Sintered electrode, battery member, and method for manufacturing sintered electrode and battery member

Abstract

Provided are a sintered body electrode, a battery member, and sintered body electrode and battery member manufacturing methods, with which it is possible to improve safety and also to operate batteries at a low temperature.　A sintered body electrode 3 according to the present invention is characterized by comprising: an alkali ion conductive solid electrolyte; and a carbon electrode material composed of graphite or hard carbon.

Description

[Technical Field]

[0001] The present invention relates to a sintered electrode and a battery member using the same, a method for manufacturing a sintered electrode and a battery member, an alkali ion-conductive solid electrolyte precursor solution, an alkali ion-conductive solid electrolyte precursor, and an alkali ion-conductive solid electrolyte. [Background technology]

[0002] Lithium-ion secondary batteries have established themselves as high-capacity, lightweight power sources essential for mobile devices, electric vehicles, and other applications. However, current lithium-ion secondary batteries primarily use flammable organic electrolytes, raising concerns about the risk of fire. To address this issue, development of all-solid-state lithium-ion batteries, which use solid electrolytes instead of organic electrolytes, is underway. However, due to concerns about the rising cost of lithium raw materials worldwide, research into all-solid-state sodium-ion batteries as an alternative has been underway in recent years.

[0003] Patent Document 1 below discloses an example of a sodium battery. This sodium battery has a positive electrode, a negative electrode, and a sulfide-based solid electrolyte. The positive electrode uses a metal sulfide or a sodium metal oxide. The negative electrode uses sodium metal or a sodium alloy. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-208324 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in a sodium battery such as that described in Patent Document 1, it is difficult to sufficiently improve safety because the sodium metal used in the negative electrode is prone to react with moisture.

[0006] Furthermore, conventional all-solid-state sodium batteries often operate at relatively high temperatures, such as 60° C. or higher, and have the problem of being difficult to operate satisfactorily at low temperatures.

[0007] An object of the present invention is to provide a sintered electrode, a battery member, a method for manufacturing a sintered electrode and a battery member, a solid electrolyte precursor solution, a solid electrolyte precursor, and a solid electrolyte, which can improve safety and enable a battery to operate at low temperatures. [Means for solving the problem]

[0008] The sintered electrode according to the present invention is characterized by comprising a carbon electrode material made of graphite or hard carbon, and an alkali ion conductive solid electrolyte.

[0009] The alkali ion conductive solid electrolyte preferably has sodium ion conductivity.

[0010] The alkali ion conductive solid electrolyte preferably comprises an oxide.

[0011] The sintered electrode according to the present invention preferably contains a mixed phase of a carbon electrode material and an alkali ion conductive solid electrolyte, the mixed phase being made up of particles, the particles preferably having an average particle size of 10 μm or less.

[0012] It is preferred that the carbon electrode material is a particulate carbon electrode material, and that the particulate carbon electrode material is covered with a coating layer made of an alkali ion conductive solid electrolyte.

[0013] It is preferred that the carbon electrode material is a particulate carbon electrode material, and that the particulate carbon electrode material is covered with a coating layer made of a carbon electrode material other than the particulate carbon electrode material and an alkali ion conductive solid electrolyte.

[0014] The alkali ion conductive solid electrolyte is a NASICON type crystal and has the general formula Na1+x Zr2P 3-x Si x O 12 It is preferable to include at least one compound selected from the first compound represented by (0 ≦ x ≦ 3) and the second compound in which a part of Zr of the first compound is substituted with at least one element selected from the group consisting of Ca, Mg, Ba, Sr, Al, Nb, Ta, In, Ga, and group 3 elements.

[0015] It is preferable that the alkali ion conductive solid electrolyte has at least one of β-alumina type crystal and β”-alumina type crystal.

[0016] The alkali ion conductive solid electrolyte has the general formula Li7La3Zr2O 12 , Li7La3Zr 2-x M x O 12 (M is at least one selected from Nb, Ga, and Ta, 0 < x < 2), or Li 7-3x Al x La3Zr2O 12 It is preferable to have a crystal phase represented by (0 < x < 2.3).

[0017] The sintered body electrode according to the present invention preferably contains 0 wt% to 20 wt% of at least one carbon-based conductive aid selected from carbon black, acetylene black, ketjen black, carbon nanotubes, and vapor-grown carbon fiber (VGCF).

[0018] The sintered body electrode according to the present invention is preferably a negative electrode.

[0019] It is preferable that the sintered body electrode according to the present invention can occlude and release alkali ions at 30°C after heat treatment in an inert atmosphere at 500°C.

[0020] It is preferable that the sintered body electrode according to the present invention can be reversibly charged and discharged with a charge-discharge efficiency of 90% or more when charged and discharged at a cut-off voltage of 9V to 0.001V.

[0021] A battery member according to the present invention is characterized by comprising a solid electrolyte layer and the above-mentioned sintered electrode laminated on the solid electrolyte layer.

[0022] The thickness of the solid electrolyte layer is preferably 5 nm to 1 mm.

[0023] A battery according to the present invention is characterized by including the battery member described above.

[0024] The method for producing a sintered electrode according to the present invention is characterized by comprising: a mixing step of obtaining a mixture of an alkali ion conductive solid electrolyte precursor and a carbon electrode material precursor by mixing an alkali ion conductive solid electrolyte precursor with a carbon electrode material precursor, wherein the carbon electrode material precursor is a precursor of a carbon electrode material made of graphite or hard carbon; a step of forming an electrode-forming material layer containing the mixture after the mixing step; and a step of firing the electrode-forming material layer.

[0025] It is preferred that the electrode-forming material layer is made of a paste or a compact containing an alkali ion-conductive solid electrolyte precursor and a carbon electrode material precursor, and that the alkali ion-conductive solid electrolyte and the carbon electrode material are obtained simultaneously in the step of firing the electrode-forming material layer.

[0026] In the step of forming an electrode-forming material layer, it is preferable that after a first firing step is performed in which a carbon electrode material is obtained by firing the mixture, an electrode-forming material layer made of a paste or a compact containing an alkali ion-conductive solid electrolyte precursor and the carbon electrode material is formed, and an alkali ion-conductive solid electrolyte is obtained from the alkali ion-conductive solid electrolyte precursor in the step of firing the electrode-forming material layer.

[0027] It is preferable that the method further comprises a third firing step after the mixing step, in which the mixture is fired to simultaneously obtain the alkali ion conductive solid electrolyte and the carbon electrode material, and that in the step of forming an electrode-forming material layer, the electrode-forming material layer is formed from a paste or a compact containing the alkali ion conductive solid electrolyte and the carbon electrode material.

[0028] In another aspect of the present invention, a method for producing a sintered electrode comprises the steps of: a mixing step of mixing an alkali ion-conductive solid electrolyte precursor with a particulate carbon electrode material made of graphite or hard carbon to obtain a mixture of the alkali ion-conductive solid electrolyte precursor and the particulate carbon electrode material; a step of forming, after the mixing step, an electrode-forming material layer made of a paste or a compact containing the alkali ion-conductive solid electrolyte precursor and the particulate carbon electrode material; and a step of firing the electrode-forming material layer to obtain an alkali ion-conductive solid electrolyte from the alkali ion-conductive solid electrolyte precursor, thereby obtaining a particulate carbon electrode material covered with a coating layer made of the alkali ion-conductive solid electrolyte.

[0029] In yet another aspect of the present invention, a method for producing a sintered electrode includes the steps of: mixing an alkali ion-conductive solid electrolyte precursor, a carbon electrode material precursor, and a particulate carbon electrode material made of graphite or hard carbon to obtain a mixture of an alkali ion-conductive solid electrolyte precursor, a carbon electrode material precursor, and a particulate carbon electrode material, wherein the carbon electrode material precursor is a precursor of a carbon electrode material made of graphite or hard carbon; forming, after the mixing step, an electrode-forming material layer made of a paste or a compact containing the mixture; and firing the electrode-forming material layer to obtain an alkali ion-conductive solid electrolyte and a carbon electrode material from the alkali ion-conductive solid electrolyte precursor and the carbon electrode material precursor, thereby obtaining a particulate carbon electrode material covered with a coating layer made of the alkali ion-conductive solid electrolyte and the carbon electrode material.

[0030] The method for producing a battery member of the present invention is a method for producing a battery member including a laminate of a sintered electrode and a solid electrolyte layer, and is characterized by comprising the following steps: a mixing step of mixing an alkali ion conductive solid electrolyte precursor with a carbon electrode material precursor to obtain a mixture of the alkali ion conductive solid electrolyte precursor and the carbon electrode material precursor, where the carbon electrode material precursor is a precursor of a carbon electrode material made of graphite or hard carbon; a step of forming an electrode-forming material layer including the mixture after the mixing step; a step of firing the electrode-forming material layer to obtain a sintered electrode; and a step of obtaining a laminate of the sintered electrode and the solid electrolyte layer.

[0031] It is preferred that the electrode-forming material layer is made of a paste or a compact containing an alkali ion-conductive solid electrolyte precursor and a carbon electrode material precursor, and that the alkali ion-conductive solid electrolyte and the carbon electrode material are simultaneously obtained by firing the electrode-forming material layer.

[0032] In the step of forming an electrode-forming material layer, after a first firing step in which a carbon electrode material is obtained by firing a mixture is performed, the step of forming an electrode-forming material layer made of a paste or a compact containing an alkali ion conductive solid electrolyte precursor and a carbon electrode material to obtain a sintered electrode is preferably a second firing step in which an alkali ion conductive solid electrolyte is obtained by firing the electrode-forming material layer.

[0033] Preferably, the method further comprises a third firing step after the mixing step, in which the mixture is fired to simultaneously obtain the alkali ion conductive solid electrolyte and the carbon electrode material, and in the step of forming an electrode-forming material layer, an electrode-forming material layer made of a paste or a compact containing the alkali ion conductive solid electrolyte and the carbon electrode material is formed, and the step of obtaining a sintered electrode is a fourth firing step in which the electrode-forming material layer is fired.

[0034] In another aspect of the present invention, there is provided a method for producing a battery member including a laminate of a sintered electrode and a solid electrolyte layer, the method comprising the steps of: a mixing step of mixing an alkali ion-conductive solid electrolyte precursor with a particulate carbon electrode material made of graphite or hard carbon to obtain a mixture of the alkali ion-conductive solid electrolyte precursor and the particulate carbon electrode material; a step of forming, after the mixing step, an electrode-forming material layer made of a paste or a compact containing the alkali ion-conductive solid electrolyte precursor and the particulate carbon electrode material; a step of firing the electrode-forming material layer to obtain an alkali ion-conductive solid electrolyte from the alkali ion-conductive solid electrolyte precursor and to obtain the particulate carbon electrode material covered with a coating layer made of the alkali ion-conductive solid electrolyte, thereby obtaining a sintered electrode; and a step of obtaining a laminate of the sintered electrode and the solid electrolyte layer.

[0035] It is preferable that the method further comprises a lamination step of laminating the solid electrolyte layer and the electrode-forming material layer, and that a step of obtaining a sintered electrode is carried out after the lamination step.

[0036] It is preferable that the method further includes a lamination step of laminating a solid-electrolyte-forming material layer made of a paste or a compact containing a solid electrolyte precursor and an electrode-forming material layer, and that after the lamination step, the electrode-forming material layer and the solid-electrolyte-forming material layer are fired to simultaneously obtain a sintered electrode and a solid electrolyte layer.

[0037] The alkali ion conductive solid electrolyte precursor solution according to the present invention is characterized by containing an alkali metal element, a transition metal element, and carbonate ions.

[0038] It is preferred that the carbonate ion is coordinated to the transition metal element.

[0039] The transition metal element is preferably at least one selected from the group consisting of Group 3 elements and Group 4 elements.

[0040] The alkali ion conductive solid electrolyte precursor solution according to the present invention preferably has a pH of 7 or higher.

[0041] As a counter ion of carbonate ion, NR4 + (wherein each R is independently at least one substituent selected from the group consisting of H, CH3, C2H5 and CH2CH2OH).

[0042] The alkali ion conductive solid electrolyte precursor solution according to the present invention is preferably a precursor solution for a solid electrolyte made of NASICON-type crystals.

[0043] The alkali ion conductive solid electrolyte precursor solution according to the present invention is preferably a precursor solution for a sodium ion conductive solid electrolyte.

[0044] The alkali ion conductive solid electrolyte precursor according to the present invention is characterized in that it comprises a gel or dried product of the alkali ion conductive solid electrolyte precursor solution described above.

