Electrode active material layer and battery

Abstract

This disclosure provides an electrode active material layer that can improve the capacity retention rate of a battery, and a battery containing such an electrode active material layer, thereby improving the capacity retention rate. [Solution] The electrode active material layer of this disclosure comprises an electrode active material and a sulfide solid electrolyte. In the electrode active material layer of this disclosure, the peak intensity of the spectrum obtained by XPS measurement satisfies the following relation (1): 0.40≦I(163.0) / I(161.5)≦0.60 … (1) During the ceremony, I(163.0): Maximum peak intensity of 163.0 ± 1.0 eV, I(161.5): The maximum value of the peak intensity at 161.5 ± 1.0 eV. The battery 100 of this disclosure has an electrode active material layer.

Description

[Technical Field]

[0001] This disclosure relates to an electrode active material layer and a battery. [Background technology]

[0002] As disclosed in Patent Document 1, a solid-state battery containing a sulfide solid electrolyte in the electrode composite material (electrode active material layer), i.e., a sulfide solid-state battery, is known. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-167083 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In batteries, particularly solid-state sulfide batteries, there is room for improvement in terms of capacity retention.

[0005] This disclosure aims to provide an electrode active material layer that can improve the capacity retention rate of a battery, and a battery containing such an electrode active material layer, thereby improving the capacity retention rate. [Means for solving the problem]

[0006] The Disclosing Party has found that the above-mentioned problems can be solved by the following means. <Aspect 1> It comprises an electrode active material and a sulfide solid electrolyte, and The peak intensities of the spectrum obtained by XPS measurement satisfy the following relationship (1): 0.40≦I(163.0) / I(161.5)≦0.60 … (1) During the ceremony, I(163.0): Maximum peak intensity of 163.0 ± 1.0 eV, I(161.5): Maximum value of peak intensity at 161.5 ± 1.0 eV, Electrode active material layer. <Aspect 2> The electrode active material layer according to Aspect 1, wherein the electrode active material is a silicon-based electrode active material. <Aspect 3> The peak intensity of the spectrum obtained by FT-IR measurement satisfies the following relational expression (2): 0 < I(3200) / I(3400) ≤ 0.7 … (2) In the formula, I(3200): Peak intensity at 3200 ± 50 cm -1 , I(3400): Peak intensity at 3400 ± 50 cm -1 , The electrode active material layer according to Aspect 2. <Aspect 4> The electrode active material layer according to any one of Aspects 1 to 3, wherein the sulfide solid electrolyte is a Li2S-P2S5-based glass ceramic. <Aspect 5> A battery having the electrode active material layer according to any one of Aspects 1 to 4. <Aspect 6> The battery according to Aspect 5, wherein the electrode active material layer is a negative electrode active material layer. <Aspect 7> The battery according to Aspect 5 or 6, which is a solid battery.

Advantages of the Invention

[0007] According to the present disclosure, an electrode active material layer capable of improving the capacity retention rate of a battery can be provided. Further, according to the present disclosure, a battery with an improved capacity retention rate can be provided.

Brief Description of the Drawings

[0008] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of the battery of the present disclosure.

Modes for Carrying Out the Invention

[0009] The embodiments of this disclosure will be described in detail below. However, this disclosure is not limited to the embodiments described below, and can be implemented in various modified forms within the scope of the essence of the disclosure.

[0010] <<Electrode active material layer>> The electrode active material layer of this disclosure comprises an electrode active material and a sulfide solid electrolyte. In the electrode active material layer of this disclosure, the peak intensity of the spectrum obtained by XPS measurement satisfies the following relation (1): 0.40≦I(163.0) / I(161.5)≦0.60 … (1) During the ceremony, I(163.0): Maximum peak intensity of 163.0 ± 1.0 eV, I(161.5): The maximum value of the peak intensity at 161.5 ± 1.0 eV.

[0011] The disclosing parties in this case believed that one of the causes of the decrease in battery capacity retention rate was the reductive decomposition of the solid electrolyte by lithium.

[0012] In response to this, the Disclosing Party has found that the capacity retention rate of a battery containing such an electrode active material layer can be improved if the intensities of two peaks in the spectrum obtained by XPS measurement in the electrode active material layer satisfy a predetermined relation.

