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 and the solid electrolyte layer 120 contain moisture. (i) The moisture content of the positive electrode active material layer 110 is from 100 to 350 ppm, and the moisture content of the solid electrolyte layer 120 is from 1500 to 2000 ppm. (ii) And / or the hydroxyl group standard value of the positive electrode active material layer 110 is from 0.63 to 0.71, and the hydroxyl group standard value of the solid electrolyte layer 120 is from 0.87 to 1.04.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 to improve it. 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 and the solid electrolyte layer, respectively, rather than the entire electrode laminate, and about the 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 and the solid electrolyte layer contain moisture, (i) the moisture content of the positive electrode active material layer is 100 to 350 ppm, and the moisture content of the solid electrolyte layer is 1500 to 2000 ppm, and / or (ii) the hydroxyl group standard value of the positive electrode active material layer is 0.63 to 0.71, and the hydroxyl group standard value of the solid electrolyte layer is 0.87 to 1.04. Solid battery. 〈Aspect 2〉 wherein the moisture content of the negative electrode active material layer is 300 ppm or less, and / or the hydroxyl group standard value of the negative electrode active material layer is 0.37 or less. The solid battery according to Aspect 1. 〈Aspect 3〉 The solid battery according to Aspect 1 or 2, wherein the solid electrolyte layer contains a sulfide solid electrolyte. 〈Aspect 4〉 wherein 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 any one of Aspects 1 to 3. 〈Aspect 5〉 A method for manufacturing the solid battery according to any one of Aspects 1 to 4, including the following steps: adsorbing moisture to the positive electrode active material layer and the solid electrolyte layer respectively 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 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 reference numerals are given to the same elements, and duplicate 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 an 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 an 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 and the above solid electrolyte layer contain moisture, (i) the moisture content of the above positive electrode active material layer is 100 to 350 ppm, and the moisture content of the above solid electrolyte layer is 1500 to 2000 ppm, and / or (ii) The hydroxyl group standard value of the positive electrode active material layer is 0.63 to 0.71, and the hydroxyl group standard value of the solid electrolyte layer is 0.87 to 1.04.

[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 on the positive electrode active material layer and the solid electrolyte 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 embodiment 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 the positive electrode active material layer 110 and the solid electrolyte layer 120 contain a predetermined amount of moisture. An increase in the resistance of the solid battery can be suppressed by the predetermined amount of moisture contained in the positive electrode active material layer 110 and the solid electrolyte layer 120.

[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, and generally used materials for 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. Further, the positive electrode current collector layer may have some coating layer on its surface for the purpose of adjusting resistance or the like. Also, the positive electrode current collector layer may be a metal foil or a substrate on which the above-mentioned metal is plated or vapor-deposited.

[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, conductive assistant, binder, etc. in the positive electrode active material layer may be appropriately determined according to the target battery performance. For example, assuming the total of the positive electrode active material layer (total solid content) is 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] (Moisture 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 a 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. 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 with the Karl Fischer apparatus CA-310 to obtain the moisture content.

[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 a 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. 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 on the positive electrode active material layer, although it is not particularly limited. The amount of moisture of the 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 moisture of the 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 moisture of the 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 moisture of the physically adsorbed water, the amount of moisture 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 moisture 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 moisture of the 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 cobalt oxide (LiCoO2), lithium nickel oxide (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 hetero - element - substituted Li - Mn spinel having a composition represented thereby, but is not limited thereto.

