solid-state batteries

Abstract

A solid-state battery having a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, wherein at least one of the positive electrode layer and the negative electrode layer comprises at least one of a first sulfide solid electrolyte having Li, P, S and carbonate ions, and a second sulfide solid electrolyte having Li, P and S and a composite sulfide solid electrolyte with carbonate.

Description

Technical Field

[0001] This invention relates to solid-state batteries. Background Technology

[0002] Various technologies have been proposed for batteries disclosed in Japanese Patent Application Publication Nos. 2018-080095, 2021-132023, and 2011-165650. Summary of the Invention

[0003] Japanese Patent Application Publication No. 2018-080095 discloses a method for manufacturing a sulfide solid electrolyte. From the viewpoint of temperature characteristics and suppression of thermal chain reactions, there is still room for improvement in batteries using sulfide solid electrolytes.

[0004] The present invention was made in view of the above-mentioned actual situation, and its main objective is to provide a solid-state battery that can improve thermal stability.

[0005] That is, the present invention includes the following embodiments.

[0006] <1>

[0007] A solid-state battery having a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, wherein... At least one of the positive electrode layer and the negative electrode layer comprises at least one of a first sulfide solid electrolyte having Li, P, S and carbonate ions, and a second sulfide solid electrolyte having Li, P and S and a composite sulfide solid electrolyte with carbonate.

[0008] <2>

[0009] According to the solid-state battery of <1>, the negative electrode layer comprises at least one of the first sulfide solid electrolyte and the composite sulfide solid electrolyte.

[0010] <3>

[0011] According to the solid-state battery described in <1> or <2>, the positive electrode layer comprises at least one of the first sulfide solid electrolyte and the composite sulfide solid electrolyte, and an oxide active material.

[0012] <4>

[0013] In any one of <1> to <3>, the solid-state battery comprises at least one of the positive electrode layer and the negative electrode layer containing an active material containing oxygen.

[0014] <5>

[0015] The solid-state battery according to any one of <1> to <4>, wherein... The negative electrode layer comprises at least one of the first sulfide solid electrolyte and the composite sulfide solid electrolyte. The positive electrode layer comprises at least one of the first sulfide solid electrolyte and the composite sulfide solid electrolyte, as well as an oxide active material.

[0016] According to the present invention, it is possible to provide a solid-state battery that can improve thermal stability. Attached Figure Description

[0017] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, in which the same reference numerals denote the same elements.

[0018] Figure 1 This is a cross-sectional schematic diagram illustrating an example of the solid-state battery of the present invention. Detailed Implementation

[0019] The embodiments of the present invention will be described below. Furthermore, matters not specifically mentioned in this specification but necessary for implementing the present invention (e.g., the general structure and manufacturing process of solid-state batteries that do not constitute features of the present invention) can be considered as design considerations for those skilled in the art based on prior art. The present invention can be implemented based on the disclosures in this specification and common technical knowledge in the field.

[0020] In addition, the dimensional relationships (length, width, thickness, etc.) in the attached drawings do not reflect the actual dimensional relationships.

[0021] In this invention, the method for calculating the average particle size is exemplified below. First, for a given particle, the particle size is calculated by considering it as spherical in a transmission electron microscope (TEM) image or scanning electron microscope (SEM) image at an appropriate magnification (e.g., 50,000 to 1,000,000 times). This particle size calculation based on TEM or SEM observations is performed on 2 to 300 particles of the same type, and the average value of these particles is taken as the average particle size.

[0022] In this invention, a solid-state battery is provided, which is a solid-state battery having a positive electrode layer, a solid electrolyte layer and a negative electrode layer, wherein at least one of the above-mentioned positive electrode layer and the above-mentioned negative electrode layer comprises at least one of a first sulfide solid electrolyte having Li element, P element, S element and carbonate ion, and a composite sulfide solid electrolyte having Li element, P element and S element and carbonate.

[0023] According to the present invention, by including a sulfide solid electrolyte or carbonate replaced by carbonate ions in at least one of the positive electrode layer and the negative electrode layer, the ignition temperature shifts to the high-temperature side and the thermal stability is improved.

