Lithium metal rechargeable battery

Abstract

To provide a lithium metal secondary battery having an intermediate layer between a negative electrode layer and a solid electrolyte layer, wherein lithium metal can be uniformly deposited on the intermediate layer side surface of the negative electrode layer, and the lithium metal secondary battery has a novel structure that is less prone to dendrite formation. [Solution] A lithium metal secondary battery comprising a positive electrode layer, a negative electrode layer, a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, and an intermediate layer disposed between the negative electrode layer and the solid electrolyte layer, wherein a lithium metal layer is disposed on the surface of the negative electrode layer on the intermediate layer side, and an intermediate layer insulating material covers the outer surface of the intermediate layer, and the intermediate layer insulating material does not have lithium ion conductivity.

Description

[Technical Field]

[0001] This invention relates to a lithium metal secondary battery. [Background technology]

[0002] In recent years, research and development has been conducted on rechargeable batteries that contribute to energy efficiency, in order to ensure that more people have access to affordable, reliable, sustainable, and advanced energy. Among rechargeable batteries, lithium metal batteries, which have a high energy density, are attracting attention.

[0003] As an example of a lithium metal secondary battery, a stacked lithium metal secondary battery is known, which comprises a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive and negative electrode layers. Furthermore, the provision of an intermediate layer between the negative electrode layer and the solid electrolyte layer is being considered.

[0004] Patent Document 1 describes that a layer (intermediate layer) with a higher affinity for metallic lithium than the solid electrolyte layer may be provided between the solid electrolyte layer and the negative electrode current collector. Patent Document 2 discloses a technique for suppressing the formation of a high-resistance layer at the interface of the solid electrolyte layer on the positive electrode side by interposing an intermediate layer between the positive electrode layer and the solid electrolyte layer. Furthermore, Patent Document 3 discloses a technique for a lithium metal secondary battery having an intermediate layer, in which at least one surface of the outer circumferential surface of the intermediate layer along the stacking direction is covered with a protective layer that does not have electronic conductivity but has ionic conductivity. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-062572 [Patent Document 2] Japanese Patent Publication No. 2011-044368 [Patent Document 3] Japanese Patent Publication No. 2024-031684 [Overview of the project] [Problems that the invention aims to solve]

[0006] Incidentally, in lithium metal secondary batteries having an intermediate layer between the negative electrode layer and the solid electrolyte layer, it is preferable to uniformly deposit lithium metal on the intermediate layer side of the negative electrode layer during charging, thereby making it difficult for dendrites to form. In the lithium metal secondary battery disclosed in Patent Document 3, the outer surface of the intermediate layer is covered with a protective layer that does not have electronic conductivity but has ion conductivity, thereby inducing lithium ions into the protective layer and suppressing the deposition of lithium metal on the outer surface of the intermediate layer. This uniformly deposits lithium metal on the intermediate layer side of the negative electrode layer, making it difficult for dendrites to form. However, it is desirable to uniformly deposit lithium metal on the intermediate layer side of the negative electrode layer without inducing lithium ions into the solid electrolyte layer or protective layers other than the intermediate layer, thereby making it difficult for dendrites to form.

[0007] The present invention aims to provide a lithium metal secondary battery having an intermediate layer between a negative electrode layer and a solid electrolyte layer, which allows for uniform deposition of lithium metal on the intermediate layer side of the negative electrode layer and provides a novel structure that is less prone to dendrite formation. This will ultimately contribute to improved energy efficiency. [Means for solving the problem]

[0008] The inventors have discovered that in a lithium metal secondary battery having an intermediate layer between the negative electrode layer and the solid electrolyte layer, by covering the outer surface of the intermediate layer with an intermediate layer insulating material that does not conduct lithium ions, lithium metal can be uniformly deposited on the intermediate layer side of the negative electrode layer, making dendrite formation less likely, and thus completing the present invention. Accordingly, the present invention provides the following.

[0009] (1) A lithium metal secondary battery comprising a positive electrode layer, a negative electrode layer, a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, and an intermediate layer disposed between the negative electrode layer and the solid electrolyte layer, wherein a lithium metal layer is disposed on the surface of the negative electrode layer on the intermediate layer side, and an intermediate layer insulating material covers the outer surface of the intermediate layer, and the intermediate layer insulating material does not have lithium ion conductivity.