[0013] In the above relationship (1), I(163.0) is the peak intensity of SO, and I(161.5) is the peak intensity of SS. Therefore, I(163.0) / I(161.5), which is the ratio of SO to SS in the sulfide solid electrolyte, indicates the degree of oxidation of the sulfide solid electrolyte.

[0014] The reason why the electrode active material layer of this disclosure can improve the capacity retention rate of batteries containing it is presumed to be as follows, although this is not intended to be constrained by any theory: The two peak intensities of the spectrum obtained by XPS measurement satisfy a predetermined relationship, which suggests that the solid electrolyte is in a moderately oxidized state, specifically, the surface of the solid electrolyte is oxidized, and excessive oxidation that could lead to degradation of the solid electrolyte is suppressed. It is thought that the oxidation of the solid electrolyte surface suppresses the reductive decomposition of the solid electrolyte by lithium, thereby improving the capacity retention rate of the battery.

[0015] The following describes each element constituting the electrode active material layer of this disclosure. In this disclosure, the electrode active material layer may be a negative electrode active material layer or a positive electrode active material layer, and may be a negative electrode active material layer in particular.

[0016] <Electrode active material> The electrode active material layer of this disclosure includes an electrode active material.

[0017] With regard to this disclosure, the electrode active material may be a negative electrode active material or a positive electrode active material, and may be a negative electrode active material in particular.

[0018] The electrode active material is not particularly limited and may be, for example, a silicon-based electrode active material. The silicon-based electrode active material is not particularly limited and may be, for example, silicon, silicon oxide, silicon carbide, silicon nitride, or solid solutions thereof. Furthermore, the silicon-based electrode active material may contain elements other than silicon, such as Fe, Co, Sb, Bi, Pb, Ni, Cu, Zn, Ge, In, Sn, Ti, etc. The silicon-based electrode active material may be the negative electrode active material.

[0019] The electrode active material may be silicon in particular. The silicon is not particularly limited and may be porous silicon, for example.

[0020] As the negative electrode active material, as long as it is a material having a lower potential compared to the positive electrode active material, it is not limited to the silicon-based electrode active material described above. The negative electrode active material may be one type or a combination of two or more types.

[0021] The shape of the negative electrode active material may be, for example, particulate.

[0022] As the positive electrode active material, as long as it is a material having a higher potential compared to the negative electrode active material, it is not particularly limited. The positive electrode active material is not particularly limited. When the electrode active material layer of the present disclosure is an electrode active material layer for a lithium ion secondary battery, for example, lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganate (LiMn2O4), LiCo 1 / 3 Ni 1 / 3 Mn 1 / 3 O2, Li 1+x Mn 2-x-y heteroatom-substituted Li-Mn spinel having a composition represented by MyO4 (M is one or more metal elements selected from Al, Mg, Co, Fe, Ni, and Zn), lithium titanate (Li x TiO y ), lithium metal phosphate (LiMPO4, M is one or more metals selected from Fe, Mn, Co, and Ni), or the like, or a combination thereof may be used.

[0023] The positive electrode active material may have a coating layer. The coating layer is not particularly limited. When the electrode active material layer of the present disclosure is an electrode active material layer for a lithium ion secondary battery, it has lithium ion conduction performance, low reactivity with the positive electrode active material and the solid electrolyte, and contains a material that can maintain the form of a coating layer that does not flow even when in contact with the active material and the solid electrolyte. The material constituting the coating layer is not particularly limited, and may be, for example, LiNbO3, Li4Ti5O 12 , Li3PO4, etc.

[0024] The shape of the positive electrode active material may be, for example, particulate.

[0025] <Sulfide solid electrolyte> The electrode active material layer of this disclosure includes a sulfide solid electrolyte.

[0026] The sulfide solid electrolyte is not particularly limited and may be, for example, an amorphous sulfide solid electrolyte, a crystalline sulfide solid electrolyte, or an argyrodite-type solid electrolyte, and may be particularly an amorphous sulfide solid electrolyte.

[0027] The sulfide amorphous solid electrolyte is not particularly limited, and when the electrode active material layer of this disclosure is an electrode active material layer for a lithium-ion secondary battery, for example, a Li2S-P2S5 system (Li7P3S 11 (e.g., Li3PS4, Li8P2S9), Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-LiBr-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, etc.; or combinations thereof.