[0024] According to the present invention, by making at least one of the positive electrode layer and the negative electrode layer containing an active material containing oxygen elements contain a sulfide solid electrolyte or carbonate replaced by carbonate ions, CO2 is generated when abnormally heated, which has a fire extinguishing function and improved thermal stability.

[0025] The solid-state battery of the present invention has a positive electrode layer, a solid electrolyte layer and a negative electrode layer, and may also have a negative electrode containing a negative electrode layer and a positive electrode containing a positive electrode layer.

[0026] In the solid-state battery of the present invention, at least one of the positive electrode layer and the negative electrode layer comprises at least one of a first sulfide solid electrolyte having Li, P, S and carbonate ions, and a second sulfide solid electrolyte having Li, P and S and a composite sulfide solid electrolyte with carbonate. Alternatively, both the positive electrode layer and the negative electrode layer may comprise at least one of the first sulfide solid electrolyte and the composite sulfide solid electrolyte, or both the positive electrode layer and the negative electrode layer may comprise the first sulfide solid electrolyte.

[0027] At least one of the positive and negative electrode layers may contain an active material containing oxygen. If both the positive and negative electrode layers contain active materials containing oxygen, it is permissible as long as the active material in the positive electrode layer and the active material in the negative electrode layer are different types of active materials that generate a potential difference.

[0028] The first sulfide solid electrolyte contains Li, P, S, and carbonate ions. In the first sulfide solid electrolyte, some of the S element can be converted by carbonate ions (CO3-). 2- ) replacement.

[0029] The first sulfide solid electrolyte can be obtained, for example, by synthesizing sulfide glass by amorphizing a raw material composition containing Li2S, Li2CO3, and P2S5 through mechanical grinding, and then heating the sulfide glass at a temperature above the crystallization temperature to produce glass ceramic.

[0030] The ratio of Li2CO3 to the total of Li2S and Li2CO3 can be, for example, more than 5 mol% and less than 70 mol%.

[0031] The composite sulfide solid electrolyte comprises a second sulfide solid electrolyte and a carbonate. The proportion of carbonate in the composite sulfide solid electrolyte is not particularly limited, and can be, for example, 1–70% by mass.

[0032] The second sulfide solid electrolyte contains Li, P, and S elements.

[0033] The first sulfide solid electrolyte and the second sulfide solid electrolyte are collectively referred to as sulfide solid electrolytes.

[0034] Carbonates can be Na2CO3, Li2CO3, K2CO3, NaHCO3, LiHCO3, and KHCO3, etc.

[0035] Sulfide solid electrolytes are electrolytes containing Li, P, and S elements. They may also contain M (where M is at least one of As, Sb, Si, Ge, Sn, B, Al, Ga, and In). Additionally, sulfide solid electrolytes may contain halogen elements such as F, Cl, Br, and I.

[0036] Sulfide solid electrolytes can be glassy (amorphous), glass-ceramic, or crystalline. They can also possess crystalline phases. Examples of such crystalline phases include the Thio-Lisicon type, the sulfide-germanium ore type, and the LGPS type.

[0037] The composition of sulfide solid electrolytes is not particularly limited; examples include xLi₂S·(1-x)P₂S₅ (0.5 ≤ x < 1) and yLiI·zLiBr·(100-yz)(xLi₂S·(1-x)P₂S₅) (0.5 ≤ x < 1, 0 ≤ y ≤ 30, 0 ≤ z ≤ 30). In these compositions, x can satisfy 0.7 ≤ x ≤ 0.8. Other examples of sulfide solid electrolyte compositions include Li 7-x PS 6-x X xX is at least one of F, Cl, Br, and I, and x satisfies 0 ≤ x < 2. Additionally, Li4 is another example of a sulfide solid electrolyte composition. x Me1 x P x S4 (0 < x < 1). Me is at least one of Al, Zn, In, Ge, Si, Sn, Sb, Ga, and Bi. Examples of sulfide solid electrolytes include LiI-LiBr-Li2S-P2S5, LiI-Li2S-P2S5, LiI-Li2S-P2O5, and LiI-Li3PO4-P2S5.