[0045] The alkali ion conductive solid electrolyte according to the present invention is characterized by comprising a calcined product of the alkali ion conductive solid electrolyte precursor. [Effects of the Invention]

[0046] According to the present invention, it is possible to provide a sintered electrode, a battery member, a method for manufacturing a sintered electrode and a battery member, a solid electrolyte precursor solution, a solid electrolyte precursor, and a solid electrolyte, which can improve safety and enable a battery to operate at low temperatures. [Brief explanation of the drawings]

[0047] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a battery member according to a first embodiment of the present invention. [Figure 2] FIG. 2 is an SEM image showing a sintered electrode according to one embodiment of the present invention. [Figure 3]3(a) and 3(b) are schematic cross-sectional views illustrating the method for manufacturing a battery member according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing the results of the charge-discharge test of the comparative example. [Figure 5] FIG. 5 is a diagram showing the results of a charge-discharge test of Example 1 of the present invention. [Figure 6] FIG. 6 is a diagram showing the results of a charge / discharge test performed on the test battery prepared in Example 1 of the present invention when the test battery was charged and discharged at a cutoff voltage of 9V to 0.001V. [Figure 7] FIG. 7 shows XRD (X-ray diffraction) charts of the alkali ion conductive solid electrolyte precursors prepared in Example 2 and Reference Example of the present invention after drying and after firing. [Figure 8] 8(a) and 8(b) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to a second embodiment of the present invention. [Figure 9] 9(a) and 9(b) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to a third embodiment of the present invention. [Figure 10] 10(a) and 10(b) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to a fourth embodiment of the present invention. [Figure 11] 11(a) to 11(c) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to Modification 1 of the fourth embodiment of the present invention. [Figure 12] 12(a) to 12(c) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to Modification 2 of the fourth embodiment of the present invention. [Figure 13] 13(a) and 13(b) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to a fifth embodiment of the present invention. [Figure 14] 14(a) and 14(b) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to a sixth embodiment of the present invention. [Figure 15]15(a) and 15(b) are schematic cross-sectional views illustrating a method for manufacturing a sintered electrode according to a seventh embodiment of the present invention. [Figure 16] 16(a) and 16(b) are schematic cross-sectional views illustrating a method for manufacturing a sintered electrode according to an eighth embodiment of the present invention. [Figure 17] 17(a) and 17(b) are schematic cross-sectional views illustrating a method for manufacturing a sintered electrode according to a ninth embodiment of the present invention. [Figure 18] FIG. 18 is a schematic cross-sectional view showing a battery member according to the second embodiment of the present invention. [Figure 19] 19(a) and 19(b) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to a tenth embodiment of the present invention. [Figure 20] 20(a) and 20(b) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to an eleventh embodiment of the present invention. [Figure 21] 21(a) and 21(b) are schematic cross-sectional views illustrating a method for manufacturing a sintered electrode according to a twelfth embodiment of the present invention. [Figure 22] FIG. 22 is a schematic cross-sectional view showing a battery member according to a third embodiment of the present invention. [Figure 23] 23(a) and 23(b) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to a thirteenth embodiment of the present invention. [Figure 24] FIG. 24 is a diagram showing the results of a charge-discharge test of Example 3 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0048] Preferred embodiments will be described below. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. In addition, in the drawings, components having substantially the same functions may be referred to by the same reference numerals.

[0049] [Battery materials] (First embodiment) Fig. 1 is a schematic cross-sectional view showing a battery member according to a first embodiment of the present invention. Fig. 1 is a schematic cross-sectional view of the member as seen from the side. The same applies to the following schematic cross-sectional views other than Fig. 1.

[0050] The battery component 1 includes a solid electrolyte layer 2, a sintered electrode 3 according to one embodiment of the present invention, and a current collector 4. The solid electrolyte layer 2 has alkali ion conductivity. More specifically, in this embodiment, the solid electrolyte layer 2 has sodium ion conductivity. However, the solid electrolyte layer 2 may also have lithium ion conductivity. The solid electrolyte layer 2 is preferably as thin as possible to increase the energy density, and specifically, the thickness is preferably 1 mm or less, more preferably 500 μm or less, and even more preferably 100 μm or less. There is no particular lower limit, but in reality, a thickness of 5 nm or more is preferable to ensure mechanical strength and separator function.

[0051] The solid electrolyte layer 2 has a first main surface 2a and a second main surface 2b. The first main surface 2a and the second main surface 2b face each other. A sintered electrode 3 is laminated on the first main surface 2a of the solid electrolyte layer 2. A current collector 4 is laminated on the sintered electrode 3. The current collector 4 is made of an appropriate metal thin film. The battery member 1 does not necessarily have to have the current collector 4. In the embodiments described below, the current collector 4 may be omitted from the illustration.

[0052] In this embodiment, the sintered electrode 3 is a negative electrode. By laminating a positive electrode on the second main surface 2b of the solid electrolyte layer 2, an all-solid-state battery can be obtained.

[0053] The sintered electrode 3 includes a carbon electrode material and an alkali ion conductive solid electrolyte. The carbon electrode material is made of graphite or hard carbon. In this embodiment, the alkali ion conductive solid electrolyte has sodium ion conductivity. However, the alkali ion conductive solid electrolyte may also have lithium ion conductivity.

[0054] The sintered electrode 3 includes a mixed phase 5 of a carbon electrode material and an alkali ion conductive solid electrolyte. The mixed phase 5 is in the form of particles. The particles of the mixed phase 5 are bonded together by sintering.

[0055] FIG. 2 is an SEM image showing a sintered electrode according to one embodiment of the present invention. In FIG. 2, it can be seen that particles are bonded together. These particles form a mixed phase 5. It can be seen that in the mixed phase 5, the boundary between the carbon electrode material and the alkali ion conductive solid electrolyte is indistinguishable. Thus, in the mixed phase 5, the carbon electrode material and the alkali ion conductive solid electrolyte are uniformly mixed. The average particle size of each particle constituting the mixed phase 5 is preferably 10 μm or less, more preferably 3 μm or less, even more preferably 500 nm or less, and particularly preferably 300 nm or less. This can increase the density of the sintered electrode 3.

[0056] Returning to FIG. 1, the sintered electrode 3 preferably contains a conductive additive 6. By including the conductive additive 6, a conductive path is formed, thereby reducing the internal resistance of the sintered electrode 3. If too much conductive additive 6 is added, the amount of shrinkage increases during drying and sintering of the paste, making it difficult to form the electrode. Therefore, the amount added is preferably 0 to 20% by weight, and more preferably 0.1 to 10% by weight. However, the sintered electrode 3 does not necessarily need to contain the conductive additive 6. The sintered electrode 3 does not contain a binder (organic binder).

[0057] The battery member 1 includes a sintered electrode 3 of the present invention, which includes a carbon electrode material made of graphite or hard carbon and an alkali ion conductive solid electrolyte. Unlike electrodes made of sodium metal, the sintered electrode 3 has low reactivity to moisture. Furthermore, since it can be used in all-solid-state batteries and does not require an organic electrolyte, the risk of fire is further reduced. This improves safety. Furthermore, the use of the battery member 1 enables batteries to be operated at low temperatures. Details of this effect will be described below with reference to a manufacturing method according to a first embodiment of the present invention and examples using the same. Note that, in this specification, battery members and manufacturing methods according to embodiments of the present invention will be described with separate serial numbers. Specifically, battery members according to first to third embodiments of the present invention and methods for manufacturing battery members or sintered electrodes according to first to thirteenth embodiments of the present invention will be described below.

[0058] [Manufacturing method] (First embodiment) 3(a) and 3(b) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to the first embodiment. First, an electrode paste 13A and a solid electrolyte layer 2 shown in FIG. 3(a) are prepared. The paste 13A is the electrode-forming material layer of the present invention. In this specification, the electrode-forming material layer refers to a material layer for obtaining (forming) a sintered electrode by firing. The electrode-forming material layer may be made of, for example, a paste as in this embodiment, or may be made of a compacted powder.

[0059] To obtain the paste 13A, an alkali ion conductive solid electrolyte precursor is prepared. At this stage, it is preferable to prepare an alkali ion conductive solid electrolyte precursor solution. Specific examples of the alkali ion conductive solid electrolyte precursor and its solution will be described later. Furthermore, a carbon electrode material precursor (a precursor of a carbon electrode material made of graphite or hard carbon) is prepared. The carbon electrode material precursor may be made of an appropriate sugar, biomass, polymer, or the like.

[0060] Next, the alkali ion conductive solid electrolyte precursor solution and the carbon electrode material precursor are mixed and then dried. This results in a mixture of the alkali ion conductive solid electrolyte precursor and the carbon electrode material precursor. Next, the mixture is pulverized to obtain a powder, which is then mixed with the conductive additive 6 and a binder in an organic solvent. The organic solvent may be, for example, N-methylpyrrolidone. This results in a paste 13A.

[0061] On the other hand, the solid electrolyte layer 2 can be obtained by mixing raw material powders, molding the mixed raw material powders, and then firing the molded product. For example, the raw material powders are slurried to form a green sheet, and the green sheet is then fired to obtain the solid electrolyte layer 2. The solid electrolyte layer 2 may also be obtained by a sol-gel method.

[0062] Next, as shown in FIG. 3(a), paste 13A is applied to the first main surface 2a of the solid electrolyte layer 2. In this manner, a lamination step is performed in which the solid electrolyte layer 2 and the paste 13A as an electrode-forming material layer are laminated. Next, the laminate of the solid electrolyte layer 2 and the paste 13A is fired in an N2 atmosphere at a temperature above 500°C and not higher than 1300°C (preferably above 800°C and not higher than 1150°C). The firing may be performed in an inert atmosphere. For example, the firing may be performed in an Ar, Ne, or He atmosphere, or in a vacuum. The firing steps in other embodiments are similar.

[0063] This simultaneously produces an alkali ion-conductive solid electrolyte and a carbon electrode material, resulting in a mixed phase 5 of the alkali ion-conductive solid electrolyte and the carbon electrode material. In this way, as shown in FIG. 3(b), a sintered electrode 3 is obtained, resulting in a laminate of the sintered electrode 3 and the solid electrolyte layer 2. If the firing temperature is too low, the reaction will be insufficient, making it difficult to obtain the desired sintered electrode 3. As a result, the internal resistance of the sintered electrode 3 tends to increase, and the charge / discharge efficiency tends to decrease. On the other hand, if the firing temperature is too high, the alkali component may evaporate from the alkali ion-conductive solid electrolyte precursor, making it difficult to obtain an alkali ion-conductive solid electrolyte having the desired composition. As a result, the internal resistance of the sintered electrode 3 tends to increase, and the charge / discharge efficiency tends to decrease.

[0064] Next, a current collector 4 is formed on the sintered electrode 3. The method for forming the current collector 4 is not particularly limited, and examples thereof include physical vapor deposition methods such as vapor deposition or sputtering, and chemical vapor deposition methods such as thermal CVD, MOCVD, and plasma CVD. However, it is not always necessary to form the current collector 4.

[0065] In this manner, the battery member 1 can be obtained. Note that the binder is decomposed by the firing. Therefore, the sintered electrode 3 in the battery member 1 does not contain a binder. Here, specific examples of materials for each component of the battery member 1 will be described.

[0066] Carbon electrode material precursors; When sugars are used as the carbon electrode material precursor, examples include sucrose, cellulose, D-glucose, and sucrose. When biomass is used as the carbon electrode material precursor, examples include corn stalks, sorghum stalks, pine cones, mangosteen, argan shells, rice husks, dandelions, cereal straw cores, ramie fiber, cotton, kelp, and coconut endocarp. When polymers are used as the carbon electrode material precursor, examples include polyacrylonitrile (PAN), pitch, polyvinyl chloride (PVC) nanofibers, polyaniline, sodium polyacrylate, tires (tire polymers), and phosphorus-doped PAN.

[0067] Alkali ion conducting solid electrolyte in sintered electrode 3; The alkali ion conductive solid electrolyte is preferably made of an oxide. An alkali ion conductive solid electrolyte made of an oxide is stable against the atmosphere, and therefore can improve the safety of the battery. In general, alkali ion conductive solid electrolytes made of oxides are hard materials with a high Young's modulus and do not easily soften or flow by heat treatment, making it difficult to densify them by cold pressing or sintering. However, the manufacturing method of this embodiment makes it possible to obtain a dense sintered body.

