Solid-state battery and method for manufacturing the same

Abstract

To realize a solid state battery having an electrode layer which can obtain an excellent battery performance.SOLUTION: A solid state battery 1 includes: a positive electrode layer 10 containing an oxide solid electrolyte and a positive electrode active material; a negative electrode layer 20 containing the oxide solid electrolyte and a negative electrode active material; and an electrolyte layer 30 that is provided between the positive electrode layer 10 and the negative electrode layer 20, and contains the oxide solid electrolyte. In the negative electrode layer 20, a rectangular crystal Nb2O5 is contained as a negative electrode active material in addition to an anatase type TiO2. The rectangular crystal Nb2O5 also functions as a sintering aid. By using such a negative electrode active material, a deterioration of a sintering density of the negative electrode layer 20 at the time of sintering under an oxidative atmosphere is suppressed, and an increase of a resistance due to the deterioration of the sintering density, and the reduction of an energy density of a solid state battery 1 is suppressed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a solid-state battery and a method for manufacturing a solid-state battery. [Background technology]

[0002] A known solid-state battery has a cathode layer made of an electrode material containing a solid electrolyte and an active material on one side of an electrolyte layer made of a solid electrolyte, and a anode layer made of an electrode material containing a solid electrolyte and an active material on the other side. For example, a technique for using an electrode material containing an active material such as spherical particles of niobium pentoxide (NbO) or titanium oxide (TiO) having an average aspect ratio of 1 or more and less than 1.15 as the electrode material, and a technique for sintering a mixture of such an active material and a solid electrolyte at a temperature equal to or higher than the softening point of the solid electrolyte are known.

[0003] Furthermore, with regard to a method for producing a ceramic molded body for sintering, a technique is known in which a raw material powder containing a ceramic powder and a thermoplastic resin having a glass transition temperature higher than room temperature is isostatically pressed at a temperature lower than the glass transition temperature of the thermoplastic resin, and then the raw material powder is heated to a temperature equal to or higher than the glass transition temperature of the thermoplastic resin and is isostatically pressed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-102911 [Patent Document 2] Japanese Patent Application Publication No. 2019-199078 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in the manufacture of a solid-state battery using an oxide solid electrolyte as the solid electrolyte, plastic positive and negative electrode layers (also referred to as "electrode layers") and an electrolyte layer are formed using an organic binder or the like, and these are stacked in a predetermined order and cut, and then fired in an oxidizing atmosphere to burn off organic components such as the binder (also referred to as "desolvation") and to bond particles of the oxide solid electrolyte together (also referred to as "sintering").

[0006] In this case, it is believed that the electrode layer is sintered at a temperature equal to or higher than the glass softening point of the oxide solid electrolyte and that the grain growth of the active material at that time fills in the areas where the organic components such as the binder have been burned off, making the layer denser. However, it is not necessarily easy to control the glass softening point of the oxide solid electrolyte and the grain growth of the active material. As a result, it may not be possible to obtain an electrode layer that can achieve high battery performance, or a solid-state battery equipped with such an electrode layer.

[0007] Furthermore, when a dense ceramic compact for sintering obtained by pressure molding is used to form an electrode layer, if the organic components are burned away by firing in an oxidizing atmosphere, the burned-away portions remain as voids in the electrode layer, which can become a resistive layer or cause defects. As a result, it may be impossible to obtain an electrode layer that can achieve high battery performance, or a solid-state battery equipped with such an electrode layer.

[0008] In one aspect, an object of the present invention is to provide a solid-state battery having an electrode layer that can provide excellent battery performance. [Means for solving the problem]

[0009] In one embodiment, the battery includes a cathode layer including a first oxide solid electrolyte and a cathode active material, an anode layer including a second oxide solid electrolyte and a cathode active material, and an electrolyte layer provided between the cathode layer and the anode layer and including a third oxide solid electrolyte, wherein the anode active material includes anatase TiO2 and orthorhombic Nb2O5. the anatase type TiO contained in the negative electrode active material 2 The weight of the orthorhombic Nb 2 O 5 The weight ratio of A solid-state battery is provided.

[0010] In one embodiment, a method for producing the above solid-state battery is provided. [Effects of the Invention]

[0011] In one aspect, it becomes possible to realize a solid-state battery having an electrode layer that can provide excellent battery performance. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating an example of a solid-state battery. [Figure 2] FIG. 1 is a diagram illustrating an example of a configuration of a solid-state battery. [Figure 3] FIG. 1 is a diagram (part 1) for explaining a first example of forming a solid-state battery body. [Figure 4] FIG. 2 is a diagram (part 2) for explaining a first example of forming a solid-state battery body. [Figure 5] FIG. 10 is a diagram (part 1) for explaining a second example of forming a solid state battery body. [Figure 6] FIG. 10 is a diagram (part 2) for explaining a second example of forming a solid state battery body. [Figure 7] FIG. 10 is a diagram (part 1) for explaining a third example of forming a solid state battery body. [Figure 8] FIG. 10 is a diagram (part 2) for explaining a third example of forming a solid state battery body. [Figure 9] 1A and 1B are diagrams illustrating firing of the basic structure of a solid-state battery body. [Figure 10] 1 is an example of an SEM image of a cross section of a negative electrode layer after firing of a solid-state battery containing anatase TiO 2 and orthorhombic Nb 2 O 5 (weight ratio 1:1) as negative electrode active materials. [Figure 11] 1 is an example of an SEM image of a cross section of a negative electrode layer after firing of a solid-state battery containing only anatase-type TiO2 as the negative electrode active material. [Figure 12] 1 is an example of a charge / discharge curve diagram of a solid battery containing anatase TiO 2 and orthorhombic Nb 2 O 5 (weight ratio 1:1) as negative electrode active materials. [Figure 13]1 is an example of a charge / discharge curve diagram of a solid-state battery containing only anatase-type TiO2 as the negative electrode active material. [Figure 14] FIG. 10 is a graph showing the change in discharge capacity versus charge / discharge rate for a solid battery containing anatase TiO 2 and orthorhombic Nb 2 O 5 (weight ratio 1:1) as negative electrode active materials, and a solid battery containing only anatase TiO 2 as negative electrode active material. [Figure 15] FIG. 10 is a diagram illustrating another configuration example of a solid-state battery. [Figure 16] FIG. 10 is a diagram showing yet another configuration example of a solid-state battery. DETAILED DESCRIPTION OF THE INVENTION

[0013] Lithium-ion secondary batteries have significantly contributed to the miniaturization and weight reduction of devices, and their applications are expanding, including electric vehicles, stationary energy storage facilities, personal digital assistants, IoT (Internet of Things) devices, and wearable devices. Accordingly, the required specifications are becoming more diverse, and expectations for high energy density and safety are rising. To meet these demands, solid-state batteries are being developed as a new type of battery. One type of solid-state battery is known to use a solid electrolyte material as the electrolyte. Because such solid-state batteries do not use flammable organic electrolyte solutions, they can reduce the risks of leakage, combustion, explosion, and toxic gas generation, thereby improving safety. They are easy to handle in the atmosphere and can maintain their performance even at low and high temperatures. The use of solid electrolyte materials allows for the use of cathode active materials that operate at higher voltages, which is expected to further improve the performance of solid-state batteries, such as by increasing energy density.

