Composite, lithium ion conductor, all-solid-state lithium ion secondary battery, electrode sheet for all-solid-state lithium ion secondary battery, lithium tetraborate

Abstract

The present application provides a composite capable of forming a lithium ion conductor showing good lithium ion conductivity by a pressurization treatment without sintering at high temperature (around 1000°C) while using a lithium-containing oxide, a lithium ion conductor, a full solid-state lithium ion secondary battery, an electrode sheet for a full solid-state lithium ion secondary battery, and lithium tetraborate. The composite of the present application contains: a lithium compound having a lithium ion conductivity of 1.0 x 10 ‑6 S / cm or more at 25°C; and lithium tetraborate satisfying the following requirement 1. Requirement 1: in a reduced pair distribution function G(r) obtained from X-ray total scattering measurement of the lithium tetraborate, a first peak having a peak top in a range where r is and a second peak having a peak top in a range where r is exist, G(r) at the peak top of the first peak and G(r) at the peak top of the second peak show more than 1.0, and in a range where r is more than and below, the absolute value of G(r) is less than 1.0.

Description

TECHNICAL FIELD

[0001] The present application relates to a composite, a lithium ion conductor, an all-solid-state lithium ion secondary battery, an electrode sheet for an all-solid-state lithium ion secondary battery, and lithium tetraborate. BACKGROUND

[0002] In the past, a lithium ion secondary battery has used a liquid electrolyte having high lithium ion conductivity. However, since the liquid electrolyte is flammable, there is a problem in safety. Also, since it is liquid, it is difficult to downsize, and when the battery is upsized, the limitation on capacity becomes a problem.

[0003] In view of this, an all-solid-state lithium ion secondary battery is one of new-generation batteries that can solve these problems. In an all-solid-state battery, in order to obtain desired charge and discharge characteristics, a solid electrolyte having good lithium ion conductivity is required. For example, a solid electrolyte that can be used for an all-solid-state lithium ion secondary battery is disclosed in Patent Literature 1. In Patent Literature 1, a solid electrolyte based on a lithium-containing oxide is disclosed.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 2013-140762 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] On the other hand, in the case of using a lithium-containing oxide as described in Patent Literature 1, in order to be molded, a high-temperature firing process of about 1000°C is required, and there is room for improvement in productivity.

[0009] Therefore, if a material of a lithium ion conductor that can show good lithium ion conductivity by a pressurization process without sintering at a high temperature while using a lithium-containing oxide excellent in safety and stability, then a solid electrolyte excellent in safety and stability can be produced with good productivity, and thus is preferred.

[0010] In view of the above actual situation, the present application aims to provide a composite of a lithium ion conductor that can show good lithium ion conductivity by a pressurization process without sintering at a high temperature (about 1000°C) while using a lithium-containing oxide.

[0011] Also, the present application aims to provide a lithium ion conductor, an all-solid-state lithium ion secondary battery, an electrode sheet for an all-solid-state lithium ion secondary battery, and lithium tetraborate.

[0012] MEANS FOR SOLVING THE PROBLEMS

[0013] As a result of intensive studies made by the present inventors and others in order to solve the above problems, the present invention has been completed.

[0014] (1) A composite comprising:

[0015] a lithium compound having a lithium ion conductivity of 1.0 x 10- 6 S / cm or more at 25°C; and

[0016] lithium tetraborate satisfying a requirement 1 described later.

[0017] (2) The composite according to (1), wherein,

[0018] the solid 7 the full width at half maximum of the peak having a chemical shift in the range of -100 to +100 ppm in the spectrum obtained at the time of Li-NMR measurement is 120°C or less. 7 the proportion of the full width at half maximum of the peak having a chemical shift in the range of -100 to +100 ppm in the spectrum obtained at the time of Li-NMR measurement is 70% or less.

[0019] (3) The composite according to (1) or (2), wherein,

[0020] the lithium tetraborate has a volume elastic modulus of 45 GPa or less.

[0021] (4) The composite according to any one of (1) to (3), wherein,

[0022] the lithium compound is a lithium-containing oxide.

[0023] (5) The composite according to any one of (1) to (4), wherein,

[0024] the lithium compound comprises at least one selected from the group consisting of: a lithium compound having a garnet-type structure or a garnet-type structure-like structure containing at least Li, La, Zr, and O, a lithium compound having a perovskite-type structure containing at least Li, Ti, La, and O, a lithium compound having a NASICON-type structure containing at least Li, M 1 , P, and O, and M 1 representing at least one of Ti, Zr, and Ge, a lithium compound having an amorphous structure containing at least Li, P, O, and N, a lithium compound having a monoclinic structure containing at least Li, Si, and O, a lithium compound represented by LiM 2 X 1 O4, when M 2 represents a divalent element or a trivalent element, M 2 represents a divalent element, X1 represents a pentavalent element, when M 2 represents a trivalent element, X 1 represents a lithium compound having an olivine-type structure, at least containing Li, O, and X 2 , X 2 represents a lithium compound having an inverse perovskite structure, at least containing Li, O, and X 3 Y4represents, M 3 represents a lithium compound having a spinel structure, at least containing Li, O, and X

[0025] (6) A lithium ion conductor formed using the composite body described in any one of (1) to (5).

[0026] (7) The lithium ion conductor according to (6), which satisfies the following requirement 2 or requirement 3.

[0027] (8) A full solid-state lithium ion secondary battery, which successively has a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer, wherein

[0028] At least one of the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer contains the lithium ion conductor described in (6) or (7).

[0029] (9) An electrode sheet for a full solid-state lithium ion secondary battery, which contains the lithium ion conductor described in (6) or (7).

[0030] (10) A lithium tetraborate, which satisfies the following requirement 1.

[0031] (11) The lithium tetraborate according to (10), wherein

[0032] The half-height full width of a peak in which a chemical shift in a spectrum obtained at 20°C under solid 7 The half-height full width of a peak in which a chemical shift in a spectrum obtained at 120°C under solid 7 The proportion of the half-height full width of a peak in which a chemical shift in a spectrum obtained at 20°C under solid

[0033] (12) The lithium tetraborate according to (10) or (11), wherein

[0034] The coefficient of determination obtained by linear regression analysis using a least squares method in a wave number range of 600 to 850 cm 1 -1 of a Raman spectrum is 0.9400 or more.

[0035] Effects of Invention

[0036] According to the present application, it is possible to provide a composite of a lithium ion conductor having high lithium ion conductivity, which is formed by pressurization only, without sintering at high temperature (around 1000°C) while using a lithium oxide-containing compound.

[0037] Further, according to the present application, it is also possible to provide a lithium ion conductor, a full solid-state lithium ion secondary battery, an electrode sheet for a full solid-state lithium ion secondary battery, and lithium tetraborate. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a graph showing an example of a reduced pair distribution function G(r) obtained by X-ray total scattering measurement of the second lithium compound.

[0039] Figure 2 is a graph showing an example of an X-ray total scattering profile of the second lithium compound.

[0040] Figure 3 is a graph showing an example of a structure factor S(Q) based on the X-ray total scattering profile obtained in Figure 2

[0041] Figure 4 is a graph showing an example of a solid-state NMR spectrum of the second lithium compound measured at 20°C or 120°C. 7 is a graph showing an example of a spectrum obtained at the time of Li-NMR measurement.

[0042] Figure 5 is a graph showing an example of a solid-state NMR spectrum of lithium tetraborate crystal measured at 20°C or 120°C. 7 is a graph showing an example of a spectrum obtained at the time of Li-NMR measurement.

[0043] Figure 6 is a graph showing an example of a Raman spectrum of the second lithium compound.

[0044] Figure 7 is a graph showing a Raman spectrum of general lithium tetraborate crystal.

[0045] Figure 8 is a graph showing an example of a Raman spectrum of the first lithium compound and the second lithium compound in the lithium ion conductor.

[0046] Figure 9 is a cross-sectional view schematically showing a full solid-state lithium ion secondary battery according to a preferred embodiment of the present application. DETAILED DESCRIPTION

[0047] Hereinafter, the present application will be described in detail.

[0048] ​In addition, in the present specification, a numerical range represented by "to" means a range including the numerical values recited before and after "to" as lower limit values and upper limit values.

[0049] Also, in the present specification, the expression of a compound (for example, when called with a compound attached at the end) means to include a salt thereof, an ion thereof, in addition to the compound itself. Also, it means to include a derivative in which a part of a substituent or the like is changed within a range not impairing the effects of the present application.

[0050] As a feature point of the composite of the present application, the following aspects can be cited: the use of a lithium compound showing a prescribed lithium ion conductivity and lithium tetraborate showing a prescribed property. As described later, lithium tetraborate showing a prescribed property has a short-range ordered structure, but hardly has a long-range ordered structure. Therefore, the obtained lithium tetraborate is softer than the conventional lithium-containing oxides, and shows a property of easily being plastically deformed. If a composite containing such lithium tetraborate and a lithium compound having a high lithium ion conductivity is subjected to a pressurization treatment, since the lithium tetraborate is plastically deformed between the lithium compounds at the same time, it functions to connect the lithium compounds to each other, and thus a lithium ion conductor having a low porosity and showing a good lithium ion conductivity is easily obtained.

[0051] In addition, as a prior art, although there is a method of using a lithium halide instead of the lithium tetraborate showing a prescribed property used in the present application, the lithium halide represented by lithium iodide is easily oxidized and decomposed in the presence of air, compared to lithium tetraborate, and a more special apparatus is required in the manufacturing process of the all-solid-state lithium ion secondary battery. Also, it is difficult to use on the positive electrode side of the battery due to the oxidation reaction of the lithium halide.

[0052] Furthermore, as a prior art, as a lithium compound easily plastically deformed, a sulfide-based lithium compound can be cited, but these compounds can generate hydrogen sulfide.

[0053] The composite of the present application contains a lithium compound having a lithium ion conductivity of 1.0 x 10 -6 at 25°C (hereinafter, also simply referred to as "1st lithium compound") and lithium tetraborate satisfying prescribed requirements (hereinafter, also simply referred to as "2nd lithium compound").

[0054] Hereinafter, each component contained in the composite will be described in detail.

[0055] <1st lithium compound>

[0056] The composite contains a lithium compound having a lithium ion conductivity of 1.0 x 10 -6a lithium compound (1st lithium compound) having a lithium ion conductivity of 1.0 x 10"6S / cm or more. By incorporating the above 1st lithium compound into a composite, a lithium ion conductor obtained using the composite exhibits excellent lithium ion conductivity.

[0057] The kind of the 1st lithium compound is not particularly limited, and the lithium ion conductivity at 25°C is preferably 1.0 x 10"6S / cm or more, and more preferably 1.0 x 10"5S / cm or more. -6 S / cm or more. The lithium ion conductivity at 25°C of the 1st lithium compound is preferably 1.0 x 10"6S / cm or more, and more preferably 1.0 x 10"5S / cm or more. -5 S / cm or more. The upper limit is not particularly limited, but is generally 1.0 x 10"5S / cm or less. -3 S / cm or less.

[0058] In the above method for measuring the lithium ion conductivity, Au electrodes are arranged above and below the 1st lithium compound, the measurement temperature is set to 25°C, the applied voltage is set to 100 mV, and the measurement frequency range is set to 1 Hz to 1 MHz, and the arc diameter of the Cole-Cole curve obtained by alternating current impedance measurement is calculated.

[0059] From the viewpoint that the lithium ion conductivity of the lithium ion conductor obtained by pressure molding the composite is more excellent (hereinafter, also referred to simply as "the more excellent viewpoint of the effects of the present application"), the 1st lithium compound is preferably a compound selected from the group consisting of Compounds 1 to 9 below.