[0010] In the lithium metal secondary battery of (1), lithium is easily deposited on the surface of the intermediate layer of the negative electrode layer because a lithium metal layer is arranged therein. Also, since the intermediate layer insulating material covering the outer surface of the intermediate layer does not conduct lithium ions, it is unlikely that lithium ions will move through the intermediate layer insulating material, and electrons e - The supply can be reliably shut off. Furthermore, since the outer surface of the intermediate layer is covered with an intermediate layer insulating material, powder shedding of the intermediate layer is less likely to occur. As a result, it is less likely that the intermediate layer will be lost due to powder shedding, causing the solid electrolyte layer and the negative electrode layer to come into direct contact. Therefore, according to the lithium metal secondary battery 1 of this embodiment, lithium ions move stably between the solid electrolyte layer and the negative electrode layer via the intermediate layer, so that lithium metal can be uniformly deposited on the surface of the lithium metal layer of the negative electrode layer, and dendrite formation is less likely to occur.

[0011] (2) In a top view, the outer edge of the intermediate insulating layer overlaps with the outer edge of the solid electrolyte layer and is located outside the outer edge of the lithium metal layer, as described in (1).

[0012] In the lithium metal secondary battery described in (2), even if the solid electrolyte layer deforms toward the negative electrode layer, an intermediate insulating material is present between the solid electrolyte layer and the lithium metal layer, making it difficult for the solid electrolyte layer and the lithium metal layer to come into contact.

[0013] (3) The lithium metal secondary battery according to (1), wherein, in a top view, the outer edge of the intermediate layer insulating material, the outer edge of the solid electrolyte layer, and the outer edge of the lithium metal layer overlap each other.

[0014] According to the lithium metal secondary battery of (3), when the solid electrolyte layer is deformed to the negative electrode layer side, the lithium metal layer is similarly deformed, so that it becomes difficult for the solid electrolyte layer and the lithium metal layer to come into contact with each other.

[0015] (4) In a top view, the outer edge of the intermediate layer is inside the outer edge of the solid electrolyte layer and inside the outer edge of the lithium metal layer, and the lithium metal secondary battery according to any one of (1) to (3).

[0016] According to the lithium metal secondary battery of (4), the lithium ions that have moved through the intermediate layer are less likely to move to the outer peripheral side of the lithium metal layer, and it becomes difficult for lithium to precipitate on the outer periphery of the lithium metal layer. Therefore, lithium metal can be deposited more uniformly on the surface of the lithium metal layer on the intermediate layer side, and dendrites are less likely to occur.

[0017] (5) The positive electrode layer has a positive electrode active material layer. In a top view, the outer edge of the positive electrode active material layer is inside the outer edge of the intermediate layer, the outer edge of the intermediate layer overlaps with the outer edge of the lithium metal layer or is inside the outer edge of the lithium metal layer, and the outer edge of the lithium metal layer is inside the intermediate layer insulating material. The lithium metal secondary battery according to (1).

[0018] According to the lithium metal secondary battery of (5), since the surface distance between the positive electrode active material layer and the lithium metal layer becomes long, it becomes difficult for the positive electrode layer and the negative electrode layer to short-circuit.

[0019] (6) The intermediate layer insulating material is made of alumina, and the lithium metal secondary battery according to any one of (1) to (5).

[0020] According to the lithium metal secondary battery of (6), since the intermediate layer insulating material is made of alumina, it is less likely for lithium ions to move through the intermediate layer insulating material, and the supply of electrons e - can be more reliably blocked.

Advantages of the Invention

[0021] According to the present invention, it is possible to provide a lithium metal secondary battery having an intermediate layer in which lithium metal can be uniformly deposited on the surface of the intermediate layer on the negative electrode layer, and a novel structure in which dendrites are less likely to form. [Brief explanation of the drawing]

[0022] [Figure 1] This is a plan view showing the configuration of a lithium metal secondary battery according to the first embodiment. [Figure 2] This is a cross-sectional view taken along line II-II in Figure 1. [Figure 3] This is a cross-sectional view taken along line III-III in Figure 1. [Figure 4] This is a cross-sectional view showing the manufacturing process of a lithium metal secondary battery according to the first embodiment. [Figure 5] This is a cross-sectional view showing the configuration of a lithium metal secondary battery according to the second embodiment. [Figure 6] This is a cross-sectional view showing the manufacturing process of a lithium metal secondary battery according to the second embodiment. [Modes for carrying out the invention]

