All-solid-state secondary battery

Abstract

Provided is an all-solid-state secondary battery in which a short circuit hardly occurs between a positive electrode side collector and a negative electrode side collector.　An all-solid-state secondary battery 1 comprises: an electricity storage element 2 having a solid-state electrolyte layer 3, a positive electrode layer 4, and a negative electrode layer 5; a first collector layer 6 provided on a primary surface 2a on one side of the electricity storage element 2; a second collector layer 7 provided on a primary surface 2b on the other side of the electricity storage element 2; and a sealing layer 8 provided between the first collector layer 6 and the second collector layer 7 and sealing the electricity storage element 2. The sealing layer 8 has a first sealing layer portion 9, a second sealing layer portion 10, and an insulating layer portion 11 having a volume resistance higher than those of the first sealing layer portion 9 and the second sealing layer portion 10. The insulating layer portion 11 is provided between the first sealing layer portion 9 and the second sealing layer portion 10 in the thickness direction of the sealing layer 8.

Description

All-solid-state secondary battery

[0001] The present invention relates to an all-solid-state secondary battery.

[0002] Lithium-ion secondary batteries are essential for mobile devices, electric vehicles, and other devices, and have established themselves as high-capacity, lightweight power sources. However, current lithium-ion secondary batteries primarily use flammable organic electrolytes, raising concerns about the risk of fire. To address this issue, development is underway on all-solid-state secondary batteries, such as all-solid-state lithium-ion secondary batteries and all-solid-state sodium-ion secondary batteries, which use solid electrolytes instead of organic electrolytes.

[0003] Patent Document 1 listed below discloses an all-solid-state secondary battery produced by bonding, with a thermosetting resin, the end face of a folded seal portion to the side face of an electrode body of an all-solid-state battery element enclosed in a laminate exterior body made of a laminate core material and a laminate sealing material.

[0004] JP 2015-79719 A

[0005] However, as in Patent Document 1, all-solid-state secondary batteries sealed with a resin material have a problem in that they are difficult to use in high-temperature environments. Furthermore, in all-solid-state secondary batteries, a short circuit may occur between the positive electrode current collector and the negative electrode current collector. In particular, when an all-solid-state secondary battery is operated at a high temperature of 250° C. or higher, a short circuit is likely to occur between the positive electrode current collector and the negative electrode current collector.

[0006] An object of the present invention is to provide an all-solid-state secondary battery in which a short circuit is unlikely to occur between a positive electrode current collector and a negative electrode current collector.

[0007] Hereinafter, various aspects of all-solid-state secondary batteries that solve the above problems will be described.

[0008] An all-solid-state secondary battery according to a first aspect of the present invention includes: an energy storage element having a solid electrolyte layer, a positive electrode layer, and a negative electrode layer; a first current collector layer provided on one main surface of the energy storage element; a second current collector layer provided on the other main surface of the energy storage element; and a sealing layer provided between the first current collector layer and the second current collector layer to seal the energy storage element, wherein the sealing layer has a first sealing layer portion, a second sealing layer portion, and an insulating layer portion having a volume resistivity higher than that of the first sealing layer portion and the second sealing layer portion, and the insulating layer portion is provided between the first sealing layer portion and the second sealing layer portion in a thickness direction of the sealing layer.

[0009] The all-solid-state secondary battery according to Aspect 2 is the same as Aspect 1, and preferably, the first sealing layer portion and the second sealing layer portion contain glass having a softening point of 500° C. or less.

[0010] The all-solid-state secondary battery according to Aspect 3 is the battery of Aspect 2, wherein the first sealing layer portion and the second sealing layer portion are made of Bi ２ O ３ -B ２ O ３ It is preferable that the glass contains a glass-based material.

[0011] An all-solid-state secondary battery according to Aspect 4 is any one of Aspects 1 to 3, wherein an absolute value of a difference in thermal expansion coefficient in a temperature range of 30° C. to 300° C. between the material constituting the first sealing layer portion and the material constituting the first current collector layer and between the material constituting the second sealing layer portion and the material constituting the second current collector layer is 2.0×10 －６ / K or less is preferable.

[0012] An all-solid-state secondary battery according to Aspect 5 is any one of Aspects 1 to 4, wherein an absolute value of a difference in thermal expansion coefficient between a material constituting the first sealing layer portion and the second sealing layer portion and a material constituting the insulating layer portion in a temperature range of 30° C. to 300° C. is 2.0×10 －６ / K or less is preferable.

[0013] In the all-solid-state secondary battery according to Aspect 6, in any one of Aspects 1 to 5, it is preferable that the material constituting the insulating layer portion is at least one of ceramic and glass.

[0014] A seventh aspect of the all-solid-state secondary battery is the battery of any one of the first to sixth aspects, wherein the volume resistivity of the insulating layer portion at 350° C. is 10 ５ It is preferably Ω·cm or more.

[0015] According to the present invention, it is possible to provide an all-solid-state secondary battery in which a short circuit is unlikely to occur between the positive electrode current collector and the negative electrode current collector.

[0016] FIG. 1 is a schematic plan view showing an all-solid-state secondary battery according to a first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a portion along line A-A in FIG. 1. FIG. 3 is a schematic cross-sectional view showing an all-solid-state secondary battery according to a second embodiment of the present invention. FIG. 4 is a schematic cross-sectional view showing an all-solid-state secondary battery according to a third embodiment of the present invention. FIG. 5 is a schematic cross-sectional view showing an all-solid-state secondary battery according to a fourth embodiment of the present invention. FIG. 6 is a schematic cross-sectional view showing an all-solid-state secondary battery according to a fifth embodiment of the present invention.

[0017] Preferred embodiments of the present invention 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 each drawing, components having substantially the same functions may be referred to by the same reference numerals.

[0018] [First embodiment] Fig. 1 is a schematic plan view showing an all-solid-state secondary battery according to a first embodiment of the present invention, and Fig. 2 is a schematic cross-sectional view showing a portion along line AA in Fig. 1.

[0019] 1 and 2 , the all-solid-state secondary battery 1 includes a power storage element 2, a first current collector layer 6, a second current collector layer 7, and a sealing layer 8. Examples of the all-solid-state secondary battery 1 include an all-solid-state lithium-ion secondary battery, an all-solid-state sodium-ion secondary battery, or an all-solid-state magnesium-ion secondary battery. While an all-solid-state sodium-ion secondary battery will be described below as an example, the following embodiment is applicable to all-solid-state secondary batteries in general.

[0020] The energy storage element 2 has a first main surface 2 a and a second main surface 2 b facing each other. A first current collector layer 6 is provided on the first main surface 2 a of the energy storage element 2. A second current collector layer 7 is provided on the second main surface 2 b of the energy storage element 2.

