Negative electrode composite material for precipitation-type solid secondary battery, negative electrode layer for precipitation-type solid secondary battery, precipitation-type solid secondary battery, and charging method thereof

Abstract

Even when charging and discharging under room temperature and low pressure conditions, the output characteristics of a precipitation-type solid secondary battery can be greatly improved. This negative electrode composite material for a precipitation-type solid secondary battery comprises: amorphous carbon; an alloy-forming element forming an alloy with lithium by an electrochemical reaction; and a binder, wherein when the total mass of the amorphous carbon and the alloy-forming element is 100 mass%, the content of the amorphous carbon is 25 mass% or more and 90 mass% or less, the full width at half maximum (FWHM002) of a (002) peak of carbon, obtained by X-ray diffraction measurement of the amorphous carbon using a Cu-Kα line, is 4° or more and 6° or less, and the oxygen content of the amorphous carbon is 0.5 at% or more and 10 at% or less.

Description

Anode composite material for a precipitation-type solid secondary battery, anode layer for a precipitation-type solid secondary battery, precipitation-type solid secondary battery, and charging method thereof

[0001] The present invention relates to a negative electrode composite material 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.

[0002] An all-solid-state secondary battery using lithium as an active material, which is deposited on a cathode layer during charging, has been disclosed in the prior art. The cathode composite material of this precipitation-type all-solid-state secondary battery contains carbon black. The prior art discloses the manufacture of an all-solid-state secondary battery that operates well under conditions of 60°C and 4 MPa by using the carbon black's nitrogen adsorption specific surface area and DBP oiling quantity within a predetermined range.

[0003] The present invention aims to enable a precipitation-type solid-state secondary battery to operate well under room temperature and low pressure conditions, rather than the aforementioned high temperature and high pressure conditions. The goal is to identify a negative electrode composite material that can significantly improve the output characteristics of a precipitation-type solid-state secondary battery even when charged and discharged under room temperature and low pressure conditions.

[0004] In other words, the negative electrode composite material 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 affecting the present invention are as follows.

[0005] According to one embodiment of the present invention, a negative electrode composite material for a precipitation-type solid secondary battery is provided. The negative electrode composite material for a precipitation-type solid secondary battery contains amorphous carbon, an alloy-forming element that forms an alloy with lithium by an electrochemical reaction, and a binder, and when the total mass of the amorphous carbon and the alloy-forming element is 100 mass%, the content of the amorphous carbon is 25 mass% or more and 90 mass% or less, and the full width at half maximum (FWHM) of the (002) peak of the carbon obtained by X-ray diffraction measurement using Cu-Kα lines of the amorphous carbon 002 ) is 4° or more and 6° or less, and when the total amorphous carbon is 100 at%, the oxygen content of the amorphous carbon may be 0.5 at% or more and 10 at% or less.

[0006] The BET specific surface area calculated by the adsorption isotherm measured by adsorbing nitrogen on the above amorphous carbon is 10 m 2 / g or more 180m 2 / g can be less.

[0007] The oil absorption capacity of the above amorphous carbon may be 60 ml / 100 g or more and 400 ml / 100 g or less.

[0008] The cumulative value of the volume-based particle size distribution of the above amorphous carbon may be 50% (D50) or more and 350 nm or less.

[0009] The above alloy forming element may be at least one selected from the group consisting of gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, indium and zinc. In claim 1,

[0010] The above amorphous carbon may be carbon black.

[0011] According to one embodiment of the present invention, a negative electrode layer for a precipitation-type solid-state secondary battery is provided. The negative electrode for a precipitation-type solid-state secondary battery comprises a negative electrode current collector and a negative electrode composite material layer laminated on the negative electrode current collector, wherein the negative electrode composite material layer may include the above-described negative electrode composite material.

[0012] 1 cm of the above negative composite material layer 2 The mass of the sugar may be 0.3 mg or more and 2 mg or less.

[0013] The above negative composite material layer may not include a solid electrolyte.

[0014] According to one embodiment of the present invention, a precipitation-type solid-state secondary battery is provided. The precipitation-type solid-state secondary battery is a solid-state secondary battery having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein the negative electrode layer may be as described above.

[0015] According to one embodiment of the present invention, a precipitation-type solid-state secondary battery is provided. The precipitation-type solid-state secondary battery includes a negative electrode composite material layer having the above-described negative electrode composite material for a precipitation-type solid-state secondary battery, and a positive electrode composite material layer, wherein a ratio of the initial charge capacity of the positive electrode composite material layer to the initial charge capacity of the negative electrode composite material layer can satisfy the requirements of the following equation.

[0016] 0.01

[0017] a: Initial charge capacity (mAh) of the positive electrode composite layer

[0018] b: Initial charge capacity (mA) of the negative composite layer

[0019] According to one embodiment of the present invention, a method for charging a precipitation-type solid-state secondary battery is provided. The method for charging the precipitation-type solid-state secondary battery may be a method for charging the precipitation-type solid-state secondary battery beyond the initial charge capacity of the negative electrode composite material layer.

[0020] The above negative composite material layer can be charged up to a charging capacity of 2 to 100 times the initial charging capacity.

[0021] According to one embodiment of the present invention, a method of using a precipitation-type solid-state secondary battery is provided. The method may comprise sandwiching the precipitation-type solid-state secondary battery between two plates and charging and discharging the battery while applying pressure.​

[0022] The above pressure may be 0.1 MPa or more and 1 MPa or less.

[0023] The aforementioned precipitation-type solid-state secondary battery can be charged and discharged at a temperature of 20°C or higher and 30°C or lower.

[0024] According to the present invention, the output characteristics of a precipitation-type solid-state secondary battery can be significantly improved even when charging and discharging under conditions of room temperature and low pressure.

[0025] FIG. 1 is a cross-sectional view showing a schematic configuration of a solid secondary battery according to a first embodiment of the present invention.

[0026] FIG. 2 is a cross-sectional view schematically showing a configuration in which a lithium metal layer is precipitated in a solid secondary battery according to the first embodiment of the present invention.

[0027] FIG. 3 is a cross-sectional view schematically showing a configuration in which a lithium metal layer is precipitated in a solid secondary battery according to the first embodiment of the present invention.

[0028] Figure 4 is a cross-sectional view showing a schematic configuration of a solid secondary battery according to a second embodiment of the present invention.

[0029] Figure 5 is a cross-sectional view showing a schematic configuration of a solid secondary battery according to a third embodiment of the present invention.

[0030] Hereinafter, the best embodiments of the present invention will be described in detail with reference to the attached drawings. In the present specification and drawings, components having substantially the same functional configuration are designated by the same reference numerals, thereby omitting redundant descriptions.