[0028] The sulfide solid electrolyte may be glass or crystallized glass (glass ceramic).

[0029] The sulfide solid electrolyte may be a Li2S-P2S5 glass ceramic in particular.

[0030] <Relationship> In the electrode active material layer of this disclosure, the peak intensity of the spectrum obtained by XPS measurement satisfies the following relation (1): 0.40≦I(163.0) / I(161.5)≦0.60 … (1) During the ceremony, I(163.0): Maximum peak intensity of 163.0 ± 1.0 eV, I(161.5): The maximum value of the peak intensity at 161.5 ± 1.0 eV.

[0031] As mentioned above, I(163.0) / I(161.5) indicates the degree of oxidation of the sulfide solid electrolyte, and the battery's capacity retention rate can be improved when the above relationship (1) is satisfied.

[0032] I(163.0) / I(161.5) may be 0.41 or greater, 0.42 or greater, 0.43 or greater, 0.44 or greater, or 0.45 or greater, and may also be 0.55 or less, 0.52 or less, 0.50 or less, 0.49 or less, 0.48 or less, or 0.47 or less. When I(163.0) / I(161.5) is within the above range, the battery capacity retention rate can be effectively improved.

[0033] XPS (X-ray photoelectron spectroscopy) measurements can be performed using ULVAC-FI's VersaprobeII. In XPS measurements, the maximum intensity of C1s in the obtained spectrum may be corrected to 284.8 eV. The average of the peak intensities between 158 eV and 157 eV may be used as the background. The ratio of the maximum peak intensity between 162 eV and 164 eV to the maximum peak intensity between 160.5 eV and 162.5 eV may be calculated. The maximum peak intensity between 162 eV and 164 eV may be, for example, the peak intensity value at 163 eV. The maximum peak intensity between 160.5 eV and 162.5 eV may be, for example, the peak intensity value at 161.5 eV.

[0034] In the electrode active material layer of this disclosure, the peak intensity of the spectrum obtained by FT-IR measurement may satisfy the following relation (2): 0 <I(3200) / I(3400)≦0.7 … (2) During the ceremony, I(3200): 3200±50cm in FT-IR measurements -1 Peak intensity, I(3400): 3400±50cm in FT-IR measurements -1 Peak intensity.

[0035] In the above relation (2), I(3200) is the reference peak, and I(3400) is the Si-OH peak. Si-OH is produced from oxidized silicon. Therefore, I(3200) / I(3400) indicates the degree of oxidation of the silicon-based electrode active material.

[0036] When the above relationship (2) is satisfied, the battery's capacity retention rate can be effectively improved. The reason for this is that, although we do not intend to be bound by any theory, the moderate oxidation of the silicon-based electrode active material suppresses the reaction of the sulfide solid electrolyte catalyzed by silicon, thereby improving the capacity retention rate.

[0037] I(3200) / I(3400) may be 0.10 or greater, 0.15 or greater, 0.20 or greater, or 0.25 or greater, and may also be 0.65 or less, or 0.60 or less.

[0038] <ft-ir> Shell Fisher Company Nicolet TM iS TM Using a 50 FT-IR, FT-IR (Fourier Transform Infrared Spectroscopy) measurements can be performed using the Attenuated Total Reflection (ATR) method. Background processing may be applied to the obtained samples.

[0039] In the electrode active material layer of this disclosure, the peak intensity of the spectrum obtained by XPS measurement and the peak intensity of the spectrum obtained by FT-IR measurement may satisfy the following relationship (3): 0.70≦(I(163.0) / I(161.5)) / (I(3200) / I(3400))≦2.0… (3).

[0040] When the above relationship (3) is satisfied, the battery capacity retention rate can be effectively improved.

[0041] (I(163.0) / I(161.5)) / (I(3200) / I(3400)) may be 0.75 or greater, 0, 80 or greater, or 0.90 or greater, and may be 1.90 or less, 1.85 or less, 1.80 or less, or 1.75 or less.

[0042] The electrode active material layer may optionally further contain conductive additives, binders, etc.