[0038] From the point of view of good operability, sulfide solid electrolytes can be in the form of particles.

[0039] In addition, the average particle size of sulfide solid electrolytes is not particularly limited and can range from 1 nm to 100 μm.

[0040] Figure 1 This is a cross-sectional schematic diagram illustrating an example of the solid-state battery of the present invention.

[0041] like Figure 1 As shown, the solid-state battery 100 of the present invention sequentially comprises a negative electrode layer 10, a solid electrolyte layer 20, and a positive electrode layer 30.

[0042] positive electrode

[0043] The positive electrode has a positive electrode layer and, if necessary, a positive electrode current collector.

[0044] The positive electrode layer is a layer containing at least a positive electrode active material. In addition, the positive electrode layer may, as needed, contain at least one of a first sulfide solid electrolyte and a complex sulfide solid electrolyte, a conductive material, and a binder.

[0045] The positive electrode layer can be disposed on one or both surfaces of the positive electrode current collector. The positive electrode can also form a multilayer structure by forming two or more positive electrode layers on at least one surface of the positive electrode current collector. Furthermore, when forming two or more positive electrode layers, the types of positive electrode active materials contained in each positive electrode layer can be the same or different.

[0046] The positive electrode active material can be an oxygen-containing active material. Examples of oxygen-containing active materials include oxide active materials. Examples of oxide active materials include LiCoO2, LiMnO2, LiNiO2, LiVO2, and LiNi. 1 / 3 Co 1 / 3 Mn 1 / 3O2 and LiNi 0.8 Mn 0.1 Co 0.1 O2 and other layered active substances in rock salt; LiMn2O4, Li4Ti5O 12 and Li(Ni) 0.5 Mn 1.5 Spinel-type active substances such as O4; olivine-type active substances such as LiFePO4, LiMnPO4, LiNiPO4 and LiCoPO4.

[0047] A coating containing a Li-ion-conducting compound can be formed on the surface of the positive electrode active material. This is because it can suppress the reaction between the positive electrode active material and the solid electrolyte (especially a sulfide solid electrolyte). Examples of Li-ion-conducting compounds include B₂O₃, Li₂B₄O₇, LiBPO₄, Li₃PO₄, LiPO₃, and LiNbO₃. The coating thickness is, for example, 1 nm or more and 30 nm or less. The coverage of the positive electrode active material with the Li-ion-conducting compound is, for example, 70% or more, or 90% or more, or even 100%.

[0048] The positive electrode active material is usually in the form of particles. The positive electrode active material can be primary particles or secondary particles formed by the aggregation of primary particles.

[0049] There is no particular limitation on the average particle size of the positive electrode active material. For example, it can be 0.01 μm or more and 50 μm or less, or it can be 0.5 μm or more and 30 μm or less.

[0050] The proportion of positive electrode active material in the positive electrode layer can be, for example, 20% by mass or more, 30% by mass or more, or 40% by mass or more. If the proportion of positive electrode active material is too low, sufficient energy density may not be achieved. On the other hand, the proportion of positive electrode active material in the positive electrode layer can be, for example, 95% by mass or less, 70% by mass or less, or 60% by mass or less. If the proportion of positive electrode active material is too high, the ionic conductivity and electronic conductivity of the positive electrode layer may be relatively reduced.

[0051] The proportion of solid electrolyte in the positive electrode layer can be, for example, 1% or more by mass, 10% or more by mass, or 15% or more by mass. If the proportion of solid electrolyte is too low, the ion conduction pathway in the positive electrode layer may be insufficient. On the other hand, the proportion of solid electrolyte in the positive electrode layer can be, for example, 70% or less by mass, or 50% or less by mass. If the proportion of solid electrolyte is too high, the proportion of positive electrode active material will be relatively reduced, and the energy density may decrease.

[0052] The positive electrode layer can contain conductive materials. By adding conductive materials, the electronic conductivity of the positive electrode layer is improved.

