Component for electrical storage device and electrical storage device

Abstract

The present invention provides a component for a storage device and a storage device that use an alkali metal ion as a carrier ion and can improve charge / discharge characteristics. The component is characterized by including: a solid electrolyte layer (2) containing an alkali metal ion-conductive solid electrolyte; an alkali metal layer (3) containing an alkali metal, laminated on the solid electrolyte layer (2); and an electrode layer laminated on the alkali metal layer (3) and containing a material capable of occluding / releasing alkali metal ions.

Description

Technical Field

[0001] The present invention relates to a component for an electrical storage device and an electrical storage device using the same. Background Art

[0002] Lithium ion secondary batteries have established an indispensable position as high-capacity and lightweight power sources in mobile devices, electric vehicles, etc. However, in existing lithium ion secondary batteries, a flammable organic electrolyte is mainly used as the electrolyte, so there is a risk of ignition and the like. As a method for solving this problem, the development of all-solid-state batteries using a solid electrolyte instead of the organic electrolyte is underway. In addition, lithium also has problems such as soaring global raw material prices, and therefore, as an alternative, research on all-solid-state sodium ion batteries has been conducted in recent years.

[0003] Patent Document 1 discloses an example of an all-solid-state sodium ion battery in which a positive electrode, a solid electrolyte layer, and a negative electrode are laminated in this order. The solid electrolyte layer is composed of an oxide solid electrolyte represented by Na 1+y Zr2(SiO4) y (PO4) 3-y (1≤y<3).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2010-015782 Summary of the Invention

[0007] Technical Problem to be Solved by the Invention

[0008] In an all-solid-state battery, it is difficult to form an ion conduction path between the solid electrolyte layer and the electrode layer, and the charge / discharge characteristics are poor.

[0009] An object of the present invention is to provide a component for an electrical storage device and an electrical storage device that use an alkali metal ion as a carrier ion and can improve charge / discharge characteristics.

[0010] Technical Solution for Solving the Technical Problem

[0011] The component for an electrical storage device of the present invention is characterized by including: a solid electrolyte layer containing an alkali metal ion-conductive solid electrolyte; an alkali metal layer laminated on the solid electrolyte layer and containing an alkali metal; and an electrode layer laminated on the alkali metal layer and containing a material capable of occluding / releasing alkali metal ions.

[0012] Preferably, the electrode layer is a negative electrode layer. In this case, it is preferred that the negative electrode active material contained in the negative electrode layer is a compound containing at least one selected from metals, alloys, graphite, and hard carbon and an alkali metal element of the same type as the alkali metal element contained in the alkali metal layer.

[0013] Preferably, at least a part of the negative electrode layer is composed of an alloy containing an alkali metal element of the same type as the alkali metal element contained in the alkali metal layer.

[0014] Preferably, the alkali metal contained in the alkali metal layer diffuses into the negative electrode layer.

[0015] Preferably, the alkali metal element contained in the alkali metal layer is Na, and the negative electrode active material is a compound containing Na.

[0016] Preferably, the negative electrode active material contains at least one element selected from Sn, Bi, Sb, and Pb.

[0017] This is suitable for the case where the electrode layer contains a binder.

[0018] This is suitable for the case where the solid electrolyte layer contains an oxide.

[0019] Preferably, the thickness of the alkali metal layer is 5 nm or more and 500 μm or less.

[0020] The electrical storage device of the present invention is characterized in that it has the above-described electrical storage device component, the electrode layer of the electrical storage device component is the first electrode layer, and the electrical storage device further has a second electrode layer laminated on the solid electrolyte layer so as to sandwich the solid electrolyte layer together with the alkali metal layer.

[0021] Effects of the Invention

[0022] Through the present invention, it is possible to provide an electrical storage device component and an electrical storage device that use alkali metal ions as carrier ions and can improve charge-discharge characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a front cross-sectional view of the electrical storage device component according to the first embodiment of the present invention.

[0024] Figure 2 It is a front cross-sectional view of the electrical storage device component according to a modification of the first embodiment of the present invention.

[0025] Figure 3 It is a front cross-sectional view of the electrical storage device according to the second embodiment of the present invention.

[0026] Figure 4 (a) and Figure 4 (b) are front cross-sectional views for explaining an example of the manufacturing method of the electrical storage device according to the second embodiment of the present invention.

[0027] Figure 5 (a) and Figure 5 (b) are front cross-sectional views showing an example of a method for manufacturing an electrical storage device according to a second embodiment of the present invention.

[0028] Figure 6 (a) and Figure 6 (b) are front cross-sectional views showing an example of a method for manufacturing an electrical storage device according to a second embodiment of the present invention.

[0029] Figure 7 (a) and Figure 7 (b) are front cross-sectional views showing an example of a method for manufacturing an electrical storage device according to a second embodiment of the present invention.

[0030] Figure 8 (a) and Figure 8 (b) are front cross-sectional views showing an example of a method for manufacturing an electrical storage device using a component for an electrical storage device according to a modified example of a first embodiment of the present invention. Detailed Embodiment

[0031] Hereinafter, preferred embodiments will be described. However, the following embodiments are merely illustrative, and the present invention is not limited to the following embodiments. In addition, in the respective drawings, there are cases where components having substantially the same functions are referred to by the same reference numerals.