[0043] (Conductive additive) The conductive additive is not particularly limited and may be, for example, VGCF (Vapor Grown Carbon Fiber), acetylene black (AB), Ketjenblack (KB), carbon nanotubes (CNT), carbon nanofibers (CNF), or a combination thereof.

[0044] (binder) The binder is not particularly limited and may be, for example, polyvinylidene fluoride (PVDF), butadiene rubber (BR), styrene-butadiene rubber (SBR), or a combination thereof.

[0045] <<Method for manufacturing electrode active material layer>> The electrode active material layer of this disclosure can be manufactured by a method comprising the following steps (a) to (d): (a) Prepare an electrode mixture slurry containing an electrode active material, a sulfide solid electrolyte, and a dispersion medium. (b) Apply the electrode mixture slurry to the substrate. (c) Drying and removing the dispersion medium to form an electrode active material layer, and (d) Densifying the electrode active material layer.

[0046] <Electrode mixture slurry preparation process> The electrode active material layer of this disclosure can be manufactured by a method comprising (a) preparing an electrode mixture slurry comprising an electrode active material, a sulfide solid electrolyte, and a dispersion medium.

[0047] In this disclosure, “compound mixture” means a composition that can constitute an active material layer, either in itself or by further containing other components. In this disclosure, “compound mixture slurry” means a slurry that includes a dispersion medium in addition to the “compound mixture,” and thereby can be applied and dried to form an active material layer.

[0048] The slurry can be prepared by conventional methods, that is, by mixing each component.

[0049] <Electrode mixture slurry application process> The electrode active material layer of this disclosure can be manufactured by a method comprising (b) applying an electrode mixture slurry to a substrate.

[0050] The method for applying the electrode mixture slurry to the substrate is not particularly limited, and one example is the blade method using an applicator.

[0051] The base material is not particularly limited and may be, for example, an electrode current collector layer. That is, for example, if the electrode mixture is a negative electrode mixture, the base material may be a negative electrode current collector layer, and if the electrode mixture is a positive electrode mixture, the base material may be a positive electrode current collector layer. The base material may also be a release sheet or the like.

[0052] <Electrode active material layer formation process> The electrode active material layer of this disclosure can be manufactured by a method comprising (c) drying and removing the dispersion medium to form the electrode active material layer.

[0053] The method for drying out the dispersion medium is not particularly limited, and one example is to leave it standing on a hot plate at a predetermined temperature for a predetermined time. The drying temperature and drying time are not particularly limited and can be set appropriately based on the amount of dispersion medium used, its boiling point, etc.

[0054] <Densification process> The electrode active material layer of this disclosure can be manufactured by a method that includes (d) densifying the electrode active material layer.

[0055] The method for densifying the electrode active material layer is not particularly limited, and one example is pressing the electrode active material layer. The pressing pressure, pressing temperature, etc., are not particularly limited and can be set appropriately considering the desired electrode density, etc.

[0056] <First Environment and Second Environment> One, two, or three of steps (a) to (d) may be carried out in a first environment with an oxygen concentration of 1 volume% or more, and the other steps (a) to (d) may be carried out in a second environment with an oxygen concentration of less than 1 volume%. With such a method, the oxidation state of the surface of the solid electrolyte can be easily adjusted, and therefore the electrode active material of this disclosure can be easily manufactured.

[0057] The oxygen concentration in the first environment may be 3% by volume or more, 5% by volume or more, 10% by volume or more, 15% by volume or more, or 20% by volume or more, and may be 40% by volume or less, 30% by volume or less, or 25% by volume or less. The oxygen concentration in the first environment may also be similar to that in the atmosphere, i.e., about 21% by volume.

[0058] The oxygen concentration in the second environment is 1 × 10⁻⁶ -1 Volume % (1000 volume ppm) or less, 1 × 10 -2 Less than or equal to volume percent (less than or equal to 100 volume ppm), 1 × 10⁻¹⁰ -3 Volume percent or less (10 volume ppm or less), or 5 × 10 -4 It may be less than or equal to a volume percent (5 volume ppm).

[0059] The dew point of the first environment may be -65°C or higher, and / or the dew point of the second environment may be below -65°C.

[0060] The dew point of the first environment may be -60°C or higher, -55°C or higher, or -50°C or higher, and may be -20°C or lower, -25°C or lower, -30°C or lower, -35°C or lower, -40°C or lower, -45°C or lower, or -50°C or lower, and may also be -50°C.