[0021] In this embodiment, the energy storage element 2 has a solid electrolyte layer 3, a positive electrode layer 4, and a negative electrode layer 5. In the energy storage element 2, the negative electrode layer 5, the solid electrolyte layer 3, and the positive electrode layer 4 are stacked in this order. The positive electrode layer 4 is provided on the first main surface 2a side of the energy storage element 2. The negative electrode layer 5 is provided on the second main surface 2b side of the energy storage element 2.

[0022] In this embodiment, the solid electrolyte layer 3 is made of a sodium ion conductive oxide and has a first main surface 3a and a second main surface 3b that face each other.

[0023] A positive electrode layer 4 is provided on a first main surface 3 a of the solid electrolyte layer 3. In this embodiment, the positive electrode layer 4 contains a positive electrode active material capable of absorbing and desorbing sodium. A first current collector layer 6 is provided on the main surface of the positive electrode layer 4 opposite to the side on which the solid electrolyte layer 3 is disposed.

[0024] An anode layer 5 is provided on the second main surface 3b of the solid electrolyte layer 3. In this embodiment, the anode layer 5 contains an anode active material capable of absorbing and releasing sodium. A second current collector layer 7 is provided on the main surface of the anode layer 5 opposite to the side on which the solid electrolyte layer 3 is disposed.

[0025] A sealing layer 8 is provided between the outer peripheral portion 6 a of the first current collector layer 6 and the outer peripheral portion 7 a of the second current collector layer 7. The sealing layer 8, together with the first current collector layer 6 and the second current collector layer 7, forms an internal space 1 a. The energy storage element 2 is disposed in and sealed within this internal space 1 a. In this embodiment, the sealing layer 8 has a frame-like shape. However, the shape of the sealing layer 8 is not particularly limited as long as it can form the internal space 1 a together with the first current collector layer 6 and the second current collector layer 7 and seal the energy storage element 2.

[0026] The sealing layer 8 has a first sealing layer portion 9, a second sealing layer portion 10, and an insulating layer portion 11. The insulating layer portion 11 has a higher volume resistivity than the first sealing layer portion 9 and the second sealing layer portion 10. In addition, in the sealing layer 8, the second sealing layer portion 10, the insulating layer portion 11, and the first sealing layer portion 9 are stacked in this order. Therefore, in the thickness direction of the sealing layer 8, the insulating layer portion 11 is provided between the first sealing layer portion 9 and the second sealing layer portion 10.

[0027] The all-solid-state secondary battery 1 of this embodiment has the above-described configuration, and therefore is less likely to cause a short circuit between the positive electrode side current collector (first current collector layer 6) and the negative electrode side current collector (second current collector layer 7).

[0028] In conventional all-solid-state secondary batteries, a short circuit may occur between a positive electrode current collector and a negative electrode current collector, particularly when the all-solid-state secondary battery is operated at a high temperature of 250° C. or higher.

[0029] In response to this, the inventors focused on sealing layer 8 provided between first current collector layer 6 and second current collector layer 7, and discovered that the above problem can be solved by using sealing layer 8 in which insulating layer portion 11 with high volume resistivity is provided between first sealing layer portion 9 and second sealing layer portion 10 in particular.

[0030] In general, glass used as a sealing layer material can be used at higher temperatures than resin. However, conventionally used sealing layer materials tend to have lower volume resistivity as the temperature increases. Therefore, when an all-solid-state secondary battery is operated at high temperatures, a short circuit may occur between the positive electrode current collector and the negative electrode current collector through the sealing layer, which has a lower volume resistivity.

[0031] Therefore, it is desirable that the insulating layer portion 11 constituting the sealing layer 8 has a large volume resistivity at high temperatures. Specifically, the volume resistivity of the insulating layer portion 11 at 350° C. is preferably 10 ５ Ω cm or more, more preferably 10 ６ Ω cm or more, more preferably 10 ７ Ω cm or more, preferably 10１５ Ω·cm or less. When the volume resistivity of the insulating layer portion 11 at 350°C is equal to or greater than the above lower limit, even when the all-solid-state secondary battery 1 is operated at high temperatures, it is possible to make it difficult for a short circuit to occur between the first current collector layer 6 on the positive electrode side and the second current collector layer 7 on the negative electrode side. The volume resistivity of the insulating layer portion 11 at 350°C is not particularly limited, but can be set to, for example, the above upper limit or less due to the properties of the material. On the other hand, the volume resistivity of the first sealing layer portion 9 and the second sealing layer portion 10 at 350°C is not particularly limited, and can be, for example, 10 Ω·cm or more, 9.9×10 ４ It is possible to make it Ω·cm or less.

[0032] In this specification, the volume resistivity of each material can be measured by, for example, four-terminal DC resistance measurement or the double ring electrode method.

[0033] The material constituting the insulating layer portion 11 is preferably at least one of ceramic and glass. As the ceramic, for example, zirconia, forsterite, steatite, alumina, etc. can be used. As the glass, for example, a material having a thermal expansion coefficient of 8.0×10 in the temperature range of 30°C to 300°C can be used. －６ / K or more, 20.0×10 －６ / K or less, and the thermal expansion coefficient in the temperature range of 30°C to 300°C is 8.0 x 10 －６ / K or more, 25.0×10 －６ More specifically, the glass may be soda lime glass, SiO ２ -BaO-based glass, SiO ２ -SrO-based glass, SiO ２ -MgO-based glass, SiO ２ -CaO-based glass, etc., or SiO ２ -BaO-based, SiO ２ -SrO-based, SiO ２ -MgO-based, SiO ２ -Ceramic glass such as CaO can be used.

[0034] The thickness of the insulating layer portion 11 is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more, and is preferably 20 mm or less, more preferably 15 mm or less, even more preferably 10 mm or less, still more preferably 5 mm or less, even more preferably 3 mm or less, still more preferably 2 mm or less, and particularly preferably 1 mm or less. When the thickness of the insulating layer portion 11 is equal to or greater than the above-mentioned lower limit, a short circuit between the first current collector layer 6 on the positive electrode side and the second current collector layer 7 on the negative electrode side can be made even less likely to occur. On the other hand, when the thickness of the insulating layer portion 11 is equal to or less than the above-mentioned upper limit, the first current collector layer 6 and the second current collector layer 7 can be bonded even more reliably.

[0035] It is desirable that the first sealing layer portion 9 and the second sealing layer portion 10 are made of the same material. The material for the first sealing layer portion 9 and the second sealing layer portion 10 can be, for example, glass. The softening point of the glass is not particularly limited, but is preferably 300°C or higher, more preferably 350°C or higher, even more preferably 400°C or higher, and is preferably 600°C or lower, more preferably 550°C or lower, and even more preferably 500°C or lower. When the softening point of the glass is above the above lower limit, the all-solid-state secondary battery 1 can be used more stably at high temperatures. Furthermore, when the softening point of the glass is below the above upper limit, the thermal stability and chemical stability of the glass can be further improved, making it easier to handle as a powder or paste.