[0068] Examples of alkali ion conductive solid electrolytes include beta-alumina crystals and NASICON crystals, which have excellent sodium ion conductivity. Beta-alumina has two crystal types: β-alumina (theoretical composition: Na2O·11Al2O3) and β"-alumina (theoretical composition: Na2O·5.3Al2O3). β"-alumina is a metastable substance, so it is usually used with Li2O or MgO added as a stabilizer. β"-alumina has higher sodium ion conductivity than β-alumina, so it is preferable to use β"-alumina alone or a mixture of β"-alumina and β-alumina, and Li2O-stabilized β"-alumina (Na 1.7 Li 0.3 Al 10.7 O 17 ) or MgO-stabilized β”-alumina ((Al 10.32 Mg 0.68 O 16 )(Na 1.68 It is more preferable to use O).

[0069] NASICON type crystals include those of the general formula Na 1+x X2P 3-x Si x O 12 (X is at least one transition metal element selected from the group 4 elements, and 0≦x≦3). In particular, it is preferable to include at least one compound selected from the following first and second compounds. The first compound is represented by the general formula Na1+x Zr2P 3-x Si x O 12 (0≦x≦3). The second compound is a compound in which part of the Zr in the first compound is substituted with at least one element selected from the group consisting of Ca, Mg, Ba, Sr, Al, Nb, Ta, In, Ga, and Group 3 elements. The Group 3 element may be at least one element selected from the group consisting of Sc, Y, and La.

[0070] Examples of the first compound and the second compound include Na3Zr2Si2PO 12 , Na3Zr 1.6 Ti 0.4 SiPO 12 , Na3Zr 1.88 Y 0.12 SiPO 12 Other examples of NASICON type crystals include Na 3.2 Zr 1.3 Si 2.2 P 0.7 O 10.5 , Na3Hf2Si2PO 12 , Na 3.4 Zr 0.9 Hf 1.4 Al 0.6 Si 1.2 P 1.8 O 12 , Na3Zr 1.7 Nb 0.24 SiPO 12 , Na 3.6 Ti 0.2 Y 0.7 Si 2.8 O9, Na 3.12 Zr 1.88 Y 0.12 SiPO 12 , Na 3.6 Zr 0.13 Yb 1.67 Si 0.11 P 2.9 O 12 , Na 3.12 Zr 1.88 Y 0.12 SiPO 12 The following can be mentioned:

[0071] As the alkali ion conductive solid electrolyte, in addition to the above, there is also a crystal phase represented by the general formula Na5XSi4O 12 . X is at least one selected from Group 3 transition metal elements, specifically rare earth elements. Examples of rare earth elements include, in addition to Dy, Gd, Y, and Sm, Sc, La, Ce, Pr, Nd, Pm, Eu, Tb, Ho, Er, Tm, Yb, and Lu. Preferably, Pr, Nd, Sm, Gd, Dy, or Y is used, and more preferably, Y, Sm, Dy, or Gd is used. Also, part of Si may be substituted with P.

[0072] As the alkali ion conductive solid electrolyte, there may also be a crystal phase represented by the general formula Li7La3Zr2O 12 , Li7La3Zr 2-x M x O 12 (M is at least one selected from Nb, Ga, and Ta, 0 < x < 2), or Li 7-3x Al x La3Zr2O 12 (0 < x < 2.3).

[0073] Alkali ion conductive solid electrolyte precursor and its solution; When the alkali ion conductive solid electrolyte is beta-alumina, the alkali ion conductive solid electrolyte precursor can be obtained, for example, by mixing aluminum nitrate, sodium nitrate, and lithium nitrate. At this time, the ratio of each of the above materials is adjusted to be the composition ratio of the target alkali ion conductive solid electrolyte.

[0074] When the alkali ion conductive solid electrolyte is a NASICON-type crystal or Na5XSi4O 12In the case of a crystalline alkali ion conductive solid electrolyte, the alkali ion conductive solid electrolyte precursor solution may be a solution containing an alkali metal element and a transition metal element constituting the alkali ion conductive solid electrolyte, and carbonate ions. In the solution, the alkali metal element is contained in the form of an alkali ion, and the transition metal element is contained in the form of a transition metal ion. The alkali ion conductive solid electrolyte precursor may be, for example, a gelled or dried product of the alkali ion conductive solid electrolyte precursor solution. The alkali ion conductive solid electrolyte may be a fired product of the alkali ion conductive solid electrolyte precursor.

[0075] The alkali metal element in the alkali ion conductive solid electrolyte precursor or its solution is, for example, at least one selected from the group consisting of Li, Na, and K. The transition metal element is, for example, at least one selected from the group consisting of Group 3 and Group 4 elements. The transition metal element is preferably Ti, Zr, Hf, Sc, Y, La, Sm, Dy, or Gd, more preferably Zr, Hf, Sc, Y, La, Sm, Dy, or Gd, even more preferably Zr, Hf, Sc, Y, La, or Sm, and particularly preferably Zr, Hf, Y, La, or Sm. In addition to these transition metal elements, the alkali ion conductive solid electrolyte precursor may contain at least one selected from the group consisting of Ca, Mg, Ba, Sr, Al, Nb, Ta, In, and Ga. In the alkali ion conductive solid electrolyte precursor solution, carbonate ions may be contained as carbonates (carbonates of transition metals) or as a mixture of carbonate ions and carbonates. In the above case, the alkali ion conductive solid electrolyte precursor solution is suitable as a precursor solution for, for example, a sodium ion conductive solid electrolyte.

[0076] The alkali ion conductive solid electrolyte precursor solution may contain nitrate ions instead of carbonate ions, but is preferably a solution containing carbonate ions for the following reasons.

[0077] When a solution containing nitrate ions is used as a precursor solution for an alkali ion-conducting solid electrolyte, the components in the solution tend to precipitate unevenly during mixing and drying, forming heterogeneous phases that cause a decrease in ionic conductivity after firing. Furthermore, the decomposition of nitrate ions during the firing process results in a large weight loss, making it difficult to form a uniform thin film layer. In addition, NO generated during the firing process x This may increase the manufacturing costs for equipment required to treat corrosive gases such as nitrate ions. Furthermore, since solutions containing nitrate ions are strongly acidic, a high level of chemical durability is required for the manufacturing equipment, which may also increase the manufacturing costs.

[0078] On the other hand, when a solution containing carbonate ions is used as the alkali ion-conducting solid electrolyte precursor solution, transition metal elements in transition metal oxides such as ZrO2 and YO3, which normally dissolve only in the acidic range, dissolve by forming complexes through coordination with carbonate ions, allowing the preparation of a metal salt solution with a neutral to weakly basic pH (pH 7 or higher, 7.5 or higher, 8 or higher, 8.5 or higher, and particularly 9 or higher). In this case, the alkali metal components that make up the alkali ion-conducting solid electrolyte can also be dissolved in the solution as carbonates or hydroxides. Furthermore, the silicon component that also makes up the alkali ion-conducting solid electrolyte can be added as water glass (sodium silicate: Na2O·nSiO2). This makes it easy to prepare an alkali ion-conducting solid electrolyte precursor solution.

[0079] In the alkali ion conductive solid electrolyte precursor solution, carbonate ions are preferably bidentate to the transition metal element, which makes it easier for the transition metal element to exist stably in the solution.

[0080] In addition, NR4 is used as a counter ion for carbonate ions. + (wherein each R is independently at least one substituent selected from the group consisting of H, CH, CH, and CHCHOH) This makes it easier for the transition metal element to exist stably in solution.

[0081] The alkali ion conductive solid electrolyte precursor solution can be obtained, for example, by mixing water glass (sodium silicate), tripolyphosphate, and an aqueous solution of ammonium zirconium carbonate.

[0082] Conductive additive 6; For example, conductive carbon can be used as the conductive additive 6. Examples of conductive carbon include acetylene black, carbon black, ketjen black, carbon nanotubes, and vapor grown carbon fiber (VGCF) conductive additives. The conductive additive 6 is preferably a carbon-based conductive additive made of the above-mentioned materials.

[0083] binder; Binders are materials used to bind raw materials (raw material powders) together. Examples of binders include water-soluble polymers such as cellulose derivatives (e.g., carboxymethyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, ethyl cellulose, hydroxyethyl cellulose, and hydroxymethyl cellulose) and polyvinyl alcohol; thermosetting resins (e.g., thermosetting polyimide, phenolic resin, epoxy resin, urea resin, melamine resin, unsaturated polyester resin, and polyurethane); polycarbonate resins (e.g., polyvinylidene fluoride, polyacrylic acid, sodium polyacrylate, polyacrylonitrile, polyethylene oxide, and butyral resin);

[0084] solid electrolyte layer 2; A solid electrolyte similar to the alkali ion conductive solid electrolyte in the sintered electrode 3 can be used.

[0085] Current collector 4; The material of the current collector 4 is not particularly limited, but metal materials such as aluminum, nickel, titanium, silver, copper, stainless steel, tungsten, or alloys thereof can be used. The above metal materials may be used alone or in combination. These alloys are alloys containing at least one of the above metals.

[0086] The effects of the present invention will be described in detail below by comparing examples and comparative examples.

[0087] [Example 1] <Preparation of alkali ion conductive solid electrolyte precursor> The composition ratio is Na3Zr2Si2PO 12 In order to obtain NASICON-type crystals, water glass (sodium silicate: Na2O·nSiO2), ammonium zirconium carbonate aqueous solution ((NH4)2Zr(OH)2(CO3)2), sodium tripolyphosphate (Na5P3O 10 ) was weighed out in total. These were added to 150 g of pure water and stirred at 50°C for 24 hours using a hot stirrer. This gave an alkali ion conductive solid electrolyte precursor solution (pH = 9.7). Next, this solution was allowed to stand overnight in a thermostatic bath at approximately 5°C to cause gelation. In this way, an alkali ion conductive solid electrolyte precursor was prepared.

[0088] <Preparation of a mixture of alkali ion conductive solid electrolyte precursor and carbon electrode material precursor> A mixture was obtained by mixing sucrose (cane sugar), a hard carbon source, which is a carbon electrode material precursor, and an alkali ion conductive solid electrolyte precursor in a weight ratio of 4:1 in a stirrer for 1 hour. The mixture was then dried in a thermostatic chamber at 60°C for 12 hours, and then vacuum dried at 100°C for 6 hours, after which it was pulverized in an agate mortar to obtain a powder.

[0089] <Preparing electrode paste> A powder mixture of an alkali ion conductive solid electrolyte precursor and a carbon electrode material precursor and a conductive additive (acetylene black) were weighed out at a weight ratio of 19:1. A PPC (polypropylene carbonate) binder was added to the mixture at an external ratio of 15 wt%, and the mixture was mixed in an N-methylpyrrolidone solvent using a planetary mixer to obtain an electrode paste.

[0090] <Production of battery components> 500μm thick Na3Zr2Si2PO 12 A solid electrolyte layer made of Na3Zr2Si2PO4 was separately prepared. An electrode paste was applied to a first main surface of the solid electrolyte layer to a thickness of 70 μm and dried in a dryer at 50°C to form an electrode-forming material layer. After drying, the layer was fired at 1000°C for 2 hours in a nitrogen atmosphere (N2: 99.9999%) to form Na3Zr2Si2PO4. 12 A sintered electrode was obtained by precipitating a mixed phase of an alkali ion conductive solid electrolyte having the composition and a carbon electrode material made of hard carbon. Next, a current collector was formed on the sintered electrode by sputtering. The current collector was made of an aluminum thin film. In this way, a battery component was obtained. The sintered electrode in this example was a negative electrode.

[0091] <Preparation of test battery> In a glove box, metallic sodium was attached as a counter electrode to the second main surface of the solid electrolyte layer to prepare a test battery.

[0092] [Comparative Example] A test battery was fabricated in the same manner as in Example 1, except that the negative electrode was a mixture of hard carbon and a PEO (polyethylene oxide)-based polymer solid electrolyte (a mixture of PEO and NaPF6 in a weight ratio of 9:1).

[0093] <Charge / discharge test> A charge / discharge test was performed on the test battery in a thermostatic chamber at 30°C. Specifically, charging (insertion of sodium ions) was performed at a cutoff voltage of 0.001V, and discharging (desorption of sodium ions) was performed at a cutoff voltage of 2.5V, and the charge capacity and discharge capacity were measured. In Example 1, the actual capacity was defined as the weight of the prepared negative electrode, i.e., the sintered electrode, multiplied by 300 mAh / g, and the current value was set to a 0.1 C rate for charging and discharging. The charge capacity and discharge capacity were also measured at 60°C in the same manner as above.

[0094] 4 and 5 are diagrams showing the results of a charge-discharge test of a comparative example and an example 1, respectively.

[0095] As shown in Figure 4, in the comparative example, both the charge capacity and discharge capacity were approximately 250mAh / g to 280mAh / g at 60°C. However, at 30°C, both the charge capacity and discharge capacity were less than 10mAh / g, and the battery did not function satisfactorily. This difference is due to the large change in ionic conductivity with temperature in polymer-based electrodes.

