Solid-state battery and method of manufacturing a solid-state battery

Abstract

The present invention relates to a solid-state battery and a method of manufacturing a solid-state battery. A solid-state battery includes: a positive electrode current collector; a positive electrode layer provided on at least one main surface of the positive electrode current collector; an insulating layer provided on the at least one main surface of the positive electrode current collector, adjoining an end portion of the positive electrode layer, and flush with the positive electrode layer; and a solid electrolyte layer provided on the positive electrode layer and the insulating layer and having an end portion located in a position overlapping the insulating layer.

Description

Technical Field

[0001] This disclosure relates to solid-state batteries and methods for manufacturing solid-state batteries. Background Technology

[0002] In recent years, the importance of secondary batteries has increased, and in addition to secondary batteries that contain electrolytes, the development of solid-state batteries using solid electrolytes is also progressing. All-solid-state batteries, as an example of solid-state batteries, are batteries that use a solid electrolyte layer instead of a liquid electrolyte. Because they do not use flammable organic solvents, safety devices can be simplified, resulting in superior manufacturing costs and productivity.

[0003] International patent WO2012-114497 discloses a solid-state battery in which a first electrode layer, a solid electrolyte layer, and a second electrode layer are stacked sequentially. A first insulating layer is disposed on the outer periphery of the first electrode layer. The size of the stacked surface of the first electrode layer with the stacking direction as its normal direction is smaller than that of the solid electrolyte layer. When viewed from the stacking direction, the outer edge of the solid electrolyte layer is located on the outer periphery of the first electrode layer, and the outer edge of the first insulating layer is also located on the outer periphery of the solid electrolyte layer. The first electrode layer, the first insulating layer, and the solid electrolyte layer are arranged such that the outer edge of the first insulating layer and the end of the solid electrolyte layer are in contact with each other. In the solid-state battery disclosed in International Patent WO2012-114497, since the thickness of the first insulating layer is equal to or less than the thickness of the first electrode layer, bending and damage to the solid electrolyte layer can be suppressed.

[0004] Furthermore, Japanese Patent Application Publication No. (JP-A) 2023-107428 discloses a solid-state battery in which a positive electrode layer formed on a positive current collector has an inclined surface tilted towards the positive current collector, and the inclined surface is covered by an ion-conducting layer having a lower Young's modulus than the solid electrolyte layer. According to JP-A2023-107428, even when the positive electrode layer expands and contracts in association with charging and discharging, stress concentration in the corners of the positive electrode layer relative to the solid electrolyte layer can be suppressed. Summary of the Invention

[0005] However, there is a concern that, for example, if pressure is applied in the stacking direction to a structure in which the positive electrode layer and the solid electrolyte layer are sequentially stacked on the positive electrode current collector, the solid electrolyte layer will eventually continue to deteriorate. Therefore, the object of embodiments of this disclosure is to provide a solid-state battery having a structure in which the positive electrode layer and the solid electrolyte layer are sequentially stacked on the positive electrode current collector, and to prevent damage to the solid electrolyte layer even when pressure is applied in the stacking direction; and a method for manufacturing the solid-state battery.

[0006] The present disclosure, which aims to achieve the above objectives, includes the following aspects.

[0007] <1> A solid-state battery includes: a positive current collector; a positive electrode layer disposed on at least one main surface of the positive current collector; an insulating layer disposed on the at least one main surface of the positive current collector, adjacent to an end of the positive electrode layer, and flush with the positive electrode layer; and a solid electrolyte layer disposed on the positive electrode layer and the insulating layer, with its end located at a position overlapping the insulating layer.

[0008] <2> according to <1> The solid-state battery, wherein the positive current collector includes a positive current collector tab side end connected to the positive current collector tab, and wherein the insulating layer and the positive electrode layer are sequentially disposed from the positive current collector tab side end.

[0009] <3> according to <1> or <2> The solid-state battery includes an adhesive layer between the positive current collector and the positive electrode layer and the insulating layer.

[0010] <4> according to <3> In the solid-state battery, the adhesive layer is conductive.

[0011] <5> according to <3> The solid-state battery, wherein the adhesive layer has a thickness of 0.5 μm to 1.5 μm.

[0012] <6> according to <1> to <5> The solid-state battery according to any one of the following methods further includes a negative electrode layer disposed on the solid electrolyte layer, wherein, in a cross-sectional view along the stacking direction of the positive current collector, the positive electrode layer and the insulating layer, and the solid electrolyte layer, the end of the negative electrode layer is located at a position overlapping the solid electrolyte layer and the insulating layer.

[0013] <7> according to <1> to <6> In any one of the solid-state batteries, in a cross-sectional view along the stacking direction of the positive current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the tilt angle of the end face of the positive electrode layer adjacent to the insulating layer and the tilt angle of the end face of the insulating layer on the opposite side to the end face adjacent to the positive electrode layer are within ±10° relative to the stacking direction.

[0014] <8> A solid-state battery according to any one of <1> to <6>, wherein, in a cross-sectional view along the stacking direction of the positive current collector, the positive electrode layer and the insulating layer, and the solid electrolyte layer, the inclination angle of the end face of the insulating layer opposite to the end face adjacent to the positive electrode layer is closer to 90° than the inclination angle of the end face of the positive electrode layer adjacent to the insulating layer.

[0015] <9> A method for manufacturing a solid-state battery, the method comprising: forming a positive electrode layer and an insulating layer adjacent to and flush with an end of the positive electrode layer on at least one main surface of a positive electrode current collector; and forming a solid electrolyte layer on the positive electrode layer and the insulating layer such that an end of the solid electrolyte layer overlaps with the insulating layer.

[0016] <10> according to <9> The method for manufacturing a solid-state battery further includes forming a negative electrode layer such that, in a cross-sectional view along the stacking direction of the positive current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the end of the negative electrode layer overlaps with the solid electrolyte layer and the insulating layer.

