Solid-state battery and manufacturing method for the same

Abstract

To provide a solid-state battery capable of suppressing resistance increase.SOLUTION: The solid-state battery includes, in this order, a positive electrode active material layer 110, a solid electrolyte layer 120, and a negative electrode active material layer 130. The positive electrode active material layer 110, the solid electrolyte layer 120, and the negative electrode active material layer 130 contain moisture. (i) The moisture content of the positive electrode active material layer 110 is from 100 to 350 ppm, the moisture content of the solid electrolyte layer 120 is from 500 to 1400 ppm, and the moisture content of the negative electrode active material layer 130 is from 400 to 1200 ppm. (ii) And / or, the hydroxyl group standard value of the positive electrode active material layer 110 is from 0.63 to 0.71, the hydroxyl group standard value of the solid electrolyte layer 120 is from 0.61 to 0.85, and the hydroxyl group standard value of the negative electrode active material layer 130 is from 0.66 to 2.85.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a solid-state battery and a method for manufacturing the same.

Background Art

[0002] A solid-state battery is a secondary battery containing a solid electrolyte as an electrolyte, and has attracted attention because it has higher safety compared to a liquid-based battery using an electrolytic solution as an electrolyte. The output of a solid-state battery is smaller than that of a liquid-based battery, and various developments have been made for its improvement. The following electrochemical elements containing a solid electrolyte are known.

[0003] Patent Document 1 discloses an electrochemical element including a laminate having a positive electrode, a negative electrode, and a solid electrolyte sandwiched between the positive electrode and the negative electrode, the laminate containing moisture, and the amount of moisture contained in the laminate being 0.001% by mass or more and less than 0.3% by mass with respect to the laminate. According to the electrochemical element of Patent Document 1, it is said that the operation can be maintained when a high voltage is applied.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] For example, as in Patent Document 1, it is known to improve the performance of a solid-state battery by uniformly adsorbing a predetermined amount of moisture to an electrode laminate including a solid electrolyte. However, it is not well known about appropriately adsorbing appropriate moisture to the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer, rather than the entire electrode laminate, and about a solid-state battery using them and its performance.

[0006] Therefore, an object of the present disclosure is to provide a solid-state battery capable of suppressing an increase in resistance.

Means for Solving the Problems

[0007] The present disclosure achieves the above object by the following means.

[0008] 〈Aspect 1〉 A solid battery having a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in this order, wherein the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer contain moisture, (i) the moisture content of the positive electrode active material layer is 100 to 350 ppm, the moisture content of the solid electrolyte layer is 500 to 1400 ppm, and the moisture content of the negative electrode active material layer is 400 to 1200 ppm, and / or (ii) the hydroxyl group standard value of the positive electrode active material layer is 0.63 to 0.71, the hydroxyl group standard value of the solid electrolyte layer is 0.61 to 0.85, and the hydroxyl group standard value of the negative electrode active material layer is 0.66 to 2.85. Solid battery. 〈Aspect 2〉 The solid battery according to Aspect 1, wherein the solid electrolyte layer contains a sulfide solid electrolyte. 〈Aspect 3〉 Part of the moisture contained in the positive electrode active material layer is physically adsorbed water physically adsorbed on the positive electrode active material layer, and the moisture content of the physically adsorbed water is 0.50 to 0.90 with respect to the moisture content of the positive electrode active material layer. The solid battery according to Aspect 1 or 2. 〈Aspect 4〉 A method for manufacturing a solid battery according to any one of Aspects 1 to 3, including the following steps: Adsorbing moisture on the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer in an environment with a dew point of 0°C or lower, and Stacking the moisture-adsorbed positive electrode active material layer, the moisture-adsorbed solid electrolyte layer, and the moisture-adsorbed negative electrode active material layer in this order to obtain a solid battery.

Advantages of the Invention

[0009] According to the solid-state battery of the present disclosure, an increase in resistance can be suppressed.

Brief Description of the Drawings

[0010]

Figure 1

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present disclosure will be described in detail. Note that the present disclosure is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present disclosure. Also, in the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[0012] Regarding the present disclosure, "composite material" means a composition that can form a positive electrode active material layer or the like as it is or by further containing other components. Also, regarding the present disclosure, "composite material slurry" means a slurry that contains a dispersion medium in addition to the "composite material" and can form a positive electrode active material layer or the like by coating and drying it.

[0013] Regarding the present disclosure, "solid-state battery" means a battery that uses at least a solid electrolyte as an electrolyte. Therefore, the solid-state battery of the present disclosure may use a combination of a solid electrolyte and a liquid electrolyte as the electrolyte. Also, the solid-state battery of the present disclosure may be an all-solid-state battery, that is, a battery that uses only a solid electrolyte as the electrolyte.

[0014] 《Solid-State Battery》 The solid-state battery of the present disclosure has a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in this order, the above positive electrode active material layer, the above solid electrolyte layer, and the above negative electrode active material layer contain moisture, (i) the moisture content of the above positive electrode active material layer is 100 to 350 ppm, the moisture content of the above solid electrolyte layer is 500 to 1400 ppm, and the moisture content of the above negative electrode active material layer is 400 to 1200 ppm, and / or (ii) The hydroxyl group standard value of the above positive electrode active material layer is 0.63 to 0.71, the hydroxyl group standard value of the above solid electrolyte layer is 0.61 to 0.85, and the hydroxyl group standard value of the above negative electrode active material layer is 0.66 to 2.85.

[0015] According to the solid battery of the present disclosure, an increase in resistance can be suppressed.

[0016] Although not limited to theory, a predetermined amount of moisture adsorbed in the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer penetrates to the interface between the positive electrode active material layer and the solid electrolyte layer, and a reaction layer having an appropriate thickness is formed at this interface. It is presumed that the oxidative decomposition of the solid electrolyte during charging is suppressed by this reaction layer, thereby suppressing an increase in resistance.

