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

Abstract

The device has a structure in which a positive electrode layer and a solid electrolyte layer are sequentially stacked on a positive electrode current collector, preventing damage to the solid electrolyte layer even when pressure is applied in the stacking direction. [Solution] The solid battery comprises a positive electrode current collector, a positive electrode layer disposed on at least one main surface of the positive electrode current collector, an insulating layer disposed on the one main surface of the positive electrode current collector in contact with the 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 overlapping the insulating layer.

Description

[Technical Field]

[0001] This disclosure relates to a solid-state battery and a method for manufacturing a solid-state battery. [Background technology]

[0002] In recent years, the importance of rechargeable batteries has increased, and in addition to rechargeable batteries with electrolytes, the development of solid-state batteries using solid electrolytes is progressing. All-solid-state batteries, an example of solid-state batteries, are batteries that have a solid electrolyte layer instead of an electrolyte, and because they do not use flammable organic solvents, safety devices can be simplified, and they are superior in terms of manufacturing cost and productivity.

[0003] Patent Document 1 discloses a solid-state battery in which a first electrode layer, a solid electrolyte layer, and a second electrode layer are stacked in that order, wherein a first insulating layer is disposed on the outer periphery of the first electrode layer, and the size of the stacked surface with the stacking direction as the normal direction is such that the first electrode layer is smaller than the solid electrolyte layer, and 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 located on the outer periphery of the solid electrolyte layer, and the first electrode layer, first insulating layer, and solid electrolyte layer are arranged so that the outer edge of the first insulating layer and the end of the solid electrolyte layer are in contact. In the solid-state battery disclosed in Patent Document 1, it is stated that the bending and damage of the solid electrolyte layer can be suppressed because the thickness of the first insulating layer is less than or equal to the thickness of the first electrode layer.

[0004] Furthermore, Patent Document 2 discloses a solid-state battery in which the positive electrode layer formed on the positive electrode current collector has an inclined surface that slopes toward the positive electrode current collector, and this inclined surface is covered with an ion conductor layer having a lower Young's modulus than the solid electrolyte layer. According to Patent Document 2, even if the positive electrode layer expands and contracts due to charging and discharging, stress concentration on the solid electrolyte layer at the corners of the positive electrode layer can be suppressed. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2012-114497 [Patent Document 2] Japanese Patent Publication No. 2023-107428 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, there was a risk of damage to the solid electrolyte layer when pressure was applied in the stacking direction to a structure in which a positive electrode layer and a solid electrolyte layer are sequentially stacked on a positive electrode current collector. Therefore, one embodiment of this disclosure aims to provide a solid-state battery and a method for manufacturing a solid-state battery that have a structure in which a positive electrode layer and a solid electrolyte layer are sequentially stacked on a positive electrode current collector, and that can prevent damage to the solid electrolyte layer even when pressure is applied in the stacking direction. [Means for solving the problem]