[0036] The glass used for the first sealing layer portion 9 and the second sealing layer portion 10 is not particularly limited, but for example, Bi ２ O ３ -B ２ O ３ Bismuth-based glass such as Bi-based glass can be used. Bismuth-based glass has a glass composition of, in mol %, Bi ２ O ３ 25% to 60%, B ２ O ３ It is preferable that the content of CuO+MnO is 10% to 35%, and CuO+MnO is 1% to 40%.

[0037] When the material of the first current collector layer 6 and the second current collector layer 7 is aluminum, the glass used for the first sealing layer portion 9 and the second sealing layer portion 10 may be, for example, tellurium-based glass. The tellurium-based glass has a glass composition of, in mol %, TeO ２ 15% to 80%, MoO ３ + Ag ２ O 0.1% to 30%, V ２ O ５ It is preferable that the content of SiO2 is 5% to 40% and that of CuO is 0.1% to 35%.

[0038] In the present embodiment, the thickness of insulating layer portion 11 is preferably greater than the thickness of first sealing layer portion 9 or the thickness of second sealing layer portion 10 (thickness of the sealing layer portion). In this case, it is possible to make it even less likely that a short circuit will occur between first current collector layer 6 on the positive electrode side and second current collector layer 7 on the negative electrode side. Note that in the present invention, the thickness of insulating layer portion 11 may be smaller than the thickness of first sealing layer portion 9 or the thickness of second sealing layer portion 10 (thickness of the sealing layer portion), and is not particularly limited.

[0039] In the present embodiment, the ratio of the thickness of the insulating layer portion 11 to the thickness of the sealing layer portion (insulating layer portion 11 / sealing layer portion) is preferably 0.001 or more, more preferably 0.01 or more, even more preferably 0.1 or more, and is preferably 1000 or less, more preferably 100 or less, and even more preferably 10 or less. When the thickness ratio (insulating layer portion 11 / sealing layer portion) is equal to or greater than the above-mentioned lower limit, it is possible to further reduce the likelihood of a short circuit occurring between the first current collector layer 6 on the positive electrode side and the second current collector layer 7 on the negative electrode side. When the thickness ratio (insulating layer portion 11 / sealing layer portion) is equal to or less than the above-mentioned upper limit, it is possible to further reliably bond the first current collector layer 6 and the second current collector layer 7.

[0040] The thicknesses of first sealing layer portion 9 and second sealing layer portion 10 are each preferably 1 μm or more, more preferably 10 μm or more, and even more preferably 100 μm or more, and preferably 100 mm or less, more preferably 10 mm or less, and even more preferably 1 mm or less. When the thicknesses of first sealing layer portion 9 and second sealing layer portion 10 are equal to or greater than the above-mentioned lower limit, first current collector layer 6 and second current collector layer 7 can be more reliably bonded to each other. On the other hand, when the thicknesses of first sealing layer portion 9 and second sealing layer portion 10 are equal to or less than the above-mentioned upper limit, thermal strain resulting from the difference in thermal expansion coefficients between sealing layer 8, first current collector layer 6, and second current collector layer 7 can be further reduced, and bonding strength can be further increased.

[0041] In the present embodiment, the width of insulating layer portion 11 is preferably larger than the widths of first sealing layer portion 9 and second sealing layer portion 10. In this case, it is possible to further reduce the likelihood of a short circuit occurring between first current collector layer 6 on the positive electrode side and second current collector layer 7 on the negative electrode side. Note that in the present invention, the width of insulating layer portion 11 may be smaller than the widths of first sealing layer portion 9 and second sealing layer portion 10, and is not particularly limited.

[0042] In the present embodiment, the ratio of the width of insulating layer portion 11 to the width of each of first sealing layer portion 9 and second sealing layer portion 10 (insulating layer portion 11 / first sealing layer portion 9 or second sealing layer portion 10) is preferably 0.5 or more, more preferably 0.75 or more, even more preferably 1.0 or more, and is preferably 100 or less, more preferably 10 or less, and even more preferably 5 or less. When the width ratio (insulating layer portion 11 / first sealing layer portion 9 or second sealing layer portion 10) is equal to or greater than the above-mentioned lower limit, it is possible to further reduce the likelihood of a short circuit occurring between the first current collector layer 6 on the positive electrode side and the second current collector layer 7 on the negative electrode side. When the width ratio (insulating layer portion 11 / first sealing layer portion 9 or second sealing layer portion 10) is equal to or less than the above-mentioned upper limit, it is possible to further reliably bond the first current collector layer 6 and the second current collector layer 7.

[0043] The width of the insulating layer portion 11 is not particularly limited, but is preferably 500 μm or more, more preferably 1000 μm or more, and even more preferably 1500 μm or more, and is preferably 500 mm or less, more preferably 250 mm or less, and even more preferably 100 mm or less. When the width of the insulating layer portion 11 is equal to or greater than the above-mentioned lower limit, it is possible to further reduce the likelihood of a short circuit occurring between the first current collector layer 6 on the positive electrode side and the second current collector layer 7 on the negative electrode side. On the other hand, when the width of the insulating layer portion 11 is equal to or less than the above-mentioned upper limit, it is possible to more reliably bond the first current collector layer 6 and the second current collector layer 7.

[0044] The widths of the first sealing layer portion 9 and the second sealing layer portion 10 are not particularly limited, but are preferably 10 μm or more, more preferably 100 μm or more, and even more preferably 1000 μm or more, and are preferably 500 mm or less, more preferably 100 mm or less, and even more preferably 10 mm or less. When the widths of the first sealing layer portion 9 and the second sealing layer portion 10 are equal to or greater than the above-mentioned lower limit, the airtightness of the internal space 1 a can be more reliably maintained, and leakage from the internal space 1 a can be more reliably prevented. On the other hand, when the widths of the first sealing layer portion 9 and the second sealing layer portion 10 are equal to or less than the above-mentioned upper limit, thermal strain resulting from the difference in thermal expansion coefficient between the first sealing layer portion 9 and the second sealing layer portion 10 and the first current collector layer 6 and the second current collector layer 7 can be further reduced, and the bonding strength can be further increased.

[0045] The absolute value of the difference in thermal expansion coefficient between the material constituting first sealing layer portion 9 and second sealing layer portion 10 and the material constituting first current collector layer 6 and second current collector layer 7 in the temperature range of 30°C to 300°C is preferably 2.0 × 10 －６ / K or less, more preferably 1.0 × 10 －６ / K or less, more preferably 0.5 × 10 －６ / K or less. In this case, the adhesion between the sealing layer 8 and at least one of the first current collector layer 6 and the second current collector layer 7 can be further improved. Therefore, it is desirable that the materials constituting the first current collector layer 6 and the second current collector layer 7 both satisfy the above-mentioned range of the absolute value of the difference in thermal expansion coefficient. Furthermore, it is preferable that the thermal expansion coefficient of the material constituting the sealing layer 8 in the temperature range of 30°C to 300°C is smaller than the thermal expansion coefficient of the material constituting at least one of the first current collector layer 6 and the second current collector layer 7 in the temperature range of 30°C to 300°C. In this way, the bonding strength of the sealing layer 8 can be increased.