[0053] Examples of conductive materials include carbon-based materials, metal particles, and conductive polymers. Examples of carbon-based materials include particulate materials such as acetylene black (AB) and Ketjen black (KB); and fibrous materials such as vapor-grown carbon fibers (VGCF), carbon nanotubes (CNTs), and carbon nanofibers (CNFs).

[0054] The proportion of conductive material in the positive electrode layer can be, for example, 0.1% by mass or more. If the proportion of conductive material is too low, the electron conduction pathway in the positive electrode layer may be insufficient. On the other hand, the proportion of conductive material in the positive electrode layer can be, for example, 5% by mass or less. If the proportion of conductive material is too high, the proportion of positive electrode active material will be relatively reduced, and the energy density may decrease.

[0055] The positive electrode layer may contain a binder.

[0056] Examples of adhesives include styrene-butadiene rubber (SBR), polyimide (PI), polyacrylic acid (PAA), acrylonitrile-butadiene rubber (NBR), butadiene rubber (BR), polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), styrene-isoprene-styrene block copolymer (SIS), and ethylene-propylene-diene copolymer (EPDM).

[0057] The proportion of binder in the positive electrode layer can be, for example, 0.5% by mass or more. If the proportion of binder is too low, it may not be able to sufficiently reduce the increase in resistance caused by charging and discharging. On the other hand, the proportion of binder in the positive electrode layer can be, for example, 15% by mass or less. If the proportion of binder is too high, the proportion of positive electrode active material will be relatively reduced, and the energy density may decrease.

[0058] The thickness of the positive electrode layer can be, for example, 0.1 μm or more and 1000 μm or less, 1 μm or more and 500 μm or less, or 30 μm or more and 100 μm or less.

[0059] There is no particular limitation on the manufacturing method of the positive electrode layer. For example, the following methods can be used: mixing the positive electrode active material, conductive material, and solvent to obtain a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector; and drying to form the positive electrode layer. Alternatively, the positive electrode layer can be pressed along its thickness direction during the formation process. Examples of pressing processes include rolling and flatbed pressing.

[0060] Examples of solvents include N-methylpyrrolidone (NMP), tetrahydronaphthalene, diisobutyl ketone, butyl butyrate, mesitylene, heptane, dibutyl ether, decane, dodecane, isodecane, and toluene, and may contain two or more of these components.

[0061] Materials used as positive current collectors include, for example, SUS, Cr, Au, Pt, Zn, aluminum, copper, nickel, iron, titanium, and carbon. The thickness of the positive current collector is, for example, 0.1 μm or more and 100 μm or less. The shape of the positive current collector can be foil-like or plate-like. The top view shape of the positive current collector is not particularly limited; for example, circular, elliptical, rectangular, and arbitrary polygonal shapes are possible. The positive current collector can also be composed of a buffer layer, an elastic layer, or a PTC (Positive Temperature Coefficient) thermistor layer disposed on its surface.

[0062] negative electrode

[0063] The negative electrode has a negative electrode layer, and may also have a negative electrode current collector if needed.

[0064] The negative electrode layer is a layer containing at least a negative electrode active material. Additionally, the negative electrode layer may, as needed, contain at least one of a first sulfide solid electrolyte and a complex sulfide solid electrolyte, a conductive material, and a binder. The negative electrode layer may have a larger area than the positive electrode layer.

[0065] The negative electrode active material can be in particle or sheet form. The average particle size of the negative electrode active material can be, for example, 1 μm or more. Alternatively, the average particle size of the negative electrode active material can be, for example, 30 μm or less.

[0066] The negative electrode active material may include at least one selected from the group consisting of carbon-based active materials, Li-based active materials, Si-based active materials, Si-C composite materials, and oxide active materials. The negative electrode active material may be an active material containing oxygen.

[0067] Carbon-based active materials may include at least one selected from the group consisting of graphite, soft carbon, and hard carbon. "Graphite" is a general term for both natural and artificial graphite. Graphite can also be a mixture of natural and artificial graphite.

[0068] Examples of Li-based active materials include Li, Li silicates, and Li alloys.

[0069] Examples of active materials based on Si include Si, SiO, and Si alloys.