[0032] [Component for Electrical Storage Device]

[0033] (First Embodiment)

[0034] Figure 1 is a front cross-sectional view of a component for an electrical storage device according to a first embodiment of the present invention. As Figure 1 shown, the component 1 for an electrical storage device includes a solid electrolyte layer 2, an alkali metal layer 3, and a negative electrode layer 4. Specifically, the alkali metal layer 3 is laminated on the solid electrolyte layer 2. The negative electrode layer 4 is laminated on the alkali metal layer 3.

[0035] The solid electrolyte layer 2 contains an alkali metal ion-conductive solid electrolyte. The negative electrode layer 4 is an electrode layer containing a material capable of occluding / releasing alkali metal ions in the present invention. However, an electrode layer containing a material capable of occluding / releasing alkali metal ions is not necessarily a negative electrode layer, and may also be a positive electrode layer.

[0036] As the alkali metal layer 3, an appropriate alkali metal such as Li, Na, or K can be used. The thickness of the alkali metal layer 3 is preferably 5 nm or more, more preferably 50 nm or more, and still more preferably 500 nm or more. Thereby, the solid electrolyte layer 2 and the negative electrode layer 4 can be appropriately joined by the alkali metal layer 3. The upper limit of the thickness of the alkali metal layer 3 is not particularly limited, and is preferably 500 μm or less, for example. If the alkali metal layer 3 is too thick, there is a concern that the safety may be impaired. In the present embodiment, the thickness of the negative electrode layer 4 is thicker than the thickness of the alkali metal layer 3. In this case, the safety can be appropriately improved.

[0037] The negative electrode active material of the negative electrode layer 4 may be a metal foil type or a composite type. When the negative electrode layer 4 is of the composite type, it is preferable that the negative electrode layer 4 contains a conductive additive and a binder. By containing the binder, the powders constituting the negative electrode active material can be appropriately bonded to each other. By containing the conductive additive, a conduction path can be formed, and the internal resistance of the negative electrode layer 4 can be made small.

[0038] At least a part of the negative electrode layer 4 is composed of a compound containing an alkali metal element of the same kind as the alkali metal element contained in the alkali metal layer 3. Specifically, the alkali metal contained in the alkali metal layer 3 diffuses into the negative electrode layer 4. Thereby, the portion near the surface of the negative electrode layer 4 that is in contact with at least the alkali metal layer 3 is composed of a compound containing the above alkali metal element. In addition, when the negative electrode active material of the negative electrode layer 4 is of the metal foil type, the compound containing the above alkali metal element is an alloy containing the above alkali metal element. When the negative electrode active material of the negative electrode layer 4 is of the composite type containing a metal, the compound containing the above alkali metal element may also be an alloy containing the above alkali metal element.

[0039] Here, the negative electrode layer 4 has an outer main surface 4a. The outer main surface 4a is the main surface located on the outer side of the electrical storage device component 1. In the present embodiment, the closer to the outer main surface 4a, the lower the composition ratio of the above alkali metal element in the negative electrode layer 4. Thus, the negative electrode layer 4 has a gradient of the composition ratio of the above alkali metal element. However, the composition ratio of the alkali metal in the negative electrode layer 4 may also be uniform. In addition, the negative electrode layer 4 does not necessarily contain the above alkali metal element.

[0040] The feature of this embodiment is that in the component 1 for a storage device, an alkali metal layer 3 is laminated between a solid electrolyte layer 2 and a negative electrode layer 4. Since both the solid electrolyte layer 2 and the negative electrode layer 4 are in contact with the alkali metal layer 3, an ion conduction path can be easily formed. Moreover, since the alkali metal layer 3 has high flexibility, the surface shape of the alkali metal layer 3 can easily follow the surface shapes of both the solid electrolyte layer 2 and the negative electrode layer 4. Thereby, the adhesion between the alkali metal layer 3 and both the solid electrolyte layer 2 and the negative electrode layer 4 can be effectively improved. Thereby, the ion conduction path can be effectively increased. Therefore, the charge / discharge characteristics of the storage device using the component 1 for a storage device can be improved.

[0041] A current collector layer 5 is laminated on the negative electrode layer 4. Additionally, the current collector layer 5 may not be provided. However, by providing the current collector layer 5, current can be collected with high efficiency.

[0042] (Modification example)

[0043] Figure 2 It is a front cross-sectional view of the component for a storage device according to the modification example of the first embodiment. In the component 11 for a storage device, the negative electrode active material of the negative electrode layer 14 is a metal foil system. The negative electrode layer 14 contains an alloy of a metal capable of occluding / releasing alkali metal ions and a metal not capable of occluding / releasing alkali metal ions. By setting it like this, the volume change of the negative electrode layer 14 caused by the occlusion / release of alkali ions during charge / discharge is alleviated, and the cycle characteristics can be improved. Additionally, no current collector layer is formed on the negative electrode layer 14.

[0044] Preferably, the resistance of the metal not capable of occluding / releasing alkali metal ions used in the negative electrode layer 14 is lower than the resistance of the metal capable of occluding / releasing alkali metal ions used in the negative electrode layer 14. In this case, even without a current collector layer, current can be collected with high efficiency.

[0045] In this modification example, at least a part of the negative electrode layer 14 is composed of a compound containing an alkali metal element of the same kind as the alkali metal element contained in the alkali metal layer 3. Specifically, the part of the negative electrode layer 14 near the surface in contact with at least the alkali metal layer 3 is composed of an alloy containing the above alkali metal element. The closer to the outer main surface 14a, the lower the composition ratio of the above alkali metal element in the negative electrode layer 14.