[0007] Having achieved the objectives described above, this disclosure includes the following aspects: <1> A solid-state battery comprising: a positive electrode current collector; a positive electrode layer disposed on at least one main surface of the positive electrode current collector; an insulating layer disposed on the one main surface of the positive electrode current collector, in contact with the 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 overlapping the insulating layer. <2> The positive electrode current collector has a positive electrode current collector tab-side end connected to the positive electrode current collector tab, and the insulating layer and the positive electrode layer are arranged in this order from the positive electrode current collector tab-side end. <1> Solid-state batteries as described above. <3> An adhesive layer is provided between the positive electrode current collector, the positive electrode layer, and the insulating layer. <1> or <2> Solid-state batteries as described above. <4> The adhesive layer is conductive. <3> Solid-state batteries as described above. <5> The adhesive layer has a thickness of 0.5 μm to 1.5 μm. <3> Solid-state batteries as described above. <6> The negative electrode layer is further disposed on the solid electrolyte layer, and the end of the negative electrode layer is located at a position that overlaps the solid electrolyte layer and the insulating layer in a cross-sectional view along the stacking direction of the positive electrode current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer. <1> ~ <5> A solid battery as described in any one of the following. <7> In a cross-sectional view along the lamination direction of the positive electrode current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the inclination angle of the end face of the positive electrode layer in contact with the insulating layer and the inclination angle of the end face of the insulating layer opposite to the end face in contact with the positive electrode layer are within the range of ±10° with respect to the lamination direction. <1> ~ <6> A solid battery as described in any one of the following. <8> In a cross-sectional view along the lamination direction of the positive electrode current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the angle of inclination of the end face of the insulating layer opposite to the end face in contact with the positive electrode layer is closer to 90° than the angle of inclination of the end face of the positive electrode layer in contact with the insulating layer. <1> ~ <6> A solid battery as described in any one of the following. <9> A method for manufacturing a solid battery, comprising the steps of: forming a positive electrode layer and an insulating layer on at least one main surface of a positive electrode current collector, the insulating layer in contact with the end of the positive electrode layer and flush with the positive electrode layer; and forming a solid electrolyte layer on the positive electrode layer and the insulating layer such that its end overlaps the insulating layer. <10> The process further includes forming a negative electrode layer such that, in a cross-sectional view along the lamination direction of the positive electrode current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the ends of the negative electrode layer overlap the solid electrolyte layer and the insulating layer. <9> A method for manufacturing a solid-state battery as described above. <11> In the step of forming the positive electrode layer and the insulating layer, an adhesive layer is formed on one main surface of the positive electrode current collector, and the positive electrode layer and the insulating layer formed on the transfer member are transferred to the adhesive layer. <9> or <10> A method for manufacturing a solid-state battery as described above. <12> The adhesive layer is conductive. <11> A method for manufacturing a solid-state battery as described above. <13> The adhesive layer has a thickness of 0.5 μm to 1.5 μm. <11> A method for manufacturing a solid-state battery as described above. <14>Apply a positive electrode slurry containing a positive electrode active material to the transfer member, and then cut off the inclined surface of the peripheral edge of the applied positive electrode slurry, and apply an insulating slurry containing an insulating material so as to contact the peripheral edge of the positive electrode slurry, and then cut off the inclined surface of the peripheral edge of the applied insulating slurry. The method for manufacturing a solid-state battery according to <11>. <15>In a cross-sectional view along the stacking direction of the positive electrode current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the inclination angle of the end surface of the positive electrode layer that contacts the insulating layer and the inclination angle of the end surface of the insulating layer on the side opposite to the end surface that contacts the positive electrode layer are within the range of ±10° with respect to the stacking direction. The method for manufacturing a solid-state battery according to <14>. <16>Apply a positive electrode slurry containing a positive electrode active material to the transfer member, and then apply an insulating slurry containing an insulating material so as to cover the inclined surface of the peripheral edge of the applied positive electrode slurry, and then cut off the inclined surface of the peripheral edge of the applied insulating slurry. The method for manufacturing a solid-state battery according to <11>. <17>In a cross-sectional view along the stacking direction of the positive electrode current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the inclination angle of the end surface of the insulating layer on the side opposite to the end surface that contacts the positive electrode layer is closer to 90° than the inclination angle of the end surface of the positive electrode layer that contacts the insulating layer. The method for manufacturing a solid-state battery according to <16>.

Advantages of the Invention

[0008] According to one embodiment of the present disclosure, even when pressure is applied in the stacking direction to a structure in which a positive electrode layer and a solid electrolyte layer are sequentially stacked on a positive electrode current collector, damage to the solid electrolyte layer can be prevented.

Brief Description of the Drawings

[0009] [Figure 1] It is a cross-sectional view of a main part of a solid-state battery shown as one embodiment of the present disclosure. [Figure 2] It is a schematic plan view showing an example of a position where the surface of a solid-state battery in a plan view seen from above is cut by a plane parallel to the first axis direction. [Figure 3]This is a cross-sectional view of a key part of a solid-state battery, as shown in another embodiment of the present disclosure. [Figure 4] This is a cross-sectional view of a key part showing the process of forming a positive electrode layer and an insulating layer on a transfer member. [Figure 5] This is a cross-sectional view of a key part showing the inclination angles of the end faces of the positive electrode layer and the insulating layer formed on the transfer member. [Figure 6] This is a cross-sectional view of a key part of a solid-state battery shown as yet another embodiment of the present disclosure. [Figure 7] This is a cross-sectional view of a key part showing the process of forming a positive electrode layer and an insulating layer on a transfer member. [Figure 8] This is a cross-sectional view of a key part showing the inclination angles of the end faces of the positive electrode layer and the insulating layer formed on the transfer member. [Modes for carrying out the invention]

[0010] In this disclosure, a numerical range indicated using "~" means a range that includes the numbers written before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. In the numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples. In this disclosure, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, as long as their intended purpose is achieved. In this disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In this disclosure, unless otherwise specified, the amount of each component refers to the total amount of multiple substances if there are multiple substances corresponding to each component. When embodiments are described in this disclosure with reference to the drawings, the configuration of such embodiments is not limited to the configuration shown in the drawings. Furthermore, the sizes of the components in each figure are conceptual, and the relative relationships between the sizes of the components are not limited thereto.