[0028] The positive electrode active material is not particularly limited, but may have a coating layer. The coating layer contains a substance that has lithium ion conduction performance, low reactivity with the positive electrode active material and the solid electrolyte, and can maintain the form of the coating layer without flowing 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 the 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 50% of the integrated value 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., can be mentioned, 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 1500 to 2000 ppm. From the perspective of forming the reaction layer, the moisture content of the solid electrolyte layer may be 1500 ppm or more, 1600 ppm or more, 1700 ppm or more, 1800 ppm or more, or 1900 ppm or more, and from the perspective of suppressing hydrolysis of the solid electrolyte, it may be 2000 ppm or less, or 1950 ppm or less. Regarding 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 0.87 to 1.04. From the perspective of forming the reaction layer, the hydroxyl group standard value of the solid electrolyte layer may be 0.87 or more, 0.90 or more, 0.95 or more, or 1.00 or more, and from the perspective of suppressing hydrolysis of the solid electrolyte, it may be 1.04 or less, 1.03 or less, or 1.02 or less. Regarding 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] Regarding 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 dry or wet molding of a solid electrolyte composite material containing the above-mentioned solid electrolyte and binder.

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

[0046] (Water content of the negative electrode active material layer) The water content of the negative electrode active material layer is not particularly limited, but may be 300 ppm or less. Also, the water content of the negative electrode active material layer may be 150 ppm or more, 160 ppm or more, 170 ppm or more, 180 ppm or more, 190 ppm or more, or 200 ppm or more, and may also be 300 ppm or less, 280 ppm or less, 260 ppm or less, 240 ppm or less, or 220 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 negative electrode active material layer) The hydroxyl group standard value of the negative electrode active material layer is not particularly limited, but may be 0.37 or less. Also, the hydroxyl group standard value of the negative electrode active material layer may be 0.01 or more, 0.02 or more, 0.04 or more, 0.06 or more, or 0.08 or more, and may also be 0.37 or less, 0.31 or less, 0.25 or less, 0.19 or less, or 0.13 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 employed. 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 the material 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. In addition, 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. In addition, 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 it 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 assistant, 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 known methods. 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 employed. Examples of the material used for the negative electrode current collector layer include, but are not limited to, Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, stainless steel, or a carbon sheet. 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. 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 the solid battery, etc.〉 Examples of the shape of the solid battery include, but are not limited to, coin type, laminate type, cylindrical type, and rectangular type.

[0059] 《Manufacturing method of the 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 to the positive electrode active material layer and the solid electrolyte layer respectively, and obtaining a solid-state battery by laminating the positive electrode active material layer adsorbed with moisture, the solid electrolyte layer adsorbed with moisture, and the negative electrode active material layer 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 of adsorbing moisture) As a method of adsorbing moisture to 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 is 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 of adsorbing moisture to the solid electrolyte layer is the same as that of the positive electrode active material layer.

[0062] The dew point of the environment for attaching moisture to the positive electrode active material layer and the solid electrolyte 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 for attaching moisture to the positive electrode active material layer and the solid electrolyte 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] (Laminating method) As a method for laminating the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer, specifically, for example, on each surface of the negative electrode active material layer formed on both sides of the negative electrode current collector, the solid electrolyte layer formed on the base material is respectively overlapped and pressed, the solid electrolyte layer is transferred to the surface of the negative electrode active material layer, the base material 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 sides of the negative electrode active material layer, the positive electrode active material layer formed on the base material is respectively overlapped and pressed, the positive electrode active material layer is transferred to the surface of the solid electrolyte layer, the base material 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 sealed 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 the 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 the positive electrode active material layer and the solid electrolyte 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 value of the solid electrolyte layer was also determined in the same manner as that 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. Subsequently, the obtained positive electrode composite slurry was applied onto 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. Subsequently, the obtained solid electrolyte composite slurry was applied onto 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 1515 ppm and a hydroxyl group standard value of 0.89 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. Thereafter, 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 a negative electrode active material layer C1 was formed on both sides of the aluminum foil. Note that the negative electrode active material layer C1 was not left standing in a humidity control glove box set at a dew point of -60°C, and intentional moisture adsorption was not performed. The moisture content of the negative electrode active material layer C1 was 205 ppm, and the hydroxyl group standard value was 0.09. 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 time 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] <Production of Dense Laminate D1> On each surface of the negative electrode active material layer C1 formed on both sides of the aluminum foil as a negative electrode current collector, a solid electrolyte layer B1 was superposed and pressed respectively, the solid electrolyte layer B1 was transferred onto the surface of the negative electrode active material layer C1, and the aluminum foil in contact with the solid electrolyte layer B1 was peeled off to laminate the solid electrolyte layer B1 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 superposed and pressed respectively, the positive electrode active material layer A1 was transferred onto the surface of the solid electrolyte layer B1, and the aluminum foil in contact with the positive electrode active material layer A1 was peeled off to laminate the positive electrode active material layer A1 on the solid electrolyte layer B1. The produced laminate was roll-pressed at 175°C and 5 ton / cm to produce a dense laminate D1.