[0031] <1. Basic configuration of a solid secondary battery according to the first embodiment of the present invention>

[0032] A solid secondary battery (1) according to the first embodiment of the present invention may include, for example, a positive electrode layer (10), a negative electrode layer (20), and a solid electrolyte layer (30), as shown in FIG. 1.

[0033] (1-1. Bipolar layer)

[0034] The positive electrode layer (10) may include a positive electrode current collector (11) and a positive electrode composite material layer (12).

[0035] The positive electrode current collector (11) may be composed of, for example, 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 have a plate shape or a foil shape. The positive electrode current collector (11) may be omitted.

[0036] The positive electrode composite material layer (12) may include a positive electrode active material and a solid electrolyte. Meanwhile, the solid electrolyte contained in the positive electrode layer (10) may be the same as the solid electrolyte contained in the solid electrolyte layer (30). Details of the solid electrolyte are described in detail in the section on the solid electrolyte layer (30).

[0037] The cathode active material can reversibly absorb and desorb lithium ions.

[0038] The cathode active material may be formed of, for example, lithium cobalt oxide (hereinafter referred to as LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (hereinafter referred to as NCA), lithium nickel cobalt manganese oxide (hereinafter referred to as NCM), lithium manganese oxide, or a lithium salt such as lithium iron phosphate. Furthermore, the cathode active material may be formed of nickel sulfide, copper sulfide, lithium sulfide, sulfur, iron oxide, or vanadium oxide. These cathode active materials may be used alone, or may be formed by combining two or more types.

[0039] It is preferable that the cathode active material be formed by containing a lithium salt of a transition metal oxide having a layered rock salt structure. Here, the 'layered rock salt structure' means a cubic rock salt structure. <111> It is a structure in which oxygen atomic layers and metal atomic layers are arranged alternately and regularly in a direction, and as a result, each atomic layer forms a two-dimensional plane. In addition, the 'cubic rock salt structure' refers to the sodium chloride structure, which is one of the crystal structures, and specifically, it refers to a structure in which the face-centered cubic lattices formed by each of the cations and anions are arranged offset from each other by half of the ridge of the unit cell.

[0040] Lithium salts of transition metal oxides having this layered rock salt structure are, for example, LiNi x Co y Al z O2(NCA) or LiNi x Co y Mn z O2(NCM) (but, 0 <x <1, 0 <y <1, 0 <z <1, 그리고 x+y+z=1)과 같은 삼원계 전이 금속산화물의 리튬염을 포함할 수 있다.

[0041] When the positive electrode active material contains a lithium salt of a ternary transition metal oxide having the layered rock salt structure, the energy density and thermal stability of the all-solid-state secondary battery (1) can be improved.

[0042] The positive electrode active material may be covered by a coating layer. The coating layer of the first embodiment may be any known coating layer of the positive electrode active material of the all-solid-state secondary battery (1). The coating layer may be, for example, Li2-ZrO2.

[0043] Furthermore, when the positive electrode active material is formed of a lithium salt of a ternary transition metal oxide such as NCA or NCM and the positive electrode active material contains nickel, the coating layer can increase the capacity density of the all-solid-state secondary battery (1) and reduce metal elution into the positive electrode active material in a charged state. Accordingly, the solid-state secondary battery (1) according to the first embodiment can improve long-term reliability and cycle characteristics in a charged state.

[0044] Here, the positive electrode active material may have a particle shape, such as, for example, a true spherical shape or an elliptical spherical shape. In addition, the particle size of the positive electrode active material is not particularly limited, and may be within a range applicable to positive electrode active materials of conventional all-solid-state secondary batteries. Meanwhile, the content of the positive electrode active material in the positive electrode layer (10) is not particularly limited, and may be within a range applicable to positive electrode layers of conventional all-solid-state secondary batteries.

[0045] In addition, in addition to the above-described positive electrode active material and solid electrolyte, additives such as a conductive additive, a binder, a filler, a dispersant, or an ion conductive additive may be appropriately blended into the positive electrode active material layer (12).

[0046] The conductive agent that can be mixed into the positive electrode active material layer (12) may be, for example, graphite, carbon black, acetylene black, ketjen black, carbon fiber, or metal powder. In addition, the binder that can be mixed into the positive electrode active material layer (12) may be, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, or polyethylene. Furthermore, the filler, dispersant, and ion conductive agent that can be mixed into the positive electrode active material layer (12) may be any known material that can be generally used in the electrode of an all-solid-state secondary battery (1).

[0047] The positive electrode layer (10) may contain a liquid electrolyte. In this case, the positive electrode layer (10) may not contain a solid electrolyte. Any electrolyte usable in lithium ion batteries may be used. By containing the electrolyte in the positive electrode layer (10), ion conduction between positive electrode active material particles is facilitated, thereby improving output. In this way, when the positive electrode layer (10) contains the electrolyte, the infiltration of the electrolyte into the negative electrode side can be suppressed by the solid electrolyte layer (30).

[0048] (1-2. Cathode layer)

[0049] The negative electrode layer (20) may include a negative electrode current collector (21) and a negative electrode composite material layer (22). The negative electrode current collector (21) does not react with lithium. That is, the negative electrode layer (20) is preferably composed of a material that does not form both an alloy and a compound. The material constituting the negative electrode current collector (21) may be, for example, copper, stainless steel, titanium, iron, cobalt, or nickel. The negative electrode current collector (21) may be composed of any one of these metals, or may be composed of an alloy or a clad material of two or more metals. The negative electrode current collector (21) may have, for example, a plate shape or a foil shape.

[0050] The negative electrode composite material layer (22) includes a negative electrode active material. In the first embodiment, the negative electrode active material may include amorphous carbon or an alloy-forming element. The amorphous carbon is preferably carbon black. The carbon black may include acetylene black, furnace black, or ketjen black.

[0051] An alloy-forming element is an element that forms an alloy or compound with lithium through an electrochemical reaction, and specifically, may include one or more selected from the group consisting of gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, indium, and zinc.

[0052] The alloy-forming element is, for example, in the form of particles, and the 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) can be further improved. Here, the particle size of the negative active material can be measured, for example, by a median diameter (i.e., D50) using a laser particle size distribution meter, or by measuring the particle size with a scanning electron microscope (SEM) or a transmission electron microscope (TEM), and is a value calculated from the arithmetic mean diameter of 100 particles, for example. The examples and comparative examples described below measured the particle size by this method. The lower limit of the particle size is not particularly limited, but is preferably 10 nm.