[0011] <Solid battery> The solid-state battery of this disclosure is described below. The solid-state battery of this disclosure comprises a positive electrode current collector, a positive electrode layer disposed on at least one main surface of the positive electrode current collector, an insulating layer disposed on the one main surface of the positive electrode current collector in contact with the 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 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 electrode current collector, the positive electrode layer and the solid electrolyte layer (for example, when the current collector or electrode layer is pressed tightly together in the stacking direction, or when subjected to an external force in the stacking direction).

[0012] As shown in Figure 1, a solid-state battery as one embodiment of the present disclosure comprises a positive electrode current collector 1, a positive electrode layer 2 and an insulating layer 3 disposed on both 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 layer 6 disposed on the negative electrode layer 5, and a negative electrode current collector 7 disposed on the carbon coating layer 6.

[0013] Furthermore, in the solid-state battery shown in Figure 1, the positive electrode current collector 1 has a positive electrode current collector tab-side end 1A that is connected to the positive electrode current collector tab. The insulating layer 3 and the positive electrode layer 2 are arranged in this order from the positive electrode current collector tab-side end 1A. The solid-state battery shown in Figure 1 has an end insulating portion 8 at the end of the positive electrode current collector 1 opposite to the positive electrode current collector tab-side end 1A. In this disclosure, the stacking direction refers to the direction in which the positive electrode current collector 1, positive electrode layer 2, solid electrolyte layer 4, etc. are stacked, as indicated by the arrow X in Figure 1.

[0014] In the solid-state battery shown in Figure 1, the negative electrode layer 5 is divided into two layers: a first negative electrode layer 5A located on top of the solid electrolyte layer 4, and a second negative electrode layer 5B located on top of the first negative electrode layer 5A. However, the negative electrode layer 5 may be a single layer or may have two or more layers. Also, in the solid-state battery shown in Figure 1, the negative electrode current collector 7 is divided into two layers: a first negative electrode current collector 7A located on top of the negative electrode layer 5, and a second negative electrode current collector 7B located on top of the first negative electrode current collector 7A. However, the negative electrode current collector 7 may be a single layer or may have two or more layers.

[0015] In the solid-state battery shown in Figure 1, the positive electrode layer 2 and the insulating layer 3 are formed flush with 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 at one end surface, and the main surface of the positive electrode layer 2 and the main surface of the insulating layer 3 form the same plane. In the solid-state battery shown in Figure 1, the end of the solid electrolyte layer 4 on the positive electrode current collector tab side 1A is positioned to overlap with the insulating layer 3. In other words, the end of the solid electrolyte layer 4 on the positive electrode current collector tab side 1A is positioned not to overlap with the positive electrode layer 2, and the solid electrolyte layer 4 is formed to cover the entire plane of the positive electrode layer 2.

[0016] Furthermore, in the solid-state battery shown in Figure 1, the positive electrode layer 2 is formed by applying a positive electrode slurry to the main surface of the positive electrode current collector 1 and drying it. As a result, the end face of the positive electrode layer 2 on the positive electrode current collector tab side 1A becomes an inclined surface due to coating sagging. Note that the end face of the positive electrode layer 2 opposite to the positive electrode current collector tab side 1A is cut and therefore does not become an inclined surface, but rather a surface in a direction approximately parallel to the stacking direction. Also, in the solid-state battery shown in Figure 1, the insulating layer 3 is formed after the positive electrode layer 2 with an inclined surface is formed by applying an insulating slurry containing 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 becomes an inclined surface due to coating sagging. Note that the end face of the insulating layer 3 opposite to the positive electrode current collector tab side 1A is cut and therefore does not become an inclined surface, but rather a surface in a direction approximately parallel to the stacking direction.

