Electrode for solid-state battery and method for manufacturing the same, solid-state battery, battery package

Abstract

Provided is a solid-state battery electrode that has better performance. This solid-state battery electrode comprises: a plurality of active material particles each having a porous structure including pores therein; a binding material that is a hydrophilic organic compound provided in the gaps between the plurality of active material particles; and an inorganic solid-state electrolyte that is soluble at a temperature below the volatilization temperature of the binder and is impregnated into the pores.

Description

[Technical Field]

[0001] The present technology relates to an electrode for a solid-state battery having a solid electrolyte, a manufacturing method thereof, and a solid-state battery and a battery package including the electrode for the solid-state battery. [Background technology]

[0002] Due to the widespread use of various electronic devices such as mobile phones, secondary batteries have been developed as power sources that are small, lightweight, and capable of obtaining high energy density. These secondary batteries include a positive electrode, a negative electrode, and an electrolyte housed inside an exterior member. In recent years, solid-state batteries, which are secondary batteries that include a solid electrolyte instead of a liquid or gel electrolyte containing an organic solvent, have been developed (see, for example, Patent Document 1). 1 and non-patent literature 1 reference). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-238925 [Non-patent literature]

[0004] [Non-Patent Document 1] “Electrolyte melt infiltration for scalable manufacturing of inorganic all-solid-state lithium-ion batteries”, Yiran Xiao et al., Nature Materials, 20, 984 (2021) Summary of the Invention

[0005] As described in the above-mentioned prior art documents, various studies have been conducted to improve the performance of solid-state batteries, but there is still room for improvement in the performance of solid-state batteries.

[0006] Therefore, there is a demand for solid-state battery electrodes that can be used in solid-state batteries with better performance.

[0007] An electrode for a solid state battery according to one embodiment of the present disclosure includes a plurality of active material particles, each having a porous structure including pores therein; a binder that is a hydrophilic organic compound provided in the gaps between the plurality of active material particles; and an inorganic solid electrolyte that is soluble at a temperature below the volatilization temperature of the binder and that is impregnated into the pores.

[0008] According to an embodiment of the solid-state battery electrode of the present disclosure, the pores of the active material particles are impregnated with an inorganic solid electrolyte that is soluble at a temperature below the volatilization temperature of the binder, which is a hydrophilic organic compound. This increases the area of the interface where the active material particles contact the inorganic solid electrolyte, thereby improving the conductivity of the electrode reactant. Therefore, when applied to a solid-state battery, superior performance can be achieved, such as support for rapid charging and high output.

[0009] Note that the effects of the present disclosure are not necessarily limited to the effects described here, but may be any of a series of effects related to the present disclosure described below. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view schematically illustrating a configuration example of an electrode for a solid state battery according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a flow chart showing an example of a manufacturing process for the electrode for the solid state battery shown in FIG. [Figure 3] FIG. 3 is a schematic cross-sectional view showing the configuration of a battery package according to a second embodiment of the present disclosure. [Figure 4] FIG. 4 is a cross-sectional view illustrating the configuration of the solid-state battery shown in FIG. [Figure 5] FIG. 5 is a cross-sectional view showing a structural example of the solid electrolyte layer shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. The description will be made in the following order. 0. Overview of this technology 1. First embodiment 1.1 Structure of electrodes for solid-state batteries 1.2 Manufacturing method for electrodes for solid-state batteries 1.3 Functions and effects of electrodes for solid-state batteries 2. Second embodiment 2.1 Battery package 2.2 Solid state batteries 2.3 Covering 2.4 Battery package manufacturing method 2.5 Action and effect 3. Battery package applications 4. Working Example In addition, the "solid-state battery" in the present disclosure refers to a battery whose components are solid. For example, the "solid-state battery" in the present disclosure is a stacked solid-state battery formed by stacking multiple layers. The multiple layers are made of, for example, a sintered body. The "solid-state battery" in the present disclosure includes not only secondary batteries that can be repeatedly charged and discharged, but also primary batteries that can only be discharged.

[0012] [0. Summary of this Disclosure] First, an overview of the present disclosure will be described. Various studies have been conducted to improve the performance of solid-state batteries. Because solid-state batteries contain a solid electrolyte, they generally have superior high-temperature resistance and higher safety compared to batteries that use liquid electrolytes.

[0013] To accommodate even more rapid charge / discharge of secondary batteries, possible measures include using an active material with a larger surface area and improving the ionic conductivity of the active material and electrolyte. It is generally known that the larger the interface area between the active material and the electrolyte through which the electrode reactant (e.g., lithium) passes, i.e., the larger the reaction area, the lower the reaction resistance of the electrode reactant and the higher the rapid chargeability. Unlike liquid electrolytes, which easily penetrate into the electrode, solid electrolytes tend to come into point contact with the solid active material. In other words, the interface area between the solid electrolyte and the active material is smaller than the interface area between the liquid electrolyte and the active material.

[0014] Therefore, in the above Patent Document 1, in order to improve the contact between the electrode and the solid electrolyte, a garnet-based material (Li7La3Zr2O 12 ) inorganic solid electrolyte, interface formation In this study, a polyethylene oxide-based polymer solid electrolyte, which has excellent ionic conductivity, is mixed into the cathode. This achieves both ionic conductivity and interface formation. However, the polymer solid electrolyte must be responsible for ionic conduction in the voids within the electrode, where inorganic solid electrolytes cannot penetrate, making it difficult to improve the ionic conductivity of lithium ions. As a solution to this problem, ionic conductivity is improved by controlling the crystal orientation of the positive electrode active material to a plane that facilitates lithium ion migration. However, special crystal orientation control is not only disadvantageous in terms of cost and process, but also slows the migration of lithium ions within the crystal, limiting the improvement effect. Furthermore, polymer solid electrolytes such as polyethylene oxide-based polymers are inherently flammable, making them less safe.

[0015] In addition, in the above-mentioned Non-Patent Document 1, in order to improve the contact between the electrode and the solid electrolyte, Li 1.9 OHCl 0.9 In this method, a solid electrolyte composed of the above is melted at 300°C, the melted electrolyte is impregnated into an electrode, and then cooled and solidified. However, in Non-Patent Document 1, the impregnation of the melted electrolyte is improved by performing surface treatment on the active material, binder, and conductive additive by the ALD method, which is cumbersome.

[0016] In view of the above circumstances, the present applicant proposes an electrode for a solid state battery having higher ionic conductivity, and a solid state battery using the electrode, as described below.

[0017] 1. First Embodiment 1.1 Structure of electrodes for solid-state batteries A solid state battery electrode 1 according to a first embodiment of the present technology will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view illustrating a configuration example of the solid state battery electrode 1. The solid state battery electrode 1 includes a plurality of active material particles 2, a resin 3, and an inorganic solid electrolyte 4.

[0018] The active material particles 2 are not particularly limited, but include a positive electrode material or a negative electrode material capable of absorbing and releasing an electrode reactant such as lithium ions. The active material particles 2 have a porous structure containing voids V2 therein. The shape of the voids V2 is not particularly limited. The dimensions of the voids V2 are preferably 10 nm or more and 500 nm or less. The median diameter D50 of the active material particles 2 can be 3 μm or more and 30 μm or less.