[0061] The dew point of the second environment may be -100°C or higher, -95°C or higher, -90°C or higher, -85°C or higher, or -80°C or higher, and may be -70°C or lower, -75°C or lower, or -80°C or lower, or -80°C.

[0062] The first environment may be a dry air atmosphere, and the second environment may be an inert gas atmosphere.

[0063] For the purposes of this disclosure, dry air means air with low moisture content and therefore a lower dew point than atmospheric air. A dry air atmosphere may be the atmosphere inside a dry room filled with dry air.

[0064] The inert gas is not particularly limited and may be nitrogen gas, argon gas, etc. The inert gas atmosphere may be the atmosphere inside a glove box filled with the inert gas.

[0065] The number of processes performed in the first environment may be one, two, or three. In particular, one of processes (a) to (d) may be performed in the first environment.

[0066] Process (a) and / or process (b) may be carried out in the first environment, and in particular, process (b) may be carried out in the first environment.

[0067] The total time spent performing operations in the first environment is not particularly limited and may be, for example, 1 minute or more, 10 minutes or more, 30 minutes or more, or 1 hour or more, or 10 hours or less, 5 hours or less, 3 hours or less, or 1 hour or less.

[0068] Furthermore, the "total time spent performing operations in the first environment" includes not only the time spent performing each of the processes (a) to (d) in the first environment, but also the time spent before and after each process in the first environment. Therefore, if the electrode mixture slurry is left to stand in the first environment after preparation but before application, that standing time is included in the "total time spent performing operations in the first environment."

[0069] <<Battery>> As illustrated in Figure 1, the battery 100 of the present disclosure has an electrode active material layer. The battery of the present disclosure may have a negative electrode current collector layer 110, a negative electrode active material layer 120, an electrolyte layer 130, a positive electrode active material layer 140, and a positive electrode current collector layer 150 in this order.

[0070] The battery of this disclosure may be a liquid-type battery containing an electrolyte as an electrolyte layer, or it may be a solid-state battery having a solid electrolyte layer as an electrolyte layer. The battery of this disclosure may be a solid-state battery in particular. In this disclosure, "solid-state battery" means a battery that uses at least a solid electrolyte as an electrolyte, and therefore a solid-state battery may use a combination of a solid electrolyte and a liquid electrolyte as an electrolyte. Furthermore, a solid-state battery may be an all-solid-state battery, that is, a battery that uses only a solid electrolyte as an electrolyte.

[0071] The battery may be a primary battery or a secondary battery, and may be a lithium-ion secondary battery in particular.

[0072] The following describes the various elements that may constitute the battery of this disclosure. Specifically, the following examples illustrate the case where the battery of this disclosure is an all-solid-state lithium-ion secondary battery, that is, where the electrolyte is a solid electrolyte, and therefore the electrolyte layer is a solid electrolyte layer, and the electrode active material layer of this disclosure is a negative electrode active material layer.

[0073] <Negative electrode current collector layer> The material constituting the negative electrode current collector layer is not particularly limited and may be, for example, copper or a copper alloy, or copper plated or deposited with nickel, chromium, carbon, etc.

[0074] The shape of the negative electrode current collector layer is not particularly limited and may be, for example, foil-shaped, plate-shaped, mesh-shaped, etc., and may be particularly foil-shaped.

[0075] <Negative electrode active material layer> In the exemplary embodiments described above, the negative electrode active material layer is the electrode active material layer of the present disclosure. For details of the electrode active material layer of the present disclosure, refer to the above description relating to the electrode active material layer of the present disclosure.

[0076] Furthermore, if the negative electrode active material layer contains a solid electrolyte, the mass ratio of the electrode active material to the solid electrolyte in the negative electrode active material layer (mass of electrode active material:mass of solid electrolyte) may be 85:15 to 30:70, or 80:20 to 40:60.

[0077] The thickness of the negative electrode active material layer may be, for example, 0.1 μm to 1000 μm, 1 μm to 100 μm, or 30 μm to 100 μm.

[0078] <Solid electrolyte layer> The solid electrolyte layer comprises at least a solid electrolyte and may optionally contain a binder or the like. For details regarding the solid electrolyte and binder, please refer to the above description concerning the electrode active material layer in this disclosure.