[0017] Furthermore, in the solid-state battery shown in Figure 1, the end of the negative electrode layer 5 on the positive electrode current collector tab side end 1A is located in a position that overlaps with 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 and the insulating layer 3, and the solid electrolyte layer 4. A cross-sectional view along the stacking direction X means a view of a cross-section obtained by cutting the solid-state battery along the stacking direction X of the battery stacking structure, and in particular, a view of a cross-section passing through the positive electrode current collector tab side end 1A and the end opposite to the positive electrode current collector tab side end 1A. More specifically, if the solid-state battery shown in Figure 1 is a prismatic battery, the cross-sectional view along the stacking direction X can be a cross-sectional view of a cross-section obtained by cutting the rectangle, viewed from the top in plan, by line AA which approximately bisects the shorter side of the rectangle, as shown in Figure 2. In Figure 2, line AA which approximately bisects the shorter side of the rectangle passes through the positive electrode current collector tab side end 1A and the end insulating portion 8.

[0018] In the solid-state battery configured as described above, the end face of the solid electrolyte layer 4, which is disposed on the positive electrode layer 2, is positioned so as to overlap the insulating layer 3 rather than the positive electrode layer 2. This prevents damage to the solid electrolyte layer 4, particularly damage near the end face of the solid electrolyte layer 4, even when pressure is applied to the solid-state battery in the stacking direction X. Here, pressure applied in the stacking direction X means pressure is applied in a direction that sandwiches the positive electrode current collector 1, the positive electrode layer 2, the insulating layer 3, the solid electrolyte layer 4, the negative electrode layer 5, and the negative electrode current collector 7. Although not shown, the solid-state battery may further include a restraining member that restrains these positive electrode layer 2, 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 restraining member applies restraining pressure in the thickness direction to the electrode stack described above. For example, the restraining pressure may be, for example, 0.1 MPa or more, 1 MPa or more, or 5 MPa or more, and may also be, for example, 100 MPa or less, 50 MPa or less, or 20 MPa or less. Even if the aforementioned pressure is applied by the restraining member, the solid-state battery of this disclosure can prevent damage to the solid electrolyte layer 4, particularly damage near the end face of the solid electrolyte layer 4.

[0019] Furthermore, in the solid-state battery shown in Figure 1, the positive electrode, including the positive electrode current collector 1 and the positive electrode layer 2, is located near the center of the stacking direction X of the electrode stack, while the negative electrode, including the negative electrode current collector 7 and the negative electrode layer 5, is located on the outer layer side of the stacking direction X of the electrode stack. In a solid-state battery configured in this way, first, the positive electrode layer 2 and the insulating layer 3 are arranged on the main surface of the positive electrode current collector 1, and then the positive electrode layer 2 can be densified by compression in the stacking direction. Subsequently, the solid electrolyte layer 4 and the negative electrode layer 5 are sequentially arranged on the positive electrode layer 2 and the insulating layer 3. In other words, when manufacturing the solid-state battery, the negative electrode layer 5 can be arranged after the positive electrode layer 2 has been densified, thus avoiding the application of large pressure to the negative electrode layer 5 in the stacking direction X.

[0020] In particular, in solid-state batteries, the negative electrode layer 5 uses a lithium-ion-absorbing material such as porous silicon or carbon material 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 may be fractured, which may reduce its lithium-ion absorption capacity. In the solid-state battery of this disclosure, it is possible to avoid applying a large pressure to the negative electrode layer 5 in the stacking direction X, thereby preventing a decrease in the lithium-ion absorption capacity of the negative electrode active material.

[0021] <Each element of a solid-state battery> (Positive electrode current collector) The positive electrode current collector can be any of the commonly used positive electrode current collectors for batteries. The positive electrode current collector may be in the form of foil, plate, mesh, perforated metal, or foam. The positive electrode current collector may be composed of metal foil or metal mesh. Metal foil, in particular, offers superior handling. The positive electrode current collector may consist of multiple foils. Examples of metals that can constitute the positive 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 oxidation resistance, the positive electrode current collector may contain Al. The positive electrode current collector may have some kind of coating layer on its surface for purposes such as adjusting resistance. Furthermore, the positive electrode current collector may be a metal foil or a substrate on which the above metals are plated or deposited. Note that when a positive electrode layer is laminated onto the positive electrode current collector, as shown in Figure 1, Al foil, for example, Al foil with a thickness of 10 μm, can be used as the positive electrode current collector.

