Anode mixture for precipitation type solid secondary battery, anode layer for precipitation type solid secondary battery, precipitation type solid secondary battery and charging method therefor

Abstract

To remarkably improve output characteristics of a precipitation type solid secondary battery even if charged / discharged under conditions of a room temperature and a low outside pressure.SOLUTION: An anode mixture for a precipitation type solid secondary battery contains amorphous carbon, an alloy formation element which forms an alloy with lithium through an electrochemical reaction, and a binder. A content of the amorphous carbon with respect to 100 mass% of a total mass of the amorphous carbon and the alloy formation element is from 25 mass% or more to 90 mass% or less. A half value width (FWHM002) of (002) peak of the carbon measured by X-ray diffraction measurement using Cu-Kα rays of the amorphous carbon is from 4° or more to 6° or less, and an oxygen content of the amorphous carbon is from 0.5 at% or more to 10 at% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a negative electrode mixture for a precipitation-type solid secondary battery, a negative electrode layer for a precipitation-type solid secondary battery, a precipitation-type solid secondary battery, and a charging method thereof. [Background technology]

[0002] An example of a solid-state secondary battery that uses lithium as the negative electrode active material is a deposition-type all-solid-state secondary battery that uses lithium, which is deposited in the negative electrode layer upon charging, as the active material, as shown in Patent Document 1. In such a deposition-type all-solid-state secondary battery, the negative electrode composite contains carbon black, and Patent Document 1 successfully produces an all-solid-state secondary battery that operates well under conditions of 60°C and 4 MPa by setting the nitrogen adsorption specific surface area of ​​this carbon black and the DBP feed amount within predetermined ranges. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-167146 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention was first completed as a result of the inventors' repeated improvements to enable precipitation-type solid state secondary batteries to operate satisfactorily not only under the above-mentioned high temperature and high external pressure conditions but also under room temperature and low external pressure conditions, and the discovery of a negative electrode composite that can significantly improve the output characteristics of precipitation-type solid state secondary batteries even when they are charged and discharged under room temperature and low external pressure conditions. [Means for solving the problem]

[0005] That is, the negative electrode composite for a precipitation-type solid secondary battery, the negative electrode layer for a precipitation-type solid secondary battery, the precipitation-type solid secondary battery, and the charging method thereof according to the present invention are as follows. [1] A battery containing amorphous carbon, an alloying element that forms an alloy with lithium through an electrochemical reaction, and a binder; the content of the amorphous carbon is 25% by mass or more and 90% by mass or less when the total mass of the amorphous carbon and the alloying elements is 100% by mass, The full width at half maximum (FWHM) of the (002) peak of the carbon measured by X-ray diffraction measurement using Cu-Kα radiation of the amorphous carbon 002 ) is between 4° and 6°, The negative electrode composite for a precipitation-type solid secondary battery has an oxygen content of 0.5 at % or more and 10 at % or less, where the entire amorphous carbon is taken as 100 at %. [2] The amorphous carbon has a BET specific surface area of ​​10 m, calculated from the adsorption isotherm measured by adsorbing nitrogen onto the amorphous carbon. 2 / g or more 180m 2 / g or less. [3] The negative electrode mixture for a solid secondary battery according to [1] or [2], wherein the amorphous carbon has an oil absorption of 60 ml / 100 g or more and 400 ml / 100 g or less. [4] The negative electrode mixture for a precipitation type solid secondary battery according to any one of [1] to [3], wherein the amorphous carbon has a volume-based particle size distribution integrated value of 50% (D50) of 50 nm or more and 350 nm or less. [5] The negative electrode mixture for a precipitation-type solid secondary battery according to any one of [1] to [4], wherein the alloying element is at least one selected from the group consisting of gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, indium, and zinc. [6] The negative electrode mixture for a precipitation type solid secondary battery according to any one of [1] to [5], wherein the amorphous carbon is carbon black. [7] A negative electrode current collector and a negative electrode mixture layer laminated on the negative electrode current collector, The negative electrode mixture layer for a precipitation-type solid secondary battery contains the negative electrode mixture according to any one of [1] to [6]. [8] 1 cm of the negative electrode mixture layer 2 The negative electrode layer for a deposition-type solid secondary battery according to [7], wherein the mass per unit area is 0.3 mg or more and 2 mg or less. [9] The negative electrode layer for a deposition-type solid secondary battery according to [7] or [8], wherein the negative electrode mixture layer does not contain a solid electrolyte.

[10] A solid secondary battery comprising a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, The precipitation-type solid state secondary battery, wherein the negative electrode layer is one described in any one of [7] to [9].

[11] The positive electrode layer comprises a positive electrode mixture layer, The precipitation-type solid state secondary battery according to

[10] , wherein a ratio of an initial charge capacity of the positive electrode mixture layer to an initial charge capacity of the negative electrode mixture layer satisfies the requirement of the following mathematical formula (1). 0.01 a: Initial charge capacity of the positive electrode composite layer (mAh) b: Initial charge capacity of the negative electrode composite layer (mAh)

[12] A method for charging a precipitation-type solid state secondary battery, comprising charging the precipitation-type solid state secondary battery according to

[10] or

[11] above to a capacity exceeding the initial charge capacity of the negative electrode mixture layer.

[13] The method for charging a precipitation-type solid secondary battery according to

[12] , wherein the negative electrode mixture layer is charged to a charge capacity that is 2 to 100 times the initial charge capacity.

[14] A method for using a precipitation-type solid state secondary battery according to

[10] or

[11] , wherein the precipitation-type solid state secondary battery is sandwiched between two plates and charged and discharged while applying pressure.

[15] The method for using the precipitation-type solid state secondary battery according to

[14] , wherein the pressure is 0.1 MPa or more and 1 MPa or less.

[16] A method for using the precipitation-type solid state secondary battery according to

[14] or

[15] , wherein the precipitation-type solid state secondary battery according to

[10] or

[11] is charged and discharged at a temperature of 20°C or higher and 30°C or lower. [Effects of the Invention]

[0006] According to the present invention, the output characteristics of a precipitation-type solid secondary battery can be significantly improved even when the battery is charged and discharged under conditions of room temperature and low external pressure. [Brief explanation of the drawings]

[0007] [Figure 1] ​1 is a cross-sectional view showing a schematic configuration of a solid secondary battery according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing a schematic configuration of the solid secondary battery according to the present embodiment in a case where a lithium metal layer is precipitated. [Figure 3] FIG. 2 is a cross-sectional view showing a schematic configuration of the solid secondary battery according to the present embodiment in a case where a lithium metal layer is precipitated. [Figure 4] FIG. 3 is a cross-sectional view showing a schematic configuration of a solid secondary battery according to another embodiment of the present invention. [Figure 5] FIG. 3 is a cross-sectional view showing a schematic configuration of a solid secondary battery according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant explanations will be omitted.

