Mixture for all-solid-state lithium-ion batteries, positive electrode active material layer for all-solid-state lithium-ion batteries, all-solid-state lithium-ion batteries, mobile devices and batteries for driving mobile devices.

Abstract

To provide a mixture for an all-solid lithium ion battery, which enables an increase in the discharge capacity of an all-solid lithium ion battery, and which is superior in charge / discharge cycle characteristic under a high-temperature and high-voltage condition, a positive electrode active material layer for an all-solid lithium ion battery, an all-solid lithium ion battery, a movable body, and a movable body-driving battery.SOLUTION: A mixture for an all-solid lithium ion battery comprises a lithium metal composite oxide and a LGPS-based sulfide solid electrolyte. The lithium metal composite oxide has a layered structure, and contains at least Li, Mn, and an element M1, and satisfies the following composition formula (1): aLi2MnO3 (1-a)LiM1O2 (1). The LGPS-based sulfide solid electrolyte contains an element M2, an element M3, and S. The LGPS-based sulfide solid electrolyte satisfies the requirements (A) and (B) in a diffraction pattern gained as a result of measurement by an X-ray diffraction method with Cu Kα rays.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a mixture for all-solid-state lithium-ion batteries, a positive electrode active material layer for all-solid-state lithium-ion batteries, an all-solid-state lithium-ion battery, a mobile device, and a battery for driving a mobile device. [Background technology]

[0002] Lithium-ion batteries include liquid-based lithium-ion batteries, which use an electrolyte containing an organic solvent, and all-solid-state lithium-ion batteries, which use a solid electrolyte. All-solid-state lithium-ion batteries have the advantage of being safer to use than liquid-based lithium-ion batteries, with a lower risk of leakage, ignition, or explosion, and development is progressing because they may be usable in high-temperature or low-temperature environments where liquid-based lithium-ion batteries are difficult to use.

[0003] All-solid-state lithium-ion batteries, which offer easier safety assurance, are being considered for use in automobiles, aircraft, and other applications. When used in automobiles and aircraft, all-solid-state lithium-ion batteries require increased capacity, for example, to extend air travel distances.

[0004] As an attempt to improve the capacity of lithium-ion batteries, Patent Document 1 discloses a lithium composite metal oxide that can be used as a lithium-rich positive electrode active material. The lithium-rich positive electrode active material is a positive electrode active material that has both a hexagonal crystal structure and a monoclinic crystal structure, and a high discharge capacity can be obtained by high-voltage charging at 4.5V. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2008-98154 [Overview of the project] [Problems that the invention aims to solve]

[0006] In addition to increased capacity, all-solid-state lithium-ion batteries require durability at high temperatures. Especially when using high-capacity positive electrode active materials, particle expansion and contraction during the charge-discharge process become significant. Therefore, it is necessary to suppress interfacial delamination between the positive electrode active material and the solid electrolyte, and to maintain high ionic conductivity between the positive electrode active material and the solid electrolyte even under high temperatures and high voltages, thereby improving charge-discharge cycle characteristics.

[0007] The present invention has been made in view of these circumstances, and aims to provide a mixture for all-solid-state lithium-ion batteries, a positive electrode active material layer for all-solid-state lithium-ion batteries, an all-solid-state lithium-ion battery, a mobile device, and a battery for driving a mobile device that increase the discharge capacity of all-solid-state lithium-ion batteries and further exhibit excellent charge-discharge cycle characteristics under high temperature and high voltage conditions.

[0008] In this specification, "excellent charge-discharge cycle characteristics under high temperature and high voltage conditions" is evaluated by conducting a charge-discharge cycle test under conditions of 60°C and a maximum charging voltage of 4.0V. [Means for solving the problem]

[0009] One aspect of the present invention encompasses [1] to

[16] . [1] A mixture for an all-solid-state lithium-ion battery comprising a lithium metal composite oxide and an LGPS-based sulfide solid electrolyte, wherein the lithium metal composite oxide has a layered structure, contains at least Li, Mn and element M1, and satisfies the following composition formula (1), the LGPS-based sulfide solid electrolyte contains elements M2, M3 and S, element M2 is at least one selected from the group consisting of Li, Na, K, Mg, Ca, and Zn, element M3 is at least one selected from the group consisting of P, Sb, Si, Ge, Sn, B, Al, Ga, In, Ti, Zr, V, and Nb, and the LGPS-based sulfide solid electrolyte satisfies the following (A) and (B) in the diffraction pattern obtained by measurement using an X-ray diffraction method with CuKα rays, the mixture for an all-solid-state lithium-ion battery. aLi2MnO3·(1-a)LiM1O2···(1) (0.1 < a < 1, element M1 is one or more elements selected from the group consisting of Ni, Co, Mn, Fe, Cu, Ti, Na, Mg, Ca, Sr, Ba, B, Al, Si, P, W, Mo, Nb, Zn, Sn, Zr, Cr, Ga, Ge, Pd, Ag, Cd, In and V) (A) It has peaks at positions of 2θ = 20.18° ± 0.50°, 2θ = 20.44° ± 0.50°, 2θ = 26.96° ± 0.50°, and 2θ = 29.58° ± 0.50°. (B) I B / I A < 0.50 (I A is the diffraction intensity of the peak at the position of 2θ = 29.58° ± 0.50°, and I B is the diffraction intensity of the peak at the position of 2θ = 27.33° ± 0.50°.) [2] The mixture for an all-solid-state lithium ion battery according to [1], wherein the LGPS-based sulfide solid electrolyte satisfies the following (B)-1. (B)-1 I B / I A ≦ 0.25 [3] The mixture for an all-solid-state lithium ion battery according to [1] or [2], wherein the LGPS-based sulfide solid electrolyte has peaks at positions of 2θ = 17.38 ± 0.50°, 2θ = 23.56 ± 0.50°, 2θ = 23.96 ± 0.50°, 2θ = 24.93 ± 0.50°, 2θ = 29.07 ± 0.50°, 2θ = 31.71 ± 0.50°, 2θ = 32.66 ± 0.50°, and 2θ = 33.39 ± 0.50° in a diffraction pattern obtained by measurement using an X-ray diffraction method with CuKα radiation. [4] The mixture for an all-solid-state lithium ion battery according to any one of [1] to [3], wherein the element M2 is Li and the elements M3 are Ge and P. [5] The composition of the LGPS-based sulfide solid electrolyte is Li (4-x) Ge (1-x) P x S4 (where x satisfies 0 < x < 1), the mixture for an all-solid-state lithium ion battery according to [4]. [6] The mixture for all-solid-state lithium-ion batteries described in [5], wherein x satisfies 0.5 ≤ x ≤ 0.8. [7] The lithium metal composite oxide is a mixture for all-solid-state lithium-ion batteries according to any one of [1] to [6] that satisfies (3) below. 0.01≦I 020 / I 003 ≤0.3 ···(3) [I 020 This is the integrated intensity of the peak of the (020) plane, which is attributed to the crystal structure of space group C2 / m, in the X-ray diffraction pattern of the lithium metal composite oxide using CuKα rays. I 003 This represents the integrated intensity of the peak of the (003) plane, which is attributed to the crystal structure of space group R-3m. [8] The lithium metal composite oxide has a specific surface area of ​​0.3 m². 2 / g or more 2.0m 2 A mixture for all-solid-state lithium-ion batteries described in any one of [1] to [7] that satisfies less than or equal to / g. [9] The mixture for an all-solid-state lithium-ion battery according to any one of [1] to [8], wherein the mass ratio of the lithium metal composite oxide to the LGPS-based sulfide solid electrolyte is 60:40 to 95:5. A positive electrode active material layer for an all-solid-state lithium-ion battery comprising the mixture for all-solid-state lithium-ion batteries described in any one of

[10] [1] to [9].

[11] A positive electrode active material layer for an all-solid-state lithium-ion battery according to

[10] , further comprising a conductive material. An all-solid-state lithium-ion battery comprising a positive electrode containing a positive electrode active material layer for all-solid-state lithium-ion batteries as described in

[12]

[10] or

[11] , a negative electrode, and a solid electrolyte layer containing a sulfide-based compound sandwiched between the positive electrode and the negative electrode. A mobile device equipped with the all-solid-state lithium-ion battery described in

[13]

[12] , and powered by the all-solid-state lithium-ion battery.

[14] An airplane, the mobile entity described in

[13] . A mobile power battery comprising an all-solid-state lithium-ion battery as described in

[15]

[12] and an insulating sheet covering the all-solid-state lithium-ion battery, wherein the thermal conductivity of the insulating sheet is 1 mW / mK or more and 100 mW / mK or less.

[16] A mobile power battery as described in

[15] , for powering an airplane. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a mixture for all-solid-state lithium-ion batteries, a positive electrode active material layer for all-solid-state lithium-ion batteries, an all-solid-state lithium-ion battery, a mobile device, and a battery for driving a mobile device, which have an increased discharge capacity and excellent charge-discharge cycle characteristics under high temperature and high voltage conditions. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram showing the layered structure of an all-solid-state lithium-ion battery. [Figure 2] This is a schematic diagram showing an example of an all-solid-state lithium-ion battery. [Modes for carrying out the invention]

[0012] <Mixture for all-solid-state lithium-ion batteries> This embodiment is a mixture for an all-solid-state lithium-ion battery, comprising a lithium metal composite oxide and an LGPS-based sulfide solid electrolyte. In one embodiment of the present invention, the mixture for the all-solid-state lithium-ion battery is a mixed powder. Hereafter, the mixture for all-solid-state lithium-ion batteries may be abbreviated as "mixture". In the following, unless otherwise specified, the notation "Li" refers to the element Li, not the metallic Li. The same applies to the notation of other elements such as Ni, Co, and Mn.

[0013] Lithium metal composite oxide The lithium metal composite oxide has a layered structure, and contains at least Li and a transition metal element.

[0014] The lithium metal composite oxide contains at least Li, Mn and an element M1 as transition metal elements. When the lithium metal composite oxide contains the above elements as transition metal elements, the obtained lithium metal composite oxide forms a stable crystal structure that allows Li ions to be desorbed or intercalated.

[0015] The lithium metal composite oxide satisfies the following compositional formula (1). aLi2MnO3·(1-a)LiM1O2···(1) (0.1 < a < 1, the element M1 is one or more elements selected from the group consisting of Ni, Co, Mn, Fe, Cu, Ti, Na, Mg, Ca, Sr, Ba, B, Al, Si, P, W, Mo, Nb, Zn, Sn, Zr, Cr, Ga, Ge, Pd, Ag, Cd, In and V.)