[0023] <First Embodiment> A lithium metal secondary battery according to the first embodiment of the present invention will be described with reference to Figures 1 to 3. Figure 1 is a plan view showing the configuration of the lithium metal secondary battery according to the first embodiment. Figure 2 is a cross-sectional view taken along line II-II of Figure 1, and is a cross-sectional view taken in a direction along the extension direction of the positive electrode current collector 11 and the negative electrode current collector 21 of the lithium metal secondary battery 1. Figure 3 is a cross-sectional view taken along line III-III of Figure 1, and is a cross-sectional view taken in a direction perpendicular to the extension direction of the positive electrode current collector 11 and the negative electrode current collector 21 of the lithium metal secondary battery 1.

[0024] The lithium metal secondary battery 1 according to this embodiment is a stacked lithium metal secondary battery 1 comprising a positive electrode layer 10, a negative electrode layer 20, a solid electrolyte layer 30 disposed between the positive electrode layer 10 and the negative electrode layer 20, and an intermediate layer disposed between the negative electrode layer 20 and the solid electrolyte layer 30. The positive electrode layer 10 and the negative electrode layer 20 extend in directions opposite to each other. The positive electrode layer 10 has a positive electrode current collector 11 and a positive electrode active material layer 12 disposed on the solid electrolyte layer 30 side of the positive electrode current collector 11. The outer circumferential surface of the positive electrode active material layer 12 is covered with a positive electrode active material layer insulating frame 13. The negative electrode layer 20 has a negative electrode current collector 21 and a lithium metal layer 22 disposed on the surface of the negative electrode current collector 21 on the intermediate layer 40 side.

[0025] The lithium metal secondary battery 1 further includes an intermediate layer insulating material 41 that covers the outer surface of the intermediate layer 40. The intermediate layer insulating material 41 does not have electronic conductivity and does not have lithium ion conductivity. "Does not have electronic conductivity" means that its electronic conductivity is 10⁻¹⁰. -6 This means that the conductivity is less than or equal to S / m. "Not having lithium-ion conductivity" means that lithium ions do not conduct during charging and discharging of the lithium metal secondary battery 1. The lithium-ion conductivity of the intermediate layer insulating material 41 is lower than that of the intermediate layer 40.

[0026] In this embodiment, the lithium metal secondary battery 1 deposits lithium metal on the surface of the lithium metal layer 22 during charging, and the deposited lithium metal is released and moves to the positive electrode active material layer 12 during discharging. As a result, the lithium metal secondary battery 1 experiences a large change in the thickness of the negative electrode layer 20 due to charging and discharging. The change in the thickness of the negative electrode layer 20 due to charging and discharging applies pressure to the intermediate layer 40, which can cause powder shedding, where a portion of the outer surface of the intermediate layer 40 falls off. Furthermore, during the manufacturing of the lithium metal secondary battery 1, powder shedding may occur in a portion of the intermediate layer 40 due to the pressure applied when pressing the intermediate layer 40 to the solid electrolyte layer 30 or when pressing the intermediate layer 40 to the lithium metal layer 22. The intermediate layer insulating material 41 has the effect of suppressing powder shedding of the intermediate layer 40. It is preferable that the intermediate layer insulating material 41 covers the entire outer surface of the intermediate layer 40. By covering the entire outer surface of the intermediate layer 40 with the intermediate layer insulating material 41, the effect of suppressing powder shedding of the intermediate layer 40 is further enhanced.

[0027] In a top view of the lithium metal secondary battery 1 of this embodiment, the outer edges of each layer are located as follows. The outer edge refers to the end of the plane perpendicular to the stacking direction of the lithium metal secondary battery 1.

[0028] The outer edge of the solid electrolyte layer 30 is outside the outer edge of the lithium metal layer 22. The outer edge of the intermediate insulating layer 41 overlaps with the outer edge of the solid electrolyte layer 30.