[0009] <1. Basic configuration of the solid secondary battery according to this embodiment> The solid state secondary battery 1 according to this embodiment is, for example, an all-solid state secondary battery including a positive electrode layer 10, a negative electrode layer 20, and a solid electrolyte layer 30, as shown in FIG.

[0010] (1-1. Positive electrode layer) The positive electrode layer 10 includes a positive electrode current collector 11 and a positive electrode composite layer 12. Examples of the positive electrode current collector 11 include a plate-shaped or foil-shaped body made of indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), or an alloy thereof. The positive electrode current collector 11 may be omitted.

[0011] Positive electrode composite layer 12 contains a positive electrode active material and a solid electrolyte. The solid electrolyte contained in positive electrode layer 10 may or may not be the same type as the solid electrolyte contained in solid electrolyte layer 30. Details of the solid electrolyte will be described in the section on solid electrolyte layer 30.

[0012] The positive electrode active material may be any positive electrode active material that can reversibly store and release lithium ions.

[0013] For example, the positive electrode active material can be formed using lithium salts such as lithium cobalt oxide (hereinafter referred to as LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel aluminum oxide (hereinafter referred to as NCA), lithium nickel cobalt manganese oxide (hereinafter referred to as NCM), lithium manganate, lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, sulfur, iron oxide, vanadium oxide, etc. These positive electrode active materials may be used alone or in combination of two or more.

[0014] The positive electrode active material is preferably formed by containing a lithium salt of a transition metal oxide having a layered rock salt structure among the above-mentioned lithium salts. Here, the "layered rock salt structure" refers to a cubic rock salt structure. <111> It is a structure in which oxygen atomic layers and metal atomic layers are regularly arranged alternately in the direction of the crystal, resulting in each atomic layer forming a two-dimensional plane. Also, the "cubic rock salt structure" refers to a sodium chloride structure, which is a type of crystal structure, and specifically refers to a structure in which the face-centered cubic lattices formed by cations and anions are shifted from each other by half the edge of the unit cell.

[0015] Examples of lithium salts of transition metal oxides having such a layered rock salt structure include LiNi x Co y Alz O2(NCA), or LiNi x Co y Mn z Examples include lithium salts of ternary transition metal oxides such as O2(NCM) (where 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1).

[0016] When the positive electrode active material contains a lithium salt of a ternary transition metal oxide having the above-described layered rock salt structure, the energy density and thermal stability of the solid secondary battery 1 can be improved.

[0017] The positive electrode active material may be covered by a coating layer. Here, the coating layer of the present embodiment may be any known coating layer for the positive electrode active material of the solid secondary battery 1. Examples of the coating layer include, for example, Li2O-ZrO2 and the like.

[0018] Further, when the positive electrode active material is formed of a lithium salt of a ternary transition metal oxide such as NCA or NCM and contains nickel (Ni) as the positive electrode active material, the coating layer can increase the capacity density of the solid secondary battery 1 and reduce the metal elution from the positive electrode active material in the charged state. Thereby, the solid secondary battery 1 according to the present embodiment can improve the long-term reliability and cycle characteristics in the charged state.

[0019] Here, examples of the shape of the positive electrode active material include particle shapes such as true spherical and elliptical spherical. Further, the particle size of the positive electrode active material is not particularly limited as long as it is within a range applicable to the positive electrode active material of a conventional solid secondary battery. In addition, the content of the positive electrode active material in the positive electrode layer 10 is not particularly limited as long as it is within a range applicable to the positive electrode layer 10 of a conventional solid secondary battery. [[ID=​​​​​Examples of conductive additives that can be blended into the positive electrode layer 10 include graphite, carbon black, acetylene black, ketjen black, carbon fiber, and metal powder. Examples of binders that can be blended into the positive electrode layer 10 include styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene. Furthermore, known materials generally used in electrodes for solid secondary batteries can be used as fillers, dispersants, ion conductive additives, and the like that can be blended into the positive electrode layer 10.

[0022] The positive electrode layer 10 may contain a liquid electrolyte. In this case, the positive electrode layer 10 does not need to contain a solid electrolyte. Any type of electrolyte may be used as long as it is compatible with lithium-ion batteries. By using a positive electrode layer 10 containing an electrolyte, ionic conduction between the positive electrode active material particles is facilitated, improving output. When the positive electrode layer 10 contains an electrolyte, the solid electrolyte layer 30 is configured to prevent the electrolyte from penetrating into the negative electrode side.

[0023] (1-2. Negative electrode layer) The negative electrode layer 20 includes a negative electrode current collector 21 and a negative electrode mixture layer 22 . The negative electrode current collector 21 is preferably made of a material that does not react with lithium, i.e., that does not form any alloy or compound. Examples of materials that make up the negative electrode current collector 21 include copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The negative electrode current collector 21 may be made of any one of these metals, or may be made of an alloy or clad material of two or more metals. The negative electrode current collector 21 is, for example, in the form of a plate or foil.

[0024] Negative electrode mixture layer 22 contains a negative electrode active material. In this embodiment, the negative electrode active material contains amorphous carbon and an alloying element. The amorphous carbon is preferably carbon black, such as acetylene black, furnace black, or ketjen black. The alloying element is an element that forms an alloy or a compound with lithium through an electrochemical reaction, and specifically includes at least one element selected from the group consisting of gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, indium, and zinc.

[0025] The alloying element is, for example, particulate, and its particle size is preferably 4 μm or less, more preferably 300 nm or less. In this case, the characteristics of the solid secondary battery 1 are further improved. Here, the particle size of the negative electrode active material is, for example, the median diameter (so-called D50) measured using a laser particle size distribution system, or the particle size is measured using a scanning electron microscope (SEM) or a transmission electron microscope (TEM) and calculated as the arithmetic mean diameter of, for example, 100 particles. In the examples and comparative examples described below, the particle size was measured by this method. The lower limit of the particle size is not particularly limited, but may be 10 nm.

[0026] Negative electrode mixture layer 22 may further contain, as an additive, an element that does not form an alloy or compound with lithium. The element that does not form an alloy or compound with lithium can be an element belonging to Period 4 of the Periodic Table, and belonging to Groups 3 to 11. More specifically, the element is one or more elements selected from the group consisting of iron, copper, nickel, and titanium. Only one of these elements may be used, or a combination of two or more of these elements may be used. These elements are preferably granular, and the preferred average primary particle size varies depending on the element, but is preferably, for example, 65 nm to 800 nm. The average primary particle size can be measured using a scanning electron microscope (SEM) or a transmission electron microscope (TEM) and calculated as the arithmetic mean diameter of 100 particles.