[0017] FIG. 1 is a schematic diagram showing one aspect of the solid battery of the present disclosure, but is not limited to this case.

[0018] The solid battery 100 has a positive electrode active material layer 110, a solid electrolyte layer 120, and a negative electrode active material layer 130 in this order, and a predetermined amount of moisture is contained in the positive electrode active material layer 110, the solid electrolyte layer 120, and the negative electrode active material layer 130. An increase in the resistance of the solid battery can be suppressed by a predetermined amount of moisture contained in the positive electrode active material layer 110, the solid electrolyte layer 120, and the negative electrode active material layer.

[0019] <Configuration of Solid Battery> The solid battery of the present disclosure has a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in this order. The solid battery of the present disclosure may optionally have a positive electrode current collector layer and a negative electrode current collector layer, and may have a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer in this order.

[0020] <Positive Electrode Current Collector Layer> The material used for the positive electrode current collector layer is not particularly limited, but those commonly used as the positive electrode current collector of a solid battery can be appropriately adopted. Examples of the material used for the positive electrode current collector layer include, but are not limited to, Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, stainless steel, etc. Also, the positive electrode current collector layer may have some coating layer on its surface for the purpose of adjusting resistance or the like. Further, the positive electrode current collector layer may be a metal foil or a substrate with the above-mentioned metal electroplated or vapor-deposited thereon.

[0021] The shape of the positive electrode current collector layer is not particularly limited, and examples thereof include a foil shape, a plate shape, or a mesh shape. Among these, a foil shape is preferred.

[0022] The thickness of the positive electrode current collector layer is not particularly limited, and it may be 0.1 μm or more, or 1 μm or more, and may also be 1 mm or less, or 100 μm or less.

[0023] 〈Positive Electrode Active Material Layer〉 The positive electrode active material layer contains at least a positive electrode active material and moisture, and may further optionally contain a solid electrolyte, a conductive assistant, a binder, etc. The positive electrode active material layer may also contain various other additives. The content of each of the positive electrode active material, solid electrolyte, conductive assistant, binder, etc. in the positive electrode active material layer may be appropriately determined according to the intended battery performance. For example, taking the whole of the positive electrode active material layer (the whole solid content) as 100% by mass, the content of the positive electrode active material may be 40% by mass or more, 50% by mass or more, 60% by mass or more, and may also be less than 100% by mass, or 90% by mass or less.

[0024] (Water Content of Positive Electrode Active Material Layer) In the solid-state battery of the present disclosure, the moisture content of the positive electrode active material layer is 100 to 350 ppm. From the perspective of forming the reaction layer, the moisture content of the positive electrode active material layer may be 100 ppm or more, 150 ppm or more, 200 ppm or more, or 250 ppm or more, and from the perspective of suppressing hydrolysis of the solid electrolyte, it may be 350 ppm or less, 340 ppm or less, or 330 ppm or less. The moisture content of the positive electrode active material layer can be measured using a Karl Fischer apparatus (Karl Fischer apparatus CA-310 and moisture vaporization apparatus VA-300 manufactured by Nitto Seiko). Specifically, the positive electrode active material layer is heated to 200 °C with the moisture vaporization apparatus VA-300, and the moisture generated by the heating is measured by the Karl Fischer apparatus CA-310, and the moisture content can be determined.

[0025] (Hydroxyl group standard value of the positive electrode active material layer) In the solid-state battery of the present disclosure, the hydroxyl group standard value of the positive electrode active material layer is 0.63 to 0.71. From the perspective of forming the reaction layer, the hydroxyl group standard value of the positive electrode active material layer may be 0.63 or more, 0.64 or more, 0.65 or more, 0.66 or more, 0.67 or more, or 0.68 or more, and from the perspective of suppressing hydrolysis of the solid electrolyte, it may be 0.71 or less, 0.70 or less, or 0.69 or less. The hydroxyl group standard value of the positive electrode active material layer is determined by Fourier transform infrared spectroscopy (FT-IR) by measuring the absorbance at 3300 cm ―1 of the positive electrode active material layer and the absorbance at 1180 cm ―1 and calculating the ratio of the absorbance at 3300 cm -1 to the absorbance at 1180 cm -1 as the hydroxyl group standard value of the positive electrode active material layer.

[0026] (Moisture content of physically adsorbed water with respect to the moisture content contained in the positive electrode active material layer) Part of the moisture contained in the positive electrode active material layer may be physically adsorbed water that is physically adsorbed to the positive electrode active material layer, although it is not particularly limited. The amount of physically adsorbed water is not particularly limited, but may be 0.50 to 0.90 with respect to the amount of moisture contained in the positive electrode active material layer. The amount of physically adsorbed water with respect to the amount of moisture contained in the positive electrode active material layer may be 0.50 or more, 0.55 or more, 0.60 or more, 0.65 or more, or 0.70 or more, and may be 0.90 or less, 0.85 or less, 0.80 or less, or 0.75 or less. The amount of physically adsorbed water with respect to the amount of moisture contained in the positive electrode active material layer can be determined from the generation rate curve of water (m / z = 18) measured under the conditions of a measurement temperature of 30 to 500 °C and a heating rate of 10 °C / min by thermogravimetric analysis-mass spectrometry (TPD-MS). Specifically, as the amount of physically adsorbed water, the amount of water generated when the temperature is raised to 100 °C is calculated from the peak area at the measurement temperature of 30 to 100 °C of the water generation rate curve, and then, as the amount of moisture contained in the positive electrode active material layer, the amount of water generated when the temperature is raised to 120 °C is calculated from the peak area at the measurement temperature of 30 to 120 °C of the water generation rate curve. And from the respectively calculated amounts of moisture, the amount of physically adsorbed water with respect to the amount of moisture contained in the positive electrode active material layer can be calculated and determined.