[0029] The outer edge of the intermediate layer 40 is outside the outer edge of the positive electrode active material layer 12. However, the outer edge of the intermediate layer 40 may overlap with the outer edge of the positive electrode active material layer 12. The outer edge of the intermediate layer 40 is inside the outer edge of the solid electrolyte layer 30. The outer edge of the intermediate layer 40 is inside the outer edge of the lithium metal layer 22.

[0030] The outer edge of the positive electrode active material layer 12 is located inside the outer edge of the intermediate layer 40. However, the outer edge of the positive electrode active material layer 12 may overlap with the outer edge of the intermediate layer 40. The outer edge of the positive electrode active material layer 12 is located inside the outer edge of the lithium metal layer 22.

[0031] The outer edge of the positive electrode active material layer insulating frame 13 is outside the outer edge of the solid electrolyte layer 30 in the extending direction of the positive electrode current collector 11 and the negative electrode current collector 21. In a direction perpendicular to the extending direction of the positive electrode current collector 11 and the negative electrode current collector 21, the outer edge of the positive electrode active material layer insulating frame 13 overlaps with the outer edge of the solid electrolyte layer 30. However, even in a direction perpendicular to the extending direction of the positive electrode current collector 11 and the negative electrode current collector 21, the outer edge of the positive electrode active material layer insulating frame 13 may be outside the outer edge of the solid electrolyte layer 30.

[0032] In the lithium metal secondary battery 1, examples of the material of the positive electrode current collector 11 include aluminum, aluminum alloy, stainless steel, nickel, iron, and titanium.

[0033] The positive electrode active material layer 12 contains a positive electrode active material. The positive electrode active material is a lithium compound that releases lithium ions during discharge and occludes lithium ions during charging. As the lithium compound, for example, a layered active material, a spinel-type active material, and an olivine-type active material can be used. Specific examples of the positive electrode active material include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium nickel manganese cobalt oxide (NMC: LiNi p Mn q Co r O2 (p + q + r = 1)), LiNi p Al q Co r O2 (p + q + r = 1), lithium manganate (LiMn2O4), Li 1+x Mn 2-x-y MO4 (x + y = 2, M = at least one selected from Al, Mg, Co, Fe, Ni, and Zn) represented by a hetero-element substituted Li-Mn spinel, lithium titanate (an oxide containing Li and Ti), lithium metal phosphate (LiMPO4, M = at least one selected from Fe, Mn, Co, and Ni), etc. The positive electrode active material layer 12 may further contain a conductive assistant and a binder.

[0034] The positive electrode active material layer insulating frame 13 is not particularly limited as long as it has electronic insulating properties. The positive electrode active material layer insulating frame 13 may or may not have lithium ion conductivity. Examples of materials for the positive electrode active material layer insulating frame 13 include insulating oxides such as alumina, resins such as polyvinylidene fluoride (PVDF), and rubbers such as styrene-butadiene rubber (SBR).

[0035] Examples of materials for the negative electrode current collector 21 include copper, copper alloys, nickel, and stainless steel.

[0036] The lithium metal layer 22 can be any material that deposits lithium ions during charging. The material for the lithium metal layer 22 can be lithium or a metal that forms an alloy with lithium. Examples of metals that form alloys with lithium include Mg, Si, Au, Ag, In, Ge, Sn, Pb, Al, and Zn.

[0037] The solid electrolyte layer 30 contains a solid electrolyte. Examples of solid electrolytes include sulfide solid electrolytes, oxide solid electrolytes, nitride solid electrolytes, and halide solid electrolytes. Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-P2S5-LiI, etc. The sulfide solid electrolyte may have an argyrodite crystal structure. Examples of oxide solid electrolytes include NASICON type oxides, garnet type oxides, and perovskite type oxides. Examples of NASICON type oxides include oxides containing Li, Al, Ti, P, and O (e.g., Li 1.5 Al 0.5 Ti 1.5 (PO4)3) is an example. Examples of garnet-type oxides include oxides containing Li, La, Zr, and O (e.g., Li7La3Zr2O) 12 Examples of perovskite-type oxides include those containing Li, La, Ti, and O (e.g., LiLaTiO3). The solid electrolyte layer 30 may contain a binder in addition to the solid electrolyte material.