[0014] [Solid battery] Fig. 1 is a diagram illustrating an example of a solid-state battery, which schematically shows a cross-sectional view of a main part of an example of a solid-state battery.

[0015] The solid-state battery 1 shown in FIG. 1 includes a positive electrode layer 10, a negative electrode layer 20, and an electrolyte layer 30 provided therebetween. The electrolyte layer 30 contains a solid electrolyte material. An oxide solid electrolyte is used as the solid electrolyte material of the electrolyte layer 30. For the electrolyte layer 30, for example, LAGP, which is one type of oxide solid electrolyte of the NASICON (Na super ionic conductor) type (also referred to as the "NASICON type"), is used. LAGP is an oxide solid electrolyte represented by the general formula Li 1+x Al x Ge 2-x (PO4)3 (0 < x ≤ 1), and is also referred to as aluminum-substituted lithium germanium phosphate, etc. In this example, as the LAGP of the electrolyte layer 30, Li 1.5 Al 0.5 Ge 1.5 (PO4)3 with a composition ratio of x = 0.5 is used.

[0016] The positive electrode layer 10 provided on one surface 30a side of the electrolyte layer 30 contains a solid electrolyte material and a positive electrode active material. An oxide solid electrolyte is used as the solid electrolyte material of the positive electrode layer 10. For the oxide solid electrolyte of the positive electrode layer 10, for example, the same type of material as the oxide solid electrolyte used for the electrolyte layer 30 is used. That is, in this example, LAGP is used as the oxide solid electrolyte of the positive electrode layer 10. For the positive electrode active material of the positive electrode layer 10, for example, lithium cobalt pyrophosphate (Li2CoP2O7, hereinafter referred to as "LCPO") is used. In addition to the solid electrolyte material and the positive electrode active material, the positive electrode layer 10 may contain a conductive aid. For the conductive aid of the positive electrode layer 10, for example, carbon materials such as carbon fiber, carbon black, graphite, graphene, and carbon nanotubes are used.

[0017] The anode layer 20 provided on the other surface 30b of the electrolyte layer 30 includes a solid electrolyte material and an anode active material. The solid electrolyte material of the anode layer 20 is an oxide solid electrolyte. The oxide solid electrolyte of the anode layer 20 is, for example, the same material as the oxide solid electrolyte used in the electrolyte layer 30. That is, in this example, LAGP is used as the oxide solid electrolyte of the anode layer 20. The anode active material of the anode layer 20 includes titanium (Ti) oxide and niobium (Nb) oxide. Anatase-type TiO2 is used as the Ti oxide of the anode active material, and orthorhombic Nb2O5 is used as the Nb oxide of the anode active material. Anatase-type TiO2 and orthorhombic Nb2O5 coexist in the anode layer 20 in the form of their respective crystal structures. In addition to the solid electrolyte material and the anode active material, the anode layer 20 may also include a conductive additive. The conductive additive for the negative electrode layer 20 may be, for example, a carbon material such as carbon fiber, carbon black, graphite, graphene, or carbon nanotube.

[0018] In the solid-state battery 1 having the electrolyte layer 30, the positive electrode layer 10, and the negative electrode layer 20 as described above, lithium ions are conducted from the positive electrode layer 10 to the negative electrode layer 20 via the electrolyte layer 30 and are taken up during charging, and lithium ions are conducted from the negative electrode layer 20 to the positive electrode layer 10 via the electrolyte layer 30 and are taken up during discharging. In the solid-state battery 1, charge and discharge operations are realized by such lithium ion conduction.

[0019] The solid state battery 1 having the above configuration is manufactured, for example, by the following method. As an example, green sheets for the electrolyte layer, green sheets for the positive electrode layer, and green sheets for the negative electrode layer are prepared by a doctor blade method or the like. The green sheets for the electrolyte layer are formed using a material including a LAGP oxide solid electrolyte and an organic binder. The green sheets for the positive electrode layer are formed using a material including, for example, a LAGP oxide solid electrolyte, a LCPO cathode active material, a carbon-based conductive additive, and an organic binder. The green sheets for the negative electrode layer are formed using a material including, for example, a LAGP oxide solid electrolyte, anatase TiO2 and orthorhombic Nb2O5 anode active materials, a carbon-based conductive additive, and an organic binder. The green sheets for the electrolyte layer, the positive electrode layer, and the negative electrode layer are stacked so that the electrolyte layer green sheets are interposed between the positive electrode layer green sheets and the negative electrode layer green sheets, and then fired. The firing is performed in an oxidizing atmosphere containing oxidizing gases such as air and oxygen. This firing burns off organic components, such as organic binders, contained in the electrolyte layer green sheets, the positive electrode layer green sheets, and the negative electrode layer green sheets, thereby removing the solvent. Further firing in the oxidizing atmosphere (also referred to as "main firing") sinters the materials remaining in the electrolyte layer green sheets, the positive electrode layer green sheets, and the negative electrode layer green sheets. This produces a solid-state battery 1 having a structure in which the electrolyte layer 30 is sandwiched between the positive electrode layer 10 and the negative electrode layer 20.

[0020] In another example, an electrolyte layer green sheet or sintered body is prepared, followed by a positive electrode layer paste (or slurry) and a negative electrode layer paste (or slurry). The electrolyte layer green sheet is formed using a material containing LAGP, an oxide solid electrolyte, and an organic binder. The electrolyte layer sintered body is formed by compacting and sintering the LAGP powder. The positive electrode layer paste is formed using, for example, a material containing LAGP, an oxide solid electrolyte, LCPO, a positive electrode active material, a carbon-based conductive additive, and an organic binder. The negative electrode layer paste is formed using, for example, a material containing LAGP, an oxide solid electrolyte, anatase TiO and orthorhombic NbO, a negative electrode active material, a carbon-based conductive additive, and an organic binder. The positive electrode layer paste and the negative electrode layer paste are applied by screen printing or the like so that the electrolyte layer green sheet or sintered body is sandwiched between them. Then, firing is performed in an oxidizing atmosphere to burn off organic components such as organic binders and remove the solvent. Further, main firing in an oxidizing atmosphere sinters the materials remaining in the positive electrode layer paste and the negative electrode layer paste. This produces a solid-state battery 1 having a structure in which the electrolyte layer 30 is interposed between the positive electrode layer 10 and the negative electrode layer 20.

[0021] The method for manufacturing the solid state battery 1 will be described in detail later. As described above, in the solid-state battery 1, anatase TiO2 and orthorhombic Nb2O5 are contained as the negative electrode active material of the negative electrode layer 20. Anatase TiO2 and orthorhombic Nb2O5 coexist in the negative electrode layer 20 in the form of their respective crystal structures.