[0017] <11> according to <9> or <10> The method for manufacturing a solid-state battery includes forming an adhesive layer on at least one main surface of the positive electrode current collector when forming the positive electrode layer and the insulating layer, and transferring the positive electrode layer and the insulating layer already formed on the transfer member to the adhesive layer.

[0018] <12> according to <11> In the method for manufacturing a solid-state battery, the adhesive layer is conductive.

[0019] <13> according to <11> The method for manufacturing a solid-state battery, wherein the adhesive layer has a thickness of 0.5 μm to 1.5 μm.

[0020] <14> according to <11> The method for manufacturing a solid-state battery includes coating a positive electrode slurry containing a positive electrode active material onto the transfer member, then cutting off the inclined surface of the peripheral portion of the coated positive electrode slurry, and coating an insulating slurry containing an insulating material to be adjacent to the peripheral portion of the positive electrode slurry, then cutting off the inclined surface of the peripheral portion of the coated insulating slurry.

[0021] <15> according to <14> In the method of manufacturing a solid-state battery, in a cross-sectional view along the stacking direction of the positive current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the tilt angle of the end face of the positive electrode layer adjacent to the insulating layer and the tilt angle of the end face of the insulating layer on the opposite side to the end face adjacent to the positive electrode layer are within ±10° relative to the stacking direction.

[0022] <16> according to <11> The method for manufacturing a solid-state battery includes coating a positive electrode slurry containing a positive electrode active material onto the transfer member, then coating an insulating slurry containing an insulating material to cover the inclined surface of the peripheral portion of the coated positive electrode slurry, and then cutting off the inclined surface of the peripheral portion of the coated insulating slurry.

[0023] <17> according to <16> In the method of manufacturing a solid-state battery, in a cross-sectional view along the stacking direction of the positive current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the inclination angle of the end face of the insulating layer opposite to the end face adjacent to the positive electrode layer is closer to 90° than the inclination angle of the end face of the positive electrode layer adjacent to the insulating layer.

[0024] According to embodiments of this disclosure, even when pressure is applied in the stacking direction to a structure in which the positive electrode layer and the solid electrolyte layer are sequentially stacked on the positive electrode current collector, damage to the solid electrolyte layer can be prevented. Attached Figure Description

[0025] Figure 1 This is a cross-sectional view of the main parts of a solid-state battery described as an embodiment of this disclosure; Figure 2 This is a schematic top view showing an example of a solid-state battery surface being cut by a plane parallel to the stacking direction in a top view viewed from its top surface. Figure 3 This is a cross-sectional view of the main part of a solid-state battery as described in another embodiment of this disclosure; Figures 4A to 4D This is a partial cross-sectional view showing the steps of forming a positive electrode layer and an insulating layer on a transfer component; Figure 5 This is a partial cross-sectional view showing the tilt angle of the end faces of the positive electrode layer and the insulating layer formed on the transfer component; Figure 6 This is a cross-sectional view of the main part of a solid-state battery as described in yet another embodiment of this disclosure; Figures 7A to 7C This is a partial cross-sectional view showing the steps of forming the positive electrode layer and the insulating layer on the transfer component; and Figure 8 This is a partial cross-sectional view showing the tilt angle of the end faces of the positive electrode layer and the insulating layer formed on the transfer component. Detailed Implementation

[0026] In this disclosure, the use of “to” to describe a range of values ​​means that the range includes the values ​​that appear before and after “to” as the minimum and maximum values, respectively.

[0027] Within the numerical ranges described in stages in this disclosure, the upper or lower limit of a given numerical range can be replaced by the upper or lower limit of another numerical range described in stages. Within the numerical ranges described in this disclosure, the upper or lower limit described for a given numerical range can be replaced by the values ​​described in the embodiments.

[0028] In this disclosure, the term "step" includes not only independent steps, but also steps that cannot be clearly distinguished from another step, as long as the intended purpose of the step is achieved.

[0029] In this disclosure, a combination of two or more preferred aspects is a more preferred aspect.

[0030] In this disclosure, when multiple materials are applicable to each component, unless otherwise stated, the amount of each component means the total amount of the multiple materials.

[0031] In this disclosure, when embodiments are described with reference to the accompanying drawings, the configuration of the embodiments is not limited to the configuration shown in the drawings. Furthermore, the dimensions of the components in the drawings are conceptual, and the relative relationships between the dimensions of the components are not limited thereto.

[0032] Solid-state batteries

[0033] The solid-state battery of this disclosure will now be described below. The solid-state battery of this disclosure includes: a positive current collector; a positive electrode layer disposed on at least one main surface of the positive current collector; an insulating layer disposed on the at least one main surface of the positive current collector, adjacent to an end of the positive electrode layer, and flush with the positive electrode layer; and a solid electrolyte layer disposed on the positive electrode layer and the insulating layer, with its end located at a position overlapping the insulating layer. In the solid-state battery of this disclosure, damage to the solid electrolyte layer can be prevented even when pressure is applied in the stacking direction of the positive current collector, the positive electrode layer, and the solid electrolyte layer (e.g., even when subjected to an external force in the stacking direction under a constrained state in which the current collector and the electrode layer are tightly pressed together in the stacking direction).

[0034] like Figure 1 As shown, the solid-state battery described as an embodiment of the present disclosure includes a positive electrode current collector 1, a positive electrode layer 2 and an insulating layer 3 disposed on two main surfaces of the positive electrode current collector 1, a solid electrolyte layer 4 disposed on the positive electrode layer 2 and the insulating layer 3, a negative electrode layer 5 disposed on the solid electrolyte layer 4, a carbon coating 6 disposed on the negative electrode layer 5, and a negative electrode current collector 7 disposed on the carbon coating 6.