[0027] Negative electrode mixture layer 22 may contain a binder. Examples of such binders include styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene. The binder may be composed of one or more of these.

[0028] By including a binder in negative electrode mixture layer 22, it is possible to stabilize negative electrode mixture layer 22 and make it less likely to peel off from negative electrode current collector 21. Furthermore, as will be described in detail later, negative electrode mixture layer 22 is produced by applying a slurry in which the negative electrode mixture constituting negative electrode mixture layer 22 is dispersed onto negative electrode current collector 21 and drying the slurry. By including a binder in negative electrode mixture layer 22, it is possible to stably disperse the negative electrode active material in the above-mentioned slurry.

[0029] When a binder is contained in the negative electrode composite layer 22, the binder content is preferably 0.3% by mass or more and 15% by mass or less, where the total mass of the negative electrode active material is 100% by mass. If the binder content is 0.3% by mass or more, the strength of the film is sufficient and deterioration of the characteristics can be suppressed. If the binder content is 20% by mass or less, deterioration of the characteristics of the solid secondary battery 1 can be suppressed. A more preferable lower limit of the binder content is 1% by mass.

[0030] Negative electrode mixture layer 22 may contain additives used in conventional solid secondary batteries, such as fillers, dispersants, ion conductive agents, and the like, as appropriate.

[0031] (1-3.Solid electrolyte layer) The solid electrolyte layer 30 is laminated between the positive electrode layer 10 and the negative electrode layer 20, and contains a solid electrolyte.

[0032] The solid electrolyte is composed of, for example, a sulfide-based solid electrolyte material and / or an oxide-based solid electrolyte. Examples of sulfide-based solid electrolyte materials include Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element, for example, I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, and Li2 S -SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m and n are positive numbers, Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p and q are positive numbers, and M is P, Si, Ge, B, Al, Ga, or In). Here, the sulfide-based solid electrolyte material is produced by processing the starting material (e.g., Li2S, P2S5, etc.) by a melt quenching method, a mechanical milling method, or the like. Furthermore, these processes may be followed by a heat treatment. The solid electrolyte may be amorphous, crystalline, or a mixture of both.

[0033] Furthermore, as the solid electrolyte, it is preferable to use, among the above-mentioned sulfide solid electrolyte materials, one containing at least sulfur (S), phosphorus (P), and lithium (Li) as constituent elements, and it is particularly preferable to use one containing Li2S-P2S5.

[0034] When a sulfide-based solid electrolyte material containing Li2S-P2S5 is used to form the solid electrolyte, the molar ratio of Li2S to P2S5 may be selected, for example, in the range of Li2S:P2S5=50:50 to 90:10. The solid electrolyte layer 30 may further contain a binder. Examples of binders contained in the solid electrolyte layer 30 include styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene. The binder in the solid electrolyte layer 30 may be the same as or different from the binders in the positive electrode mixture layer 12 and the negative electrode mixture layer 22.

[0035] Examples of oxide-based solid electrolytes include garnet-type composite oxides, perovskite-type oxides, LISICON-type composite oxides, NASICON-type composite oxides, Li-alumina-type composite oxides, LiPON, and oxide glass. Among these oxide-based solid electrolytes, it is preferable to select an oxide-based solid electrolyte that can be stably used with lithium metal. For example, La 0.51 Li 0.34 TiO 2.94 , Li 1.3 Al 10.3 Ti 1.7 (PO4)3, Li7La3Zr2O 12 , 50Li4SiO4·50Li3BO3, Li 2.9 PO 3.3 N 0.46 , Li 3.6 Si 0.6 P 0.4 O4, Li 1.07 Al 0.69 Ti 1.46 (PO4)3, Li 1.5 Al 10.5 Ge 1.5 (PO4)3 is preferred.

[0036] 2. Characteristic Configuration of the Solid State Secondary Battery According to the Present Embodiment The amorphous carbon contained in the negative electrode composite layer 22 of the solid secondary battery 1 according to this embodiment has a full width at half maximum (FWHM) of the (002) peak of carbon measured by X-ray diffraction measurement using Cu-Kα rays. 002 ) is 4° or more and 6° or less. 002 It is more preferable that the FWHM is 4.5° or more and 5.8° or less, and further more preferable that the FWHM is 4.7° or more and 5.5° or less. 002 is an index relating to the crystallinity of amorphous carbon, and in the range of 4° or more and 6° or less, amorphous carbon is considered to be in a state close to an amorphous state and to have a moderate anisotropy. FWHM 002 can be measured in the following way: X-ray diffraction measurements were performed on the carbon powder using an X-ray diffractometer (PANalytical, Empyrean) with a CuKα radiation source and an accelerating voltage and current of 30 kV and 10 mA, respectively. For the X-ray diffraction data obtained by the X-ray diffraction measurement described above, the half-width of the diffraction peaks present at 2θ = 20-30° on the X-ray diffraction pattern is determined using "X'Pert HighScore Plus," the software provided with the X-ray diffraction apparatus.

[0037] In this embodiment, the oxygen content of the amorphous carbon is 0.5 at% or more and 10 at% or less, where the entire amorphous carbon is 100 at%. The oxygen content of the amorphous carbon is more preferably 0.6 at% or more and 5 at% or less, and even more preferably 0.7 at% or more and 4 at% or less. The oxygen content of the amorphous carbon refers to the amount of oxygen-containing functional groups contained in the amorphous carbon, and this oxygen content can be adjusted by known methods such as calcination treatment or acid treatment. The oxygen content of the amorphous carbon can be measured by the following method. A powder sample of amorphous carbon is measured under the following conditions, and the oxygen content can be calculated from the measured O1s binding energy peak (529-536 eV) using the sensitivity coefficient recommended by the instrument manufacturer. (Measurement conditions) Equipment: PHI Quantera SXM X-ray source / X-ray output / analysis area: Single crystal spectroscopic Al Kα line / 50.0W / Φ200μm · Pass Energy :Wide Scan-280.00eV(1.00eV / Step), Narrow Scan-69.00eV(0.125eV / Step) Charge neutralization gun: Ar+, e- Geometry: θ=45° (θ: angle between the sample surface and the detector)

[0038] The BET specific surface area of ​​the amorphous carbon is 10 m 2 / g or more 180m 2 / g or less, and 2 / g or more 100m 2 / g or less is more preferable, and 15m 2 / g or more 60m 2 It is more preferable that the saturation coefficient is 1 / g or less. The BET specific surface area (m 2 The specific surface area (σ) of a sample (μm / g) can be measured using the nitrogen adsorption method (multipoint method) (JIS K6217-2:2017). Specifically, amorphous carbon, such as carbon black, is degassed at high temperature and then cooled to liquid nitrogen temperature under vacuum. Nitrogen gas is then introduced, and after equilibrium is reached, the nitrogen ambient pressure and nitrogen adsorption volume are measured. This measurement is repeated multiple times over a relative pressure range (nitrogen ambient pressure / saturated vapor pressure) of approximately 0.05 to 0.35. The obtained nitrogen ambient pressure and nitrogen adsorption volume values ​​are then applied to the Brunauer-Emmett-Teller (BET) equation to determine the monomolecular adsorption volume (the volume of nitrogen gas adsorbed on the first layer of the sample surface). The nitrogen adsorption specific surface area can be calculated from this monomolecular adsorption volume and the sample mass.