[0053] It is preferable that the negative electrode composite material layer (22) further contain an element that does not form an alloy or compound with lithium as an additive.

[0054] The element that does not form an alloy or compound with lithium may be an element of the fourth period of the periodic table of elements, and may be an element belonging to groups 3 to 11. More specifically, the element that does not form an alloy or compound with lithium may include one or more selected from the group consisting of iron, copper, nickel, and titanium. The element is preferably in a granular form, and the preferred average primary particle size may vary depending on each element, but is preferably, for example, 65 nm or more and 800 nm or less. Meanwhile, the average primary particle size can be measured by a scanning electron microscope (SEM) or a transmission electron microscope (TEM), and may be calculated, for example, from the arithmetic mean diameter of 100 particles.

[0055] The negative composite material layer (22) may contain a binder (adhesive). The binder may be, for example, styrene butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, or polyethylene. The binder may be composed of one type thereof, or may be composed of two or more types thereof.

[0056] Since the negative electrode composite material layer (22) contains a binder, the negative electrode composite material layer (22) can be more stabilized by making it difficult to peel off from the negative electrode current collector (21). Further, as will be described in detail later, the negative electrode composite material layer (22) can be formed by applying a slurry in which the negative electrode composite material constituting the negative electrode composite material layer (22) is dispersed onto the negative electrode current collector (21) and drying it. Since the negative electrode composite material layer (22) contains a binder, the negative electrode active material can be stably dispersed within the aforementioned slurry.

[0057] Here, the binder content in the negative electrode composite material layer (22) is preferably 0.3 mass% or more and 15 mass% or less, when the total mass of the negative electrode active material is 100 mass%. When the binder content is 0.3 mass% or more, the strength of the negative electrode composite material layer (22) becomes sufficient, and a deterioration in characteristics can be suppressed. When the binder content is 20 mass% or less, a deterioration in characteristics of the solid secondary battery (1) can be suppressed. The preferable lower limit of the binder content is 1 mass%.

[0058] The negative electrode composite material layer (22) may appropriately contain additives used in conventional solid secondary batteries (e.g., fillers, dispersants, or ionic electrical conductors).

[0059] (1-3. Solid electrolyte layer)

[0060] The solid electrolyte layer (30) can be laminated between the positive electrode layer (10) and the negative electrode layer (20) and can include a solid electrolyte.

[0061] The solid electrolyte may be composed of, for example, a sulfide-based solid electrolyte and / or an oxide-based solid electrolyte. The sulfide-based solid electrolyte may be composed of, for example, Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element, for example, I, Br, Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-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, n are defined numbers, Z is any one of Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, or Li2S-SiS2-Li p MO q (p, q are integers, M can be any one of P, Si, Ge, B, Al, Ga or In). Here, the sulfide-based solid electrolyte can be formed by treating the starting material (e.g., Li2S, P2S5, etc.) by a melt-quenching method or mechanical milling. In addition, an additional heat treatment can be provided after this treatment. The sulfide-based solid electrolyte can be in an amorphous, crystalline, or mixed state thereof.

[0062] In addition, the solid electrolyte preferably contains sulfur (S), phosphorus (P), or lithium (Li) as at least one constituent element among the above-mentioned sulfide solid electrolytes, and more preferably contains Li2S-P2S5.

[0063] Here, when Li2S-P2S5 is used as the sulfide-based solid electrolyte forming the solid electrolyte, the mixing molar ratio of Li2S and P2S5 is preferably selected in the range of, for example, Li2S: P2S5 = 50:50 to 90:10. In addition, it is preferable that the solid electrolyte layer (30) further includes a binder. The binder may be, for example, styrene butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, or polyethylene. The binder in the solid electrolyte layer (30) may be the same as the binder contained in the positive electrode composite material layer (12) and the negative electrode composite material layer (22), but is not limited thereto and may be different.

[0064] The oxide-based solid electrolyte may be, for example, a garnet-type composite oxide, a perovskite-type oxide, a LISICON-type composite oxide, a NASICON-type composite oxide, a Li alumina-type composite oxide, LiPON, or an oxide glass. Among these oxide-based solid electrolytes, it is preferable to select an oxide-based solid electrolyte that is stable to 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 Al0. 69 Ti 1.46 (PO4)3, or Li 1.5 Al 10.5 Ge1.5 (PO4)3 is more preferable.

[0065] <2. Characteristic configuration of a solid secondary battery according to the first embodiment of the present invention>

[0066] However, in the amorphous carbon contained in the negative electrode composite material layer (22) of the solid secondary battery (1) according to the first embodiment of the present invention, the 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. FWHM of amorphous carbon 002 It is more preferable that it is 4.5° or more and 5.8° or less, and it is even more preferable that it is 4.7° or more and 5.5° or less. Meanwhile, FWHM 002 is an indicator of the crystallinity of amorphous carbon, and amorphous carbon in the range of 4° to 6° mentioned above is close to an amorphous state and has appropriate anisotropy.

[0067] FWHM 002 can be measured in the following way.

[0068] An X-ray diffraction measurement apparatus (Empyrean, manufactured by PANalytyca) was used, and X-ray diffraction measurements were performed on carbon powder. The source was Cu-Kα, and the acceleration voltage and current were 30 kV and 10 mA, respectively. Using X'Pert HighScore Plus, an accessory software of the X-ray diffraction measurement apparatus, the full width at half maximum for the diffraction peaks present at 2θ = 20-30° in the X-ray diffraction diagram was determined for the X-ray diffraction data obtained through the aforementioned X-ray diffraction measurements.

[0069] In the first embodiment, when the total amorphous carbon is 100 at%, the oxygen content of the amorphous carbon is 0.5 at% or more and 10 at% or less. The oxygen content of the amorphous carbon is more preferably 0.6 at% or more and 5 at% or less, and is even more preferably 0.7 at% or more and 4 at% or less. Meanwhile, the oxygen content of the amorphous carbon indicates the content of acidic functional groups possessed by the amorphous carbon, and this oxygen content can be controlled by conventional methods such as calcination treatment or acid treatment.

[0070] The oxygen content of amorphous carbon can be measured by the following method.

[0071] Measurements were performed on powder samples of amorphous carbon under the following conditions. From the peak of the measured O1s binding energy (529-536 eV), the oxygen content was calculated using the sensitivity coefficient recommended by the device manufacturer.