[0027] (Positive electrode active material) The material of the positive electrode active material is not particularly limited as long as it can occlude and release lithium ions. Examples of the positive electrode active material include lithium cobaltate (LiCoO2), lithium nickelate (LiNiO2), lithium manganate (LiMn2O4), lithium nickel cobalt manganate (NCM: LiCO 1 / 3 Ni 1 / 3 Mn 1 / 3 O2), lithium nickel cobalt aluminum oxide (LiNi 0.8 (CoAl) 0.2 O2), Li 1+x Mn 2-x-y M y O4 (M is one or more metal elements selected from Al, Mg, Co, Fe, Ni, and Zn), such as a hetero-element substituted Li-Mn spinel having a composition represented by the formula, but is not limited thereto.

[0028] The positive electrode active material is not particularly limited, but may have a coating layer. The coating layer is a layer containing a material that has lithium ion conduction performance, low reactivity with the positive electrode active material and the solid electrolyte, and can maintain the form of a coating layer that does not flow even when in contact with the active material and the solid electrolyte. Specific examples of the material constituting the coating layer include, in addition to LiNbO3, Li4Ti5O 12 , Li3PO4, Li-Ti-Al-F-based materials, etc., but are not limited thereto.

[0029] The shape of the positive electrode active material is not particularly limited as long as it is a general shape as the positive electrode active material of a solid battery. The positive electrode active material may be, for example, particulate. The positive electrode active material may be primary particles or secondary particles in which a plurality of primary particles are aggregated. The average particle diameter D 50 of the positive electrode active material may be, for example, 1 nm or more, 5 nm or more, or 10 nm or more, and may also be 500 μm or less, 100 μm or less, 50 μm or less, or 30 μm or less. The average particle diameter D 50 is the particle diameter (median diameter) at the integrated value of 50% in the volume-based particle size distribution determined by the laser diffraction / scattering method.

[0030] (Solid electrolyte) The material of the solid electrolyte is not particularly limited and may be, for example, a sulfide solid electrolyte, an oxide solid electrolyte, or a polymer electrolyte.

[0031] Examples of the sulfide solid electrolyte include, but are not limited to, sulfide-based amorphous solid electrolytes, sulfide-based crystalline solid electrolytes, or argyrodite-type solid electrolytes. Specific examples of the sulfide solid electrolyte include Li2S-P2S5-based (Li7P3S 11 , Li3PS4, Li8P2S9, etc.), Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-LiBr-Li2S-P2S5, Li2S-P2S5-GeS2 (Li 13 GeP3S 16 , Li 10 GeP2S 12etc.), LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li 7-x PS 6-x Cl x etc.; or combinations thereof can be mentioned, but are not limited thereto.

[0032] Examples of oxide solid electrolytes include Li7La3Zr2O 12 、Li 7-x La3Zr 1-x Nb x O 12 、Li 7-3x La3Zr2Al x O 12 、Li 3x La 2 / 3-x TiO3、Li 1+x Al x Ti 2-x (PO4)3、Li 1+x Al x Ge 2-x (PO4)3、Li3PO4, or Li 3+x PO 4-x N x (LiPON), etc., but are not limited thereto.

[0033] Sulfide solid electrolytes and oxide solid electrolytes may be glass or crystallized glass (glass ceramics).

[0034] Examples of polymer electrolytes include polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof, etc., but are not limited thereto.

[0035] (Conductive aid) The conductive aid is not particularly limited. The conductive aid may be, for example, vapor-grown carbon fiber (VGCF), acetylene black (AB), ketjen black (KB), carbon nanotube (CNT), carbon nanofiber (CNF), conductive carbon, etc., but is not limited thereto. The conductive aid may be, for example, particulate or fibrous, and its size is not particularly limited. The conductive aid is not particularly limited, but only one kind may be used alone, or two or more kinds may be used in combination.

[0036] (Binder) The binder is not particularly limited. The binder may be, for example, a material such as polyvinylidene fluoride (PVdF), butadiene rubber (BR), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), etc., but is not limited thereto. The binder is not particularly limited, but only one kind may be used alone, or two or more kinds may be used in combination.

[0037] The shape of the positive electrode active material layer is not particularly limited, but may be, for example, a sheet-like positive electrode active material layer having a substantially flat surface. The thickness of the positive electrode active material layer is not particularly limited, but may be, for example, 0.1 μm or more, 1 μm or more, or 10 μm or more, and may also be 2 mm or less, 1 mm or less, or 500 μm or less.

[0038] The positive electrode active material layer can be manufactured by applying a known method. For example, the positive electrode active material layer can be easily formed by molding a positive electrode composite material containing the above various components in a dry or wet manner. The positive electrode active material layer may be formed together with the positive electrode current collector layer, or may be formed separately from the positive electrode current collector layer.

[0039] 〈Solid electrolyte layer〉 The solid electrolyte layer contains at least a solid electrolyte and moisture, and may contain a conductive aid, a binder, etc. as required. The solid electrolyte layer is not particularly limited, but preferably contains a sulfide solid electrolyte.

[0040] (Moisture content of the solid electrolyte layer) In the solid-state battery of the present disclosure, the moisture content of the solid electrolyte layer is 500 to 1400 ppm. From the perspective of forming the reaction layer, the moisture content of the solid electrolyte layer may be 500 ppm or more, 700 ppm or more, 900 ppm or more, 1100 ppm or more, or 1300 ppm or more, and from the perspective of suppressing hydrolysis of the solid electrolyte, it may be 1400 ppm or less, or 1350 ppm or less. For the measurement of the moisture content of the solid electrolyte layer, reference can be made to the description of "(Moisture content of the positive electrode active material layer)" above.