[0039] Furthermore, the oil absorption of the amorphous carbon is preferably 60 ml / 100 g or more and 400 ml / 100 g or less, more preferably 65 ml / 100 g or more and 390 ml / 100 g or less, and even more preferably 65 ml / 100 g or more and 380 ml / 100 g or less.

[0040] The oil absorption of amorphous carbon can be calculated by measuring the oil absorption in accordance with JIS K6217-4:2017. Specifically, oil (dibutyl phthalate (DBP) or paraffin oil) is titrated into a sample agitated by a rotating impeller using a constant-speed burette. As the oil is added, the mixture changes from a free-flowing powder to a slightly viscous mass. The endpoint of the measurement is when the torque generated by the change in viscosity reaches a set value or a certain percentage of the maximum torque obtained from the torque curve. The oil absorption (ml / 100g) can be calculated by dividing the volume (ml) of oil at the endpoint by the mass (g) of the sample and multiplying the result by 100.

[0041] The amorphous carbon preferably has a volume-based particle size distribution integral value of 50% (D50) of 50 nm or more and 350 nm or less. The volume-based particle size distribution integral value of 50% (D50) can be measured using a particle size distribution analyzer (apparatus name: BI-DCP Particle Size Analyzer, manufacturer: Brookhaven Instruments) according to a procedure in accordance with JIS K6217-6.

[0042] The content of amorphous carbon contained in the negative electrode composite layer 22 is preferably in the range of 25% by mass or more and 90% by mass or less, more preferably 30% by mass or more and 80% by mass or less, and even more preferably 35% by mass or more and 75% by mass or less, when the content of the negative electrode active material (in this embodiment, the total content of amorphous carbon and alloy-forming elements) is taken as 100% by mass. The amorphous carbon content in negative electrode mixture layer 22 can be measured, for example, by heating the negative electrode mixture layer to a high temperature of about 1000° C. in a flow of helium mixed with oxygen and quantifying the carbon dioxide generated. The alloy-forming element is preferably 10% by mass or more and 75% by mass or less, more preferably 20% by mass or more and 70% by mass or less, and even more preferably 25% by mass or more and 65% by mass or less, when the content of the negative electrode active material (in this embodiment, the total content of amorphous carbon and the first element) is 100% by mass.

[0043] 3. Method for manufacturing a solid secondary battery according to this embodiment Next, a description will be given of a method for manufacturing the solid secondary battery 1 according to this embodiment. The solid secondary battery 1 according to this embodiment can be manufactured by, for example, manufacturing the positive electrode layer 10, the negative electrode layer 20, and the solid electrolyte layer 30, respectively, and then laminating the above-mentioned layers by the following method.

[0044] (3-1. Positive electrode layer manufacturing process) First, a slurry (the slurry may be a paste, and the same applies to other slurries) is prepared by adding the cathode composite (cathode active material, binder, etc.) that constitutes the cathode composite layer 12 to a non-polar solvent. Next, the obtained slurry is applied to the cathode current collector 11 and dried. Next, the obtained laminate is pressed (for example, pressed using hydrostatic pressure) to prepare the cathode layer 10. The pressing step may be omitted. The cathode layer 10 may be prepared by compacting the cathode composite into a pellet shape or by stretching it into a sheet shape. When preparing the cathode layer 10 by these methods, the cathode current collector 11 may be pressure-bonded to the prepared pellet or sheet.

[0045] (3-2. Negative electrode layer manufacturing process) First, a slurry is prepared by adding the negative electrode composite material (amorphous carbon, first element, etc.) that constitutes the negative electrode composite layer 22 to a polar solvent or a non-polar solvent. Then, the obtained slurry is applied onto the negative electrode current collector 21 and dried. At this time, the mass of the negative electrode composite material layer 22 formed on the negative electrode current collector after drying is 1 cm 2 It is preferable to apply the coating so that the amount is in the range of 0.3 mg to 2 mg per unit area. Next, the obtained laminate is pressed (for example, pressed using hydrostatic pressure) to produce the negative electrode layer 20. The pressing step may be omitted. In addition, 1 cm of the negative electrode mixture layer 22 2 The mass per unit area can be measured by punching out a predetermined area of ​​the negative electrode active material layer on the current collector, measuring the mass, and subtracting the mass of the current collector from the obtained mass.

[0046] (3-3. Solid electrolyte layer manufacturing process) The solid electrolyte layer 30 can be made of a solid electrolyte formed from, for example, a sulfide-based solid electrolyte material.

[0047] First, the starting material is treated by melt quenching or mechanical milling.

[0048] For example, when using the melt quenching method, a sulfide-based solid electrolyte material can be produced by mixing predetermined amounts of starting materials (e.g., Li2S, P2S5, etc.), forming them into pellets, reacting them in a vacuum at a predetermined reaction temperature, and then quenching them. The reaction temperature for the Li2S and P2S5 mixture is preferably 400°C to 1000°C, more preferably 800°C to 900°C. The reaction time is preferably 0.1 hours to 12 hours, more preferably 1 hour to 12 hours. The quenching temperature for the reaction product is usually 10°C or lower, preferably 0°C or lower, and the quenching rate is usually about 1°C / sec to 10,000°C / sec, preferably about 1°C / sec to 1000°C / sec.

[0049] Furthermore, when mechanical milling is used, a sulfide-based solid electrolyte material can be produced by stirring and reacting starting materials (e.g., Li2S, P2S5, etc.) using a ball mill or the like. The stirring speed and stirring time in mechanical milling are not particularly limited, but the faster the stirring speed, the faster the rate at which the sulfide-based solid electrolyte material is produced, and the longer the stirring time, the higher the conversion rate of the raw materials to the sulfide-based solid electrolyte material.

[0050] The mixed raw material obtained by melt quenching or mechanical milling is then heat-treated at a predetermined temperature and pulverized to produce a particulate solid electrolyte. If the solid electrolyte has a glass transition temperature, the heat treatment may change it from amorphous to crystalline.