[0060] Compound 1: a lithium compound having a garnet-type structure or a structure similar to a garnet-type structure, containing at least Li, La, Zr, and O

[0061] Compound 2: a lithium compound having a perovskite-type structure, containing at least Li, Ti, La, and O

[0062] Compound 3: a lithium compound containing at least Li, M 1 , P, and O, M 1 represents at least one of Ti, Zr, Si, and Ge and has a NASICON-type structure

[0063] Compound 4: a lithium compound having an amorphous structure, containing at least Li, P, O, and N

[0064] Compound 5: a lithium compound having a monoclinic structure, containing at least Li, Si, and O

[0065] Compound 6: a lithium compound represented by LiM 2 X 1 O4, M 2 represents a divalent element or a trivalent element, X 2 represents a divalent element, X 1 represents a pentavalent element, and X 2 represents a trivalent element, X 1Lithium compounds represented by Li

[0066] In addition, as the M 2 represented by M 2 represented by M 1 represented by X 1 represented by X

[0067] Compound 7: A lithium compound containing at least Li, O, and X 2 , X 2 represented by at least one of Cl, Br, N, and I, and having an inverse perovskite structure

[0068] Compound 8: A lithium compound represented by Li2M 3 Y4 represents, M 3 represented by at least one of Cd, Mg, Mn, and V, Y represents at least one of F, Cl, Br, and I, and has a spinel structure.

[0069] Compound 9: A lithium compound having a β-alumina structure.

[0070] As the above-mentioned compound 1, for example, a compound represented by Li7La3Zr2O 12 (hereinafter, also referred to as "LLZO") and a compound in which Ta, Al, Ga, Nb, Ba, Rb, Sc, or Y, or the like is doped in LLZO.

[0071] As the above-mentioned compound 2, for example, a compound represented by Li 3x La 2 / 3-x TiO3 and Li 3x La 2 / 3-x TiO3 to which Sr, Zr, or Hf, or the like is doped.

[0072] As the above-mentioned compound 3, for example, LiGe2(PO4)3 and LiTi2(PO4)3, and a compound in which Si, Al, or Cr, or the like is doped in them.

[0073] As the above-mentioned compound 4, for example, LiPON (Li x PO y N z , x = 2y + 3z - 5).

[0074] As the monoclinic crystal structure in the above-mentioned compound 5, a NASICON-type structure and a garnet-type structure can be given. Further, as the above-mentioned compound 5, for example, a compound obtained by doping Zn, Cr, Sn, Zr, or Al, or the like in Li4SiO4and Li4SiO4can be given. Also, the above-mentioned compound 5 (particularly Li4SiO4) is preferably a compound for which a space group is designated as P121 / m1.

[0075] As the above-mentioned compound 6, for example, LiInSiO4, LiInGeO4, LiScGeO4, and LiMgAsO4can be given.

[0076] As the above-mentioned compound 7, for example, Li3OCl, Li3OCl 0.5 Br 0.5 and a compound obtained by doping Ba or Sr, or the like therein can be given.

[0077] As the above-mentioned compound 8, for example, Li2CdCl4, Li2MgCl4, Li2MnCl4, and Li2VCl4can be given.

[0078] As the above-mentioned compound 9, for example, Li-β-alumina, the composition of which is represented by (Li2O) x • 11Al2O3, x is, for example, a Li compound having a value of 0.9 to 1.3.

[0079] Among them, as the first lithium compound, a lithium-containing oxide is preferable. The lithium-containing oxide refers to an oxide containing a lithium element.

[0080] The bulk modulus of the first lithium compound is not particularly limited, and from the viewpoint of more excellent effects of the present application, it is preferably 50 to 300 GPa, and more preferably 100 to 200 GPa.

[0081] The measurement of the above-mentioned bulk modulus is performed by an ultrasonic attenuation method.

[0082] Specifically, first, a suspension obtained by suspending the first lithium compound is prepared. The content of the first lithium compound in the suspension is set to 1.2 mass% with respect to the total mass of the suspension. Next, the ultrasonic attenuation spectrum of the above-mentioned suspension is measured, and the bulk modulus of the first lithium compound is calculated by fitting according to a scattering attenuation theory formula. Further, in performing the above-mentioned fitting, the particle size distribution, the density, and the Poisson's ratio of the first lithium compound are used. For example, in the case of LLZO, the density is 4.97 g / ml, and the Poisson's ratio is 0.257.

[0083] As to the fitting by the above scattering attenuation theory formula, the bulk modulus was calculated using the formulae (7), (12), and (13) described in Kohjiro Kubo et al., Ultrasonics 62 (2015) 186-194.

[0084] Further, the particle size distribution of the first lithium compound is obtained by flow particle image analysis to obtain a histogram (particle size distribution) of the particle size of the first lithium compound. The above particle size corresponds to the equivalent circle diameter.

[0085] The median particle size (D50) of the first lithium compound is not particularly limited, and from the viewpoint of more excellent effects of the present application, it is preferably 0.1 to 100 μm, and more preferably 1 to 20 μm.

[0086] The measurement method of the above average particle size is obtained by flow particle image analysis to obtain a particle image, calculate the particle size distribution of the first lithium compound, and analyze the obtained distribution.

[0087] The first lithium compound can be produced by a publicly known method, and commercially available products can be used.

[0088] The content of the first lithium compound in the composite is not particularly limited, but from the viewpoint of excellent effects of the present application and more excellent processability of the composite, it is preferably 50 to 97% by mass, and more preferably 70 to 95% by mass, relative to the total mass of the composite.

[0089] <2nd Lithium Compound>

[0090] The composite contains lithium tetraborate (the second lithium compound) satisfying the following requirement 1. As described above, the second lithium compound is easily plastically deformed, and as a result, the processability of the composite is improved.

[0091] The second lithium compound (lithium tetraborate) contained in the composite of the present application is generally a compound represented by Li2B4O7, and is a compound mainly composed of Li, B, and O, but in the present application, it can deviate from the above standard values. More specifically, as the second lithium compound contained in the composite of the present application, it is preferably a compound represented by Li 2+x B 4+y O 7+z (-0.3 < x < 0.3, -0.3 < y < 0.3, -0.3 < z < 0.3).

[0092] Further, the above-mentioned second lithium compound can also be doped with an element other than Li, B and O. That is, the second lithium compound can be lithium tetraborate doped with an element selected from the group consisting of C, Si, P, S, Se, Ge, F, Cl, Br, I, N, Al, Ga and In. Thus, the second lithium compound can be lithium tetraborate doped with an element selected from the group consisting of C, Si, P, S, Se, Ge, F, Cl, Br, I, N, Al, Ga and In, represented by Li 2+x B 4+y O 7+z (-0.3 < x < 0.3, -0.3 < y < 0.3, -0.3 < z < 0.3) indicates a compound.

[0093] The second lithium compound satisfies the following requirement 1.

[0094] Requirement 1: In a reduced pair distribution function G(r) obtained by X-ray total scattering measurement of the second lithium compound (lithium tetraborate), there are a first peak having a peak top at r in the range of 1.43 ± 0.05 A and a second peak having a peak top at r in the range of 2.40 ± 0.05 A, G(r) at the peak top of the first peak and G(r) at the peak top of the second peak show more than 1.0, and the absolute value of G(r) is less than 1.0 in the range where r is more than 3.0 A and

[0095] Hereinafter, requirement 1 will be described using Figure 1 .

[0096] An example of a reduced pair distribution function G(r) obtained by X-ray total scattering measurement of the second lithium compound is shown in Figure 1 .The vertical axis of the graph of G(r) is a reduced pair distribution function obtained by Fourier transformation of X-ray scattering, and indicates the probability that there is an atom at a position of distance r. Figure 1

[0097] The X-ray total scattering measurement was performed at SPring-8 BL04B2 (acceleration voltage 61.4 keV, wavelength ).

[0098] Further, the scattering intensity I obtained by experiment is converted to obtain a reduced pair distribution function G(r) by the following steps.

[0099] First, the scattering intensity I obs is represented by formula (1). Further, a structure factor S(Q) is obtained by dividing I coh by the product of the number of atoms N and the atomic scattering factor f.

[0100] I obs = I​​​​coh +I incoh +I 荧光 (1)

[0101] [Formula 1]

[0102]

[0103] PDF (Pair Distribution Function) analysis requires the use of the structure factor S(Q). In equation (2) above, the required intensity is only the coherent scattering I. coh Incoherent scattering I incoh and fluorescent X-ray I 荧光 It is possible to determine the scattering intensity I through blank measurement, derivation of theoretical formulas, and detector discriminator. obs Subtract from the middle. An example of the total scattering measurement results and the extracted structure factor S(Q) of the second lithium compound is shown below. Figure 2 and Figure 3 .

[0104] Coherent scattering is represented by Debye's scattering equation (3) (N: total number of atoms, f: atomic scattering factor, r ij (The interatomic distance between :ij).

[0105] [Formula 2]

[0106]

[0107] If we consider any atom and define the atomic density at a distance r as ρ(r), then the number of atoms existing within a sphere of radius r - r + d(r) is 4πr. 2 ρ(r)dr, therefore equation (3) is expressed by equation (4).

[0108] [Formula 3]

[0109]

[0110] Let the average density of atoms be ρ0. Equation (4) is transformed to obtain equation (5).

[0111] [Formula 4]

[0112]

[0113] Equation (6) is obtained from equations (5) and (2).

[0114] [Formula 5]

[0115]

[0116] The two-body distribution function g(r) is represented by equation (7).

[0117] [Formula 6]

[0118]

[0119] The formula (8) is obtained from the above formula (6) and formula (7).

[0120] [Formula 7]

[0121]

[0122] As described above, the pair distribution function can be obtained by Fourier transform of the structure factor S(Q). In order to easily observe the order in the long distance, the pair distribution function is transformed into G(r) = 4πr(g(r) - 1) to obtain the reduced pair distribution function (g(r)). Figure 1 The g(r) that vibrates around 0 indicates the density difference from the average density in the interatomic distance of each atom, and is higher than 1 of the average density when there is a correlation in a specific interatomic distance. Therefore, it reflects the distance and coordination number of the element corresponding to the local to the medium distance. If the order disappears, ρ(r) approaches the average density, and therefore g(r) approaches 1. Therefore, in the amorphous structure, the larger r is, the order disappears, and therefore g(r) is 1, that is, G(r) is 0.

[0123] In the requirement 1, as shown in Figure 1 , in the reduced pair distribution function G(r) obtained by the X-ray total scattering measurement, there is a first peak P1 in which the peak top is in the range of r = 1.43 ± , and a second peak P2 in which the peak top is in the range of r = 2.40 ± , and G(r) of the peak top of the first peak P1 and G(r) of the peak top of the second peak P2 exceed 1.0.

[0124] That is, in the reduced pair distribution function G(r) obtained by the X-ray total scattering measurement of the second lithium compound, it is observed that G(r) of the peak top (hereinafter, also referred to as "first peak top") shows more than 1.0, and the first peak in which the first peak top is in the range of r = 1.43 ± , and G(r) of the peak top (hereinafter, also referred to as "second peak top") shows more than 1.0, and the second peak in which the second peak top is in the range of r = 2.40 ± .

[0125] In addition, in the Figure 1 , the peak top of the first peak P1 is in the range of , the peak top of the second peak P2 is in the range of

[0126] In the position of , there is a peak attributed to the interatomic distance of B (boron) -O (oxygen). And, in the In the position of r = 4.2 A, there is a peak attributed to the interatomic distance of B (boron) - B (boron). That is, the observation of the above two peaks (the 1st peak and the 2nd peak) means that the periodic structure corresponding to the above two interatomic distances exists in the 2nd lithium compound.

[0127] Also, in the requirement 1, as shown in FIG. 2, the absolute value of G(r) is less than 1.0 (corresponding to the dotted line) in the range of r exceeding Figure 1 and The following range, the absolute value of G(r) is less than 1.0 (corresponding to the dotted line) in the range of r exceeding

[0128] As described above, the absolute value of G(r) is less than 1.0 in the range of r exceeding and The following range, the absolute value of G(r) is less than 1.0 means that the long-range ordered structure hardly exists in the 2nd lithium compound.