[0041] (Hydroxyl group standard value of the solid electrolyte layer) In the solid-state battery of the present disclosure, the hydroxyl group standard value of the solid electrolyte layer is 0.61 to 0.85. From the perspective of forming the reaction layer, the hydroxyl group standard value of the solid electrolyte layer may be 0.61 or more, 0.63 or more, 0.65 or more, or 0.70 or more, and from the perspective of suppressing hydrolysis of the solid electrolyte, it may be 0.85 or less, 0.84 or less, or 0.83 or less. For the measurement of the hydroxyl group standard value of the solid electrolyte layer, reference can be made to the description of "(Hydroxyl group standard value of the positive electrode active material layer)" above.

[0042] For the solid electrolyte, conductive assistant, and binder, reference can be made to the description of "<Positive electrode active material layer>" above.

[0043] The thickness of the solid electrolyte layer is not particularly limited. For example, it may be 0.1 μm or more, 1 μm or more, or 10 μm or more, and may also be 2 mm or less, 1 mm or less, or 500 μm or less.

[0044] The solid electrolyte layer can be easily formed, for example, by molding a solid electrolyte composite material containing the above-mentioned solid electrolyte and binder, etc. in a dry or wet manner.

[0045] 〈Negative electrode active material layer〉 The negative electrode active material layer contains at least a negative electrode active material and moisture, and may further optionally contain a conductive assistant, a binder, a solid electrolyte, etc. The negative electrode active material layer may also contain various other additives. The content of each of the negative electrode active material, solid electrolyte, conductive assistant, binder, etc. in the negative electrode active material layer may be appropriately determined according to the intended battery performance. For example, assuming the total of the negative electrode active material layer (total solid content) is 100% by mass, the content of the negative electrode active material may be 40% by mass or more, 50% by mass or more, or 60% by mass or more, and may also be less than 100% by mass, or 90% by mass or less.

[0046] (Water content of the negative electrode active material layer) In the solid battery of the present disclosure, the water content of the negative electrode active material layer is 400 to 1200 ppm. From the perspective of forming the reaction layer, the water content of the negative electrode active material layer may be 400 ppm or more, 600 ppm or more, 800 ppm or more, or 1000 ppm or more, and from the perspective of suppressing the hydrolysis of the solid electrolyte, it may be 1200 ppm or less, or 1180 ppm or less. For the measurement of the water content of the negative electrode active material layer, reference can be made to the description of "(Water content of the positive electrode active material layer)" above.

[0047] (Hydroxyl group standard value of the solid electrolyte layer) In the solid battery of the present disclosure, the hydroxyl group standard value of the negative electrode active material layer is 0.66 to 2.85. From the perspective of forming the reaction layer, the hydroxyl group standard value of the negative electrode active material layer may be 0.66 or more, 1.00 or more, 1.50 or more, 2.00 or more, or 2.50 or more, and from the perspective of suppressing the hydrolysis of the solid electrolyte, it may be 2.85 or less, 2.84 or less, or 2.83 or less. For the measurement of the hydroxyl group standard value of the negative electrode active material layer, reference can be made to the description of "(Hydroxyl group standard value of the positive electrode active material layer)" above.

[0048] (Negative electrode active material) As the negative electrode active material, various materials having a potential (charge-discharge potential) for occluding and releasing lithium ions that is lower than that of the positive electrode active material of the present disclosure can be adopted. The material of the negative electrode active material is not particularly limited, and may be metallic lithium, or may be a material capable of occluding and releasing metal ions such as lithium ions. Examples of materials capable of occluding and releasing metal ions such as lithium ions include, but are not limited to, alloy-based negative electrode active materials, carbon materials, or lithium titanate (Li4Ti5O 12 ), etc.

[0049] The alloy-based negative electrode active material is not particularly limited, and examples thereof include Si alloy-based negative electrode active materials or Sn alloy-based negative electrode active materials. The Si alloy-based negative electrode active material includes silicon, silicon oxide, silicon carbide, silicon nitride, or a solid solution thereof. Further, the Si alloy-based negative electrode active material can contain metal elements other than silicon, such as Fe, Co, Sb, Bi, Pb, Ni, Cu, Zn, Ge, In, Sn, Ti, etc. The Sn alloy-based negative electrode active material includes tin, tin oxide, tin nitride, or a solid solution thereof. Further, the Sn alloy-based negative electrode active material can contain metal elements other than tin, such as Fe, Co, Sb, Bi, Pb, Ni, Cu, Zn, Ge, In, Ti, Si, etc.

[0050] The carbon material is not particularly limited, and examples thereof include hard carbon, soft carbon, graphite, etc.

[0051] The shape of the negative electrode active material is not particularly limited, but may be a general shape as the negative electrode active material of a solid battery. The negative electrode active material may be, for example, particulate or sheet-like.

[0052] The solid electrolyte, conductive auxiliary agent, and binder that can be included in the negative electrode active material layer can refer to the description of the above "〈Positive Electrode Active Material Layer〉".

[0053] The shape of the negative electrode active material layer is not particularly limited, and for example, it may be a sheet-shaped negative electrode active material layer having a substantially flat surface. The thickness of the negative electrode active material layer is not particularly limited, and for example, it may be 0.1 μm or more, 1 μm or more, or 10 μm or more, and may also be 2 mm or less, 1 mm or less, or 500 μm or less.

[0054] The negative electrode active material layer can be manufactured by applying a known method. For example, the negative electrode active material layer can be easily formed by molding a negative electrode composite material containing the above various components in a dry or wet manner. The negative electrode active material layer may be formed together with the negative electrode current collector layer, or may be formed separately from the negative electrode current collector layer.