[0022] Here, when only anatase TiO2 is contained as the negative electrode active material of the negative electrode layer 20 of the solid-state battery 1, out of anatase TiO2 and orthorhombic Nb2O5, aggregation of TiO2 may occur easily during desolvation in an oxidizing atmosphere or firing for main firing as described above. When aggregation of TiO2 occurs, the sinterability of the negative electrode layer 20 decreases, the sintered density decreases, and there is a risk of increasing the resistance of the negative electrode layer 20 obtained as a sintered body by firing in an oxidizing atmosphere and decreasing the energy density of the solid-state battery 1 including the negative electrode layer 20.

[0023] In contrast, when orthorhombic NbO is included in addition to anatase TiO as the negative electrode active material of the negative electrode layer 20 of the solid-state battery 1, the orthorhombic NbO functions not only as the negative electrode active material but also as a sintering aid. This prevents the aggregation of TiO during desolvation and firing in an oxidizing atmosphere as described above, and the resulting decrease in the sinterability and sintered density of the negative electrode layer 20. As a result, an increase in the resistance of the negative electrode layer 20 obtained as a sintered body by firing in an oxidizing atmosphere and a decrease in the energy density of the solid-state battery 1 including the negative electrode layer 20 are effectively prevented.

[0024] By using both anatase TiO2 and orthorhombic Nb2O5 as the negative electrode active materials, a solid-state battery 1 including a negative electrode layer 20 that can achieve excellent battery performance is realized. [Solid-state battery manufacturing] Next, a method for manufacturing a solid-state battery having the above-described configuration will be described. Here, the manufacturing method will be described using a chip-type solid-state battery as shown in the following Figure 2 as an example.

[0025] FIG. 2 is a diagram showing an example of the configuration of a solid-state battery. FIG. 2(A) is a schematic perspective view of the exterior of an example of a solid-state battery. FIG. 2(B) is a schematic cross-sectional view of a main part of an example of a solid-state battery. FIG. 2(B) is an example of a cross section taken along plane P1 of FIG. 2(A).

[0026] The solid state battery 1A shown in FIGS. 2(A) and 2(B) is an example of a chip-type battery, and includes a solid state battery body 1Aa and a current collector 40 and a current collector 50 provided at both ends thereof, respectively.

[0027] As shown in FIG. 2(B), the solid-state battery body 1Aa has a structure in which an electrolyte layer 30, a positive electrode layer 10, and a negative electrode layer 20 are stacked. One electrolyte layer 30 is interposed between a pair of the positive electrode layer 10 and the negative electrode layer 20, and one electrolyte layer 30 is provided above the uppermost positive electrode layer 10 and below the lowermost negative electrode layer 20. The positive electrode layer 10 is connected to a current collector 40 provided at one end of the solid-state battery body 1Aa, and the negative electrode layer 20 is connected to a current collector 50 provided at the other end of the solid-state battery body 1Aa. The side of the positive electrode layer 10 is surrounded by, for example, an electrolyte layer 30 provided in the same layer as the positive electrode layer 10, except for the connection portion with the current collector 40. The side of the negative electrode layer 20 is surrounded by, for example, an electrolyte layer 30 provided in the same layer as the negative electrode layer 20, except for the connection portion with the current collector 50. As shown in FIGS. 2(A) and 2(B), for example, a group of stacked electrolyte layers 30 (their oxide solid electrolytes) are exposed on the outer surface of the solid battery body 1Aa.

[0028] In the solid-state battery body 1Aa, the electrolyte layer 30 includes, for example, LAGP, which is an oxide solid electrolyte. The positive electrode layer 10 includes, for example, LAGP, which is an oxide solid electrolyte, LCPO, which is a positive electrode active material, and a carbon-based conductive additive. The negative electrode layer 20 includes, for example, LAGP, which is an oxide solid electrolyte, anatase TiO2 and orthorhombic Nb2O5, which are negative electrode active materials, and a carbon-based conductive additive. As shown in FIGS. 2(A) and 2(B), the electrolyte layer 30 on the outermost surface of the solid-state battery body 1Aa may be provided with a polarity marker 2 indicating which of the current collector 40 and the current collector 50 is the positive electrode side and which is the negative electrode side. In this example, the polarity marker 2 indicates that the current collector 50 connected to the negative electrode layer 20 is the negative electrode side.

[0029] A method for manufacturing the solid state battery 1A having the configuration shown in FIGS. 2(A) and 2(B) will be described below. (LAGP powder formation) First, the raw materials for LAGP—lithium carbonate (Li2CO3), aluminum oxide (Al2O3), germanium oxide (GeO2), and ammonium dihydrogen phosphate (NH4H2PO4)—are weighed out to a predetermined composition ratio and mixed in a porcelain mortar or ball mill. The resulting mixture is placed in an alumina crucible and calcined at 300–400°C for 3–5 hours. The calcined powder is then melted by heat treatment at 1200–1400°C for 1–2 hours. The melted material is then rapidly cooled and vitrified. This results in the formation of amorphous LAGP powder.

[0030] The resulting amorphous LAGP powder is roughly crushed to a particle size of 200 μm or less, and then further pulverized using a grinding device such as a ball mill to adjust the particle size p (median diameter D50) to the desired value. The particle size p of the LAGP powder for the electrolyte layer is adjusted to, for example, 2 μm≦p≦5 μm. The particle size p of the LAGP powder for the electrode layer is adjusted to, for example, 0.2 μm≦p≦1.0 μm, which is smaller than that for the electrolyte layer, in order to ensure the lithium ion conductivity of the electrode layer by interposing the LAGP powder between the particles of the powdered active material.

[0031] For example, by such a method, LAGP powders to be used for the electrolyte layer 30, the positive electrode layer 10, and the negative electrode layer 20 of a solid state battery 1A as shown in FIG. 2(B) are prepared. (Electrolyte layer formation) As an example, the LAGP powder having a particle size p for the electrolyte layer obtained by the above method is mixed with an organic binder or the like, adjusted to a predetermined thickness, and coated onto a carrier such as a polyethylene terephthalate (PET) film by a doctor blade method or the like to form a flexible electrolyte layer green sheet (also called an "LAGP green sheet"). For example, the electrolyte layer green sheet thus formed is used to form an electrolyte layer 30 as shown in FIG. 2(B).

[0032] As another example, the LAGP powder having a particle size p for the electrolyte layer obtained by the above method is compacted by a uniaxial hydraulic press and then sintered at a temperature of 900°C for 3 hours. This forms an electrolyte layer substrate (also called an "LAGP substrate"). For example, the electrolyte layer substrate thus formed is used to form an electrolyte layer 30 as shown in FIG. 2(B).