[0046] The component for a storage device according to the present invention can be used, for example, in storage devices such as all-solid-state batteries.

[0047] [Storage device]

[0048] (Second embodiment)

[0049] Figure 3 It is a front cross-sectional view of the storage device according to the second embodiment of the present invention. AsFigure 3 As shown, the all-solid-state battery 20 as an electrical storage device has a positive electrode layer 26 and the electrical storage device component 1 of the first embodiment. The positive electrode layer 26 is laminated on the solid electrolyte layer 2 of the electrical storage device component 1. Specifically, the positive electrode layer 26 is laminated on the solid electrolyte layer 2 in such a manner as to sandwich the solid electrolyte layer 2 together with the alkali metal layer 3. Further, in the present embodiment, the negative electrode layer 4 is the first electrode layer in the present invention, and the positive electrode layer 26 is the second electrode layer in the present invention. A current collector layer 27 is laminated on the positive electrode layer 26. However, the current collector layer 27 may not be provided.

[0050] The feature of the present embodiment is that, in the electrical storage device component 1, the alkali metal layer 3 is laminated between the solid electrolyte layer 2 and the negative electrode layer 4. Since both the solid electrolyte layer 2 and the negative electrode layer 4 are in contact with the alkali metal layer 3, an ion conduction path can be easily formed. Moreover, since the alkali metal layer 3 has high flexibility, the surface shape of the alkali metal layer 3 can easily follow the surface shapes of both the solid electrolyte layer 2 and the negative electrode layer 4. Thereby, the adhesion between the alkali metal layer 3 and both the solid electrolyte layer 2 and the negative electrode layer 4 can be effectively improved. Thereby, the ion conduction path can be effectively increased. Therefore, the charge and discharge characteristics of the electrical storage device can be improved.

[0051] Further, when the negative electrode layer 4 contains an organic binder, P2O5, SiO2, or the like, a deficient layer where no ions exist may be formed in the ion conduction path, causing carrier ions to be trapped in the deficient layer. As a result, there is a concern that the discharge capacity and cycle characteristics may deteriorate. In view of this, in the electrical storage device component 1, carrier ions can be supplied through the alkali metal layer 3. Thereby, the charge and discharge efficiency and cycle characteristics can also be improved. As described above, the present invention is particularly suitable for the case where the negative electrode layer 4 contains an organic binder or the like as a material that can form a deficient layer.

[0052] Moreover, since the solid electrolyte layer 2 and the negative electrode layer 4 are joined with the alkali metal layer 3 interposed therebetween, it is difficult for the negative electrode layer 4 to peel off. Thereby, the cycle characteristics can be effectively improved. Moreover, even if the loading amount of the negative electrode active material is increased, it is difficult for the negative electrode layer 4 to peel off. Therefore, the capacity can be effectively increased.

[0053] However, when the negative electrode active material of the negative electrode layer 4 contains an oxide such as SnO, a conversion reaction occurs during the first charging. When the alkali metal is Li and the oxide is SnO, the reaction formula of the conversion reaction is represented by SnO + 2Li + + 2e - → Sn + Li2O. The Sn reduced from SnO by the conversion reaction, such as Sn + 4.4Li + + 4.4e - → SnLi 4.4As shown, alloying occurs with Li. Moreover, this alloying is reversible, and Li is released during discharge. + And electrons. The conversion reaction is basically an irreversible reaction. Therefore, during discharge, Li in Li2O is not released. + Nor are the electrons in an amount that reduces SnO in the conversion reaction released. Thus, since electrons are consumed through the conversion reaction, the initial charge-discharge efficiency is liable to deteriorate.

[0054] Here, as described in this embodiment, the negative electrode layer 4 is preferably a compound containing an alkali metal element of the same kind as the alkali metal element contained in the alkali metal layer 3. In this case, for example, when the negative electrode active material contains Sn and the alkali metal element is Li, the negative electrode layer 4 further contains an alloy of Sn and Li. Therefore, during the initial discharge, Li + and electrons in this alloy are released. Thus, even if a conversion reaction occurs during the initial charge, the consumption of electrons can be offset. Therefore, the charge-discharge efficiency can be improved. In this way, this embodiment is particularly suitable for the case where the negative electrode active material of the negative electrode layer 4 contains an oxide.

[0055] Hereinafter, the details of the negative electrode layer 4, the solid electrolyte layer 2, the positive electrode layer 26, the current collector layer 5, and the current collector layer 27, which are electrode layers containing a material capable of occluding / releasing alkali metal ions and used in the all-solid-state battery 20, will be described.

[0056] Negative electrode layer (electrode layer capable of occluding / releasing alkali metal ions):

[0057] When the negative electrode active material of the negative electrode layer 4 is a metal foil system, the negative electrode active material contains a metal or an alloy. Specifically, it is preferable that the negative electrode active material contains at least one element selected from, for example, Al, Si, Ge, Sn, Bi, Sb, and Pb. When Li is used in the alkali metal layer 3, it is particularly preferable that the negative electrode active material contains at least one element selected from Al, Si, Ge, Sn, Sb, and Pb. On the other hand, when Na is used in the alkali metal layer 3, it is particularly preferable that the negative electrode active material contains at least one element selected from Sn, Bi, Sb, and Pb.