[0019] Resin 3 is a binder provided in the gaps between the active material particles 2 so as to connect the active material particles 2 together. Resin 3 is a hydrophilic organic compound. Resin 3 is an organic compound having a functional group containing OH at its terminal, specifically a hydroxyl group or a carboxyl group. Examples of organic compounds having such a functional group containing OH at its terminal include polyacrylic acid resin, polyvinyl alcohol resin, cellulose resin (carboxymethyl cellulose, ethyl cellulose, methyl cellulose, hydroxyethyl cellulose, etc.), and phenol resin. Resin 3 may also be a hydrophilic organic compound other than those mentioned above. Specifically, resin 3 may be an acrylamide resin, an ester resin (methyl methacrylate, vinyl acetate, etc.), an epoxy resin (bisphenol A diglycidyl ether, etc.), or a melamine resin.

[0020] The inorganic solid electrolyte 4 is meltable at a temperature below the volatilization temperature of the resin 3 and is impregnated into the pores V2. The inorganic solid electrolyte 4 may also be provided so as to fill the gaps between the active material particles 2. The inorganic solid electrolyte 4 may be meltable at a temperature of, for example, 200°C or higher and 400°C or lower. The inorganic solid electrolyte 4 contains a lithium salt containing at least one element selected from the group consisting of boron (B), carbon (C), sulfur (S), and chlorine (Cl). Specifically, the inorganic solid electrolyte 4 may contain at least one of Li2CO3, Li2SO4, Li3BO3, Li3OCl, and Li2OHCl as its main constituent material. The inorganic solid electrolyte 4 may also contain a lithium salt in which the chlorine (Cl) in Li3OCl or Li2OHCl is substituted with fluorine (F), bromine (Br), or iodine (I). Specifically, the inorganic solid electrolyte 4 may contain at least one of Li3OF, Li3OBr, Li3OI, Li2OHF, Li2OHBr, and Li2OHI. Furthermore, the inorganic solid electrolyte 4 may contain a sulfide (Li7PS6 having an argyrodite structure, or one of its sulfides). Materials with substituted Li6PS5Cl and Li6PS5Br, etc., and Li with a silicone structure 10 GeP2S 12 and materials that have been partially substituted (e.g., Li 10 SiP2S 12 and Li 9.54 Si 1.74 P 1.44 S 11.7 C l0.3 The inorganic solid electrolyte 4 may contain a plurality of the above-mentioned constituent materials. The inorganic solid electrolyte 4 desirably does not have a particle interface therein. This is to obtain better conductivity as the solid-state battery electrode 1. The inorganic solid electrolyte 4 is obtained, for example, by melting the above-mentioned lithium salt to cause a lithium molten salt to penetrate into the pores V2 of the plurality of active material particles 2 and the gaps between the plurality of active material particles 2, followed by crystallization.

[0021] While it is desirable that all of the pores V2 and gaps between the active material particles 2 be filled with the inorganic solid electrolyte 4 and the resin 3 throughout the solid-state battery electrode 1, voids may be present in some areas of the solid-state battery electrode 1. However, the porosity, which is the ratio of the total area occupied by voids to the total area of any cross-section of the solid-state battery electrode 1, should be less than 5%. The porosity can be calculated using image processing software, such as a scanning electron microscope (SEM) image of any cross-section of the solid-state battery electrode 1. Specifically, using public domain image processing software like ImageJ, the total area of the SEM image of any cross-section image (SEM image) of the solid-state battery electrode 1 is calculated using "Set Measurement." Next, the contrast area corresponding to the voids is determined using "Threshold." The "area of the contrast area corresponding to the voids" is calculated using "Limit to Threshold" in "Set Measurement." The porosity is calculated as "area of the contrast area corresponding to the voids" / "total area of the SEM image" x 100 (%).

[0022] Furthermore, the weight ratio of the resin 3 to the total weight of the solid battery electrode 1 excluding the inorganic solid electrolyte 4 is preferably 3% or less.

[0023] <1.2 Manufacturing method of solid state battery electrode 1> Next, an example of a method for manufacturing the electrode 1 for a solid battery will be described with reference to FIG. 2. FIG. 2 is a flow chart showing an example of a manufacturing process for the electrode 1 for a solid battery. The electrode 1 for a solid battery can be formed, for example, by a green sheet method using a green sheet. One manufacturing method will be described below as an example, but the present disclosure is not limited to the manufacturing method described below. Furthermore, the chronological matters such as the order of description below are merely for the convenience of explanation, and the present disclosure is not limited to those matters.

[0024] First, there is a hole inside V2A slurry is formed by mixing active material particles having a porous structure containing the active material with a resin and a solvent (step S101). When forming the slurry, any additives such as a conductive additive may be added. As the resin, a hydrophilic organic compound having a functional group containing OH at the terminal is used.

[0025] Next, the slurry is applied onto the film, and then the applied slurry is dried in an oven or the like to form a green sheet (step S102). The film onto which the slurry is applied can be a release film made of polyethylene terephthalate (PET), a metal foil, or the like.

[0026] Next, the prepared green sheet is impregnated with an inorganic solid electrolyte dissolved at a temperature below the volatilization temperature of the resin, for example by dripping it (step S103). This allows the molten inorganic solid electrolyte to penetrate into the gaps between the active material particles 2 and the pores V2 of the active material particles 2. As the molten inorganic solid electrolyte, a lithium molten salt containing at least one of Li2CO3, Li2SO4, Li3BO3, Li3OCl, and Li2OHCl is preferably used. Finally, a drying process is performed to crystallize the molten inorganic solid electrolyte.

[0027] This completes the production of the electrode 1 for a solid state battery.

[0028] <1.3 Actions and effects of electrodes for solid-state batteries> According to the solid state battery electrode 1 of this embodiment, the pores V2 of the active material particles 2 are impregnated with an inorganic solid electrolyte 4 that is soluble at a temperature below the volatilization temperature of the resin 3, which is a hydrophilic organic compound. This increases the area of the interface where the active material particles 2 and the inorganic solid electrolyte 4 contact each other, improving the conductivity of the electrode reactant (lithium ions). Therefore, when applied to a solid state battery, superior performance can be achieved, such as compatibility with rapid charging and high output.

[0029] In the solid-state battery electrode 1, the resin 3 is a hydrophilic organic compound, so good wettability between the resin 3 and the inorganic solid electrolyte 4 can be achieved without surface treatment of the active material, for example, by the ALD method. Therefore, the overall porosity can be made less than 5%. In contrast, if a binder that does not contain OH groups, such as PVDF or PTFE, is used, the binder will alienate the inorganic solid electrolyte 4 due to the influence of polarity, resulting in a porosity of 5% or more. This may result in a decrease in the conductivity of the electrode reactant (lithium ion). In the solid-state battery electrode 1, the use of a hydrophilic organic compound improves the wettability between the resin 3 and the inorganic solid electrolyte 4, thereby achieving good conductivity.

[0030] Furthermore, the solid state battery electrode 1 uses an inorganic solid electrolyte 4 that can dissolve at a temperature below the volatilization temperature of the resin 3, and therefore can achieve higher chemical and thermal stability than when an organic solid electrolyte is used.