[0016] From the viewpoint of enhancing the effect of the present invention, a in the compositional formula (1) is preferably 0.25 or more, more preferably 0.35 or more, and still more preferably 0.45 or more. Further, a in the compositional formula (1) is preferably 0.90 or less, more preferably 0.80 or less, and still more preferably 0.75 or less. The above upper limit values and lower limit values can be arbitrarily combined. As an example of the combination, a is preferably 0.25 or more and 0.90 or less, more preferably 0.35 or more and 0.80 or less, and still more preferably 0.45 or more and 0.75 or less.

[0017] From the viewpoint of obtaining an all-solid-state lithium-ion battery with low internal resistance, it is preferable that element M1 contains Ni. The percentage of Ni contained in element M1 is preferably 20 mol% or more, more preferably 25 mol% or more, and even more preferably 30 mol% or more. It is also preferably 90 mol% or less, more preferably 80 mol% or less, and even more preferably 70 mol% or less. The above upper and lower limits can be combined arbitrarily. As an example of a combination, the percentage of Ni contained in element M1 is preferably 20 mol% or more and 90 mol% or less, more preferably 25 mol% or more and 80 mol% or less, and even more preferably 30 mol% or more and 70 mol% or less.

[0018] As element M1 in composition formula (I), from the viewpoint of improving the stability of the crystal structure during the insertion and removal of lithium ions accompanying the charge-discharge reaction and suppressing the increase in internal resistance after the charge-discharge cycle test, one or more elements selected from the group consisting of Ni, Co, Mn, Fe, Ti, Al, P, W, Mo, Nb, and Zr are preferred.

[0019] [Separation method] To measure the various physical properties of the lithium metal composite oxide and LGPS-based sulfide solid electrolyte contained in the mixture, the lithium metal composite oxide and the LGPS-based sulfide solid electrolyte are separated from the mixture. Specifically, the lithium metal composite oxide and the LGPS-based sulfide solid electrolyte can be separated from the mixture by centrifuging the mixture using a powder separator. The centrifugal conditions for separation are set by appropriately adjusting the rotation speed and residence time of the centrifuge.

[0020] [Compositional analysis of lithium metal composite oxides] For compositional analysis of lithium metal composite oxides, the lithium metal composite oxides separated from the mixture by the method described in [Separation Method] above are dissolved in hydrochloric acid, and then their composition is analyzed using an inductively coupled plasma emission spectrometer (for example, SPS3000, manufactured by SII Nanotechnology Co., Ltd.).

[0021] When the measured lithium metal composite oxide is represented by compositional formula (1), it can be calculated from the results of the above compositional analysis using the following method.

[0022] First, in the empirical formula (1), a is the amount of Li (M) determined by compositional analysis. Li =2×a+(1-a)=1+a), and the total amount of substance of Mn and element M1 (M Mn+M1 Using =a+(1-a)=1), M Li :(M Mn+M1 The ratio is calculated using the relationship ) = (1+a):1. Lithium metal composite oxide contains Li2MnO3 in proportion a and LiM1O2 in proportion (1-a) in compositional formula (1). Therefore, lithium metal composite oxide contains element M1 in proportion (1-a) in compositional formula (1).

[0023] For example, if a lithium metal composite oxide contains Mn and Ni as element M1, the amount of Mn in Li2MnO3 corresponds to the ratio of 'a' to the total amount of Mn and element M1, out of the amount of Mn (total amount of Mn) calculated from the above compositional analysis, and the remainder is the amount of Mn contained in element M1 (A). Mn )

[0024] From the value of a calculated using the above method, the amount of substance of Mn contained in element M1 (A Mn ) is calculated, and the amount of substance of Mn contained in element M1 (A Mn ), the amount of Ni calculated from the above compositional analysis (A Ni ), and the total amount of substance of element M1 (excluding Ni and Mn) calculated from the results of the above compositional analysis (A x From this, the percentage of Ni (mol%) contained in M1 is calculated using the following formula. Ni content (mol%) in M1 = A Ni / ( A Mn +A Ni +A x )×100 (formula) (Total amount of substance of M1 = A Mn +A Ni +A x )

[0025] In the example above, we assumed that element M1 includes Mn and Ni, but the same calculation can be performed even if element M1 includes other elements.

[0026] [Crystal structure of lithium metal composite oxides] The crystalline structure of lithium metal composite oxides is layered. Lithium metal composite oxides satisfying compositional formula (1) have hexagonal and monoclinic crystalline structures.

[0027] The hexagonal crystal structure is P3, P31, P32, R3, P-3, R-3, P312, P321, P3112, P3121, P3212, P3221, R32, P3m1, P 31m, P3c1, P31c, R3m, R3c, P-31m, P-31c, P-3m1, P-3c1, R-3m, R-3c, P6, P61, P65, P62, P64, P63 It belongs to one of the space groups selected from the group consisting of P-6, P6 / m, P63 / m, P622, P6122, P6522, P6222, P6422, P6322, P6mm, P6cc, P63cm, P63mc, P-6m2, P-6c2, P-62m, P-62c, P6 / mmm, P6 / mcc, P63 / mcm, and P63 / mmc.

[0028] Furthermore, monoclinic crystal structures belong to one of the space groups selected from the group consisting of P2, P21, C2, Pm, Pc, Cm, Cc, P2 / m, P21 / m, C2 / m, P2 / c, P21 / c, and C2 / c.

[0029] Of these, in order to obtain an all-solid-state lithium-ion battery with high discharge capacity, the crystal structure is particularly preferably a hexagonal crystal structure belonging to the space group R-3m, and a monoclinic crystal structure belonging to C2 / m.

[0030] The presence of these crystal structures can be confirmed by X-ray diffraction measurements. The crystal structure of the lithium metal composite oxide can be confirmed by measuring the lithium metal composite oxide separated from the mixture by the method described in [Separation Method] above using an X-ray diffraction measuring device.

[0031] The crystal structure of space group C2 / m belongs to compounds that contain Li in the transition metal layer and is also called the lithium-rich phase. Using lithium metal composite oxides with a lithium-rich phase as the positive electrode active material can increase the discharge capacity of all-solid-state lithium-ion batteries.

[0032] Lithium metal composite oxides are preferably those that satisfy the following (3). 0.01≦I 020 / I 003 ≤0.3 ···(3) [I 020 This is the integrated intensity of the peak of the (020) plane, which is attributed to the crystal structure of space group C2 / m, in the X-ray diffraction pattern of lithium metal composite oxide using CuKα rays. 003 This represents the integrated intensity of the peak of the (003) plane, which is attributed to the crystal structure of space group R-3m.

[0033] I 020 / I 003 Lithium metal composite oxides that satisfy (3) are lithium-rich lithium metal composite oxides that contain a good balance of crystal structures with space group C2 / m and space group R-3m. Therefore, the discharge capacity of all-solid-state lithium-ion batteries using these as positive electrode active materials will be high.

[0034] (3) is preferably (3)-1 or (3)-2 below. (3)-1:0.02≦I 020 / I 003 ≤0.25 (3)-2:0.05≦I 020 / I 003 ≤0.20

[0035] X-ray diffraction measurements are performed using the method described in [X-ray Diffraction Measurement Method] below. The peak of the (003) plane, which belongs to the crystal structure of space group R-3m, appears at 2θ = 18~19°. The peak of the (020) plane, which belongs to the crystal structure of space group C2 / m, appears at 2θ = 21~22°.

[0036] [X-ray diffraction measurement method for lithium metal composite oxides] X-ray diffraction of lithium metal composite oxides is measured using an X-ray diffractometer. Measurements are performed at 25°C. For example, a Rigaku SmartLab X-ray diffractometer can be used.

[0037] The obtained X-ray diffraction pattern is then subjected to peak searching using X-ray analysis software to obtain the diffraction pattern. For example, Rigaku's integrated powder X-ray analysis software PDXL2 can be used as X-ray analysis software.

[0038] From the obtained diffraction pattern, the integral intensity of the peak of the (003) plane that belongs to the crystal structure of space group R-3m (I 003 ) and the integral intensity of the peak of the (020) plane that is attributed to the crystal structure of space group C2 / m (I 020 ) find the ratio (I 020 / I 003 Calculate ).

[0039] Lithium metal composite oxide has a specific surface area of ​​0.3 m². 2 / g or more 2.0m 2 It is preferable that the value be less than or equal to / g, and 0.5m 2 / g or more 1.8m 2 It is more preferable that the condition be less than or equal to / g. If the specific surface area of ​​the lithium metal composite oxide is above the lower limit, a high discharge capacity is more likely to be obtained. If the specific surface area of ​​the lithium metal composite oxide is below the upper limit, it is easier to achieve good cycle characteristics.

[0040] [Method for measuring the specific surface area of ​​lithium metal composite oxides] The specific surface area of ​​lithium metal composite oxide is measured by the following method. The specific surface area of ​​the lithium metal composite oxide separated from the mixture by the method described in [Separation Method] above can be determined by measuring it using a specific surface area measuring device.

[0041] The separated lithium metal composite oxide is measured using a specific surface area analyzer and the nitrogen adsorption BET (Brunauer, Emmett, Teller) method. For example, a specific surface area analyzer manufactured by Mountec (device name: HM model-1208) can be used. Degassing during measurement is performed at 200°C for 20 minutes.

[0042] The lithium metal composite oxide of this embodiment has a 50% cumulative volume particle size D 50 It is preferable that the thickness is between 1 μm and 20 μm. 50 The particle size is more preferably 2 μm or larger, and even more preferably 3 μm or larger. Also, D 50 The particle size is more preferably 15 μm or less, and even more preferably 10 μm or less.

[0043] The above upper and lower limits can be combined in any way. In this embodiment, in particular, the lithium metal composite oxide D 50 However, it is preferable that the particle size is between 2 μm and 15 μm. 50 By setting the range to the above range, the packing density of lithium metal composite oxide in the positive electrode active material layer can be increased.

[0044] [D of lithium metal composite oxides] 50 [Measurement Method] The cumulative volume particle size of the lithium metal composite oxide is measured by laser diffraction scattering. First, 0.1 g of the lithium metal composite oxide separated from the mixture by the method described in [Separation Method] above is added to 50 ml of a 0.2 mass% sodium hexametaphosphate aqueous solution to obtain a dispersion of the powder.