[0073] <Production of Solid Battery E1> On each surface of the positive electrode active material layer A1 of the densified laminate D1, a carbon-coated aluminum foil as a positive electrode current collector was placed 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 carried out at 0.3C equivalent until a voltage equivalent to a 40% depth of charge was reached, and then constant voltage charging was carried out until a current of 0.01C was reached. Thereafter, the solid battery E1 was placed in a thermostatic chamber set at 60 °C and stored for 2 weeks. The DC resistance was measured before and after storage in the thermostatic chamber, 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 equivalent to a 40% depth of charge was reached and then charged at a constant voltage until a current of 0.01C was reached at a constant current of 72C equivalent, 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] 《Example 2》 〈Fabrication of solid electrolyte layer B2〉 In the same manner as in Example 1, a solid electrolyte layer was formed, and 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, obtaining a solid electrolyte layer B2. The moisture content and hydroxyl group standard value of the solid electrolyte layer B2 were as shown in Table 1.

[0076] <Production of Solid Battery E2 and Rate of Resistance Increase of Solid Battery E2> A solid battery E2 was produced in the same manner as in Example 1, except that a solid electrolyte layer B2 was used instead of the solid electrolyte layer B1. Also, the rate of resistance increase of the solid battery E2 was determined in the same manner as in Example 1. The rate of resistance increase of the solid battery E2 was as shown in Table 1.

[0077] <<Example 3>> <Production of Cathode Active Material Layer A2> A cathode active material layer was formed in the same manner as in Example 1, and the obtained cathode active material layer was allowed to stand in a humidity-controlled glove box set at a dew point of -60°C for a predetermined time to obtain a cathode active material layer A2 adsorbed with moisture. The moisture content and hydroxyl group standard value of the cathode active material layer A2 were as shown in Table 1.

[0078] <Production of Solid Battery E3 and Rate of Resistance Increase of Solid Battery E3> A solid battery E3 was produced in the same manner as in Example 1, except that a cathode active material layer A2 was used instead of the cathode active material layer A1. Also, the rate of resistance increase of the solid battery E3 was determined in the same manner as in Example 1. The rate of resistance increase of the solid battery E3 was as shown in Table 1.

[0079] <<Example 4>> <Production of Solid Battery E4 and Rate of Resistance Increase of Solid Battery E4> A solid battery E4 was produced in the same manner as in Example 1, except that a cathode active material layer A2 was used instead of the cathode active material layer A1 and a solid electrolyte layer B2 was used instead of the solid electrolyte layer B1. Also, the rate of resistance increase of the solid battery E4 was determined in the same manner as in Example 1. The rate of resistance increase of the solid battery E4 was as shown in Table 1.

[0080] <<Comparative Example 1>> <Production of Cathode Active Material Layer A3> A cathode active material layer was formed in the same manner as in Example 1, and the obtained cathode 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 obtain a cathode active material layer A3 adsorbed with moisture. The moisture content and hydroxyl group standard value of the cathode active material layer A3 were as shown in Table 2.