[0096] In contrast, as shown in Figure 5, in Example 1, both the charge capacity and discharge capacity exceeded 350 mAh / g not only at 60°C but also at 30°C. As such, it is clear that a battery using the battery member of the present invention operates satisfactorily even at a low temperature of 30°C. Furthermore, because no organic electrolyte is required, the risk of fire is low, thereby improving safety.

[0097] Next, the effects of the present invention regarding the alkali ion conductive solid electrolyte precursor solution will be described in detail by comparing examples and reference examples.

[0098] [Example 2] An alkali ion conductive solid electrolyte precursor solution was obtained in the same manner as in Example 1. This solution was allowed to stand overnight in a thermostatic bath at about 5°C to gelate it, thereby obtaining an alkali ion conductive solid electrolyte precursor.

[0099] The obtained alkali ion conductive solid electrolyte precursor was dried in a thermostatic chamber at 60°C for 12 hours, and then vacuum dried at 100°C for 6 hours. The dried alkali ion conductive solid electrolyte precursor was analyzed by XRD, and as shown in the XRD chart in Figure 7, it was found to be amorphous and that each component was uniformly dispersed.

[0100] The dried alkali ion conductive solid electrolyte precursor was calcined at 1000°C for 3 hours to obtain an alkali ion conductive solid electrolyte. The obtained alkali ion conductive solid electrolyte was analyzed by XRD and found to contain the desired NASICON-type crystal (NaZrSiPO 12 ) was confirmed to have precipitated (the plot "●" in the chart of "Example 2 after firing" in Figure 7 indicates Na3Zr2Si2PO 12 The ionic conductivity of the alkali ion-conducting solid electrolyte was measured and found to be 1.5 × 10 -4 It was S.

[0101] The ionic conductivity was measured by forming a gold electrode as an ion-blocking electrode on the surface of the alkali ion conductive solid electrolyte, and then measuring the conductivity between 1 and 10 by the AC impedance method. 7 Measurements were performed in the frequency range of 100 Hz, and the resistance was calculated from the Cole-Cole plot. The ionic conductivity was calculated from the obtained resistance value. The measurements using the AC impedance method were performed at 20°C.

[0102] [Reference example] An alkali ion conductive solid electrolyte precursor was obtained in the same manner as in Example 2, except that an aqueous zirconium nitrate solution (ZrO(NO3)2) was used instead of the aqueous zirconium ammonium carbonate solution.

[0103] The obtained alkali ion conductive solid electrolyte precursor was dried in the same manner as in Example 2, and the dried alkali ion conductive solid electrolyte precursor was analyzed by XRD (X-ray diffraction). As shown in FIG. 7, sodium nitrate was precipitated and the precursor was found to be heterogeneous (the plot "◯" in the chart of "Reference Example After Drying" in FIG. 7 indicates the peak position of sodium nitrate crystals).

[0104] The dried alkali ion conductive solid electrolyte precursor was calcined at 1000°C for 3 hours to obtain an alkali ion conductive solid electrolyte. The obtained alkali ion conductive solid electrolyte was analyzed by XRD and found to be composed of a NASICON-type crystal (NaZrSiPO 12 The ionic conductivity of the alkali ion conductive solid electrolyte was measured in the same manner as in Example 2, and was found to be 6.0 × 10 -7 This is thought to be due to the low ionic conductivity of the precipitated heterogeneous phase.

[0105] The manufacturing method of the battery component 1 according to the first embodiment described above includes a heating step at approximately 1000°C. Therefore, the sintered electrode 3 is unlikely to decompose even if it is subjected to a second heat treatment. For example, the sintered electrode 3 can absorb and release alkali ions at 30°C after being heat-treated in an inert atmosphere at 500°C. This effectively improves heat resistance. On the other hand, when a typical electrode containing a binder as a solid electrolyte is heat-treated in an inert atmosphere at 500°C, the binder decomposes and loses its function as a solid electrolyte, making it unable to absorb and release alkali ions at 30°C. It has been found that the sintered electrode 3 of the present invention is unlikely to decompose even when a voltage of approximately 8V to 9V is applied. For example, FIG. 6 shows the results of a charge-discharge test of the test battery prepared in Example 1 above, where the battery was charged and discharged at a cutoff voltage of 9V to 0.001V. As shown in FIG. 6, even when a high voltage of 9V was applied, no plateau due to decomposition was observed, and reversible charge-discharge was possible with a charge-discharge efficiency of 90% or more. In this way, the voltage resistance can be improved. Moreover, the carbon electrode material precursor used to prepare the sintered electrode 3 can be sugar such as sucrose or biomass, which are easily available. Therefore, productivity can be effectively improved.

[0106] In the example described above, water is used as the solvent when mixing the alkali ion conductive solid electrolyte precursor and the carbon electrode material precursor. In particular, sugars such as sucrose have high solubility in water, which effectively increases the homogeneity of the mixture when mixing the alkali ion conductive solid electrolyte precursor and the carbon electrode material precursor. In the battery component of this embodiment, the alkali ion conductive solid electrolyte and the carbon electrode material precursor are homogeneously mixed before obtaining them, which effectively increases the contact area and enables high-power, high-speed charging and discharging.

[0107] Another example of the method for producing a battery member will be described below.

[0108] [Manufacturing method] Hereinafter, the methods for manufacturing battery members or sintered electrodes according to second to ninth embodiments of the present invention will be described.

[0109] (Second embodiment) 8(a) and 8(b) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to the second embodiment. First, an electrode paste 13B and a solid electrolyte layer 2 shown in Fig. 8(a) are prepared. The paste 13B is an electrode-forming material layer in the present invention.

[0110] To obtain the paste 13B, a powder mixture of an alkali ion conductive solid electrolyte precursor and a carbon electrode material precursor is obtained in the same manner as in the manufacturing method according to the first embodiment. Next, the powder mixture is fired in an N2 atmosphere at 200°C or higher and 800°C or lower. Taking into account the firing temperature in the second firing step described below, the upper limit may be set to 500°C or lower. In this way, a carbon electrode material is obtained from the carbon electrode material precursor. This step is the first firing step. The first firing step produces a powder mixture of an alkali ion conductive solid electrolyte precursor and a carbon electrode material. If the firing temperature is too low, the carbon electrode material precursor is less likely to be converted into the carbon electrode material. On the other hand, if the firing temperature is too high, the alkali ion conductive solid electrolyte precursor tends to be converted into the alkali ion conductive solid electrolyte.

[0111] Next, the powder of the mixture is pulverized and further mixed with a conductive additive 6 and a binder in an organic solvent to obtain a paste 13B. Next, as shown in FIG. 8(a), the paste 13B is applied to the first main surface 2a of the solid electrolyte layer 2. A lamination step is performed to laminate the solid electrolyte layer 2 and the paste 13B as an electrode-forming material layer. Next, the laminate of the solid electrolyte layer 2 and the paste 13B is fired in an N2 atmosphere at a temperature above 500°C and not higher than 1300°C (preferably above 800°C and not higher than 1150°C). This results in an alkali ion-conductive solid electrolyte from the alkali ion-conductive solid electrolyte precursor, thereby obtaining a mixed phase 5 of the alkali ion-conductive solid electrolyte and the carbon electrode material. This step is the second firing step. In the second firing step, firing is performed at a higher temperature than in the first firing step. The second firing step results in a sintered electrode 3, as shown in FIG. 8(b). In this way, a laminate of the sintered electrode 3 and the solid electrolyte layer 2 is obtained. If the firing temperature is too low, the reaction will be insufficient, making it difficult to obtain the desired sintered electrode 3. As a result, the internal resistance of the sintered electrode 3 will increase, and charge / discharge efficiency will tend to decrease. On the other hand, if the firing temperature is too high, the alkaline component may evaporate from the alkali ion conductive solid electrolyte precursor, making it difficult to obtain an alkali ion conductive solid electrolyte having the desired composition. As a result, the internal resistance of the sintered electrode 3 will increase, and charge / discharge efficiency will tend to decrease. Next, a current collector 4 is formed on the sintered electrode 3. In this manner, a battery member 1 can be obtained.

[0112] 3(a) and 3(b), in the firing process, both a reaction occurs in which the alkali ion conductive solid electrolyte precursor becomes an alkali ion conductive solid electrolyte, and a reaction occurs in which the carbon electrode material precursor becomes a carbon electrode material. Therefore, there are many decomposition components in the firing process, and the difference between the thickness of the paste 13A and the thickness of the sintered electrode 3 is large. Specifically, the thickness of the sintered electrode 3 tends to be thinner than the thickness of the paste 13A.

[0113] In contrast, in this embodiment, the first firing step is performed before the step of forming the electrode-forming material layer, i.e., the step of forming the paste 13B. As a result, a reaction to obtain a carbon electrode material from the carbon electrode material precursor occurs before the formation of the paste 13B. Therefore, the amount of decomposition components in the second firing step after the formation of the paste 13B is small. Therefore, the difference between the thickness of the paste 13B and the thickness of the sintered electrode 3 is small. Therefore, the thickness of the sintered electrode 3 can be easily adjusted. Additionally, even if the thickness of the paste 13B is increased, defects such as cracks are unlikely to occur in the sintered electrode 3 obtained after firing. As a result, the thickness of the sintered electrode 3 can be easily increased, and therefore the capacitance can be easily increased. However, in the first embodiment, the firing step to obtain the sintered electrode 3 is performed only once, simplifying the process.

[0114] (Third embodiment) 9(a) and 9(b) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to the third embodiment. First, an electrode paste 13C and a solid electrolyte layer 2 shown in FIG. 9(a) are prepared. The paste 13C is an electrode-forming material layer in the present invention.

[0115] To obtain Paste 13C, a powder mixture of an alkali ion conductive solid electrolyte precursor and a carbon electrode material precursor is obtained in the same manner as in the manufacturing method according to the first embodiment. Next, the powder mixture is fired in an N2 atmosphere at a temperature above 500°C and not higher than 1150°C (preferably above 800°C and not higher than 1100°C). This simultaneously produces an alkali ion conductive solid electrolyte and a carbon electrode material. This step is the third firing step. The third firing step produces a powder mixture of an alkali ion conductive solid electrolyte and a carbon electrode material. If the firing temperature is too low, it is difficult to obtain a powder mixture of an alkali ion conductive solid electrolyte and a carbon electrode material. On the other hand, if the firing temperature is too high, the alkali component may evaporate from the alkali ion conductive solid electrolyte precursor, making it difficult to obtain an alkali ion conductive solid electrolyte having the desired composition.

[0116] Next, the powder of the mixture is pulverized and further mixed with a conductive additive 6 and a binder in an organic solvent to obtain a paste 13C. Next, as shown in FIG. 9(a), the paste 13C is applied to the first main surface 2a of the solid electrolyte layer 2. A lamination step is performed to laminate the solid electrolyte layer 2 and the paste 13C as an electrode-forming material layer. Next, the laminate of the solid electrolyte layer 2 and the paste 13C is fired in an N2 atmosphere at a temperature of 600°C or higher and 1300°C or lower (preferably 900°C or higher and 1250°C or lower). This step is the fourth firing step. The fourth firing step is performed at a temperature higher than that of the third firing step. The fourth firing step results in a sintered electrode 3, as shown in FIG. 9(b). If the firing temperature is too low, the sinterability of the sintered electrode 3 and the bonding between the sintered electrode 3 and the solid electrolyte layer 2 may be insufficient. As a result, the internal resistance of the sintered electrode 3 increases, and the charge / discharge efficiency tends to decrease. On the other hand, if the firing temperature is too high, the alkaline component may evaporate from the alkali ion conductive solid electrolyte precursor, making it difficult to obtain an alkali ion conductive solid electrolyte having the desired composition. As a result, the internal resistance of the sintered electrode 3 tends to increase and the charge / discharge efficiency tends to decrease. Next, a current collector 4 is formed on the sintered electrode 3. In this manner, a battery member 1 can be obtained.

[0117] In this embodiment, a third firing step is performed before the step of forming the paste 13C. As a result, both the reaction of the alkali ion conductive solid electrolyte precursor to form the alkali ion conductive solid electrolyte and the reaction of the carbon electrode material precursor to form the carbon electrode material occur before the formation of the paste 13C. Therefore, the amount of decomposition components in the fourth firing step after the formation of the paste 13C is even smaller. Therefore, the difference between the thickness of the paste 13C and the thickness of the sintered electrode 3 is even smaller. This makes it even easier to adjust the thickness of the sintered electrode 3. Additionally, the thickness of the sintered electrode 3 can be increased even more easily, thereby increasing the capacity even more easily. However, in the second embodiment, the battery component 1 can be manufactured at a lower temperature than in the third embodiment.