[0072] (Measurement conditions)

[0073] Device: Quantera SXM from PHI

[0074] X-ray source / X-ray output / analysis area: single crystal spectrophotometer Al Kα ray / 50.0W / Φ200㎛

[0075] Pass Energy: Wide Scan -280.00eV (1.00eV / Step),

[0076] Narrow Scan -69.00eV (0.125eV / Step)

[0077] Charge neutralization gun: Ar+, e-use

[0078] geometry: θ=45deg. (θ: angle between sample surface and detector)

[0079] The BET surface area of ​​amorphous carbon is 10 m 2 / g or more 180m 2 / g or less is preferable, and 15m 2 / g or more than 100m 2 / g or less is more desirable, and 15m 2 / g or more than 60m 2 / g or less is more desirable.

[0080] BET surface area of ​​amorphous carbon (m 2 / g) can be measured by the nitrogen adsorption method (multi-point method) (JIS K6217-2:2017). Specifically, amorphous carbon is degassed at high temperatures. For example, amorphous carbon such as carbon black is cooled to liquid nitrogen temperature under vacuum. Then, nitrogen gas is introduced and, after reaching equilibrium, the nitrogen atmospheric pressure and nitrogen adsorption amount are measured. These measurements are performed multiple times in the range of relative pressure (nitrogen atmospheric pressure / saturated vapor pressure) 0.05 to 0.35. The obtained values ​​of nitrogen atmospheric pressure and nitrogen adsorption amount are applied to the BET (Brunauer-Emmett-Teller) equation to obtain the single molecule adsorption amount (the volume of nitrogen gas adsorbed on the first layer of the sample surface). The value of the nitrogen adsorption specific surface area can be calculated from this single molecule adsorption amount and the sample mass.

[0081] Furthermore, the oil absorption amount 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.

[0082] The oil absorption of amorphous carbon can be calculated by measuring the oil absorption according to JIS K6217-4:2017. Specifically, oil (dibutyl phthalate (DBP) or paraffin oil) is titrated into a sample stirred by a rotor using a constant-speed burette. By adding oil, the mixture changes from a freely flowing powder to a somewhat viscous mass. The point at which the torque generated by the change in viscosity reaches a set value or a certain percentage of the maximum torque obtainable from the torque curve is called the end point of this measurement. The oil absorption (ml / 100g) can be obtained by dividing the volume of oil (ml) at the end point by the sample mass (g) and multiplying by 100.

[0083] It is desirable that the 50% (D50) integrated value of the volume-based particle size distribution of amorphous carbon be 50 nm or more and 350 nm or less. This 50% (D50) integrated value of the volume-based particle size distribution was measured using a particle size distribution analysis device (device name: BI-DCP Particle Size Analyzer, manufacturer name: Brookhaven Instruments) in accordance with JIS K6217-6.

[0084] The content of amorphous carbon contained in the negative electrode composite material layer (22) is preferably in the range of 25 mass% to 90 mass%, more preferably 30 mass% to 80 mass%, and even more preferably 35 mass% to 75 mass%, when the content of the negative electrode active material (in the case of the first embodiment, the total content of amorphous carbon and alloy-forming elements) is 100 mass%.

[0085] The content of amorphous carbon in the cathode composite material layer (22) can be measured, for example, by heating the cathode composite material layer at a high temperature of about 1000°C under a helium flow mixed with oxygen and quantifying the generated carbon dioxide.

[0086] When the content of the negative electrode active material (in the case of the first embodiment, the total content of amorphous carbon and the first element) is 100 mass%, the alloy forming element is preferably 10 mass% or more and 75 mass% or less, more preferably 20 mass% or more and 70 mass% or less, and still more preferably 25 mass% or more and 65 mass% or less.

[0087] <3. Method for manufacturing a solid secondary battery according to the first embodiment of the present invention>

[0088] Next, a method for manufacturing a solid secondary battery (1) according to the first embodiment of the present invention will be described.

[0089] A solid secondary battery (1) according to the first embodiment of the present invention can be manufactured by, for example, forming a positive electrode layer (10), a negative electrode layer (20), and a solid electrolyte layer (30) by the following method, and then laminating each of the layers.

[0090] (3-1. Bipolar layer manufacturing process)

[0091] First, a slurry (the slurry may be a paste or other slurry) is prepared by adding a positive electrode composite material (positive electrode active material, binder, etc.) constituting the positive electrode composite layer (12) to a non-polar solvent. Then, the obtained slurry is applied onto a positive electrode current collector (11) and dried. Then, the laminate thus obtained is pressed (for example, pressed using hydrostatic pressure) to prepare a positive electrode layer (10). The pressing process may be omitted. The positive electrode layer (10) may be prepared by compressing the positive electrode composite material into a pellet shape or by stretching it into a sheet shape. When the positive electrode layer (10) is prepared in this way, the positive electrode current collector (11) may be a manufactured pellet or a sheet-shaped compressed one.

[0092] (3-2. Cathode layer manufacturing process)

[0093] First, a slurry is prepared by adding a negative electrode composite material (amorphous carbon, first element, etc.) constituting the negative electrode composite material layer (22) to a polar solvent or a non-polar solvent. Then, the slurry is applied onto a negative electrode current collector (21) and dried to form a negative electrode composite material layer (22). At this time, the mass of the negative electrode composite material layer (22) after drying is 1 cm 2 It is preferable to apply the slurry so that the concentration is in the range of 0.3 mg to 2 mg. Then, the negative electrode composite material layer (22) is pressed (for example, pressed using hydrostatic pressure) to manufacture the negative electrode layer (20). The pressing process may be omitted.

[0094] Meanwhile, 1 cm of the negative composite material layer (22) 2 The mass of the cathode can be measured by drilling a hole of a predetermined area through the cathode active material layer on the cathode current collector (21), examining the mass, and subtracting the mass of the cathode current collector (21) from the mass.

[0095] (3-3. Solid electrolyte layer manufacturing process)

[0096] The solid electrolyte layer (30) can be manufactured, for example, using a sulfide-based solid electrolyte.

[0097] First, the starting raw material is processed using a melt quenching method or mechanical milling method.

[0098] For example, in the case of the melt quenching method, starting materials (e.g., Li2S, P2S5, etc.) are mixed in a predetermined amount and made into a pellet shape, reacted at a predetermined reaction temperature in a vacuum, and then quenched to produce a sulfide-based solid electrolyte material. Meanwhile, the reaction temperature of the mixture of Li2S and P2S5 is preferably 400°C to 1000°C, and more preferably 800°C to 900°C. The reaction time is preferably 0.1 hour to 12 hours, and more preferably 1 hour to 12 hours. The quenching temperature of the reactants is usually 10°C or lower, and preferably 0°C or lower. The quenching speed is usually about 1°C / sec to 10,000°C / sec, and preferably about 1°C / sec to 1000°C / sec.