[0045] Next, the particle size distribution of the obtained dispersion is measured using a Microtrac MT3300EXII (laser diffraction scattering particle size distribution analyzer) manufactured by Microtrac-Bell Corporation, and a volume-based cumulative particle size distribution curve is obtained.

[0046] Then, in the obtained cumulative particle size distribution curve, when the total is set to 100%, the particle diameter value at the point where the cumulative volume from the fine particle side reaches 50% is the 50% cumulative volume particle size D. 50 It is (μm).

[0047] [Coating layer] It is preferable to form a coating layer made of a metal composite oxide having lithium ion conductivity on the surface of the lithium metal composite oxide particles. By forming such a coating layer on the surface of the lithium metal composite oxide particles, the decomposition reaction of the LGPS-based sulfide solid electrolyte that occurs between the lithium metal composite oxide and the LGPS-based sulfide solid electrolyte is suppressed. In addition, the transfer of lithium ions by the lithium metal composite oxide is not hindered by the coating layer, and the charge and discharge efficiency of the all-solid-state lithium-ion battery is increased.

[0048] The thickness of the coating layer should be adjusted within a range that does not impair the effects of the present invention. Specifically, a thickness of approximately 1 nm to 20 nm is preferable.

[0049] The thickness of the coating layer is determined by analysis using a scanning transmission electron microscope (STEM) and energy dispersive X-ray spectroscopy (EDX). A line profile of elements specific to the coating layer is created, and based on the obtained line profile, the range in which these specific elements are detected is defined as the range in which the coating layer exists, and the thickness of the coating layer can be determined.

[0050] Examples of such metal composite oxides include metal composite oxides of Li and at least one element selected from the group consisting of Nb, Si, P, Al, W, Ta, Ti, Zr, Mo, and B.

[0051] Methods for forming the coating layer include, for example, spraying a solution containing the elements to be included in the coating layer onto a lithium metal composite oxide and then heat-treating it, or immersing a lithium metal composite oxide in a solution containing the elements to be included in the coating layer and then heat-treating it.

[0052] ≪LGPS-based sulfide solid electrolyte≫ The mixture contains an LGPS-based sulfide solid electrolyte. Using an LGPS-based sulfide solid electrolyte improves the capacity of all-solid-state lithium-ion batteries.

[0053] LGPS-based sulfide solid electrolytes satisfy the following conditions (A) and (B) in the diffraction pattern obtained by measurement using CuKα-based X-ray diffraction.

[0054] (A) Peaks are found at the following positions: 2θ = 20.18° ± 0.50°, 2θ = 20.44° ± 0.50°, 2θ = 26.96° ± 0.50°, and 2θ = 29.58° ± 0.50°.

[0055] (B) I B / I A <0.50 (I A This is the diffraction intensity of the peak at the position 2θ = 29.58° ± 0.50°, and I B This represents the diffraction intensity of the peak at the position 2θ = 27.33° ± 0.50°.

[0056] The LGPS-based sulfide solid electrolyte used in this embodiment has two crystalline phases, crystalline phase A and crystalline phase B, both of which exhibit ionic conductivity. Crystalline phase A and crystalline phase B differ in their ionic conductivity, with crystalline phase A having significantly higher ionic conductivity than crystalline phase B.

[0057] Crystalline phase A has peaks at the positions described in (A) above. In addition to the peaks described in (A) above, peaks may also be present at the following positions: 2θ=17.38±0.50°, 2θ=23.56±0.50°, 2θ=23.96±0.50°, 2θ=24.93±0.50°, 2θ=29.07±0.50°, 2θ=31.71±0.50°, 2θ=32.66±0.50°, and 2θ=33.39±0.50°.

[0058] In this embodiment, the LGPS-based sulfide solid electrolyte exhibits a characteristic peak in crystalline phase A that appears approximately at 2θ = 29.58° ± 0.50°; therefore, this peak is adopted in (B).

[0059] In (B), the diffraction intensity of the peak around 2θ = 29.58° is I A Let the diffraction intensity of the peak around 2θ = 27.33° be I B To, I B / I A The value is specified to be less than 0.50. From the viewpoint of ionic conductivity, it is preferable that the LGPS-based sulfide solid electrolyte has a high proportion of crystalline phase A, which has high ionic conductivity. For this reason, (B) is preferably one of the following (B)-0 to (B)-2.

[0060] (B)-0:I B / I A <0.45 (B)-1:I B / I A ≤0.25 (B)-2:I B / I A ≤0.20

[0061] Also, I B / I A The value of is preferably 0. In other words, it is preferable that the LGPS-based sulfide solid electrolyte does not have a peak around 2θ = 27.33°, which is the peak of crystalline phase B.

[0062] In all-solid-state lithium-ion batteries, lithium ions move within the positive electrode active material layer during charging and discharging. Within this layer, the solid electrolyte serves as the pathway for lithium ion movement. The solid electrolyte is evenly distributed three-dimensionally within the positive electrode active material layer. Therefore, during charging and discharging, lithium ions are thought to move along a three-dimensionally curved path within the positive electrode active material layer.

[0063] As will be described in detail later, the mixture for all-solid-state lithium-ion batteries of this embodiment can be used as a material for the positive electrode active material layer (positive electrode active material layer for all-solid-state lithium-ion batteries) in the positive electrode of an all-solid-state lithium-ion battery. The LGPS-based sulfide solid electrolyte contained in the mixture for all-solid-state lithium-ion batteries of this embodiment is preferable because it has excellent ionic conductivity and enables smooth lithium ion movement in the positive electrode active material layer for all-solid-state lithium-ion batteries.

[0064] Here, in the mixture for the all-solid-state lithium-ion battery of this embodiment, the ratio of crystalline phase A and crystalline phase B in the LGPS-based sulfide solid electrolyte is expressed as the peak intensity ratio of the diffraction peaks measured by X-ray diffraction, I B / I A It is specified as <0.50. B / I A When the value is 0.50 or higher, the proportion of crystalline phase A, which has high ion conductivity, is low, so lithium ion conduction in the positive electrode active material layer for all-solid-state lithium-ion batteries becomes the rate-limiting factor, and a high discharge capacity cannot be obtained.

[0065] In contrast, the mixture for all-solid-state lithium-ion batteries is I B / I A By including an LGPS-based sulfide solid electrolyte with a value of less than 0.50, lithium ion conduction within the positive electrode active material layer for all-solid-state lithium-ion batteries is promoted, making it easier to obtain a high discharge capacity.

[0066] LGPS-based sulfide solid electrolytes contain elements M2, M3, and S. Element M2 is at least one selected from the group consisting of Li, Na, K, Mg, Ca, and Zn. All elements of element M2 function as conduction ions. Among these, element M2 is preferably Li from the viewpoint of providing a solid electrolyte useful for all-solid-state lithium-ion batteries.

[0067] Further, M2 above is a monovalent element (e.g., Li, Na, K), and a portion thereof may be substituted with a divalent or higher element (e.g., Mg, Ca, Zn). This facilitates the migration of monovalent elements and improves ionic conductivity.

[0068] The element M3 is at least one selected from the group consisting of P, Sb, Si, Ge, Sn, B, Al, Ga, In, Ti, Zr, V and Nb. The element M3 is preferably at least one element selected from the group consisting of P, Ge, Al, Zr, Sn and B, and more preferably at least one of P and Ge. Further, M3 above may be two or more elements.

[0069] In the present embodiment, it is preferable that the element M2 is Li, and the elements M3 are Ge and P.

[0070] The LGPS-based sulfide solid electrolyte preferably contains Li, Ge, P and S. The composition of such an LGPS-based sulfide compound is not particularly limited as long as it is a composition capable of obtaining a predetermined I B / I A value, but it preferably satisfies the composition of Li (4-x) Ge (1-x) P x S4, wherein x satisfies 0<x<1. When this composition is satisfied, a sulfide compound with high Li ion conductivity can be obtained.

[0071] Further, in Li (4-x) Ge (1-x) P x S4, x represents a predetermined I B / I AThere is no particular limitation as long as the value of can be obtained, for example, it is preferable to satisfy 0.4≦x, more preferable to satisfy 0.5≦x, and still more preferable to satisfy 0.6≦x. On the other hand, it is preferable that x satisfies x≦0.8, and more preferable that x satisfies x≦0.75. The above upper limit and lower limit of x can be combined arbitrarily. Examples of combinations include 0.4≦x≦0.8, 0.5≦x≦0.8, and 0.6≦x≦0.75, and among these, it is preferable to satisfy 0.5≦x≦0.8.

[0072] When x satisfies the above range, I B / I A value can be made smaller. Thereby, a solid electrolyte with further excellent Li ion conductivity can be obtained.

[0073] The composition of the LGPS-based sulfide solid electrolyte can be analyzed by the following method.

[0074] [Composition Analysis of LGPS-based Sulfide Solid Electrolyte] For composition analysis of an LGPS-based sulfide solid electrolyte, the LGPS-based sulfide solid electrolyte separated from a mixture by the method described in the above [Separation Method] is dissolved in an aqueous KOH solution, and then analyzed using an inductively coupled plasma optical emission spectrometer (e.g., SPS3000, manufactured by SII Nanotechnology Inc.).

[0075] X-ray diffraction measurement for an LGPS-based sulfide solid electrolyte using CuKα radiation is performed by the method described in the following [X-ray Diffraction Measurement Method for LGPS-based Sulfide Solid Electrolyte].

[0076] [X-ray Diffraction Measurement Method for LGPS-based Sulfide Solid Electrolyte] X-ray diffraction measurement is performed on the LGPS-based solid electrolyte separated from the mixture by the method described in the above [Separation Method]. X-ray diffraction of LGPS-based sulfide solid electrolytes is measured using an X-ray diffractometer. Measurements are performed at 25°C. For example, the Rigaku SmartLab X-ray diffractometer can be used.

[0077] The obtained X-ray diffraction pattern is then subjected to peak searching using X-ray analysis software to obtain the diffraction pattern. For example, Rigaku's integrated powder X-ray analysis software PDXL2 can be used as X-ray analysis software.

[0078] The mass ratio of the lithium metal composite oxide and the LGPS-based sulfide solid electrolyte in the mixture is preferably 60:40 to 95:5, more preferably 65:35 to 92:8, and even more preferably 68:32 to 90:10, with the total amount of lithium metal composite oxide and LGPS-based sulfide solid electrolyte being 100.