[0118] (Fourth embodiment) 10(a) and 10(b) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to a fourth embodiment. First, a powder compact 23A shown in FIG. 10(a) and a paste 22 containing a solid electrolyte precursor are prepared. The powder compact 23A is the electrode-forming material layer of the present invention. The paste 22 is the solid electrolyte-forming material layer of the present invention. In this specification, the solid electrolyte-forming material layer refers to a material layer for obtaining (forming) a solid electrolyte layer by firing. The solid electrolyte-forming material layer may be made of, for example, a paste as in this embodiment, or may be made of a powder compact.

[0119] To obtain the powder compact 23A, a powder mixture of an alkali ion conductive solid electrolyte precursor and a carbon electrode material precursor is obtained in the same manner as in the manufacturing method according to the first embodiment. Next, the powder mixture and the conductive additive 6 are mixed together, and the mixture is press-molded to obtain the powder compact 23A of the alkali ion conductive solid electrolyte precursor, the carbon electrode material precursor, and the conductive additive 6. For press-molding, a uniaxial press or the like may be used, for example. Note that the conductive additive 6 does not necessarily have to be added.

[0120] On the other hand, the paste 22 can be obtained by adding the mixed raw material powders to an organic solvent. Next, as shown in FIG. 10(a), the paste 22 is applied to an appropriate substrate 27. The substrate 27 can be a plate made of an appropriate metal, ceramic, or the like. Next, a powder compact 23A is laminated on the paste 22. Next, the laminate of the paste 22 and the powder compact 23A is fired in an N2 atmosphere at a temperature above 500°C and below 1300°C (preferably above 800°C and below 1150°C). As a result, as shown in FIG. 10(b), a solid electrolyte layer 2 and a sintered electrode 3 are simultaneously obtained. In this way, a laminate of the solid electrolyte layer 2 and the sintered electrode 3 is obtained. If the firing temperature is too low, the reaction will be insufficient, making it difficult to obtain the desired sintered electrode 3. Furthermore, it will be difficult to obtain the desired solid electrolyte layer 2. Furthermore, the bonding between the sintered electrode 3 and the solid electrolyte layer 2 may be insufficient. As a result, the internal resistance of the sintered electrode 3 increases, tending to reduce charge / discharge efficiency. On the other hand, if the firing temperature is too high, the alkaline component may evaporate from the alkali ion conductive solid electrolyte precursor, making it difficult to obtain an alkali ion conductive solid electrolyte having the desired composition. As a result, the internal resistance of the sintered electrode 3 tends to increase, and the charge / discharge efficiency tends to decrease. Next, as shown in FIG. 10(b), the laminate of the solid electrolyte layer 2 and the sintered electrode 3 is peeled off from the substrate 27, and a current collector 4 is formed on the sintered electrode 3. Alternatively, the laminate of the solid electrolyte layer 2 and the sintered electrode 3 may be peeled off from the substrate 27 after the current collector 4 is formed on the sintered electrode 3. In this manner, the battery member 1 can be obtained.

[0121] In this embodiment, the solid electrolyte layer 2 and the sintered electrode 3 are obtained simultaneously, thereby improving productivity. In addition, the paste 22 is used to prepare the solid electrolyte layer 2, so the solid electrolyte layer 2 can be easily thinned. Modifications of this embodiment will be described below.

[0122] (Modification 1 of the fourth embodiment) 11(a) to 11(c) are schematic cross-sectional views illustrating a manufacturing method of a battery member according to Modification 1 of the fourth embodiment. In this modification, as shown in FIG. 11(a), a paste 22 is applied to a powder compact 23A. Next, as in the fourth embodiment, a laminate of the paste 22 and the powder compact 23A is fired in an N2 atmosphere at a temperature above 500°C and not higher than 1300°C (preferably above 800°C and not higher than 1150°C). As a result, a solid electrolyte layer 2 and a sintered electrode 3 are simultaneously obtained, as shown in FIG. 11(b). If the firing temperature is too low, the reaction is insufficient, making it difficult to obtain the desired sintered electrode 3. Furthermore, it also makes it difficult to obtain the desired solid electrolyte layer 2. Furthermore, the bonding between the sintered electrode 3 and the solid electrolyte layer 2 may be insufficient. As a result, the internal resistance of the sintered electrode 3 increases, tending to reduce charge / discharge efficiency. On the other hand, if the firing temperature is too high, the alkaline component may evaporate from the alkali ion conductive solid electrolyte precursor, making it difficult to obtain an alkali ion conductive solid electrolyte having the desired composition. As a result, the internal resistance of the sintered electrode 3 tends to increase, and the charge / discharge efficiency tends to decrease. Next, as shown in FIG. 11(c), a current collector 4 is formed on the sintered electrode 3. In this manner, a battery member 21 can be obtained.

[0123] In the battery member 1 manufactured in the fourth embodiment, as shown in FIG. 1, the outer periphery of the solid electrolyte layer 2 is located outside the outer periphery of the sintered electrode 3 in a plan view. In this specification, "plan view" refers to a direction viewed from above in FIG. 1. On the other hand, as shown in FIG. 11(a), in this modification, a paste 22 is applied onto a powder compact 23A. Therefore, in the battery member 21 shown in FIG. 11(c), the outer periphery of the solid electrolyte layer 2 and the outer periphery of the sintered electrode 3 are located at the same position in a plan view.

[0124] (Modification 2 of the fourth embodiment) 12(a) to 12(c) are schematic cross-sectional views illustrating a manufacturing method of a battery member according to Modification 2 of the fourth embodiment. In this modification, instead of the paste 22 shown in FIG. 10(a), a powder compact 22A shown in FIG. 12(a) is prepared. The powder compact 22A is the solid electrolyte-forming material layer of the present invention. The powder compact 22A can be obtained by press-molding a mixed raw material powder. Next, a powder compact 23A serving as an electrode-forming material layer is stacked on the powder compact 22A serving as the solid electrolyte-forming material layer. Next, as in the fourth embodiment, the stack of the powder compact 22A and the powder compact 23A is fired in an N2 atmosphere at a temperature above 500°C and not higher than 1300°C (preferably above 800°C and not higher than 1150°C). As a result, a solid electrolyte layer 2 and a sintered electrode 3 are simultaneously obtained, as shown in FIG. 12(b). If the firing temperature is too low, the reaction is insufficient, making it difficult to obtain the desired sintered electrode 3. Furthermore, it becomes difficult to obtain the desired solid electrolyte layer 2. Furthermore, the bonding between the sintered electrode 3 and the solid electrolyte layer 2 may be insufficient. As a result, the internal resistance of the sintered electrode 3 tends to increase, and the charge / discharge efficiency tends to decrease. On the other hand, if the firing temperature is too high, the alkaline component may evaporate from the alkali ion conductive solid electrolyte precursor, making it difficult to obtain an alkali ion conductive solid electrolyte having the desired composition. As a result, the internal resistance of the sintered electrode 3 tends to increase, and the charge / discharge efficiency tends to decrease. Next, as shown in Figure 12(c), a current collector 4 is formed on the sintered electrode 3. In this manner, a battery member 21 can be obtained.

[0125] (Fifth embodiment) 13(a) and 13(b) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to the fifth embodiment. First, a powder compact 23B and a paste 22 shown in Fig. 13(a) are prepared. The powder compact 23B is an electrode-forming material layer in the present invention.

[0126] To obtain the powder compact 23B, a powder mixture of an alkali ion conductive solid electrolyte precursor and a carbon electrode material precursor is obtained in the same manner as in the manufacturing method according to the first embodiment. Next, the powder mixture is fired in an N2 atmosphere at a temperature between 200°C and 800°C. The upper limit of the firing temperature may be set to 500°C or less, taking into account the firing temperature in the second firing step described below. This step is the same as the first firing step as in the second embodiment. Specifically, in this step, a powder mixture of an alkali ion conductive solid electrolyte precursor and a carbon electrode material is obtained. If the firing temperature is too low, the carbon electrode material precursor is less likely to be converted into a carbon electrode material. On the other hand, if the firing temperature is too high, the alkali ion conductive solid electrolyte precursor tends to be converted into an alkali ion conductive solid electrolyte. Next, the powder mixture and the conductive additive 6 are mixed together, followed by press molding to obtain the powder compact 23B.

[0127] On the other hand, as shown in FIG. 13(a), a paste 22 serving as a solid electrolyte-forming material layer is applied to an appropriate substrate 27. Next, a powder compact 23B is laminated on the paste 22. Next, the laminate of the paste 22 and the powder compact 23B is fired in an N2 atmosphere at a temperature above 500°C and not higher than 1300°C (preferably above 800°C and not higher than 1150°C). This step is the second firing step similar to that of the second embodiment. As a result, a solid electrolyte layer 2 and a sintered electrode 3 are simultaneously obtained, as shown in FIG. 13(b). In this way, a laminate of the solid electrolyte layer 2 and the sintered electrode 3 is obtained. If the firing temperature is too low, the reaction will be insufficient, making it difficult to obtain the desired sintered electrode 3. Furthermore, it will be difficult to obtain the desired solid electrolyte layer 2. Furthermore, the bonding between the sintered electrode 3 and the solid electrolyte layer 2 may be insufficient. As a result, the internal resistance of the sintered electrode 3 increases, tending to reduce charge / discharge efficiency. On the other hand, if the firing temperature is too high, the alkaline component may evaporate from the alkali ion-conductive solid electrolyte precursor, making it difficult to obtain an alkali ion-conductive solid electrolyte having the desired composition. As a result, the internal resistance of the sintered electrode 3 tends to increase, and charge / discharge efficiency tends to decrease. Next, the laminate of the solid electrolyte layer 2 and the sintered electrode 3 is peeled from the substrate 27, and then the current collector 4 is formed on the sintered electrode 3. In this manner, the battery member 1 can be obtained. In this embodiment, the solid electrolyte layer 2 is obtained simultaneously with the sintered electrode 3, thereby improving productivity. In addition, as in the second embodiment, the thickness of the sintered electrode 3 can be easily adjusted. Furthermore, since the thickness of the sintered electrode 3 can be easily increased, the capacity can be easily increased.

[0128] (Sixth embodiment) 14(a) and 14(b) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to the sixth embodiment. First, a powder compact 23C and a solid electrolyte paste 22 shown in FIG. 14(a) are prepared. The powder compact 23C is an electrode-forming material layer in the present invention.

[0129] To obtain the powder compact 23C, a powder mixture of an alkali ion conductive solid electrolyte precursor and a carbon electrode material precursor is obtained in the same manner as in the manufacturing method according to the first embodiment. Next, the powder mixture is fired in an N2 atmosphere at a temperature above 500°C and not higher than 1150°C (preferably above 800°C and not higher than 1100°C). This simultaneously obtains an alkali ion conductive solid electrolyte and a carbon electrode material. This step is the third firing step, similar to that of the third embodiment. The third firing step produces a powder mixture of an alkali ion conductive solid electrolyte and a carbon electrode material. If the firing temperature is too low, it becomes difficult to obtain a powder mixture of an alkali ion conductive solid electrolyte and a carbon electrode material. On the other hand, if the firing temperature is too high, the alkali component may evaporate from the alkali ion conductive solid electrolyte precursor, making it difficult to obtain an alkali ion conductive solid electrolyte having the desired composition. Next, the powder mixture and the conductive additive 6 are mixed together, followed by press molding to obtain the powder compact 23C.

[0130] On the other hand, as shown in FIG. 14(a), a paste 22 serving as a solid electrolyte-forming material layer is applied to an appropriate substrate 27. Next, a powder compact 23C is laminated on the paste 22. Next, the laminate of the paste 22 and the powder compact 23C is fired in an N2 atmosphere at a temperature of 600°C or higher and 1300°C or lower (preferably, above 800°C and below 1250°C). This step is the fourth firing step similar to that of the third embodiment. By the fourth firing step, a solid electrolyte layer 2 and a sintered electrode 3 are simultaneously obtained, as shown in FIG. 14(b). In this way, a laminate of the solid electrolyte layer 2 and the sintered electrode 3 is obtained. If the firing temperature is too low, the sintering property of the sintered electrode 3 and the bonding property between the sintered electrode 3 and the solid electrolyte layer 2 may be insufficient. As a result, the internal resistance of the sintered electrode 3 increases, tending to reduce charge / discharge efficiency. On the other hand, if the firing temperature is too high, the alkaline component may evaporate from the alkali ion conductive solid electrolyte precursor, making it difficult to obtain an alkali ion conductive solid electrolyte having the desired composition. As a result, the internal resistance of the sintered electrode 3 tends to increase, and the charge / discharge efficiency tends to decrease. Next, the laminate of the solid electrolyte layer 2 and the sintered electrode 3 is peeled from the substrate 27, and then the current collector 4 is formed on the sintered electrode 3. In this manner, the battery member 1 can be obtained.