[0038] The intermediate layer 40 may be a layer having voids through which lithium ions can pass. By allowing lithium ions to pass through the intermediate layer 40, lithium metal can be uniformly deposited on the surface of the lithium metal layer 22. Furthermore, because the intermediate layer 40 has voids and is flexible, it can follow the changes in the thickness of the lithium metal secondary battery 1 that occur during charging and discharging.

[0039] The material of the intermediate layer 40 is not particularly limited, but the intermediate layer 40 includes, for example, amorphous carbon, metal nanoparticles, and a binder. The amorphous carbon may be easily graphitizable carbon (soft carbon), poorly graphitizable carbon (hard carbon), CNT (carbon nanotube), fullerene, or graphene. Examples of amorphous carbon include carbon blacks such as acetylene black, furnace black, and Ketjen black, as well as coke and activated carbon. Examples of metal nanoparticles include tin (Sn), silicon (Si), zinc (Zn), magnesium (Mg), gold (Au), platinum (Pt), palladium (Pd), silver (Ag), aluminum (Al), bismuth (Bi), and antimony (Sb). Examples of binders include acrylic acid polymers, cellulose polymers, styrene polymers, vinyl acetate polymers, urethane polymers, fluoroethylene polymers, and PVDF polymers.

[0040] The material of the intermediate layer insulating material 41 does not need to be electronically conductive or ionically conductive. Examples of materials that can be used for the intermediate layer insulating material 41 include ceramics and resins. Alumina is an example of a ceramic. The ceramic may be a sintered body or, if necessary, a molded body formed using a binder.

[0041] The manufacturing method of the lithium metal secondary battery 1 of this embodiment will be described with reference to Figure 4. Figure 4 is a cross-sectional view showing the manufacturing process of the lithium metal secondary battery according to the first embodiment.

[0042] First, as shown in Figure 4(a), a solid electrolyte layer-intermediate layer laminate is obtained by laminating an intermediate layer 40, on one surface of a solid electrolyte layer 30, with an intermediate layer insulating material 41 arranged on its outer surface. As a method for producing the intermediate layer-solid electrolyte layer laminate, for example, an overcoat method or a transfer method can be used. The overcoat method is a method in which an intermediate layer 40 is formed on the surface of a substrate, then an intermediate layer insulating material 41 is formed along the outer surface of the intermediate layer 40, and then a solid electrolyte layer 30 is formed on the surfaces of the intermediate layer 40 and the intermediate layer insulating material 41. As a method for forming the intermediate layer 40, the intermediate layer insulating material 41 and the solid electrolyte layer 30, a coating method can be used. The coating method is a method in which a material slurry containing the materials that form each layer is applied and dried. The transfer method is a method in which a solid electrolyte layer 30 formed on each separate substrate and an intermediate layer 40 with an intermediate layer insulating material 41 arranged on its outer surface are pressed together.

[0043] Next, as shown in Figure 4(b), the positive electrode layer 10 is pressed onto the surface of the solid electrolyte layer 30 of the solid electrolyte layer-intermediate layer laminate to obtain a positive electrode layer-solid electrolyte layer-intermediate layer laminate. For the positive electrode layer 10, for example, a method can be used in which a positive electrode active material layer 12 is formed on the surface of the positive electrode current collector 11, and then the outer surface of the positive electrode active material layer 12 is covered with a positive electrode active material layer insulating frame 13. A coating method can be used as the method for forming the positive electrode active material layer 12 and the positive electrode active material layer insulating frame 13.

[0044] Next, the lithium metal layer 22 of the negative electrode layer 20 is pressed onto the surface of the intermediate layer 40 of the positive electrode layer-solid electrolyte layer-intermediate layer laminate. In this way, a lithium metal secondary battery 1 is obtained.

[0045] In the lithium metal secondary battery 1 of this embodiment, which has the above configuration, lithium is easily deposited on the surface of the negative electrode layer 20 on the intermediate layer 40 side because the lithium metal layer 22 is arranged thereon. Also, since the intermediate layer insulating material 41 covering the outer surface of the intermediate layer 40 does not have lithium ion conductivity, lithium ions are less likely to move through the intermediate layer insulating material 41, and electrons e -The supply can be reliably shut off. Furthermore, since the outer surface of the intermediate layer 40 is covered with the intermediate layer insulating material 41, powder shedding of the intermediate layer 40 is less likely to occur. As a result, it is less likely that the intermediate layer 40 will be missing and the solid electrolyte layer 30 and the negative electrode layer 20 will come into direct contact. Therefore, according to the lithium metal secondary battery 1 of this embodiment, lithium ions move stably between the solid electrolyte layer 30 and the negative electrode layer 20 via the intermediate layer 40, so that lithium metal can be uniformly deposited on the surface of the lithium metal layer 22 of the negative electrode layer 20, and dendrite formation is less likely to occur.