[0079] When the mass ratio of the LGPS-based sulfide solid electrolyte in the mixture is 40% or less, the volume ratio of the lithium metal composite oxide does not become too small when converted to volume, and a sufficient volumetric energy density can be ensured for the resulting all-solid-state lithium-ion battery. Therefore, such a mixture for all-solid-state lithium-ion batteries is suitable as a material for batteries used to power mobile devices.

[0080] Furthermore, when the mass ratio of LGPS-based sulfide solid electrolyte in the mixture is 5% or more, the volume ratio of LGPS-based sulfide solid electrolyte in the mixture will be approximately 10% or more when converted to a volume basis. In a positive electrode active material layer for an all-solid-state lithium-ion battery using such an all-solid-state lithium-ion battery mixture as the material, sufficient contact between the LGPS-based sulfide solid electrolytes, which serve as the lithium ion migration pathways, can be ensured, enabling smooth charging and discharging.

[0081] As a result, when the mass ratio of lithium metal composite oxide to LGPS-based sulfide solid electrolyte satisfies the above range, the lithium metal composite oxide and the LGPS-based sulfide solid electrolyte make good contact, improving Li ion conductivity and enabling a high-performance all-solid-state lithium-ion battery.

[0082] The mass ratio of the positive electrode active material to the solid electrolyte in the mixture can be measured by the following method.

[0083] [Method for measuring the mass ratio of an array] The mass ratio of the lithium metal composite oxide and LGPS-based sulfide solid electrolyte separated from the mixture by the method described in [Separation Method] above is calculated by measuring the respective masses (g).

[0084] The mixture may further contain a conductive material. Carbon materials can be used as the conductive material. Examples of carbon materials include graphite powder, carbon black (e.g., acetylene black), and fibrous carbon materials. If the mixture contains a conductive material, the proportion of the conductive material in the total amount of the mixture is, for example, 1 part by mass or more and 10 parts by mass or less.

[0085] The mixture of this embodiment, by combining a lithium-rich lithium metal composite oxide satisfying compositional formula (1) with a highly ionically conductive LGPS-based sulfide solid electrolyte, enables high-capacity all-solid-state lithium-ion batteries. Furthermore, it was found to exhibit the unexpected effect of excellent charge-discharge cycle characteristics under high temperature and high voltage conditions.

[0086] The charge-discharge cycle characteristics are evaluated by forming a positive electrode active material layer using the above mixture to create an all-solid-state lithium-ion battery, and then conducting charge-discharge tests under the conditions shown below using the fabricated all-solid-state lithium-ion battery.

[0087] (Charge / discharge conditions) Test temperature: 60℃ (Initial charge / discharge) Maximum charging voltage: 4.0V, charging current density: 0.16mA / cm² 2 Cutoff current density 0.08 mA / cm² 2 Constant current-constant voltage charging Minimum discharge voltage: 1.4V, Discharge current density: 0.16mA / cm² 2 , constant current discharge (Charge-discharge cycle test) Maximum charging voltage: 4.0V, charging current density: 1.6mA / cm² 2 Cutoff current density 0.08 mA / cm² 2 Constant current-constant voltage charging Minimum discharge voltage: 1.4V, Discharge current density: 1.6mA / cm² 2 , constant current discharge 20 cycles

[0088] A discharge capacity of 200 mAh / g or higher on the first discharge is considered to be high. Furthermore, the ratio of the discharge capacity at the 10th cycle to the discharge capacity at the first discharge in the charge-discharge cycle test is defined as the discharge capacity retention rate (%), and a discharge capacity retention rate of 85% or higher is considered to be excellent in terms of charge-discharge cycle characteristics.

[0089] ≪Method for producing lithium metal composite oxides≫ A method for producing lithium metal composite oxide comprises the steps of obtaining a precursor and obtaining lithium metal composite oxide.

[0090] [Process for obtaining the precursor] The precursor serves as a raw material for lithium metal composite oxides. The process for obtaining the precursor will be explained. The process for obtaining the precursor comprises a nucleation step, a nucleation growth step, a dehydration step, and a drying step.

[0091] The precursor is produced by a semi-continuous process (semi-batch process). Specifically, the process involves first generating nuclei for precursor particles, then temporarily stopping the supply of all raw material liquids, and finally allowing the nuclei to grow.

[0092] Examples of precursors include metal composite hydroxides containing Ni, Co, and Mn.

[0093] Examples of the metal raw material liquid for producing a precursor containing Ni, Co, and Mn include a nickel salt solution, a cobalt salt solution, and a manganese salt solution.

[0094] Hereinafter, an example of producing a metal composite hydroxide containing Ni, Co, and Mn as a precursor will be described. A metal composite hydroxide containing Ni, Co, and Mn may sometimes be referred to as a nickel-cobalt-manganese metal composite hydroxide.

[0095] • Nucleation step A metal raw material mixture and a complexing agent are reacted to obtain Ni 1-x-y Co x Mn y O w (OH) 2-w which is represented by (0<1-x-y, 0<x, 0<y, 0<w<1) to generate nuclei of the metal composite hydroxide. The metal raw material mixture is a mixed liquid of a nickel salt solution, a cobalt salt solution, and a manganese salt solution.

[0096] The metal raw material mixture, the complexing agent, and an alkaline aqueous solution are each continuously and simultaneously supplied into a reaction tank equipped with a stirrer. Nuclei are generated thereby.

[0097] In the semi-continuous method, in order to adjust the pH value of the mixed liquid containing the metal raw material mixture and the complexing agent, an alkaline aqueous solution is added to the mixed liquid before the pH of the mixed liquid changes from alkaline to neutral. Sodium hydroxide or potassium hydroxide can be used for the alkaline aqueous solution.

[0098] Note that the pH value in the present specification is defined as a value measured when the temperature of the mixed liquid is 40°C. The pH of the mixed liquid is measured when the temperature of the mixed liquid sampled from the reaction tank reaches 40°C.

[0099] When the temperature of the sampled mixed liquid is lower than 40°C, the mixed liquid is heated, and the pH is measured when the temperature reaches 40°C. When the temperature of the sampled mixed liquid is higher than 40°C, the mixed liquid is cooled, and the pH is measured when the temperature reaches 40°C.

[0100] During the reaction, the temperature of the reaction vessel is controlled to be, for example, between 20°C and 80°C, preferably between 30°C and 70°C.

[0101] Furthermore, in the nucleation process, the pH value in the reaction vessel is controlled to be, for example, within a range of pH 10 to pH 13, preferably pH 11 to pH 13.

[0102] In the nucleation process, the substances in the reaction vessel are stirred and mixed.

[0103] In the nucleation process, the concentration of the complexing agent in the reaction vessel is controlled to be, for example, within a range of 5.0 g / L to 15.0 g / L.

[0104] ·Nucle growth process After the liquid supply is stopped, the metal raw material mixture, complexing agent, and alkaline aqueous solution are continuously and simultaneously supplied to the same reaction vessel in which the nucleation process was carried out. This causes the nuclei to grow.

[0105] The concentration of the complexing agent in the reaction vessel during the nuclear growth process is preferably 12.0 g / L or more and 15.0 g / L or less. In the nuclear growth process, the pH is controlled to be, for example, between 9 and 12, preferably between 9 and 11.5.

[0106] The reaction vessel uses an overflow type to separate the generated nuclei. The generated nuclei overflow from the reaction vessel and settle and concentrate in a sedimentation tank connected to the overflow pipe. The concentrated nuclei are refluxed back into the reaction vessel, where they are grown again.

[0107] In the nucleation and nucleation growth processes, the oxygen concentration in the reaction vessel is preferably 10% or less. One way to achieve an oxygen concentration of 10% or less is to circulate an inert gas such as nitrogen into the reaction vessel.

[0108] The nickel salt used as the solute in the above nickel salt solution is not particularly limited, but for example, one or more of nickel sulfate, nickel nitrate, nickel chloride, and nickel acetate can be used.

[0109] As the cobalt salt solute in the above cobalt salt solution, one or more of the following can be used: cobalt sulfate, cobalt nitrate, cobalt chloride, and cobalt acetate.

[0110] As the solute of the above manganese salt solution, one or more of the following can be used: manganese sulfate, manganese nitrate, manganese chloride, and manganese acetate.

[0111] The above metal salts are Ni 1-x-y Co x Mn y O w (OH) 2-w It is used in proportions corresponding to the composition ratio. That is, each metal salt is used such that the atomic ratio of Ni in the solute of the nickel salt solution, Co in the solute of the cobalt salt solution, and Mn in the solute of the manganese salt solution is Ni 1-x-y Co x Mn y O w (OH) 2-w A quantity that corresponds to the composition ratio of 1-xy:x:y is used.

[0112] Furthermore, the solvent for the nickel salt solution, cobalt salt solution, and manganese salt solution is preferably water.

[0113] Complexing agents are compounds capable of forming complexes with nickel ions, cobalt ions, and manganese ions in aqueous solution. Examples of complexing agents include ammonium ion suppliers, hydrazine, ethylenediaminetetraacetic acid, nitrilotriacetic acid, uracildiacetic acid, and glycine.

[0114] For example, ammonium salts such as ammonium hydroxide, ammonium sulfate, ammonium chloride, ammonium carbonate, and ammonium fluoride can be used as ammonium ion suppliers.

[0115] Through the above process, a slurry containing nickel-cobalt-manganese metal composite hydroxide is obtained as a metal composite hydroxide-containing slurry.

[0116] ·Dehydration process After the above reaction, the resulting metal composite hydroxide-containing slurry is washed and dried to obtain a precursor as nickel-cobalt-manganese metal composite hydroxide.

[0117] When isolating the precursor, a method of dehydrating the metal complex hydroxide-containing slurry by centrifugation or suction filtration is preferred.

[0118] The precursor obtained by dehydration is preferably washed with a washing solution containing water or alkali. In this embodiment, washing with a washing solution containing alkali is preferred, and washing with a sodium hydroxide solution is more preferred.

[0119] ·Drying process The precursor obtained by the above dehydration process is dried in an air atmosphere at a temperature between 105°C and 200°C for 1 to 20 hours.

[0120] In the above example, a metal composite hydroxide is produced as a precursor, but a metal composite oxide may also be prepared. The metal composite oxide can be obtained by heating the metal composite hydroxide.

[0121] [Process for obtaining lithium metal composite oxides] The lithium metal composite oxide comprises a mixing step of mixing the precursor obtained by the aforementioned step with a lithium compound to obtain a mixture, and a calcination step of calcining the obtained mixture.