[0070] Si-C composite materials refer to composite materials composed of carbon-based active materials (such as graphite) and Si-based active materials (such as Si). For example, Si particles can be dispersed within carbon particles. For example, Si particles can be dispersed within graphite particles. For example, Li silicate particles can be coated with carbon materials (such as amorphous carbon).

[0071] As an oxide active material, substances that are the same as those exemplified in the positive electrode active material can be listed.

[0072] Regarding the solid electrolyte, conductive material, and binder used in the negative electrode layer, the same substances as those described in the positive electrode layer can be listed.

[0073] The proportion of solid electrolyte in the negative electrode layer can be, for example, 1% or more by mass, 15% or more by mass, or 20% or more by mass. On the other hand, the proportion of solid electrolyte in the negative electrode layer can be, for example, 70% or less by mass, or 60% or less by mass.

[0074] The proportion of conductive material in the negative electrode layer can be, for example, more than 0.1% by mass and less than 5% by mass.

[0075] The proportion of binder in the negative electrode layer can be, for example, more than 0.5% by mass and less than 15% by mass.

[0076] The thickness of the negative electrode layer can be, for example, 0.1 μm or more and 1000 μm or less, 1 μm or more and 500 μm or less, or 30 μm or more and 100 μm or less.

[0077] Materials used as negative current collectors include, for example, SUS, aluminum, copper, nickel, iron, titanium, and carbon. Furthermore, the thickness of the negative current collector varies depending on its shape, but can range from, for example, 1 μm to 50 μm. The shape of the negative current collector can be foil-like or plate-like. The top view shape of the negative current collector is not particularly limited; examples include circular, elliptical, rectangular, and arbitrary polygonal shapes. The negative current collector can also be composed of a buffer layer, an elastic layer, or a PTC thermistor layer disposed on its surface.

[0078] solid electrolyte layer

[0079] The solid electrolyte layer is a layer formed between the positive electrode layer and the negative electrode layer, and it contains at least a solid electrolyte.

[0080] The solid electrolyte layer contains at least a solid electrolyte and, if necessary, a binder, etc. The solid electrolyte can be the aforementioned sulfide solid electrolyte.

[0081] Solid electrolytes can be used alone or in combination with two or more. Furthermore, when using two or more solid electrolytes, they can be mixed, or each solid electrolyte layer can be individually layered to form a multilayer structure.

[0082] The proportion of solid electrolyte in the solid electrolyte layer is not particularly limited. For example, it can be 50% or more by mass, or it can be in the range of 60% or more and 100% by mass, or it can be in the range of 70% or more and 100% by mass, or it can be 100% by mass. The solid electrolyte layer may contain less than 1% by mass of electrolyte relative to the total amount of solid electrolyte layer.

[0083] Examples of binders that can be contained in the positive electrode layer include the above-mentioned binders.

[0084] The content of binder in the solid electrolyte layer can be 0% to 10% by mass relative to the total amount of the solid electrolyte layer.

[0085] The thickness of the solid electrolyte layer can be, for example, 0.1 μm or more and 1000 μm or less, or 0.1 μm or more and 500 μm or less.

[0086] The battery of the present invention may further include a constraint clamp that applies constraint pressure to the positive electrode layer, the solid electrolyte layer, and the negative electrode layer along the thickness direction. The constraint pressure may be, for example, 0.1 MPa or more, 1 MPa or more, or 5 MPa or more. On the other hand, the constraint pressure may be, for example, 100 MPa or less, 50 MPa or less, or 20 MPa or less.

[0087] solid-state batteries

[0088] The solid-state battery in this invention can be a semi-solid-state battery or an all-solid-state battery. In this invention, a semi-solid-state battery refers to a battery in which the solid electrolyte layer contains both solid components such as a solid electrolyte and liquid components (e.g., solvents and electrolyte solutions). In this invention, an all-solid-state battery is a battery in which the solid electrolyte layer contains only solid components such as a solid electrolyte. Furthermore, the solid-state battery in this invention can be a primary battery or a secondary battery, especially a secondary battery. This is because it can be repeatedly charged and discharged, making it useful, for example, as a battery for automotive applications.