[0033] (Formation of positive electrode layer) For example, the LAGP powder having a particle size p for the electrode layer obtained by the above method, the LCPO positive electrode active material, a carbon-based conductive additive, and a binder such as an acrylic resin are mixed, adjusted to a predetermined thickness and amount of active material, and coated on a carrier such as a PET film by a doctor blade method to form a positive electrode layer green sheet. The positive electrode layer green sheet thus formed is used to form the positive electrode layer 10 shown in FIG. 2(B).

[0034] As another example, the LAGP powder having a particle size p for the electrode layer obtained by the above method, the LCPO positive electrode active material, a carbon-based conductive additive, and a binder such as an acrylic resin are mixed to form a paste (or slurry) for the electrode layer. The paste for the electrode layer thus formed is used to form the positive electrode layer 10 as shown in FIG. 2(B).

[0035] (Formation of negative electrode layer) For example, the LAGP powder with particle size p for the electrode layer obtained by the above method, the negative electrode active materials anatase TiO2 and orthorhombic Nb2O5, a carbon-based conductive additive, and a binder such as acrylic resin are mixed and adjusted to a predetermined thickness and active material amount. The mixture is then coated onto a carrier such as a PET film using a doctor blade method or the like to form a negative electrode layer green sheet. The negative electrode active materials anatase TiO2 and orthorhombic Nb2O5 are blended in a weight ratio of 1:1 (the weight ratio of anatase TiO2 to orthorhombic Nb2O5 is 1). For example, a 1:1 mixture of anatase TiO2 and orthorhombic Nb2O5 is used as the negative electrode active material. The negative electrode layer green sheet thus formed is used to form the negative electrode layer 20 shown in FIG. 2(B).

[0036] As another example, the LAGP powder with particle size p for the electrode layer obtained by the above method, the negative electrode active materials anatase TiO2 and orthorhombic Nb2O5, a carbon-based conductive additive, and a binder such as acrylic resin are mixed to form a paste (or slurry) for the negative electrode layer. The negative electrode active materials anatase TiO2 and orthorhombic Nb2O5 are blended in a weight ratio of 1:1 (the weight ratio of orthorhombic Nb2O5 to the weight of anatase TiO2 is 1). For example, a mixture of anatase TiO2 and orthorhombic Nb2O5 in a weight ratio of 1:1 is used as the negative electrode active material. The negative electrode layer paste thus formed is used to form the negative electrode layer 20 shown in FIG. 2(B).

[0037] (Formation of solid-state battery body) For example, a solid state battery body 1Aa as shown in FIG. 2(B) is formed by a green sheet lamination method using a green sheet for an electrolyte layer and a green sheet for positive and negative electrode layers (first formation example shown in FIGS. 3 and 4), or by a screen printing method using a substrate for an electrolyte layer and paste for positive and negative electrode layers (second formation example shown in FIGS. 5 and 6), or by a screen printing method using a green sheet for an electrolyte layer and paste for positive and negative electrode layers (third formation example shown in FIGS. 7 and 8).

[0038] 3 and 4 are diagrams illustrating a first example of forming a solid-state battery body. Each of Fig. 3(A) to Fig. 3(C) shows a perspective view of a main part of the layers included in the solid-state battery body. Fig. 4 shows a cross-sectional view of a main part of the process of stacking the layers included in the solid-state battery body.

[0039] 2(B), electrolyte layers 30 provided above and below the positive electrode layer 10 and electrolyte layers 30 provided above and below the negative electrode layer 20 are formed using electrolyte layer green sheets 31 (LAGP green sheets) having the shape shown in Fig. 3(A). The electrolyte layer green sheets 31 are prepared as they are or by cutting the ones obtained by the above method.

[0040] For the positive electrode layer 10 of the solid-state battery body 1Aa shown in FIG. 2(B), a positive electrode layer green sheet 11 having a shape as shown in FIG. 3(B) (middle view) is used. The positive electrode layer green sheet 11 is prepared as is or after cutting the one obtained by the above method. Furthermore, as the electrolyte layer 30 provided in the same layer as the positive electrode layer 10 of the solid-state battery body 1Aa, an electrolyte layer green sheet 31 having a shape as shown in FIG. 3(B) (upper view), i.e., a shape capable of surrounding the positive electrode layer green sheet 11 except for one end, is prepared. This electrolyte layer green sheet 31 is prepared by cutting the one obtained by the above method. The prepared positive electrode layer green sheet 11 and electrolyte layer green sheet 31 may be combined in advance so that the positive electrode layer green sheet 11 is surrounded by the electrolyte layer green sheet 31 except for one end, as shown in FIG. 3(B) (lower view).

[0041] For the anode layer 20 of the solid-state battery body 1Aa shown in FIG. 2(B), a green sheet for anode layer 21 having a shape as shown in FIG. 3(C) (middle view) is used. The green sheet for anode layer 21 is prepared by cutting or using the green sheet obtained by the above-described method. Furthermore, as the electrolyte layer 30 provided in the same layer as the anode layer 20 of the solid-state battery body 1Aa, a green sheet for electrolyte layer 31 having a shape as shown in FIG. 3(C) (upper view), i.e., a shape capable of surrounding the green sheet for anode layer 21 except for one end portion, is prepared. This green sheet for electrolyte layer 31 is prepared by cutting the green sheet obtained by the above-described method. The prepared green sheet for anode layer 21 and green sheet for electrolyte layer 31 may be combined in advance so that the green sheet for anode layer 21 is surrounded by the green sheet for electrolyte layer 31 except for one end portion, as shown in FIG. 3(C) (lower view).

[0042] The electrolyte layer green sheet 31, the positive electrode layer green sheet 11, and the negative electrode layer green sheet 21 obtained as described above are stacked in the order shown in Fig. 4 and thermocompression bonded. This forms the basic structure (laminate) of the solid state battery body 1Aa. A polarity marker 2 may be provided on the uppermost electrolyte layer green sheet 31.

[0043] For convenience, Fig. 3(B) illustrates a state in which the positive electrode layer green sheet 11 is surrounded by the electrolyte layer green sheet 31 except for one end thereof, but by cutting at a predetermined position after lamination and thermocompression bonding as shown in Fig. 4, the positive electrode layer green sheet 11 may be surrounded by the electrolyte layer green sheet 31 except for one end thereof. Similarly, Fig. 3(C) illustrates a state in which the negative electrode layer green sheet 21 is surrounded by the electrolyte layer green sheet 31 except for one end thereof, but by cutting at a predetermined position after lamination and thermocompression bonding as shown in Fig. 4, the negative electrode layer green sheet 21 may be surrounded by the electrolyte layer green sheet 31 except for one end thereof.

[0044] 5 and 6 are diagrams illustrating a second example of forming a solid-state battery body. Fig. 5(A) to Fig. 5(D) each show a perspective view of a main part in a forming process of layers included in the solid-state battery body. Fig. 6 shows a cross-sectional view of a main part in a stacking process of layers included in the solid-state battery body.