[0099] In the case of the mechanical milling method, starting raw materials (e.g., Li2S, P2S5, etc.) can be stirred and reacted using a ball mill or the like to produce a sulfide-based solid electrolyte material. Meanwhile, the stirring speed and stirring time in the mechanical milling method are not particularly limited, but if the stirring speed is fast, the formation speed of the sulfide-based solid electrolyte material can be accelerated, and if the stirring time is long, the conversion rate of the raw materials into the sulfide-based solid electrolyte material can be increased.

[0100] Thereafter, the mixed raw material obtained by the melting quenching method or mechanical milling method is heat-treated at a predetermined temperature and then pulverized to produce a solid electrolyte in particle form. If the solid electrolyte has a glass transition point, it can be transformed from an amorphous state to a crystalline state through heat treatment.

[0101] Continuing, the solid electrolyte material obtained by the above method can be used to manufacture a solid electrolyte layer (30) using a well-known film forming method such as an aerosol deposition method, a cold spray method, and a sputtering method. Meanwhile, the solid electrolyte layer (30) can be manufactured by pressing solid electrolyte particles. Alternatively, the solid electrolyte layer (30) can be manufactured by mixing a solid electrolyte, a solvent, and a binder, applying and drying the mixture, and then pressing the mixture.

[0102] (3-4. Assembly process of solid secondary batteries)

[0103] A solid secondary battery (1) according to the first embodiment can be manufactured by stacking and pressing the positive electrode layer (10), the negative electrode layer (20), and the solid electrolyte layer (30) so that the solid electrolyte layer (30) is inserted between the positive electrode layer (10) and the negative electrode layer (20) (for example, pressing using hydrostatic pressure).

[0104] <4. Charging method of solid secondary batteries>

[0105] The operation of the solid secondary battery (1) manufactured by the above-described method can be performed while pressure is applied to the solid secondary battery.

[0106] The above 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. The pressure can be applied by a method such as inserting a solid secondary battery (1) into two solid plates such as stainless steel, brass, aluminum, and glass and fastening the two plates with screws.

[0107] In addition, the temperature at which the solid secondary battery (1) according to the first embodiment is operated is not particularly limited, but is preferably 15°C or more and 70°C or less, more preferably 15°C or more and 50°C or less, and it is particularly preferable to operate it at room temperature such as 20°C or more and 30°C or less.

[0108] The solid secondary battery (1) according to the first embodiment can be charged beyond the charging capacity of the negative electrode composite material layer (22). In other words, the negative electrode composite material layer (22) is overcharged. Meanwhile, the charging amount is preferably 2 to 100 times the charging capacity of the negative electrode composite material layer (22), and more preferably 4 to 100 times the charging capacity.

[0109] At the initial stage of charging, lithium is absorbed into the negative electrode composite material layer (22). In other words, the negative electrode active material forms an alloy or compound with the lithium ions that have moved from the positive electrode layer (10). As illustrated in Fig. 2, when the battery is charged beyond the capacity of the negative electrode composite material layer (22), lithium is precipitated between the negative electrode composite material layer (22) and the negative electrode current collector (21), forming a metal layer (23) made of lithium. In this way, a solid-state secondary battery in which lithium is precipitated on the negative electrode during charging to form a metal layer (23) is called a precipitation-type solid-state secondary battery.

[0110] As illustrated in Fig. 3, the metal layer (23) may be formed, for example, within the negative electrode composite material layer (22). In other words, the metal layer (23) may be formed so as to be sandwiched between two separate negative electrode composite material layers (22). The metal layer (23) is mainly composed of lithium (i.e., lithium metal). This phenomenon is due to the inclusion of a specific substance (i.e., an element that forms an alloy or compound with lithium) as the negative electrode active material. When discharging, lithium within the negative electrode composite material layer (22) and the metal layer (23) is ionized and moves toward the positive electrode layer (10). Therefore, the solid secondary battery (1) can use lithium as the negative electrode active material. Furthermore, since the negative electrode composite material layer (22) covers the metal layer (23), it can function as a protective layer for the metal layer (23) and simultaneously suppress the precipitation and growth of dendrites. By this, short circuit and capacity reduction of the solid secondary battery (1) are suppressed, and further, the characteristics of the solid secondary battery (1) can be improved.

[0111] Here, it is preferable that the ratio (i.e., capacity ratio) of the charge capacity of the positive electrode composite material layer (12) and the charge capacity of the negative electrode composite material layer (22) in the aforementioned precipitation-type solid secondary battery satisfies the requirement of the following mathematical expression 1.

[0112] [Mathematical Formula 1]

[0113] 0.01

[0114] a: Charging capacity (mAh) of the positive electrode composite material layer (12)

[0115] b: Charging capacity (mAh) of the negative composite material layer (22)

[0116] When the capacity ratio is 0.01 or more, the thickness of the negative electrode composite material layer (22) can be sufficiently secured, so that the negative electrode composite material layer (22) can easily function as a protective layer for the metal layer, thereby maintaining high characteristics of the solid secondary battery (1). In addition, when the capacity ratio is 0.5 or less, the amount of lithium precipitation from the negative electrode can be sufficiently secured, and the decrease in battery capacity can be suppressed. For the same reason, it is more preferable that the capacity ratio is less than 0.25. In addition, when the capacity ratio is less than 0.25, the output characteristics of the secondary battery can also be further improved.

[0117] ​Here, the charge capacity of the positive electrode composite material layer (12) can be 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 composite material layer (12). When multiple types of positive electrode active materials are used, the value of charge capacity density Х mass for each positive electrode active material is calculated, and the sum of these values ​​becomes the charge capacity of the positive electrode composite material layer (12). The charge capacity of the negative electrode composite material layer (22) is also calculated in the same way. In other words, the charge capacity of the negative electrode composite material layer (22) can be 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 composite material layer (22). When multiple types of negative electrode active materials are used, the value of charge capacity density Х mass for each negative electrode active material is calculated, and the sum of these values ​​becomes the capacity of the negative electrode composite material layer (22). Here, the charge capacity densities of the positive and negative active materials are capacities calculated using an all-solid-state half-cell using lithium metal as opposite poles. In fact, the charge capacities of the positive composite material layer (12) and the negative composite material layer (22) are directly measured by measurements using an all-solid-state half-cell.