[0129] As described above, the 2nd lithium compound satisfying the above requirement 1 has the short-range ordered structure related to the interatomic distances of B-O and B-B, but hardly has the long-range ordered structure. Therefore, the 2nd lithium compound itself shows the elastic property of easy plastic deformation, and as a result, a composite capable of being formed by pressurization treatment or the like can be obtained.

[0130] In addition, in the above reduced pair distribution function G(r), a peak other than the 1st peak and the 2nd peak can exist in the range of r being

[0131] In addition, the 2nd lithium compound can have a crystalline component within a range not obstructing the effects of the present application. Among them, when the 2nd lithium compound is analyzed by X-ray diffraction method using CuKa rays, the intensity of the strongest of the crystalline diffraction lines found in the range of 2Θ values of 20 to 25° is preferably 5 times or less, more preferably 3 times or less, the intensity of the diffraction line at the apex of the broad scattering band found in the range of 2Θ values of 10 to 40°.

[0132] In addition, the 2nd lithium compound preferably does not have a crystalline diffraction line observed in the range of 2Θ values of 20 to 25° from the viewpoint of more excellent effects of the present application.

[0133] Also, from the viewpoint of more excellent effects of the present application, the solid 7 The half width of the peak in which the chemical shift in the spectrum obtained at the time of Li-NMR measurement appears in the range of -100 to +100 ppm is 0.2 ppm or less at 20°C, and 0.1 ppm or less at 120°C. 7 ​​The proportion of the half-peak full width of the peak appearing in the chemical shift in the spectrum obtained at the time of Li-NMR measurement in the range of -100 to +100 ppm is preferably 70% or less, more preferably 50% or less. The lower limit is not particularly limited and is usually 10% or more.

[0134] The half-peak full width (FWHM) of the peak refers to the width (ppm) at the position of 1 / 2 of the height (H) of the peak (H / 2).

[0135] Hereinafter, the following Figure 4 will be described.

[0136] In Figure 4 , the spectrum shown by the solid line on the lower side is the spectrum obtained by solid 7 Li-NMR measurement at 20°C.

[0137] Figure 4 The spectrum shown by the solid line on the lower side in 7 is the spectrum obtained by solid 7 Li-NMR measurement at 120°C. Figure 4

[0138] Generally, in solid 7 Li-NMR measurement, when the mobility of Li + is high, the obtained peak is sharper. In the manner shown in Figure 4 , when the spectrum at 20°C and the spectrum at 120°C are compared, the spectrum at 120°C becomes sharper. That is, it is shown in the second lithium compound in Figure 4 that the mobility of Li + is increased due to the presence of Li defects and the like. It is considered that such a second lithium compound is derived from a defect structure as described above, is easily plastically deformed, and the jumping property of Li + is excellent, and thus the effects of the present application are more excellent.

[0139] In addition, regarding a general lithium tetraborate crystal, when solid 7 Li-NMR measurement is performed at 20°C or 120°C, Figure 5 the spectrum measured at 20°C shown by the solid line on the lower side and the spectrum measured at 120°C shown by the broken line on the upper side in Figure 5 easily form approximately the same shape. That is, in the lithium tetraborate crystal, there are no Li defects and the like, and as a result, the elastic modulus is high and it is not easy to be plastically deformed.

[0140] The solid 7 Li-NMR measurement conditions are as follows.​

[0141] Specifically, the measurement was performed using a 4 mm HX CP-MAS probe, in a single pulse method, 90° pulse width: 3.2 μs, observation frequency: 155.546 MHz, observation width: 1397.6 ppm, repetition time: 15 sec, accumulation: 1 time, MAS rotation speed: 0 Hz.

[0142] Also, from the viewpoint of more excellent effects of the present application, the second lithium compound preferably satisfies the following requirement 4.

[0143] Requirement 4: The coefficient of determination obtained by linear regression analysis using the least squares method in the wave number range of 600 to 850 cm -1 of the Raman spectrum of the second lithium compound is 0.9400 or more.

[0144] In addition, from the viewpoint of more excellent effects of the present application, the coefficient of determination in the above requirement 4 is more preferably 0.9600 or more. There is no particular limitation on the upper limit, and 1.0000 can be given.

[0145] Hereinafter, the above requirement 4 will be described. Figure 6

[0146] An example of the Raman spectrum of the second lithium compound is shown in Figure 6 . In the frequency range of 600 to 850 cm -1 of the Raman spectrum in which the vertical axis is the Raman intensity and the horizontal axis is the Raman shift, the coefficient of determination (coefficient of determination R 2 ) obtained by linear regression analysis using the least squares method is calculated. That is, in the frequency range of 600 to 850 cm -1 of the Raman spectrum of Figure 4 , a regression line (a broken line thick line in Figure 4 ) is found by the least squares method, and the coefficient of determination R 2 of the regression line is calculated. In addition, the coefficient of determination takes a value between 0 (no linear correlation) and 1 (perfect linear correlation of the measured values) depending on the linear correlation of the measured values.

[0147] In the second lithium compound, as shown in Figure 6 , almost no peak is seen in the frequency range of 600 to 850 cm -1 , and as a result, a high coefficient of determination is shown.

[0148] In addition, the above coefficient of determination R 2 corresponds to the square of the correlation coefficient (Pearson product-moment correlation coefficient). More specifically, in the present specification, the coefficient of determination R 2 ​In the formula, x1 and y1 represent the wavenumber and the corresponding Raman intensity in the Raman spectrum, x2 represents the (arithmetic) average of the wavenumbers, and y2 represents the (arithmetic) average of the Raman intensities.

[0149] [Formula 8]

[0150]

[0151] on the other hand, Figure 7 The image shows the Raman spectrum of typical lithium tetraborate crystals. (Example:) Figure 7 As shown, in the case of typical lithium tetraborate crystallization, the crystals originating from this structure at 716–726 cm⁻¹ -1 and 771~785cm -1 A peak was observed in the frequency domain.

[0152] When such a peak exists, it is between 600 and 850 cm⁻¹. -1 In the frequency domain, when using the least squares method to perform linear regression analysis to calculate the coefficient of determination, the coefficient of determination is less than 0.9400.

[0153] That is, a determination coefficient of 0.9400 or higher indicates that the second lithium compound contains almost no crystalline structure typical of lithium tetraborate crystals. Therefore, the results suggest that the second lithium compound exhibits readily malleable properties and Li... + It has excellent jumping ability.

[0154] Furthermore, as a method for measuring Raman spectra under condition 4 above, a method for measuring Raman spectra implemented under condition 2 described later can be cited as an example.

[0155] There is no particular limitation on the bulk modulus of the second lithium compound, but from the viewpoint of better performance of the present invention, it is preferably 45 GPa or less, more preferably 40 GPa or less. There is no particular limitation on the lower limit, but it is preferably 5 GPa or more.

[0156] The method for determining the bulk elastic modulus described above is the same as the method for determining the bulk elastic modulus of the first lithium compound.

[0157] There is no particular limitation on the median particle size (D50) of the second lithium compound, but from the viewpoint of better performance of the present invention, it is preferably 0.05 to 8.0 μm, more preferably 0.5 to 4.0 μm, and even more preferably 0.1 to 2.0 μm.

[0158] The method for determining the median particle size described above is the same as the method for determining the median particle size of the first lithium compound.

[0159] There are no particular restrictions on the method of manufacturing the second lithium compound, as long as lithium tetraborate exhibiting the above-mentioned properties can be obtained.

[0160] Among them, from the viewpoint of being able to produce the second lithium compound at a good productivity, a method of performing mechanical polishing treatment on lithium tetraborate crystals can be cited.

[0161] The lithium tetraborate crystal (LBO crystal) used is a crystal in which an XRD pattern attributed to space group I41cd is observed when XRD measurement is performed on lithium tetraborate.

[0162] The mechanical polishing treatment is a treatment in which pulverization is performed while mechanical energy is imparted to a sample.

[0163] As the mechanical polishing treatment, for example, a ball mill, a vibration mill, a turbo mill, and a disc-type vibration mill can be cited, and from the viewpoint of being able to produce the second lithium compound at a good productivity, a ball mill is preferred. As the ball mill, for example, a vibration ball mill, a rotary ball mill, and a planetary ball mill can be cited, and a planetary ball mill is more preferred.

[0164] As the conditions of the ball mill treatment, the optimum conditions are selected depending on the raw material used.

[0165] The material of the pulverizing balls (media) used at the time of the ball milling is not particularly limited, and for example, agate, silicon nitride, zirconia, alumina, and iron-based alloys can be cited, and from the viewpoint of being able to produce the second lithium compound at a good productivity, zirconia is preferred.

[0166] The average particle diameter of the pulverizing balls is not particularly limited, and from the viewpoint of being able to produce the second lithium compound at a good productivity, 1 to 10 mm is preferred, and 3 to 7 mm is more preferred. The above average particle diameter is obtained by measuring the diameters of an arbitrary 50 pulverizing balls and performing arithmetic mean. If the pulverizing balls are not spherical, the long diameter is taken as the diameter.

[0167] The number of the pulverizing balls used at the time of the ball milling is not particularly limited, and from the viewpoint of being able to produce the second lithium compound at a good productivity, 10 to 100 is preferred, and 40 to 60 is more preferred.

[0168] The material of the pulverizing tank used at the time of the ball milling is not particularly limited, and for example, agate, silicon nitride, zirconia, alumina, and iron-based alloys can be cited, and from the viewpoint of being able to produce the second lithium compound at a good productivity, zirconia is preferred.

[0169] The rotation speed at the time of the ball milling is not particularly limited, and from the viewpoint of being able to produce the second lithium compound at a good productivity, 200 to 700 rpm is preferred, and 350 to 550 rpm is more preferred.

[0170] The processing time of the ball mill is not particularly limited, but is preferably 10 to 200 hours, more preferably 20 to 140 hours, from the viewpoint of being able to produce the second lithium compound at a good productivity.

[0171] The atmosphere during the ball milling can be under the atmosphere or under an inert gas atmosphere (e.g., argon, helium, and nitrogen).

[0172] The content of the second lithium compound in the composite is not particularly limited, and is preferably 3 to 50% by mass, more preferably 5 to 30% by mass, relative to the total mass of the composite, from the viewpoint of the lithium ion conductivity of the lithium ion conductor obtained by using the composite being more excellent and the viewpoint of the processing and molding of the composite being more excellent.

[0173] The mixing ratio of the first lithium compound to the second lithium compound in the composite is not particularly limited, and the content ratio of the second lithium compound to the first lithium compound (mass of the second lithium compound / mass of the first lithium compound) is not particularly limited, and is preferably 1 / 20 to 1 / 1, more preferably 1 / 20 to 1 / 2, further preferably 1 / 16 to 1 / 3, from the viewpoint of the effects of the present application being more excellent.

[0174] <Other materials>

[0175] The composite can contain other components in addition to the above-described first lithium compound and second lithium compound.

[0176] The composite can contain a binder.

[0177] As the binder, various organic high molecular compounds (polymers) can be given.

[0178] The organic high molecular compound constituting the binder can be in a particulate form or in a non-particulate form. The particle diameter (volume average particle diameter) of the particulate binder is preferably 10 to 1000 nm, more preferably 20 to 750 nm, further preferably 30 to 500 nm, further preferably 50 to 300 nm.

[0179] The type of the binder is not particularly limited, and the following polymers can be given, for example.

[0180] As the fluorine-containing polymer, polytetrafluoroethylene, polyvinylidene fluoride, and a copolymer of polyvinylidene fluoride and hexafluoropropylene can be given, for example.

[0181] As the hydrocarbon-based thermoplastic polymer, polyethylene, polypropylene, styrene butadiene rubber, hydrogenated styrene butadiene rubber, butylene rubber, acrylonitrile-butadiene rubber, polybutadiene, and polyisoprene can be given, for example.

[0182] As the acrylic polymer, various (meth)acrylic monomers, (meth)acrylamide monomers, and copolymers of monomers constituting these polymers (preferably, a copolymer of acrylic acid and methyl acrylate) can be exemplified.