[0045] An electrolyte layer substrate 32 (LAGP substrate) having the shape shown in FIG. 5(A) is prepared by the above-described powder compaction and sintering. A cathode layer paste 12 is applied to a portion of one surface of the electrolyte layer substrate 32 by screen printing, as shown in FIG. 5(B), with a predetermined thickness and active material content. After application, the paste is dried in a dryer at 100°C for 30 minutes to remove the solvent from the applied cathode layer paste 12. An insulating paste, for example, an electrolyte layer paste 33 containing an LAGP oxide solid electrolyte, is applied to the remaining portion of the one surface of the electrolyte layer substrate 32 by screen printing, as shown in FIG. 5(C). After application, the paste is dried in a dryer at 100°C for 30 minutes to remove the solvent from the applied electrolyte layer paste 33.

[0046] Alternatively, the electrolyte layer paste 33 may be applied by screen printing after the positive electrode layer paste 12 is applied by screen printing, and the positive electrode layer paste 12 and the electrolyte layer paste 33 may be dried together to remove the solvent. The positive electrode layer paste 12 and the electrolyte layer paste 33 may be applied by screen printing multiple times. In this case, drying to remove the solvent may be performed after each screen printing of the positive electrode layer paste 12 and the electrolyte layer paste 33, or may be performed all at once after multiple screen printings of the positive electrode layer paste 12 and the electrolyte layer paste 33.

[0047] 5(A) to 5(C), as shown in Fig. 5(D), anode layer paste 22 is applied by screen printing to a portion of the other surface of electrolyte layer substrate 32, with the thickness and amount of active material adjusted to a predetermined value, and an insulating paste, for example, electrolyte layer paste 33, is applied by screen printing to the remaining portion of the surface. After application of anode layer paste 22 and electrolyte layer paste 33, drying is performed in a dryer at a temperature of 100°C for 30 minutes to remove the solvent in the applied anode layer paste 22 and electrolyte layer paste 33.

[0048] Alternatively, the electrolyte layer paste 33 may be applied by screen printing after the negative electrode layer paste 22 is applied by screen printing, and the negative electrode layer paste 22 and the electrolyte layer paste 33 may be dried together to remove the solvent. The negative electrode layer paste 22 and the electrolyte layer paste 33 may be applied by screen printing multiple times. In this case, drying to remove the solvent may be performed after each screen printing of the negative electrode layer paste 22 and the electrolyte layer paste 33, or may be performed all at once after multiple screen printings of the negative electrode layer paste 22 and the electrolyte layer paste 33.

[0049] The laminate 3 as shown in Fig. 5(D) is alternately laminated with the electrolyte layer substrate 32 or the electrolyte layer green sheet 31 as shown in Fig. 6, and is thermocompression bonded. In this way, the basic structure (laminate) of the solid state battery body 1Aa is formed. The uppermost electrolyte layer substrate 32 or electrolyte layer green sheet 31 may be provided with a polarity marker 2.

[0050] 5(B) and 5(C) illustrate, for convenience, a state in which the side surface of the positive electrode layer paste 12 is exposed from one side surface of the electrolyte layer substrate 32 and the electrolyte layer paste 33, but by cutting at a predetermined position after the lamination and thermocompression bonding shown in Fig. 6, a state in which the side surface of the positive electrode layer paste 12 is exposed from one side surface of the electrolyte layer substrate 32 and the electrolyte layer paste 33 may be obtained. Similarly, for convenience, Fig. 5(D) illustrates, for convenience, a state in which the side surface of the negative electrode layer paste 22 is exposed from one side surface of the electrolyte layer substrate 32 and the electrolyte layer paste 33, but by cutting at a predetermined position after the lamination and thermocompression bonding shown in Fig. 6, a state in which the side surface of the negative electrode layer paste 22 is exposed from one side surface of the electrolyte layer substrate 32 and the electrolyte layer paste 33 may be obtained.

[0051] 7 and 8 are diagrams illustrating a third example of forming a solid-state battery body. Fig. 7(A) to Fig. 7(E) each show a perspective view of a main part in a forming process of layers included in the solid-state battery body. Fig. 8 shows a cross-sectional view of a main part in a stacking process of layers included in the solid-state battery body.

[0052] An electrolyte layer green sheet 31 having a shape as shown in FIG. 7(A) is prepared. As shown in FIG. 7(B), a cathode layer paste 12 is applied to a portion of the electrolyte layer green sheet 31 by screen printing, adjusted to a predetermined thickness and amount of active material. After application, the cathode layer paste 12 is dried in a dryer at a temperature of 100°C for 30 minutes to remove the solvent from the applied cathode layer paste 12. As shown in FIG. 7(C), an insulating paste, for example, an electrolyte layer paste 33 is applied to the remaining portion of the electrolyte layer green sheet 31 by screen printing. After application, the cathode layer paste 12 is dried in a dryer at a temperature of 100°C for 30 minutes to remove the solvent from the applied electrolyte layer paste 33.

[0053] Alternatively, the electrolyte layer paste 33 may be applied by screen printing after the positive electrode layer paste 12 is applied by screen printing, and the positive electrode layer paste 12 and the electrolyte layer paste 33 may be dried together to remove the solvent. The positive electrode layer paste 12 and the electrolyte layer paste 33 may be applied by screen printing multiple times. In this case, drying to remove the solvent may be performed after each screen printing of the positive electrode layer paste 12 and the electrolyte layer paste 33, or may be performed all at once after multiple screen printings of the positive electrode layer paste 12 and the electrolyte layer paste 33.

[0054] Similarly, an electrolyte layer green sheet 31 having the shape shown in FIG. 7(A) is prepared, and a negative electrode layer paste 22 is applied to a portion of the electrolyte layer green sheet 31 by screen printing, as shown in FIG. 7(D), with a predetermined thickness and amount of active material adjusted. After application, the negative electrode layer paste 22 is dried in a dryer at a temperature of 100°C for 30 minutes, thereby removing the solvent from the applied negative electrode layer paste 22. An insulating paste, for example, an electrolyte layer paste 33 is applied to the remaining portion of the electrolyte layer green sheet 31 by screen printing, as shown in FIG. 7(E). After application, the negative electrode layer paste 22 is dried in a dryer at a temperature of 100°C for 30 minutes, thereby removing the solvent from the applied electrolyte layer paste 33.

[0055] Alternatively, the electrolyte layer paste 33 may be applied by screen printing after the negative electrode layer paste 22 is applied by screen printing, and the negative electrode layer paste 22 and the electrolyte layer paste 33 may be dried together to remove the solvent. The negative electrode layer paste 22 and the electrolyte layer paste 33 may be applied by screen printing multiple times. In this case, drying to remove the solvent may be performed after each screen printing of the negative electrode layer paste 22 and the electrolyte layer paste 33, or may be performed all at once after multiple screen printings of the negative electrode layer paste 22 and the electrolyte layer paste 33.

[0056] The laminate 4 as shown in Fig. 7(C) and the laminate 5 as shown in Fig. 7(E) are alternately stacked with the electrolyte layer green sheets 31 and thermocompression bonded as shown in Fig. 8. This forms the basic structure (laminate) of the solid state battery body 1Aa. The uppermost electrolyte layer green sheet 31 may be provided with a polarity marker 2.