[0058] In addition, the negative electrode layer 4 may contain a metal element that does not occlude / release alkali metal ions. Specifically, as a metal element that does not occlude / release Li, Zn, Cu, Ni, Co, Mg, and Mo, etc. can be cited. As a metal element that does not occlude / release alkali metal ions, Zn, Cu, Ni, Co, Si, Al, Mg, Mo, and Fe, etc. can be cited.

[0059] When the negative electrode active material of the negative electrode layer 4 is a metal foil system, examples of the method for forming the negative electrode layer 4 include physical vapor deposition methods such as evaporation or sputtering, and chemical vapor deposition methods such as thermal CVD, MOCVD, and plasma CVD. As other methods for forming the negative electrode layer 4, plating, sol-gel method, and liquid-phase film formation method using spin coating can be cited. It is also possible to stack a metal layer capable of occluding / releasing alkali metal ions on a metal layer containing a metal element that does not occlude / release alkali metal ions using the above methods, and then perform alloying.

[0060] When the negative electrode active material of the negative electrode layer 4 is a composite system, it is preferable that the negative electrode active material contains at least one selected from metal powder, alloy powder, glass powder, graphite, hard carbon, composite oxide, and metal oxide. In addition, as the glass powder, for example, oxide-based glass or sulfide-based glass can be cited. As the composite oxide, for example, P2-Na 0.66 [Li 0.22 Ti 0.78 O2 or Li4Ti5O 12 . As the metal oxide, for example, SnO, Bi2O3, or Fe2O3 can be cited. Among them, carbon materials such as graphite and hard carbon are difficult to adhere to the solid electrolyte layer 2, so it is difficult to form an ion conduction path between the solid electrolyte layer 2 and the negative electrode layer 4. Even in such a case, since the solid electrolyte layer 2 and the negative electrode layer 4 can be adhered through the alkali metal layer 3 in the present embodiment, good battery characteristics can be obtained.

[0061] As the binder, for example, polyacrylic acid or sodium carboxymethyl cellulose (CMC-Na) can be used.

[0062] As the conductive aid, for example, conductive carbon can be used. As the conductive carbon, for example, acetylene black or carbon black can be cited.

[0063] Solid electrolyte layer:

[0064] In the present embodiment, the solid electrolyte layer 2 is formed of an alkali metal ion conductive oxide. As the alkali metal ion conductive oxide, for example, β-alumina or NASICON (sodium superionic conductor) crystal having excellent alkali metal ion conductivity can be cited. Such an oxide solid electrolyte is difficult to soften and flow by heat treatment, so it is difficult to adhere to the negative electrode layer 4, and it is difficult to form an ion conduction path between the solid electrolyte layer 2 and the negative electrode layer 4. Even in such a case, since the solid electrolyte layer 2 and the negative electrode layer 4 can be adhered through the alkali metal layer 3 in the present embodiment, good battery characteristics can be obtained. In addition, materials suitable for the case of using sodium ions as an example of the alkali metal ions serving as carrier ions are exemplified below.

[0065] There are two crystal forms of β-aluminum oxide, namely β-aluminum oxide (theoretical composition formula: Na2O·11Al2O3) and β”-aluminum oxide (theoretical composition formula: Na2O·5.3Al2O3). Since β”-aluminum oxide is a metastable substance, Li2O and MgO are usually added as stabilizers. Compared with β-aluminum oxide, β”-aluminum oxide has higher sodium ion conductivity. Therefore, it is preferred to use β”-aluminum oxide alone or a mixture of β”-aluminum oxide and β-aluminum oxide. More preferably, β”-aluminum oxide stabilized with Li2O (Na 1.7 Li 0.3 Al 10.7 O 17 ) or β”-aluminum oxide stabilized with MgO ((Al 10.32 Mg 0.68 O 16 )(Na 1.68 O)).

[0066] Examples of NASICON crystals include Na3Zr2Si2PO 12 、Na 3.2 Zr 1.3 Si 2.2 P 0.7 O 10.5 、Na3Zr 1.6 Ti 0.4 Si2PO 12 、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 Si2PO 12 、Na 3.6 Ti 0.2 Y 0.7 Si 2.8 O9、Na3Zr 1.88 Y 0.12 Si2PO 12 、Na 3.12 Zr 1.88 Y 0.12 Si2PO 12 、Na 3.6 Zr 0.13 Yb 1.67 Si 0.11 P 2.9 O 12 etc., especially Na 3.12 Zr 1.88 Y0.12 Si2PO 12 Preferred because of excellent sodium ion conductivity.

[0067] The solid electrolyte layer 2 can be manufactured by mixing raw material powders, molding the mixed raw material powders, and then firing. For example, it can be manufactured by firing a green sheet after slurrying the raw material powders to make a green sheet. In addition, it can also be manufactured by the sol-gel method.

[0068] The average particle diameter of the solid electrolyte powder as the raw material powder is preferably 0.05 μm or more and 3 μm or less, more preferably 0.05 μm or more and less than 1.8 μm, further preferably 0.05 μm or more and 1.5 μm or less, and particularly preferably 0.1 μm or more and 1.2 μm or less. When the average particle diameter of the solid electrolyte powder is too small, it is not only difficult to uniformly mix with the positive electrode active material precursor powder, but also there are problems such as a decrease in ion conductivity due to moisture absorption and carbonation, and an excessive reaction with the positive electrode active material precursor powder is promoted. As a result, there is a tendency for the internal resistance of the positive electrode material layer to become high and the voltage characteristics and charge-discharge capacity to decrease. On the other hand, when the average particle diameter of the solid electrolyte powder is too large, since the softening flow of the positive electrode active material precursor powder is significantly hindered, there is a tendency for the smoothness of the obtained positive electrode material layer to be poor, resulting in a decrease in mechanical strength and an increase in internal resistance.