[0035] In addition, Figure 1 In the solid-state battery shown, the positive current collector 1 has a positive current collector tab side end 1A connected to the positive current collector tab. The insulating layer 3 and the positive electrode layer 2 are sequentially arranged from the positive current collector tab side end 1A. Figure 1The solid-state battery shown includes an end insulation portion 8 on the end of the positive current collector 1 opposite to the tab side end 1A of the positive current collector. It should be noted that in this disclosure, "stack direction" refers to the direction in which the positive electrode layer 2, the solid electrolyte layer 4, etc., are stacked from the positive current collector 1, such as... Figure 1 As shown by the arrow X in the diagram.

[0036] exist Figure 1 In the solid-state battery shown, the negative electrode layers 5 are each divided into two layers: a first negative electrode layer 5A located on the solid electrolyte layer 4 and a second negative electrode layer 5B located on the first negative electrode layer 5A. However, the negative electrode layers 5 can also be a single layer or have more than two layers. Furthermore, in... Figure 1 In the solid-state battery shown, the negative electrode current collectors 7 are each divided into two layers: a first negative electrode current collector 7A located on the negative electrode layer 5 and a second negative electrode current collector 7B located on the first negative electrode current collector 7A. However, the negative electrode current collectors 7 can also be a single layer or have more than two layers.

[0037] exist Figure 1 In the solid-state battery shown, the positive electrode layer 2 and the insulating layer 3 are formed flush with each other on the main surface of the positive electrode current collector 1. That is, the positive electrode layer 2 and the insulating layer 3 are in contact with each other at one end face, and the main surfaces of the positive electrode layer 2 and the insulating layer 3 form the same plane. Figure 1 In the solid-state battery shown, the end of the solid electrolyte layer 4 on the positive electrode current collector tab side 1A side is located at a position overlapping with the insulating layer 3. That is, the end of the solid electrolyte layer 4 on the positive electrode current collector tab side 1A side is located at a position not overlapping with the positive electrode layer 2, and the solid electrolyte layer 4 is formed to cover the entire surface of the positive electrode layer 2.

[0038] In addition, Figure 1 In the solid-state battery shown, the positive electrode layer 2 is formed by applying a positive electrode slurry to the main surface of the positive current collector 1 and then drying it. Therefore, the end face of the positive electrode layer 2 on the tab side 1A side of the positive current collector becomes an inclined surface due to coating flow. It should be noted that the end face of the positive electrode layer 2 opposite to the tab side 1A side of the positive current collector is cut, so it does not become an inclined surface, but rather a surface in a direction substantially parallel to the stacking direction. Furthermore, in Figure 1 In the solid-state battery shown, after forming the positive electrode layer 2 with an inclined surface, an insulating layer 3 is formed by applying an insulating slurry containing an insulating material and drying it. As a result, the end face of the insulating layer 3 on the positive electrode current collector tab side 1A side becomes an inclined surface due to coating flow. It should be noted that the end face of the insulating layer 3 opposite to the positive electrode current collector tab side 1A side is cut, so it does not become an inclined surface, but rather a surface in a direction substantially parallel to the lamination direction.

[0039] In addition, Figure 1In the solid-state battery shown, the end of the negative electrode layer 5 on the positive electrode current collector tab side 1A is located overlapping the solid electrolyte layer 4 and the insulating layer 3 in a cross-sectional view along the stacking direction X of the positive electrode current collector 1, the positive electrode layer 2, the insulating layer 3, and the solid electrolyte layer 4. "Cross-sectional view along the stacking direction X" refers to the view obtained by cutting the solid-state battery along the stacking direction X of the battery structure, specifically the view observed through the cross-sections passing through the positive electrode current collector tab side end 1A and the ends opposite to the positive electrode current collector tab side end 1A. More specifically, when... Figure 1 When the solid-state battery shown is a prismatic battery, as Figure 2 As shown, the "cross-sectional view along the stacking direction X" can be a cross-sectional view of a section taken along line AA, which, when viewed from above its top surface, roughly bisects the rectangle in its width direction. It should be noted that in Figure 2 In the middle, the AA line, which divides the rectangle into approximately two equal parts in the width direction, passes through the end 1A of the positive current collector tab and the end insulation part 8.

[0040] In the solid-state battery configured as described above, the end face of the solid electrolyte layer 4 disposed on the positive electrode layer 2 is located at a position that overlaps with the insulating layer 3 but not with the positive electrode layer 2. Therefore, even if pressure is applied to the solid-state battery in the stacking direction X, damage to the solid electrolyte layer 4, especially damage to the area near the end face of the solid electrolyte layer 4, can be prevented. Here, "applying pressure in the stacking direction X" means applying pressure in the direction that sandwiches the positive electrode current collector 1, the positive electrode layer 2 and the insulating layer 3, the solid electrolyte layer 4, the negative electrode layer 5, and the negative electrode current collector 7. Although not shown in the figures, the solid-state battery may also include a constraint member that constrains the positive electrode layer 2 and the insulating layer 3, the solid electrolyte layer 4, the negative electrode layer 5, and the negative electrode current collector 7 in the stacking direction. The constraint member applies constraint pressure to the electrode stack in the thickness direction of the electrode stack. For example, the constraint pressure can be equal to or greater than 0.1 MPa, equal to or greater than 1 MPa, or equal to or greater than 5 MPa, and for example equal to or less than 100 MPa, equal to or less than 50 MPa, or equal to or less than 20 MPa. Even when the above pressure is applied by the constraint member, damage to the solid electrolyte layer 4, particularly damage to the area near the end face of the solid electrolyte layer 4, can be prevented in the solid-state battery of this disclosure.