[0081] <Fabrication of Solid Electrolyte Layer B3> In the same manner as in Example 1, a solid electrolyte layer was formed, and the obtained solid electrolyte layer was left standing in a humidity-controlled glove box set at a dew point of -60°C for 15 minutes to obtain a solid electrolyte layer B3 adsorbed with moisture. The moisture content and hydroxyl group standard value of the solid electrolyte layer B3 were as shown in Table 2.

[0082] <Fabrication of Negative Electrode Active Material Layer C2> 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 left standing in a humidity-controlled glove box set at a dew point of -60°C for 15 minutes to obtain a negative electrode active material layer C2 adsorbed with moisture. The moisture content and hydroxyl group standard value of the negative electrode active material layer C2 were as shown in Table 2.

[0083] <Fabrication of Solid State Battery e1 and Rate of Resistance Increase of Solid State Battery e1> A solid state battery e1 was fabricated in the same manner as in Example 1, except that a positive electrode active material layer A3 was used instead of the positive electrode active material layer A1, a solid electrolyte layer B3 was used instead of the solid electrolyte layer B1, and a negative electrode active material layer C2 was used instead of the negative electrode active material layer C1. Also, the rate of resistance increase of the solid state battery e1 was determined in the same manner as in Example 1. The rate of resistance increase of the solid state battery e1 was as shown in Table 2.

[0084] <<Comparative Example 2>> <Fabrication of Positive Electrode Active Material Layer A4> A positive electrode active material layer A4 adsorbed with moisture was fabricated in the same manner as in Comparative Example 1, except that 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. The moisture content and hydroxyl group standard value of the positive electrode active material layer A4 were as shown in Table 2.

[0085] <Fabrication of Solid Electrolyte Layer B4> A solid electrolyte layer B4 adsorbed with moisture was fabricated in the same manner as in Comparative Example 1, except that 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. The moisture content and hydroxyl group standard value of the solid electrolyte layer B4 were as shown in Table 2.

[0086] <Production of the negative electrode active material layer C3> A negative electrode active material layer C3 adsorbed with moisture was produced in the same manner as in Comparative Example 1, except that 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 30 minutes. The moisture content and hydroxyl group standard value of the negative electrode active material layer C3 were as shown in Table 2.

[0087] <Production of the solid-state battery e2 and rate of increase in resistance of the 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 B4 was used instead of the solid electrolyte layer B1, and the negative electrode active material layer C3 was used instead of the negative electrode active material layer C1. Also, the rate of increase in resistance of the solid-state battery e2 was determined in the same manner as in Example 1. The rate of increase in resistance of the solid-state battery e2 was as shown in Table 2.

[0088] <<Comparative Example 3>> <Production of the positive electrode active material layer A5> The positive electrode active material layer A5 was formed on the surface of the aluminum foil in the same manner as in Example 1. Note that the positive electrode active material layer A5 was not allowed to stand in a humidity-controlled glove box set at a dew point of -60°C, and no intentional moisture adsorption was performed.

[0089] <Production of the solid electrolyte layer B5> The solid electrolyte layer B5 was formed on the surface of the aluminum foil in the same manner as in Example 1. Note that the solid electrolyte layer B5 was not allowed to stand in a humidity-controlled glove box set at a dew point of -60°C, and no intentional moisture adsorption was performed.

[0090] <Production of the densified laminate d3> A densified laminate was produced 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 and the solid electrolyte layer B5 was used instead of the solid electrolyte layer B1. The obtained densified laminate was allowed to stand in a humidity-controlled glove box set at a dew point of -60°C for 15 minutes to obtain a densified laminate d3 adsorbed with moisture. The moisture content of the densified laminate d3 was as shown in Table 2.

[0091] <Production of Solid Battery e3 and Rate of Resistance Increase of Solid Battery e3> A solid battery e3 was produced in the same manner as in Example 1, except that a densified laminate d3 was used instead of the densified laminate D1. Also, the rate of resistance increase of the solid battery e3 was determined in the same manner as in Example 1. The rate of resistance increase of the solid battery e3 was as shown in Table 2.