[0069] Positive electrode layer:

[0070] The positive electrode layer 26 is not particularly limited as long as it contains a positive electrode active material capable of occluding / releasing alkali ions and can function as the positive electrode layer 26. In addition, the following materials suitable for the case of using sodium ions as an example of alkali metal ions used as carrier ions are exemplified.

[0071] As the active substance crystal that functions as the positive electrode active material, sodium transition metal phosphate crystals containing Na, M (M is at least one transition metal element selected from Cr, Fe, Mn, Co, V, and Ni), P, and O can be cited. As a specific example, Na2FeP2O7, NaFePO4, Na3V2(PO4)3, Na2NiP2O7, Na 3.64 Ni 2.18 (P2O7)2, Na3Ni3(PO4)2(P2O7), Na2CoP2O7, Na 3.64 Co 2.18 (P2O7)2, etc. are preferred because these sodium transition metal phosphate crystals have high capacity and excellent chemical stability. Among them, triclinic crystals belonging to the space group P1 or P-1, especially the general formula Na x M y P2O z(1.2 ≤ x ≤ 2.8, 0.95 ≤ y ≤ 1.6, 6.5 ≤ z ≤ 8) The crystal shown is preferred because of its excellent cycling characteristics. As other active material crystals that function as the positive electrode active material, NaCrO2, Na 0.7 MnO2, NaFe 0.2 Mn 0.4 Ni 0.4 O2 and other layered sodium transition metal oxide crystals can be cited. In addition, the positive electrode active material crystals contained in the positive electrode layer can be a single phase in which only one kind of crystal is precipitated, or a mixed phase in which multiple kinds of crystals are precipitated.

[0072] In addition, the positive electrode layer 26 may also contain the same binder and conductive assistant as the negative electrode layer 4 described above.

[0073] The positive electrode layer 26 can also be formed, for example, by firing an active material precursor powder such as glass powder. By firing the active material precursor powder, active material crystals are precipitated, and these active material crystals function as the positive electrode active material.

[0074] Current collector layer:

[0075] As the material of the current collector layer 5 and the current collector layer 27, there is no particular limitation, and metal materials such as aluminum, titanium, silver, copper, stainless steel, or their alloys can be used. The above metal materials can be used alone or in combination of multiple kinds.

[0076] As the formation method of the current collector layer 5 and the current collector layer 27, there is no particular limitation, and for example, physical vapor deposition methods such as evaporation or sputtering, and chemical vapor deposition methods such as thermal CVD, MOCVD, and plasma CVD can be cited. As other formation methods of the current collector layer 5 and the current collector layer 27, liquid phase film formation methods using plating, sol-gel method, and spin coating can be cited. In particular, when the current collector layer 5 and the current collector layer 27 are formed by the sputtering method, the adhesion is excellent, so it is preferred.

[0077] [Manufacturing method]

[0078] (The electrical storage device according to the second embodiment)

[0079] Hereinafter, an example of the manufacturing method of the all-solid-state battery 20 as the electrical storage device according to the second embodiment will be described. In addition, when manufacturing the electrical storage device component 1 alone, the formation processes of the positive electrode layer 26 and the current collector layer 27 can be omitted.

[0080] Figure 4 (a) and Figure 4 (b) are front cross-sectional views for explaining an example of the manufacturing method of the electrical storage device according to the second embodiment. Figure 5 (a) and Figure 5(b) is a front cross-sectional view showing an example of a method for manufacturing an electrical storage device according to the second embodiment.

[0081] First, as Figure 4 (a) shows, a solid electrolyte layer 2 is prepared. Then, a positive electrode layer 26 is formed on the solid electrolyte layer 2. Thus, a positive electrode layer-solid electrolyte layer member 32A is obtained. Next, a current collector layer 27 is formed on the positive electrode layer 26 of the positive electrode layer-solid electrolyte layer member 32A. On the other hand, as Figure 4 (b) shows, a current collector layer 5 is prepared. Then, a negative electrode layer 4 is formed on the current collector layer 5.

[0082] Next, as Figure 5 (a) shows, an alkali metal layer 3 is laminated on the solid electrolyte layer 2 of the positive electrode layer-solid electrolyte layer member 32A. Specifically, the separately prepared alkali metal layer 3 is pressed against the surface of the solid electrolyte layer 2. As described above, since the alkali metal layer 3 has high flexibility, the shape of the alkali metal layer 3 can appropriately follow the surface shape of the solid electrolyte layer 2. Thus, an ion conduction path can be easily formed. In addition, the alkali metal layer 3 can also be formed on the solid electrolyte layer 2 by, for example, a sputtering method or a vacuum evaporation method. In this case, the shape of the alkali metal layer 3 can also follow the surface shape of the solid electrolyte layer 2.

[0083] Next, as Figure 5 (b) shows, the alkali metal layer 3 provided on the positive electrode layer-solid electrolyte layer member 32A is pressed against the negative electrode layer 4. Then, an annealing treatment is performed in a state where the positive electrode layer-solid electrolyte layer member 32A, the alkali metal layer 3, and the negative electrode layer 4 are laminated. Thus, the alkali metal contained in the alkali metal layer 3 diffuses into the negative electrode layer 4. Through the above process, a all-solid-state battery 20 is obtained.