[0183] Further, a copolymer (copolymer) with other ethylene-based monomers is also preferably used. For example, a copolymer of methyl (meth)acrylate and styrene, a copolymer of methyl (meth)acrylate and acrylonitrile, and a copolymer of butyl (meth)acrylate and acrylonitrile and styrene can be exemplified.

[0184] As the other polymers, for example, polyurethane, polyurea, polyamide, polyimide, polyester, polyether, polycarbonate, and cellulose derivatives can be exemplified.

[0185] Among them, an acrylic polymer, polyurethane, polyamide, or polyimide is preferable.

[0186] The polymer constituting the adhesive can use a polymer synthesized by a conventional method, or a commercially available product.

[0187] The adhesive can be used alone, or two or more kinds can be used in combination.

[0188] When the composite contains the adhesive, the content of the adhesive is preferably 0.1 to 3% by mass, and more preferably 0.5 to 1% by mass, relative to the total mass of the composite.

[0189] The composite can contain a lithium salt.

[0190] The lithium salt is not particularly limited, and for example, the lithium salt described in paragraphs 0082 to 0085 of Japanese Patent Application Publication No. 2015-088486 is preferable.

[0191] As the lithium salt, the following are specifically exemplified.

[0192] (L-1) Inorganic lithium salt: Inorganic fluoride salts such as LiPF6, LiBF4, LiAsF6, and LiSbF6; high halide salts such as LiClO4, LiBrO4, and LiIO4; inorganic chloride salts such as LiAlCl4.

[0193] (L-2) Fluorine-containing organic lithium salt: LiCF3SO3 and the like perfluoroalkylsulfonate; LiN(CF3SO2)2, LiN(CF3CF2SO2)2, LiN(FSO2)2, and LiN(CF3SO2)(C4F9SO2) and the like perfluoroalkylsulfonimide; LiC(CF3SO2)3 and the like perfluoroalkylsulfonmethide; Li[PF5(CF2CF2CF3)], Li[PF4(CF2CF2CF3)2], Li[PF3(CF2CF2CF3)3], Li[PF5(CF2CF2CF2CF3)], Li[PF4(CF2CF2CF2CF3)2], and Li[PF3(CF2CF2CF2CF3)3] and the like fluoroalkyl fluorophosphate.

[0194] (L-3) Oxalate borate: lithium bis(oxalato)borate, lithium difluoro(oxalato)borate.

[0195] In addition to the above, LiF, LiCl, LiBr, LiI, Li2SO4, LiNO3, Li2CO3, CH3COOLi, LiAsF6, LiSbF6, LiAlCl4, LiB(C6H5)4, and the like can be mentioned.

[0196] Among them, LiPF6, LiBF4, LiAsF6, LiSbF6, LiClO4, Li(R f1 SO3), LiN(R f1 SO2)2, LiN(FSO2)2, or LiN(R f1 SO2)(R f2 SO2) are preferable. f1 SO2)2, LiN(FSO2)2, or LiN(R f1 SO2)(R f2 SO2) are more preferable.

[0197] Among them, R f1 and R f2 each independently represent a perfluoroalkyl group.

[0198] The lithium salt can be used alone or in combination of two or more.

[0199] When the composite contains the lithium salt, the content of the lithium salt is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, preferably 10% by mass or less, more preferably 5% by mass or less, further preferably 3% by mass or less, and particularly preferably 1% by mass or less, relative to the total mass of the composite.

[0200] The composite can contain a lithium compound other than the first lithium compound and the second lithium compound.

[0201] Further, the composite can contain a solid electrolyte other than the first lithium compound and the second lithium compound.

[0202] < Lithium ion conductor >

[0203] The lithium ion conductor of the present application (hereinafter, also simply referred to as "specific conductor") is formed using the above-mentioned composite.

[0204] The method for forming the specific conductor using the composite is not particularly limited, and a method in which the composite is subjected to a pressurization treatment to form the specific conductor can be generally mentioned. That is, the lithium ion conductor of the present application is preferably a lithium ion conductor formed by subjecting the composite to a pressurization treatment (press molding treatment).

[0205] Hereinafter, the method for the pressurization treatment will be described in detail.

[0206] The method for the pressurization treatment is not particularly limited, and a method using a publicly known press device can be mentioned.

[0207] The pressure at the time of the pressurization treatment is not particularly limited, and the optimum pressure is selected depending on the components in the composite, but from the viewpoint of more excellent effects of the present application, it is preferably 5 to 1500 MPa, and more preferably 10 to 600 MPa.

[0208] The time for the pressurization treatment is not particularly limited, and from the viewpoint of more excellent effects of the present application and the viewpoint of productivity, it is preferably 0.01 to 0.5 hours, and more preferably 0.1 to 0.2 hours.

[0209] Further, a heating treatment can also be performed at the time of the pressurization treatment. The heating temperature at the time of the heating treatment is not particularly limited, and it is preferably 40 to 400°C, and more preferably 200 to 350°C. The heating time at the time of the heating treatment is preferably 1 minute to 6 hours.

[0210] The atmosphere in the pressurization is not particularly limited, and it can be an atmosphere under atmospheric pressure, under dry air (dew point of -20°C or lower), and under an inert gas (for example, argon, helium, and nitrogen).

[0211] The lithium ion conductivity of the lithium ion conductor of the present application is not particularly limited, and from the viewpoint of application to various uses, it is preferably 1.0 x 10 -6 S / cm or more, and more preferably 1.0 x 10 -5 S / cm or more.

[0212] The lithium ion conductor of the present application contains the first lithium compound and the second lithium compound.

[0213] The mixing ratio of the first lithium compound to the second lithium compound in the lithium ion conductor is not particularly limited, and the content ratio (mass of the second lithium compound / mass of the first lithium compound) of the second lithium compound to the first lithium compound in the lithium ion conductor is not particularly limited from the viewpoint of more excellent lithium ion conductivity of the lithium ion conductor, and is preferably 1 / 20 to 1 / 1, more preferably 1 / 20 to 1 / 2, and further preferably 1 / 16 to 1 / 3.

[0214] The lithium ion conductor of the present application preferably satisfies the following requirements 2 or 3 from the viewpoint of more excellent lithium ion conductivity.

[0215] Requirement 2: the Raman intensity at 1000 cm -1 in the Raman spectrum of lithium tetraborate in the lithium ion conductor is 1.6 times or more of the Raman intensity at 1800 cm -1 in the Raman spectrum.

[0216] Requirement 3: the determination coefficient obtained by linear regression analysis using the least squares method in the wave number range of 600 to 850 cm -1 in the Raman spectrum of the second lithium compound (lithium tetraborate) in the lithium ion conductor is 0.9000 or more.

[0217] Hereinafter, requirements 2 and 3 will be described in detail.

[0218] First, requirement 2 will be described in detail.

[0219] In requirement 2, first, the Raman spectrum of the first lithium compound and the second lithium compound in the lithium ion conductor is obtained. As the measurement method of the Raman spectrum, Raman imaging is performed. Raman imaging is a microscopic spectroscopic method combining microscopy and Raman spectroscopy. Specifically, it is a method in which the distribution of components and the like is visualized by scanning the excitation light on the sample to detect the measurement light containing Raman scattered light, and visualizing the intensity of the measurement light.

[0220] As the measurement conditions of Raman imaging, the excitation light is set to 532 nm, the objective lens is set to 100 times, the mapping method is point scanning, the step size is 1 μm, the exposure time per 1 point is set to 1 second, the number of accumulations is set to 1, and the measurement range is set to a range of 70 μm x 50 μm.

[0221] Further, principal component analysis (PCA) processing is performed on the data of the Raman spectrum to remove noise. Specifically, in the principal component analysis processing, the spectrum is recombined using components having an autocorrelation coefficient of 0.6 or more.

[0222] Next, the Raman intensity in 1000 cm -1 and 1800 cm -1 in the obtained Raman spectrum of the first lithium compound and the second lithium compound is read.

[0223] Figure 8 The figure shows an example of the Raman spectra of a first lithium compound and a second lithium compound in a lithium-ion conductor. The solid line at the bottom of the figure is the Raman spectrum of the first lithium compound, and the solid line at the top of the figure is the Raman spectrum of the second lithium compound.

[0224] like Figure 8 As shown, the 1000 cm⁻¹ value of the Raman spectrum is read with the vertical axis representing Raman intensity and the horizontal axis representing Raman shift. -1 and 1800cm -1 Raman intensity in.

[0225] In requirement 2, the Raman spectrum of the second lithium compound at 1800 cm⁻¹ -1 Raman intensity in 1000 cm -1 The Raman intensity in [the sample] is more than 1.60 times that of [the lithium-ion conductor]. Considering the superior ionic conductivity of lithium-ion conductors, the above [comparison / conversion rate] is [significantly higher than that of 1800 cm⁻¹]. -1 Raman intensity / 1000cm -1 The Raman intensity is preferably 1.70 times or higher. There is no particular upper limit, and it is usually below 2.50 times.

[0226] Typically, in Raman spectroscopy, when the analyte exhibits fluorescence, the slope of the background in the Raman spectrum tends to be positive. That is, as mentioned above, at 1800 cm⁻¹... -1 Raman intensity / 1000cm -1 The high Raman intensity indicates that the second lithium compound exhibits fluorescence properties. This fluorescence is almost unobservable in typical lithium tetraborate crystals and is a unique property of the second lithium compound. The detailed reasons why the second lithium compound exhibits the aforementioned fluorescence properties are not yet clear, but it is speculated that it is due to a different crystal structure than typical lithium tetraborate crystals, resulting in new excitation energy levels. Therefore, when the second lithium compound exhibits this fluorescence, it indicates that it originates from a different crystal structure, making it easier to plastically deform and providing excellent conductivity for Li ions.

[0227] Next, requirement 3 will be explained in detail.

[0228] In requirement 3, the Raman spectrum of the second lithium compound in the lithium-ion conductor is first obtained. The method for obtaining the Raman spectrum is the same as that for obtaining the Raman spectrum under requirement 2 above.

[0229] Next, the Raman spectrum of the second lithium compound obtained was calculated from 600 to 850 cm⁻¹. -1 The coefficient of determination is obtained by linear regression analysis using the least squares method within the wavenumber range. The method for calculating the coefficient of determination is the same as that for calculating the coefficient of determination under condition 4 above.

[0230] In the requirement 3, the above-mentioned coefficient of determination (coefficient of determination R 2 ) is 0.9000 or more. Among them, from the viewpoint of more excellent ion conductivity of the lithium ion conductor, 0.9300 or more is preferable. There is no particular limitation on the upper limit, and 1.0000 can be cited.

[0231] As described above, the above-mentioned coefficient of determination is a prescribed value or more, indicating that the second lithium compound hardly contains the crystal structure contained in the general lithium tetraborate crystal. Therefore, the second lithium compound is easily deformed and the conductivity of Li + is also excellent, and as a result, the lithium ion conductor is more excellent.

[0232] <Usage>

[0233] The composite and the lithium ion conductor of the present application can be used for various uses.

[0234] For example, it can be used for various batteries (for example, all-solid-state lithium ion secondary batteries, solid oxide type fuel cells, solid oxide water vapor electrolysis). Among them, the composite and the lithium ion conductor of the present application are preferably used for all-solid-state lithium ion secondary batteries.

[0235] More specifically, the composite of the present application is preferably used as a solid electrolyte contained in a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in an all-solid-state lithium ion secondary battery. Also, the lithium ion conductor of the present application is preferably used as a solid electrolyte contained in a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in an all-solid-state lithium ion secondary battery.

[0236] <Solid electrolyte layer-forming composition>

[0237] The composite of the present application is preferably used as a component of a solid electrolyte layer-forming composition. That is, the solid electrolyte layer-forming composition of the present application contains the above-mentioned composite.

[0238] The composite contained in the solid electrolyte layer-forming composition is as described above.

[0239] The solid electrolyte layer-forming composition can contain other components in addition to the composite.

[0240] As the other components, the above-mentioned binder and lithium salt can be cited.