[0118] A specific method for directly measuring the charge capacity may be as follows. First, a test cell using the positive electrode composite material layer (12) as the working electrode and Li as the counter electrode is manufactured, and CC-CV charging is performed from the OCV (open circuit voltage) to the upper limit charge voltage, and the charge capacity of the positive electrode composite material layer (12) is measured. The upper limit charge voltage is determined by the standard of JIS C 8712:2015, and can be obtained by applying the provisions of A.3.2.3 (safety requirements when applying a different upper limit charge voltage) of JIS C 8712:2015 to positive electrodes of lithium cobalt acid type and other positive electrodes. A test cell using the negative electrode composite material layer (22) as the working electrode and Li as the counter electrode is manufactured, and CC-CV charging is performed from the OCV (open circuit voltage) to 0.01 V, and the charge capacity of the negative electrode composite material layer (22) is measured.

[0119] A test cell for measuring the charging capacity can be manufactured, for example, by the following method. The positive electrode composite layer (12) or the negative electrode composite layer (22) is made into a disk shape with a diameter of 13 mm. 200 g of a solid electrolyte powder, such as that used in a solid secondary battery (1), is compacted firmly at 40 MPa to make 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. The positive electrode composite layer (12) or the negative electrode composite layer (22) in the shape of a disk is placed on one side of the cylinder, and lithium foil with a diameter of 13 mm and a thickness of 0.03 mm is placed on the opposite side of the cylinder. One stainless steel disk is placed on each side of the cylinder, and the entirety is pressurized at 300 MPa for 1 minute in the axial direction of the cylinder to integrate the contents. The integrated contents are removed from the cylinder and sealed in a case so that a constant pressure of 22 MPa is applied, thereby creating a test cell. The test cell manufactured in the above manner can be charged CC at a current density of, for example, 0.1 mA and then CV charged to 0.02 mA, thereby measuring the charging capacity of the positive electrode composite material layer (12).

[0120] The charge capacity density is calculated by dividing this charge capacity by the mass of each active material. The initial charge capacity of the positive electrode composite material layer (12) and the negative electrode composite material layer (22) may be the initial charge capacity measured during the first cycle of charging. The examples described below use this value.

[0121] <5. Effects of the first embodiment of the present invention>

[0122] According to the first embodiment of the present invention, the FWHM of amorphous carbon contained in the negative electrode composite material layer (22) of the solid secondary battery (1) 002And the oxygen content is within a predetermined range. Accordingly, a precipitation-type solid secondary battery is realized in which lithium is precipitated in layers by overcharging the negative electrode composite material layer (22), and its output characteristics can be significantly improved when charged and discharged under conditions of room temperature and low pressure. In addition, if the BET specific surface area or oil absorption amount of the amorphous carbon is within a predetermined range, the output characteristics of the precipitation-type solid secondary battery can be further improved.

[0123] Meanwhile, according to the first embodiment, since the metal layer (23) of the solid secondary battery (1) is not formed in advance before the first charge, 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.

[0124] <6. Regarding the second embodiment of the present invention>

[0125] <6-1. Configuration of a solid secondary battery according to the second embodiment of the present invention>

[0126] As illustrated in Fig. 4, the configuration of a solid secondary battery (1a) according to a second embodiment will be described. The solid secondary battery (1a) includes a positive electrode layer (10), a negative electrode layer (20), and a solid electrolyte layer (30). The configuration of the positive electrode layer (10) and the solid electrolyte layer (30) is similar to that of the first embodiment described above.

[0127] (Composition of the cathode layer)

[0128] The negative electrode layer (20) includes a negative electrode current collector (21), a negative electrode composite material layer (22), and a metal layer (23). That is, according to the first embodiment described above, a metal layer (23) that did not exist before the first charge is formed between the negative electrode current collector (21) and the negative electrode composite material layer (22) due to overcharging of the negative electrode composite material layer (22). In contrast, according to the second embodiment, as illustrated in FIG. 4, a metal layer (23') is formed in advance between the negative electrode current collector (21) and the negative electrode composite material layer (22) (i.e., before the first charge).

[0129] The composition of the negative electrode current collector (21) and the negative electrode composite material layer (22) is similar to that of the first embodiment described above. The metal layer (23') includes lithium or a lithium alloy. In other words, the metal layer (23') functions as a lithium reservoir. 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 layer (23') may be composed of any one of these alloys or of lithium. Furthermore, the metal layer (23') may be composed of a plurality of types of the above-described alloys. According to the second embodiment, since the metal layer (23') serves as a lithium reservoir, the characteristics of the solid secondary battery (1) can be further improved.

[0130] 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 metal layer (23') may not be able to sufficiently function as a reservoir. 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 rather deteriorate. For this reason, the metal layer (23') may be composed of, for example, a metal foil having the above-mentioned thickness.

[0131] <6-2. Manufacturing method of solid secondary battery according to the second embodiment of the present invention>

[0132] A method for manufacturing a solid secondary battery according to a second embodiment of the present invention will be described. The cathode layer (10) and the solid electrolyte layer (30) are manufactured using the same method as in the first embodiment described above.

[0133] (Cathode layer manufacturing process)

[0134] According to the second embodiment, a negative electrode composite material layer (22) is disposed on a metal layer (23'). The metal layer (23') may be substantially a metal foil. Since it is difficult to form a negative electrode composite material layer (22) on a lithium foil or a lithium alloy foil, the negative electrode layer (20) may be manufactured by the following method.

[0135] First, a negative electrode composite material layer (22) is formed on a base material (e.g., a Ni plate) using the same method as in the first embodiment described above. Specifically, a slurry is prepared by adding the materials constituting the negative electrode composite material layer (22) to a solvent. The slurry is then applied onto the base material and dried. The slurry laminate is then pressurized (e.g., pressurized using hydrostatic pressure) to form the negative electrode composite material layer (22) on the base material. The pressurization process may be omitted.

[0136] Next, a solid electrolyte layer (30) is laminated on the negative electrode composite material layer (22) and pressurized (for example, pressurization using hydrostatic pressure). Then, the base material is removed. Accordingly, a negative electrode composite material layer (22) / solid electrolyte layer (30) laminate is manufactured.

[0137] Next, a metal foil constituting a metal layer (23'), a negative electrode composite material layer (22) / solid electrolyte layer (30) laminate, and a positive electrode layer (10) are sequentially laminated on a negative electrode current collector (21). Then, this is pressurized (for example, pressurized using hydrostatic pressure) to manufacture a solid secondary battery (1a).

[0138] The operation of the solid secondary battery manufactured by the above-described method can be performed while pressure is applied to the solid secondary battery.

[0139] The above pressure may be 0.5 MPa or more and 10 MPa or less. The pressure may be applied by a method such as inserting a solid secondary battery (1) into two solid plates such as stainless steel, brass, aluminum, and glass and fastening the two plates with screws.