[0079] The thickness of the solid electrolyte layer may be, for example, 0.1 to 300 μm, or 0.1 to 100 μm.

[0080] <Cathode active material layer> The positive electrode active material layer contains a positive electrode active material and may optionally contain an electrolyte, a conductive additive, a binder, etc. For details on each of these components, please refer to the above description of the electrode active material layer in this disclosure.

[0081] Furthermore, if the positive electrode active material layer contains a solid electrolyte, the mass ratio of the positive electrode active material to the solid electrolyte in the positive electrode active material layer (mass of positive electrode active material:mass of solid electrolyte) may be 85:15 to 30:70, or 80:20 to 50:50.

[0082] The thickness of the positive electrode active material layer may be, for example, 0.1 μm to 1000 μm, 1 μm to 100 μm, or 30 μm to 100 μm.

[0083] <Positive electrode current collector layer> The material constituting the positive electrode current collector layer is not particularly limited and may be, for example, SUS, nickel, chromium, gold, platinum, aluminum, iron, titanium, zinc, etc., or these metals may be plated or deposited with nickel, chromium, carbon, etc.

[0084] The shape of the positive electrode current collector layer is not particularly limited and may be, for example, foil-shaped, plate-shaped, mesh-shaped, etc., and may be particularly foil-shaped.

[0085] <Other configurations> The battery may have all of the above components housed inside an outer casing. Any known battery casing can be used. Furthermore, multiple batteries may be electrically connected and stacked as desired to form a battery pack. In this case, the battery pack may be housed inside a known battery case. The battery may also have other obvious components such as necessary terminals. Examples of battery shapes include coin-type, laminated (pouch) type, cylindrical type, and prismatic type.

[0086] The battery can be restrained from both sides of the stacking direction of each layer by restraining members such as end plates. Examples of restraining methods include, but are not limited to, methods that utilize the restraining torque of bolts. [Examples]

[0087] <<Example 1>> <Synthesis of electrode active materials> Metallic lithium (Li) and silicon (Si) powder were weighed in a molar ratio of 4:1 and reacted in a mortar and pestle under an argon (Ar) atmosphere at room temperature for 0.5 hours. This yielded lithium silicon (Li4Si). The obtained Li4Si was reacted with ethanol under an Ar atmosphere. The reaction product was filtered, and the filtered solid was dried at 120°C for more than 3 hours to obtain powdered porous Si as a silicon electrode active material.

[0088] <Formation of the negative electrode active material layer> Unless otherwise specified, the formation of the negative electrode active material layer was carried out in an environment with an oxygen concentration of 5 ppm or less and a dew point of -80°C or less. Note that the densification process, although described in the section on battery fabrication for convenience, is included in the formation of the negative electrode active material layer.

[0089] (Negative electrode slurry preparation process) A 5 wt% butyl butyrate solution of butyl butyrate and a butadiene rubber (BR)-based binder, vapor-grown carbon fiber (VGCF) as a conductive additive, synthesized silicon electrode active material as a negative electrode active material, and Li2S-P2S5-based glass ceramic as a sulfide solid electrolyte were added to a polypropylene container and stirred for 30 seconds using an ultrasonic disperser (SMT Co., Ltd., UH-50). Next, the container was shaken for 30 minutes using a shaker (Shibata Scientific Co., Ltd., TTM-1) to obtain a negative electrode mixture slurry. After that, it was left to stand for 1 hour in an environment with an oxygen concentration of approximately 21 volume% and a dew point of -50°C.

[0090] (Negative electrode slurry application process) The obtained negative electrode mixture slurry was applied to a copper (Cu) foil (manufactured by UACJ) to serve as the negative electrode current collector layer using an applicator and the blade method.

[0091] (drying process) A Cu foil coated with a negative electrode composite slurry was dried on a hot plate heated to 100°C for 30 minutes to form the electrode active material layer of this disclosure, which serves as the negative electrode active material layer, on the negative electrode current collector layer.