[0084] Here, the method of laminating the positive electrode layer-solid electrolyte layer member 32A, the alkali metal layer 3, and the negative electrode layer 4 is not limited to the above description. Other examples of the above lamination method are illustrated.

[0085] Figure 6 (a) and Figure 6 (b) are front cross-sectional views showing an example of a method for manufacturing an electrical storage device according to the second embodiment. Figure 7 (a) and Figure 7 (b) are front cross-sectional views showing an example of a method for manufacturing an electrical storage device according to the second embodiment.

[0086] First, as Figure 6As shown in (a), an alkali metal layer 3 is laminated on the negative electrode layer 4. Thus, the shape of the alkali metal layer 3 can appropriately follow the surface shape of the negative electrode layer 4. Thereby, an ion conduction path can be easily formed. Next, as Figure 6 As shown in (b), the alkali metal layer 3 provided on the negative electrode layer 4 is crimped to the solid electrolyte layer 2 of the positive electrode layer-solid electrolyte layer member 32A. Through the above process, the all-solid-state battery 20 is obtained.

[0087] As another example, first, as Figure 7 As shown in (a), an alkali metal thin film 33B is laminated on the solid electrolyte layer 2 of the positive electrode layer-solid electrolyte layer member 32A. On the other hand, as Figure 7 As shown in (b), an alkali metal thin film 33A is laminated on the negative electrode layer 4. The alkali metal thin film 33A and the alkali metal thin film 33B can be formed, for example, by a sputtering method, a vacuum evaporation method, or the like.

[0088] Next, as Figure 7 As shown in (c), the alkali metal thin film 33A laminated on the negative electrode layer 4 is crimped to the alkali metal thin film 33B laminated on the positive electrode layer-solid electrolyte layer member 32A to integrate them, thereby forming the alkali metal layer 3. In this case, the shape of the alkali metal layer 3 can appropriately follow the surface shapes of both the negative electrode layer 4 and the solid electrolyte layer 2. Thereby, the ion conduction path can be easily increased. Through the above process, the all-solid-state battery 20 is obtained.

[0089] Hereinafter, an example of a method for manufacturing an all-solid-state battery as a power storage device using the power storage device component 11 according to a modification of the first embodiment will be described.

[0090] Figure 8 (a) and Figure 8 (b) are front cross-sectional views for explaining an example of a method for manufacturing a power storage device using the power storage device component according to a modification of the first embodiment.

[0091] First, as Figure 8 As shown in (a), a first metal layer 34A made of a metal that does not occlude / release alkali metal ions is formed. Then, a second metal layer 34B made of a metal that can occlude / release alkali metal ions is laminated on the first metal layer 34A. Next, an annealing treatment is performed on the laminate of the first metal layer 34A and the second metal layer 34B to alloy them, thereby, as Figure 8 As shown in (b), the negative electrode layer 14 is formed.

[0092] On the other hand, the positive electrode layer-solid electrolyte layer member 32A is prepared in the same manner as the method shown in Figure 4 (a). Then, in the same manner as Figure 5 (a) andFigure 5 (b), Figure 6 (a) and Figure 6 (b) or Figure 7 (a) and Figure 7 In the same manner as the method shown in (b), the laminated positive electrode layer - solid electrolyte layer member 32A, the alkali metal layer 3, and the negative electrode layer 14 are stacked.

[0093] Then, in a state where the positive electrode layer - solid electrolyte layer member 32A, the alkali metal layer 3, and the negative electrode layer 14 are stacked, an annealing treatment is performed. As a result, the alkali metal contained in the alkali metal layer 3 diffuses into the negative electrode layer 14. Through the above process, an all-solid-state battery having the member 11 for an electrical storage device is obtained.

[0094] [Examples]

[0095] Hereinafter, the present invention will be described based on examples, but the present invention is not limited to these examples.

[0096] (Example 1)

[0097] (a) Fabrication of the positive electrode layer - solid electrolyte layer member

[0098] 2Na2O - Fe2O3 - 2P2O5 glass that becomes a precursor of the active material is fabricated by the melting method. The obtained 2Na2O - Fe2O3 - 2P2O5 glass is roughly pulverized using a ball mill and then wet pulverized using a planetary ball mill to fabricate glass powder having a D50 of 0.6 μm.

[0099] β''-aluminum oxide (manufactured by Ionotec) is roughly pulverized using a ball mill and then air classified to fabricate solid electrolyte powder having a D50 of 1.7 μm.

[0100] As a conductive additive for the positive electrode layer, acetylene black (manufactured by Timcal, "SuperC65") is used. The glass powder that becomes a precursor of the active material, the solid electrolyte powder, and the conductive additive are mixed at a weight ratio of 72:25:3 to obtain a mixture. Next, 10 parts by weight of poly(propylene carbonate) is added to 100 parts by weight of the obtained mixture as a binder, and N-methyl-2-pyrrolidone is further added as a solvent to prepare a paste.

[0101] On the other hand, a β''-aluminum oxide plate (manufactured by Ionotec) is used for the solid electrolyte layer. The above paste is coated on the solid electrolyte layer and dried. In addition, the paste is coated in such a manner that the loading amount of the positive electrode active material is 4.5 mg / cm 2 In the case where the loading amount of the positive electrode active material is 4.5 mg / cm 2 2, the capacity per unit area of the formed positive electrode layer is 0.44 mAh / cm2 Then, in a mixed gas of N2 / H2 = 96 / 4 v / v%, firing is carried out at 500 °C for 30 minutes to fabricate a positive electrode layer - solid electrolyte layer component.