[0041] In addition, Figure 1In the solid-state battery shown, the positive electrode, comprising the positive current collector 1 and the positive electrode layer 2, is located near the center of the electrode stack in the stacking direction X, and the negative electrode, comprising the negative current collector 7 and the negative electrode layer 5, is located on the outer side of the electrode stack in the stacking direction X. In this solid-state battery configuration, the positive electrode layer 2 can be densified by first depositing the positive electrode layer 2 and the insulating layer 3 on the main surface of the positive current collector 1, and then compressing them in the stacking direction. Subsequently, the solid electrolyte layer 4 and the negative electrode layer 5 are sequentially deposited on the positive electrode layer 2 and the insulating layer 3. That is, when manufacturing a solid-state battery, the negative electrode layer 5 can be deposited after the positive electrode layer 2 is densified, thus avoiding the application of large pressure to the negative electrode layer 5 in the stacking direction X.

[0042] Specifically, in solid-state batteries, the negative electrode layer 5 uses a lithium-ion-capturing material such as porous silicon or carbon as the negative electrode active material. If a large pressure is applied to the negative electrode layer 5 in the stacking direction X, the voids in the negative electrode active material may be crushed or the negative electrode active material itself may be crushed, which may reduce its lithium-ion-capturing function. In the solid-state battery of this disclosure, it is possible to avoid applying large pressure to the negative electrode layer 5 in the stacking direction X, thus preventing the reduction of the lithium-ion-capturing function of the negative electrode active material.

[0043] <Elements of Solid State Batteries>

[0044] (Positive current collector)

[0045] For the positive electrode current collector, any of those commonly used as positive electrode current collectors for batteries can be employed. Furthermore, the positive electrode current collector can be, for example, foil, plate, mesh, perforated metal, or foam. The positive electrode current collector can be constructed from metal foil or metal mesh. In particular, metal foil has excellent processing properties. The positive electrode current collector can contain multiple foils. Examples of metals used to construct the positive electrode current collector include Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, and stainless steel. In particular, for example, from the viewpoint of ensuring oxidation resistance, the positive electrode current collector may contain Al. For example, for the purpose of adjusting resistance, the positive electrode current collector may have some kind of coating on its surface. Furthermore, the positive electrode current collector may contain metal foil or substrate on which the aforementioned metals are plated or vapor-deposited. It should be noted that when, for example... Figure 1 When a positive electrode layer is stacked on top of the positive electrode current collector as shown, an Al foil (e.g., an Al foil with a thickness of 10 μm) can be used as the positive electrode current collector.

[0046] (Positive electrode layer)

[0047] The positive electrode layer comprises at least a positive electrode active material, and optionally may also comprise, for example, an electrolyte, conductive additives, and a binder. In addition to these, the positive electrode layer may also comprise various additives. As the positive electrode active material, materials known as positive electrode active materials for secondary batteries can be used. The positive electrode active material can be at least one selected from various lithium-containing compounds, elemental sulfur, and sulfur compounds. The lithium-containing compound used as the positive electrode active material can be various lithium-containing oxides, such as lithium cobalt oxide, lithium nickel oxide, and Lithium oxide. 1±α Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O 2±δ Lithium manganese oxide, spinel-based lithium compounds (with Li...) 1+ x Mn 2-x-y M y Li-Mn spinel with heteroelemental substitutions, represented by O4 (where M is one or more selected from Al, Mg, Co, Fe, Ni, and Zn), lithium titanate, and lithium metal phosphates (e.g., LiMPO4, where M is one or more selected from Fe, Mn, Co, and Ni). In particular, greater effects can be expected when the positive electrode active material comprises a lithium-containing oxide containing at least Li, at least one selected from Ni, Co, and Mn, and O as a constitutive element. Only one type of positive electrode active material can be used alone, or a combination of two or more can be used.

[0048] The shape of the positive electrode active material can be any shape commonly found in battery positive electrode active materials. The positive electrode active material can be, for example, particulate. It can be solid, hollow, porous, or have voids. It can be primary particles or secondary particles formed by agglomeration of multiple primary particles. Furthermore, a protective layer containing an ion-conducting oxide can be formed on the surface of the positive electrode active material. Therefore, the reaction between the positive electrode active material and sulfides (e.g., sulfide solid electrolytes) is more easily suppressed. Examples of ion-conducting oxides include Li3BO3, LiBO2, Li2CO3, LiAlO2, Li4SiO4, Li2SiO3, Li3PO4, Li2SO4, Li2TiO3, and Li4Ti5O. 12 Li2Ti2O5, Li2ZrO3, LiNbO3, Li2MoO4 and Li2WO4.

[0049] (Solid electrolyte)

[0050] The solid electrolyte contained in the solid electrolyte layer preferably comprises at least one type of solid electrolyte selected from the group consisting of sulfide solid electrolytes, oxide solid electrolytes and halide solid electrolytes.

[0051] The sulfide solid electrolyte preferably contains sulfur (S) as the main anionic element, and in addition to containing S, it preferably also contains, for example, Li, A, and S. A is at least one selected from the group consisting of P, As, Sb, Si, Ge, Sn, B, Al, Ga, and In. The sulfide solid electrolyte may further contain at least one of O and a halogen. Examples of halogens (X) include F, Cl, Br, and I. The composition of the sulfide solid electrolyte is not particularly limited, and examples include xLi₂S·(100-x)P₂S₅ (70≤x≤80) and yLiI·zLiBr·(100-yz) (xLi₂S·(1-x)P₂S₅) (0.7≤x≤0.8, 0≤y≤30, and 0≤z≤30).

[0052] Sulfide solid electrolytes may have the composition given by the following general formula (1).

[0053] Li 4-x Ge 1-x P x S4(0<x<1)····Formula (1)

[0054] In formula (1), at least a portion of Ge can be substituted with at least one selected from the group consisting of Sb, Si, Sn, B, Al, Ga, In, Ti, Zr, V, and Nb. Furthermore, at least a portion of P can be substituted with at least one selected from the group consisting of Sb, Si, Sn, B, Al, Ga, In, Ti, Zr, V, and Nb. A portion of Li can be substituted with at least one selected from the group consisting of Na, K, Mg, Ca, and Zn. A portion of S can be substituted with a halogen. The halogen is at least one selected from F, Cl, Br, and I.