[0046] In this embodiment, when viewed from above, the outer edge of the intermediate layer insulating material 41 of the lithium metal secondary battery 1 overlaps with the outer edge of the solid electrolyte layer 30 and is located outside the outer edge of the lithium metal layer. Therefore, even if the solid electrolyte layer 30 deforms toward the negative electrode layer 20, the intermediate layer insulating material 41 remains between the solid electrolyte layer 30 and the lithium metal layer 22. As a result, contact between the solid electrolyte layer 30 and the negative electrode layer 20 is less likely.

[0047] In this embodiment, in a top view, the outer edge of the intermediate layer 40 of the lithium metal secondary battery 1 is located inside the outer edge of the solid electrolyte layer 30 and inside the outer edge of the lithium metal layer 22. Therefore, lithium ions that have moved through the intermediate layer 40 are less likely to move towards the outer periphery of the lithium metal layer 22, and lithium is less likely to be deposited on the outer periphery of the lithium metal layer 22. As a result, the lithium metal secondary battery 1 can deposit lithium metal more uniformly on the surface of the lithium metal layer 22 on the intermediate layer 40 side, and dendrites are less likely to form.

[0048] In this embodiment, when viewed from above, the lithium metal secondary battery 1 has the outer edge of the positive electrode active material layer 12 inside the outer edge of the intermediate layer 40, the outer edge of the intermediate layer 40 inside the outer edge of the lithium metal layer 22, and the outer edge of the lithium metal layer 22 inside the intermediate layer insulating material 41. As a result, the creepage distance between the positive electrode current collector 11 and the negative electrode current collector 21 is increased by the thickness of the intermediate layer and by the fact that the outer edge of the intermediate layer 40 is inside the outer edge of the lithium metal layer 22. Therefore, short circuits between the positive electrode layer 10 and the negative electrode layer 20 are less likely to occur.

[0049] In this embodiment, in a top view, the lithium metal secondary battery 1 has the outer edge of the positive electrode active material layer insulating frame 13 located outside the outer edge of the solid electrolyte layer 30 in the direction of extension of the positive electrode current collector 11 and the negative electrode current collector 21. Therefore, contact between the positive electrode current collector 11 and the negative electrode current collector 21 is less likely. As a result, short circuits between the positive electrode layer 10 and the negative electrode layer 20 in the direction of extension of the positive electrode current collector 11 and the negative electrode current collector 21 are less likely to occur.

[0050] In the lithium metal secondary battery 1 of this embodiment, when the intermediate layer insulating material 41 is made of alumina, it is less likely that lithium ions will move through the intermediate layer insulating material 41, and electron e - This makes it possible to more reliably cut off the supply.

[0051] <Second Embodiment> A lithium metal secondary battery according to a second embodiment of the present invention will be described with reference to Figure 5. Figure 5 is a cross-sectional view showing the configuration of the lithium metal secondary battery according to the second embodiment. Figure 5 is a cross-sectional view of the lithium metal secondary battery 1a in a direction perpendicular to the extension direction of the positive electrode current collector 11 and the negative electrode current collector 21.

[0052] As shown in Figure 5, the lithium metal secondary battery 1a has the same configuration as the lithium metal secondary battery 1 of the first embodiment, except that the outer edges of the intermediate layer insulating material 41, the solid electrolyte layer 30, and the lithium metal layer 22 overlap each other. Therefore, the same reference numerals are used and their descriptions are omitted.

[0053] The manufacturing method of the lithium metal secondary battery 1a of this embodiment will be described with reference to Figure 6. Figure 6 is a cross-sectional view showing the manufacturing process of the lithium metal secondary battery according to the second embodiment.