[0122] ·Mixing process In this step, a precursor and a lithium compound are mixed to obtain a mixture.

[0123] ·Lithium compound As the lithium compound, any one of lithium carbonate, lithium nitrate, lithium acetate, lithium hydroxide, lithium oxide, lithium chloride, and lithium fluoride, or a mixture of two or more thereof can be used. Among these, either one or both of lithium hydroxide and lithium carbonate are preferred.

[0124] A method for mixing the precursor and the lithium compound will be described. The precursor and the lithium compound are mixed in consideration of the composition ratio of the final target product. For example, when a nickel-cobalt-manganese metal composite hydroxide is used, the lithium compound and the metal composite hydroxide are used in a proportion corresponding to the composition ratio of aLi₂MnO₃·(1-a)LiM¹O₂ (0.1<a<1). In addition, in order to produce a lithium metal composite oxide with excess Li (molar content ratio exceeding 1), mixing is performed at a ratio where the molar ratio of Li contained in the lithium compound to the metal elements contained in the metal composite hydroxide exceeds 1.1, preferably 1.3 or more.

[0125] ·Firing step A lithium metal composite oxide is obtained by firing a mixture of the precursor and the lithium compound. For firing, dry air, an oxygen atmosphere, an inert atmosphere, or the like may be used depending on the desired composition.

[0126] The firing step may be only one firing operation, or may have a plurality of firing stages. When there are a plurality of firing stages, the step of firing at the highest temperature is referred to as main firing. Before the main firing, preliminary firing at a temperature lower than that of main firing may be performed.

[0127] The firing temperature (maximum holding temperature) of main firing is the aforementioned 020 / I 003Furthermore, from the viewpoint of controlling the specific surface area within a predetermined range, a temperature of 800°C or higher is preferred, 850°C or higher is more preferred, and 880°C or higher is particularly preferred. Also, from the viewpoint of suppressing excessive sintering of lithium metal composite oxide particles, a temperature of 1200°C or lower is preferred, 1100°C or lower is more preferred, and 1050°C or lower is particularly preferred.

[0128] The upper and lower limits of the maximum holding temperature for the final firing can be arbitrarily combined. Examples of combinations include 800°C to 1200°C, 850°C to 1100°C, and 880°C to 1050°C.

[0129] The firing temperature for the initial firing should be lower than the firing temperature for the final firing; for example, a range of 350°C to less than 700°C is acceptable.

[0130] After the calcination process, the material is crushed and sieved as appropriate to obtain a lithium metal composite oxide.

[0131] ≪Method for producing LGPS-based sulfide solid electrolytes≫ The LGPS-based sulfide solid electrolyte can be obtained by the method for producing a sulfide solid electrolyte material described in Japanese Patent No. 5527673.

[0132] More specifically, it can be manufactured by either of the following methods (1) or (2). (1) A crystalline ion-conducting material is synthesized using a raw material composition containing the elements M2, M3, and S mentioned above. The crystallinity of the ion-conducting material is then reduced by mechanical milling, and the ion-conducting material with reduced crystallinity is heated. (2) Using a raw material composition containing the elements M2, M3, and S mentioned above, an amorphous ion-conducting material is synthesized by mechanical milling, and the amorphous ion-conducting material is heated.

[0133] By heating the above-mentioned ion-conducting material with reduced crystallinity or the above-mentioned amorphous ion-conducting material, the crystallinity can be improved, and a highly ion-conductive crystalline phase A can be locally precipitated. This yields an LGPS-based sulfide solid electrolyte that satisfies (A) above and preferably has peaks at the positions of 2θ=17.38±0.50°, 2θ=23.56±0.50°, 2θ=23.96±0.50°, 2θ=24.93±0.50°, 2θ=29.07±0.50°, 2θ=31.71±0.50°, 2θ=32.66±0.50°, and 2θ=33.39±0.50°.

[0134] By adjusting the mechanical milling conditions described above, the amount of "ion-conducting material with reduced crystallinity" (above (1)) or "amorphous ion-conducting material" (above (2)) can be controlled, and LGPS-based sulfide solid electrolytes that satisfy the above requirements (A) and (B) can be produced. The mechanical milling conditions can be adjusted by changing the size and amount of media used, the operating conditions of the milling equipment such as a vibrating mill (rotation speed, operating time), etc. The mechanical milling conditions should be set in advance by conducting preliminary experiments.

[0135] The heating temperature is not particularly limited, but it is preferably a temperature above the crystallization temperature of crystalline phase A. Specifically, the heating temperature is preferably 300°C or higher, more preferably 350°C or higher, even more preferably 400°C or higher, and particularly preferably 450°C or higher. Furthermore, the heating temperature is preferably 1000°C or lower, more preferably 700°C or lower, even more preferably 650°C or lower, and particularly preferably 600°C or lower.

[0136] Furthermore, it is preferable to adjust the heating time as appropriate to obtain the desired LGPS-based sulfide solid electrolyte.

[0137] In this embodiment, heating is preferably performed under an inert gas atmosphere or in a vacuum, from the viewpoint of preventing oxidation.

[0138] ≪Method for producing the mixture≫ A mixture is obtained by mixing the lithium metal composite oxide obtained by the above method with an LGPS-based sulfide solid electrolyte. The mixing method can be dry mixing or wet mixing. In the case of wet mixing, first, a mixture of lithium metal composite oxide and LGPS-based sulfide solid electrolyte powders is dispersed in an organic solvent to obtain a slurry. For example, heptane can be used as an organic solvent.

[0139] Next, the obtained slurry is dried to obtain a mixture. When producing a mixture containing a conductive material, a slurry is obtained by dispersing a mixed powder of lithium metal composite oxide, LGPS-based sulfide solid electrolyte, and conductive material in an organic solvent.

[0140] <Positive electrode active material layer for all-solid-state lithium-ion batteries> The positive electrode active material layer for the all-solid-state lithium-ion battery of this embodiment will be described with reference to the drawings. Figure 1 is a schematic diagram showing the stacked structure of an all-solid-state lithium-ion battery. The laminate 100 shown in Figure 1 has a positive electrode 110, a negative electrode 120, and a solid electrolyte layer 130.

[0141] The positive electrode 110 comprises a positive electrode active material layer 111 and a positive electrode current collector 112.

[0142] The positive electrode active material layer 111 contains the mixture for the all-solid-state lithium-ion battery of this embodiment. The positive electrode active material layer 111 may also contain a conductive material and a binder.

[0143] The negative electrode 120 comprises a negative electrode active material layer 121 and a negative electrode current collector 122. The solid electrolyte layer 130 contains a solid electrolyte.

[0144] <All-solid-state lithium-ion battery> Figure 2 is a schematic diagram showing the overall structure of an all-solid-state lithium-ion battery. The all-solid-state lithium secondary battery 1000 shown in Figure 2 has a laminate 100 having a positive electrode 110, a negative electrode 120, and a solid electrolyte layer 130, and an outer casing 200 that houses the laminate 100.

[0145] The laminated body 100 may have an external terminal 113 connected to the positive electrode current collector 112 and an external terminal 123 connected to the negative electrode current collector 122. In addition, the all-solid-state lithium secondary battery 1000 may have a separator between the positive electrode 110 and the negative electrode 120.

[0146] Furthermore, the all-solid-state lithium-ion battery 1000 may have a bipolar structure in which a positive electrode active material and a negative electrode active material are arranged on both sides of the current collector. A specific example of a bipolar structure is the structure described in JP-A-2004-95400. The materials constituting each component will be described later.

[0147] The all-solid-state lithium-ion battery 1000 further includes an insulator (not shown) that insulates the laminate 100 from the outer casing 200 and a seal (not shown) that seals the opening 200a of the outer casing 200.

[0148] The outer casing 200 can be a container formed from a highly corrosion-resistant metal material such as aluminum, stainless steel, or nickel-plated steel. Alternatively, the outer casing 200 can be a container made by processing a laminate film with corrosion-resistant treatment applied to at least one side into a bag shape.

[0149] Examples of shapes for the all-solid-state lithium-ion battery 1000 include coin-shaped, button-shaped, paper-shaped (or sheet-shaped), cylindrical, rectangular, or laminated (pouch-shaped).

[0150] Although the all-solid-state lithium-ion battery 1000 is shown in one example configuration having a single stacked body 100, this embodiment is not limited to this configuration. The all-solid-state lithium-ion battery 1000 may also have a configuration in which the stacked body 100 is used as a unit cell, and multiple unit cells (stacked bodies 100) are sealed inside the outer casing 200.

[0151] The following describes each component in turn.

[0152] (positive electrode) The positive electrode 110 comprises a positive electrode active material layer 111 and a positive electrode current collector 112.

[0153] The positive electrode active material layer 111 contains a mixture that is one embodiment of the present invention as described above. The positive electrode active material layer 111 may also contain a conductive material and a binder.

[0154] (Conductive materials and binders) As the conductive material in the positive electrode active material layer 111, a carbon material can be used. Examples of carbon materials include graphite powder, carbon black (e.g., acetylene black), and fibrous carbon materials.

[0155] The proportion of conductive material in the positive electrode mixture is preferably 1 to 20 parts by mass per 100 parts by mass of positive electrode active material.

[0156] A thermoplastic resin can be used as the binder. Examples of such thermoplastic resins include polyimide resins; polyvinylidene fluoride (hereinafter sometimes referred to as PVdF); fluororesins such as polytetrafluoroethylene; polyolefin resins such as polyethylene and polypropylene; and resins described in WO2019 / 098384A1 or US2020 / 0274158A1.

[0157] (Positive electrode current collector) As the positive electrode current collector 112 of the positive electrode 110, a strip-shaped member made of a metal material such as Al, Ni, or stainless steel can be used.

[0158] One method for supporting the positive electrode active material layer 111 on the positive electrode current collector 112 is to pressure-molde the positive electrode active material layer 111 on the positive electrode current collector 112. Cold pressing or hot pressing can be used for pressure molding.

[0159] Alternatively, a mixture of positive electrode active material, solid electrolyte, conductive material, and binder may be formed into a paste using an organic solvent to form a positive electrode mixture, and the resulting positive electrode mixture may be applied to at least one surface of the positive electrode current collector 112, dried, and pressed to fix it, thereby supporting the positive electrode active material layer 111 on the positive electrode current collector 112.

[0160] Alternatively, a mixture of positive electrode active material, solid electrolyte, and conductive material may be formed into a paste using an organic solvent to create a positive electrode mixture. This mixture may then be applied to at least one surface of the positive electrode current collector 112, dried, and sintered to support a positive electrode active material layer 111 on the positive electrode current collector 112.