[0046] The absolute value of the difference in thermal expansion coefficient between the material constituting the first sealing layer portion 9 and the second sealing layer portion 10 and the material constituting the insulating layer portion 11 in the temperature range of 30°C to 300°C is preferably 2.0 x 10 －６ / K or less, more preferably 1.0 × 10 －６ / K or less, more preferably 0.5 × 10 －６ In this case, the adhesion between the first sealing layer portion 9 and the second sealing layer portion 10 and the insulating layer portion 11 can be further improved.

[0047] The thermal expansion coefficient of each material can be measured in the temperature range of 30°C to 300°C using, for example, a thermomechanical analyzer (TMA).

[0048] In this embodiment, the internal space 1a of the all-solid-state secondary battery 1 is hollow. As described above, the internal space 1a of the all-solid-state secondary battery 1 is preferably hollow, but the internal space 1a may be filled with an inorganic porous body. The inorganic porous body is preferably an insulating material. Examples of the inorganic porous body that can be used include glass wool, rock wool, ceramic fiber, alkaline earth silicate fiber, and porous ceramic body.

[0049] In this embodiment, the internal space 1a of the all-solid-state secondary battery 1 is a vacuum. The internal space 1a of the all-solid-state secondary battery 1 may be filled with an inert gas or a mixed gas of a reducing gas and an inert gas. Examples of the inert gas that can be used include rare gas, nitrogen gas, and carbon dioxide gas, and these inert gases can also be mixed. Of these, the inert gas is preferably a rare gas. In this case, more stable battery characteristics can be obtained in the all-solid-state secondary battery 1. Examples of rare gases include helium, neon, and argon, and these rare gases can also be mixed. Of these, argon is preferably used as the rare gas. Examples of the mixed gas of a reducing gas and an inert gas that can be used include a mixed gas of hydrogen gas and nitrogen gas.

[0050] Pressure P outside the all-solid-state secondary battery 1 at 25°C ２ and the pressure P １ The difference between ２ -P １ ) is preferably 10 －６ The difference (P ２ -P １ ) is equal to or greater than the lower limit, the first current collector layer 6 and the second current collector layer 7 can be elastically deformed toward the internal space 1 a, and the current collector layers can be brought into more reliable contact with the electrode layers. Therefore, in this case, the all-solid-state secondary battery 1 can achieve even more stable battery characteristics.

[0051] Hereinafter, each layer constituting the all-solid-state secondary battery 1 will be described in detail.

[0052] (Solid Electrolyte Layer) The solid electrolyte layer 3 can be formed of an ion-conductive material such as a sodium ion-conductive oxide. Examples of sodium ion-conductive oxides include compounds containing at least one element selected from Al, Y, Zr, Si, and P, Na, and O. Specific examples of sodium ion-conductive oxides include beta-alumina and NASICON crystals, which have excellent sodium ion conductivity. Of these, beta-alumina is preferred as the sodium ion-conductive oxide from the viewpoint of achieving even better sodium ion conductivity.

[0053] Beta alumina includes β-alumina (theoretical composition formula: Na ２ O.11Al ２ O ３ ) and β″-alumina (theoretical composition formula: Na ２ O 5.3 Al ２ O ３ β"-alumina is a metastable material, so it is usually ２ The beta-alumina is preferably made of β"-alumina alone or a mixture of β"-alumina and β-alumina, since β"-alumina has a higher sodium ion conductivity than β-alumina. １．４９ Li ０．２５ Al １０．７５ O １７ , Na １．７ Li ０．３ Al １０．７ O １７ , Na １．７２ Li ０．３ Al １０．６６ O １７ , Na １．６ Li ０．３４ Al １０．６６ O １７ Li etc. ２ O-stabilized β″-alumina or (Al １０．３２ Mg ０．６８ O １６ ) (Na １．６８ O), (Al １０．３５ Mg ０．６５ O １６ ) (Na １．６５O), (Al ８．８７ Mg ２．１３ O １６ ) (Na ３．１３ O), Na １．６７ Mg ０．６７ Al １０．３３ O １７ It is more preferable to use MgO-stabilized β″-alumina such as

[0054] NASICON crystals include Na ３ Zr ２ Si ２ P.O. １２ , Na ３．２ Zr １．３ Si ２．２ P ０．７ O １０．５ , Na ３ Zr １．６ Ti ０．４ Si ２ P.O. １２ , Na ３ Hf ２ Si ２ P.O. １２ , Na ３．４ Zr ０．９ Hf １．４ Al ０．６ Si １．２ P １．８ O １２ , Na ３ Zr １．７ Nb ０．２４ Si ２ P.O. １２ , Na ３．６ Ti ０．２ Y ０．８ Si ２．８ O ９ , Na ３ Zr １．８８ Y ０．１２ Si ２ P.O. １２ , Na ３．１２ Zr １．８８ Y ０．１２ Si ２ P.O. １２ , Na ３．０５ Zr ２ Si ２．０６ P ０．９５ O １２ , Na ３．４ Zr ２ Si ２．４ P０．６ O １２ 、No ３．４ Zr １．９ Zn ０．１ Yes ２．４ P ０．６ O １２ 、No ３．４ Zr １．９ Mg ０．１ Yes ２．４ P ０．６ O １２ 、No ３．４ Zr １．９ Zn ０．１ Yes ２．２ P ０．８ O １２ 、No ３．４ Zr １．９ Mg ０．１ Yes ２．２ P ０．８ O １２ 、No ２．８ Zr ２ Yes ２．４ P ０．６ O １２ 、No ５ YSi ４ O １２ 、No ３．１ Zr １．９５ Mg ０．０５ Yes ２ PO １２ 、No ３．１ Zr １．９ Yes ０．１ Yes ２ PO １２ 、No ３．１ Zr １．９ N$ ０．１ Yes ２ PO １２ 、No ３．１ Zr １．９ Y ０．１ Yes ２ PO １２ 、No ３．２５６ Zr １．８７２ Mg ０．１２８ Yes ２ PO １２ 、No ３．２ Zr １．９ Ca ０．１ Yes ２ PO １２ 、No ３．２ Zr １．９ Mg ０．１Si ２ PO １２ 、Na ３．２ Zr ２ Si ２．２ P ０．８ O １２ 、Na ３．３８ Zr １．８０ Al ０．２６ Si ２．０６ P ０．８８ O １２ 、Na ３．４３ Zr １．８３ Zhậu ０．２２ Si １．９３ P １．０２ O １２ 、Na ３．４ Sc ０．４ Zr １．６ Si ２ PO １２ 、Na ３．４ Zr １．８ Mẽ ０．２ Si ２ PO １２ 、Na ３．４ Zr １．９ Zhậu ０．１ Si ２．２ P ０．８ O １２ 、Na ３．５７ Zr １．７２ Lẽ ０．２１ Si ２．０８ P ０．９２ O １２ 、Na ３ Zr １．９８ N｡ ０．０８ Si ２ PO １２ 、Na ３ Zr １．９ Yes ０．１ Si ２ PO １２ 、Na ３ Zr １．９ G$ ０．１ Si ２ PO １２ 、Na ３ Zr １．９ Ti ０．１ Si ２ PO １２ 、Na ３ Zr １．９ Yb ０．１ Si ２ PO １２ 、 or３．６ Zr ０．１３ Yb １．６７ Si ０．１１ P ２．９ O １２ From the viewpoint of superior sodium ion conductivity, Na ３．１２ Zr １．８８ Y ０．１２ Si ２ P.O. １２ , Na ３．４ Zr ２ Si ２．４ P ０．６ O １２ , Na ３．４ Zr １．９ Zn ０．１ Si ２．４ P ０．６ O １２ , Na ３．４ Zr １．９ Mg ０．１ Si ２．４ P ０．６ O １２ , Na ３．４ Zr １．９ Zn ０．１ Si ２．２ P ０．８ O １２ , Na ３．４ Zr １．９ Mg ０．１ Si ２．２ P ０．８ O １２ , Na ３．４３ Zr １．８３ Zn ０．２２ Si １．９３ P １．０２ O １２ , Na ３．４ Sc ０．４ Zr １．６ Si ２ P.O. １２ , Na ３．４ Zr １．８ Mg ０．２ Si ２ P.O. １２ , or Na ３．４ Zr １．９ Zn ０．１ Si ２．２ P ０．８ O １２ It is preferable to use