[0092] <<Comparative Example 4>> <Production of Densified Laminate d4> A densified laminate d4 adsorbed with moisture was produced 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 2.

[0093] <Production of Solid Battery e4 and Rate of Resistance Increase of Solid Battery e4> A solid battery e4 was produced in the same manner as in Example 1, except that a densified laminate d4 was used instead of the densified laminate D1. Also, the rate of resistance increase of the solid battery e4 was determined in the same manner as in Example 1. The rate of resistance increase of the solid battery e4 was as shown in Table 2.

[0094] Tables 1 and 2 show the moisture content, hydroxyl group standard value, and rate of resistance increase of each layer of the solid battery.

[0095] <>

[0096] <>

[0097] <<Example 5>> <Production of Cathode Active Material Layer A6> A cathode active material layer A6 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 -60°C and left standing for 60 minutes.

[0098] <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, by thermogravimetric analysis coupled with mass spectrometry (TPD-MS), the generation rate curve of water (m / z = 18) was obtained under the conditions of a measurement temperature of 30 to 500 °C and a heating rate of 10 °C / min. Subsequently, 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 generation rate curve of water in the 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 water content in the positive electrode active material layer from the peak area of the generation rate curve of water in the temperature range of 30 to 120 °C. The ratio of the amount of physically adsorbed water to the water content in the positive electrode active material layer A6 was 0.70.

[0099] <<Example 6>> <Production of the positive electrode active material layer A7 and ratio of physically adsorbed water to the water content in the positive electrode active material layer A7> The positive electrode active material layer prepared in the same manner as in Example 1 was placed in a humidity-controlled glove box set at a dew point of -50 °C and allowed to stand for 60 minutes to adsorb moisture, obtaining the positive electrode active material layer A7. In the same manner as in Example 5, the ratio of physically adsorbed water to the water content in the positive electrode active material layer A7 was determined, and the measurement results are shown in Table 3.

[0100] [[Table 3]]

[0101] In Examples 1 to 4, a predetermined amount of moisture was adsorbed to the positive electrode active material layer and the solid electrolyte 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, moisture 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. Further, in Comparative Examples 3 and 4, moisture was uniformly adsorbed to the densified laminate, and a solid battery was fabricated using the densified laminate adsorbed with moisture, 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 moisture to the positive electrode active material layer and the solid electrolyte layer, respectively, rather than uniformly adsorbing moisture to all the layers or laminates under the same conditions.

[0102] In Examples 5 and 6, the moisture adsorbed to the positive electrode active material layer was analyzed. When the positive electrode active material layer was adsorbed with moisture 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 moisture contained in the positive electrode active material layer, that is, the positive electrode active material layer contained a large amount of physically adsorbed water.

[0103] Although the details are not clear, a predetermined amount of moisture adsorbed to the positive electrode active material layer and the solid electrolyte 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 the increase in resistance.

[0104] 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 will understand that changes can be made without departing from the scope of the claims.

Description of Reference Numerals

[0105] 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 and the solid electrolyte layer contain moisture, and (i) the moisture content of the positive electrode active material layer is 100 to 350 ppm, and the moisture content of the solid electrolyte layer is 1500 to 2000 ppm, and / or and (ii) the hydroxyl group standard value of the positive electrode active material layer is 0.63 to 0.71, and the hydroxyl group standard value of the solid electrolyte layer is 0.87 to 1.

04. Solid battery.

2. wherein the moisture content of the negative electrode active material layer is 300 ppm or less, and / or the hydroxyl group standard value of the negative electrode active material layer is 0.37 or less. The solid battery according to claim 1.

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

4. 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.

5. A method for manufacturing the solid battery according to any one of claims 1 to 4, comprising the following steps: adsorbing moisture to the positive electrode active material layer and the solid electrolyte layer respectively 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 in this order to obtain a solid battery.

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