[0055] 〈Negative electrode current collector layer〉 The material used for the negative electrode current collector layer is not particularly limited, and generally used materials for the negative electrode current collector of a solid battery can be appropriately adopted. Examples of the material used for the negative electrode current collector layer include Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, stainless steel, or a carbon sheet, etc., but are not limited to these cases. The negative electrode current collector layer may have some coating layer on its surface for the purpose of adjusting resistance or the like.

[0056] The shape of the negative electrode current collector layer is not particularly limited, and examples thereof include a foil shape, a plate shape, or a mesh shape, etc. Among these, a foil shape is preferred.

[0057] The thickness of the negative electrode current collector layer is not particularly limited, and it may be 0.1 μm or more, or 1 μm or more, and may also be 1 mm or less, or 100 μm or less.

[0058] 〈Shape of solid battery, etc.〉 Examples of the shape of the solid battery include a coin type, a laminate type, a cylindrical type, and a square type, but are not limited to these cases.

[0059] 《Manufacturing method of solid battery》 The solid battery of the present disclosure can be manufactured by a manufacturing method including the following steps. In an environment with a dew point below 0°C, adsorbing moisture onto the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer, and obtaining a solid-state battery by laminating the positive electrode active material layer with adsorbed moisture, the solid electrolyte layer with adsorbed moisture, and the negative electrode active material layer with adsorbed moisture in this order.

[0060] According to the method for manufacturing a solid-state battery of the present disclosure, a solid-state battery capable of suppressing an increase in resistance can be manufactured.

[0061] (Method for Adsorbing Moisture) As a method for adsorbing moisture onto the positive electrode active material layer, for example, the positive electrode active material layer can be left standing in a glove box or the like whose humidity has been adjusted to a dew point of -60°C for a predetermined time to adsorb moisture, but it is not limited to this case. The method for adsorbing moisture onto the solid electrolyte layer and the negative electrode active material layer is the same as that of the positive electrode active material layer.

[0062] The dew point of the environment in which moisture is attached to the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer may be 0°C or lower, -10°C or lower, -30°C or lower, or -50°C or lower, or -80°C or higher, -75°C or higher, -70°C or higher, or -65°C or higher, from the viewpoint of suppressing structural changes in the solid electrolyte.

[0063] The time when moisture is attached to the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer is not particularly limited, but it may be 1 second or longer, 10 seconds or longer, 30 seconds or longer, 1 minute or longer, 10 minutes or longer, 30 minutes or longer, or 1 hour or longer, or 5 hours or shorter, 3 hours or shorter, 1 hour or shorter, or 30 minutes or shorter.

[0064] (Lamination Method) As a method for laminating a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer, specifically, for example, on each surface of the negative electrode active material layer formed on both surfaces of a negative electrode current collector, the solid electrolyte layer formed on a substrate is respectively overlaid and pressed, the solid electrolyte layer is transferred onto the surface of the negative electrode active material layer, the substrate in contact with the solid electrolyte layer is peeled off, the solid electrolyte layer is laminated on the negative electrode active material layer, and then, on each surface of the solid electrolyte layer laminated on both surfaces of the negative electrode active material layer, the positive electrode active material layer formed on a substrate is respectively overlaid and pressed, the positive electrode active material layer is transferred onto the surface of the solid electrolyte layer, the substrate in contact with the positive electrode active material layer is peeled off, and the positive electrode active material layer can be laminated on the solid electrolyte layer, but it is not limited to this case.

[0065] The above laminate may be used as a solid battery, or a positive electrode current collector layer and / or a negative electrode current collector layer may be provided on the laminate in which the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer are laminated, and it may be laminated and encapsulated to form a solid battery. The solid battery is not particularly limited, but for example, it may be constrained by a constraint pressure of 5 MPa.

Examples

[0066] The present disclosure will be described in more detail with reference to the examples shown below, but the scope of the present disclosure is not limited to these examples.

[0067] 〈Water content of positive electrode active material layer, solid electrolyte layer, negative electrode active material layer, and densified laminate〉 The water content of each of the above layers and the above laminate was measured using a Karl Fischer apparatus (Karl Fischer apparatus CA-310 and moisture vaporization apparatus VA-300 manufactured by Nitto Seiko). Specifically, the measurement sample was heated to 200 °C by the moisture vaporization apparatus VA-300, and the moisture generated by the heating was measured by the Karl Fischer apparatus CA-310 to obtain the water content.

[0068] 〈Hydroxyl group standard value of positive electrode active material layer, solid electrolyte layer, and negative electrode active material layer〉 The hydroxyl group standard value of the positive electrode active material layer was determined by Fourier transform infrared spectroscopy (FT-IR) at 3300 cm of the positive electrode active material layer ―1The absorbance at ―1 and the absorbance at 1180 cm -1 were measured, and the ratio of the absorbance at 3300 cm -1 to the absorbance at 1180 cm was calculated as the hydroxyl group standard value of the positive electrode active material layer. The hydroxyl group standard values of the solid electrolyte layer and the negative electrode active material layer were also determined in the same manner as the hydroxyl group standard value of the positive electrode active material layer.

[0069] 《Example 1》 〈Fabrication of Positive Electrode Active Material Layer A1〉 LiNi coated with a Li-Ti-Al-F-based material as a positive electrode active material 0.8 (CoAl) 0.2 O2, Li2S-P2S5-based glass ceramics as a solid electrolyte, conductive carbon as a conductive aid, a binder, a dispersant, and an appropriate amount of a solvent were mixed and dispersed by an ultrasonic homogenizer to prepare a positive electrode composite slurry. Next, the obtained positive electrode composite slurry was coated on an aluminum foil by die coating, dried, and a positive electrode active material layer was formed on one side of the aluminum foil. The obtained positive electrode active material layer was left standing in a humidity-controlled glove box set at a dew point of -60°C for a predetermined time to adsorb moisture, and a positive electrode active material layer A1 with a moisture content of 101 ppm and a hydroxyl group standard value of 0.65 was obtained.