[0241] The solid electrolyte layer-forming composition can contain other solid electrolytes in addition to the composite. The other solid electrolytes refer to solid electrolytes that can move ions inside them. As the solid electrolytes, inorganic solid electrolytes are preferable. Since inorganic solid electrolytes are generally solid in a stable state, they are generally not dissociated or free as cations and anions.

[0242] As other solid electrolytes, sulfide-based inorganic solid electrolytes, oxide-based inorganic solid electrolytes, halide-based inorganic solid electrolytes, and hydride-based solid electrolytes can be given.

[0243] Further, the solid electrolyte layer-forming composition can contain a dispersion medium.

[0244] As the dispersion medium, various organic solvents can be given, for example. As the organic solvent, alcohol compounds, ether compounds, amide compounds, amine compounds, ketone compounds, aromatic compounds, aliphatic compounds, nitrile compounds, and ester compounds can be given. Among them, ether compounds, ketone compounds, aromatic compounds, aliphatic compounds, or ester compounds are preferable.

[0245] The boiling point of the dispersion medium at normal pressure (1 atm) is preferably 50°C or higher, more preferably 70°C or higher. The upper limit is preferably 250°C or lower, further preferably 220°C or lower.

[0246] The above dispersion medium can be used singly or in combination of two or more.

[0247] The content of the dispersion medium in the solid electrolyte layer-forming composition is not particularly limited, and is preferably 1% by mass or more, more preferably 20% by mass or more, further preferably 25% by mass or more, particularly preferably 30% by mass or more, with respect to the total mass of the solid electrolyte layer-forming composition, and is preferably 99% by mass or less, more preferably 80% by mass or less, further preferably 75% by mass or less, particularly preferably 70% by mass or less.

[0248] The method of forming the solid electrolyte layer using the above solid electrolyte layer-forming composition is not particularly limited, and a method of coating the solid electrolyte layer-forming composition and performing pressurization treatment on the formed coating film can be given.

[0249] The coating method of the solid electrolyte layer-forming composition is not particularly limited, and spraying, spin coating, dip coating, slit coating, stripe coating, aerosol deposition method, sol-gel, and bar coating can be given, for example.

[0250] Further, after coating the solid electrolyte layer-forming composition, drying treatment can be performed on the coating film as needed. The drying temperature is not particularly limited, and as the lower limit, 30°C or higher, more preferably 60°C or higher, further preferably 80°C or higher is preferable. As the upper limit of the drying temperature, 300°C or lower, more preferably 250°C or lower is preferable.

[0251] The method of pressurization treatment on the coating film is not particularly limited, and a method using a publicly known press device (for example, a hydraulic cylinder press) can be given.

[0252] The pressure during the pressure treatment is not particularly limited, and is preferably 5 to 1500 MPa, and more preferably 300 to 600 MPa, from the viewpoint of more excellent lithium ion conductor of the solid electrolyte layer to be formed.

[0253] The time of the pressure treatment is not particularly limited, and is preferably 1 minute to 6 hours, and more preferably 1 to 20 minutes, from the viewpoint of more excellent lithium ion conductor of the solid electrolyte layer to be formed and the viewpoint of productivity.

[0254] Also, heating treatment can be performed during the pressure treatment. The heating temperature during the heating treatment is not particularly limited, and is preferably 30 to 300°C, and the heating time is more preferably 1 minute to 6 hours.

[0255] The atmosphere during the pressure is not particularly limited, and can be an atmosphere under atmospheric pressure, under dry air (dew point of -20°C or lower), and under an inert gas (for example, argon, helium, and nitrogen).

[0256] <Composition for electrode formation>

[0257] The composite of the present application is preferably used as a component of a composition for electrode formation. That is, the composition for electrode formation of the present application contains the above-described composite.

[0258] The composition for electrode formation of the present application contains the above-described composite and an active material.

[0259] The mixing ratio of the composite to the active material in the composition for electrode formation is not particularly limited, and the content ratio of the composite to the active material (mass of the composite / mass of the active material) is not particularly limited, and is preferably 0.01 to 50, and more preferably 0.05 to 20.

[0260] The composite contained in the composition for electrode formation is as described above.

[0261] As the active material, negative electrode active materials and positive electrode active materials can be given. Hereinafter, the active material is described in detail.

[0262] (Negative electrode active material)

[0263] The negative electrode active material is preferably a negative electrode active material capable of reversibly intercalating and deintercalating lithium ions. The negative electrode active material is not particularly limited, and for example, carbonaceous materials, oxides of metal or semimetal elements, lithium monomers, lithium alloys, and negative electrode active materials capable of forming alloys with lithium can be given.

[0264] The carbonaceous material used as the negative electrode active material refers to a material consisting essentially of carbon. For example, carbon black such as petroleum pitch, acetylene black (AB), and graphite (natural graphite and vapor-grown graphite and the like artificial graphite), and PAN (polyacrylonitrile)-based resin or furfuryl alcohol resin and the like various synthetic resins, which are subjected to carbonization, can be given.

[0265] Further, various carbon fiber-based materials such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, dehydrated PVA (polyvinyl alcohol)-based carbon fiber, lignin carbon fiber, glassy carbon fiber, and activated carbon fiber, meso-carbon microbe, graphite whisker, and platelet-shaped graphite can be given.

[0266] These carbonaceous materials are classified into a hard carbon and a graphite-based carbonaceous material by the degree of graphitization.

[0267] Further, the carbonaceous material preferably has the interlayer spacing, density, or size of crystallite described in Japanese Patent Application Publication No. 62-022066, Japanese Patent Application Publication No. 2-006856, and Japanese Patent Application Publication No. 3-045473. The carbonaceous material need not be a single material, and a mixture of natural graphite and artificial graphite described in Japanese Patent Application Publication No. 5-090844, and graphite having a coating layer described in Japanese Patent Application Publication No. 6-004516 can be used.

[0268] As the carbonaceous material, a hard carbon or graphite is preferred, and graphite is more preferred.

[0269] As the oxide of a metal element or a semi-metal element suitable for use as the negative electrode active material, there is no particular limitation as long as it is an oxide capable of intercalating and deintercalating lithium, and an oxide of a metal element (metal oxide), a composite oxide of a metal element, a composite oxide of a metal element and a semi-metal element, and an oxide of a semi-metal element (semi-metal oxide) can be given. In addition, the composite oxide of a metal element and the composite oxide of a metal element and a semi-metal element are collectively referred to as a metal composite oxide.

[0270] As these oxides, an amorphous oxide is preferred, and a reaction product of a metal element and an element of Group 16 of the periodic table, i.e., a chalcogenide is further preferred.

[0271] In the present application, the semi-metal element refers to an element exhibiting a property intermediate between a metal element and a non-semiconductor element, and generally includes six elements of boron, silicon, germanium, arsenic, antimony, and tellurium, and further includes three elements of selenium, polonium, and astatine.

[0272] Further, the amorphous material refers to a material having a broad scattering band with a peak in a region of 20 to 40° in terms of 2θ value by X-ray diffraction method using CuKα rays, and can have a crystalline diffraction line. The intensity of the strongest diffraction line in the crystalline diffraction line appearing in a region of 40 to 70° in terms of 2θ value is preferably 100 times or less, more preferably 5 times or less, and particularly preferably does not have a crystalline diffraction line, of the intensity of the diffraction line at the peak of the broad scattering band appearing in a region of 20 to 40° in terms of 2θ value.

[0273] In the compound group including the above-mentioned amorphous oxide and the above-mentioned chalcogenide, an amorphous oxide of a semi-metal element or the above-mentioned chalcogenide is more preferable, and a (composite) oxide or chalcogenide containing one kind or two or more kinds (composite) selected from the group consisting of elements of Groups 13 (IIIB) to 15 (VB) of the periodic table (for example, Al, Ga, Si, Sn, Ge, Pb, Sb, and Bi) is further preferable.

[0274] As the amorphous oxide and the chalcogenide, Ga2O3, GeO, PbO, PbO2, Pb2O3, Pb2O4, Pb3O4, Sb2O3, Sb2O4, Sb2O8, Bi2O3, Sb2O8, Si2O3, Sb2O5, Bi2O3, Bi2O4, GeS, PbS, PbS2, Sb2S3, or Sb2S5 is preferable.

[0275] As the negative electrode active material which can be used together with the amorphous oxide negative electrode active material centering on Sn, Si, or Ge, a carbonaceous material capable of intercalating and / or deintercalating lithium ions or lithium metal, a lithium monomer, a lithium alloy, or a negative electrode active material capable of alloying with lithium is preferable.

[0276] From the viewpoint of high current density charge-discharge characteristics, the oxide of a metal element or a semi-metal element (particularly a metal (composite) oxide) and the above-mentioned chalcogenide preferably contain at least one of titanium and lithium as a constituent component.

[0277] As the metal composite oxide containing lithium (lithium composite metal oxide), for example, a composite oxide of lithium oxide and the above-mentioned metal oxide, the above-mentioned metal composite oxide, or the above-mentioned chalcogenide can be given. More specifically, Li2SnO2 can be given.

[0278] The negative electrode active material (for example, metal oxide) further preferably contains a titanium element (titanium oxide). Specifically, since Li4Ti5O 12 (Lithium titanate [LTO]) has a small volume change when intercalating and deintercalating lithium ions, and thus has excellent rapid charge and discharge characteristics, and is preferable in terms of both suppressing degradation of the electrode and improving the life of the all-solid-state lithium ion secondary battery.

[0279] The lithium alloy as the negative electrode active material is not particularly limited as long as it is an alloy generally used as a negative electrode active material of a full solid-state lithium ion secondary battery, and for example, a lithium-aluminum alloy can be given.

[0280] The negative electrode active material capable of alloying with lithium is not particularly limited as long as it is a negative electrode active material generally used as a negative electrode active material of a full solid-state lithium ion secondary battery. As the negative electrode active material, a negative electrode active material (alloy) containing a silicon element or a tin element, and each metal such as Al and In can be given, and a negative electrode active material containing a silicon element capable of achieving a higher battery capacity is preferable, and a negative electrode active material containing a silicon element having a content of 50 mol% or more of all constituting elements is more preferable.

[0281] Generally, a negative electrode containing such a negative electrode active material (for example, a Si negative electrode containing a negative electrode active material containing a silicon element, a Sn negative electrode containing a negative electrode active material containing a tin element, and the like) is capable of intercalating more Li ions than a carbon negative electrode (graphite and acetylene black, and the like). That is, the amount of occlusion of Li ions per unit mass increases. Therefore, the battery capacity can be increased. As a result, it has an advantage that the battery driving time can be extended.

[0282] As the negative electrode active material containing a silicon element, for example, a silicon material such as Si, SiOx (0 < x ≤ 1), and the like, and a silicon-containing alloy (for example, LaSi2, VSi2, La-Si, Gd-Si, and Ni-Si) or a structured active material (for example, LaSi2 / Si) containing titanium, vanadium, chromium, manganese, nickel, copper, or lanthanum can be given. In addition, a negative electrode active material containing a silicon element and a tin element such as SnSiO3 and SnSiS3 can be given. In addition, SiOx can be used as a negative electrode active material itself (semimetal oxide), and Si is generated by the operation of a full solid-state lithium ion secondary battery, and thus can be used as a negative electrode active material capable of alloying with lithium (a precursor thereof).

[0283] As the negative electrode active material containing a tin element, for example, a negative electrode active material containing Sn, SnO, SnO2, SnS, SnS2, and the above-described silicon element and tin element can be given.

[0284] From the viewpoint of the battery capacity, as the negative electrode active material, a negative electrode active material capable of alloying with lithium is preferable, a silicon material or a silicon-containing alloy (an alloy containing a silicon element) described above is more preferable, and silicon (Si) or a silicon-containing alloy is further preferable.

[0285] The shape of the negative electrode active material is not particularly limited, and a particle shape is preferable. The volume average particle diameter of the negative electrode active material is not particularly limited, and 0.1 to 60 μm is preferable, 0.5 to 20 μm is more preferable, and 1.0 to 15 μm is further preferable.