[0051] Subsequently, the solid electrolyte obtained by the above method can be formed into a film using a known film formation method such as aerosol deposition, cold spray, or sputtering, to produce the solid electrolyte layer 30. The solid electrolyte layer 30 may also be formed by pressurizing solid electrolyte particles alone. Alternatively, the solid electrolyte layer 30 may be formed by mixing the solid electrolyte with a solvent and a binder, applying, drying, and pressurizing the mixture.

[0052] (3-4. Assembly process of solid secondary batteries) The positive electrode layer 10, the negative electrode layer 20, and the solid electrolyte layer 30 produced by the above-described method are stacked so that the solid electrolyte layer 30 is sandwiched between the positive electrode layer 10 and the negative electrode layer 20, and pressurized (for example, by applying pressure using hydrostatic pressure), thereby producing the solid secondary battery 1 according to this embodiment. <4. Charging method for solid-state secondary batteries>

[0053] When the solid secondary battery 1 produced by the above method is operated, pressure may be applied to the solid secondary battery.

[0054] The pressure may be, for example, 0.01 MPa or more and 10 MPa or less, preferably 0.01 MPa or more and 1 MPa or less, and more preferably 0.05 MPa or more and 0.3 MPa or less. Pressure may also be applied by sandwiching the solid secondary battery 1 between two hard plates such as stainless steel, brass, aluminum, or glass, and fastening the two plates together with a screw. Furthermore, the temperature at which the solid secondary battery 1 according to this embodiment is operated is not particularly limited, but is preferably 15°C or higher and 70°C or lower, more preferably 15°C or higher and 50°C or lower, and is particularly preferably operated at room temperature, such as 20°C or higher and 30°C or lower.

[0055] In this embodiment, solid secondary battery 1 is charged beyond the charge capacity of negative electrode mixture layer 22. That is, negative electrode mixture layer 22 is overcharged. The charge amount is preferably between 2 and 100 times the charge capacity of negative electrode mixture layer 22, more preferably between 4 and 100 times. At the beginning of charging, lithium is absorbed into negative electrode mixture layer 22. That is, the negative electrode active material forms an alloy or a compound with lithium ions that have migrated from positive electrode layer 10. When further charging is performed beyond the capacity of negative electrode mixture layer 22, as shown in FIG. 2, lithium precipitates on the back side of negative electrode mixture layer 22, i.e., between negative electrode current collector 21 and negative electrode mixture layer 22, and this lithium forms metal layer 23. A solid secondary battery in which lithium precipitates on the negative electrode during charging to form metal layer 23 is called a precipitation-type solid secondary battery. The metal layer 23 may be formed inside the negative electrode mixture layer 22, for example, as shown in FIG. 3 . In other words, the metal layer 23 may be formed so as to be sandwiched between two split negative electrode mixture layers 22. The metal layer 23 is mainly composed of lithium (i.e., metallic lithium). This phenomenon occurs when a specific substance, i.e., an element that forms an alloy or compound with lithium, is used as the negative electrode active material. During discharge, lithium in the negative electrode mixture layer 22 and the metal layer 23 ionizes and migrates toward the positive electrode layer 10. Therefore, lithium can be used as the negative electrode active material in the solid secondary battery 1. Furthermore, since the negative electrode mixture layer 22 covers the metal layer 23, it functions as a protective layer for the metal layer 23 and can suppress the precipitation and growth of dendrites. This suppresses short circuits and capacity reduction in the solid secondary battery 1, thereby improving the characteristics of the solid secondary battery 1.

[0056] In the above-described precipitation-type solid secondary battery, it is preferable that the ratio of the charge capacity of positive electrode mixture layer 12 to the charge capacity of negative electrode mixture layer 22, i.e., the capacity ratio, satisfies the requirement of the following mathematical formula (1): 0.01 a: Charging capacity (mAh) of positive electrode composite layer 12 b: Charging capacity (mAh) of negative electrode composite layer 22 If the capacity ratio is 0.01 or more, the thickness of the negative electrode composite layer 22 can be sufficiently ensured, and the negative electrode composite layer 22 can easily function as a protective layer for the metal layer, thereby maintaining high performance of the solid secondary battery 1. Furthermore, if the capacity ratio is 0.5 or less, the amount of lithium deposited in the negative electrode can be sufficiently ensured, and a decrease in battery capacity can be suppressed. For the same reason, it is considered more preferable that the capacity ratio be less than 0.25. Furthermore, if the capacity ratio is less than 0.25, the output performance of the battery can be further improved.

[0057] ​Here, the charge capacity of the positive electrode mixture layer 12 is obtained by multiplying the charge capacity density (mAh / g) of the positive electrode active material by the mass of the positive electrode active material in the positive electrode mixture layer 12. When multiple types of positive electrode active materials are used, the value of charge capacity density x mass is calculated for each positive electrode active material, and the sum of these values ​​is taken as the charge capacity of the positive electrode mixture layer 12. The charge capacity of the negative electrode mixture layer 22 is also calculated in a similar manner. That is, the charge capacity of the negative electrode mixture layer 22 is obtained by multiplying the charge capacity density (mAh / g) of the negative electrode active material by the mass of the negative electrode active material in the negative electrode mixture layer 22. When multiple types of negative electrode active materials are used, the value of charge capacity density x mass is calculated for each negative electrode active material, and the sum of these values ​​is taken as the capacity of the negative electrode mixture layer 22. Here, the charge capacity densities of the positive electrode and negative electrode active materials are capacities estimated using an all-solid-state half cell using lithium metal as the counter electrode. In practice, the charge capacities of positive electrode mixture layer 12 and negative electrode mixture layer 22 are directly measured by measurement using an all-solid-state half cell.

[0058] Specific methods for directly measuring the charge capacity include the following. First, the charge capacity of the positive electrode composite layer 12 is measured by fabricating a test cell using the positive electrode composite layer 12 as the working electrode and Li as the counter electrode, and performing CC-CV charging from the open circuit voltage (OCV) to an upper charge voltage. The upper charge voltage is defined in JIS C 8712:2015, and refers to 4.25 V for lithium cobalt oxide-based positive electrodes, and the voltage determined by applying the provisions of A.3.2.3 (Safety requirements when a different upper charge voltage is applied) of JIS C 8712:2015 for other positive electrodes. The charge capacity of the negative electrode composite layer 22 is measured by fabricating a test cell using the negative electrode composite layer 22 as the working electrode and Li as the counter electrode, and performing CC-CV charging from the open circuit voltage (OCV) to 0.01 V.