[0161] Examples of organic solvents that can be used in the cathode mixture include heptane and N-methyl-2-pyrrolidone (hereinafter sometimes referred to as NMP).

[0162] Methods for applying the positive electrode mixture to the positive electrode current collector 112 include, for example, slit die coating, screen coating, curtain coating, knife coating, gravure coating, and electrostatic spraying.

[0163] The positive electrode 110 can be manufactured using the methods described above.

[0164] (Negative electrode) The negative electrode 120 comprises a negative electrode active material layer 121 and a negative electrode current collector 122. The negative electrode active material layer 121 contains a negative electrode active material. The negative electrode active material layer 121 may also contain a solid electrolyte and a conductive material. The negative electrode active material, negative electrode current collector, solid electrolyte, conductive material, and binder can be those described above.

[0165] Methods for supporting the negative electrode active material layer 121 on the negative electrode current collector 122 include, as in the case of the positive electrode 110, a method by pressure molding, a method by applying a paste-like negative electrode mixture containing the negative electrode active material onto the negative electrode current collector 122, drying it, and then pressing it to bond it, and a method by applying a paste-like negative electrode mixture containing the negative electrode active material onto the negative electrode current collector 122, drying it, and then sintering it.

[0166] (solid electrolyte layer) The solid electrolyte layer 130 is preferably an LGPS-based sulfide solid electrolyte contained in the mixture of this embodiment described above, but it may also be a different solid electrolyte. If a different solid electrolyte is used, a sulfide-based solid electrolyte different from the LGPS-based sulfide solid electrolyte contained in the mixture is preferred.

[0167] When using a sulfide-based solid electrolyte different from the LGPS-based sulfide solid electrolyte contained in the mixture, it is preferable to laminate the positive electrode active material layer and the solid electrolyte layer and then hot press them in order to familiarize the interface between the solid electrolyte layer and the positive electrode active material layer.

[0168] Examples of sulfide-based solid electrolytes include Li2S-P2S5 compounds, Li2S-SiS2 compounds, Li2S-GeS2 compounds, Li2S-B2S3 compounds, LiI-Si2S-P2S5 compounds, LiI-Li2S-P2O5 compounds, LiI-Li3PO4-P2S5 compounds, and Li 10 GeP2S 12 Examples include compound systems.

[0169] In this specification, the term "system compound" referring to sulfide-based solid electrolytes is used as a general term for solid electrolytes that mainly contain the raw materials such as "Li2S" and "P2S5" listed before the term "system compound." For example, Li2S-P2S5 system compounds include solid electrolytes that mainly contain Li2S and P2S5, and also contain other raw materials. The proportion of Li2S in a Li2S-P2S5 system compound is, for example, 50 to 90% by mass of the entire Li2S-P2S5 system compound. The proportion of P2S5 in a Li2S-P2S5 system compound is, for example, 10 to 50% by mass of the entire Li2S-P2S5 system compound. In addition, the proportion of other raw materials in a Li2S-P2S5 system compound is, for example, 0 to 30% by mass of the entire Li2S-P2S5 system compound. Furthermore, Li2S-P2S5 system compounds also include solid electrolytes in which the mixing ratio of Li2S and P2S5 is different.

[0170] Li2S-P2S5 compounds include Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, Li2S-P2S5-LiI-LiBr, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, and Li2S-P2S5-Z m S n Examples include: (m and n are positive numbers. Z is Ge, Zn, or Ga.)

[0171] Li2S-SiS2 compounds include Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-SiS2-P2S5-LiCl, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li2SO4, and Li2S-SiS2-Li x MO y Examples include: (x and y are positive numbers. M is P, Si, Ge, B, Al, Ga, or In.)

[0172] Examples of Li2S-GeS2-based compounds include Li2S-GeS2 and Li2S-GeS2-P2S5.

[0173] The sulfide-based solid electrolyte may be a crystalline material or an amorphous material.

[0174] The solid electrolyte layer 130 can be formed by depositing an inorganic solid electrolyte onto the surface of the positive electrode active material layer 111 of the positive electrode 110 by sputtering.

[0175] Furthermore, the solid electrolyte layer 130 can be formed by applying a paste-like mixture containing a solid electrolyte to the surface of the positive electrode active material layer 111 of the positive electrode 110 described above, and drying it. After drying, the mixture may be press-molded and then further pressurized by cold isostatic pressing (CIP) to form the solid electrolyte layer 130.

[0176] The laminate 100 can be manufactured by laminating the negative electrode 120 onto the solid electrolyte layer 130 provided on the positive electrode 110, using a known method, such that the negative electrode active material layer 121 is in contact with the surface of the solid electrolyte layer 130.

[0177] In an all-solid-state lithium-ion battery with the above configuration, since it includes the mixture of this embodiment, it is possible to provide an all-solid-state lithium-ion battery with a large capacity.

[0178] <Mobile> This embodiment is a mobile device equipped with the all-solid-state lithium-ion battery of the above-described embodiment and driven by the all-solid-state lithium-ion battery. Examples of mobile devices include automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal mobility devices, airplanes, ships, robots (mobile robots), construction machinery, and agricultural machinery (tractors).

[0179] Airplanes are preferred as the mode of transport. In this specification, "airplane" includes "airplanes that can carry people and be used for aviation purposes" as defined in the Aviation Act, and unmanned aircraft powered by all-solid-state lithium-ion batteries. Examples of unmanned aircraft powered by all-solid-state lithium-ion batteries include remotely controlled unmanned aircraft, such as drones and unmanned helicopters for pesticide spraying.

[0180] <Battery for mobile vehicle propulsion> This embodiment is a mobile power supply battery comprising the all-solid-state lithium-ion battery of the above embodiment and an insulating sheet covering the all-solid-state lithium-ion battery. It is preferable that the entire all-solid-state lithium-ion battery is covered with the insulating sheet.

[0181] The thermal conductivity of the insulation sheet is 1 mW / mK or more and 100 mW / mK or less, preferably 2 mW / mK or more and 50 mW / mK or less.

[0182] The thickness of the insulation sheet is preferably between 1 mm and 50 mm, and more preferably between 5 mm and 50 mm.

[0183] The battery for mobile vehicle propulsion is a solid-state lithium-ion battery covered with an insulating sheet, which prevents the internal temperature of the battery from becoming extremely low even in low-temperature environments, allowing the battery to operate. Such a mobile vehicle propulsion battery can operate even in environments where the ambient temperature is as low as -85°C to -50°C, and can therefore be used to propel aircraft. [Examples]

[0184] <Manufacturing of all-solid-state lithium-ion batteries> <<Manufacture of mixtures>> A mixture was obtained by the methods described in Examples 1 to 3 and Comparative Examples 1 and 2, which will be described later. The following operations were performed inside a glove box under an argon atmosphere.

[0185] (Fabrication of positive electrode active material layer, LGPS-based sulfide solid electrolyte layer, and all-solid-state lithium-ion battery) 80 mg of LGPS-based sulfide solid electrolyte was placed in a polyethylene terephthalate tube (PET tube, inner diameter 10.2 mm, outer diameter 30 mm, height 20 mm), a SUS rod was inserted, and the tube was pressed at 110 MPa using a uniaxial press (manufactured by Riken Kiki Co., Ltd.) to form a solid electrolyte layer. On one side of the solid electrolyte layer, the mixtures obtained in the examples and comparative examples were placed with a lithium metal composite oxide support of 10 mg / cm³. 2 The materials were weighed and loaded, a SUS rod was inserted, and Al mesh and Al foil were placed on top in order, then uniaxially pressed at 530 MPa. On the other side of the solid electrolyte layer, indium foil (manufactured by Nilaco), lithium metal foil (manufactured by Honjo Metal Co., Ltd.), and copper mesh as a negative electrode current collector were placed, and after uniaxial pressing at 220 MPa, the material was restrained at 350 MPa to fabricate an all-solid-state lithium-ion battery.

[0186] <Charge / Discharge Test> Using the all-solid-state lithium-ion batteries fabricated by the method described above, charge-discharge tests were conducted under the following conditions.

[0187] (Charge / discharge conditions) Test temperature: 60℃ (Initial charge / discharge) Maximum charging voltage: 4.0V, charging current density: 0.16mA / cm² 2 Cutoff current density 0.08 mA / cm² 2 Constant current-constant voltage charging Minimum discharge voltage: 1.4V, Discharge current density: 0.16mA / cm² 2 , constant current discharge (Charge-discharge cycle test) Maximum charging voltage: 4.0V, charging current density: 1.6mA / cm² 2 Cutoff current density 0.08 mA / cm² 2 Constant current-constant voltage charging Minimum discharge voltage: 1.4V, Discharge current density: 1.6mA / cm² 2 , constant current discharge 20 cycles

[0188] If the initial discharge capacity obtained as described above (initial charge / discharge) is 200 mAh / g or higher, it is evaluated as having "high discharge capacity".

[0189] Further, the ratio of the discharge capacity at the 10th cycle in the above (charge-discharge cycle test) to the initial discharge capacity was defined as the discharge capacity retention rate (%), and when the discharge capacity retention rate was 85% or more, it was evaluated as "excellent charge-discharge cycle characteristics under high temperature and high voltage".

[0190] <Method for Separating Mixture> The lithium metal composite oxide and the LGPS-based sulfide solid electrolyte were separated from the mixture by the method described in the above [Separation Method].[

[0191] <Composition Analysis> The composition of the lithium metal composite oxide was analyzed by the method described in the above [Composition Analysis of Lithium Metal Composite Oxide].[ The composition of the LGPS-based sulfide solid electrolyte was analyzed by the method described in the above [Composition Analysis of LGPS-based Sulfide Solid Electrolyte].[

[0192] <Measurement of Specific Surface Area> The specific surface area of the lithium metal composite oxide was measured by the method described in the above [Method for Measuring Specific Surface Area of Lithium Metal Composite Oxide].[

[0193] <X-ray Diffraction Measurement Method> The X-ray diffraction measurement of the lithium metal composite oxide was performed by the method described in the above [X-ray Diffraction Measurement Method for Lithium Metal Composite Oxide].[ The X-ray diffraction measurement of the LGPS-based sulfide solid electrolyte was performed by the method described in the above [X-ray Diffraction Measurement Method for LGPS-based Sulfide Solid Electrolyte].[

[0194] <D 50 Measurement Method> D of the lithium metal composite oxide 50 was measured by the method described in the above [D of Lithium Metal Composite Oxide 50 Measurement Method].[

[0195] <Example 1> <<Production of Lithium Metal Composite Oxide 1>> [Nucleation Step] Using an apparatus comprising a reaction tank equipped with a stirrer and an overflow pipe, a concentration tank connected to the overflow pipe, and a mechanism for circulating from the concentration tank back to the reaction tank, after water was charged into the reaction tank, an aqueous sodium hydroxide solution was added, and the liquid temperature was maintained at 30°C.