[0089] Solid-state batteries are not particularly limited in shape; for example, they can be coin-shaped, cylindrical, square, sheet-shaped, button-shaped, flat, or stacked.

[0090] In the case of a battery stack composed of multiple solid-state batteries, the battery stack can be either unipolar or bipolar.

[0091] Applications of solid-state batteries include, for example, powering vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), gasoline vehicles, and diesel vehicles. Specifically, they can be used as power sources for driving hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or battery electric vehicles (BEVs). Furthermore, solid-state batteries can also be used as power sources for mobile bodies other than vehicles (e.g., trains, ships, aircraft) and for electrical products such as information processing devices.

[0092] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any content having a substantially the same structure and achieving the same effect as the technical concept described in the claims of the present invention is included within the technical scope of the present invention.

[0093] Comparative Example 1

[0094] Fabrication of the positive electrode layer

[0095] Based on a weight ratio of positive electrode active material / solid electrolyte / conductive material / binder = 82 / 15 / 2 / 1, butyl butyrate, a 5% wt% butyl butyrate solution of PVDF-based binder, and LiNi as the positive electrode active material with an average particle size of 6 μm were added to a PP container. 1 / 3 Co 1 / 3 Mn 1 / 3 O2, Li2S-P2S5 glass-ceramic as a sulfide solid electrolyte, and VGCF as a conductive material were stirred for 30 seconds using an ultrasonic dispersion device (SMT UH-50).

[0096] Next, the container was shaken for 3 minutes using a shaker (manufactured by Shibata Scientific Co., Ltd., TTM-1), and then stirred for 30 seconds using an ultrasonic dispersion device.

[0097] After oscillating for 3 minutes, the obtained positive electrode slurry is coated onto an Al foil (Showa Denko) using a coater and a scraper method.

[0098] The coated positive electrode slurry is dried on a hot plate at 100°C for 30 minutes. This yields a positive electrode with a positive electrode layer on the positive current collector.

[0099] Fabrication of the negative electrode layer

[0100] By weight ratio, butyl butyrate, a 5% wt% butyl butyrate solution of PVDF binder, VGCF as conductive material, cage-like Si as negative electrode active material, and Li2S-P2S5 glass-ceramic as sulfide solid electrolyte were added to a PP container in the following manner: negative electrode active material / solid electrolyte / conductive material / binder = 52 / 44 / 2.5 / 1.5. The mixture was stirred for 30 seconds using an ultrasonic dispersion device (SMT UH-50).

[0101] Next, the container was shaken for 30 minutes using a shaker (manufactured by Shibata Scientific Co., Ltd., TTM-1). The obtained negative electrode slurry was then coated onto the Ni foil using a coater via a doctor blade method. The coated negative electrode slurry was dried on a hot plate at 100°C for 30 minutes. Thus, a negative electrode with a negative electrode layer on the negative electrode current collector was obtained.

[0102] Fabrication of solid electrolyte layer

[0103] Add heptane, a 5% by weight heptane solution of BR-based binder, and Li2S-P2S5-based glass ceramic as a sulfide solid electrolyte to a PP container, and stir for 30 seconds using an ultrasonic dispersion device (SMT UH-50).

[0104] Next, the container was shaken for 30 minutes using a shaker (Shibata Scientific Co., Ltd., TTM-1). The obtained solid electrolyte slurry was then coated onto an Al foil using a coater via a doctor blade method. The coated solid electrolyte slurry was dried on a hot plate at 100°C for 30 minutes. Thus, a solid electrolyte layer was obtained on the Al foil.

[0105] Battery manufacturing

[0106] The positive electrode layer and the first solid electrolyte layer are stacked in this order. The stack is then placed in a roller press and pressed at a pressing pressure of 100 kN / cm and a pressing temperature of 165°C as the first pressing step to obtain the positive electrode stack.

[0107] The aforementioned negative electrode layer and the Cu foil serving as the negative electrode current collector are stacked in this order. The stack is then placed in a roller press and pressed at a pressing pressure of 60 kN / cm and a pressing temperature of 25°C as the second pressing process, thereby obtaining the negative electrode stack.