[0131] In this embodiment, the solid electrolyte layer 2 and the sintered electrode 3 are obtained simultaneously, thereby improving productivity. In addition, as in the third embodiment, it is easier to adjust the thickness of the sintered electrode 3. Furthermore, since the thickness of the sintered electrode 3 can be increased more easily, the capacity can be increased more easily.

[0132] The sintered electrode 3 according to one embodiment of the present invention can also be used alone. An example of a method for manufacturing the sintered electrode 3 will be described below.

[0133] (Seventh embodiment) 15(a) and 15(b) are schematic cross-sectional views illustrating a method for manufacturing a sintered electrode according to the seventh embodiment. First, as shown in FIG. 15(a), a powder compact 23A is prepared in the same manner as in the fourth embodiment. The powder compact 23A is an electrode-forming material layer containing an alkali ion-conductive solid electrolyte precursor, a carbon electrode material precursor, and a conductive additive 6. However, the electrode-forming material layer does not necessarily contain the conductive additive 6. Next, the powder compact 23A is fired in an N2 atmosphere at a temperature above 500°C and not higher than 1300°C (preferably above 800°C and not higher than 1150°C). This simultaneously produces an alkali ion-conductive solid electrolyte and a carbon electrode material, thereby obtaining a mixed phase 5 of the alkali ion-conductive solid electrolyte and the carbon electrode material. In this way, a sintered electrode 3 can be obtained, as shown in FIG. 15(b). If the firing temperature is too low, the reaction is insufficient, making it difficult to obtain the desired sintered electrode 3. As a result, the internal resistance of the sintered electrode 3 tends to increase, and the charge / discharge efficiency tends to decrease. On the other hand, if the firing temperature is too high, the alkaline component may evaporate from the alkali ion-conductive solid electrolyte precursor, making it difficult to obtain an alkali ion-conductive solid electrolyte having the desired composition. As a result, the internal resistance of the sintered electrode 3 tends to increase, and the charge / discharge efficiency tends to decrease.

[0134] (Eighth embodiment) 16(a) and 16(b) are schematic cross-sectional views illustrating a method for manufacturing a sintered electrode according to the eighth embodiment. First, as shown in FIG. 16(a), a powder compact 23B is prepared in the same manner as in the fifth embodiment. Specifically, a powder mixture of an alkali ion-conductive solid electrolyte precursor and a carbon electrode material precursor is fired in an N2 atmosphere at 200°C or higher and 800°C or lower. Note that, taking into account the firing temperature in the second firing step described below, the upper limit may be set to 500°C or lower. In this manner, a carbon electrode material is obtained from the carbon electrode material precursor. This step is the first firing step similar to that in the fifth embodiment. The first firing step produces a powder mixture of an alkali ion-conductive solid electrolyte precursor and a carbon electrode material. If the firing temperature is too low, the carbon electrode material precursor is unlikely to be converted into a carbon electrode material. On the other hand, if the firing temperature is too high, the alkali ion-conductive solid electrolyte precursor tends to be converted into an alkali ion-conductive solid electrolyte. Next, the powder of the mixture and the conductive additive 6 are mixed together, and then press-molded to obtain the green compact 23B.

[0135] Next, the compact 23B is fired in an N2 atmosphere at a temperature above 500°C and not higher than 1300°C (preferably above 800°C and not higher than 1150°C). This produces an alkali ion-conductive solid electrolyte from the alkali ion-conductive solid electrolyte precursor, thereby producing a mixed phase 5 of the alkali ion-conductive solid electrolyte and the carbon electrode material. This step is the second firing step, similar to that of the fifth embodiment. In the second firing step, firing is performed at a higher temperature than in the first firing step. As a result, a sintered electrode 3 is obtained, as shown in FIG. 16(b). If the firing temperature is too low, the reaction is insufficient, making it difficult to obtain the desired sintered electrode 3. As a result, the internal resistance of the sintered electrode 3 tends to increase, and the charge / discharge efficiency tends to decrease. On the other hand, if the firing temperature is too high, the alkali component may evaporate from the alkali ion-conductive solid electrolyte precursor, making it difficult to obtain an alkali ion-conductive solid electrolyte having the desired composition. As a result, the internal resistance of the sintered electrode 3 tends to increase, and the charge / discharge efficiency tends to decrease.

[0136] (Ninth embodiment) 17(a) and 17(b) are schematic cross-sectional views illustrating a method for manufacturing a sintered electrode according to the ninth embodiment. First, as shown in FIG. 17(a), a powder compact 23C is prepared in the same manner as in the sixth embodiment. Specifically, a powder mixture of an alkali ion-conductive solid electrolyte precursor and a carbon electrode material precursor is fired in an N2 atmosphere at a temperature above 500°C and not higher than 1150°C (preferably above 800°C and not higher than 1100°C). This simultaneously produces an alkali ion-conductive solid electrolyte and a carbon electrode material. This step is the third firing step, similar to that in the sixth embodiment. The third firing step produces a powder mixture of an alkali ion-conductive solid electrolyte and a carbon electrode material. If the firing temperature is too low, it is difficult to obtain a powder mixture of an alkali ion-conductive solid electrolyte and a carbon electrode material. On the other hand, if the firing temperature is too high, the alkali component may evaporate from the alkali ion-conductive solid electrolyte precursor, making it difficult to obtain an alkali ion-conductive solid electrolyte having the desired composition. Next, the powder of the mixture and the conductive additive 6 are mixed together, and then press-molded to obtain a green compact 23C.

[0137] Next, the compact 23C is fired in an N2 atmosphere at a temperature of 600°C or higher and 1300°C or lower (preferably 900°C or higher and 1250°C or lower). This step is the fourth firing step, similar to that of the sixth embodiment. In the fourth firing step, firing is performed at a temperature higher than that of the third firing step. As a result, a sintered electrode 3 is obtained, as shown in FIG. 17(b). If the firing temperature is too low, the sinterability of the sintered electrode 3 may be insufficient. As a result, the internal resistance of the sintered electrode 3 tends to increase, and the charge / discharge efficiency tends to decrease. On the other hand, if the firing temperature is too high, the alkali component may evaporate from the alkali ion conductive solid electrolyte precursor, making it difficult to obtain an alkali ion conductive solid electrolyte having the desired composition. As a result, the internal resistance of the sintered electrode 3 tends to increase, and the charge / discharge efficiency tends to decrease.

[0138] [Battery materials] (Second embodiment) 18 is a schematic cross-sectional view showing a battery member according to a second embodiment. This embodiment differs from the first embodiment in the configuration of the sintered electrode 33 and in the absence of a current collector. Except for the above points, the battery member 31 of this embodiment has the same configuration as the battery member 1 of the first embodiment. Note that the battery member 31 may have a current collector.

[0139] The sintered electrode 33 includes a particulate carbon electrode material 38 and a coating layer 39. The particulate carbon electrode material 38 has a D50 of 1 μm. The particulate carbon electrode material 38 is made of graphite or hard carbon. The particulate carbon electrode material 38 preferably has a D50 of 50 μm or less, and more preferably 10 μm or less. This increases the density of the sintered electrode 33. The lower limit of the D50 of the particulate carbon electrode material 38 is not particularly limited, but is, for example, 10 nm, 0.1 μm, 0.3 μm, 0.5 μm, or even 0.6 μm.

[0140] As shown in FIG. 18 , the particulate carbon electrode material 38 is covered with a coating layer 39. The coating layer 39 is made of an alkali ion conductive solid electrolyte. In this embodiment, the alkali ion conductive solid electrolyte has sodium ion conductivity. However, the alkali ion conductive solid electrolyte may also have lithium ion conductivity. The particulate carbon electrode material 38 is bonded to each other via the coating layer 39. Furthermore, the sintered electrode 33 is bonded to the solid electrolyte layer 2 by the coating layer 39.

[0141] The sintered electrode 33 preferably contains a conductive additive 6. By containing the conductive additive 6, a conductive path is formed, thereby reducing the internal resistance of the sintered electrode 33. However, the sintered electrode 33 does not necessarily need to contain the conductive additive 6. The sintered electrode 33 does not contain a binder.

[0142] As with the battery member 1 of the first embodiment, the battery member 31 of this embodiment can also improve safety, heat resistance, and voltage resistance. Furthermore, in the battery member 31 of this embodiment, the thickness of the sintered electrode 33 can be easily increased (higher loading) by appropriately adjusting the amount of particulate carbon electrode material 38. Furthermore, performance can be easily adjusted by selecting the particulate carbon electrode material 38 used. The sintered electrode 33 according to one embodiment of the present invention may be used alone.

[0143] An example of a method for manufacturing the battery member 31 of this embodiment and an example of a method for manufacturing the sintered electrode 33 will be described below.

[0144] [Manufacturing method] Hereinafter, a method for manufacturing a battery member or a method for manufacturing a sintered electrode according to tenth to twelfth embodiments of the present invention will be described.

[0145] (Tenth embodiment) 19(a) and 19(b) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to the tenth embodiment. First, a paste 43 and a solid electrolyte layer 2 shown in Fig. 19(a) are prepared. The paste 43 is an electrode-forming material layer in the present invention.

[0146] To obtain the paste 43, an alkali ion conductive solid electrolyte precursor is prepared in the same manner as in the manufacturing method according to the first embodiment. Furthermore, a particulate carbon electrode material 38 is prepared. The alkali ion conductive solid electrolyte precursor and the particulate carbon electrode material 38 are then mixed and then dried. This results in a powder mixture of the alkali ion conductive solid electrolyte precursor and the particulate carbon electrode material 38. The powder mixture is then added to an organic solvent, and further mixed with a conductive additive 6 and a binder. Examples of the organic solvent that can be used include N-methylpyrrolidone. This results in the paste 43. However, the conductive additive 6 does not necessarily need to be added.

[0147] Next, as shown in FIG. 19(a), a paste 43 is applied to the first main surface 2a of the solid electrolyte layer 2. A lamination step is performed to laminate the solid electrolyte layer 2 and the paste 43 as an electrode-forming material layer. Next, the laminate of the solid electrolyte layer 2 and the paste 43 is fired in an N2 atmosphere at a temperature above 500°C and not higher than 1300°C (preferably above 800°C and not higher than 1150°C). As a result, as shown in FIG. 19(b), an alkali ion-conductive solid electrolyte is obtained from the alkali ion-conductive solid electrolyte precursor, resulting in a coating layer 39 made of the alkali ion-conductive solid electrolyte. At this time, the particulate carbon electrode material 38 is bonded to each other via the coating layer 39, resulting in a sintered electrode 33. Furthermore, a laminate of the sintered electrode 33 and the solid electrolyte layer 2 is obtained. At the same time, the sintered electrode 33 is bonded to the solid electrolyte layer 2 by the coating layer 39. Through the above steps, a battery member 31 is obtained. If the firing temperature is too low, the reaction will be insufficient, making it difficult to obtain the desired sintered electrode 33. As a result, the internal resistance of the sintered electrode 33 will increase, and charge / discharge efficiency will tend to decrease. In addition, the bonding between the sintered electrode 33 and the solid electrolyte layer 2 may become insufficient. On the other hand, if the firing temperature is too high, the alkaline component may evaporate from the alkali ion conductive solid electrolyte precursor, making it difficult to obtain the coating layer 39 made of an alkali ion conductive solid electrolyte having the desired composition. As a result, the internal resistance of the sintered electrode 33 will increase, and charge / discharge efficiency will tend to decrease.

[0148] (Eleventh embodiment) 20(a) and 20(b) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to an eleventh embodiment. First, a powder compact 53 and a paste 22 shown in FIG. 20(a) are prepared. The powder compact 53 is an electrode-forming material layer according to the present invention. The paste 22 is a solid electrolyte-forming material layer according to the present invention.

[0149] To obtain the powder compact 53, a powder mixture of the alkali ion conductive solid electrolyte precursor and the particulate carbon electrode material 38 is obtained in the same manner as in the manufacturing method according to the tenth embodiment. Next, the powder mixture and the conductive additive 6 are mixed together, and then the mixture is press-molded to obtain the powder compact 53.