[0031] Furthermore, in the solid state battery electrode 1, the lithium salt contained in the inorganic solid electrolyte 4 can be melted and impregnated into the active material particles 2, and then crystallized. This makes it difficult for interfaces between particles to occur in the inorganic solid electrolyte 4. By reducing the interfaces between particles of the inorganic solid electrolyte 4 that reduce ionic conductivity, good electrical conductivity can be ensured.

[0032] 2. Second Embodiment <2.1 Battery package 100> Next, a battery package 100 according to a second embodiment of the present disclosure will be described. FIG. 3 is a schematic cross-sectional view illustrating the overall configuration of the battery package 100. The battery package 100 includes a solid-state battery 101 and a covering 102 that covers the solid-state battery 101. The covering 102 protects the solid-state battery 101 from the external environment. The covering 102 prevents, for example, water vapor from penetrating into the solid-state battery 101. The solid-state battery 101 will be described below, followed by the covering 102. "Water vapor" here refers to moisture, such as water vapor in the atmosphere, and in a preferred embodiment, refers to moisture that includes not only water vapor in gas form but also liquid water. Preferably, such a moisture-impermeable solid-state battery 101 is packaged to be suitable for substrate mounting, particularly for surface mounting.

[0033] <2.2 Solid state battery 101> FIG. 4 is a schematic cross-sectional view illustrating the configuration of a solid-state battery 101. As illustrated in FIGS. 3 and 4 , the solid-state battery 101 includes a laminate 5, a positive electrode terminal 6, and a negative electrode terminal 7. The positive electrode terminal 6 and the negative electrode terminal 7 are disposed opposite each other with the laminate 5 interposed therebetween. As illustrated in FIG. 4 , the laminate 5 includes a positive electrode layer 10, a negative electrode layer 20, and a solid electrolyte layer 30 stacked in the Z-axis direction. The solid electrolyte layer 30 is interposed between the positive electrode layer 10 and the negative electrode layer 20 in the Z-axis direction, which is the stacking direction. Specifically, the solid-state battery 101 has a structure in which a unit U, which includes a negative electrode layer 20, a solid electrolyte layer 30, a positive electrode layer 10, and a solid electrolyte layer 30 stacked in this order, is repeatedly stacked in the Z-axis direction. Note that FIG. 4 illustrates the solid-state battery 101 including two units U, but the solid-state battery 101 is not limited to this embodiment and may include three or more units U. The solid-state battery 101 may further include blank layers 41 and 42, which are electronic insulating layers. The blank layer 41 is provided in the same layer as a portion of the positive electrode layer 10. The blank layer 42 is provided in the same layer as a portion of the negative electrode layer 20. Each layer constituting the solid-state battery 101, i.e., the positive electrode layer 10, the negative electrode layer 20, the solid electrolyte layer 30, and the blank layers 41 and 42, may be a sintered layer formed by firing, for example. Preferably, the positive electrode layer 10, the negative electrode layer 20, the solid electrolyte layer 30, and the blank layers 41 and 42 are fired integrally with one another.

[0034] The positive electrode layer 10 and the negative electrode layer 20 may contain a conductive additive. Examples of the conductive additive that may be contained in the positive electrode layer 10 and the negative electrode layer 20 include at least one of metal materials such as silver, palladium, gold, platinum, copper, and nickel, and carbon. The conductive additive contained in the positive electrode layer 10 and the conductive additive contained in the negative electrode layer 20 may be the same or different.

[0035] Furthermore, the positive electrode layer 10 and the negative electrode layer 20 may contain a sintering aid. The sintering aid may be at least one selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, boron oxide, silicon oxide, bismuth oxide, and phosphorus oxide. The sintering aid contained in the positive electrode layer 10 and the sintering aid contained in the negative electrode layer 20 may be the same or different.

[0036] (Positive electrode layer 10) The positive electrode layer 10 is an electrode layer containing at least a positive electrode active material. In the solid state battery 101 shown in FIG. 4, the positive electrode layer 10 has a laminated structure including a positive electrode current collector 11 and a pair of positive electrode active material layers 12 and 13.

[0037] The positive electrode current collector 11 is a metal foil such as an aluminum foil. The positive electrode current collector 11 may also be a sintered body. This is to enable the solid-state battery 101 to be formed by integral firing or to reduce the internal resistance of the positive electrode current collector 11. When the positive electrode current collector 11 is a sintered body, the positive electrode current collector 11 may contain a conductive additive and a sintering additive. The conductive additive contained in the positive electrode current collector 11 may be the same as the conductive additive contained in the positive electrode active material layers 12 and 13, for example. The sintering additive contained in the positive electrode current collector 11 may be the same as the sintering additive contained in the positive electrode active material layers 12 and 13, for example. While FIG. 4 illustrates an example in which the positive electrode layer 10 includes the positive electrode current collector 11, the positive electrode current collector 11 is not an essential component. The positive electrode layer 10 may include either the positive electrode active material layer 12 or the positive electrode active material layer 13 without including the positive electrode current collector 11.

[0038] (Cathode active material layer 12, 13) The positive electrode active material layers 12 and 13 contain a positive electrode active material as a main component. The positive electrode active material layer 12 is provided on the upper surface of the positive electrode current collector 11, and the positive electrode active material layer 13 is provided on the lower surface of the positive electrode current collector 11. The positive electrode active material layers 12 and 13 can have the configuration of the solid state battery electrode 1 described in the first embodiment.

[0039] The positive electrode active material contained in the positive electrode active material layers 12, 13 is a material that participates in the absorption and release of ions in the solid-state battery 101 and in the transfer of electrons to and from the external circuit. Ions move between the positive electrode layer 10 and the negative electrode layer 20 via the solid electrolyte (i.e., ion conduction). The absorption and release of ions in the positive electrode active material is accompanied by oxidation or reduction of the positive electrode active material. Electrons or holes for such an oxidation-reduction reaction are transferred from the external circuit to the positive electrode terminal 6 or the negative electrode terminal 7, and then to the positive electrode layer 10 or the negative electrode layer 20, thereby allowing charging and discharging to proceed. The positive electrode active material layers 12, 13 contain, for example, lithium ions, sodium ions, protons (H + ), potassium ions (K + ), magnesium ions (Mg 2+ ), aluminum ions (Al 3+ ), silver ions (Ag + ), fluoride ion (F - ) or chloride ions (Cl - In other words, the solid-state battery 101 is preferably an all-solid-state secondary battery in which charging and discharging are performed by the ions moving between the positive electrode layer 10 and the negative electrode layer 20 via the solid electrolyte.

[0040] (Cathode active material) The positive electrode active material contained in the positive electrode layer 10 may be at least one selected from the group consisting of a lithium-containing phosphate compound having a Nasicon structure, a lithium-containing phosphate compound having an olivine structure, a lithium-containing layered oxide, and a lithium-containing oxide having a spinel structure. An example of a lithium-containing phosphate compound having a Nasicon structure is Li3V2(PO4)3. An example of a lithium-containing phosphate compound having an olivine structure is Li3Fe2(PO4)3, LiFePO4, LiMnPO4, LiFe 0.6 Mn 0.4 Examples of lithium-containing layered oxides include LiCoO2, LiCo 1 / 3 Ni 1 / 3 Mn 1 / 3 O2, LiCo 0.8 Ni0.15 Al 0.05 Examples of lithium-containing oxides having a spinel structure include LiMn2O4, LiNi 0.5 Mn 1.5 Examples include O4.