[0070] 〈Fabrication of Solid Electrolyte Layer B1〉 LiI-LiBr-Li2S-P2S5-based glass ceramics (average particle size 2.5 μm) as a solid electrolyte, conductive carbon as a conductive aid, a binder, a dispersant, and an appropriate amount of a solvent were mixed and dispersed by an ultrasonic homogenizer to prepare a solid electrolyte composite slurry. Next, the obtained solid electrolyte composite slurry was coated on an aluminum foil by die coating, dried, and a solid electrolyte layer was formed on one side of the aluminum foil. The obtained solid electrolyte layer was left standing in a humidity-controlled glove box set at a dew point of -60°C for a predetermined time to adsorb moisture, and a solid electrolyte layer B1 with a moisture content of 979 ppm and a hydroxyl group standard value of 0.74 was obtained.

[0071] 〈Fabrication of Negative Electrode Active Material Layer C1〉 Li4Ti5O as a negative electrode active material 12 Particles, Li2S-P2S5-based glass ceramics as a solid electrolyte, conductive carbon as a conductive aid, a binder, a dispersant, and an appropriate amount of a solvent were mixed and dispersed by an ultrasonic homogenizer to prepare a negative electrode composite slurry. Next, the obtained negative electrode composite slurry was applied onto an aluminum foil as a negative electrode current collector by die coating, dried, and a negative electrode active material layer was formed on one side of the aluminum foil. Then, the negative electrode composite slurry was applied onto the surface of the aluminum foil where the negative electrode active material layer was not formed by die coating, dried, and thereby negative electrode active material layers were formed on both sides of the aluminum foil. The obtained negative electrode active material layer was left standing in a humidity-controlled glove box set at a dew point of -60°C for a predetermined time to adsorb moisture, and a negative electrode active material layer C1 with adsorbed moisture was obtained. The moisture content of the negative electrode active material layer C1 was 410 ppm, and the hydroxyl group standard value was 0.68. Here, the basis weight of the negative electrode active material layer was adjusted so that the charge specific capacity of the negative electrode active material layer was 1 times that of the positive electrode active material layer when the charge specific capacity of the positive electrode active material layer was 200 mAh / g.

[0072] <Fabrication of Dense Laminate D1> On each surface of the negative electrode active material layer C1 formed on both sides of an aluminum foil as a negative electrode current collector, a solid electrolyte layer B1 was respectively overlaid and pressed, and the solid electrolyte layer B1 was transferred onto the surface of the negative electrode active material layer C1. The aluminum foil in contact with the solid electrolyte layer B1 was peeled off, and the solid electrolyte layer B1 was laminated on the negative electrode active material layer C1. Next, on each surface of the solid electrolyte layer B1 laminated on both sides of the negative electrode active material layer C1, a positive electrode active material layer A1 was respectively overlaid and pressed, and the positive electrode active material layer A1 was transferred onto the surface of the solid electrolyte layer B1. The aluminum foil in contact with the positive electrode active material layer A1 was peeled off, and the positive electrode active material layer A1 was laminated on the solid electrolyte layer B1. The fabricated laminate was roll-pressed at 175°C and 5 ton / cm to fabricate a dense laminate D1.

[0073] <Fabrication of Solid Battery E1> On the surface of each of the positive electrode active material layers A1 of the densified laminate D1, a carbon-coated aluminum foil as a positive electrode current collector was disposed, and pressed at 140 °C and 5 MPa for 5 minutes to obtain a power generation element. Here, the power generation element had a positive electrode current collector layer, a positive electrode active material layer A1, a solid electrolyte layer B1, a negative electrode active material layer C1, a negative electrode current collector layer, a negative electrode active material layer C1, a solid electrolyte layer B1, a positive electrode active material layer A1, and a positive electrode current collector layer laminated in this order. The obtained power generation element was laminated and encapsulated, and constrained at 5 MPa to fabricate a solid battery E1.

[0074] 〈Rate of increase in resistance of solid battery E1〉 For the solid battery E1, constant current charging was performed at 0.3C equivalent until a voltage corresponding to a 40% depth of charge was reached, and then constant voltage charging was performed until a current of 0.01C was reached. Thereafter, the solid battery E1 was placed in a thermostat set at 60 °C and stored for 2 weeks. The DC resistance was measured before and after storage in the thermostat, and the difference between the value of the DC resistance after storage and the value of the DC resistance before storage was divided by the value of the DC resistance before storage and multiplied by 100 to calculate the rate of increase in resistance (%) before and after storage (Rate of increase in resistance (%) = (DC resistance after storage (Ω) - DC resistance before storage (Ω)) / DC resistance before storage (Ω) × 100). The rate of increase in resistance of the solid battery E1 was -2.51%. The value of the DC resistance was calculated by discharging the solid battery E1 charged at 0.3C equivalent until a voltage corresponding to a 40% depth of charge was reached and then charged at a constant voltage until a current of 0.01C was reached, at 72C equivalent constant current discharge, and dividing the difference between the voltage before discharge and the voltage after 0.1 second of discharge by the current amount equivalent to 72C (DC resistance (Ω) = (Voltage before discharge (V) - Voltage after 0.1 second of discharge (V)) / Current amount equivalent to 72C (A)).

[0075] 《Examples 2 to 16》 In the same manner as in Example 1, positive electrode active material layers, solid electrolyte layers, and negative electrode active material layers having the moisture content and hydroxyl group standard values shown in Tables 1 and 2 were fabricated. Next, in the same manner as in Example 1, solid batteries shown in Tables 1 and 2 were fabricated using the above positive electrode active material layers, solid electrolyte layers, and negative electrode active material layers. Also, the rate of increase in resistance of each solid battery was determined in the same manner as in Example 1. The rate of increase in resistance of each solid battery was as shown in Tables 1 and 2.