[0150] On the other hand, the paste 22 can be obtained by adding the mixed raw material powders to an organic solvent. Next, as shown in FIG. 20(a), the paste 22 is applied to a suitable substrate 27. Next, a lamination process is performed in which a green compact 53 serving as an electrode-forming material layer is laminated on the paste 22 serving as a solid electrolyte-forming material layer. Next, the laminate of the paste 22 and the green compact 53 is fired in an N2 atmosphere at a temperature above 500°C and below 1300°C (preferably above 800°C and below 1150°C). As a result, a solid electrolyte layer 2 and a sintered electrode 33 are simultaneously obtained, as shown in FIG. 20(b). In this way, a laminate of the sintered electrode 33 and the solid electrolyte layer 2 is obtained. If the firing temperature is too low, the reaction is insufficient, making it difficult to obtain the desired sintered electrode 33. As a result, the internal resistance of the sintered electrode 33 tends to increase, and charge / discharge efficiency tends to decrease. Furthermore, it becomes difficult to obtain the desired solid electrolyte layer 2. Furthermore, the bonding between the sintered electrode 33 and the solid electrolyte layer 2 may be insufficient. On the other hand, if the firing temperature is too high, the alkaline component may evaporate from the alkali ion conductive solid electrolyte precursor, making it difficult to obtain the coating layer 39 made of an alkali ion conductive solid electrolyte having the desired composition, or the solid electrolyte layer 2. As a result, the internal resistance of the sintered electrode 33 tends to increase, and the charge / discharge efficiency tends to decrease.

[0151] The paste 22 may be applied to the powder compact 53, as in the example shown in Fig. 11(a). Alternatively, a powder compact 22A similar to the example shown in Fig. 12(a) may be prepared instead of the paste 22. In this case, the powder compact 53 serving as the electrode-forming material layer and the powder compact 22A serving as the solid electrolyte-forming material layer may be stacked, and then fired.

[0152] (Twelfth embodiment) 21(a) and 21(b) are schematic cross-sectional views illustrating a method for manufacturing a sintered electrode according to the twelfth embodiment. First, as shown in FIG. 21(a), a powder compact 53 is prepared in the same manner as in the eleventh embodiment. The powder compact 53 is the electrode-forming material layer of the present invention. Next, the powder compact 53 is fired in an N2 atmosphere at a temperature above 500°C and not higher than 1300°C (preferably above 800°C and not higher than 1150°C). This results in a sintered electrode 33, as shown in FIG. 21(b). If the firing temperature is too low, the reaction is insufficient, making it difficult to obtain the desired sintered electrode 33. As a result, the internal resistance of the sintered electrode 33 tends to increase, and the charge / discharge efficiency tends to decrease. On the other hand, if the firing temperature is too high, the alkali component may evaporate from the alkali ion-conductive solid electrolyte precursor, making it difficult to obtain a coating layer 39 made of an alkali ion-conductive solid electrolyte having the desired composition. As a result, the internal resistance of the sintered electrode 33 tends to increase, and the charge / discharge efficiency tends to decrease.

[0153] As in the tenth embodiment shown in FIG. 19(a), the sintered electrode 33 may be obtained by applying a paste 43 as an electrode-forming material layer to an appropriate substrate and then firing it.

[0154] [Battery materials] (Third embodiment) 22 is a schematic cross-sectional view showing a battery member according to a third embodiment. This embodiment differs from the second embodiment in the configuration of the coating layer 49 on the sintered electrode 73. Apart from the above, the battery member 41 of this embodiment has the same configuration as the battery member 31 of the second embodiment.

[0155] The coating layer 49 includes a carbon electrode material and an alkali ion conductive solid electrolyte. The carbon electrode material is a substance included separately from the particulate carbon electrode material 38 and is made of graphite or hard carbon. In this embodiment, the alkali ion conductive solid electrolyte has sodium ion conductivity. However, the alkali ion conductive solid electrolyte may also have lithium ion conductivity. The coating layer 49 includes a mixed phase of the carbon electrode material and the alkali ion conductive solid electrolyte. The mixed phase is in a particulate form. The particulate mixed phase is bonded to each other by sintering. The particles of the particulate carbon electrode material 38 are bonded to each other via the coating layer 49. Furthermore, the sintered electrode 73 is bonded to the solid electrolyte layer 2 by the coating layer 49.

[0156] The battery member 41 of this embodiment can also improve safety, heat resistance, and voltage resistance, similarly to the battery member 1 of the first embodiment. Furthermore, in the battery member 41 of this embodiment, the thickness of the sintered electrode 73 can be easily increased (higher loading) by appropriately adjusting the amount of the particulate carbon electrode material 38. Furthermore, as shown in Example 3 described later, the battery member 41 of this embodiment is characterized by excellent initial charge-discharge efficiency (irreversible capacity).

[0157] [Manufacturing method] Hereinafter, a method for producing a battery member according to the thirteenth embodiment of the present invention will be described.

[0158] (Thirteenth embodiment) 23(a) and 23(b) are schematic cross-sectional views illustrating a method for manufacturing a battery member according to the thirteenth embodiment. First, a paste 83 and a solid electrolyte layer 2 are prepared. The paste 83 is an electrode-forming material according to the present invention.

[0159] To obtain the paste 83, an alkali ion conductive solid electrolyte precursor and a carbon electrode material precursor are prepared in the same manner as in the manufacturing method according to the first embodiment. Furthermore, particulate carbon electrode material 38 is prepared. Next, the alkali ion conductive solid electrolyte precursor, the carbon electrode material precursor, and the particulate carbon electrode material 38 are mixed and then dried. This results in a powder mixture of the alkali ion conductive solid electrolyte precursor, the carbon electrode material precursor, and the particulate carbon electrode material 38. Next, the powder mixture is added to an organic solvent, and further mixed with a conductive additive 6 and a binder. Examples of the organic solvent that can be used include N-methylpyrrolidone. This results in the paste 83. However, the conductive additive 6 does not necessarily have to be added.

[0160] Next, as shown in FIG. 23( a), a paste 83 is applied to the first main surface 2a of the solid electrolyte layer 2. A lamination step is performed to laminate the solid electrolyte layer 2 and the paste 83 as an electrode-forming material layer. Next, the laminate of the solid electrolyte layer 2 and the paste 83 is fired in an N2 atmosphere at a temperature above 500°C and not higher than 1300°C (preferably above 800°C and not higher than 1150°C). This converts the alkali ion conductive solid electrolyte precursor and the carbon electrode material precursor into a mixed phase of the carbon electrode material and the alkali ion conductive solid electrolyte. At the same time, as shown in FIG. 23( b), a coating layer 49 made of the mixed phase is formed on the surface of the particulate carbon electrode material 38. At this time, the particulate carbon electrode material 38 is bonded to each other via the coating layer 49, resulting in a sintered electrode 73. Furthermore, a laminate of the sintered electrode 73 and the solid electrolyte layer 2 is obtained. At the same time, the sintered electrode 73 is bonded to the solid electrolyte layer 2 by the coating layer 49. This completes the battery component 41. If the firing temperature is too low, the reaction will be insufficient, making it difficult to obtain the desired sintered electrode 73. As a result, the internal resistance of the sintered electrode 73 will increase, and charge / discharge efficiency will tend to decrease. Furthermore, the bonding between the sintered electrode 73 and the solid electrolyte layer 2 may become insufficient. On the other hand, if the firing temperature is too high, the alkali component may evaporate from the alkali ion-conductive solid electrolyte precursor, making it difficult to obtain the coating layer 49 containing an alkali ion-conductive solid electrolyte having the desired composition. As a result, the internal resistance of the sintered electrode 73 will increase, and charge / discharge efficiency will tend to decrease.

[0161] As in the 11th embodiment shown in Fig. 20, a battery component may be obtained by applying a paste serving as a solid electrolyte-forming material layer to an appropriate substrate, laminating a green compact serving as an electrode-forming material layer on the paste, and firing the resulting mixture. The green compact may be obtained by mixing a conductive additive with a powder mixture of an alkali ion-conductive solid electrolyte precursor, a carbon electrode material precursor, and a particulate carbon electrode material, followed by press molding. As in the 12th embodiment shown in Fig. 21, a sintered electrode may be obtained by firing the green compact.

[0162] Examples of the battery member according to the third embodiment will be described below.

[0163] [Example 3] The composition ratio is Na3Zr2Si2PO 12 A total of 25 g of water glass (sodium silicate), an aqueous solution of ammonium zirconium carbonate, and sodium tripolyphosphate were weighed out to obtain NASICON-type crystals. These were added to 150 g of pure water and stirred at 50°C for 24 hours using a hot stirrer. This resulted in an alkali ion conductive solid electrolyte precursor solution. Next, this solution was allowed to stand overnight in a thermostatic bath at approximately 5°C to gel it. In this way, an alkali ion conductive solid electrolyte precursor was prepared.

[0164] <Preparation of a mixture of alkali ion conductive solid electrolyte precursor and carbon electrode material precursor> A mixture was obtained by mixing sucrose (cane sugar), a hard carbon source, which is a carbon electrode material precursor, and an alkali ion conductive solid electrolyte precursor in a weight ratio of 4:1 in a stirrer for 1 hour. The mixture was then dried in a thermostatic chamber at 60°C for 12 hours, and then vacuum dried at 100°C for 6 hours, after which it was pulverized in an agate mortar to obtain a powder.

[0165] <Preparing electrode paste> The powder mixture of the alkali ion conductive solid electrolyte precursor and the carbon electrode material precursor and the hard carbon powder (average particle size D 50 = 1 μm) and a conductive additive (acetylene black) were weighed out in a weight ratio of 57:40:3. A PPC (polypropylene carbonate) binder was added to these in an external ratio of 15 wt%, and the mixture was mixed in an N-methylpyrrolidone solvent using a planetary mixer to obtain an electrode paste.

[0166] <Production of battery components> 500μm thick Na3Zr2Si2PO 12A solid electrolyte layer made of was separately prepared. The electrode paste was applied to a first main surface of the solid electrolyte layer to a thickness of 70 μm and dried in a dryer at 50°C. After drying, the electrode was fired at 1000°C for 2 hours in a nitrogen atmosphere (N2: 99.9999%) to obtain a sintered electrode in which the hard carbon powder was covered with a coating layer. The coating layer was made of Na3Zr2Si2PO 12 The sintered electrode was formed by depositing a mixed phase of an alkali ion conductive solid electrolyte having the composition and a carbon electrode material made of hard carbon. Next, a current collector was formed on the sintered electrode by sputtering. The current collector was made of an aluminum thin film. In this way, a battery component was obtained. The sintered electrode in this example was a negative electrode.

[0167] <Preparation of test battery> In a glove box, metallic sodium was attached as a counter electrode to the second main surface of the solid electrolyte layer to prepare a test battery.

[0168] <Charge / discharge test> A charge / discharge test was performed on the test battery in a thermostatic chamber at 60°C. Specifically, charging (insertion of sodium ions) was performed at a cutoff voltage of 0.001V, and discharging (desorption of sodium ions) was performed at a cutoff voltage of 2.5V, and the charge capacity and discharge capacity were measured. In Example 3, the actual capacity was calculated as the weight of the prepared negative electrode, i.e., the sintered electrode, multiplied by 300 mAh / g, and charging and discharging were performed at a current value set to a 0.1 C rate. The results of the charge / discharge test are shown in Figure 24.

[0169] 24, the charge capacity was 379 mAh / g, the discharge capacity was 293 mAh / g, and the initial charge / discharge efficiency was 77.3%. Since the initial charge / discharge efficiency at 60°C was 68% in Example 1 relating to the battery member according to the first embodiment of the present invention described above, it can be seen that Example 3 relating to the battery member according to the third embodiment has a better initial charge / discharge efficiency.

[0170] The above describes an embodiment in which a carbon electrode material made of graphite or hard carbon is used as the active material. While carbon electrode materials made of graphite or hard carbon are primarily used as negative electrode active materials, the present invention can also be applied when a positive electrode active material is used instead of the carbon electrode material. For example, in the battery member according to the second embodiment of the present invention shown in FIG. 18 and the manufacturing methods of battery members according to the tenth to twelfth embodiments of the present invention shown in FIGS. 19 to 21, a positive electrode active material can be used instead of the particulate carbon electrode material 38. By doing so, a sintered electrode containing a positive electrode active material and an alkali ion conductive solid electrolyte can be obtained. Alternatively, a battery member can be obtained that includes a solid electrolyte layer and the sintered electrode laminated on the solid electrolyte layer. The positive electrode active material is not particularly limited, but may be, for example, a compound represented by the general formula Na x M y P2O z (M is at least one transition metal element selected from Fe, Cr, Mn, Co and Ni, 1.20≦x≦2.10, 0.95≦y≦1.60) and glass-ceramics are exemplified.