[0108] Then, the Al foil, which serves as a release sheet, the intermediate solid electrolyte layer formed on the Al foil, and the aforementioned negative electrode stack having a second solid electrolyte layer, a negative electrode layer, and a Ni foil serving as a negative electrode current collector are stacked in this order.

[0109] The laminate was placed in a planar uniaxial press and pre-pressed for 10 seconds at 100 MPa and 25°C. The Al foil was then peeled off from the intermediate solid electrolyte layer of the laminate to obtain a negative electrode laminate further laminated with an intermediate solid electrolyte layer.

[0110] It should be noted that the negative electrode stack and the positive electrode stack are manufactured with the area of ​​the negative electrode stack being larger than that of the positive electrode stack.

[0111] The above-described positive electrode stack and the negative electrode stack further stacked with an intermediate solid electrolyte layer are stacked in this order. The stack is placed in a planar uniaxial press and pressed for 1 minute at a pressing pressure of 200 MPa and a pressing temperature of 120°C, which is the third pressing process. The resulting stack is then laminated and encapsulated to obtain an all-solid-state battery.

[0112] The weights of each layer in each battery cell are as follows: Positive electrode layer: 15.4 mg, solid electrolyte layer: 3.6 mg, negative electrode layer: 24.1 mg.

[0113] Example 1

[0114] CO3 was used in the fabrication of the aforementioned negative electrode layer. 2- The sulfide solid electrolyte was replaced with a sulfide solid electrolyte, and otherwise an all-solid-state battery (cell) was fabricated using the same method as Comparative Example 1.

[0115] The weights of each layer in each battery cell are as follows: Positive electrode layer: 15.5 mg, solid electrolyte layer: 3.6 mg, negative electrode layer: 24.1 mg.

[0116] For each battery cell fabricated in Example 1 and Comparative Example 1, a constraint fixture was used to constrain the cells under a specified constraint pressure, and constant current-constant voltage (CCCV) charging was performed at 1 / 10C until 4.55V was reached.

[0117] Fire test

[0118] The laminates were taken from each battery cell of Example 1 and Comparative Example 1 after charging and used as samples.

[0119] In dry air with a dew point of -30°C, the laminate was placed on a hot plate at 325°C with the positive electrode face as the lower surface for a heating test.

[0120] The temperature of the lower surface of the laminate was measured, and if ignition occurred, the ignition temperature was taken as the ignition temperature. The results are shown in Table 1.

[0121] (Table 1)

[0122] As shown in Table 1, the ignition temperature of the laminate heated on a hot plate at 325°C was 238°C in Comparative Example 1 and above 281°C in Example 1. Furthermore, it can be seen that no ignition occurred in Example 1, reaching a maximum temperature of 281°C or higher. It is evident that CO3 is used at least in the negative electrode layer. 2- When the sulfide solid electrolyte is replaced, the ignition temperature increases, and the thermal stability of the battery cell improves. It is speculated that CO3 is used in the positive electrode layer. 2- Replacing the sulfide solid electrolyte can also achieve the same effect as when used in the negative electrode layer.

[0123] Comparative Example 2

[0124] Fabrication of positive electrode composite materials

[0125] LiNi with an average particle size of 6 μm was used as the positive electrode active material. 1 / 3 Co 1 / 3 Mn 1 / 3 A positive electrode composite material was prepared using O2, Li2S-P2S5-based glass ceramic as a sulfide solid electrolyte, and VGCF as a conductive material. 800 mg of positive electrode active material, 200 mg of solid electrolyte, and 20 mg of VGCF were weighed and mixed in a mortar to obtain the positive electrode composite material.

[0126] Fabrication of negative electrode composite materials

[0127] A negative electrode composite material was prepared using Si as the negative electrode active material, Li2S-P2S5-based glass ceramic as the sulfide solid electrolyte, and VGCF as the conductive material. The negative electrode composite material was prepared by mixing 450 mg of the negative electrode active material, 450 mg of the solid electrolyte, and 10 mg of VGCF in a mortar.