[0059] The test cell described above can be fabricated, for example, by the following method. The positive electrode composite layer 12 or the negative electrode composite layer 22 for which the charge capacity is to be measured is punched out into a disk shape with a diameter of 13 mm. 200 g of the same solid electrolyte powder used in the solid secondary battery 1 is compacted at 40 MPa to form a pellet with a diameter of 13 mm and a thickness of approximately 1 mm. This pellet is placed inside a cylinder with an inner diameter of 13 mm, and the punched-out disk-shaped positive electrode composite layer 12 or the negative electrode composite layer 22 is placed on one side, and lithium foil with a diameter of 13 mm and a thickness of 0.03 mm is placed on the other side. Two stainless steel disks are then placed on each side, and the entire structure is pressurized in the axial direction of the cylinder at 300 MPa for one minute to integrate the contents. The integrated contents are then removed from the cylinder and sealed in a case under a constant pressure of 22 MPa to form a test cell. The charge capacity of positive electrode mixture layer 12 can be measured by CC charging the test cell prepared as described above at a current density of, for example, 0.1 mA, and then CV charging it down to 0.02 mA.

[0060] The charge capacity density is calculated by dividing this charge capacity by the mass of each active material. The initial charge capacities of positive electrode mixture layer 12 and negative electrode mixture layer 22 may be the initial charge capacities measured during the first charge cycle. This value was used in the examples described below.

[0061] <5. Effects of this embodiment> According to the solid secondary battery 1 configured as described above, the FWHM of the amorphous carbon contained in the negative electrode mixture layer 22 is 002 Since the amount of oxygen contained is within a predetermined range, the output characteristics can be significantly improved even when a precipitation-type solid secondary battery in which lithium is precipitated in layers by overcharging negative electrode composite layer 22 is charged and discharged under room temperature and low external pressure conditions. Furthermore, by setting the BET specific surface area and oil absorption of the amorphous carbon within predetermined ranges, the output characteristics of the precipitation-type solid secondary battery can be further improved.

[0062] In the solid secondary battery 1 according to this embodiment, the metal layer 23 is not formed in advance before the first charge, and therefore, as will be described later, the manufacturing cost can be further reduced compared to the solid secondary battery 1 according to the second embodiment of the present invention in which the metal layer 23 is formed in advance.

[0063] <6. Other embodiments of the present invention> <6-1. Configuration of the solid secondary battery according to the second embodiment of the present invention> Next, the configuration of a solid secondary battery 1a according to the second embodiment will be described with reference to Fig. 4. As shown in Fig. 4, the solid secondary battery 1a includes a positive electrode layer 10, a negative electrode layer 20, and a solid electrolyte layer 30. The configurations of the positive electrode layer 10 and the solid electrolyte layer 30 are the same as those of the first embodiment.

[0064] (Configuration of negative electrode layer) Negative electrode layer 20 includes negative electrode current collector 21, negative electrode composite material layer 22, and metal layer 23. That is, in the first embodiment, metal layer 23 that does not exist before the first charge is formed between negative electrode current collector 21 and negative electrode composite material layer 22 by overcharging negative electrode composite material layer 22. In contrast, in the second embodiment, as shown in FIG. 4 , this metal layer 23′ is formed in advance (i.e., before the first charge) between negative electrode current collector 21 and negative electrode composite material layer 22.

[0065] The configurations of the negative electrode current collector 21 and the negative electrode composite layer 22 are the same as those in the first embodiment. The metal layers 23 and 23′ contain lithium or a lithium alloy. That is, the metal layers 23 and 23′ function as lithium reservoirs. The lithium alloy may be, for example, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, or a Li-Si alloy. The metal layers 23 and 23′ may be composed of one of these alloys or lithium, or may be composed of multiple types of alloys. In the second embodiment, the metal layers 23 and 23′ function as lithium reservoirs, further improving the characteristics of the solid secondary battery 1.

[0066] Here, the thickness of the metal layer 23' is not particularly limited, but is preferably 1 μm or more and 200 μm or less. If the thickness of the metal layer 23' is less than 1 μm, the reservoir function of the metal layer 23' may not be fully exhibited. If the thickness of the metal layer 23' exceeds 200 μm, the mass and volume of the solid secondary battery 1 may increase, and the characteristics may actually deteriorate. For these reasons, the metal layer 23' is made of, for example, a metal foil having the above thickness.

[0067] <6-2. Method for manufacturing a solid secondary battery according to a second embodiment of the present invention> Next, a method for manufacturing the solid secondary battery 1 according to the second embodiment will be described. The positive electrode layer 10 and the solid electrolyte layer 30 are manufactured by the same method as in the first embodiment.

[0068] (Negative electrode layer manufacturing process) In the second embodiment, a negative electrode composite layer 22 is disposed on a metal layer 23′. The metal layer 23′ is often substantially a metal foil. Because it is difficult to form a negative electrode composite layer 22 on a lithium foil or a lithium alloy foil, the negative electrode layer 20 may be fabricated by the following method.

[0069] First, negative electrode composite layer 22 is formed on a substrate (e.g., a Ni plate) by the same method as in the first embodiment. Specifically, materials constituting negative electrode composite layer 22 are added to a solvent to prepare a slurry. Next, the obtained slurry is applied to the substrate and dried. Next, the obtained laminate is pressed (e.g., pressed using hydrostatic pressure) to form negative electrode composite layer 22 on the substrate. The pressing step may be omitted.

[0070] Next, solid electrolyte layer 30 is laminated on negative electrode composite layer 22, and the resulting laminate is pressurized (for example, pressurized using hydrostatic pressure). Next, the base material is removed. In this way, a laminate of negative electrode composite layer 22 and solid electrolyte layer 30 is produced.

[0071] Next, the metal foil constituting metal layer 23′, a laminate of negative electrode composite layer 22 and solid electrolyte layer 30, and positive electrode layer 10 are sequentially laminated on negative electrode current collector 21. Next, the obtained laminate is pressed (for example, by pressing using hydrostatic pressure) to produce solid secondary battery 1a.

[0072] When the solid-state battery produced by the above method is operated, the operation may be performed in a state where pressure is applied to the solid-state battery.

[0073] The pressure may be 0.5 MPa or more and 10 MPa or less. Alternatively, the pressure may be applied by sandwiching the solid secondary battery 1a between two hard plates made of stainless steel, brass, aluminum, glass, or the like, and fastening the two plates together with a screw.