[0041] In addition, the positive electrode active material capable of absorbing and releasing sodium ions may be at least one selected from the group consisting of sodium-containing phosphate compounds having a Nasicon structure, sodium-containing phosphate compounds having an olivine structure, sodium-containing layered oxides, and sodium-containing oxides having a spinel structure.

[0042] (negative electrode layer 20) The negative electrode layer 20 is an electrode layer containing at least a negative electrode active material. The configuration of the solid battery electrode 1 described in the first embodiment can be adopted as the negative electrode layer 20. The negative electrode layer 20 may have a negative electrode current collector. The negative electrode current collector is, for example, a metal foil such as copper foil. The negative electrode current collector may also be a sintered body. This is to enable the solid battery 101 to be formed by integral firing or to reduce the internal resistance of the negative electrode current collector. When the negative electrode current collector is a sintered body, it may contain a conductive additive and a sintering additive.

[0043] (Negative electrode active material) The anode active material contained in the anode layer 20, like the cathode active material contained in the cathode layer 10, is a material that participates in the absorption and release of ions in the solid-state battery 101 and in the transfer of electrons to and from the external circuit. Ions move between the cathode layer 10 and the anode layer 20 via the solid electrolyte layer 30 (i.e., ion conduction). The absorption and release of ions in the anode active material is accompanied by oxidation or reduction of the anode active material. Electrons or holes for such oxidation-reduction reactions are transferred from the external circuit to the cathode terminal 6 or the anode terminal 7, and then to the cathode layer 10 or the anode layer 20, thereby allowing charging and discharging to proceed. The anode active material may contain, for example, lithium ions, sodium ions, protons (H + ), potassium ions (K +), magnesium ions (Mg 2+ ), aluminum ions (Al 3+ ), silver ions (Ag + ), fluoride ion (F - ) or chloride ions (Cl - ) can be absorbed and released. Examples of the negative electrode active material contained in the negative electrode layer 20 include at least one selected from the group consisting of an oxide containing at least one element selected from the group consisting of Ti, Si, Sn, Cr, Fe, Nb, and Mo, a graphite-lithium compound, a lithium alloy, a lithium-containing phosphate compound having a Nasicon structure, a lithium-containing phosphate compound having an olivine structure, and a lithium-containing oxide having a spinel structure. An example of a lithium alloy is Li-Al. Examples of lithium-containing phosphate compounds having a Nasicon structure are Li3V2(PO4)3 and LiTi2(PO4)3. Examples of lithium-containing phosphate compounds having an olivine structure are Li3Fe2(PO4)3 and LiCuPO4. An example of a lithium-containing oxide having a spinel structure is Li4Ti5O 12 etc.

[0044] In addition, the negative electrode active material capable of absorbing and releasing sodium ions may be at least one selected from the group consisting of sodium-containing phosphate compounds having a Nasicon structure, sodium-containing phosphate compounds having an olivine structure, and sodium-containing oxides having a spinel structure.

[0045] (Solid electrolyte layer 30) The solid electrolyte contained in the solid electrolyte layer 30 is a material capable of conducting ions such as lithium ions or sodium ions. In particular, the solid electrolyte constituting the battery constituent unit in a solid-state battery forms a layer capable of conducting, for example, lithium ions between the positive electrode layer 10 and the negative electrode layer 20. Specific examples of the solid electrolyte include lithium-containing phosphate compounds having a Nasicon structure, oxides having a perovskite structure, and oxides having a garnet or garnet-like structure. Examples of lithium-containing phosphate compounds having a Nasicon structure include Li x M y (PO4)3 (1≦x≦2, 1≦y≦2, M is at least one selected from the group consisting of Ti, Ge, Al, Ga and Zr). An example of a lithium-containing phosphate compound having a Nasicon structure is, for example, Li 1.2 Al 0.2 Ti 1.8 (PO4)3, etc. An example of an oxide having a perovskite structure is La 0.55 Li 0.35 Examples of oxides with garnet or garnet-like structures include Li7La3Zr2O 12 Examples of the solid electrolyte capable of conducting sodium ions include sodium-containing phosphate compounds having a Nasicon structure, oxides having a perovskite structure, and oxides having a garnet or garnet-like structure. Examples of the sodium-containing phosphate compounds having a Nasicon structure include Na x M y (PO4)3 (1≦x≦2, 1≦y≦2, M is at least one selected from the group consisting of Ti, Ge, Al, Ga and Zr).

[0046] Alternatively, the solid electrolyte layer 30 may be a mixture containing a first solid electrolyte 31 having a perovskite structure and a second solid electrolyte 32 having an inverse perovskite structure, as shown in FIG. 5 . FIG. 5 is a schematic cross-sectional view illustrating an example of a configuration of the solid electrolyte layer 30. By combining the first solid electrolyte 31 having a perovskite structure with the second solid electrolyte 32 having an inverse perovskite structure, a good lattice matching state can be obtained in the solid electrolyte layer 30. Specifically, the first solid electrolyte 31 is a plurality of electrolyte particles, and the second solid electrolyte 32 fills the gaps between the plurality of first solid electrolyte particles 31. In the solid electrolyte layer 30, for example, the first solid electrolyte 31 is dispersed and incorporated into the second solid electrolyte 32, and almost no grain boundaries are formed in the second solid electrolyte 32. By suppressing the formation of grain boundaries in the second solid electrolyte 32, high ionic conductivity can be obtained in the solid electrolyte layer 30, and the solid battery 101 can be rapidly charged and have a high output.

[0047] It is desirable that the lattice constant of the crystal of the first solid electrolyte 31 having a perovskite structure and the lattice constant of the crystal of the second solid electrolyte 32 having an inverse perovskite structure are similar to each other. In the perovskite structure and the inverse perovskite structure, the positively charged cations and the negatively charged anions are arranged in opposite directions. Therefore, if the lattice constants of the perovskite structure and the inverse perovskite structure are similar, the positive and negative charges will be adjacent when the two structures come into contact. Therefore, ionic bonds are formed in a lattice-matched state with little misalignment of ions, resulting in a very clean interface between the first solid electrolyte 31 and the second solid electrolyte 32. A clean interface here refers to an interface in an epitaxial state (lattice-matched state) with very few structural defects. Furthermore, the lattice-matched state refers to a state in which the ratio of the lattice constant of the anti-perovskite structure to the lattice constant of the perovskite structure is 0.9 or more and 1.1 or less. It is particularly desirable that the ratio of the lattice constant of the anti-perovskite structure to the lattice constant of the perovskite structure be 0.95 or more and 1.05 or less.

[0048] The first solid electrolyte 31 and the second solid electrolyte 32 may each have a lattice constant that is an integer multiple of, for example, 3.8 Å or more and 4.1 Å or less. Specifically, the first solid electrolyte 31 is Li 0.33 La 0.56 The second solid electrolyte 32 may be Li3OCl or Li2(OH)Cl. 0.33 La 0.56 The lattice constant of TiO3 is 3.92 Å, and the lattice constants of Li3OCl and Li2(OH)Cl are both 3.91 Å.