[0171] [Example 4] <Preparation of alkali ion conductive solid electrolyte precursor> The composition ratio is Li7La3Zr2O 12 A total of 25 g of lithium acetate dihydrate (CH3COOLi·2H2O), lanthanum acetate pentadecahydrate (La(CH3COO)3·1.5H2O), and zirconium(IV) propoxide solution (Zr(OCH2CH2CH3)4) were weighed out to obtain crystals of the above. These were added to 150 g of pure water and stirred at 50°C for 24 hours using a hot stirrer. This yielded an alkali ion conductive solid electrolyte precursor solution. Next, this solution was allowed to stand overnight in a thermostatic bath at approximately 5°C to gel it. This resulted in the preparation of an alkali ion conductive solid electrolyte precursor.

[0172] <Preparation of a mixture of alkali ion conductive solid electrolyte precursor and carbon electrode material precursor> A powder mixture of the alkali ion conductive solid electrolyte precursor and the carbon electrode material precursor was obtained in the same manner as in Example 1 using sucrose (cane sugar) as a hard carbon source, which is a carbon electrode material precursor, and the alkali ion conductive solid electrolyte precursor obtained above.

[0173] <Preparing electrode paste> An electrode paste was obtained in the same manner as in Example 1 using the powder mixture of the alkali ion conductive solid electrolyte precursor and the carbon electrode material precursor obtained above.

[0174] <Production of battery components> 500 μm thick Li7La3Zr2O 12 A solid electrolyte layer made of Li7La3Zr2O was separately prepared. An electrode paste was applied to a first main surface of the solid electrolyte layer to a thickness of 70 μm and dried in a dryer at 50°C to form an electrode-forming material layer. After drying, the layer was fired at 1000°C for 2 hours in a nitrogen atmosphere (N2: 99.9999%) to form Li7La3Zr2O 12 A sintered electrode was obtained by precipitating a mixed phase of an alkali ion conductive solid electrolyte having the composition and a carbon electrode material made of hard carbon. Next, a current collector was formed on the sintered electrode by sputtering. The current collector was made of a copper thin film. In this way, a battery component was obtained. The sintered electrode in this example was a negative electrode.

[0175] <Preparation of test battery> In a glove box, metallic lithium was attached as a counter electrode to the second main surface of the solid electrolyte layer to prepare a test battery.

[0176] <Charge / discharge test> A charge / discharge test of the test battery was carried out in a thermostatic chamber at 60°C. Specifically, charging (intercalation of lithium ions) was carried out at a cutoff voltage of 0.001V, and discharging (extraction of lithium ions) was carried out at a cutoff voltage of 1.5V, and the charge capacity and discharge capacity were measured. At this time, the actual capacity was defined as the weight of the prepared negative electrode, i.e., the sintered electrode, multiplied by 400mAh / g, and the current value was set to a 0.1C rate, and charging and discharging were carried out. As a result, the charge capacity was 419mAh / g, the discharge capacity was 314mAh / g, and the initial charge / discharge efficiency was 74.9%. [Explanation of symbols]

[0177] 1...Battery components 2...Solid electrolyte layer 2a, 2b...first and second principal surfaces 3...Sintered electrode 4...Current collector 5...Mixed phase 6...Conductive additive 13A~13C...Paste 21...Battery components 22...Paste 22A...Powder compact 23A~23C…Powder compact 27...Base material 31...Battery components 33...Sintered electrode 38...Particulate carbon electrode material 39...Coating layer 41...Battery components 43...Paste 49...Coating layer 53...Powder compact 73...Sintered electrode 83...Paste

Claims

1. a carbon electrode material made of graphite or hard carbon; an alkali ion conductive solid electrolyte; Including, a mixed phase of the carbon electrode material and the alkali ion conducting solid electrolyte; The mixed phase is made of particles, and the average particle size of the particles is 10 μm or less.

2. 2. The sintered electrode according to claim 1, wherein the alkali ion conductive solid electrolyte has sodium ion conductivity.

3. 3. The sintered electrode according to claim 1, wherein the alkali ion conductive solid electrolyte comprises an oxide.

4. The alkali ion conductive solid electrolyte is a NASICON type crystal and has the general formula Na １＋ｘ Zr ２ P ３－ｘ Si ｘ O １２ (0≦x≦3) and a second compound in which a portion of Zr in the first compound is substituted with at least one element selected from the group consisting of Ca, Mg, Ba, Sr, Al, Nb, Ta, In, Ga and Group 3 elements. The sintered electrode according to any one of claims 1 to 3, comprising at least one compound selected from the group consisting of Ca, Mg, Ba, Sr, Al, Nb, Ta, In, Ga and Group 3 elements.

5. The sintered electrode according to any one of claims 1 to 3, wherein the alkali ion conductive solid electrolyte has at least one of β-alumina type crystals and β"-alumina type crystals.

6. The alkali ion conducting solid electrolyte has the general formula Li ７ La ３ Zr ２ O １２ , Li ７ La ３ Zr ２－ｘ M ｘ O １２ (M is at least one selected from Nb, Ga, and Ta, 0<x<2), or Li ７－３ｘ Al ｘ La ３ Zr ２ O １２ The sintered electrode according to any one of claims 1 to 3, having a crystalline phase represented by (0<x<2.3).

7. The sintered body electrode according to any one of claims 1 to 6, comprising 0 wt% to 20 wt% of at least one carbon-based conductive additive selected from carbon black, acetylene black, ketjen black, carbon nanotubes, and vapor-grown carbon fiber (VGCF) conductive additives.

8. The sintered electrode according to any one of claims 1 to 7, which is a negative electrode.

9. The sintered electrode according to any one of claims 1 to 8, which is capable of absorbing and releasing alkali ions at 30°C after heat treatment in an inert atmosphere at 500°C.

10. The sintered electrode according to any one of claims 1 to 9, which can be reversibly charged and discharged with a charge-discharge efficiency of 90% or more when charged and discharged at a cutoff voltage of 9 V to 0.001 V.

11. a solid electrolyte layer; The sintered electrode according to any one of claims 1 to 10, which is laminated on the solid electrolyte layer; A battery component comprising:

12. The battery member according to claim 11, wherein the solid electrolyte layer has a thickness of 5 nm to 1 mm.

13. A battery comprising the battery member according to claim 11 or 12.

14. a mixing step of obtaining a mixture of an alkali ion conductive solid electrolyte precursor and a carbon electrode material precursor by mixing the alkali ion conductive solid electrolyte precursor with a carbon electrode material precursor, the carbon electrode material precursor being a precursor of a carbon electrode material made of graphite or hard carbon; forming an electrode-forming material layer containing the mixture after the mixing step; firing the electrode-forming material layer; A method for manufacturing a sintered electrode, comprising:

15. the electrode-forming material layer is made of a paste or a compact containing the alkali ion-conductive solid electrolyte precursor and the carbon electrode material precursor, The method for producing a sintered electrode according to claim 14 , wherein the alkali ion conductive solid electrolyte and the carbon electrode material are obtained simultaneously in the step of firing the electrode-forming material layer.

16. In the step of forming the electrode-forming material layer, a first firing step is performed in which the mixture is fired to obtain a carbon electrode material, and then the electrode-forming material layer is formed from a paste or a compact containing the alkali ion conductive solid electrolyte precursor and the carbon electrode material, The method for producing a sintered electrode according to claim 14 , wherein an alkali ion conductive solid electrolyte is obtained from the alkali ion conductive solid electrolyte precursor in the step of firing the electrode-forming material layer.

17. the method further comprises a third firing step of firing the mixture after the mixing step to simultaneously obtain an alkali ion conductive solid electrolyte and a carbon electrode material; 15. The method for producing a sintered electrode according to claim 14, wherein in the step of forming the electrode-forming material layer, the electrode-forming material layer is formed from a paste or a compact containing the alkali ion conductive solid electrolyte and the carbon electrode material.

18. a mixing step of mixing an alkali ion conductive solid electrolyte precursor with a particulate carbon electrode material made of graphite or hard carbon to obtain a mixture of the alkali ion conductive solid electrolyte precursor and the particulate carbon electrode material; a step of forming an electrode-forming material layer made of a paste or a compact containing the alkali ion conductive solid electrolyte precursor and the particulate carbon electrode material after the mixing step; a step of firing the electrode-forming material layer to obtain an alkali ion-conductive solid electrolyte from the alkali ion-conductive solid electrolyte precursor, thereby obtaining the particulate carbon electrode material covered with a coating layer made of the alkali ion-conductive solid electrolyte; A method for manufacturing a sintered electrode, comprising:

19. a mixing step of obtaining a mixture of an alkali ion conductive solid electrolyte precursor, a carbon electrode material precursor, and a particulate carbon electrode material made of graphite or hard carbon by mixing the alkali ion conductive solid electrolyte precursor, the carbon electrode material precursor, and the particulate carbon electrode material, wherein the carbon electrode material precursor is a precursor of a carbon electrode material made of graphite or hard carbon; After the mixing step, a step of forming an electrode-forming material layer made of a paste or a compact containing the mixture; a step of firing the electrode-forming material layer to obtain an alkali ion-conductive solid electrolyte and a carbon electrode material from the alkali ion-conductive solid electrolyte precursor and the carbon electrode material precursor, thereby obtaining the particulate carbon electrode material covered with a coating layer made of the alkali ion-conductive solid electrolyte and the carbon electrode material; A method for manufacturing a sintered electrode, comprising:

20. A method for manufacturing a battery member including a laminate of a sintered electrode and a solid electrolyte layer, comprising: a mixing step of obtaining a mixture of an alkali ion conductive solid electrolyte precursor and a carbon electrode material precursor by mixing the alkali ion conductive solid electrolyte precursor with a carbon electrode material precursor, the carbon electrode material precursor being a precursor of a carbon electrode material made of graphite or hard carbon; forming an electrode-forming material layer containing the mixture after the mixing step; a step of firing the electrode-forming material layer to obtain a sintered electrode; obtaining a laminate of the sintered electrode and the solid electrolyte layer; A method for manufacturing a battery member, comprising:

21. the electrode-forming material layer is made of a paste or a compact containing the alkali ion-conductive solid electrolyte precursor and the carbon electrode material precursor, The method for producing a battery member according to claim 20 , wherein the electrode-forming material layer is fired to simultaneously obtain an alkali ion conductive solid electrolyte and a carbon electrode material.

22. In the step of forming the electrode-forming material layer, a first firing step is performed in which the mixture is fired to obtain a carbon electrode material, and then the electrode-forming material layer is formed from a paste or a compact containing the alkali ion conductive solid electrolyte precursor and the carbon electrode material, 21. The method for producing a battery member according to claim 20, wherein the step of obtaining the sintered electrode is a second firing step of firing the electrode-forming material layer to obtain an alkali ion-conductive solid electrolyte.

23. the method further comprises a third firing step of firing the mixture after the mixing step to simultaneously obtain an alkali ion conductive solid electrolyte and a carbon electrode material; In the step of forming the electrode-forming material layer, the electrode-forming material layer is formed from a paste or a compact containing the alkali ion conductive solid electrolyte and the carbon electrode material, The method for producing a battery member according to claim 20 , wherein the step of obtaining the sintered electrode is a fourth firing step of firing the electrode-forming material layer.

24. A method for manufacturing a battery member including a laminate of a sintered electrode and a solid electrolyte layer, comprising: a mixing step of mixing an alkali ion conductive solid electrolyte precursor with a particulate carbon electrode material made of graphite or hard carbon to obtain a mixture of the alkali ion conductive solid electrolyte precursor and the particulate carbon electrode material; a step of forming an electrode-forming material layer made of a paste or a compact containing the alkali ion conductive solid electrolyte precursor and the particulate carbon electrode material after the mixing step; a step of sintering the electrode-forming material layer to obtain an alkali ion-conductive solid electrolyte from the alkali ion-conductive solid electrolyte precursor and to obtain the particulate carbon electrode material covered with a coating layer made of the alkali ion-conductive solid electrolyte, thereby obtaining a sintered electrode; obtaining a laminate of the sintered electrode and the solid electrolyte layer; A method for manufacturing a battery member, comprising:

25. The method further includes a lamination step of laminating the solid electrolyte layer and the electrode-forming material layer, The method for producing a battery member according to any one of claims 20 to 24, wherein a step of obtaining the sintered electrode is carried out after the lamination step.

26. The method further includes a lamination step of laminating a solid electrolyte-forming material layer made of a paste or a compact containing a solid electrolyte precursor and the electrode-forming material layer, The method for producing a battery member according to any one of claims 20 to 24, wherein after the lamination step, the electrode-forming material layer and the solid electrolyte-forming material layer are fired to simultaneously obtain the sintered electrode and the solid electrolyte layer.

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