[0286] The volume average particle size was determined by the following steps.

[0287] Prepare a 1% (w / w) dispersion of the negative electrode active material by diluting it with water (or heptane for substances unstable in water) in a 20 mL sample vial. Irradiate the diluted dispersion sample with ultrasound at 1 kHz for 10 minutes, and then use it immediately in the test. Using this dispersion sample, and employing a laser diffraction / scattering particle size distribution measuring device at 25°C using a measuring quartz cell, perform 50 data acquisitions to obtain the volume average particle size. Other detailed conditions should be referred to JIS Z8828:2013 "Particle size analysis - Dynamic light scattering method" as needed. Prepare 5 samples for each grade and use their average value.

[0288] A single negative electrode active material can be used alone, or two or more materials can be used in combination.

[0289] The surface of the negative electrode active material can also be coated with another metal oxide.

[0290] As surface coating agents, examples include metal oxides containing Ti, Nb, Ta, W, Zr, Al, Si, or Li. Specifically, examples include spinel titanate, tantalum oxides, niobium oxides, and lithium niobate compounds; specifically, Li₄Ti₅O₂... 12 Li2Ti2O5, LiTaO3, LiNbO3, LiAlO2, Li2ZrO3, Li2WO4, Li2TiO3, Li2B4O7, Li3PO4, Li2MoO4, Li3BO3, LiBO2, Li2CO3, Li2SiO3, SiO2, TiO2, ZrO2, Al2O3 and B2O3.

[0291] Furthermore, the electrode surface containing the negative electrode active material can be surface-treated with sulfur or phosphorus.

[0292] Furthermore, the particle surface of the negative electrode active material can be surface-treated by activating light or an active gas (e.g., plasma) before and after the aforementioned surface coating.

[0293] (Positive electrode active material)

[0294] The positive electrode active material is preferably a positive electrode active material capable of reversibly inserting and / or deintercalating lithium ions. There are no particular limitations on the positive electrode active material, but transition metal oxides are preferred, and more preferably, materials containing the transition metal element M. a A transition metal oxide (selected from one or more elements chosen from Co, Ni, Fe, Mn, Cu, and V). Furthermore, element M may also be mixed into this transition metal oxide. b(elements other than lithium, elements of Group 1 (Ia) of the periodic table of the elements, elements of Group 2 (Ha) of the periodic table of the elements, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, and B, etc.). As the mixing amount, it is preferable to mix in a manner such that the molar ratio of Li / M a is 0 to 30 mol% with respect to the amount (100 mol%) of the transition metal element M a is 0.3 to 2.2.

[0295] Specific examples of the transition metal oxide include (MA) a transition metal oxide having a layered rock-salt type structure, (MB) a transition metal oxide having a spinel type structure, (MC) a lithium-containing transition metal phosphoric compound, (MD) a lithium-containing transition metal halogenated phosphoric compound, and (ME) a lithium-containing transition metal silicic compound. Among these, (MA) a transition metal oxide having a layered rock-salt type structure is preferable, and LiCoO2or LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2.

[0296] As (MA) a transition metal oxide having a layered rock-salt type structure, for example, LiCoO2(lithium cobaltate [LCO]), LiNi2O2(lithium nickelate), LiNi 0.85 Co 0.10 Al 0.05 O2(lithium nickel cobalt aluminum [NCA]), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(lithium nickel manganese cobalt [NMC]), and LiNi 0.5 Mn 0.5 O2(lithium manganese nickelate) can be given.

[0297] As (MB) a transition metal oxide having a spinel type structure, for example, LiMn2O4(LMO), LiCoMnO4, Li2FeMn3O8, Li2CuMn3O8, Li2CrMn3O8, and Li2NiMn3O8can be given.

[0298] As (MC) a lithium-containing transition metal phosphoric compound, for example, olivine-type iron phosphates such as LiFePO4and Li3Fe2(PO4)3, iron pyrophosphates such as LiFeP2O7, cobalt phosphates such as LiCoPO4, and monoclinic NASICON-type vanadium phosphates such as Li3V2(PO4)3(lithium vanadium phosphate) can be given.

[0299] As the (MD) lithium-containing transition metal halophosphate compound, for example, there can be mentioned iron fluorophosphates such as Li2FePO4F, manganese fluorophosphates such as Li2MnPO4F, and cobalt fluorophosphates such as Li2CoPO4F.

[0300] As the (ME) lithium-containing transition metal silicate compound, for example, there can be mentioned Li2FeSiO4, Li2MnSiO4, and Li2CoSiO4.

[0301] The shape of the positive electrode active material is not particularly limited, and is preferably particulate. The volume average particle diameter of the positive electrode active material is not particularly limited, and is preferably 0.1 to 50 μm. The volume average particle diameter of the positive electrode active material particle can be measured in the same manner as the volume average particle diameter of the above-described negative electrode active material.

[0302] The positive electrode active material obtained by the calcination method can also be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, and an organic solvent.

[0303] The positive electrode active material can be surface-coated with the above-described surface-coating agent, sulfur, or phosphorus, and further with light-activated light, in the same manner as the negative electrode active material.

[0304] The positive electrode active material can be used alone or in combination with two or more kinds.

[0305] The electrode-forming composition can contain other components in addition to the composite and the active material.

[0306] The electrode-forming composition can contain a conductive aid.

[0307] As the conductive aid, a conductive aid known as a general conductive aid can be used. As the conductive aid, for example, there can be mentioned graphite-based materials such as natural graphite and artificial graphite, carbon black-based materials such as acetylene black, ketjen black, and furnace black, amorphous carbon such as needle coke, fibrous carbon such as vapor grown carbon fiber and carbon nanotube, and carbonaceous materials such as graphene and fullerene, as an electron-conducting material. Further, a conductive polymer such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyparaphenylene derivative can be used.

[0308] In addition to the above-described conductive aid, a general conductive aid not containing a carbon atom such as a metal powder or a metal fiber can also be used.

[0309] In addition, the electrically conductive aid refers to one that does not cause the intercalation and deintercalation of Li when the battery is charged and discharged, and does not function as an active material. Therefore, in the electrically conductive aid, one that can function as an active material in the active material layer when the battery is charged and discharged is classified as an active material, not an electrically conductive aid. Whether or not it functions as an active material when the battery is charged and discharged is determined by the combination with the active material, not determined in general.

[0310] Further, as the other component, the above-mentioned binder and lithium salt can be mentioned.

[0311] The electrode-forming composition can contain a dispersion medium. The kind and preferable mode of the dispersion medium are the same as those of the dispersion medium that can be contained in the above-mentioned solid electrolyte layer-forming composition.

[0312] The electrode-forming composition can contain, as the other component other than the above-mentioned components, an ionic liquid, a thickening agent, a crosslinking agent (a substance that performs crosslinking reaction by radical polymerization, polycondensation or ring-opening polymerization), a polymerization initiator (a substance that generates acid or radical by heat or light, etc.), an antifoaming agent, a leveling agent, a dehydrating agent and an antioxidant.

[0313] The method of forming the electrode (negative electrode active material layer and positive electrode active material layer) using the above-mentioned electrode-forming composition is not particularly limited, and a method of coating the electrode-forming composition and performing pressurization treatment on the formed coating film can be mentioned.

[0314] The coating method of the electrode-forming composition is not particularly limited, and, for example, a spray coating, a spin coating, a dip coating, a slit coating, a stripe coating, an aerosol deposition method, a thermal spraying and a rod coating can be mentioned.

[0315] In addition, after coating the electrode-forming composition, drying treatment can be performed on the coating film obtained as needed. The drying temperature is not particularly limited, and, as a lower limit, it is preferably 30°C or higher, more preferably 60°C or higher, and further preferably 80°C or higher. As an upper limit of the drying temperature, it is preferably 300°C or lower, and more preferably 250°C or lower.

[0316] The method of the pressurization treatment of the coating film is not particularly limited, and a method of using a publicly known press device (for example, a hydraulic cylinder press) can be mentioned.

[0317] The pressurization force at the pressurization treatment is not particularly limited, and it is preferably 5 to 1500 MPa, and more preferably 300 to 600 MPa.

[0318] The time of the pressurization treatment is not particularly limited, and, from the viewpoint of productivity, it is preferably 1 minute to 6 hours, and more preferably 1 to 20 minutes.

[0319] Also, a heating treatment can be performed at the time of the pressurization treatment. The heating temperature at the time of the heating treatment is not particularly limited, and is preferably 30 to 300°C, and the heating time is preferably 1 minute to 6 hours.

[0320] The atmosphere at the time of the pressurization is not particularly limited, and can be an atmosphere under atmospheric pressure, under dry air (dew point -20°C or lower), and under an inert gas (for example, argon, helium, and nitrogen).

[0321] <Electrode sheet for all-solid-state lithium ion secondary battery>

[0322] The lithium ion conductor of the present application can be contained in an electrode sheet for an all-solid-state lithium ion secondary battery.

[0323] The electrode sheet for an all-solid-state lithium ion secondary battery of the present application is a sheet-shaped molded body capable of forming an electrode active material layer of an all-solid-state lithium ion secondary battery, and is preferably used for an electrode or a laminate of an electrode and a solid electrolyte layer.

[0324] The electrode sheet for an all-solid-state lithium ion secondary battery of the present application (also simply referred to as "electrode sheet") is an electrode sheet having an active material electrode layer (hereinafter, also simply referred to as "active material electrode layer") selected from the group consisting of a negative electrode active material layer and a positive electrode active material layer, and can be a sheet in which the active material electrode layer is formed on a substrate (current collector), or a sheet formed of the active material electrode layer without a substrate. The electrode sheet is generally a sheet having a current collector and an active material electrode layer, but also includes a form having a current collector, an active material electrode layer, and a solid electrolyte layer in this order, and a form having a current collector, an active material electrode layer, a solid electrolyte layer, and an active material electrode layer in this order.

[0325] The electrode sheet of the present application can have the other layers described above. The layer thickness of each layer constituting the electrode sheet of the present application is the same as the layer thickness of each layer described later in the all-solid-state lithium ion secondary battery.

[0326] In the sheet for an all-solid-state lithium ion secondary battery of the present application, at least one layer of the active material electrode layer contains the lithium ion conductor of the present application.

[0327] The method for producing the electrode sheet for an all-solid-state lithium ion secondary battery of the present application is not particularly limited, and for example, can be produced by forming the active material electrode layer using the electrode-forming composition of the present application.

[0328] For example, a method in which the electrode-forming composition is coated on the current collector (may be through other layers) to form a coating film, and the coating film is subjected to a pressurization treatment can be mentioned.

[0329] As the method of coating the electrode-forming composition and the method of subjecting the coating film to a pressurization treatment, the methods described in the electrode-forming composition can be mentioned.

[0330]

[0331] The all-solid-state lithium ion secondary battery of the present application has a positive electrode active material layer, a negative electrode active material layer opposing the positive electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer. The positive electrode active material layer is preferably formed on a positive electrode current collector and constitutes a positive electrode. The negative electrode active material layer is preferably formed on a negative electrode current collector and constitutes a negative electrode.

[0332] At least one of the negative electrode active material layer, the positive electrode active material layer, and the solid electrolyte layer contains the lithium ion conductor of the present application.

[0333] Each of the thicknesses of the negative electrode active material layer, the solid electrolyte layer, and the positive electrode active material layer is not particularly limited. From the viewpoint of the size of a general all-solid-state lithium ion secondary battery, each of the thicknesses of the layers is preferably 10 to 1000 μm, more preferably 20 μm or more and less than 500 μm.

[0334] The thickness of at least one of the positive electrode active material layer and the negative electrode active material layer is further preferably 50 μm or more and less than 500 μm.

[0335] Each of the positive electrode active material layer and the negative electrode active material layer can have a current collector on the side opposite to the solid electrolyte layer.