[0092] <Formation of the solid electrolyte layer> A 5 wt% heptane solution of heptane and a butadiene rubber (BR) binder, along with a Li2S-P2S5 glass ceramic as a sulfide solid electrolyte, were added to a polypropylene container and stirred for 30 seconds using an ultrasonic disperser (SMT Co., Ltd., UH-50). Next, the container was shaken for 30 minutes using a shaker (Shibata Scientific Co., Ltd., TTM-1) to obtain a solid electrolyte slurry. The obtained solid electrolyte slurry was applied to an aluminum (Al) foil, which served as a release sheet, using an applicator and the blade method. The Al foil coated with the solid electrolyte slurry was dried on a hot plate heated to 100°C for 30 minutes to form a solid electrolyte layer. Three solid electrolyte layers were prepared.

[0093] <Formation of the positive electrode active material layer> A polypropylene container contains a 5 wt% butyl butyrate solution of butyl butyrate and a polyvinylidene fluoride (PVDF) binder, and LiNi with an average particle size of 6 μm as the positive electrode active material. 1 / 3 Co 1 / 3 Mn 1 / 3 O2, Li2S-P2S5 glass ceramic as a sulfide solid electrolyte, and VGCF as a conductive additive were added to a container and stirred for 30 seconds using an ultrasonic disperser (SMT Co., Ltd., UH-50). Next, the container was shaken for 3 minutes using a shaker (Shibata Scientific Co., Ltd., TTM-1), stirred for 30 seconds using the ultrasonic disperser, and then shaken again for 3 minutes using the shaker to obtain a positive electrode mixture slurry. The obtained positive electrode mixture slurry was applied to an Al foil (Showa Denko Co., Ltd.) to serve as the positive electrode current collector layer using an applicator and the blade method. The Al foil coated with the positive electrode mixture slurry was dried on a hot plate heated to 100°C for 30 minutes to form a positive electrode active material layer on the positive electrode current collector layer.

[0094] <Battery manufacturing> The negative electrode current collector layer, the negative electrode active material layer, and the first solid electrolyte layer were laminated in this order. The solid electrolyte layer was laminated so that the side without the Al foil faced the negative electrode active material layer.

[0095] (densification process) This laminate was set in a roll press and pressed at a press pressure of 60 kN / cm and a press temperature of 25°C to obtain a densified negative electrode laminate.

[0096] The positive electrode current collector layer, the positive electrode active material layer, and the second solid electrolyte layer were laminated in this order. The solid electrolyte layer was laminated so that the side without the Al foil faced the positive electrode active material layer. This laminate was then placed in a roll press and pressed at a press pressure of 100 kN / cm and a press temperature of 165°C to obtain the positive electrode laminate.

[0097] The area of ​​the negative electrode stack was larger than the area of ​​the positive electrode stack.

[0098] The aluminum foil, acting as a release sheet, was peeled off the surface of the first solid electrolyte layer. A third solid electrolyte layer was then laminated onto the first solid electrolyte layer of the exposed anode laminate. This laminate was placed in a flat-axis press and pre-pressed at 100 MPa and 25°C for 10 seconds. The aluminum foil was peeled off the third solid electrolyte layer, obtaining an anode laminate with an additional third solid electrolyte layer.

[0099] The aluminum foil, acting as a release sheet, was peeled off the surface of the second solid electrolyte layer. The second solid electrolyte layer was then laminated onto the third solid electrolyte layer. This laminate was placed in a flat-axis press and pressed for 1 minute at a press pressure of 200 MPa and a press temperature of 120°C. This resulted in the creation of an all-solid-state battery.

[0100] <Rating> (XPS measurement) XPS measurements were performed using ULVAC-FI's VersaprobeII. In the obtained spectra, the maximum intensity of C1s was corrected to 284.8 eV. The average of the peak intensities between 158 eV and 157 eV was used as the background. The ratio of the maximum peak intensity between 162 eV and 164 eV to the maximum peak intensity between 160.5 eV and 162.5 eV (I(163.0) / I(161.5)) was calculated. The maximum peak intensity between 162 eV and 164 eV was the peak intensity value at 163 eV. The maximum peak intensity between 160.5 eV and 162.5 eV was the peak intensity value at 161.5 eV.