[0057] 7(B) and 7(C) illustrate, for convenience, a state in which the side surface of the positive electrode layer paste 12 is exposed from one side surface of the electrolyte layer green sheet 31 and the electrolyte layer paste 33, but by cutting at a predetermined position after lamination and thermocompression bonding as shown in Fig. 8, a state in which the side surface of the positive electrode layer paste 12 is exposed from one side surface of the electrolyte layer green sheet 31 and the electrolyte layer paste 33 may be obtained. Similarly, FIG. 7(D) and 7(E) illustrate, for convenience, a state in which the side surface of the negative electrode layer paste 22 is exposed from one side surface of the electrolyte layer green sheet 31 and the electrolyte layer paste 33, but by cutting at a predetermined position after lamination and thermocompression bonding as shown in Fig. 8, a state in which the side surface of the negative electrode layer paste 22 is exposed from one side surface of the electrolyte layer green sheet 31 and the electrolyte layer paste 33 may be obtained.

[0058] (Firing) 9A and 9B are diagrams illustrating the firing of the basic structure of a solid-state battery body. Fig. 9A shows a cross-sectional view of a main part of the basic structure of a solid-state battery body. Fig. 9B shows a cross-sectional view of a main part of the firing process of the basic structure of a solid-state battery body.

[0059] 3 and 4, or the method shown in Figures 5 and 6, or the method shown in Figures 7 and 8, a laminate 100, which is the basic structure of a solid battery body 1Aa, is obtained as shown in Figure 9(A). The laminate 100 includes an electrolyte layer 30 before firing (corresponding to the above-mentioned electrolyte layer green sheet 31, electrolyte layer substrate 32, or electrolyte layer paste 33), a positive electrode layer 10 before firing (corresponding to the above-mentioned positive electrode layer green sheet 11 or positive electrode layer paste 12), and a negative electrode layer 20 before firing (corresponding to the above-mentioned negative electrode layer green sheet 21 or negative electrode layer paste 22).

[0060] 9(B), the obtained laminate 100 is carried into a firing furnace 120. Then, the carried-in laminate 100 is fired in the firing furnace 120 by heating in an oxidizing atmosphere at a temperature of 500°C for 7 hours for desolvation, and further fired in an oxidizing atmosphere at a temperature of 600°C to 625°C for 2 hours for sintering. This forms a solid-state battery body 1Aa having a fired electrolyte layer 30, a positive electrode layer 10, and a negative electrode layer 20.

[0061] Here, the negative electrode layer 20 of the laminate 100 before firing contains anatase TiO2 and orthorhombic Nb2O5 as negative electrode active materials. If the negative electrode layer 20 contains only anatase TiO2 out of anatase TiO2 and orthorhombic Nb2O5 as the negative electrode active material, the sinterability and sintered density of the negative electrode layer 20 may decrease due to aggregation of TiO2 during firing in an oxidizing atmosphere as described above. In contrast, if the negative electrode layer 20 contains orthorhombic Nb2O5 in addition to anatase TiO2 as the negative electrode active material, the orthorhombic Nb2O5 functions not only as the negative electrode active material but also as a sintering aid, thereby suppressing the decrease in the sinterability and sintered density of the negative electrode layer 20 due to aggregation of TiO2 during firing in an oxidizing atmosphere as described above. In the negative electrode layer 20 of the sintered body after firing, anatase TiO2 and orthorhombic Nb2O5 coexist in the form of their respective crystal structures.

[0062] (Formation of current collector layer) After the solid-state battery body 1Aa is formed, a current collector 40 is formed from a silver (Ag) paste or the like at one end where the positive electrode layer 10 is exposed. Similarly, a current collector 50 is formed from an Ag paste or the like at the other end of the solid-state battery body 1Aa where the negative electrode layer 20 is exposed. Note that, in addition to Ag paste, a conductive paste containing conductive particles such as various metal particles or carbon particles can also be used for the current collectors 40 and 50. A conductive paste such as Ag paste is applied to both ends of the solid-state battery body 1Aa, and the conductive particles such as Ag in the conductive paste are sintered by firing to form the current collectors 40 and 50. Alternatively, the current collectors 40 and 50 may be formed by vapor deposition of various metals using a sputtering method or the like. A current collector 40 connected to the positive electrode layer 10 is formed at one end of the solid battery body 1Aa, and a current collector 50 connected to the negative electrode layer 20 is formed at the other end of the solid battery body 1Aa, thereby forming a solid battery 1A having a configuration as shown in Figures 2(A) and 2(B).

[0063] [Characteristics of solid-state batteries] Next, the evaluation results of the characteristics of the solid-state battery will be described. (Sinterability evaluation) For a sintered solid-state battery 1A (FIG. 2) equipped with a positive electrode layer 10 containing LCPO as the positive electrode active material and a negative electrode layer 20 containing anatase TiO2 and orthorhombic Nb2O5 in a weight ratio of 1:1 (weight of anatase TiO2:weight of orthorhombic Nb2O5=1:1) as negative electrode active materials, the cross section of the negative electrode layer 20 was observed using a scanning electron microscope (SEM). For comparison, a sintered solid-state battery equipped with a positive electrode layer containing LCPO as the positive electrode active material and a negative electrode layer containing only anatase TiO2 as the negative electrode active material was also similarly observed using SEM.

[0064] Figure 10 shows an example of an SEM image of a cross section of the negative electrode layer after firing of a solid-state battery containing anatase TiO2 and orthorhombic Nb2O5 (weight ratio 1:1) as the negative electrode active material. Figure 11 shows an example of an SEM image of a cross section of the negative electrode layer after firing of a solid-state battery containing only anatase TiO2 as the negative electrode active material.

[0065] 10 and 11, the negative electrode layer 20 (FIG. 10) of the solid-state battery 1A (FIG. 2) containing anatase TiO2 and orthorhombic Nb2O5 (weight ratio 1:1) as the negative electrode active material exhibited better sinterability than the negative electrode layer (FIG. 11) of the solid-state battery containing only anatase TiO2 as the negative electrode active material. For example, when the sintered density was calculated using the SEM images shown in FIGS. 10 and 11, the negative electrode layer (FIG. 11) of the solid-state battery containing only anatase TiO2 as the negative electrode active material had a sintered density of 82%, whereas the negative electrode layer 20 (FIG. 10) of the solid-state battery 1A containing anatase TiO2 and orthorhombic Nb2O5 as the negative electrode active material achieved a sintered density of over 82%, even reaching a high sintered density of 91% or more. The sintered density was calculated by image processing the SEM image to calculate the percentage of non-void areas within the SEM image.

[0066] 10 and 11, it was confirmed that in the solid state battery 1A in which both anatase TiO2 and orthorhombic Nb2O5 are used as the negative electrode active materials in the negative electrode layer 20, the decrease in the sintered density of the negative electrode layer 20 is suppressed and good sinterability is achieved.