[0054] First, as shown in Figure 6(a), a negative electrode layer 20 is prepared in which a negative electrode current collector 21 and a lithium metal layer 22 are stacked.

[0055] Next, as shown in Figure 7(b), the intermediate layer 40 of the solid electrolyte layer-intermediate layer laminate, which is laminated on the surface of the lithium metal layer 22 of the negative electrode layer 20 and on one surface of the solid electrolyte layer 30 with an intermediate layer insulating material 41 arranged on its outer circumferential surface, is pressed onto the surface of the lithium metal layer 22 of the negative electrode layer 20 to obtain a solid electrolyte layer-intermediate layer-negative electrode layer laminate. The method for manufacturing the solid electrolyte layer-intermediate layer laminate is the same as the method for manufacturing the solid electrolyte layer-intermediate layer laminate in the manufacturing method of the lithium metal secondary battery 1 of the first embodiment.

[0056] Next, the positive electrode active material layer 12 of the positive electrode layer 10 is pressed onto the surface of the intermediate layer 40 of the solid electrolyte layer-intermediate layer-negative electrode layer laminate. In this way, a lithium metal secondary battery 1a is obtained.

[0057] In the lithium metal secondary battery 1a of this embodiment, which has the above configuration, the surface of the negative electrode layer 20 on the intermediate layer 40 side has a lithium metal layer 22 arranged thereon, and the intermediate layer insulating material 41 covers the outer surface of the intermediate layer 40, so the same effects as the lithium metal secondary battery 1 of the first embodiment can be obtained. Furthermore, in the lithium metal secondary battery 1a of this embodiment, the outer edge of the intermediate layer insulating material 41, the outer edge of the solid electrolyte layer 30, and the outer edge of the lithium metal layer 22 overlap each other, so when the solid electrolyte layer 30 deforms toward the negative electrode layer 20 side, the lithium metal layer 22 deforms in the same way. For this reason, the solid electrolyte layer 30 and the lithium metal layer 22 are less likely to come into contact.

[0058] In this embodiment, the outer edges of the solid electrolyte layer 30, the intermediate insulating material 41, and the lithium metal layer 22 are located inside the outer edge of the positive electrode active material layer insulating frame 13, but the outer edges of each layer may overlap with the outer edge of the positive electrode active material layer insulating frame 13.

[0059] Although preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and any modifications and improvements that can achieve the objectives of the present invention are included in the present invention. [Explanation of Symbols]

[0060] 1. 1a Lithium metal secondary battery 10 Positive electrode layer 11 Positive electrode current collector 12 Cathode active material layer 13. Positive electrode active material layer insulating frame 20 Negative electrode layer 21 Negative electrode current collector 22 Lithium metal layer 30 Solid electrolyte layer 40 Middle Class 41 Intermediate layer insulating material

Claims

1. It comprises a positive electrode layer, a negative electrode layer, a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, and an intermediate layer disposed between the negative electrode layer and the solid electrolyte layer. A lithium metal layer is disposed on the surface of the negative electrode layer on the intermediate layer side. The intermediate layer has an intermediate layer insulating material that covers the outer surface of the intermediate layer, The aforementioned intermediate insulating material is a lithium metal secondary battery that does not have lithium ion conductivity.

2. In a top view, the outer edge of the intermediate insulating layer overlaps with the outer edge of the solid electrolyte layer and is located outside the outer edge of the lithium metal layer, as described in claim 1.

3. The lithium metal secondary battery according to claim 1, wherein, in a top view, the outer edge of the intermediate layer insulating material, the outer edge of the solid electrolyte layer, and the outer edge of the lithium metal layer overlap each other.

4. In a top view, the outer edge of the intermediate layer is inside the outer edge of the solid electrolyte layer and inside the outer edge of the lithium metal layer, as described in claim 1.

5. The positive electrode layer has a positive electrode active material layer, In a top view, the outer edge of the positive electrode active material layer is located inside the outer edge of the intermediate layer. The outer edge of the intermediate layer overlaps with the outer edge of the lithium metal layer or is located inside the outer edge of the lithium metal layer. The lithium metal secondary battery according to claim 1, wherein the outer edge of the lithium metal layer is located inside the intermediate layer insulating material.

6. The lithium metal secondary battery according to claim 1, wherein the intermediate layer insulating material is made of alumina.

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