[0022] (Positive electrode layer) The positive electrode layer contains at least a positive electrode active material and may optionally contain an electrolyte, a conductive additive, and a binder. The positive electrode layer may also contain various other additives. As the positive electrode active material, known positive electrode active materials for secondary batteries can be used. As the positive electrode active material, for example, at least one selected from various lithium-containing compounds, elemental sulfur, and sulfur compounds, etc. Lithium-containing compounds as positive electrode active materials include lithium cobaltate, lithium nickelate, Li 1±α Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O 2±δ Lithium manganate, spinel-type lithium compounds (Li 1+x Mn 2-x-y M yHeteroatom-substituted Li-Mn spinel represented by O4 (M is one or more selected from Al, Mg, Co, Fe, Ni, and Zn), etc., lithium titanate, lithium metal phosphate (such as LiMPO4, etc., M is one or more selected from Fe, Mn, Co, and Ni), and various lithium-containing oxides may be used. In particular, when the positive electrode active material contains a lithium-containing oxide containing at least Li, at least one of Ni, Co, and Mn, and O as constituent elements, a higher effect can be expected. As the positive electrode active material, only one kind may be used alone, or two or more kinds may be used in combination.

[0023] The shape of the positive electrode active material may be a general shape as the positive electrode active material of the battery. The positive electrode active material may be, for example, in a particulate form. The positive electrode active material may be solid, hollow, may have voids, or may be porous. The positive electrode active material may be primary particles or secondary particles in which a plurality of primary particles are aggregated. Further, a protective layer containing an ion-conductive oxide may be formed on the surface of the positive electrode active material. This makes it easier to suppress the reaction between the positive electrode active material and a sulfide (for example, a sulfide solid electrolyte), etc. Examples of the ion-conductive oxide include Li3BO3, LiBO2, Li2CO3, LiAlO2, Li4SiO4, Li2SiO3, Li3PO4, Li2SO4, Li2TiO3, Li4Ti5O 12 , Li2Ti2O5, Li2ZrO3, LiNbO3, Li2MoO4, Li2WO4, and the like.

[0024] (Solid electrolyte) The solid electrolyte contained in the solid electrolyte layer preferably contains at least one solid electrolyte species selected from the group of solid electrolytes consisting of sulfide solid electrolytes, oxide solid electrolytes, and halide solid electrolytes.

[0025] As a sulfide solid electrolyte, it is preferable to contain sulfur (S) as the main component of the anion element, and in addition to S, it is also preferable to contain, for example, Li element, A element, and S element. The A element 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 halogen elements. Examples of the halogen element (X) include F, Cl, Br, I, etc. The composition of the sulfide solid electrolyte is not particularly limited, and examples include xLi2S·(100 - x)P2S5 (70 ≤ x ≤ 80), yLiI·zLiBr·(100 - y - z)(xLi2S·(1 - x)P2S5) (0.7 ≤ x ≤ 0.8, 0 ≤ y ≤ 30, 0 ≤ z ≤ 30).

[0026] The sulfide solid electrolyte may have a composition represented by the following general formula (1). Li 4-x Ge 1-x P x S4(0 < x < 1) ··· Formula (1) In Formula (1), at least a part of Ge may be substituted by at least one selected from the group consisting of Sb, Si, Sn, B, Al, Ga, In, Ti, Zr, V, and Nb. Also, at least a part of P may be substituted by at least one selected from the group consisting of Sb, Si, Sn, B, Al, Ga, In, Ti, Zr, V, and Nb. A part of Li may be substituted by at least one selected from the group consisting of Na, K, Mg, Ca, and Zn. A part of S may be substituted by a halogen. The halogen is at least one of F, Cl, Br, and I.

[0027] As the oxide solid electrolyte, it is preferable to contain oxygen (O) as the main component of the anion element. For example, it may contain Li, Q element (Q represents at least one of Nb, B, Al, Si, P, Ti, Zr, Mo, W, and S), and O. Examples of the oxide solid electrolyte include garnet-type solid electrolyte, perovskite-type solid electrolyte, NASICON-type solid electrolyte, Li-P-O-based solid electrolyte, Li-B-O-based solid electrolyte, etc. Examples of the garnet-type solid electrolyte include, for example, Li7La3Zr2O 12 、Li 7-x La3(Zr 2-x Nb x )O 12 (0≦x≦2), Li5La3Nb2O 12 etc. Examples of the perovskite-type solid electrolyte include, for example, (Li, La)TiO3, (Li, La)NbO3, (Li, Sr)(Ta, Zr)O3, etc. Examples of the NASICON-type solid electrolyte include, for example, Li(Al, Ti)(PO4)3, Li(Al, Ga)(PO4)3, etc. Examples of the Li-P-O-based solid electrolyte include Li3PO4, LIPON (a compound in which a part of O in Li3PO4 is substituted by N), and examples of the Li-B-O-based solid electrolyte include Li3BO3, a compound in which a part of O in Li3BO3 is substituted by C, etc.