[0055] Oxide solid electrolytes preferably contain oxygen (O) as the main anionic element, and may contain, for example, Li, Q (Q representing at least one of Nb, B, Al, Si, P, Ti, Zr, Mo, W, and S), and O. Examples of oxide solid electrolytes include garnet-type solid electrolytes, perovskite-type solid electrolytes, NASICON-type solid electrolytes, Li-PO4-based solid electrolytes, and Li-BO4-based solid electrolytes. Examples of garnet-type solid electrolytes include Li7La3Zr2O. 12 Li 7-x La3(Zr 2-x Nb x )O 12 (0≤x≤2) and Li5La3Nb2O 12Examples of perovskite-type solid electrolytes include (Li,La)TiO3, (Li,La)NbO3, and (Li,Sr)(Ta,Zr)O3. Examples of NASICON-type solid electrolytes include Li(Al,Ti)(PO4)3 and Li(Al,Ga)(PO4)3. Examples of Li-P-O-based solid electrolytes include Li3PO4 and LIPON (a compound in which a part of O in Li3PO4 is replaced by N), and examples of Li-B-O-based solid electrolytes include Li3BO3 and a compound in which a part of O in Li3BO3 is replaced by C.

[0056] As the halide solid electrolyte, a solid electrolyte containing Li, M, and X (M represents at least one of Ti, Al, and Y, and X represents F, Cl, or Br) is preferred. Specifically, Li 6-3z Y z X6 (X represents Cl or Br, and z satisfies 0 < z < 2) and Li 6-(4-x)b (Ti 1-x Al x ) b F6 (0 < x < 1 and 0 < b ≤ 1.5) is preferred. In Li 6-3z Y z X6, Li3YX6 (X represents Cl or Br) is more preferred in terms of excellent lithium ion conductivity, and Li3YCl6 is even more preferred. Further, from the viewpoints such as suppressing the oxidative decomposition of the sulfide solid electrolyte, etc., Li 6-(4-x)b (Ti 1-x Al x ) b F6 (0 < x < 1 and 0 < b ≤ 1.5) is preferably included together with a solid electrolyte such as a sulfide solid electrolyte.

[0057] (Solid electrolyte layer)

[0058] Examples of the solid electrolyte layer include electrolyte layers used in semi-solid batteries and all-solid-state batteries. The thickness of the solid electrolyte layer is not particularly limited, and can be selected from, for example, the range of 1 μm to 30 μm. The type of the solid electrolyte contained in the solid electrolyte layer is not particularly limited. For example, the solid electrolyte can be selected from the solid electrolytes that can be contained in the above electrode layer. The solid electrolyte layer can be a single layer or a multi-layer structure having two or more layers.

[0059] When the solid-state battery of this disclosure includes a solid electrolyte, it may include an electrolyte comprising less than 10% by mass of the total electrolyte amount together with the solid electrolyte. When the battery of this disclosure includes a solid electrolyte, the solid electrolyte may be a composite solid electrolyte comprising an inorganic solid electrolyte and a polymer electrolyte. When the solid-state battery of this disclosure includes an electrolyte as the electrolyte, there are no particular limitations on the type of electrolyte, and known electrolytes may be used. Specific examples of electrolytes include liquids in which lithium salts such as LiPF6 or LiFSi are dissolved in an organic solvent.

[0060] (Negative electrode layer)

[0061] The negative electrode layer comprises at least a negative electrode active material and may optionally include, for example, an electrolyte, conductive additives, and a binder. In addition to these, the negative electrode layer may also contain a variety of additives. Examples of negative electrode active materials include carbon materials, active materials containing Si, lithium metal, lithium-containing alloys, metals or alloys capable of alloying with lithium, oxides, and transition metal nitrides. Examples of carbon materials include graphite materials, amorphous carbon materials, carbon black, and activated carbon. Examples of graphite materials include natural graphite and artificial graphite. Examples of amorphous carbon materials include hard carbon, soft carbon, coke, mesophase carbon microspheres (MCMB), and mesophase pitch carbon fibers (MCF). Graphite materials may be coated with metals or amorphous carbon. Examples of active materials containing Si include elemental silicon, silicon alloys (e.g., alloys of Si and one or more metals selected from the group consisting of Sn, Ti, Fe, Ni, Cu, Co, and Al), porous silicon, silicon inclusion compounds, and silicon oxides.

[0062] (Negative electrode current collector)

[0063] For the negative electrode current collector, any of those commonly used as negative electrode current collectors in batteries can be used. Furthermore, the negative electrode current collector can be, for example, foil, plate, mesh, perforated metal, or foam. The negative electrode current collector can be a metal foil or metal mesh, or it can be a carbon sheet. The negative electrode current collector can comprise multiple foils or sheets. Examples of metals used to construct the negative electrode current collector include Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, and stainless steel. In particular, from the viewpoint of ensuring resistance to reduction and difficulty in alloying with lithium, the negative electrode current collector can comprise at least one metal selected from Cu, Ni, and stainless steel.

[0064] For purposes such as adjusting resistance, the negative current collector may have a coating on its surface. Furthermore, the negative current collector may comprise a metal foil or substrate on which the aforementioned metal is plated or vapor-deposited. Additionally, when the negative current collector comprises multiple metal foils, a layer may be included between the multiple metal foils. The thickness of the negative current collector is not particularly limited. For example, the thickness may be 0.1 μm or more, 1 μm or more and 1 mm or less, or 100 μm or less. For example, in... Figure 1 The solid-state battery shown has a nickel plating layer (corresponding to...) Figure 1 The Al foil (corresponding to the first negative current collector 7A) in the middle Figure 1 The second negative electrode current collector 7B can be used as a negative electrode current collector. More specifically, for example, an Al foil with a thickness of 10 μm and a nickel plating layer of 1 μm thickness stacked on it can be used as each negative electrode current collector.