[0055] The solid electrolyte layer 3 can be produced by mixing raw material powders, molding the mixed raw material powders, and then firing the molded product. For example, the solid electrolyte layer 3 can be produced by forming a green sheet from the raw material powders into a slurry, and then firing the green sheet. The solid electrolyte layer 3 may also be produced by a sol-gel method.

[0056] The thickness of the solid electrolyte layer 3 is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and preferably 1000 μm or less, more preferably 200 μm or less, and even more preferably 100 μm or less. When the thickness of the solid electrolyte layer 3 is equal to or greater than the above-mentioned lower limit, the mechanical strength of the all-solid-state secondary battery 1 can be further increased, making it less susceptible to breakage and internal short circuits. When the thickness of the solid electrolyte layer 3 is equal to or less than the above-mentioned upper limit, the internal resistance can be further reduced, making it possible to further improve the capacity and operating voltage of the all-solid-state secondary battery 1. Also, the energy density per unit volume of the all-solid-state secondary battery 1 can be further improved.

[0057] (Positive Electrode Layer) The positive electrode active material contained in the positive electrode layer 4 is not particularly limited, but for example, ｘ M ｙ P ２ O ｚ (1≦x≦2.8, 0.95≦y≦1.6, 6.5≦z≦8, M is at least one element selected from the group consisting of Fe, Ni, Co, Mn, and Cr) can be used as a positive electrode active material. ｘ MP ２ O ７ (1≦x≦2, M is at least one selected from the group consisting of Fe, Ni, Co, Mn, and Cr), or ４ M ３ (P.O. ４ ) ２ (P ２ O ７) (M is at least one selected from the group consisting of Fe, Ni, Co, Mn, and Cr). ２ FeP ２ O ７ , Na ２ CoP ２ O ７ , Na ２ NiP ２ O ７ , Na ４ Fe ３ (P.O. ４ ) ２ (P ２ O ７ ) etc. can be used.

[0058] In this specification, crystallized glass refers to the precursor glass containing amorphous phase that is heated (fired) to precipitate crystals (crystallization).In crystallized glass, all of the amorphous phase may be transformed into crystalline phase, or amorphous phase may remain.In addition, in crystallized glass, one type of crystal may be precipitated, or two or more types of crystal may be precipitated.For example, it is possible to determine whether crystallized glass is crystallized glass by the peak angle shown by powder X-ray diffraction (XRD).

[0059] The positive electrode layer 4 may contain a sodium ion conductive solid electrolyte and a conductive additive in addition to the positive electrode active material. The positive electrode layer 4 may contain, for example, by mass %, 60% to 99.9% of the positive electrode active material, 0% to 30% of the sodium ion conductive solid electrolyte, and 0.1% to 10% of the conductive additive.

[0060] The sodium ion conductive solid electrolyte may be, for example, one of those described in the section on the solid electrolyte layer 3. The conductive additive may be, for example, conductive carbon. Examples of conductive carbon include acetylene black, carbon black, ketjen black, vapor grown carbon fiber (VGCF), and carbon nanotubes.

[0061] The positive electrode layer 4 can be formed, for example, by forming an electrode material layer on the first main surface 3 a of the solid electrolyte layer 3 and firing the electrode material layer. The electrode material layer can be obtained, for example, by applying a paste containing a positive electrode active material precursor and, if necessary, a solid electrolyte powder and a conductive additive, and then drying the paste. The paste may contain, if necessary, a binder, a plasticizer, a solvent, or the like. The electrode material layer may be a powder compact.

[0062] The thickness of the positive electrode layer 4 is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more, and is preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 200 μm or less. When the thickness of the positive electrode layer 4 is equal to or greater than the above-mentioned lower limit, the capacity of the all-solid-state secondary battery 1 can be further improved. When the thickness of the positive electrode layer 4 is equal to or less than the upper limit, the capacity and operating voltage of the all-solid-state secondary battery 1 can be further improved, and the positive electrode layer 4 is less likely to shrink due to firing when the positive electrode layer 4 is formed, and the positive electrode layer 4 can be made less likely to peel off.

[0063] A metal thin film may be provided on the main surface of the positive electrode layer 4 facing the first current collector layer 6. In this case, the electronic conductivity at the interface between the positive electrode layer 4 and the first current collector layer 6 can be further increased. Examples of the metal thin film include an aluminum film. The metal thin film can be formed by, for example, a sputtering method or a vacuum deposition method. In particular, from the viewpoint of increasing the adhesion between the positive electrode layer 4 and the first current collector layer 6, the metal thin film is preferably a sputtered film formed by a sputtering method.

[0064] (Negative Electrode Layer) The negative electrode active material contained in the negative electrode layer 5 is not particularly limited, and may be, for example, a carbon electrode material such as hard carbon or soft carbon. The carbon electrode material is preferably hard carbon. However, the negative electrode active material may be an alloy-based negative electrode active material capable of absorbing sodium, such as tin, bismuth, lead, or phosphorus, or may contain metallic sodium. The negative electrode active material may also be an oxide-based negative electrode active material capable of absorbing sodium, such as anatase-type titanium oxide, rutile-type titanium oxide, or brookite-type titanium oxide. It is preferable that the negative electrode layer 5 is not a negative electrode layer consisting of a single phase of metallic sodium.