[0074] <6-3. Charging Method for Solid-State Secondary Battery According to Second Embodiment of the Present Invention> The method of charging the solid secondary battery 1a according to this embodiment is the same as that according to the first embodiment. That is, the solid secondary battery 1a is charged beyond the charge capacity of the negative electrode mixture layer 22. That is, the negative electrode mixture layer 22 is overcharged. At the beginning of charging, lithium is absorbed in the negative electrode mixture layer 22. When charging is performed beyond the capacity of the negative electrode mixture layer 22, lithium is precipitated in the metal layer 23′ (or on the metal layer 23′). During discharge, the lithium in the negative electrode mixture layer 22 and the metal layer 23′ (or on the metal layer 23) is ionized and moves toward the positive electrode layer 10. Thus, in the solid secondary battery 1a according to the second embodiment, lithium is also precipitated in the negative electrode layer during charging, so this solid secondary battery 1a can also be said to be a precipitation-type solid secondary battery. As in the first embodiment described above, a metal layer 23 may be further formed inside negative electrode mixture layer 22 by the deposited lithium.

[0075] 6-4. Effects of the second embodiment of the present invention The solid secondary battery 1a configured in this manner can also significantly improve the output characteristics of a precipitation-type solid secondary battery, even when charged and discharged under room temperature and low external pressure conditions, as in the above-described embodiment. Furthermore, the negative electrode composite layer 22 covers the metal layer 23', and therefore functions as a protective layer for the metal layer 23' and can suppress the precipitation and growth of dendrites. This suppresses short circuits and capacity reduction in the solid secondary battery 1a, thereby improving the characteristics of the solid secondary battery 1a.

[0076] <6-5. Third embodiment of the present invention>

[0077] Here, as shown in FIG. 5, a thin film 24 may be formed on the surface of the negative electrode current collector 21. The thin film 24 contains an element capable of forming an alloy with lithium. Examples of such elements include gold, silver, zinc, tin, indium, silicon, aluminum, and bismuth. The thin film 24 may be composed of any one of these metals, or may be composed of an alloy of multiple types of these metals. The presence of the thin film 24 makes the deposition morphology of the metal layer 23 flatter, further improving the characteristics of the solid secondary battery 1.

[0078] Here, the thickness of the thin film 24 is not particularly limited, but is preferably 1 nm or more and 500 nm or less. If the thickness of the thin film 24 is less than 1 nm, the thin film 24 may not be able to fully exhibit its functions. If the thickness of the thin film 24 exceeds 500 nm, the amount of lithium deposited on the negative electrode may decrease due to lithium absorption in the thin film 24 itself, which may actually deteriorate the characteristics of the solid secondary battery 1. The thin film 24 is formed on the negative electrode current collector 21 by, for example, vacuum deposition, sputtering, or plating.

[0079] <6-6. Other embodiments of the present invention> In the first to third embodiments, the solid secondary battery is described as an all-solid secondary battery, but the negative electrode material for a secondary battery and the negative electrode layer for a secondary battery according to the present invention can be applied to any solid secondary battery that includes a solid negative electrode layer and a solid solid electrolyte layer. For example, they can also be applied to solid secondary batteries in which part or all of the positive electrode layer is not solid, and solid secondary batteries that contain an electrolytic solution in addition to a solid electrolyte. Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications and alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention. [Example]

[0080] The negative electrode composite, the negative electrode composite layer formed from this negative electrode composite, and the solid secondary battery including this negative electrode composite layer according to the present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0081] (1. Description of Examples and Comparative Examples) Example 1 In this example, amorphous carbon and an alloying element were used as the negative electrode active material, and a negative electrode mixture for a solid secondary battery was prepared by the following method. (1-1. Preparation of negative electrode layer) In this example, amorphous carbon and an alloying element were used as the negative electrode active material, and the negative electrode layer was produced by the following method. Silver particles (manufactured by DOWA Electronics) with a particle size of approximately 60 nm were used as the alloying element. Amorphous carbon A (oxygen content 0.95 at%, FWHM002 = 5.1), a carbon black whose properties are shown in Table 1, was used as the amorphous carbon. First, 12 g of amorphous carbon A and 4 g of silver particles were placed in a container, and 14 g of an NMP solution containing 8 wt% of a binder (PVDF) was added thereto. 16 g of zirconia beads (φ2 mm) were added, and a total of 55 g of NMP was added and stirred to prepare a slurry. This slurry was applied to a current collector with 10 micron-thick Cu foil plated with 1 micron-thick Ni using a blade coater, dried in air at 80 ° C for about 20 minutes, and then vacuum dried at 100 ° C for about 12 hours to form a negative electrode composite layer. In this example, the negative electrode composite layer after formation was 1 cm 2 Although the coating amount is set to 1.0 mg per coating, the same effect can be obtained even if the coating amount is changed in various ways within the range of 0.3 mg to 2 mg.

[0082] (1-2. Preparation of the positive electrode layer) LiNi coated with Li2O-ZrO2 as the positive electrode active material 0.8 Co 0.15 Al 0.05 The positive electrode layer was prepared using O2(NCA) in the following manner. The solid electrolyte was Li6PS5Cl, an argyrodite-type crystal. The solid electrolyte, conductive agent (carbon nanotubes (CNTs)), and binder (polytetrafluoroethylene (PTFE)) were mixed in a mass ratio of 85:14.45:0.25:0.30 (positive electrode active material: solid electrolyte: CNT: PTFE), and the mixture was stretched into a sheet to form the positive electrode composite. This positive electrode composite layer sheet was then formed into a 2 cm square and pressure-bonded to an 18 μm thick aluminum foil positive electrode current collector to form the positive electrode layer.

[0083] (1-3. Creation of solid electrolyte layer) To 100 parts by mass of the Li6PS5Cl solid electrolyte, 2 parts by mass of an acrylic binder was added, and the mixture was stirred while adding xylene to prepare a slurry. This slurry was then applied to a PET film using a blade coater, dried in air at 40°C, and then vacuum-dried at 40°C for 12 hours to prepare a solid electrolyte layer.

[0084] (1-4. Fabrication of all-solid-state secondary batteries) The positive electrode layer, solid electrolyte layer, and negative electrode layer prepared by the above method were stacked in this order and sealed in a laminate film in a vacuum to produce an all-solid-state secondary battery. A portion of each of the positive electrode layer and the negative electrode layer was exposed from the laminate film so as not to break the vacuum of the all-solid-state secondary battery, and these exposed portions served as the terminals of the positive electrode layer and the negative electrode layer, respectively. This all-solid-state secondary battery was subjected to hydrostatic pressure treatment at 490 MPa for 30 minutes, completing the manufacturing process of the all-solid-state secondary battery.