[0065] (Carbon coating)

[0066] The carbon coating serves as an adhesive layer for bonding the negative electrode current collector to the negative electrode layer, and also as a conductive layer for ensuring electrical continuity between the negative electrode current collector and the negative electrode layer. Examples of carbon materials included in the carbon coating include graphite materials, amorphous carbon materials, carbon black, and activated carbon. Examples of graphite materials include natural graphite and artificial graphite. Examples of amorphous carbon materials may include hard carbon, soft carbon, coke, mesophase carbon microspheres (MCMB), and mesophase pitch carbon fibers (MCF).

[0067] (Packaging)

[0068] The solid-state battery of this disclosure may also include a package. The package at least contains an electrode stack. Examples of packages include laminated packages and shell-type packages. A laminated package may be formed of a laminate (laminated film) having a metal layer comprising a metal such as aluminum and a heat-sealing layer comprising a resin that melts when heated.

[0069] (Constrained Members)

[0070] The solid-state battery disclosed herein may also include a constraint member. The constraint member applies a constraint pressure to the electrode stack in the thickness direction of the electrode stack. The constraint pressure applied in the thickness direction of the electrode stack may be, for example, 0.1 MPa or more, 1 MPa or more, or 5 MPa or more. The constraint pressure applied in the thickness direction of the electrode stack may be, for example, 100 MPa or less, 50 MPa or less, or 20 MPa or less.

[0071] Solid-state battery manufacturing methods

[0072] The solid-state battery manufacturing method of this disclosure includes the steps of: forming a positive electrode layer and an insulating layer adjacent to and flush with the end of the positive electrode layer on at least one main surface of a positive electrode current collector; and forming a solid electrolyte layer on the positive electrode layer and the insulating layer such that the end of the solid electrolyte layer overlaps with the insulating layer. According to the solid-state battery manufacturing method of this disclosure, even when pressure is applied in the stacking direction of the positive electrode current collector, the positive electrode layer, and the solid electrolyte layer, damage to the solid electrolyte layer can be prevented. In particular, in the solid-state battery manufacturing method of this disclosure, it is preferable that after forming the positive electrode layer and the insulating layer on the main surface of the positive electrode current collector, the positive electrode layer is densified by compressing the positive electrode layer and the insulating layer in the stacking direction.

[0073] Next, in the solid-state battery manufacturing method of this disclosure, a negative electrode layer is formed such that, in a cross-sectional view along the stacking direction of the positive current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the end of the negative electrode layer overlaps with the solid electrolyte layer and the insulating layer.

[0074] Regarding the solid-state battery manufacturing method disclosed herein, Figure 1 Taking the solid-state battery shown as an example, firstly, a positive electrode layer 2 and an insulating layer 3 are formed on the two main surfaces of the positive electrode current collector 1. Then, a solid electrolyte layer 4 is formed on the positive electrode layer 2 and the insulating layer 3, such that its ends overlap with the insulating layer 3. Next, a negative electrode layer 5, a carbon coating 6, and a negative electrode current collector 7 are sequentially formed on the solid electrolyte layer 4, thereby enabling the fabrication of a solid-state battery. Figure 1 The solid-state battery shown is preferably constructed by forming a positive electrode layer 2 and an insulating layer 3 on the two main surfaces of the positive electrode current collector 1, and then densifying the positive electrode layer 2 formed on the two main surfaces of the positive electrode current collector 1 by compressing it in the stacking direction X in a manner that sandwiches the positive electrode current collector 1. Then, a solid electrolyte layer 4 is formed after the positive electrode layer 2 has been densified. It should be noted that by compressing the solid electrolyte layer 4 in the stacking direction X in a manner that sandwiches the positive electrode current collector 1 after its formation, both the positive electrode layer 2 and the solid electrolyte layer 4 can be densified simultaneously.

[0075] Subsequently, a negative electrode layer 5 is formed on the solid electrolyte layer 4. At this time, the negative electrode layer 5 is formed such that its end on the positive current collector tab side 1A overlaps with the solid electrolyte layer 4 and the insulating layer 3. Then, the carbon coating 6, which comprises the negative current collector 7 and the carbon coating 6, is adhered to the negative electrode layer 5. Thus, the carbon coating 6 and the negative current collector 7 can be formed on the negative electrode layer 5.

[0076] According to the solid-state battery manufacturing method of this disclosure, the solid electrolyte layer 4 is formed such that its end face overlaps with the insulating layer 3 rather than with the positive electrode layer 2. Therefore, even when pressure is applied to the solid-state battery in the stacking direction X, damage to the solid electrolyte layer 4 can be prevented, particularly damage to the area near the end face of the solid electrolyte layer 4. Furthermore, according to the solid-state battery manufacturing method of this disclosure, the negative electrode layer 5 can be provided after the positive electrode layer 2 has been densified, thus avoiding the application of large pressures to the negative electrode layer 5 in the stacking direction X.

[0077] <Other Implementation Method 1>

[0078] The solid-state batteries disclosed herein are not limited to Figure 1 The configuration shown may include an adhesive layer between the positive current collector and the positive electrode layer and insulating layer. In this case, the positive electrode layer and insulating layer are also formed on at least one main surface of the positive current collector, and the method can be adopted in which an adhesive layer is formed on one main surface of the positive current collector, and then the positive electrode layer and insulating layer formed on the transfer member are transferred to the adhesive layer. In the following, the same components as in the above embodiment are indicated by the same reference numerals, and their detailed description will be omitted here.