[0065] The negative electrode layer 5 may contain, in addition to the negative electrode active material, a sodium ion conductive solid electrolyte and a conductive additive. The negative electrode layer 5 may contain, for example, by mass %, 60% to 95% of the negative electrode active material, 5% to 35% of the sodium ion conductive solid electrolyte, and 0% to 5% of the conductive additive.

[0066] The sodium ion conductive solid electrolyte may be, for example, one described in the section on the solid electrolyte layer 3. The conductive additive may be, for example, one described in the section on the positive electrode layer 4.

[0067] The negative electrode layer 5 can be formed, for example, by forming an electrode material layer on the second main surface 3b of the solid electrolyte layer 3 and firing the electrode material layer. The electrode material layer can be obtained, for example, by applying and drying a paste containing a carbon electrode material precursor (a precursor of a carbon electrode material made of hard carbon) and, as necessary, a sodium ion conductive solid electrolyte and a conductive additive. The paste may contain, as necessary, a binder, a plasticizer, a solvent, or the like. The electrode material layer may be a compact.

[0068] The thickness of the anode layer 5 is preferably 3 μm or more, more preferably 7 μm or more, and even more preferably 10 μm or more, and is preferably 300 μm or less, more preferably 200 μm or less, and even more preferably 100 μm or less. When the thickness of the anode layer 5 is equal to or greater than the above-mentioned lower limit, deposition of sodium metal in the anode layer 5 during charging of the all-solid-state secondary battery 1 can be suppressed, and the cycle performance of the all-solid-state secondary battery 1 can be improved. When the thickness of the anode layer 5 is equal to or less than the upper limit, the capacity and operating voltage of the all-solid-state secondary battery 1 can be further improved.

[0069] A metal thin film may be provided on the main surface of the negative electrode layer 5 facing the second current collector layer 7. In this case, the electronic conductivity at the interface between the negative electrode layer 5 and the second current collector layer 7 can be further improved. An example of the metal thin film is an aluminum film. The metal thin film can be formed by, for example, a sputtering method or a vacuum deposition method. In particular, from the viewpoint of improving the adhesion between the negative electrode layer 5 and the second current collector layer 7, the metal thin film is preferably a sputtered film formed by a sputtering method.

[0070] (First current collector layer and second current collector layer) The materials for the first current collector layer 6 and the second current collector layer 7 are not particularly limited, and metal materials such as aluminum, titanium, silver, copper, stainless steel (SUS), or alloys thereof can be used, respectively. These metal materials may be used alone or in combination. The above alloy refers to an alloy containing at least one of the above metals.

[0071] The thickness of each of the first current collector layer 6 and the second current collector layer 7 is preferably 20 μm or more, more preferably 30 μm or more, and even more preferably 40 μm or more, and is preferably 2000 μm or less, more preferably 1000 μm or less, and even more preferably 500 μm or less. When the thickness of the first current collector layer 6 and the second current collector layer 7 is within the above range, the current collecting function as a current collector can be further improved.

[0072] In plan view, the outer peripheral edges of the first current collector layer 6 and the second current collector layer 7 are disposed outside the outer peripheral edge of the energy storage element 2. The protrusion width of the first current collector layer 6 and the second current collector layer 7 from the solid electrolyte layer 3 is preferably 0.1 mm or more, more preferably 0.2 mm or more, and is preferably 3 mm or less, more preferably 2 mm or less.

[0073] A method for manufacturing the all-solid-state secondary battery 1 will be described below.

[0074] (Method for manufacturing all-solid-state secondary battery) First, an energy storage element 2 is prepared. At this time, a single energy storage element 2 may be prepared, or a stack of a plurality of energy storage elements 2 may be prepared. Note that, hereinafter, both of the above cases will be referred to as the energy storage element 2.

[0075] Next, a paste for forming sealing layer portions is prepared for forming the first sealing layer portion 9 and the second sealing layer portion 10. The paste for forming sealing layer portions can be prepared, for example, by the following method.

[0076] First, raw material powders prepared to obtain a desired glass composition are melted until a homogeneous glass is obtained. The melting temperature can be, for example, 700° C. or higher and 1000° C. or lower. The melting time can be, for example, 1 hour or higher and 2 hours or lower.

[0077] Next, the obtained molten glass is formed into a film or the like, and then crushed and classified to produce glass powder. ５０ The average particle size can be 1 μm or more and 20 μm or less. Alternatively, a refractory filler powder may be mixed with the glass powder to form the sealing material. In this case, the thermal expansion coefficient of the sealing material can be adjusted to be close to the thermal expansion coefficients of the first current collector layer 6 and the second current collector layer 7. Furthermore, the mechanical strength of the resulting sealing layer 8 can be further increased. The refractory filler powder can be added within a range that does not impair the fluidity of the glass powder. For example, the amount of the refractory filler powder added can be 40 volume % or less of the entire sealing material.

[0078] The refractory filler constituting the refractory filler powder is not particularly limited, and examples thereof include zircon, zirconia, tin oxide, quartz, β-spodumene, cordierite, willemite, mullite, quartz glass, β-eucryptite, β-quartz, zirconium phosphate, zirconium tungstate phosphate, zirconium tungstate, NbZr(PO ４ ) ３ [AB ２ (MO ４ ) ３

[0033] (wherein A is Li, Na, K, Mg, Ca, Sr, Ba, Zn, Cu, Ni, Mn, etc.; B is Zr, Ti, Sn, Nb, Al, Sc, Y, etc.; M is P, Si, W, Mo, etc.), or a solid solution thereof can be used. Among these, the refractory filler is preferably zirconium phosphate, cordierite, willemite, or zirconium tungstate phosphate. These refractory fillers have a low thermal expansion coefficient, and therefore can further increase the mechanical strength. In addition, Bi ２ O ３ -B ２ O ３ It also has excellent compatibility with glass.

[0079] Next, a vehicle is added to the sealing material and kneaded to obtain a paste for forming the sealing layer portion. Here, the vehicle mainly consists of an organic solvent and a resin. The resin can be added to adjust the viscosity of the paste. If the softening point of the sealing material is low and problems arise with the degreasing process, a high-viscosity organic solvent that does not contain a resin can also be used. If necessary, a surfactant, a thickener, or the like can also be added to the vehicle. Before kneading the glass powder or refractory filler powder with the vehicle, the glass powder or refractory filler powder may be subjected to vacuum treatment for a certain period of time at a temperature near the glass transition point of the glass powder in order to remove traces of moisture or organic matter adhering to the surface of the glass powder or refractory filler powder.