[0076] Comparative Example 1 <Preparation of the positive electrode active material layer A3> In the same manner as in Example 1, a positive electrode active material layer was formed, and the obtained positive electrode active material layer was allowed to stand in a humidity-controlled glove box set at a dew point of -60°C for 15 minutes to adsorb moisture, thereby obtaining a positive electrode active material layer A3. The moisture content and hydroxyl group standard value of the positive electrode active material layer A3 were as shown in Table 3.

[0077] <Preparation of the solid electrolyte layer B4> In the same manner as in Example 1, a solid electrolyte layer was formed, and the obtained solid electrolyte layer was allowed to stand in a humidity-controlled glove box set at a dew point of -60°C for 15 minutes to adsorb moisture, thereby obtaining a solid electrolyte layer B4. The moisture content and hydroxyl group standard value of the solid electrolyte layer B4 were as shown in Table 3.

[0078] <Preparation of the negative electrode active material layer C5> In the same manner as in Example 1, a negative electrode active material layer was formed, and the obtained negative electrode active material layer was allowed to stand in a humidity-controlled glove box set at a dew point of -60°C for 15 minutes to adsorb moisture, thereby obtaining a negative electrode active material layer C5. The moisture content and hydroxyl group standard value of the negative electrode active material layer C5 were as shown in Table 3.

[0079] <Preparation of the solid battery e1 and the resistance increase rate of the solid battery e1> A solid battery e1 was fabricated in the same manner as in Example 1, except that the positive electrode active material layer A3 was used instead of the positive electrode active material layer A1, the solid electrolyte layer B4 was used instead of the solid electrolyte layer B1, and the negative electrode active material layer C5 was used instead of the negative electrode active material layer C1. Also, the resistance increase rate of the solid battery e1 was determined in the same manner as in Example 1. The resistance increase rate of the solid battery e1 was as shown in Table 3.

[0080] Comparative Example 2 <Preparation of the positive electrode active material layer A4> The obtained positive electrode active material layer was left standing in a humidity-controlled glove box set at a dew point of -60°C for 30 minutes, and a positive electrode active material layer A4 adsorbed with moisture was produced in the same manner as in Comparative Example 1. The moisture content and hydroxyl group standard value of the positive electrode active material layer A4 were as shown in Table 3.

[0081] <Production of Solid Electrolyte Layer B5> The obtained solid electrolyte layer was left standing in a humidity-controlled glove box set at a dew point of -60°C for 30 minutes, and a solid electrolyte layer B5 adsorbed with moisture was produced in the same manner as in Comparative Example 1. The moisture content and hydroxyl group standard value of the solid electrolyte layer B5 were as shown in Table 3.

[0082] <Production of Negative Electrode Active Material Layer C6> The obtained negative electrode active material layer was left standing in a humidity-controlled glove box set at a dew point of -60°C for 30 minutes, and a negative electrode active material layer C6 adsorbed with moisture was produced in the same manner as in Comparative Example 1. The moisture content and hydroxyl group standard value of the negative electrode active material layer C6 were as shown in Table 3.

[0083] <Production of Solid State Battery e2 and Rate of Resistance Increase of Solid State Battery e2> A solid state battery e2 was produced in the same manner as in Example 1, except that the positive electrode active material layer A4 was used instead of the positive electrode active material layer A1, the solid electrolyte layer B5 was used instead of the solid electrolyte layer B1, and the negative electrode active material layer C6 was used instead of the negative electrode active material layer C1. Also, the rate of resistance increase of the solid state battery e2 was determined in the same manner as in Example 1. The rate of resistance increase of the solid state battery e2 was as shown in Table 3.

[0084] <<Comparative Example 3>> <Production of Positive Electrode Active Material Layer A5> A positive electrode active material layer A5 was formed on the surface of an aluminum foil in the same manner as in Example 1. Note that the positive electrode active material layer A5 was not left standing in a humidity-controlled glove box set at a dew point of -60°C, and intentional moisture adsorption was not performed.

[0085] <Production of Solid Electrolyte Layer B6> In the same manner as in Example 1, a solid electrolyte layer B6 was formed on the surface of the aluminum foil. Note that the solid electrolyte layer B6 was not left standing in a humidity-controlled glove box set at a dew point of -60°C, and no intentional moisture adsorption was performed.

[0086] <Fabrication of the negative electrode active material layer C7> In the same manner as in Example 1, a negative electrode active material layer C7 was formed on both sides of the aluminum foil. Note that the negative electrode active material layer C7 was not left standing in a humidity-controlled glove box set at a dew point of -60°C, and no intentional moisture adsorption was performed.

[0087] <Fabrication of the densified laminate d3> A densified laminate was fabricated in the same manner as in Example 1, except that the positive electrode active material layer A5 was used instead of the positive electrode active material layer A1, the solid electrolyte layer B6 was used instead of the solid electrolyte layer B1, and the negative electrode active material layer C7 was used instead of the negative electrode active material layer C1. The obtained densified laminate was left standing in a humidity-controlled glove box set at a dew point of -60°C for 15 minutes to obtain a densified laminate d3 with adsorbed moisture. The moisture content of the densified laminate d3 was as shown in Table 3.

[0088] <Fabrication of the solid battery e3 and the resistance increase rate of the solid battery e3> A solid battery e3 was fabricated in the same manner as in Example 1, except that the densified laminate d3 was used instead of the densified laminate D1. Also, the resistance increase rate of the solid battery e3 was determined in the same manner as in Example 1. The resistance increase rate of the solid battery e3 was as shown in Table 3.