[0079] Specifically, such as Figure 3 As shown, the solid-state battery of this disclosure may have an adhesive layer 9 between the positive electrode current collector 1 and the positive electrode layer 2 and the insulating layer 3. Figure 3 In the solid-state battery shown, the adhesive layer 9 is constructed as a single layer, thereby covering the entirety of the two main surfaces of the positive electrode current collector 1. However, it can also be formed in an island shape on a portion of the two main surfaces of the positive electrode current collector 1. That is, the adhesive layer 9 can be a layer covering the entirety of the two main surfaces of the positive electrode current collector 1, or it can be in an island shape, as long as it has the function of adhering the positive electrode layer 2 and the insulating layer 3 to the two main surfaces of the positive electrode current collector 1.

[0080] In particular, the adhesive layer 9 is preferably conductive. When the adhesive layer 9 is conductive, even when the adhesive layer 9 is laminated as a layer on the positive current collector 1, the electrical connection between the positive current collector 1 and the positive layer 2 can be ensured.

[0081] Furthermore, the thickness of the adhesive layer 9 is not particularly limited, but is preferably 0.5 μm to 1.5 μm, more preferably 0.5 μm to 1.0 μm, and even more preferably 0.8 μm to 1.0 μm. By setting the thickness of the adhesive layer 9 within this range, even if the adhesive layer 9 is not conductive, the positive electrode active material contained in the positive electrode layer 2 penetrates the adhesive layer 9, thus ensuring the electrical connection between the positive electrode current collector 1 and the positive electrode layer 2.

[0082] Figure 3The solid-state batteries shown are not particularly limited. For example, such as... Figures 4A to 4D As shown, the following method can be applied, wherein the positive electrode layer 2 and the insulating layer 3 are formed on the transfer member 10, and then the positive electrode layer 2 and the insulating layer 3 are transferred to the adhesive layer 9 already formed on the positive electrode current collector 1. Specifically, firstly, as shown... Figure 4A As shown, a positive electrode paste containing a positive electrode active material is coated onto one main surface of the transfer member 10 to form a positive electrode layer 2. At this time, due to the coating and sagging of the positive electrode paste coated on one main surface of the transfer member 10, the periphery of the positive electrode layer 2 becomes an inclined surface. Thereafter, as... Figure 4B As shown, the inclined surface of the positive electrode layer 2 caused by coating sagging is removed. Then, as... Figure 4C As shown, an insulating slurry containing insulating material is applied, making it contact the end face of the positive electrode layer 2. At this time, due to the coating and dripping of the insulating slurry, the periphery of the insulating layer 3 becomes an inclined surface. Subsequently, as... Figure 4D As shown, the inclined surface of the insulating layer 3 caused by coating dripping is removed. In the manner described above, the positive electrode layer 2 and the insulating layer 3 can be formed on a main surface of the transfer member 10.

[0083] exist Figure 3 In the solid-state battery shown, by removing the inclined surfaces of the positive electrode layer 2 and the insulating layer 3 caused by coating drips, the area usable as the positive electrode layer 2 can be designed to be wide, and battery performance can be improved. Furthermore, in Figure 3 In the solid-state battery shown, by removing the inclined surface of the insulating layer 3 caused by coating drips, the mechanical strength of the end of the insulating layer 3 on the positive current collector tab side 1A side can be improved. Specifically, as... Figure 5 As shown, in the cross-sectional view, the tilt angle α of the end face of the positive electrode layer 2 adjacent to the insulating layer 3 and the tilt angle β of the end face of the insulating layer 3 on the opposite side to the end face adjacent to the positive electrode layer 2 are preferably within the range of ±10°, more preferably within the range of ±5°, relative to the stacking direction X. By setting the tilt angles α and β within this range, the area that can be used as the positive electrode layer 2 can be designed to be wide, and battery performance can be improved.

[0084] Furthermore, when using the transfer component 10 to transfer the positive electrode layer 2 and the insulating layer 3 to the adhesive layer 9, it may not be as described above. Figures 4A to 4D Instead of removing the inclined surfaces of both the positive electrode layer 2 and the insulating layer 3 caused by coating drips, only the inclined surface of the insulating layer 3 is removed. In this case, as shown... Figure 6 As shown, the solid-state battery has the following characteristic: in the cross-sectional view, the inclination angle of the end face of the insulating layer 3 opposite to the end face of the adjacent positive electrode layer 2 is closer to 90° compared to the inclination angle of the end face of the adjacent insulating layer 3 of the positive electrode layer 2. In this case, as... Figure 7AAs shown, a positive electrode paste containing a positive electrode active material is coated onto one main surface of the transfer member 10 to form a positive electrode layer 2. At this time, due to the coating and sagging of the positive electrode paste coated on one main surface of the transfer member 10, the end of the positive electrode layer 2 becomes an inclined surface. Thereafter, as... Figure 7B As shown, an insulating slurry containing insulating material is applied to cover the inclined surface of the positive electrode layer 2. At this time, due to the coating and dripping of the insulating slurry, the ends of the insulating layer 3 become inclined surfaces. Subsequently, as... Figure 7C As shown, the inclined surface of the insulating layer 3 caused by coating dripping is removed. In the manner described above, a positive electrode layer 2 with an inclined surface and an insulating layer 3 with its inclined surface removed can be formed on a main surface of the transfer member 10.

[0085] exist Figure 6 In the solid-state battery shown, the mechanical strength of the end of the insulating layer 3 on the positive electrode current collector tab side 1A side can be improved by removing the inclined surface of the insulating layer 3 caused by coating sagging. Specifically, as Figure 8 As shown, the inclination angle δ of the end face of the insulating layer 3 opposite to the end face adjacent to the positive electrode layer 2 can be manufactured to be closer to 90° than the inclination angle γ of the end face of the positive electrode layer 2 adjacent to the insulating layer 3. Therefore, the mechanical strength of the end of the insulating layer 3 on the positive electrode current collector tab side end 1A side can be improved.