[0067] (Charge / discharge evaluation) Charge-discharge measurements were performed under the following conditions on a solid-state battery 1A equipped with a positive electrode layer 10 containing LCPO as the positive electrode active material and a negative electrode layer 20 containing anatase TiO2 and orthorhombic Nb2O5 in a weight ratio of 1:1 (weight of anatase TiO2:weight of orthorhombic Nb2O5=1:1) as the negative electrode active material. For comparison, charge-discharge measurements were also performed under the following conditions on a solid-state battery equipped with a positive electrode layer containing LCPO as the positive electrode active material and a negative electrode layer containing only anatase TiO2 as the negative electrode active material.

[0068] The conditions for the charge / discharge measurements were as follows: Charging was performed using constant current (CC) charging with a cutoff voltage of 3.6 V or a cutoff charge capacity of 230 μAh, and the current values were charge rates of 0.1 C (20 μA), 0.4 C (80 μA), and 2 C (400 μA). Discharging was performed using CC discharging with a cutoff voltage of 0.5 V, and the current values were the same as the charge rates, with discharge rates of 0.1 C (20 μA), 0.4 C (80 μA), and 2 C (400 μA). A charge rate of 1 C is defined as the current magnitude that fully charges the theoretical battery capacity in 1 hour, and a discharge rate of 1 C is defined as the current magnitude that fully discharges the theoretical battery capacity in 1 hour. The charge / discharge measurements were performed in a thermostatic chamber at 20°C.

[0069] The results of charge / discharge measurements performed under these conditions are shown in Figures 12 and 13. Figure 12 shows an example of a charge / discharge curve for a solid-state battery containing anatase TiO2 and orthorhombic Nb2O5 (weight ratio 1:1) as the negative electrode active material. Figure 13 shows an example of a charge / discharge curve for a solid-state battery containing only anatase TiO2 as the negative electrode active material.

[0070] 12 and 13, the negative electrode layer 20 of the solid state battery 1A containing anatase TiO2 and orthorhombic Nb2O5 (weight ratio 1:1) as the negative electrode active material exhibited better charge / discharge characteristics at charge / discharge rates of 0.1C (20 μA), 0.4C (80 μA), and 2C (400 μA) than the negative electrode layer of the solid state battery containing only anatase TiO2 as the negative electrode active material.

[0071] The discharge capacity was evaluated when the charge / discharge rate was changed continuously in a predetermined cycle from 0.1 C (20 μA), 0.4 C (80 μA), 2 C (400 μA), and 0.1 C (20 μA). The results are shown in Figure 14. Figure 14 shows the change in discharge capacity versus charge / discharge rate for a solid-state battery containing anatase TiO and orthorhombic NbO (1:1 by weight) as the negative electrode active material, and a solid-state battery containing only anatase TiO as the negative electrode active material.

[0072] As shown in FIG. 14, the negative electrode layer 20 of the solid state battery 1A containing anatase TiO2 and orthorhombic Nb2O5 (weight ratio 1:1) as the negative electrode active material exhibited a higher discharge capacity at all charge / discharge rates than the negative electrode layer of the solid state battery containing only anatase TiO2 as the negative electrode active material.

[0073] 12 to 14, it was confirmed that the solid state battery 1A in which both anatase TiO2 and orthorhombic Nb2O5 were used as the negative electrode active materials in the negative electrode layer 20 exhibited improved rate characteristics. (Consideration) 10 and 11, the solid state battery 1A, in which both anatase TiO2 and orthorhombic Nb2O5 are used as the negative electrode active materials in the negative electrode layer 20, exhibits improved sinterability compared to the case where only anatase TiO2 is used. 12 to 14 show that the solid state battery 1A, in which both anatase TiO2 and orthorhombic Nb2O5 are used as the negative electrode active materials in the negative electrode layer 20, exhibits improved rate characteristics compared to the case where only anatase TiO2 is used, and consistent results are obtained that show that the resistance is reduced due to the improved sinterability.

[0074] [Other configuration examples] In the above explanation, a chip-type solid state battery 1A having an anode layer 20 containing anatase TiO2 and orthorhombic Nb2O5 has been exemplified, but it is also possible to form batteries having various shapes, such as thin, coin, button, rectangular, and cylindrical, having an anode layer 20 containing anatase TiO2 and orthorhombic Nb2O5.

[0075] 15A and 15B are diagrams showing another example of the configuration of a solid-state battery. FIG. 15A is a schematic perspective view of a main part of an example of a solid-state battery. FIG. 15B is a schematic cross-sectional view of a main part of an example of a solid-state battery. FIG. 15B is an example of a cross section taken along plane P2 of FIG. 15A.

[0076] The solid-state battery 1B shown in FIGS. 15(A) and 15(B) is an example of a thin battery. The solid-state battery 1B has an exterior body 200, and terminals 210 and 220 that protrude to the outside from the exterior body 200. The exterior body 200 may be, for example, a film-, bag-, or box-shaped body made of a material such as resin, ceramic, or insulatingly coated metal. The solid-state battery main body 1Ba is housed inside the exterior body 200. The solid-state battery 1B may have a structure in which the solid-state battery main body 1Ba, which is coated with a predetermined insulating material (for example, an oxide solid electrolyte), is further coated with an exterior body 200 that is, for example, a film-, bag-, or box-shaped.

[0077] The solid-state battery body 1Ba includes a positive electrode layer 10, a negative electrode layer 20, and an electrolyte layer 30 disposed therebetween. The solid-state battery body 1Ba further includes a current collector 40 disposed on the positive electrode layer 10, and a current collector 50 disposed on the negative electrode layer 20. The electrolyte layer 30, the positive electrode layer 10, the negative electrode layer 20, and the current collector 40 and the current collector 50 of the solid-state battery body 1Ba are made of the same materials as those described for the solid-state battery body 1Aa. A terminal 210 is connected to the current collector 40 on the positive electrode layer 10 side by a method such as bonding or welding, and a terminal 220 is connected to the current collector 50 on the negative electrode layer 20 side by a method such as bonding or welding. The solid-state battery body 1Ba is housed inside an exterior body 200 so that the tips of the terminals 210 and 220 are exposed to the outside.

[0078] In the solid-state battery 1B, the use of both anatase TiO2 and orthorhombic Nb2O5 as the negative electrode active materials in the negative electrode layer 20 suppresses a decrease in the sinterability and sintered density of the negative electrode layer 20 obtained by firing in an oxidizing atmosphere, and effectively suppresses an increase in the resistance of the negative electrode layer 20 and a decrease in the energy density of the solid-state battery 1B. A thin solid-state battery 1B is realized that includes the negative electrode layer 20 and is capable of achieving excellent battery performance.

[0079] 16A and 16B are diagrams showing still another example of the configuration of a solid-state battery. Fig. 16A and Fig. 16B are schematic perspective views of the main parts of an example of a solid-state battery. Fig. 16C is a schematic cross-sectional view of the main parts of an example of a solid-state battery.

