B2 to B19) Batteries were produced in the same manner as in Example B1, except that the composites produced in Examples A2 to A19 were used, respectively.

[0295] (Comparative examples B1~B12) Batteries were produced in the same manner as in Example B1, except that the composites produced in Comparative Examples A1 to A12 were used, respectively.

[0296] [8] Battery evaluation Immediately after production, the batteries of Examples B1 to B19 and Comparative Examples B1 to B12 obtained as described above were connected to a battery charge / discharge evaluation system HJ1001SD8 manufactured by Hokuto Denko Corporation, and repeatedly charged and discharged under the conditions shown in Figs. 8 and 9 to evaluate the first and tenth charge / discharge characteristics of the batteries.

[0297] These results, together with the charge / discharge conditions, are shown in Figures 8 and 9. Note that the "discharge capacity retention rate" in Figures 8 and 9 indicates the ratio of the 10th discharge capacity to the 1st discharge capacity.

[0298] As is clear from FIGS. 8 and 9, excellent results were obtained in the present invention, whereas satisfactory results were not obtained in the comparative example. [Explanation of symbols]

[0299] P100...composite, P10...active material, P11...first electrolyte part, P12...second electrolyte part, P13...third electrolyte part, 100...lithium ion battery, 30...negative electrode, 41...current collector, 42...current collector, 300...wearable device, 301...band, 302...sensor, 303...display part, 304...processing part, WR...wrist

Claims

1. An active material; A crystalline first electrolyte portion including a lithium composite metal oxide represented by the following composition formula (1); A second electrolyte portion containing a lithium composite metal oxide represented by the following composition formula (2) and covering at least a part of the surface of the active material, a composite body, wherein at least a portion of the first electrolyte portion is bonded to the active material via the second electrolyte portion. (Li ７－３ｘ＋ｙ Ga ｘ )(La ３－ｙ Ca ｙ )Zr ２ O １２ ・・・(1) (However, in formula (1), the relationships 0.10≦x≦1.00 and 0.00<y≦0.30 are satisfied.) <h2 style=";text-align:left;direction:ltr">Li<h2 style=";text-align:left;direction:ltr"> ７－ｚ <h2 style=";text-align:left;direction:ltr"> La<h2 style=";text-align:left;direction:ltr"> ３ <h2 style=";text-align:left;direction:ltr"> ((Zr<h2 style=";text-align:left;direction:ltr"> ２－ｚ <h2 style=";text-align:left;direction:ltr"> 8<h2 style=";text-align:left;direction:ltr"> ｚ <h2 style=";text-align:left;direction:ltr"> )O<h2 style=";text-align:left;direction:ltr"> １２ <h2 style=";text-align:left;direction:ltr">・・・(22) (In formula (2), element M is two or more elements selected from the group consisting of Nb, Ta, and Sb, and satisfies the relationship 0.00<z<2.00.)

2. The composite according to claim 1 , further comprising an amorphous third electrolyte portion containing Li in contact with the first electrolyte portion.

3. The composite according to claim 2 , wherein the third electrolyte portion contains Li, B, and O.

4. The composite according to claim 1 , wherein the active material is a positive electrode active material containing Li.

5. A composite according to any one of claims 1 to 4, An electrode provided on one surface side of the composite body; and a current collector provided on the other surface side of the composite.

6. An electronic device comprising the battery according to claim 5.

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