[0049] The solid electrolyte layer 30 may contain a sintering aid. The sintering aid that may be contained in the solid electrolyte layer 30 may be selected from, for example, the same materials as the sintering aids that may be contained in the positive electrode layer 10 and the negative electrode layer 20.

[0050] (Positive terminal 6 and negative terminal 7) The positive electrode terminal 6 and the negative electrode terminal 7 are external connection terminals for connecting the laminate 5 to an external device. The positive electrode terminal 6 and the negative electrode terminal 7 are preferably provided as end surface electrodes on the side surfaces of the laminate 5. That is, the positive electrode terminal 6 and the negative electrode terminal 7 extend along the Z-axis direction, which is the stacking direction of the laminate 5. In FIG. 4, the positive electrode terminal 6 and the negative electrode terminal 7 are arranged to face each other in the X-axis direction. As shown in FIG. 4, the positive electrode terminal 6 is electrically connected to the end surface of the positive electrode current collector 11 of the positive electrode layer 10. The negative electrode terminal 7 is electrically connected to the end surface of the negative electrode layer 20. The positive electrode terminal 6 and the negative electrode terminal 7 are preferably made of a material having high conductivity. Examples of materials for the positive electrode terminal 6 and the negative electrode terminal 7 include at least one selected from the group consisting of gold, silver, platinum, aluminum, tin, nickel, copper, manganese, cobalt, iron, titanium, and chromium. However, the constituent materials of the positive electrode terminal 6 and the negative electrode terminal 7 are not limited to those mentioned above.

[0051] (Margin layers 41, 42) The marginal layer 41 has marginal portions 411 to 413. The marginal portion 411 is in the same layer as the positive electrode current collector 11 and is provided between the positive electrode current collector 11 and the negative electrode terminal 7. The marginal portion 412 is in the same layer as the positive electrode active material layer 12 and is provided between the positive electrode active material layer 12 and the positive electrode terminal 6 and between the positive electrode active material layer 12 and the negative electrode terminal 7. The marginal portion 413 is in the same layer as the positive electrode active material layer 13 and is provided between the positive electrode active material layer 13 and the positive electrode terminal 6 and between the positive electrode active material layer 13 and the negative electrode terminal 7. The marginal layer 42 is in the same layer as the negative electrode layer 20 and is provided between the negative electrode layer 20 and the positive electrode terminal 6.

[0052] Examples of materials constituting the marginal portions 411 to 413 of the marginal layer 41 and the marginal layer 42 include materials having electronic insulation properties (hereinafter simply referred to as insulating materials).

[0053] Examples of insulating materials include glass and ceramic materials. Examples of glass materials include, but are not limited to, soda-lime glass, potash glass, borate glass, borosilicate glass, barium borosilicate glass, and zinc borate glass. lead based glasses, barium borate based glasses, bismuth borosilicate based glasses, bismuth zinc borate based glasses, bismuth silicate based glasses, phosphate based glasses, aluminophosphate based glasses, and zinc phosphate based glasses. lead The ceramic material may include, but is not limited to, at least one selected from the group consisting of aluminum oxide (Al2O3), boron nitride (BN), silicon dioxide (SiO2), silicon nitride (Si3N4), zirconium oxide (ZrO2), aluminum nitride (AlN), silicon carbide (SiC), and barium titanate (BaTiO3).

[0054] The insulating material constituting the blank layers 41, 42 may contain a solid electrolyte. In this case, the solid electrolyte contained in the insulating material is preferably the same material as the solid electrolyte contained in the solid electrolyte layer 30. This is because such a configuration can further improve the bonding between the blank layers 41, 42 and the solid electrolyte layer 30.

[0055] <2.3 Covering portion 102> 3, the covering portion 102 of the battery package 100 has a support substrate 102A, a covering insulating film 102B, and a covering inorganic film 102C. In the battery package 100, the solid-state battery 101 is entirely surrounded by the covering portion 102. In other words, the covering portion 102 is provided so that the solid-state battery 101 is not exposed to the outside.

[0056] (Support board 102A) The support substrate 102A is a plate-shaped member that supports the solid-state battery 101. The support substrate 102A has a surface 102S that faces the bottom surface 101B, which is the main surface of the solid-state battery 101. The support substrate 102A may be a resin substrate or a ceramic substrate. In a preferred embodiment, the support substrate 102A is a ceramic substrate. The support substrate 102A contains ceramic as a main component. A ceramic substrate is preferable because it has excellent water vapor prevention properties and excellent heat resistance. A ceramic substrate can be obtained, for example, by firing a green sheet laminate. Specifically, the ceramic substrate may be, for example, an LTCC (Low Temperature Co-fired Ceramics) substrate or an HTCC (High Temperature Co-fired Ceramic) substrate. By way of example only, the thickness of the support substrate 102A is 20 μm to 1000 μm, for example, 100 μm to 300 μm.

[0057] (Coating insulation film 102B) The insulating coating layer 102B is a layer provided so as to cover at least the upper surface 101A and the side surface 101C of the solid-state battery 101. As shown in FIG. 3, the solid-state battery 101 provided on the support substrate 102A is entirely surrounded by the insulating coating layer 102B. In a preferred embodiment, the insulating coating layer 102B is provided so as to cover the entire upper surface 101A and the side surface 101C of the solid-state battery 101. Of the two main surfaces constituting the solid-state battery 101, the surface positioned relatively higher is the upper surface 101A Of the two main surfaces constituting the solid-state battery 101, the surface positioned relatively lower is the bottom surface 101B. Therefore, the top surface 101A is the main surface located opposite the support substrate 102A. Therefore, the coated insulating film 102B preferably covers all surfaces of the solid-state battery 101 except for the bottom surface 101B. The coated insulating film 102B is made of, for example, a resin material capable of blocking water vapor. The coated insulating film 102B forms a suitable water vapor barrier in combination with the coated inorganic film 102C. Examples of materials used for the coated insulating film 102B include epoxy resins, silicone resins, and liquid crystal polymers. By way of example only, the thickness of the coated insulating film 102B is 30 μm or more and 1000 μm or less, and may be, for example, 50 μm or more and 300 μm or less.

[0058] (Coated inorganic film 102C) The coated inorganic film 102C is provided to cover the coated insulating film 102B. Since the coated inorganic film 102C is positioned on the coated insulating film 102B, together with the coated insulating film 102B, it has a shape that largely envelops the solid-state battery 101 on the support substrate 102A as a whole. The material of the coated inorganic film 102C is not particularly limited as long as it is an inorganic material. The coated inorganic film 102C may be metal, glass, oxide ceramic, or a mixture thereof. In a preferred embodiment, the coated inorganic film 102C contains a metal component. That is, the coated inorganic film 102C may be a metal thin film. By way of example only, the thickness of the coated inorganic film 102C is 0.1 μm or more and 100 μm or less, for example, 1 μm or more and 50 μm or less. The coated inorganic film 102C may be a dry-plated film. The dry-plated film referred to here is a film obtained by a vapor-phase method such as physical vapor deposition (PVD) or chemical vapor deposition (CVD), and is a thin film having an extremely thin thickness on the order of nanometers or micrometers. A thin dry-plated film contributes to the miniaturization and thinning of the battery package 100. The dry-plated film may contain at least one metal selected from the group consisting of aluminum (Al), nickel (Ni), palladium (Pd), silver (Ag), tin (Sn), gold (Au), copper (Cu), titanium (Ti), platinum (Pt), silicon (Si), and stainless steel. A dry-plated film made of such components is chemically and thermally stable, resulting in a solid-state battery 101 with excellent chemical resistance, weather resistance, and heat resistance, and thus improved long-term reliability.