[0336] The all-solid-state lithium ion secondary battery of the present application can be used as an all-solid-state lithium ion secondary battery in the state of the above structure according to the use, but in order to make it in the form of a dry cell, it is preferably further enclosed in a proper case. The case can be a case made of metal or a case made of resin (plastic). As the case made of metal, for example, an aluminum alloy case and a stainless steel case can be given. The case made of metal is preferably divided into a positive electrode side case and a negative electrode side case and is electrically connected to the positive electrode current collector and the negative electrode current collector, respectively. The case on the positive electrode side and the case on the negative electrode side are preferably joined to be integrated with a spacer for preventing short circuit therebetween.

[0337] Hereinafter, with reference to Figure 9 , the all-solid-state lithium ion secondary battery according to the preferred embodiment of the present application will be described, but the present application is not limited thereto.

[0338] Figure 9 is a cross-sectional view schematically showing the all-solid-state lithium ion secondary battery according to the preferred embodiment of the present application. The all-solid-state lithium ion secondary battery 10 of the present embodiment has, in order from the negative electrode side, a negative electrode current collector 1, a negative electrode active material layer 2, a solid electrolyte layer 3, a positive electrode active material layer 4, and a positive electrode current collector 5.

[0339] ​At least one of the negative electrode active material layer 2, the positive electrode active material layer 4, and the solid electrolyte layer 3 contains the lithium ion conductor of the present application.

[0340] Each layer is in contact with each other in an adjacent structure. By adopting such a structure, electrons (e - ) are supplied to the negative electrode side at the time of charging, and lithium ions (Li + ) are accumulated therein. On the other hand, at the time of discharging, lithium ions (Li + ) accumulated in the negative electrode are returned to the positive electrode side, and electrons are supplied to the working portion 6. In the illustrated example, a light bulb is used as a model in the working portion 6, and the light bulb is made to emit light by discharging.

[0341] The negative electrode active material layer 2 contains the above-described negative electrode active material.

[0342] The positive electrode active material layer 4 contains the above-described positive electrode active material.

[0343] The positive electrode current collector 5 and the negative electrode current collector 1 are preferably electron conductors.

[0344] As a material for forming the positive electrode current collector, aluminum, aluminum alloy, stainless steel, nickel, and titanium can be given, and aluminum or aluminum alloy is preferable. In addition, as the positive electrode current collector, a current collector (a thin film-formed current collector) in which carbon, nickel, titanium, or silver is treated on the surface of aluminum or stainless steel can also be given.

[0345] As a material for forming the negative electrode current collector, aluminum, copper, copper alloy, stainless steel, nickel, and titanium can be given, and aluminum, copper, copper alloy, or stainless steel is preferable. In addition, as the negative electrode current collector, a current collector in which carbon, nickel, titanium, or silver is treated on the surface of aluminum, copper, copper alloy, or stainless steel can also be given.

[0346] The shape of the current collector is usually a thin film sheet shape, but can be other shapes.

[0347] The thickness of the current collector is not particularly limited, and is preferably 1 to 500 μm.

[0348] Further, it is also preferable to provide a concave-convex structure on the surface of the current collector by surface treatment.

[0349] The method for producing the above-described all-solid-state lithium ion secondary battery is not particularly limited, and a publicly known method can be given. Among them, a method using the above-described electrode-forming composition and / or the solid electrolyte layer-forming composition is preferable.

[0350] For example, a positive electrode active material layer is formed by applying a positive electrode formation composition containing a positive electrode active material on a metal foil serving as a positive electrode current collector, followed by applying a solid electrolyte layer formation composition on the positive electrode active material layer to form a solid electrolyte layer, and further applying a negative electrode formation composition containing a negative electrode active material on the solid electrolyte layer to form a negative electrode active material layer, and a negative electrode current collector (metal foil) is laminated on the negative electrode active material layer, and the obtained laminate is further subjected to pressure treatment, whereby a full solid-state lithium ion secondary battery having a structure in which the solid electrolyte layer is interposed between the positive electrode active material layer and the negative electrode active material layer can be obtained. It can also be enclosed in a case to serve as a desired full solid-state lithium ion secondary battery.

[0351] In addition, contrary to the method of forming each layer, a full solid-state lithium ion secondary battery can also be manufactured by forming a negative electrode active material layer, a solid electrolyte layer, and a positive electrode active material layer on a negative electrode current collector and overlapping a positive electrode current collector.

[0352] In addition, as another method, a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer can be separately produced, laminated, and a full solid-state lithium ion secondary battery can be manufactured.

[0353] The full solid-state lithium ion secondary battery is preferably subjected to initialization after production or before use. The initialization is not particularly limited, and for example, initial charging and discharging can be performed in a state in which the pressing pressure is increased, and thereafter, the deintercalation pressure is performed until the general use pressure of the full solid-state lithium ion secondary battery is reached.

[0354] <Usage of the full solid-state lithium ion secondary battery>

[0355] The full solid-state lithium ion secondary battery of the present application can be applied to various uses. The application mode is not particularly limited, and for example, in the case of being mounted on an electronic device, a notebook computer, a pen input computer, a mobile computer, an electronic book reader, a mobile phone, a wireless telephone handset, a pager, a handheld terminal, a portable facsimile machine, a portable copying machine, a portable printer, a stereo headphone, a camcorder, a liquid crystal television, a handheld vacuum cleaner, a portable CD, a small disk, an electric shaver, a transceiver, an electronic diary, a calculator, a memory card, a portable recorder, a radio, and a backup power source can be mentioned. As other civil products, a car, an electric vehicle, a motor, a lighting appliance, a toy, a game machine, a load regulator, a timepiece, a flash, a camera, and a medical instrument (a cardiac pacemaker, a hearing aid, and a shoulder massager, etc.) can be mentioned. In addition, it can be used as various military products and aviation products. Furthermore, it can also be combined with a solar cell.

[0356] Example

[0357] Hereinafter, the present application will be described in further detail according to Examples, but the present application is not limited to the following Examples. In the following Examples, "parts" and "%" indicating the composition are mass-based unless otherwise specified.

[0358] <Production of the 1st lithium compound>

[0359] As the 1st lithium compound, Li2CO3 (99.9%, manufactured by RARE METALLIC Co., Ltd.), La2O3 (96.68%, manufactured by FUJIFILM Wako Pure Chemical Corporation), and ZrO2 (99.9%, manufactured by SHUZUI SCALES CO., LTD.) were used as raw materials, and a LiLaZr oxide (hereinafter: LLZO) having a garnet structure containing Li-La-Zr-O was synthesized by a solid phase method.

[0360] Specifically, the raw material powders were mortar-mixed, placed on an alumina plate, covered with an alumina crucible, fired at 850°C for 12 hours under the atmosphere, and a calcined powder was synthesized. A pressed powder pellet was produced using the synthesized calcined powder. The obtained pressed powder pellet was wrapped in a calcined powder, fired at 1100 to 1230°C for 6 hours under the atmosphere, and the 1st lithium compound was obtained.

[0361] The lithium ion conductivity of the obtained 1st lithium compound at 25°C was 3.7 x 10- 4 S / cm. In addition, regarding the lithium ion conductivity, an Au electrode was provided on the front and back surfaces of the particles of the obtained 1st lithium compound by an evaporation method, and the lithium ion conductivity was estimated by analyzing the arc diameter of a Cole-Cole plot (Nyquist plot) obtained by an alternating current impedance measurement (measurement temperature: 25°C, applied voltage: 100 mV, measurement frequency range: 1 Hz to 1 MHz) via the two Au electrodes.

[0362] Further, the composition of the obtained 1st lithium compound was analyzed by a neutron diffraction method and a rietveld method, and it was confirmed that the composition was Li 5.95 Al 0.35 La3Zr2O 12 .

[0363] Further, the particle size distribution of the obtained 1st lithium compound was about several μm to 10 μm, and the median particle diameter (D50) was 3.1 μm. In addition, the particle size distribution of the 1st lithium compound was obtained by the above-described image analysis method as an input value for fitting when the bulk modulus was obtained later.

[0364] Further, the bulk modulus of the obtained 1st lithium compound was 105 GPa.

[0365] The bulk modulus was calculated by the following method.

[0366] First, the 1st lithium compound was suspended in pure water (concentration: 1.2 mass%), and an ultrasonic attenuation spectrum was measured, and the bulk modulus of the particles was calculated by fitting based on the scattering attenuation theory formula. The fitting was performed with the density of the 1st lithium compound set to 4.97 g / ml and the Poisson's ratio set to 0.257. An ultrasonic attenuation spectrum that monotonously increased from 10 to 70 MHz was obtained from the 1st lithium compound. The measured ultrasonic attenuation spectrum could be well fitted by the scattering attenuation theory with the particle size distribution (approximated by Schultz distribution with an average of 4.7 μm), the density of the particles, and the Poisson's ratio as input values.

[0367] <Production of the 2nd lithium compound>

[0368] A ball mill (P-7 manufactured by Fritsch Japan Co., Ltd.) was used to mill Li2B4O7 (LBO) powder (manufactured by RARE METALLIC Co., Ltd.) under the following conditions: a crucible: YSZ (45 ml), balls for pulverization: YSZ (average particle diameter: 5 mm, number: 50), rotation speed: 500 rpm (revolutions per minute), amount of LBO powder: 2 g, atmosphere: atmosphere, and processing time of the ball mill: 100 hours, to obtain the 2nd lithium compound.

[0369] The particle size distribution of the obtained 2nd lithium compound was about several μm to 10 μm, and the median particle diameter (D50) was 1.5 μm.

[0370] Further, the bulk modulus of the obtained 2nd lithium compound was 36 GPa. In addition, the bulk modulus of the raw material LBO powder before the ball milling process was 47 GPa.

[0371] The calculation method of the median particle diameter and the bulk modulus was the same as that of the median particle diameter and the bulk modulus of the 1st lithium compound. In addition, in the calculation of the bulk modulus, the density of the 2nd lithium compound was 2.3 g / ml, and the Poisson's ratio was set to 0.12 to perform the fitting.

[0372] X-ray total scattering measurement was performed using the obtained 2nd lithium compound at SPring-8 BL04B2 (acceleration voltage: 61.4 keV, wavelength: ). The sample was sealed in a 2 mmφ or 1 mmφ kapton capillary, and the experiment was performed under vacuum. In addition, the obtained data was Fourier transformed as described above to obtain the reduced pair distribution function.

[0373] The results of the analysis were that in the reduced pair distribution function G(r) obtained by the X-ray total scattering measurement, in the range of r exceeding , G(r) showing a peak top was 1.0 or more, the peak top was located at , the 1st peak and G(r) showing a peak top was 1.0 or more, the peak top was located at 2. , the 2nd peak, and it was confirmed that the absolute value of G(r) in the range of r exceeding and was less than 1.0 (refer to Figure 1 ).

[0374] From the results described above Figure 1 , in the 2nd lithium compound, there was almost no long-range order, and it was confirmed to be amorphous. On the other hand, in the 2nd lithium compound, peaks attributed to B-O interdistance and B-B interdistance observed in general lithium tetraborate crystals were maintained. It is presumed that general lithium tetraborate crystals have a structure in which BO3 tetrahedra and BO2 triangles exist at 1:1 (di borate structure), and the structure was maintained in the 2nd lithium compound.

[0375] Further, powder X-ray diffraction of the 2nd lithium compound was performed, and it was confirmed that there was no crystallinity diffraction line in the range of 20 to 25° in 2Θ.

[0376] The solid 7 Li-NMR measurement of the obtained 2nd lithium compound was performed at 20°C, and the half width full width (half width full width 1) of the peak in which the chemical shift appeared in the range of -100 to +100 ppm in the spectrum obtained at the time of the solid 7 Li-NMR measurement of the 2nd lithium compound was performed at 120°C, and the ratio {(half width full width 2 / half width full width 1) x 100} of the half width full width (half width full width 2) of the peak in which the chemical shift appeared in the range of -100 to +100 ppm in the spectrum obtained at the time of the solid

[0377] In the Raman spectrum of the obtained 2nd lithium compound, the determination coefficient obtained by performing linear regression analysis using the least squares method in the wave number range of 600 to 850 cm -1 was 0.9677.