[0140] <6-3. Charging method of a solid secondary battery according to the second embodiment of the present invention>

[0141] The charging method of the solid secondary battery (1a) according to the second embodiment of the present invention is the same as the first embodiment described above. In other words, the solid secondary battery (1a) is charged beyond the charging capacity of the negative electrode composite material layer (22). That is, the negative electrode composite material layer (22) is overcharged. At the initial stage of charging, lithium is absorbed into the negative electrode composite material layer (22). When the charging exceeds the capacity of the negative electrode composite material layer (22), lithium is precipitated within the metal layer (23') (or on the metal layer (23')). During discharge, lithium within the negative electrode composite material layer (22) and the metal layer (23') (or on the metal layer (23')) is ionized and moves to the positive electrode layer (10).

[0142] In this way, since lithium is precipitated on the negative electrode layer when charging the solid secondary battery (1a) according to the second embodiment, this solid secondary battery (1a) can also be called a precipitation-type solid secondary battery.

[0143] Meanwhile, as in the first embodiment described above, a metal layer (23) can be additionally formed inside the negative electrode composite material layer (22) by the precipitated lithium.

[0144] <6-4. Effects of the second embodiment of the present invention>

[0145] The solid secondary battery (1a) configured in this manner can have significantly improved output characteristics when charged and discharged under conditions of room temperature and low pressure, as in the first embodiment described above. Furthermore, since the negative electrode composite material 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. Accordingly, short circuits and capacity reduction of the solid secondary battery (1a) are suppressed, and further, the characteristics of the solid secondary battery (1a) are improved.

[0146] <6-5. Third Embodiment of the Present Invention>

[0147] As illustrated in Fig. 5, a thin film (24) may be formed on the surface of the negative electrode current collector (21). The thin film (24) includes an element capable of forming an alloy with lithium. The element may be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, or bismuth. The thin film (24) may be formed of any one of these metals, or may be formed of an alloy thereof. Due to the presence of the thin film (24), the deposition shape of the metal layer (23) becomes flatter (or more uniform), so that the characteristics of the solid secondary battery (1) may be further improved.

[0148] 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 function of the thin film (24) may not be sufficiently exerted. If the thickness of the thin film (24) exceeds 500 nm, the amount of lithium precipitated into the negative electrode may decrease due to lithium absorption by the thin film (24) itself, and thus the characteristics of the solid secondary battery (1) may rather deteriorate. The thin film (24) may be formed on the negative electrode current collector (21) by, for example, vacuum deposition, sputtering, or plating.

[0149] <6-6. Other embodiments of the present invention>

[0150] In the first to third embodiments described above, it has been described that the solid secondary battery is an all-solid-state 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 are also applicable to a solid secondary battery having a solid negative electrode layer and a solid electrolyte layer. For example, they are also applicable to a solid secondary battery in which part or all of the positive electrode layer is not solid, or a solid secondary battery containing an electrolyte in addition to a solid electrolyte.

[0151] While the best embodiments of the present invention have been described in detail with reference to the attached drawings, the present invention is not limited to these embodiments. Those skilled in the art will readily appreciate various modifications and variations within the scope of the technical concepts set forth in the claims, and these will naturally fall within the technical scope of the present invention.

[0152] [Example]

[0153] Hereinafter, the negative electrode composite material according to the present invention, the negative electrode composite material layer formed of the negative electrode composite material, and the solid secondary battery including the negative electrode composite material layer will be described in more detail with examples, but the present invention is not limited to these examples.

[0154] (1. Description of Examples and Comparative Examples)

[0155] <Example 1>

[0156] According to Example 1, amorphous carbon and an alloy-forming element were used as negative active materials, and a negative electrode composite material for a solid secondary battery was manufactured by the following method.

[0157] (1-1. Manufacturing of cathode layer)

[0158] In Example 1, amorphous carbon and an alloy-forming element were used as negative electrode active materials, and a negative electrode layer was manufactured by the following method.

[0159] The alloying element used was silver particles with a particle size of approximately 60 nm (manufactured by DOWA Electronics). The amorphous carbon was amorphous carbon A (oxygen content 0.95 at%, FWHM) which is carbon black and its properties are shown in Table 1. 002 =5.1) was used.

[0160] First, 12 g of amorphous carbon A and 4 g of silver particles were placed in a container, 14 g of NMP solution containing 8 wt% of binder (PVDF) was added, 16 g of zirconia beads (φ2 mm), and a total of 55 g of NMP were added and stirred to prepare a slurry. The slurry was applied using a blade coater on a current collector plated with 1 μm thick Ni on a 10 μm thick Cu foil, dried in the 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 material layer. Meanwhile, the negative electrode composite material layer manufactured in Example 1 had a thickness of 1 cm 2 Although the coating amount is set to 1.0 mg per unit, the coating amount may be in the range of 0.3 mg to 2 mg.

[0161] (1-2. Manufacturing of the anode layer)

[0162] LiNi coated with Li2O-ZrO2 as a cathode active material 0.8 Co 0.15 Al 0.05 Using O2(NCA), the anode layer was manufactured by the following method.

[0163] Argyrodite-type crystal Li6PS5Cl was used as a solid electrolyte. The cathode active material, 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 and stretched into a sheet to produce a cathode composite. Furthermore, the sheet-shaped cathode composite was formed into a square of approximately 2 cm and pressed onto a cathode current collector made of 18 μm aluminum foil to produce a cathode layer.

[0164] (1-3. Manufacturing of solid electrolyte layer)

[0165] An acrylic fiber-based binder was added at a ratio of 2 parts by mass to 100 parts by mass of the above Li6PS5Cl solid electrolyte, and a slurry was prepared by stirring while adding xylene. Using a blade coater, the slurry was applied onto a PET film, dried in the air at 40°C, and then vacuum-dried at 40°C for 12 hours to prepare a solid electrolyte layer.

[0166] (1-4. Manufacturing of all-solid-state secondary batteries)

[0167] An all-solid-state secondary battery was manufactured by sequentially overlapping the positive electrode layer, solid electrolyte layer, and negative electrode layer manufactured by the above method, and sealing them with a laminate film in a vacuum. To prevent the vacuum of the all-solid-state secondary battery from being broken, portions of the positive electrode and negative electrode layers that protrude outside the laminate film serve as terminals of the positive electrode and negative electrode layers.

[0168] The manufacturing process of the all-solid-state secondary battery was completed by hydrostatically treating the all-solid-state secondary battery at 490 MPa for 30 minutes.