[0080] The solid-state battery 1C shown in FIG. 16(A) is an example of a coin-type or button-type battery, and includes a positive electrode layer 10, a negative electrode layer 20, and an electrolyte layer 30 provided therebetween. For example, as shown in FIG. 16(B), the solid-state battery 1C may be configured such that a current collector 40 and a current collector 50 are provided on the positive electrode layer 10 and the negative electrode layer 20, respectively. For example, as shown in FIG. 16(C), the solid-state battery 1C may be covered with a conductive exterior body 201 that is connected to the positive electrode layer 10 (or a current collector provided thereon, not shown) but is not connected to the negative electrode layer 20 (or a current collector provided thereon, not shown).

[0081] The electrolyte layer 30, the positive electrode layer 10, and the negative electrode layer 20, and further the current collectors 40 and 50 of the solid battery 1C are made of the same materials as those described for the solid battery body 1Aa. In the solid-state battery 1C, the use of both anatase TiO2 and orthorhombic Nb2O5 as the negative electrode active materials in the negative electrode layer 20 suppresses a decrease in the sinterability and sintered density of the negative electrode layer 20 obtained by firing in an oxidizing atmosphere, and effectively suppresses an increase in the resistance of the negative electrode layer 20 and a decrease in the energy density of the solid-state battery 1C. A coin-type or button-type solid-state battery 1C is realized that includes the negative electrode layer 20 and is capable of achieving excellent battery performance.

[0082] [Variations] In the above description, amorphous LAGP has been exemplified as the oxide solid electrolyte used in the electrolyte layer 30, the positive electrode layer 10, and the negative electrode layer 20. However, the electrolyte layer 30, the positive electrode layer 10, and the negative electrode layer 20 may each contain crystalline LAGP in addition to amorphous LAGP.

[0083] The LAGP of the electrolyte layer 30 contains Li 1.5 Al 0.5 Ge 1.5 Not limited to the composition of (PO4)3, Li 1.4 Al 0.4 Ge 1.6 NASICON-type LAGP with other compositions such as (PO4)3 may also be used. In addition to LAGP, the electrolyte layer 30 may also include NASICON-type LATP (general formula Li1+z Al z Ti 2-z (PO4)3, where 0 < z ≤ 1, is one kind of Li 1.3 Al 0.3 Ti 1.7 (PO4)3, garnet-type lithium lanthanum zirconate (Li7La3Zr2O 12 , hereinafter referred to as "LLZ"), perovskite-type lithium lanthanum titanate (Li 0.5 La 0.5 TiO3, hereinafter referred to as "LLT"), partially nitrided lithium phosphate (γ-Li3PO4, hereinafter referred to as "LiPON"), etc., other oxide solid electrolytes may also be used.

[0084] In the positive electrode layer 10 and the negative electrode layer 20, other oxide solid electrolytes such as LAGP, LATP, LLZ, LLT, LiPON, etc. may also be used as long as a certain performance is achieved in combination with the active material used.

[0085] For example, in the electrolyte layer 30, the positive electrode layer 10, and the negative electrode layer 20, a NASICON-type oxide solid electrolyte represented by the general formula Li 1+y Al y M 2-y (PO4)3 is suitable. Here, the composition ratio y is in the range of 0 < y ≤ 1, and M is one or both of germanium (Ge) and titanium.

[0086] In the electrolyte layer 30, the positive electrode layer 10, and the negative electrode layer 20, the same kind of oxide solid electrolyte may be used for each other, or different kinds of oxide solid electrolytes may be used for each other. In the electrolyte layer 30, the positive electrode layer 10, and the negative electrode layer 20, one kind of oxide solid electrolyte may be used for each, or two or more kinds of oxide solid electrolytes may be used for each.

[0087] In the above description, LCPO is exemplified as the positive electrode active material contained in the positive electrode layer 10, but lithium cobalt phosphate (LiCoPO4), lithium vanadium phosphate (Li3V2(PO4)3), etc. may also be used as the positive electrode active material. The positive electrode layer 10 may use one type of material as the positive electrode active material, or two or more types of materials. [Explanation of symbols]

[0088] 1,1A,1B,1C solid state battery 1Aa, 1Ba solid-state battery body 2 polarity markers 3,4,5 laminate 10 Positive electrode layer 11 Green sheet for positive electrode layer 12 Positive electrode layer paste 20 negative electrode layer 21 Green sheet for negative electrode layer 22 Negative electrode layer paste 30 Electrolyte layer 30a,30b side 31 Green sheet for electrolyte layer 32 Substrate for electrolyte layer 33 Electrolyte layer paste 40,50 Current collector 100 laminate 120 Kiln 200, 201 Exterior body 210,220 terminals

Claims

1. a positive electrode layer including a first oxide solid electrolyte and a positive electrode active material; a negative electrode layer including a second oxide solid electrolyte and a negative electrode active material; an electrolyte layer provided between the positive electrode layer and the negative electrode layer, the electrolyte layer including a third oxide solid electrolyte; and The negative electrode active material is anatase type TiO ２ and orthorhombic Nb ２ O ５ Including, A solid-state battery, wherein the ratio of the weight of the orthorhombic Nb 2 O 5 to the weight of the anatase TiO 2 contained in the negative electrode active material is 1.

2. 2. The solid-state battery according to claim 1, wherein the negative electrode layer is a sintered body having a sintered density of more than 82%, and the sintered density is determined by calculating the proportion of non-void areas in a scanning electron microscope image through image processing of a scanning electron microscope image of a cross section of the negative electrode layer.

3. Among the first oxide solid electrolyte, the second oxide solid electrolyte, and the third oxide solid electrolyte, at least the second oxide solid electrolyte contains Li １．５ Al ０．５ Ge １．５ (P.O. ４ ) ３ The solid-state battery according to claim 1 or 2, comprising:

4. The positive electrode active material is Li ２ CoP ２ O ７ 4. The solid-state battery according to claim 1, further comprising:

5. a positive electrode layer including a first oxide solid electrolyte and a positive electrode active material; a negative electrode layer including a second oxide solid electrolyte and a negative electrode active material; an electrolyte layer provided between the positive electrode layer and the negative electrode layer, the electrolyte layer including a third oxide solid electrolyte; forming a laminate having firing the laminate in an oxidizing atmosphere; Including, The negative electrode active material is anatase type TiO ２ and orthorhombic Nb ２ O ５ Including, A method for producing a solid-state battery, wherein the ratio of the weight of the orthorhombic Nb 2 O 5 to the weight of the anatase TiO 2 contained in the negative electrode active material is 1.

6. 6. The method for manufacturing a solid-state battery according to claim 5, wherein the negative electrode layer of the laminate fired in the oxidizing atmosphere has a sintered density of more than 82%, and the sintered density is determined by calculating the proportion of non-void portions in a scanning electron microscope image by image processing of a scanning electron microscope image of a cross section of the negative electrode layer.

Images