[0102] Next, on the surface of the positive electrode layer of the positive electrode layer - solid electrolyte layer component, a current collector layer made of Al is formed using a sputtering device. The thickness of the current collector layer is 500 nm.

[0103] (b) Fabrication of the negative electrode layer

[0104] As the negative electrode active material, hard carbon (“BELL FINE LN0001” manufactured by AT Electrode Co., Ltd.) is used. As the conductive additive, acetylene black (“SuperC65” manufactured by Timcal Co., Ltd.) is used. As the binder, sodium carboxymethyl cellulose (manufactured by Daicel Fine Chemical Co., Ltd.) is used. The negative electrode active material, conductive additive, and binder are mixed at a weight ratio of 80:10:10 to obtain a mixture. Then, pure water is added to the obtained mixture and mixed using a rotation / revolution mixer to prepare a slurry. Next, the obtained slurry is coated on an Al foil with a thickness of 18 μm. Additionally, the thickness of the slurry is made 300 μm so that the loading amount of the negative electrode active material becomes 8 mg / cm 2 When the loading amount of the negative electrode active material is 8 mg / cm 2 the capacity per unit area of the formed negative electrode layer is 2.4 mAh / cm 2 Next, the slurry is dried at 70 °C to obtain a dried mixture. Next, in a state where the dried mixture is disposed on the Al foil, it is pressed using a pair of rotating rollers to obtain an electrode sheet. Then, the obtained electrode sheet is punched using an electrode punching machine to form a circular sheet with a diameter of 11 mm. Then, it is dried at 140 °C for 6 hours under reduced pressure to fabricate a circular negative electrode layer.

[0105] (c) Fabrication of the all - solid - state battery

[0106] By rolling and forming metallic sodium, a sodium foil is obtained. Next, the obtained sodium foil is punched using an electrode punching machine to form a circular shape with a diameter of 11 mm. Then, the circular sodium foil is pasted on the surface of the negative electrode layer. Thus, a laminate of the sodium foil as the alkali metal layer and the negative electrode layer is obtained. Additionally, the loading amount of sodium is made 10 mg / cm 2 Then, on the surface of the solid electrolyte layer of the above positive electrode layer - solid electrolyte layer component, the sodium layer pasted on the negative electrode layer is press - bonded. Through the above process, an all - solid - state battery is obtained.

[0107] (d) Fabrication of the test battery

[0108] Place the all-solid-state battery obtained through the above procedures on the lower cover of a button battery, and then cover it with the upper cover to fabricate a CR2032 type test battery. Additionally, the formation of the sodium metal layer in step (c) and step (d) are carried out in an argon atmosphere with a dew point below -70°C.

[0109] (Example 2)

[0110] Except for forming the sodium metal layer by vacuum evaporation in step (c), the all-solid-state battery and the test battery are fabricated in the same manner as in Example 1.

[0111] Specifically, a sodium metal thin film is formed on the surface of the solid electrolyte layer of the positive electrode layer-solid electrolyte layer component by vacuum evaporation. Additionally, the sodium metal thin film is circular with a diameter of 11 mm, and the loading amount of sodium metal is 0.25 mg / cm 2 .

[0112] On the other hand, a sodium metal thin film is also formed on the surface of the negative electrode layer formed in the same manner as in Example 1 by vacuum evaporation. Additionally, the sodium metal thin film is circular with a diameter of 11 mm, and the loading amount of sodium metal is 0.25 mg / cm 2 . After that, the sodium metal thin film formed on the negative electrode layer is crimped with the sodium metal thin film formed on the positive electrode layer-solid electrolyte layer component to integrate them, thereby forming a sodium metal layer and obtaining an all-solid-state battery. Additionally, in Example 2, the loading amount of sodium metal is the sum of the loading amounts of sodium metal in the above-mentioned respective sodium metal thin films, which is 0.5 mg / cm 2 . In Example 2, the formation of the sodium metal layer is also carried out in an argon atmosphere with a dew point below -70°C. After that, the test battery is fabricated in the same manner as in Example 1.

[0113] (Example 3)

[0114] Except for making the loading amount of sodium metal 1 mg / cm 2 (0.5 mg / cm 2 + 0.5 mg / cm 2 ), the all-solid-state battery and the test battery are fabricated in the same manner as in Example 2.

[0115] (Example 4)

[0116] Except for making the loading amount of sodium metal 5 mg / cm 2 , the all-solid-state battery and the test battery are fabricated in the same manner as in Example 1.

[0117] (Example 5)

[0118] In such a way as to achieve 72 mol% of SnO and 28 mol% of P2O5, stannous pyrophosphate Sn2P2O7 is used as the main raw material, and the raw material powder is adjusted by using various oxide raw materials, phosphate raw materials, carbonate raw materials, metallic Sn powder raw material as a reducing agent, carbon raw materials, etc. Then, the raw material powder is put into a quartz crucible and melted by heating at 950 °C for 40 minutes in a nitrogen atmosphere using an electric furnace to obtain a melt. Then, the melt is formed to obtain a film-like glass. After the obtained glass is coarsely pulverized by a ball mill, it is air classified to produce a negative electrode active material powder with an average particle size of 2 μm. In addition, powder X-ray diffraction measurement is performed on the obtained negative electrode active material powder, and the result is amorphous and no crystal is detected.