[0101] (FT-IR measurement) Shell Fisher Company Nicolet TM iS TM FT-IR measurements were performed using the Attenuated Total Reflection (ATR) method with a 50 FT-IR sensor. The obtained samples were then subjected to background processing. (3200±50 cm) -1 The peak intensity is 3400±50cm. -1 The ratio of (I(3200) / I(3400)) to the peak intensity was calculated.

[0102] (Calculation of capacity retention rate) Using a restraining jig, the fabricated all-solid-state battery was restrained at a predetermined restraining pressure and charged with constant current and constant voltage to 4.55V at a 10-hour rate (1 / 10C), and then discharged to 3.0V at a 1-hour rate (1C). Furthermore, it was charged with constant current and low voltage to 4.35V at a 3-hour rate (1 / 3C), and then discharged with constant current and constant voltage to 3.00V at a 3-hour rate (1 / 3C) to define the initial capacity. Subsequently, the same charge-discharge test was repeated five times, and the capacity retention rate from the initial capacity was calculated.

[0103] <<Example 2>> A solid-state battery was obtained and evaluated in the same manner as in Example 1, except that the process, which is carried out in an environment with an oxygen concentration of approximately 21 volume% and a dew point of -50°C, was changed to an electrode composite slurry coating process, i.e., the electrode composite slurry was coated in this environment.

[0104] <<Example 3>> An all-solid-state battery was obtained and evaluated in the same manner as in Example 1, except that the process, which is carried out in an environment with an oxygen concentration of approximately 21 volume% and a dew point of -50°C, was changed to an electrode mixture slurry coating process and a drying process; that is, the electrode mixture slurry was coated in this environment and the dispersion medium in the electrode mixture slurry was dried and removed.

[0105] <<Comparative Example 1>> All solid-state batteries were obtained and evaluated in the same manner as in Example 1, except that each process was not carried out in an environment with an oxygen concentration of approximately 21 volume% and a dew point of -50°C, and the electrode composite slurry coating process was carried out in an environment with an oxygen concentration of 500 ppm and a dew point of -80°C.

[0106] <<Comparative Example 2>> An all-solid-state battery was obtained and evaluated in the same manner as in Example 1, except that the electrode mixture slurry preparation process, electrode mixture slurry coating process, drying process, and densification process were carried out in an environment with an oxygen concentration of approximately 21 volume% and a dew point of -50°C.

[0107] Table 1 shows the evaluation results for each example, namely I(163.0) / I(161.5), I(3200) / I(3400), and (I(163.0) / I(161.5)) / (I(3200) / I(3400)), as well as the volume retention rate. Note that the volume retention rate is shown as a relative value with the value of Comparative Example 2 set to 100.

[0108] [Table 1]

[0109] As shown in Table 1, batteries having an electrode active material layer where I(163.0) / I(161.5) is within a predetermined range, i.e., where the peak intensity of the spectrum obtained by XPS measurement satisfies relation (1), showed a high capacity retention rate. [Explanation of symbols]

[0110] 100 batteries 110 Negative electrode current collector layer 120 Negative electrode active material layer 130 Electrolyte layer 140 Cathode active material layer 150 Positive electrode current collector layer

Claims

1. It comprises an electrode active material and a sulfide solid electrolyte, and The peak intensity of the spectrum obtained by XPS measurement satisfies the following relationship (1): 0.40≦I(163.0) / I(161.5)≦0.60… (1) During the ceremony, I(163.0): Maximum peak intensity of 163.0 ± 1.0 eV, I(161.5): Maximum peak intensity of 161.5 ± 1.0 eV, Electrode active material layer.

2. The electrode active material layer according to claim 1, wherein the electrode active material is a silicon-based electrode active material.

3. The peak intensity of the spectrum obtained by FT-IR measurement satisfies the following relationship (2): 0<I(3200) / I(3400)≦0.7… (2) During the ceremony, I (3200): 3200±50cm －１ Peak intensity, I (3400): 3400±50cm －１ Peak intensity, The electrode active material layer according to claim 2.

4. The sulfide solid electrolyte is Li ２ S-P ２ S ５ The electrode active material layer according to claim 1, wherein the material is a glass ceramic.

5. A battery having an electrode active material layer according to any one of claims 1 to 4.

6. The battery according to claim 5, wherein the electrode active material layer is a negative electrode active material layer.

7. The battery according to claim 5, which is a solid-state battery.

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