[0169] (1-5. Evaluation of all-solid-state secondary batteries)

[0170] Under the following conditions, the charge / discharge characteristics of the all-solid-state secondary battery manufactured in this way were evaluated.

[0171] First, the solid-state secondary battery was sandwiched between two metal plates and screws were tightened to apply an external pressure of 0.3 MPa to the solid-state secondary battery. The solid-state secondary battery was placed in a constant-temperature chamber at 25°C and measured.

[0172] In the first cycle, 0.45 mA / cm until the battery voltage reaches 4.25 V. 2 The battery was charged with a constant current of 0.2 mA and charged with a constant voltage of 4.25 V until the current reached 0.2 mA. After that, the battery was charged with a constant current of 0.5 mA / cm until the battery voltage reached 2.5 V. 2It was discharged with a constant current of 1.48 mA / cm. In the second and third cycles, it was charged under the same conditions as the first cycle, and each cycle was charged with a constant current of 1.48 mA / cm. 2 , 4.5mA / cm 2 The battery was discharged with a constant current until the battery voltage became 2.5 V. As shown in Table 1, the capacity of the third cycle / capacity of the first cycle was 81.0%.

[0173] <Examples 2 to 13, Comparative Examples 1 to 2>

[0174] An all-solid-state secondary battery was manufactured in the same manner as Example 1, except that the amorphous carbon described in Table 1 was used and the ratio of the amorphous carbon and the alloying element was as described in Table 1, and the same evaluation as in Example 1 was performed. The results are shown in Table 1.

[0175] [Table 1]

[0176]

[0177] Meanwhile, in Table 1, amorphous carbons I and K have high lipophilicity, so the oil content cannot be measured based on the measurement principle. However, based on the fact that the oil absorption of amorphous carbon, which is the raw material before oxidation treatment, is about 180, the oil absorption of amorphous carbons I and K may be about 180.

[0178] (2. Consideration)

[0179] Referring to the results of Examples 1 to 13 and Comparative Examples 1 to 2, the FWHM of amorphous carbon used in the negative electrode composite material for an all-solid-state secondary battery 002 When the temperature is 4° to 6° and the oxygen content is 0.5 at% to 10 at% and the total mass of amorphous carbon and alloy-forming elements is 100 mass%, and the content of amorphous carbon is 25 mass% to 90 mass%, the capacity of the third cycle / capacity of the first cycle of the all-solid-state secondary battery can be made a high value that can be endured in practical use even under room temperature and low external pressure conditions.

[0180] Meanwhile, when the all-solid-state secondary batteries of Example 3 and Comparative Example 1 were evaluated at a temperature of 60°C and a pressure of 4 MPa, the capacity of the third cycle / capacity of the first cycle both showed high results of more than 80%.

[0181] Furthermore, referring to Table 1, amorphous carbon with a lower oxygen content tended to have higher battery output under room temperature and low external pressure conditions. Since the upper limit of the oxygen content of carbon black that can be manufactured using current technology is 10, the optimal upper limit in the examples is tentatively set at 10, but this is not limited to this and can have a higher value.

Claims

1. Contains amorphous carbon, an alloy-forming element that forms an alloy with lithium by electrochemical reaction, and a binder, The content of the amorphous carbon is 25 mass% or more and 90 mass% or less, based on 100 mass% of the total mass of the amorphous carbon and the alloy-forming element, Full width at half maximum (FWHM) of the (002) peak of carbon obtained by X-ray diffraction measurement using Cu-Kα line of the above amorphous carbon 002 ) is 4° or more and 6° or less, A precipitation-type solid secondary battery negative electrode composite material, wherein the oxygen content of the amorphous carbon is 0.5 at% or more and 10 at% or less based on 100 at% of the total amorphous carbon.

2. In claim 1, The BET specific surface area calculated by the adsorption isotherm measured by adsorbing nitrogen on the above amorphous carbon is 10 m 2 / g or more 180m 2 / g or less, a cathode composite material for a precipitation-type solid secondary battery.

3. In claim 1, A cathode composite material for a precipitation-type solid secondary battery, wherein the oil absorption amount of the above amorphous carbon is 60 ml / 100 g or more and 400 ml / 100 g or less.

4. In claim 1, A precipitation-type solid secondary battery negative electrode composite material, wherein the 50% (D50) cumulative value of the volume-based particle size distribution of the above amorphous carbon is 50 nm or more and 350 nm or less.

5. In claim 1, A cathode composite material for a precipitation-type solid secondary battery, wherein the alloy-forming element is at least one selected from the group consisting of gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, indium, and zinc.

6. In claim 1, The above amorphous carbon is carbon black, a precipitation-type solid secondary battery negative electrode composite material.

7. A negative electrode current collector, and a negative electrode composite material layer laminated on the negative electrode current collector, A cathode layer for a precipitation-type solid secondary battery, wherein the cathode composite material layer comprises the cathode composite material according to any one of claims 1 to 6.

8. In claim 7, 1 cm of the above negative composite material layer 2 A cathode layer for a precipitation-type solid secondary battery, having a sugar mass of 0.3 mg or more and 2 mg or less.

9. In claim 7, The above negative electrode composite material layer is a negative electrode layer for a precipitation-type solid secondary battery that 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-state secondary battery, wherein the cathode layer is as described in claim 7.

11. In claim 10, The above anode layer comprises a cathode composite material layer, A precipitation-type solid-state secondary battery, wherein the ratio of the initial charge capacity of the positive electrode composite material layer and the initial charge capacity of the negative electrode composite material layer satisfies the following mathematical expression 1: [Mathematical Formula 1] 0.01 <b / a <0.5 a: Initial charge capacity (mAh) of the positive electrode composite layer b: Initial charge capacity (mA) of the negative composite layer.

12. A charging method for a precipitation-type solid-state secondary battery, wherein the precipitation-type solid-state secondary battery described in claim 10 is charged beyond the initial charging capacity of the negative electrode composite material layer.

13. In claim 12, A charging method for a precipitation-type solid-state secondary battery, wherein the charging capacity of the negative electrode composite material layer is at least twice and at most 100 times the initial charging capacity.

14. A method for using a precipitation-type solid-state secondary battery, wherein the precipitation-type solid-state secondary battery described in claim 10 is sandwiched between two plates and charged and discharged while applying pressure.

15. In claim 14, A method of using a precipitation-type solid secondary battery, wherein the above pressure is 0.1 MPa or more and 1 MPa or less.

16. In claim 14, A method of using a precipitation-type solid-state secondary battery, wherein the precipitation-type solid-state secondary battery described in claim 10 is charged and discharged at a temperature of 20°C or higher and 30°C or lower.

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