[0080] The organic solvent is preferably one that has a low boiling point and leaves little residue after firing. It is also preferable that the organic solvent does not alter the glass. The content of the organic solvent can be, for example, 10% by mass or more and 40% by mass or less, based on the total amount of the vehicle.

[0081] Examples of the organic solvent include propylene carbonate, toluene, N,N'-dimethylformamide (DMF), 1,3-dimethyl-2-imidazolidinone (DMI), dimethyl carbonate, butyl carbitol acetate (BCA), isoamyl acetate, dimethyl sulfoxide, acetone, and methyl ethyl ketone. The organic solvent is preferably a higher alcohol. Higher alcohols have viscosity in themselves, so they can be made into a paste without adding a resin to the vehicle. From the viewpoint of excellent viscosity, the organic solvent is preferably pentanediol or diethylpentanediol (C ９ H ２０ O ２ ) and other pentanediol derivatives.

[0082] The resin preferably has a low decomposition temperature, leaves little residue after firing, and is resistant to alteration of the glass. The resin content can be 0.1% by mass or more and 20% by mass or less based on the total mass of the vehicle. Examples of resins that can be used include nitrocellulose, polyethylene glycol derivatives, polyethylene carbonate, and acrylic esters (acrylic resins).

[0083] Next, the prepared sealing layer portion forming paste is applied to the first current collector layer 6 and the second current collector layer 7. Specifically, the sealing layer portion forming paste is applied to the outer peripheral edge portion 6a of the first current collector layer 6 so as to form a frame shape. Furthermore, the sealing layer portion forming paste is applied to the outer peripheral edge portion 7a of the second current collector layer 7 so as to form a frame shape.

[0084] The application of the sealing layer portion forming paste to the first current collector layer 6 and the second current collector layer 7 can be performed using, for example, an applicator such as a dispenser or a screen printer. It is desirable to make the surface roughness of the application area of ​​the sealing layer portion forming paste (the area where the sealing layer 8 is formed) rougher than that of other areas. In this case, the adhesion between the resulting sealing layer 8 and the first current collector layer 6 and the second current collector layer 7 can be further improved. Examples of methods for increasing the surface roughness of the application area of ​​the sealing layer portion forming paste include etching with hydrochloric acid or blasting such as wet blasting. The surface roughness of the application area of ​​the sealing layer portion forming paste can be, for example, 0.5 μm or more and 5 μm or less in terms of arithmetic mean roughness Ra.

[0085] Before applying the sealing layer portion forming paste, tab leads may be previously joined to the first current collector layer 6 and the second current collector layer 7 by welding, soldering, etc. The tab leads may be made of aluminum, nickel, stainless steel (SUS), etc.

[0086] If the tab lead is made of a material that is difficult to solder, such as SUS430, a metal layer may be formed on the surface of the tab lead before welding it to the tab. Examples of the metal layer include copper (Cu), gold (Au), silver (Ag), palladium (Pd), tin (Sn), zinc (Zn), cobalt (Co), nickel (Ni), a Ni-Cu alloy, or a Ni-P alloy. These materials may be used alone or in combination.

[0087] Next, the sealing layer portion forming paste applied to the first current collector layer 6 and the second current collector layer 7 is pre-fired. The pre-fired temperature can be, for example, 200° C. or higher and 500° C. or lower. The pre-fired time can be, for example, 5 minutes or higher and 300 minutes or lower. Note that, before pre-firing, the sealing layer portion forming paste may be dried in advance to dry out the organic solvent contained in the sealing layer portion forming paste.

[0088] Next, the insulating layer portion 11 is prepared. The insulating layer portion 11 is obtained, for example, by cutting a plate made of at least one of the aforementioned ceramic and glass materials into a frame-like shape similar to that of the sealing layer portion-forming paste applied to the first current collector layer 6 and the second current collector layer 7. The ceramic plate is formed, for example, by mixing ceramic and a binder and causing a solid-phase reaction. The glass plate is formed, for example, by a melt-quenching method.

[0089] Next, the energy storage element 2 is mounted on the second current collector layer 7. Next, the insulating layer portion 11 is superimposed on the sealing layer portion-forming paste of the second current collector layer 7. Next, the first current collector layer 6 is superimposed on the second current collector layer 7 with the insulating layer portion 11 superimposed thereon, and bonded to it. When superimposing the first current collector layer 6 on the second current collector layer 7 with the insulating layer portion 11 superimposed thereon, the superimposition is performed so that the insulating layer portion 11 is sandwiched between the surfaces coated with the sealing layer portion-forming paste of each layer.

[0090] The first current collector layer 6 and the second current collector layer 7 can be bonded by firing the sealing layer portion-forming paste. The sealing layer 8 can be formed by firing the sealing layer portion-forming paste. The firing temperature of the sealing layer portion-forming paste is preferably 300°C or higher, more preferably 350°C or higher, and even more preferably 400°C or higher, and is preferably 700°C or lower, more preferably 600°C or lower, and even more preferably 500°C or lower. The firing time of the sealing layer portion-forming paste can be, for example, 10 minutes or longer and 300 minutes or shorter. The sealing layer portion-forming paste is desirably fired in an inert atmosphere or a vacuum atmosphere.

[0091] The area where sealing layer 8 is to be formed may be covered in advance with a highly heat-resistant adhesive. In this case, it is possible to further increase the adhesion between the resulting sealing layer 8 and the first and second current collector layers 6 and 7. Examples of highly heat-resistant adhesives include polyimide, polyimide amide, epoxy resin, silicone resin, and fluorine-based resins such as polytetrafluoroethylene (PTFE).

[0092] In the all-solid-state secondary battery 1 obtained by the manufacturing method of this embodiment, the insulating layer portion 11 having a higher volume resistivity than the first sealing layer portion 9 and the second sealing layer portion 10 is provided between the first sealing layer portion 9 and the second sealing layer portion 10 in the sealing layer 8. This makes it possible to make a short circuit less likely to occur between the positive electrode side current collector (first current collector layer 6) and the negative electrode side current collector (second current collector layer 7).

[0093] [Second and Third Embodiments] Fig. 3 is a schematic cross-sectional view showing an all-solid-state secondary battery according to a second embodiment of the present invention, and Fig. 4 is a schematic cross-sectional view showing an all-solid-state secondary battery according to a third embodiment of the present invention.

[0094] As shown in Fig. 3, in the all-solid-state secondary battery 21 of the second embodiment, the second current collector layer 27 has a container-like shape. An energy storage element 22 is mounted inside this container-like second current collector layer 27. In the energy storage element 22, a positive electrode layer is provided on the first current collector layer 6 side, and a negative electrode layer is provided on the second current collector layer 27 side. A sealing layer 8 is provided on the upper surface of the container-like second current collector layer 27 and is joined to the flat plate-like first current collector layer 6. An insulating layer may be provided on the inner surface of the side wall of the container-like second current collector layer 27. The other points are the same as those of the first embodiment.