[0119] Then, the negative electrode active material powder, a conductive additive, and a binder are mixed at a weight ratio of 80:5:15 to obtain a mixture. In addition, the same conductive member and binder as in Example 1 are used. Then, pure water is added to the obtained mixture and mixed using a rotation / revolution mixer to prepare a slurry. After that, the loading amount of metallic sodium is 3 mg / cm 2 , and except for this, a all-solid battery and a test battery are produced in the same manner as in Example 1.

[0120] (Example 6)

[0121] In a sulfuric acid bath obtained by adding sulfuric acid and a semi-brightness additive to stannous sulfate, electroplating treatment is performed on a Cu foil. Semi-bright plating can form a film with a smaller stress than bright plating. In the sulfuric acid bath, stannous sulfate is 20 g / L and sulfuric acid is 150 g / L. Thus, a Sn layer is formed on the Cu foil to obtain an electrode sheet. In Example 6, the negative electrode active material is Sn. In addition, the thickness of the Cu foil is 20 μm, the thickness of the Sn layer is 7 μm, and the loading amount of Sn is 5 mg / cm 2 . When the loading amount of Sn as the negative electrode active material is 5 mg / cm 2 , the capacity per unit area of the formed negative electrode layer is 4.5 mAh / cm 2 . Next, the obtained electrode sheet is punched using an electrode punching machine to be a circular sheet with a diameter of 11 mm. Then, it is dried at 120 °C for 6 hours under reduced pressure to produce a circular negative electrode layer. After that, the loading amount of metallic sodium is 3 mg / cm 2 , and except for this, a all-solid battery and a test battery are produced in the same manner as in Example 1.

[0122] (Comparative Example)

[0123] The negative electrode layer and the positive electrode layer - solid electrolyte layer component produced in the same manner as in Example 1 were directly bonded without intervening a sodium metal layer, and a all-solid-state battery and a test battery were produced in the same manner as in Example 1 except for this.

[0124] (Charge and discharge test)

[0125] For the test batteries of Examples 1 to 6 and the Comparative Example produced, CC (constant current) charging from the open circuit voltage to 5 V was performed at 30°C. Then, CC discharge from 5 V to 2 V was performed at 30°C. During charging and discharging, the C rate was 0.05C.

[0126] The results of the charge and discharge characteristics are shown in Table 1. In the "Charge and Discharge Results" of Table 1, ○ indicates that charge and discharge are possible, and × indicates that charge and discharge are not possible. "Discharge voltage" refers to the average operating voltage during the first discharge.

[0127] [Table 1]

[0128]

[0129] As shown in Table 1, charge and discharge were possible at 2.57 V or higher in Examples 1 to 6. On the other hand, in the Comparative Example where no sodium metal layer was formed, the battery did not operate.

[0130] Explanation of reference numerals

[0131] 1: Component for electrical storage device; 2: Solid electrolyte layer; 3: Alkali metal layer; 4: Negative electrode layer; 4a: Outer main surface; 5: Current collector layer; 11: Component for electrical storage device; 14: Negative electrode layer; 14a: Outer main surface; 20: All-solid-state battery; 26: Positive electrode layer; 27: Current collector layer; 32A: Positive electrode layer - solid electrolyte layer component; 33A: Alkali metal thin film; 33B: Alkali metal thin film; 34A: First metal layer; 34B: Second metal layer.

Claims

1. A component for an electrical storage device, characterized in that, Comprising: A solid electrolyte layer containing an alkali metal ion-conductive solid electrolyte; An alkali metal layer made of metallic sodium, laminated on the solid electrolyte layer; and An electrode layer laminated on the alkali metal layer, containing a material capable of occluding / releasing alkali metal ions.

2. The component for an electrical storage device according to claim 1, wherein: The electrode layer is a negative electrode layer.

3. The component for an electrical storage device according to claim 2, wherein: The negative electrode active material contained in the negative electrode layer is a compound containing at least one selected from metals, alloys, graphite, and hard carbon and sodium.

4. The component for an electrical storage device according to claim 3, wherein: At least a part of the negative electrode layer is made of an alloy containing sodium.

5. The component for an electrical storage device according to claim 3 or 4, wherein: The sodium contained in the alkali metal layer diffuses into the negative electrode layer.

6. The component for an electrical storage device according to claim 3 or 4, wherein: The negative electrode active material is a compound containing Na.

7. The component for an electrical storage device according to claim 3 or 4, wherein: The negative electrode active material contains at least one element selected from Sn, Bi, Sb, and Pb.

8. The component for an electrical storage device according to any one of claims 1 to 4, characterized in that: The electrode layer contains a binder.

9. The component for an electrical storage device according to any one of claims 1 to 4, characterized in that: The solid electrolyte layer contains an oxide.

10. The component for an electrical storage device according to any one of claims 1 to 4, characterized in that: The thickness of the alkali metal layer is 5 nm or more and 500 μm or less.

11. An electrical storage device, wherein: It has the component for an electrical storage device according to any one of claims 1 to 10, The electrode layer of the component for an electrical storage device is a first electrode layer, The electrical storage device further has a second electrode layer laminated on the solid electrolyte layer in such a manner as to sandwich the solid electrolyte layer together with the alkali metal layer.

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