[0059] In the battery package 100 shown in FIG. 3, the support substrate 102A is a terminal substrate provided with substrate wiring 8 including external terminals for connecting the solid-state battery 101 to an external device. The substrate wiring 8 in the support substrate 102A serving as a terminal substrate is not particularly limited as long as it allows electrical connection between the upper and lower surfaces of the support substrate 102A. In FIG. 3, the support substrate 102A is provided with substrate wiring 8 including a via 8A and a pair of lands 8B and 8C. The land 8B is exposed on the upper surface of the support substrate 102A and is electrically connected to the positive electrode terminal 6 or the negative electrode terminal 7. The land 8C is exposed on the lower surface of the support substrate 102A. The via 8A penetrates the support substrate 102A to connect the land 8B and the land 8C.

[0060] <2.4 Manufacturing method> Next, a brief description will be given of a method for manufacturing the battery package 100 of the present disclosure. The battery package 100 can be produced, for example, by a step of manufacturing the solid-state battery 101 and a step of packaging the solid-state battery 101.

[0061] (Process for manufacturing the solid-state battery 101) In manufacturing the laminate 5 of the solid-state battery 101, a printing method such as a screen printing method, a green sheet method using a green sheet, or a combination of these methods can be used.

[0062] The following description will be given using one manufacturing method as an example, but the present disclosure is not limited to the manufacturing method described below. Furthermore, the chronological order of the following descriptions is merely for the convenience of explanation, and the present disclosure is not limited to these details.

[0063] First, the positive electrode layer 10 is fabricated according to the procedure described in the first embodiment. Specifically, after preparing the positive electrode current collector 11, positive electrode active material particles, a resin, and a solvent are mixed to form a positive electrode slurry. Next, the positive electrode slurry is applied to both sides of the positive electrode current collector 11, and the applied positive electrode slurry is dried to form a positive electrode green sheet. Finally, the positive electrode green sheet is impregnated with a molten positive electrode solid electrolyte, for example, by dropping it onto the sheet. As the molten positive electrode solid electrolyte, a lithium molten salt containing at least one of Li2CO3, Li2SO4, Li3BO3, Li3OCl, and Li2OHCl may be used. In this manner, the positive electrode layer 10 is obtained.

[0064] Next, the negative electrode layer 20 is fabricated according to the procedure described in the first embodiment. Specifically, negative electrode active material particles, a resin, and a solvent are mixed to form a negative electrode slurry. Next, the negative electrode slurry is applied to a film, and the applied negative electrode slurry is dried to form a negative electrode green sheet. Finally, the negative electrode green sheet is impregnated with a molten negative electrode solid electrolyte, for example, by dropping it onto the negative electrode green sheet. As the molten negative electrode solid electrolyte, a lithium molten salt containing at least one of Li2CO3, Li2SO4, Li3BO3, Li3OCl, and Li2OHCl may be used. In this manner, the negative electrode layer 20 is obtained.

[0065] Next, the solid electrolyte sintered body is produced as follows. Specifically, first, an oxide solid electrolyte powder and an organic binder are kneaded to produce a kneaded powder. The oxide solid electrolyte powder is Li 0.33 La 0.56 TiO3 can be used. Polybutyral binder can be used as the organic binder. Next, the kneaded powder is compression molded using a method such as cold isostatic pressing (CIP) to produce a compression molded body. The compression molded body is then fired in an air atmosphere at a predetermined temperature for a predetermined time to obtain a solid electrolyte sintered body. The firing conditions are, for example, 1300°C for 10 hours.

[0066] Furthermore, an insulating material, a binder, an organic binder, a solvent, and optional additives are mixed together to prepare an insulating paste.

[0067] Next, a positive electrode layer 10, a solid electrolyte sintered body, a negative electrode layer 20, and a solid electrolyte sintered body are stacked in this order to form a laminated structure. This laminated structure corresponds to one unit U shown in FIG. 4. When fabricating this laminated structure, an insulating paste is applied to the areas where blank layers 41 and 42 will be formed. The laminated structure is impregnated with a molten solid electrolyte for the solid electrolyte layer by, for example, dropping it, and then dried. This impregnates the solid electrolyte sintered body with the solid electrolyte, resulting in a solid electrolyte layer 30. The molten solid electrolyte for the solid electrolyte layer may be a lithium molten salt containing at least one of Li2CO3, Li2SO4, Li3BO3, Li3OCl, and Li2OHCl. The dried laminated structure is compressed by cold isostatic pressing (CIP) or the like to pressure-bond the positive electrode layer 10, the solid electrolyte layer 30, the negative electrode layer 20, and the solid electrolyte layer 30. Finally, the laminate 5 is obtained by heating at a temperature of less than 800° C. in a nitrogen atmosphere.

[0068] Next, a conductive paste is applied to the side surface of the heat-treated laminate 5 where a portion of the positive electrode layer 10 is exposed, thereby forming the positive electrode terminal 6. Similarly, a conductive paste is applied to the side surface of the heat-treated laminate 5 where a portion of the negative electrode layer 20 is exposed, thereby forming the negative electrode terminal 7. The positive electrode terminal 6 and the negative electrode terminal 7 are not limited to being formed on the heat-treated laminate 5, but may be formed on the laminate structure before the heat treatment and heated simultaneously with the laminate structure.

[0069] In this way, the solid state battery 101 can be obtained.

[0070] (Process of packaging the solid-state battery 101) First, the support substrate 102A is prepared. The support substrate 102A can be obtained, for example, by stacking and firing multiple green sheets. The preparation of the support substrate 102A can be performed, for example, in accordance with the preparation of an LTCC substrate. The support substrate 102A has substrate wiring 8 formed thereon, including vias 8A and lands 8B, 8C. Specifically, for example, holes are formed in the green sheets using a punch press or a carbon dioxide laser, and the vias 8A and lands 8B, 8C are formed by filling the holes with a conductive paste material or by using a printing method. Next, a predetermined number of such green sheets are stacked and thermocompression-bonded to form a green sheet laminate, and the green sheet laminate is then fired to obtain the support substrate 102A on which the substrate wiring 8 is formed. The substrate wiring 8 can also be formed after firing the green sheet laminate.

[0071] After preparing the support substrate 102A as described above, the solid-state battery 101 is placed on the support substrate 102A. At this time, the solid-state battery 101 is placed on the support substrate 102A so that the board wiring 8 of the support substrate 102A and the positive electrode terminal 6 and negative electrode terminal 7 of the solid-state battery 101 are electrically connected to each other. Note that a conductive paste containing silver or the like may be applied onto the board wiring 8 of the support substrate 102A, and the conductive paste may be electrically connected to the positive electrode terminal 6 and negative electrode terminal 7, respectively.