[0196] An aqueous nickel sulfate solution, an aqueous cobalt sulfate solution and an aqueous manganese sulfate solution were mixed at a ratio such that the atomic ratio of Ni:Co:Mn was 0.24:0.23:0.53, to prepare a metal raw material mixed solution.

[0197] Next, ammonium sulfate crystals as a complexing agent were charged into the reaction tank, and the concentration of the complexing agent in the reaction tank was adjusted to 12 g / L. Under stirring, the mixed metal raw material solution was continuously added at a liquid feed rate of 12 mL / min, an aqueous ammonium sulfate solution as a complexing agent was continuously added at a liquid feed rate of 0.5 mL / min, and an aqueous sodium hydroxide solution was added dropwise as needed so that the pH of the solution in the reaction tank was 11.7 (measurement temperature: 40°C).

[0198] After 2 hours elapsed from the start of the nucleation step, all liquid feeding was stopped.

[0199] [Nuclear Growth Step] Subsequently, to the reaction tank in which the nucleation step had been performed, the mixed metal raw material solution was continuously added at a liquid feed rate of 10 mL / min, and an aqueous ammonium sulfate solution as a complexing agent was continuously added at a liquid feed rate of 0.5 mL / min. The concentration of the complexing agent in the reaction tank was 12.0 g / L. Additionally, an aqueous sodium hydroxide solution was added dropwise as needed so that the pH of the solution in the reaction tank was 11.0 (measurement temperature: 40°C). After 27 hours elapsed from the start of the nuclear growth step, all liquid feeding was stopped, and the crystallization reaction was terminated.

[0200] The obtained slurry containing nickel-cobalt-manganese composite metal hydroxide was washed, dehydrated, then dried at 105°C for 20 hours and sieved to obtain nickel-cobalt-manganese composite metal hydroxide 1. Nickel-cobalt-manganese composite metal hydroxide 1 and lithium hydroxide powder were weighed and mixed at a ratio such that the molar ratio of Li in the lithium hydroxide powder to Ni, Co and Mn in the precursor was Li / (Ni+Co+Mn) = 1.30, to obtain a mixed raw material. Subsequently, the resulting mixed raw materials were calcined at 900°C for 10 hours under an atmospheric environment to obtain lithium metal composite oxide 1. Compositional analysis was performed, and when matched to compositional formula (1), a = 0.29 and M1 = Ni, Co, Mn were found. The proportion of Ni in M1 was 33 mol%.

[0201] Lithium metal composite oxide 1 has a layered structure and a specific surface area of ​​1.1 m². 2 / g and D 50 It is 4.6 μm, I 020 / I 003 The value was 0.01.

[0202] Using a lithium-containing Nb peroxo complex aqueous solution as the coating raw material liquid, a lithium-niobium composite oxide layer was formed on the surface of lithium metal composite oxide 1 using a rolling fluid coating apparatus (Pawrec Co., Ltd., MP-01).

[0203] Manufacturing of LGPS-based sulfide solid electrolyte 1 Lithium sulfide (Li2S), phosphorus pentasulfide (P2S5), and germanium sulfide (GeS2) were used as starting materials. These powders were mixed in a glove box under an argon atmosphere in the following proportions: 1.9618 g of Li2S, 1.5138 g of P2S5, and 1.5252 g of GeS2 to obtain the raw material composition.

[0204] Next, the raw material composition was molded into pellets, and the resulting pellets were placed in a carbon-coated quartz tube and vacuum-sealed. The pressure inside the vacuum-sealed quartz tube was approximately 10 Pa. The quartz tube was placed in a firing furnace and heated from room temperature to 700°C over 6 hours, maintained at 700°C for 8 hours, and then slowly cooled to room temperature. As a result, Li 3.45 Ge 0.45 P 0.55 A crystalline ion-conducting material (intermediate 1) having the composition of S4 was obtained.

[0205] Next, the obtained ion-conducting material (intermediate 1) was pulverized using a vibratory mill (TI-100, manufactured by CMT Scientific Co., Ltd.). Specifically, approximately 5 g of the ion-conducting material obtained by the above method and an alumina vibrator (φ36.3 mm, height 48.9 mm) were placed in a 10 mL pot, and the process was carried out at a rotation speed of 1440 rpm for 30 minutes. This process reduced the crystallinity of the ion-conducting material.

[0206] An ion-conducting material with reduced crystallinity was molded into pellets, and the resulting pellets were placed in a quartz tube and vacuum-sealed. The pressure inside the vacuum-sealed quartz tube was approximately 10 Pa. The quartz tube was placed in a firing furnace and heated from room temperature to 550°C over 6 hours, maintained at 550°C for 8 hours, and then slowly cooled to room temperature. As a result, Li 3.45 Ge 0.45 P 0.55 A crystalline LGPS-based sulfide solid electrolyte 1 having the composition of S4 was obtained.

[0207] The obtained LGPS-based sulfide solid electrolyte 1 is I B / I A The value was 0.4. LGPS-based sulfide solid electrolyte 1 was found to have peaks at 2θ=20.18°±0.50°, 2θ=20.44°±0.50°, 2θ=26.96°±0.50°, and 2θ=29.58°±0.50° in the diffraction pattern obtained by measurement using CuKα-based X-ray diffraction, and further peaks at 2θ=17.38±0.50°, 2θ=23.56±0.50°, 2θ=23.96±0.50°, 2θ=24.93±0.50°, 2θ=29.07±0.50°, 2θ=31.71±0.50°, 2θ=32.66±0.50°, and 2θ=33.39±0.50° in the diffraction pattern obtained by measurement using CuKα-based X-ray diffraction.

[0208] <<Manufacture of mixtures>> A lithium metal composite oxide 1, having a lithium-niobium composite oxide layer formed on its surface, an LGPS-based sulfide solid electrolyte 1, and acetylene black as a conductive material were mixed in a mass ratio of 65:30:5 ([Lithium metal composite oxide 1]:[LGPS-based sulfide solid electrolyte 1] = 68.4:31.6 (mass ratio)) to obtain a mixed powder. The obtained mixed powder was dispersed in heptane to obtain a slurry. The obtained slurry was dried at 120°C to obtain mixture 1.

[0209] <Battery Evaluation> The initial discharge capacity of the all-solid-state lithium-ion battery using mixture 1 was 245 mAh / g. Furthermore, the discharge capacity retention rate in the charge-discharge cycle test was 94%.

[0210] <Example 2> Manufacturing of Lithium Metal Composite Oxide 2 Nickel-cobalt-manganese metal composite hydroxide 2 was obtained by the same procedure as in Example 1, except that the atomic ratio of Ni, Co, and Mn in the metal raw material mixture was 0.17:0.17:0.66, and all liquid supply was stopped after 50 hours from the start of the nucleation process to terminate the crystallization reaction.

[0211] Nickel-cobalt-manganese metal composite hydroxide 2 and lithium hydroxide powder were weighed and mixed in a ratio such that the molar ratio of Li in the lithium hydroxide powder to Ni, Co, and Mn in the precursor was Li / (Ni+Co+Mn)=1.50 to obtain a mixed raw material.

[0212] Subsequently, the resulting mixed raw materials were calcined at 900°C for 10 hours under an atmospheric environment to obtain lithium metal composite oxide 2. Compositional analysis was performed, and when matched to compositional formula (1), a = 0.53 and M1 = Ni, Co, Mn were determined. The proportion of Ni in M1 was 33 mol%. Lithium metal composite oxide 2 has a layered structure and a specific surface area of ​​1.3 m². 2 / g and D 50 It is 4.4 μm, I 020 / I 003 The value was 0.10.

[0213] A lithium-niobium composite oxide layer was formed on the surface of lithium metal composite oxide 2 using a rolling fluidized coating apparatus (MP-01, manufactured by Powrex Corporation) with an aqueous lithium-containing Nb peroxo complex solution as the coating raw material solution.

[0214] <<LGPS-based sulfide solid electrolyte>> The same LGPS-based sulfide solid electrolyte 1 as in Example 1 was used.

[0215] <<Production of mixture>> By the same method as in Example 1, lithium metal composite oxide 2 formed with a lithium-niobium composite oxide layer, LGPS-based sulfide solid electrolyte 1 and a conductive material were mixed to produce mixture 2.

[0216] <Battery evaluation> The initial discharge capacity of an all-solid-state lithium ion battery using mixture 2 was 256 mAh / g. Further, the discharge capacity retention rate in a charge-discharge cycle test was 88%.

[0217] <Comparative Example 1> <<Production of lithium metal composite oxide C1>> Nickel-cobalt-manganese metal composite hydroxide C1 was obtained by the same operation as in Example 1, except that the raw material metal mixture was mixed at a ratio such that the atomic ratio of Ni, Co and Mn was 0.34:0.33:0.33, all liquid feeding was stopped and the crystallization reaction was terminated after 50 hours had elapsed from the start of the nucleus growth step.

[0218] Nickel-cobalt-manganese metal composite hydroxide C1 and lithium hydroxide powder were weighed and mixed at a ratio such that the molar ratio of Li in the lithium hydroxide powder to Ni, Co and Mn in the precursor satisfied Li / (Ni+Co+Mn) = 1.03, to obtain a mixed raw material.

[0219] Subsequently, the resulting mixed raw materials were calcined at 950°C for 10 hours under an oxygen atmosphere to obtain lithium metal composite oxide C1. Compositional analysis was performed, and when matched to compositional formula (1), a = 0.03 and M1 = Ni, Co, Mn were determined. The proportion of Ni in M1 was 34 mol%. Lithium metal composite oxide C1 has a layered structure and a specific surface area of ​​0.9 m². 2 / g and D 50 It is 5.0 μm, I 020 / I 003 The value was 0.00.

[0220] Using a lithium-containing Nb peroxo complex aqueous solution as the coating raw material, a lithium-niobium composite oxide layer was formed on the surface of lithium metal composite oxide C1 using a rolling fluid coating apparatus (Pawrec Co., Ltd., MP-01).