[0085] (1-5. Evaluation of all-solid-state secondary batteries) The charge / discharge characteristics of the all-solid-state secondary battery thus fabricated were evaluated under the following conditions. First, the all-solid-state secondary battery was sandwiched between two metal plates and the screws were tightened with a torque to apply an external pressure of 0.3 MPa to the all-solid-state secondary battery. The measurement was also carried out by placing the all-solid-state secondary battery in a thermostatic chamber at 25°C. In the first cycle, the current was 0.45 mA / cm until the battery voltage reached 4.25 V. 2 The battery was charged at a constant current of 0.5 mA / cm until the current reached 0.2 mA, and then at a constant voltage of 4.25 V until the battery voltage reached 2.5 V. 2 In the second and third cycles, the battery was charged under the same conditions as in the first cycle, with a constant current of 1.48 mA / cm. 2 , 4.5mA / cm 2 The battery was discharged at a constant current of 1000 kJ / 2000 kJ / 1000 kJ / 2000 kJ until the battery voltage reached 2.5 V. As shown in Table 1, the ratio of the capacity in the third cycle to the capacity in the first cycle was 81.0%.

[0086] <Examples 2 to 13, Comparative Examples 1 and 2> All-solid-state secondary batteries were fabricated in the same manner as in Example 1, except that each amorphous carbon shown in Table 1 was used and the ratio of amorphous carbon to alloying elements was set as shown in Table 1, and the same evaluations were carried out as in Example 1. The results are shown in Table 1.

[0087] [Table 1] In addition, for amorphous carbons I and K in Table 1, the oil absorption could not be measured due to their high lipophilicity, but since the oil absorption of the amorphous carbons that served as raw materials before oxidation treatment was approximately 180, the oil absorption of amorphous carbons I and K is estimated to be approximately 180.

[0088] (2. Consideration) From the results of Examples 1 to 13 and Comparative Examples 1 and 2, it was found that the amorphous carbon used in the negative electrode composite for the all-solid-state secondary battery had a FWHM 002 When the amorphous carbon content is 25% by mass or more and 90% by mass or less, where the total mass of the amorphous carbon and the alloying elements is 100% by mass, and the angle is 4° or more and 6° or less, and the oxygen content is 0.5 at% or more and 10 at% or less, the third cycle capacity / first cycle capacity of the all-solid-state secondary battery can be made high enough to withstand practical use, even under room temperature and low external pressure conditions. Note that when the all-solid-state secondary batteries of Example 3 and Comparative Example 1 were evaluated at 60°C and 4 MPa, it was confirmed that the third cycle capacity / first cycle capacity was both high, at 80% or more. Furthermore, as can be seen from the results in Table 1, it was found that a lower oxygen content of the amorphous carbon tends to increase the battery output under room temperature and low external pressure conditions. Since the upper limit of the oxygen content of carbon black that can be produced with current technology is 10, in this embodiment the upper limit of the preferred range is provisionally set to 10, but if carbon black with a higher value can be produced, a larger value may be acceptable. [Explanation of symbols]

[0089] 1, 1a all-solid-state secondary battery 10 Positive electrode layer 11 Positive electrode current collector 12 Positive electrode mixture layer 20 negative electrode layer 21 Negative electrode current collector 22 Negative electrode composite layer 23 Metal layer 24 Thin Film 30 Solid electrolyte layer

Claims

1. The battery contains amorphous carbon, an alloying element that forms an alloy with lithium through an electrochemical reaction, and a binder, the content of the amorphous carbon is 25% by mass or more and 90% by mass or less when the total mass of the amorphous carbon and the alloying element is 100% by mass, The full width at half maximum (FWHM) of the (002) peak of the carbon measured by X-ray diffraction measurement using Cu-Kα rays of the amorphous carbon ００２ ) is 4° or more and 6° or less, The negative electrode composite for a precipitation-type solid secondary battery has an oxygen content of 0.5 at % or more and 10 at % or less, where the entire amorphous carbon is taken as 100 at %.

2. The amorphous carbon has a BET specific surface area of ​​10 m2 or less, calculated from an adsorption isotherm measured by adsorbing nitrogen onto the amorphous carbon. ２ / g or more 180m ２ The negative electrode mixture for a precipitation-type solid secondary battery according to claim 1, wherein the SiO2 content is 0.15 / g or less.

3. 2. The negative electrode mixture for a precipitation-type solid secondary battery according to claim 1, wherein the amorphous carbon has an oil absorption of 60 ml / 100 g or more and 400 ml / 100 g or less.

4. 2. The negative electrode mixture for a precipitation-type solid secondary battery according to claim 1, wherein the amorphous carbon has a volume-based particle size distribution integrated value of 50% (D50) of 50 nm or more and 350 nm or less.

5. 2. The negative electrode mixture for a precipitation-type solid secondary battery according to claim 1, wherein the alloying element is at least one selected from the group consisting of gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, indium, and zinc.

6. 2. The negative electrode mixture for a deposition-type solid secondary battery according to claim 1, wherein the amorphous carbon is carbon black.

7. a negative electrode current collector; and a negative electrode mixture layer laminated on the negative electrode current collector, The negative electrode mixture layer for a precipitation-type solid secondary battery, comprising the negative electrode mixture according to any one of claims 1 to 6.

8. 1 cm of the negative electrode mixture layer ２ The negative electrode layer for a deposition-type solid secondary battery according to claim 7 , wherein the mass per unit area is 0.3 mg or more and 2 mg or less.

9. The negative electrode layer for a deposition-type solid secondary battery according to claim 7 , wherein the negative electrode mixture layer does not contain a solid electrolyte.

10. A solid secondary battery comprising a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, A precipitation-type solid secondary battery, wherein the negative electrode layer is the one described in claim 7.

11. the positive electrode layer comprises a positive electrode mixture layer, The precipitation-type solid secondary battery according to claim 10 , wherein a ratio of an initial charge capacity of the positive electrode mixture layer to an initial charge capacity of the negative electrode mixture layer satisfies the requirement of the following mathematical formula (1): 0.01<b / a<0.5 (1) a: initial charge capacity of the positive electrode composite layer (mAh) b: Initial charge capacity of the negative electrode composite layer (mAh)

12. A method for charging a precipitation-type solid state secondary battery, comprising charging the precipitation-type solid state secondary battery according to claim 10 beyond an initial charge capacity of the negative electrode mixture layer.

13. The method for charging a precipitation-type solid secondary battery according to claim 12, wherein the negative electrode mixture layer is charged to a charge capacity that is 2 to 100 times the initial charge capacity.

14. A method for using a precipitation-type solid state secondary battery, comprising sandwiching the precipitation-type solid state secondary battery according to claim 10 between two plates and charging and discharging the battery while applying pressure thereto.

15. The method for using a precipitation-type solid secondary battery according to claim 14, wherein the pressure is 0.1 MPa or more and 1 MPa or less.

16. A method for using the precipitation-type solid state secondary battery according to claim 14, comprising charging and discharging the precipitation-type solid state secondary battery according to claim 10 at a temperature of 20°C or higher and 30°C or lower.

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