[0089] <<Comparative Example 4>> <Fabrication of the densified laminate d4> A densified laminate d4 with adsorbed moisture was fabricated in the same manner as in Comparative Example 3, except that the obtained densified laminate was left standing in a humidity-controlled glove box set at a dew point of -60°C for 30 minutes. The moisture content of the densified laminate d4 was as shown in Table 3.

[0090] <Fabrication of the solid battery e4 and the resistance increase rate of the solid battery e4> A solid battery e4 was fabricated in the same manner as in Example 1, except that the densified laminate d4 was used instead of the densified laminate D1. Also, the resistance increase rate of the solid battery e4 was determined in the same manner as in Example 1. The resistance increase rate of the solid battery e4 was as shown in Table 3.

[0091]

Table 1

[0092]

Table 2

[0093]

Table 3

[0094] 《Example 17》 〈Fabrication of the positive electrode active material layer A6〉 The positive electrode active material layer A6 was fabricated in the same manner as in Example 1, except that it was placed in a humidity-controlled glove box set at a dew point of -60°C and left standing for 60 minutes.

[0095] 〈Ratio of physically adsorbed water to the water content in the positive electrode active material layer A6〉 For the positive electrode active material layer A6, measurement was carried out by temperature-programmed desorption mass spectrometry (TPD-MS) under the conditions of a measurement temperature of 30 to 500°C and a heating rate of 10°C / min to obtain the generation rate curve of water (m / z = 18). Next, the amount of water generated when the temperature was raised to 100°C was calculated as the amount of physically adsorbed water from the peak area of the water generation rate curve in the measurement temperature range of 30 to 100°C. Similarly, the amount of water generated when the temperature was raised to 120°C was calculated as the amount of water contained in the positive electrode active material layer from the peak area of the water generation rate curve in the measurement temperature range of 30 to 120°C. The ratio of the amount of physically adsorbed water to the amount of water contained in the positive electrode active material layer A6 was 0.70.

[0096] 《Example 18》 <Production of the positive electrode active material layer A7 and ratio of physically adsorbed water to the water contained in the positive electrode active material layer A7> The positive electrode active material layer A7 was produced in the same manner as in Example 1, except that it was placed in a humidity-controlled glove box set at a dew point of -50°C and allowed to stand for 60 minutes. The ratio of physically adsorbed water to the water contained in the positive electrode active material layer A7 was determined in the same manner as in Example 17, and the measurement results are shown in Table 4.

[0097] [Table 4]

[0098] In Examples 1 to 16, a predetermined amount of water was adsorbed to the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer, respectively, and a solid battery was fabricated using them, and the resistance increase rate was evaluated. On the other hand, in Comparative Examples 1 and 2, water was uniformly adsorbed to the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer under the same conditions, and a solid battery was fabricated using them, and the resistance increase rate was evaluated. In Comparative Examples 3 and 4, water was uniformly adsorbed to the densified laminate, and a solid battery was fabricated using the densified laminate adsorbed with water, and the resistance increase rate was evaluated. It was confirmed that the increase in the resistance of the obtained solid battery can be suppressed by adsorbing a predetermined amount of water to the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer, respectively, rather than uniformly adsorbing water to all the layers or laminates under the same conditions.

[0099] In Examples 16 and 17, the water adsorbed to the positive electrode active material layer was analyzed. When the positive electrode active material layer was adsorbed with water in a low dew point environment (dew points of -60°C and -50°C), it was confirmed that the amount of physically adsorbed water in the positive electrode active material layer was 0.5 to 0.9 with respect to the amount of water contained in the positive electrode active material layer, that is, the positive electrode active material layer contained a large amount of physically adsorbed water.

[0100] Although the details are not clear, a predetermined amount of moisture adsorbed in the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer, particularly the physically adsorbed water contained in a large amount in the positive electrode active material layer, penetrates to the interface between the positive electrode active material layer and the solid electrolyte layer, and a reaction layer having an appropriate thickness is formed at this interface. It is presumed that the oxidative decomposition of the solid electrolyte during charging is suppressed by this reaction layer, thereby suppressing an increase in resistance.

[0101] Although the preferred embodiments of the solid battery and the method for manufacturing the solid battery of the present disclosure have been described, those skilled in the art understand that changes can be made without departing from the scope of the claims.

Explanation of Signs

[0102] 100 Solid battery 110 Positive electrode active material layer 120 Solid electrolyte layer 130 Negative electrode active material layer

Claims

1. A solid battery having a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in this order, wherein the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer contain moisture, and (i) the moisture content of the positive electrode active material layer is 100 to 350 ppm, the moisture content of the solid electrolyte layer is 500 to 1400 ppm, and the moisture content of the negative electrode active material layer is 400 to 1200 ppm, and / or and (ii) the hydroxyl group standard value of the positive electrode active material layer is 0.63 to 0.71, the hydroxyl group standard value of the solid electrolyte layer is 0.61 to 0.85, and the hydroxyl group standard value of the negative electrode active material layer is 0.66 to 2.

85. A solid battery.

2. The solid battery according to claim 1, wherein the solid electrolyte layer contains a sulfide solid electrolyte.

3. A part of the moisture contained in the positive electrode active material layer is physically adsorbed water physically adsorbed on the positive electrode active material layer, and the moisture content of the physically adsorbed water is 0.50 to 0.90 with respect to the moisture content of the positive electrode active material layer. The solid battery according to claim 1.

4. A method for manufacturing a solid battery according to any one of claims 1 to 3, comprising the following steps: adsorbing moisture on the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer in an environment with a dew point of 0 °C or lower, and stacking the positive electrode active material layer adsorbed with moisture, the solid electrolyte layer adsorbed with moisture, and the negative electrode active material layer adsorbed with moisture in this order to obtain a solid battery.

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