[0072] Next, the insulating coating film 102B is formed so as to entirely cover the solid-state battery 101 on the support substrate 102A. When the insulating coating film 102B is made of a resin material, the resin material is applied so as to cover the side surface 101C and the top surface 101A of the solid-state battery 101, and then the resin material is cured to form the insulating coating film 102B. For example, the insulating coating film 102B may be molded by applying pressure to the resin material using a mold of a predetermined shape. Note that the molding of the insulating coating film 102B is not limited to mold molding, and may also be performed using polishing, laser processing, chemical treatment, or the like.

[0073] Next, the inorganic coated film 102C is formed so as to entirely cover the insulating coated film 102B. Specifically, for example, the inorganic coated film 102C may be formed by dry plating.

[0074] By going through the steps described above, a battery package 100 can be obtained in which the solid state battery 101 mounted on the support substrate 102A is entirely covered with the insulating coating film 102B and the inorganic coating film 102C.

[0075] <2.5 Effects> According to the battery package 100 including the solid-state battery 101 of this embodiment, the laminate 5 of the solid-state battery 101 has the positive electrode layer 10 and the negative electrode layer 20 that adopt the configuration of the solid-state battery electrode 1 described in the first embodiment. Therefore, the positive electrode layer 10 and the negative electrode layer 20 increase the area of the interface where the active material particles 2 contact the inorganic solid electrolyte 4, and can improve the conductivity of the electrode reactant (lithium ions). Therefore, the solid-state battery 101 can achieve better performance, such as being able to handle rapid charging and obtaining high output.

[0076] [3. Battery package applications] Next, uses (application examples) of the battery package including the above-described solid-state battery will be described.

[0077] The use of the battery package is not particularly limited as long as it is used mainly in machines, devices, instruments, apparatuses, and systems (assemblies of multiple devices, etc.) that can use solid-state batteries as a driving power source or a power storage source for power accumulation. The battery package used as a power source may be a main power source or an auxiliary power source. A main power source is a power source that is used preferentially regardless of the presence or absence of other power sources. An auxiliary power source may be a power source used in place of the main power source, or a power source that can be switched from the main power source as needed. When the battery package is used as an auxiliary power source, the type of main power source is not limited to one equipped with a solid-state battery.

[0078] Specific examples of uses for battery packages are as follows: Electronic devices (including portable electronic devices) such as video cameras, digital still cameras, mobile phones, notebook computers, cordless phones, headphone stereos, portable radios, portable televisions, and portable information terminals. Portable household appliances such as electric shavers. Storage devices such as backup power supplies and memory cards. Power tools such as power drills and power saws. Battery packs installed in notebook computers and the like as removable power sources. Medical electronic devices such as pacemakers and hearing aids. Electric vehicles such as electric cars (including hybrid cars). Power storage systems such as home battery systems that store power in preparation for emergencies. It is also possible to use multiple battery packages as a battery module.

[0079] The battery module is effectively applied to relatively large equipment such as electric vehicles, power storage systems, and power tools. An electric vehicle is a vehicle that operates (runs) using a battery module as a driving power source, and may be an automobile (such as a hybrid automobile) that also has a driving source other than a battery package equipped with a solid-state battery. A power storage system is a system that uses a battery package as a power storage source. In a home power storage system, a battery module is used as a power storage source. Battery package Since electricity is stored in the battery, it can be used to power household electrical appliances.

[0080] 4. Working Example An embodiment of the present disclosure will now be described.

[0081] Example 1 As described below, a solid-state battery for evaluation was fabricated, including the solid-state battery electrode (evaluation electrode) of the present disclosure shown in Figure 1, a reference electrode as its counter electrode, and a solid electrolyte layer provided between the solid-state battery electrode and the reference electrode, and then its battery characteristics were evaluated. The solid-state battery electrode had a laminated structure of a metal foil as a current collector and active material layers provided on both sides of the metal foil. The reference electrode was constructed of a laminated structure of lithium metal foil and indium metal foil.

[0082] (Fabrication of electrodes for solid-state batteries) First, a 15 μm thick copper foil was prepared as a current collector. Next, Li4Ti5O2 with a porous structure was used as an active material. 12 A composite was obtained by mixing the active material (average pore diameter: 350 nm) with a hydrophilic carboxymethyl cellulose resin (CMC) as a binder and a conductive additive containing a mixture of carbon black, acetylene black, and ketjen black. The mixture ratio of the active material, binder, and conductive additive was 90:5:5. Next, the composite was added to NMP (N-methyl-2-pyrrolidone) as an organic solvent, and the organic solvent containing the composite was stirred to prepare a paste-like slurry. The stirring was carried out for 3 minutes at a rotation speed of 2000 rpm using a hybrid mixer. Next, the slurry was applied to predetermined areas on both sides of the current collector using a coating device, and the slurry was dried to form positive electrode green sheets on both sides of the current collector.

[0083] (Preparation of reference electrode) A reference electrode was fabricated by stacking a 50 μm thick Li metal foil and a 200 μm thick In metal foil and then pressing them together at a pressure of 1 MPa. In this example, the reference electrode was positioned so that the In metal foil faced the solid-state battery electrode with the solid electrolyte layer sandwiched between them.

[0084] (Production of compression molded solid electrolyte) Li as a solid electrolyte powder 0.33 La 0.56TiO3 and Li2OHCl were mixed in a mixing ratio of 25:75 and then kneaded to produce a kneaded powder.The kneaded powder was then compression molded at a pressure of 200 MPa using the cold isostatic pressing (CIP) method to produce a compression molded body.

[0085] (Preparation of laminate) Next, the solid state battery electrodes prepared as described above and a compression-molded body of solid electrolyte were stacked together, and then heated at 270°C for 1 hour in a nitrogen atmosphere. This resulted in a positive electrode / solid electrolyte bonded sintered body. Next, the positive electrode / solid electrolyte bonded sintered body and the reference electrode were stacked, and then pressed to pressure-bond the positive electrode / solid electrolyte bonded sintered body and the reference electrode, resulting in a laminate.

[0086] Next, a conductive paste was applied to the side of the laminate where the solid-state battery electrode was partially exposed, thereby forming an electrode terminal.Similarly, a conductive paste was applied to the side of the laminate where the reference electrode was partially exposed, thereby forming a reference electrode terminal.

[0087] In this way, a solid-state battery for evaluation was obtained. 12 The median particle diameter D50 was 8 μm.

[0088] (Evaluation of battery characteristics) The battery characteristics of the solid-state battery were evaluated, and the results shown in Table 1 were obtained. Here, the cycle capacity retention rate [%] after 100 cycles in an environment at a temperature of 90°C was evaluated. Specifically, the solid-state battery of Example 1 was charged and discharged as follows. First, constant-current charging was performed at a constant current of 0.5 mA until the battery voltage reached the specified charge voltage shown in Table 1, and constant-voltage charging was performed until the specified charge voltage reached 0.05 mA. Subsequently, constant-current discharging was performed at a constant current of 0.5 mA until the specified discharge voltage was reached. This combination of charging and discharging constituted one cycle, and this was repeated 100 times. The ratio of the discharge capacity at the 100th cycle to the discharge capacity at the first cycle was calculated, and this value was taken as the cycle capacity retention rate [%] after 100 cycles.