[0086] <Battery Types and Applications>

[0087] There are no particular limitations on the type of solid-state battery, and it is typically a lithium-ion battery. Furthermore, the solid-state battery of this disclosure can be a primary battery or a secondary battery, but a secondary battery is preferred. This is because secondary batteries can be repeatedly charged and discharged, and are used, for example, as automotive batteries. Solid-state batteries can be semi-solid-state batteries, such as batteries having a gel layer containing an electrolyte and a polymer between the electrodes and a solid electrolyte layer, or they can be all-solid-state batteries using a solid electrolyte as the electrolyte. The solid electrolyte may contain less than 10% by mass of electrolyte relative to the total amount of electrolyte. Solid-state batteries are preferably all-solid-state batteries.

[0088] The uses of the batteries disclosed herein are not particularly limited. Examples of representative uses include power sources for vehicles, electronic devices, and electrical storage systems. Batteries can be used as power sources for mobile bodies other than vehicles (e.g., trains, ships, and aircraft), and can be used as power sources for electrical products such as information processing equipment. Preferably, the batteries disclosed herein are used as power sources for vehicles, and more preferably as power sources for driving hybrid electric vehicles, plug-in hybrid electric vehicles, or battery electric vehicles.

[0089] Examples of vehicles include four-wheeled electric vehicles, two-wheeled electric vehicles, gasoline-powered cars, and diesel-powered cars. Examples of four-wheeled electric vehicles include battery electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), and hybrid electric vehicles (HEVs). Examples of two-wheeled electric vehicles include electric bicycles and electric-assist bicycles.

Claims

1. A solid-state battery, comprising: Positive current collector; A positive electrode layer is disposed on at least one main surface of the positive electrode current collector; An insulating layer is disposed on at least one main surface of the positive current collector, adjacent to an end of the positive electrode layer, and flush with the positive electrode layer; and A solid electrolyte layer is disposed on the positive electrode layer and the insulating layer, with its ends located at positions overlapping with the insulating layer.

2. The solid-state battery according to claim 1, wherein, The positive current collector includes a positive current collector tab side end connected to the positive current collector tab, and wherein the insulating layer and the positive electrode layer are sequentially disposed from the positive current collector tab side end.

3. The solid-state battery according to claim 1, comprising an adhesive layer between the positive current collector and the positive electrode layer and the insulating layer.

4. The solid-state battery according to claim 3, wherein, The adhesive layer is conductive.

5. The solid-state battery according to claim 3, wherein, The adhesive layer has a thickness of 0.5 μm to 1.5 μm.

6. The solid-state battery according to claim 1, further comprising a negative electrode layer disposed on the solid electrolyte layer, wherein, in a cross-sectional view along the stacking direction of the positive current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the end of the negative electrode layer is located at a position overlapping the solid electrolyte layer and the insulating layer.

7. The solid-state battery according to any one of claims 1 to 6, wherein, In a cross-sectional view along the stacking direction of the positive current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the tilt angle of the end face of the positive electrode layer adjacent to the insulating layer and the tilt angle of the end face of the insulating layer on the opposite side to the end face adjacent to the positive electrode layer are within ±10° relative to the stacking direction.

8. The solid-state battery according to any one of claims 1 to 6, wherein, In a cross-sectional view along the stacking direction of the positive current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the inclination angle of the end face of the insulating layer on the side opposite to the end face adjacent to the positive electrode layer is closer to 90° than the inclination angle of the end face of the positive electrode layer adjacent to the insulating layer.

9. A method for manufacturing a solid-state battery, the method comprising: A positive electrode layer and an insulating layer adjacent to and flush with the end of the positive electrode layer are formed on at least one main surface of the positive electrode current collector; as well as A solid electrolyte layer is formed on the positive electrode layer and the insulating layer, such that the end of the solid electrolyte layer overlaps with the insulating layer.

10. The method of manufacturing a solid-state battery according to claim 9, further comprising forming a negative electrode layer such that, in a cross-sectional view along the stacking direction of the positive current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the end of the negative electrode layer overlaps with the solid electrolyte layer and the insulating layer.

11. The method for manufacturing a solid-state battery according to claim 9, wherein, When forming the positive electrode layer and the insulating layer, an adhesive layer is formed on at least one main surface of the positive electrode current collector, and the positive electrode layer and the insulating layer that have already been formed on the transfer member are transferred to the adhesive layer.

12. The method for manufacturing a solid-state battery according to claim 11, wherein, The adhesive layer is conductive.

13. The method for manufacturing a solid-state battery according to claim 11, wherein, The adhesive layer has a thickness of 0.5 μm to 1.5 μm.

14. The method for manufacturing a solid-state battery according to claim 11, wherein, A positive electrode paste containing a positive electrode active material is applied to the transfer member. Then, the inclined surface of the peripheral portion of the applied positive electrode paste is cut off, and an insulating paste containing an insulating material is applied to the peripheral portion of the positive electrode paste. Then, the inclined surface of the peripheral portion of the applied insulating paste is cut off.

15. The method for manufacturing a solid-state battery according to claim 14, wherein, In a cross-sectional view along the stacking direction of the positive current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the tilt angle of the end face of the positive electrode layer adjacent to the insulating layer and the tilt angle of the end face of the insulating layer on the opposite side to the end face adjacent to the positive electrode layer are within ±10° relative to the stacking direction.

16. The method for manufacturing a solid-state battery according to claim 11, wherein, A positive electrode paste containing a positive electrode active material is coated onto the transfer member, and then an insulating paste containing an insulating material is coated to cover the inclined surface of the peripheral portion of the coated positive electrode paste. The inclined surface of the peripheral portion of the coated insulating paste is then cut off.

17. The method for manufacturing a solid-state battery according to claim 16, wherein, In a cross-sectional view along the stacking direction of the positive current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the inclination angle of the end face of the insulating layer on the side opposite to the end face adjacent to the positive electrode layer is closer to 90° than the inclination angle of the end face of the positive electrode layer adjacent to the insulating layer.

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