[0378] (Comparative LBO powder)

[0379] As the comparative LBO powder described later, a (LBO) powder (manufactured by RARE METALLIC Co., Ltd.) on which ball milling treatment was not performed was used.

[0380] Using the comparative LBO powder, the results of the X-ray total scattering measurement were the same as those of the 2nd lithium compound described above, in the reduced pair distribution function G(r), in the range of r exceeding and The following range has a peak of G(r) of 1.0 or more, and does not satisfy the requirement 1.

[0381] Further, the proportion of the peak having a chemical shift in the range of -100 to +100 ppm in the spectrum obtained at the time of Li-NMR measurement (half-peak full width 2) {(half-peak full width 2 / half-peak full width 1) x 100} was 99.6%. 7 The following range has a peak of G(r) of 1.0 or more, and does not satisfy the requirement 1. 7 The following range has a peak of G(r) of 1.0 or more, and does not satisfy the requirement 1.

[0382] In the Raman spectrum of the comparative example LBO powder, the correlation coefficient obtained by performing linear regression analysis using the least square method in the wave number range of 600 to 850 cm -1 was 0.1660.

[0383] <Example 1>

[0384] The composite was obtained by mixing the above-obtained first lithium compound and second lithium compound at a mixing mass ratio of 8:1 (mass of the first lithium compound : mass of the second lithium compound).

[0385] Next, the obtained composite was subjected to a powder compression molding at a practical pressure of 100 MPa at 25°C (room temperature), and a powder (lithium ion conductor) was obtained.

[0386] The lithium ion conductivity of the obtained powder was 1.3 x 10 -6 S / cm.

[0387] It was found that the adhesion of the interface of the first lithium compound / second lithium compound was good by observing the obtained powder by a scanning electron microscope (observation accelerating voltage: 3 kV, EDX: 30 kV).

[0388] <Example 2>

[0389] The mixing mass ratio of the first lithium compound and the second lithium compound (mass of the first lithium compound : mass of the second lithium compound) was changed from 8:1 to 4:1, and otherwise, a powder (lithium ion conductor) was obtained according to the same procedure as in Example 1.

[0390] The lithium ion conductivity of the obtained powder was 1.2 x 10 -5 S / cm.

[0391] <Example 3>

[0392] The mixed mass ratio (mass of the first lithium compound : mass of the second lithium compound) of the first lithium compound and the second lithium compound was changed from 8:1 to 2:1, and a powder compact (lithium ion conductor) was obtained according to the same procedure as in Example 1, except for this.

[0393] The lithium ion conductivity of the obtained powder compact was 4.3 x 10 -6 S / cm.

[0394] Example 4

[0395] The mixed mass ratio (mass of the first lithium compound : mass of the second lithium compound) of the first lithium compound and the second lithium compound was changed from 8:1 to 1:1, and a powder compact (lithium ion conductor) was obtained according to the same procedure as in Example 1, except for this.

[0396] The lithium ion conductivity of the obtained powder compact was 3.0 x 10 -6 S / cm.

[0397] Comparative Example 1

[0398] A comparative example LBO powder was used instead of the second lithium compound, and a powder compact (lithium ion conductor) was obtained according to the same procedure as in Example 2, except for this.

[0399] The lithium ion conductivity of the obtained powder compact was 10 -8 S / cm.

[0400] It was found that, by observing the obtained powder compact by scanning electron microscopy (observation accelerating voltage: 3 kV, EDX: 30 kV), there were voids at the interface of the first lithium compound / comparative example LBO powder.

[0401] Evaluation

[0402] (Raman spectrum)

[0403] Raman spectrum measurement was performed on the powder compacts obtained in Examples 1 to 4 and Comparative Example 1.

[0404] In the powder compacts of Examples 1 to 4, characteristic Raman bands (strong bands present in the ranges of 716 to 726 cm -1 , 771 to 785 cm -1 , and 1024 to 1034 cm -1 ) were hardly confirmed in the LBO crystal, whereas in the powder compact of Comparative Example 1, characteristic Raman bands were confirmed in the LBO crystal.

[0405] Next, Raman imaging measurement was performed on the green compact obtained in each of Examples 1 to 4 and Comparative Example 1. As the measurement conditions, the excitation light was set to 532 nm, the objective lens was set to 100 times, the mapping method was point scanning, the step size was 1 μm, the exposure time per 1 point was set to 1 second, the number of accumulations was set to 1, and the measurement range was set to a range of 70 μm x 50 μm. The noise of the obtained data was removed by PCA processing.

[0406] According to the above procedure, the region derived from the first lithium compound and the region derived from the second lithium compound were specified in each of the green compacts of Examples 1 to 4. Also, the region derived from the first lithium compound and the region derived from the Comparative Example LBO powder were specified in Comparative Example 1.

[0407] Next, the ratio of the Raman intensity of the Raman spectrum of the second lithium compound in the green compacts of Examples 1 to 4 at 1800 cm -1 to the Raman intensity at 1000 cm -1 (1800 cm -1 intensity / 1000 cm -1 intensity) was calculated. The results are shown in Table 1.

[0408] Also, the determination coefficient obtained by linear regression analysis using the least squares method in the wave number range of 600 to 850 cm -1 of the Raman spectrum of the second lithium compound in the green compacts of Examples 1 to 4 was calculated. With respect to the green compact of Comparative Example 1, the determination coefficient in the above prescribed frequency range was calculated using the Raman spectrum of the Comparative Example LBO powder. The results are shown in Table 1.

[0409] In Table 1, in the column of "Requirement 1", "A" indicates that the above requirement 1 is satisfied, and "B" indicates that the above requirement 1 is not satisfied.

[0410] In Table 1, in the column of "Full Width at Half Maximum Ratio (%)", the full width at half maximum of the peak in which the chemical shift appeared in the range of -100 to +100 ppm in the spectrum obtained at the time of the solid 7 Li-NMR measurement of the second lithium compound (or, the Comparative Example LBO powder) at 20°C is shown. 7 In Table 1, in the column of "Full Width at Half Maximum Ratio (%)", the full width at half maximum of the peak in which the chemical shift appeared in the range of -100 to +100 ppm in the spectrum obtained at the time of the solid -1 Li-NMR measurement of the second lithium compound (or, the Comparative Example LBO powder) at 20°C is shown.

[0411] In Table 1, in the column of "Determination Coefficient" of "Second Lithium Compound" and "Comparative Example LBO Powder", the determination coefficient obtained by linear regression analysis using the least squares method in the wave number range of 600 to 850 cm -1a coefficient of determination obtained by linear regression analysis by least square method in a frequency region of 600 to 850 cm

[0412] In the column of "mixing ratio" in Table 1, a mixing mass ratio (mass of the 1st lithium compound : mass of the 2nd lithium compound) is shown.

[0413] In the column of "intensity ratio" in Table 1, a ratio of a Raman intensity of the Raman spectrum of the 2nd lithium compound at 1800 cm -1 to a Raman intensity at 1000 cm -1 is shown.

[0414] In the column of "coefficient of determination" of "lithium ion conductor" in Table 1, a coefficient of determination obtained by linear regression analysis by least square method in a frequency region of 600 to 850 cm -1 of the Raman spectrum of the 2nd lithium compound in the lithium ion conductor (or LBO powder in the comparative example) is shown.

[0415]

[0416] As shown in Table 1, by using the composite of the present application, a desired lithium ion conductor was obtained.

[0417] Explanation of symbols

[0418] 1 - negative electrode current collector, 2 - negative electrode active material layer, 3 - solid electrolyte layer, 4 - positive electrode active material layer, 5 - positive electrode current collector, 6 - working part, 10 - all-solid-state lithium ion secondary battery.

Claims

1. A composite material for a solid electrolyte in an all-solid-state lithium-ion secondary battery, comprising: The lithium-ion conductivity at 25℃ is 1.0 × 10⁻⁶. -6 First lithium compounds with a S / cm or higher; and Lithium tetraborate that meets the following requirement 1 Requirement 1: In the reduced pair distribution function G(r) obtained by X-ray total scattering measurement of the lithium tetraborate, there exists a peak located at r. The first peak and its summit are located at r. The second peak in the range, the G(r) at the peak of the first peak and the G(r) at the peak of the second peak both show values ​​exceeding 1.0, and r exceeds... and Within the following range, the absolute value of G(r) is less than 1.

0. The content of the first lithium compound in the composite is 50-97% by mass relative to the total mass of the composite. The bulk modulus of the first lithium compound is 50–300 GPa.

2. The solid electrolyte composite for an all-solid-state lithium-ion secondary battery according to claim 1, wherein, Compared to the solid lithium tetraborate produced at 20°C 7 The frequency shift in the spectrum obtained during Li-NMR determination appears in the full width at half maximum (FWHM) of the peaks in the range of -100 to +100 ppm. This was achieved by solid-state analysis of the lithium tetraborate at 120 °C. 7 In Li-NMR measurements, the frequency shifts in the spectrum obtained occur in peaks within the range of -100 to +100 ppm, and the proportion of the full width at half maximum (FWHM) of these peaks is less than 70%.

3. The solid electrolyte composite for an all-solid-state lithium-ion secondary battery according to claim 1 or 2, wherein, The bulk modulus of the lithium tetraborate is below 45 GPa.

4. The solid electrolyte composite for an all-solid-state lithium-ion secondary battery according to claim 1 or 2, wherein, The first lithium compound is a lithium oxide.

5. The solid electrolyte composite for an all-solid-state lithium-ion secondary battery according to claim 1 or 2, wherein, The first lithium compound includes at least one selected from the group consisting of: Lithium compounds containing at least Li, La, Zr and O that have a garnet-type or garnet-like structure; Lithium compounds with a perovskite-type structure that contain at least Li, Ti, La and O; It contains at least Li and M 1 P and O and the M mentioned above 1 Lithium compounds containing at least one of Ti, Zr, and Ge having a NASICON-type structure; Lithium compounds containing at least Li, P, O and N with an amorphous structure; Lithium compounds with a monoclinic crystal structure containing at least Li, Si and O; By LiM 2 X 1 O4 represents a lithium compound with an olivine-type structure, wherein M 2 Represents a divalent or trivalent element, when M 2 When representing a divalent element, X 1 Represents a pentavalent element, when M 2 When representing a trivalent element, X 1 Indicates a tetravalent element; It contains at least Li, O and X 2 Lithium compounds having an anti-perovskite structure, wherein the X 2 It represents at least one of Cl, Br, N, and I; By Li2M 3 Y4 represents a lithium compound with a spinel-type structure, wherein M 3 Y represents at least one of Cd, Mg, Mn, and V; and Y represents at least one of F, Cl, Br, and I. Lithium compounds with a β-alumina structure.

6. A lithium-ion conductor for a solid electrolyte in an all-solid-state lithium-ion secondary battery, which is formed using a composite for a solid electrolyte in an all-solid-state lithium-ion secondary battery according to any one of claims 1 to 5.

7. The lithium-ion conductor for the solid electrolyte of the all-solid-state lithium-ion secondary battery according to claim 6, wherein it satisfies requirement 2 or requirement 3. Requirement 2: The Raman spectrum of the lithium tetraborate in the lithium-ion conductor is within 1800 cm⁻¹. -1 The Raman intensity at 1000 cm⁻¹ is -1 More than 1.60 times the Raman intensity of the previous one. Requirement 3: The Raman spectrum of the lithium tetraborate in the lithium-ion conductor at 600–850 cm⁻¹ -1 The coefficient of determination obtained by linear regression analysis using the least squares method within the wavenumber range is above 0.8900.

8. A fully solid-state lithium-ion secondary battery, comprising sequentially a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer, wherein, At least one of the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer comprises a lithium-ion conductor for a solid electrolyte in the all-solid-state lithium-ion secondary battery according to claim 6 or 7.

9. An electrode sheet for an all-solid-state lithium-ion secondary battery, comprising a lithium-ion conductor for a solid electrolyte of the all-solid-state lithium-ion secondary battery as described in claim 6 or 7.

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