[0221] ≪LGPS-based sulfide solid electrolyte≫ For the LGPS-based sulfide solid electrolyte, the same LGPS-based sulfide solid electrolyte 1 as in Example 1 was used.

[0222] <<Manufacture of mixtures>> A mixture C1 was prepared by mixing lithium metal composite oxide C1, LGPS-based sulfide solid electrolyte 1, and a conductive material using the same method as in Example 1.

[0223] <Battery Evaluation> The initial discharge capacity of the all-solid-state lithium-ion battery using mixture C1 was 182 mAh / g. Furthermore, the discharge capacity retention rate in charge-discharge cycle tests was 87%.

[0224] <Example 3> Manufacturing of LGPS-based sulfide solid electrolyte 2 A crystalline ion-conducting material (intermediate 2) was obtained in the same manner as in the production of LGPS-based sulfide solid electrolyte 1, except that a raw material composition consisting of a mixture of 1.9633 g of Li2S, 1.5150 g of P2S5, and 1.5249 g of GeS2 was used.

[0225] A crystalline LGPS-based sulfide solid electrolyte 2 was obtained in the same manner as in the production of LGPS-based sulfide solid electrolyte 1, except that the obtained intermediate 2 was subjected to grinding treatment using a vibratory mill for 45 minutes.

[0226] The resulting LGPS-based sulfide solid electrolyte 2 has a composition of Li 3.45 Ge 0.45 P 0.55 S4, I B / I A The value was 0.2. LGPS-based sulfide solid electrolyte 2 was found to have peaks at 2θ=20.18°±0.50°, 2θ=20.44°±0.50°, 2θ=26.96°±0.50°, and 2θ=29.58°±0.50° in the diffraction pattern obtained by measurement using CuKα-based X-ray diffraction, and further peaks at 2θ=17.38±0.50°, 2θ=23.56±0.50°, 2θ=23.96±0.50°, 2θ=24.93±0.50°, 2θ=29.07±0.50°, 2θ=31.71±0.50°, 2θ=32.66±0.50°, and 2θ=33.39±0.50° in the diffraction pattern obtained by measurement using CuKα-based X-ray diffraction.

[0227] <<Manufacture of mixtures>> A lithium metal composite oxide 2 having a lithium-niobium composite oxide layer formed on it, an LGPS-based sulfide solid electrolyte 2, and a conductive material were mixed in the same manner as in Example 1 to produce mixture 3.

[0228] <Battery Evaluation> The initial discharge capacity of the all-solid-state lithium-ion battery using mixture 3 was 269 mAh / g. Furthermore, the discharge capacity retention rate in the charge-discharge cycle test was 89%.

[0229] <Comparative Example 2> ≪Production of non-LGPS sulfide solid electrolyte 1≫ Lithium sulfide (Li2S) and phosphorus pentasulfide (P2S5) were used as starting materials. These powders were mixed in a glove box under an argon atmosphere at a ratio of 0.9569 g of Li2S and 1.5431 g of P2S5 to obtain the raw material composition.

[0230] Next, 2 g of the raw material composition was placed in a zirconia pot (capacity 45 ml) with 10 zirconia balls (10 mm in diameter) under an argon atmosphere, and the pot was completely sealed. This pot was mounted on a planetary ball mill (Fritsch P7) and mechanical milling was performed for 40 hours at a plate rotation speed of 380 rpm. This yielded an amorphous ion-conductive material with the composition Li3PS4.

[0231] Next, the obtained ion-conductive material was molded into pellets, and these pellets were placed in a quartz tube and vacuum-sealed. The pressure inside the vacuum-sealed quartz tube was approximately 10 Pa. The quartz tube was placed in a firing furnace and heated from room temperature to 280°C over 3 hours, maintained at 280°C for 4 hours, and then slowly cooled to room temperature. This yielded a crystalline non-LGPS-based sulfide solid electrolyte 1 having the composition Li3PS4.

[0232] Non-LGPS sulfide solid electrolyte 1 has a composition of Li3PS4, and in the diffraction pattern obtained by measurement using CuKα-ray X-ray diffraction, it was confirmed that it has a different crystal structure from LGPS sulfide solid electrolytes, as it does not have peaks at the positions of 2θ=20.18°±0.50°, 2θ=20.44°±0.50°, 2θ=26.96°±0.50°, and 2θ=29.58°±0.50°.

[0233] <<Manufacture of mixtures>> A lithium metal composite oxide 1 having a lithium-niobium composite oxide layer formed on it, a non-LGPS-based sulfide solid electrolyte 1, and a conductive material were mixed in the same manner as in Example 1 to produce mixture C2.

[0234] <Battery Evaluation> The initial discharge capacity of the all-solid-state lithium-ion battery using mixture C2 was 180 mAh / g. Furthermore, the discharge capacity retention rate in charge-discharge cycle tests was 38%.

[0235] The results above demonstrate that Examples 1-3 exhibit superior discharge capacity and charge / discharge cycle characteristics under high temperature and high voltage conditions compared to Comparative Examples 1 and 2. [Explanation of Symbols]

[0236] 100: Laminate, 110: Positive electrode, 111: Positive electrode active material layer, 112: Positive electrode current collector, 113: External terminal, 120: Negative electrode, 121: Negative electrode active material layer, 122: Negative electrode current collector, 123: External terminal, 130: Solid electrolyte layer, 200: Outer casing, 200a: Opening, 1000: All-solid-state lithium-ion battery

Claims

1. A mixture for all-solid-state lithium-ion batteries comprising a lithium metal composite oxide and an LGPS-based sulfide solid electrolyte, The lithium metal composite oxide has a layered structure, contains at least Li, Mn, and element M1, and satisfies the following compositional formula (1), The LGPS-based sulfide solid electrolyte contains elements M2, M3, and S. The element M2 is at least one selected from the group consisting of Li, Na, K, Mg, Ca, and Zn. The element M3 is at least one selected from the group consisting of P, Sb, Si, Ge, Sn, B, Al, Ga, In, Ti, Zr, V, and Nb. The LGPS-based sulfide solid electrolyte satisfies the following conditions (A) and (B) in the diffraction pattern obtained by measurement using X-ray diffraction with CuKα rays: A mixture for all-solid-state lithium-ion batteries, wherein the mass ratio of the lithium metal composite oxide to the LGPS-based sulfide solid electrolyte is 60:40 to 95:

5. Alia ２ Mnｯ ３ ・(1-a)LiM1O ２ ・・・(1) (0.1 < a < 1, element M1 is one or more elements selected from the group consisting of Ni, Co, Mn, Fe, Cu, Ti, Na, Mg, Ca, Sr, Ba, B, Al, Si, P, W, Mo, Nb, Zn, Sn, Zr, Cr, Ga, Ge, Pd, Ag, Cd, In, and V) (A) The peaks are located at 2θ = 20.18° ± 0.50°, 2θ = 20.44° ± 0.50°, 2θ = 26.96° ± 0.50°, and 2θ = 29.58° ± 0.50°. (B) I Ｂ / I Ａ <0.50 (I Ａ This is the diffraction intensity of the peak at the position 2θ = 29.58° ± 0.50°, and I Ｂ This represents the diffraction intensity of the peak at the position 2θ = 27.33° ± 0.50°.

2. The LGPS-based sulfide solid electrolyte is a mixture for an all-solid-state lithium-ion battery according to claim 1, satisfying the following (B)-1. (B)-1 I Ｂ / I Ａ ≦0.25

3. The LGPS-based sulfide solid electrolyte has peaks at the following positions in the diffraction pattern obtained by measurement using CuKα-based X-ray diffraction: 2θ = 17.38 ± 0.50°, 2θ = 23.56 ± 0.50°, 2θ = 23.96 ± 0.50°, 2θ = 24.93 ± 0.50°, 2θ = 29.07 ± 0.50°, 2θ = 31.71 ± 0.50°, 2θ = 32.66 ± 0.50°, and 2θ = 33.39 ± 0.50°, according to claim 1 or 2, for an all-solid-state lithium-ion battery mixture.

4. The mixture for an all-solid-state lithium-ion battery according to claim 1 or 2, wherein the element M2 is Li, and the elements M3 are Ge and P.

5. The composition of the LGPS-based sulfide solid electrolyte is Li （４－ｘ） Ge （１－ｘ） P ｘ S ４ A mixture for an all-solid-state lithium-ion battery according to claim 4, satisfying the condition (where x satisfies 0 < x < 1).

6. The mixture for all-solid-state lithium-ion batteries according to claim 5, wherein x satisfies 0.5 ≤ x ≤ 0.

8.

7. The lithium metal composite oxide is a mixture for an all-solid-state lithium-ion battery according to claim 1 or 2, wherein the lithium metal composite oxide satisfies the following (3). 0.01≦I ０２０ / I ００３ ≦0.3 ・・・(3) [I ０２０ This is the integrated intensity of the peak of the (020) plane, which is attributed to the crystal structure of space group C2 / m, in the X-ray diffraction pattern of the lithium metal composite oxide using CuKα rays, and I ００３ This represents the integrated intensity of the peak of the (003) plane, which is attributed to the crystal structure of space group R-3m.

8. The lithium metal composite oxide has a specific surface area of ​​0.3 m². ２ / g or more 2.0m ２ A mixture for all-solid-state lithium-ion batteries according to claim 1 or 2, satisfying the requirement of less than or equal to / g.

9. A positive electrode active material layer for an all-solid-state lithium-ion battery comprising the mixture for all-solid-state lithium-ion batteries described in claim 1 or 2.

10. The positive electrode active material layer for an all-solid-state lithium-ion battery according to claim 9, further comprising a conductive material.

11. An all-solid-state lithium-ion battery comprising: a positive electrode containing a positive electrode active material layer for an all-solid-state lithium-ion battery as described in claim 9; a negative electrode; and a solid electrolyte layer containing a sulfide-based compound sandwiched between the positive electrode and the negative electrode.

12. A mobile body comprising the all-solid-state lithium-ion battery described in claim 11, and driven by the all-solid-state lithium-ion battery.

13. The mobile body according to claim 12, which is an airplane.

14. A mobile power supply battery comprising an all-solid-state lithium-ion battery according to claim 11 and an insulating sheet covering the all-solid-state lithium-ion battery, wherein the thermal conductivity of the insulating sheet is 1 mW / mK or more and 100 mW / mK or less.

15. A battery for driving a mobile device according to claim 14, which drives an airplane.

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