[0095] As shown in FIG. 4 , in an all-solid-state secondary battery 31 of the third embodiment, a second current collector layer 37 is drawn into a rectangular tube shape. An energy storage element 32 is mounted inside the second current collector layer 37 drawn into this rectangular tube shape. In the energy storage element 32, a positive electrode layer is provided on the first current collector layer 6 side, and a negative electrode layer is provided on the second current collector layer 37 side. A sealing layer 8 is provided on the upper surface of the second current collector layer 37 drawn into a rectangular tube shape, and is joined to the flat first current collector layer 6. An insulating layer may be provided on the inner surface of the sidewall of the second current collector layer 37 drawn into a rectangular tube shape. Other points are the same as those of the first embodiment.

[0096] In the second and third embodiments, an insulating layer portion having a higher volume resistivity than the first sealing layer portion and the second sealing layer portion is provided between the first sealing layer portion and the second sealing layer portion in sealing layer 8. This makes it possible to reduce the likelihood of a short circuit occurring between the positive electrode side current collector (first current collector layer 6) and the negative electrode side current collector (second current collector layer 27, 37).

[0097] Fourth Embodiment FIG. 5 is a schematic cross-sectional view showing an all-solid-state secondary battery according to a fourth embodiment of the present invention.

[0098] As shown in Fig. 5, in an all-solid-state secondary battery 41 of the fourth embodiment, a spacer pin 42 is provided between the first current collector layer 6 and the second current collector layer 7 in the internal space 1a. The shape of the spacer pin 42 is not particularly limited, and examples thereof include a cylindrical shape, a rectangular pillar shape, and a hollow cylinder. Examples of the spacer pin 42 include a ceramic pin. Examples of the material of the ceramic pin include alumina, zirconia, and yttria-stabilized zirconia. Other points are the same as those of the first embodiment.

[0099] As in the fourth embodiment, spacer pins 42 may be provided between the first current collector layer 6 and the second current collector layer 7. By providing the spacer pins 42, the distance between the first current collector layer 6 and the second current collector layer 7 can be maintained more reliably.

[0100] Fifth Embodiment FIG. 6 is a schematic cross-sectional view showing an all-solid-state secondary battery according to a fifth embodiment of the present invention.

[0101] 6 , in an all-solid-state secondary battery 51 of the fifth embodiment, a through-hole 52 is provided in the first current collector layer 6. The through-hole 52 is provided as an exhaust port for evacuating the internal space 1 a in the manufacturing process of the all-solid-state secondary battery 51. The through-hole 52 may also be provided in the second current collector layer 7. The position of the through-hole 52 is not particularly limited as long as it allows the internal space 1 a to be evacuated.

[0102] The diameter of the through holes 52 is preferably 0.1 μm or more, more preferably 1 μm or more, and even more preferably 10 μm or more, and is preferably 10 mm or less, more preferably 5 mm or less, and even more preferably 1 mm or less. When the diameter of the through holes 52 is equal to or greater than the above-mentioned lower limit, the interior space 1 a can be more reliably decompressed and evacuated through the through holes 52. When the diameter of the through holes 52 is equal to or less than the above-mentioned upper limit, the current collecting function of the first current collector layer 6 can be more effectively exhibited.

[0103] In this embodiment, the through-holes 52 are sealed with a sealing material. This forms a sealing portion 53 in the first current collector layer 6. In this embodiment, the sealing material forming the sealing portion 53 contains glass. When the sealing material contains glass, as in this embodiment, the all-solid-state secondary battery 51 can be used more stably in a high-temperature environment (for example, about 200°C). Note that the sealing material forming the sealing portion 53 is not particularly limited as long as it can seal the through-holes 52. The other points are the same as those in the first embodiment.

[0104] As in the fifth embodiment, the first current collector layer 6 may have a through hole 52. In this case, after the sealing layer 8 is formed, the internal space 1 a can be evacuated via the through hole 52, and then the through hole 52 can be sealed. Therefore, the sealing layer 8 does not need to be formed in an evacuated state, and therefore the material of the sealing layer 8 is less likely to foam, and the resulting sealing layer 8 is less likely to become a foam. Therefore, the strength of the sealing layer 8 is less likely to decrease, and the strength of the package that seals the energy storage element 2 is also less likely to decrease. Therefore, the all-solid-state secondary battery 51 of the fifth embodiment can further improve reliability.

[0105] DESCRIPTION OF SYMBOLS 1, 21, 31, 41, 51... all-solid-state secondary battery 1a... internal space 2, 22, 32... energy storage element 2a, 3a... first main surface 2b, 3b... second main surface 3... solid electrolyte layer 4... positive electrode layer 5... negative electrode layer 6... first current collector layer 6a, 7a... outer peripheral edge portion 7, 27, 37... second current collector layer 8... sealing layer 9... first sealing layer portion 10... second sealing layer portion 11... insulating layer portion 42... spacer pin 52... through hole 53... sealing portion

Claims

1. An all-solid-state secondary battery comprising: an energy storage element having a solid electrolyte layer, a positive electrode layer, and a negative electrode layer; a first current collector layer provided on one main surface of the energy storage element; a second current collector layer provided on the other main surface of the energy storage element; and a sealing layer provided between the first current collector layer and the second current collector layer and sealing the energy storage element, wherein the sealing layer has a first sealing layer portion, a second sealing layer portion, and an insulating layer portion having a volume resistivity higher than that of the first sealing layer portion and the second sealing layer portion, and the insulating layer portion is provided between the first sealing layer portion and the second sealing layer portion in the thickness direction of the sealing layer.

2. The all-solid-state secondary battery according to claim 1, wherein the first sealing layer portion and the second sealing layer portion contain glass having a softening point of 500°C or less.

3. The first sealing layer portion and the second sealing layer portion are made of Bi. ２ O ３ -B ２ O ３ The all-solid-state secondary battery according to claim 2 , comprising a glass-based material.

4. The absolute value of the difference in thermal expansion coefficient between the material constituting the first sealing layer portion and the material constituting the first current collector layer, and between the material constituting the second sealing layer portion and the material constituting the second current collector layer, in the temperature range of 30°C to 300°C is 2.0 x 10 －６ The all-solid-state secondary battery according to claim 1 or 2, wherein the solubility is 0.1 / K or less.

5. The absolute value of the difference in thermal expansion coefficient between the material constituting the first sealing layer portion and the second sealing layer portion and the material constituting the insulating layer portion in the temperature range of 30°C to 300°C is 2.0 x 10 －６ The all-solid-state secondary battery according to claim 1 or 2, wherein the solubility is 0.1 / K or less.

6. The all-solid-state secondary battery according to claim 1 or 2, wherein the material constituting the insulating layer portion is at least one of ceramic and glass.

7. The volume resistivity of the insulating layer at 350°C is 10 ５ The all-solid-state secondary battery according to claim 1 or 2, having a specific resistance of Ω·cm or more.

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