[0089] <Example 2> As shown in Table 1, a solid state battery for evaluation was fabricated in the same manner as in Example 1, except that an aluminum foil having a thickness of 15 μm was used as the current collector of the electrode for the solid state battery, and lithium nickel cobalt aluminum oxide (NCA (average pore diameter of 30 nm)) having a porous structure was used as the active material, and then the battery characteristics were evaluated in the same manner as in Example 1. The results are also shown in Table 1. The median diameter D50 of the particles of the porous NCA used as the active material was 18 μm.

[0090] <Comparative Example 1> Except for using hydrophobic PVDF (polyvinylidene fluoride) as the binder for the solid state battery electrodes, a solid state battery for evaluation was fabricated in the same manner as in Example 1, and then the battery characteristics were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

[0091] <Comparative example 2 > As a solid electrolyte, Li7La3Zr2O, which has a melting point of 1550°C, 12 A solid-state battery for evaluation was fabricated in the same manner as in Example 1, except that a porous Li4Ti5O2 was used as the active material, and hydrophobic PVDF (polyvinylidene fluoride) was used as the binder for the solid-state battery electrodes. The battery characteristics were then evaluated in the same manner as in Example 1. The results are also shown in Table 1. 12 The median particle diameter D50 was 3.91 μm.

[0092] [Table 1]

[0093] [Consideration] As shown in Table 1, Examples 1 and 2 exhibited significantly lower porosities and higher cycle capacity retention rates after 100 cycles than Comparative Examples 1 and 2. This indicates that even when the surface area of active material particles is increased by employing active material particles with a porous structure, the increase in resistance associated with repeated charge and discharge can be suppressed. Generally, when a liquid electrolyte is used, increasing the surface area of the active material particles increases the resistance as the number of cycles increases. In contrast, in Examples 1 and 2, the use of a hydrophilic binder allows the inorganic solid electrolyte to sufficiently impregnate the pores of the active material particles, forming a favorable interface between the active material particles and the inorganic solid electrolyte. As a result, the area of the interface with which lithium, the electrode reactant, reacts can be increased, thereby improving the ionic conductivity of lithium ions in the positive electrode.

[0094] The present disclosure has been described above with reference to several embodiments, modifications, and examples, but the configuration of the present disclosure is not limited to the configuration described above and can be modified in various ways.

[0095] Specifically, for example, in the first embodiment, the battery package 100 is described in which the solid-state battery 101 is placed on the support substrate 102A and packaged, but the battery package of the present disclosure is not limited to this form. For example, the battery package may not have a support substrate and may be sealed only by a covering insulating film or a covering inorganic film.

[0096] Furthermore, in the first embodiment, the electrode reactant is lithium, but the electrode reactant is not particularly limited. Therefore, as described above, the electrode reactant may be other alkali metals such as sodium and potassium, or alkaline earth metals such as beryllium, magnesium, and calcium. In addition, the electrode reactant may be other light metals such as aluminum.

[0097] The effects described in this specification are merely examples, and the effects of the present disclosure are not limited to the effects described in this specification. Therefore, other effects may be obtained with respect to the present disclosure.

Claims

1. a plurality of active material particles each having a porous structure including voids therein; a binder, which is a hydrophilic organic compound, provided in gaps between the plurality of active material particles; an inorganic solid electrolyte that is soluble at a temperature lower than the volatilization temperature of the binder and is impregnated into the pores; An electrode for a solid-state battery comprising:

2. The inorganic solid electrolyte is also provided in the gaps between the plurality of active material particles. The electrode for a solid state battery according to claim 1 .

3. The inorganic solid electrolyte can be melted at a temperature of 200° C. or higher and 400° C. or lower. The electrode for a solid state battery according to claim 1 or 2.

4. The binder is an organic compound having a functional group containing OH at the end. The electrode for a solid state battery according to claim 1 or 2.

5. The binder is a polyacrylic resin, a polyvinyl alcohol resin, a cellulose resin, or a phenol resin. The electrode for a solid state battery according to claim 4.

6. The binder is an acrylamide resin, an ester resin, an epoxy resin, or a melamine resin. The electrode for a solid state battery according to claim 1 or 2.

7. The size of the pores is 10 nm or more and 500 nm or less. The electrode for a solid state battery according to claim 1 or 2.

8. The median diameter D50 of the active material particles is 3 μm or more and 30 μm or less. The electrode for a solid state battery according to claim 1 or 2.

9. The weight ratio of the binder to the total weight excluding the inorganic solid electrolyte is 3% or less. The electrode for a solid state battery according to claim 1 or 2.

10. In any cross section, the porosity, which is the ratio of the total area occupied by voids to the total area, is less than 5%. The electrode for a solid state battery according to claim 1 or 2.

11. The inorganic solid electrolyte is Li ２ CO ３ , Li ２ SO ４ , Li ３ BO ３ , Li ３ OCl, Li ２ OHCl, Li ３ OF, Li ３ OBr, Li ３ OI, Li ２ OHF, Li ２ OHBr, and Li ２ It is a lithium salt containing at least one of The electrode for a solid state battery according to claim 1 or 2.

12. forming a slurry by mixing active material particles having a porous structure including voids therein, a binder which is a hydrophilic organic compound, and a solvent; applying the slurry onto a film and then drying the applied slurry to form a green sheet; impregnating the green sheet with an inorganic solid electrolyte dissolved at a temperature below the volatilization temperature of the binder; Contains A method for manufacturing electrodes for solid-state batteries.

13. A positive electrode and a negative electrode; a solid electrolyte layer interposed between the positive electrode and the negative electrode; Equipped with At least one of the positive electrode and the negative electrode is a plurality of active material particles each having a porous structure including voids therein; a binder, which is a hydrophilic organic compound, provided in gaps between the plurality of active material particles; an inorganic solid electrolyte that is soluble at a temperature lower than the volatilization temperature of the binder and is impregnated into the pores; have solid state battery.

14. The inorganic solid electrolyte is also provided in the gaps between the plurality of active material particles. The solid-state battery according to claim 13.

15. The binder is an organic compound having a functional group containing OH at the end. The solid-state battery according to claim 13 or 14.

16. The solid electrolyte layer is a first solid electrolyte having a perovskite structure with a lattice constant that is an integer multiple of 3.8 Å or more and 4.1 Å or less; a second solid electrolyte having an antiperovskite structure with a lattice constant that is an integer multiple of 3.8 Å or more and 4.1 Å or less; have The solid state battery according to claim 13 or 14.

17. the first solid electrolyte has a plurality of electrolyte particles; The second solid electrolyte is provided between the plurality of electrolyte particles. The solid-state battery according to claim 16.

18. The first solid electrolyte is Li ０．３３ La ０．５６ TiO ３ and The second solid electrolyte is Li ３ OCl The solid-state battery according to claim 16.

19. A solid-state battery; a covering portion that covers the solid-state battery; Equipped with The solid-state battery comprises: A positive electrode and a negative electrode; a solid electrolyte layer interposed between the positive electrode and the negative electrode; Equipped with At least one of the positive electrode and the negative electrode is a plurality of active material particles each having a porous structure including voids therein; a binder, which is a hydrophilic organic compound, provided in gaps between the plurality of active material particles; an inorganic solid electrolyte that is soluble at a temperature lower than the volatilization temperature of the binder and is impregnated into the pores; have Battery package.

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