[0128] Fabrication of pressed battery cells

[0129] 70 mg of Li2S-P2S5-based glass ceramic as a solid electrolyte was added into an alumina cylinder with a diameter of 11.28 mm, and pressed with 1 ton of material to form a solid electrolyte layer.

[0130] Next, 25 mg of positive electrode composite material is added to one side of the solid electrolyte layer and pressed with 1 ton to produce a positive electrode laminate. Then, 8.35 mg of negative electrode composite material is added to the other side and pressed with 6 tons to produce a negative electrode laminate. The laminated battery cell (battery unit) is fabricated using the above method.

[0131] The fabricated battery cells are constrained under specified pressure and charged at 1 / 10C with constant current and constant voltage until 4.55V is reached. Then, they are discharged at 1 / 10C with constant current and constant voltage until 4.35V is reached.

[0132] After charging and discharging, the battery cells are disassembled and the positive electrode laminate and negative electrode laminate are recycled.

[0133] Example 2

[0134] In the fabrication of the aforementioned positive electrode composite material, CO3 is used. 2- In the fabrication of the aforementioned negative electrode composite material, CO3 is used to replace the sulfide solid electrolyte. 2- The sulfide solid electrolyte was replaced with a sulfide solid electrolyte. Otherwise, the pressed battery cell was made by the same method as in Comparative Example 2. After charging and discharging, the battery cell was disassembled and the positive electrode laminate and negative electrode laminate were recovered.

[0135] TPD-MS analysis

[0136] Device: Shimadzu GC / MS QP2010 plus (10)

[0137] Heating conditions: Temperature rise from room temperature to 500℃ (heating rate 10℃ / minute)

[0138] Atmosphere: He gas flow (50 mL / min)

[0139] Under the above conditions, TPD-MS analysis was performed on the recovered positive and negative electrode laminates to evaluate CO2 production. The results are shown in Table 2.

[0140] (Table 2)

[0141] As shown in Table 2, in an oxygen-rich environment where oxygen-containing active materials are used as the positive electrode active material and oxygen is released from the positive electrode active material, the results of Example 2 show that if CO3 is included in the positive electrode layer... 2- Replacing the sulfide solid electrolyte will produce CO2, which has a fire extinguishing effect.

[0142] On the other hand, it can be seen that when using oxygen-free Si as the negative electrode active material in the negative electrode layer, even if the negative electrode layer contains CO3... 2- Replacing sulfide solid electrolytes, since there is no oxygen release, will not produce CO2 and will not perform fire extinguishing functions. It is speculated that if an oxygen-containing active material is used as the negative electrode active material and CO3 is included in the negative electrode layer... 2- Replacing the sulfide solid electrolyte will produce CO2, which has a fire-extinguishing effect, just as when it is contained in the positive electrode layer.

[0143] Based on the results of Example 1 in Table 1 and Example 2 in Table 2, it can be seen that by using CO3 in the negative electrode layer... 2-Replacing the sulfide solid electrolyte increases the ignition temperature of the battery cell and improves its thermal stability.

Claims

1. A solid-state battery, comprising a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, wherein, At least one of the positive electrode layer and the negative electrode layer comprises at least one of a first sulfide solid electrolyte having Li, P, S and carbonate ions, and a second sulfide solid electrolyte having Li, P and S and a composite sulfide solid electrolyte with carbonate.

2. The solid-state battery according to claim 1, wherein, The negative electrode layer comprises at least one of the first sulfide solid electrolyte and the composite sulfide solid electrolyte.

3. The solid-state battery according to claim 1, wherein, The positive electrode layer comprises at least one of the first sulfide solid electrolyte and the composite sulfide solid electrolyte, as well as an oxide active material.

4. The solid-state battery according to claim 1, wherein, At least one of the positive electrode layer and the negative electrode layer contains an active material containing oxygen.

5. The solid-state battery according to claim 1, wherein, The negative electrode layer comprises at least one of the first sulfide solid electrolyte and the composite sulfide solid electrolyte. The positive electrode layer comprises at least one of the first sulfide solid electrolyte and the composite sulfide solid electrolyte, as well as an oxide active material.

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