[0028] 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 suitable. Specifically, Li 6-3z Y z X6 (X represents Cl or Br, and z satisfies 0 < z < 2), Li 6-(4-x)b (Ti 1-x Al x ) b F6 (0 < x < 1, 0 < b ≦ 1.5) is preferable. Among Li 6-3z Y z X6, Li3YX6 (X represents Cl or Br) is more preferable in terms of excellent lithium ion conductivity, and further, Li3YCl6 is preferable. Also, Li 6-(4-x)b (Ti 1-x Al x ) bF6 (0 < x < 1, 0 < b ≤ 1.5) is preferably included together with a solid electrolyte such as a sulfide solid electrolyte from the viewpoint of suppressing oxidative decomposition of the sulfide solid electrolyte, etc.

[0029] (Solid electrolyte layer) Examples of the solid electrolyte layer include electrolyte layers used in semi-solid batteries and all-solid batteries. The thickness of the solid electrolyte layer is not particularly limited and can be selected, for example, from the range of 1 μm to 30 μm. The type of solid electrolyte contained in the solid electrolyte layer is not particularly limited. For example, it may be selected from the solid electrolytes that may be contained in the above-described electrode layer and used. The solid electrolyte layer may be a single layer or a multilayer structure of two or more layers.

[0030] When the solid battery of the present disclosure contains a solid electrolyte, it may contain an electrolytic solution of less than 10% by mass with respect to the total amount of the electrolyte together with the solid electrolyte. When the battery of the present disclosure contains a solid electrolyte, the solid electrolyte may be a composite solid electrolyte containing an inorganic solid electrolyte and a polymer electrolyte. When the solid battery of the present disclosure contains an electrolytic solution as an electrolyte, the type of the electrolytic solution is not particularly limited, and a known electrolytic solution can be used. Specifically, examples of the electrolytic solution include liquids obtained by dissolving lithium salts such as LiPF6 and LiFSi in an organic solvent.

[0031] (Negative electrode layer) The negative electrode layer contains at least a negative electrode active material and may optionally contain an electrolyte, a conductive additive, and a binder. The negative electrode layer may also contain various other additives. Examples of negative electrode active materials include carbon materials, active materials containing Si elements, metallic lithium, lithium-containing alloys, metals or alloys that can be alloyed 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, mesocarbon microbeads (MCMB), and mesophase pitch carbon fiber (MCF). Graphite materials may be coated with metal or amorphous carbon. Examples of active materials containing Si elements include elemental silicon, silicon alloys (e.g., alloys of Si with one or more metals selected from the group consisting of Sn, Ti, Fe, Ni, Cu, Co, and Al), porous silicon, silicon clathrate compounds, and silicon oxides.

[0032] (Negative electrode current collector) Any of the commonly used negative electrode current collectors for batteries can be used as the negative electrode current collector. The negative electrode current collector may be in the form of foil, plate, mesh, perforated metal, or foam. The negative electrode current collector may be a metal foil or metal mesh, or a carbon sheet. The negative electrode current collector may consist of multiple foils or sheets. Examples of metals that make up 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 reduction resistance and avoiding alloying with lithium, the negative electrode current collector may contain at least one metal selected from Cu, Ni, and stainless steel.

[0033] The negative electrode current collector may have some kind of coating layer on its surface for purposes such as adjusting resistance. Alternatively, the negative electrode current collector may be a metal foil or a substrate on which the above-mentioned metal is plated or deposited. Furthermore, if the negative electrode current collector consists of multiple metal foils, some kind of layer may be present between these multiple metal foils. The thickness of the negative electrode current collector is not particularly limited. For example, it may be 0.1 μm or more, 1 μm or more, 1 mm or less, or 100 μm or less. For example, in a solid-state battery as shown in Figure 1, an Al foil (corresponding to the first negative electrode current collector 7B in Figure 1) having a Ni plating layer (corresponding to the first negative electrode current collector 7A in Figure 1) can be used as the negative electrode current collector. More specifically, for example, an Al foil with a thickness of 10 μm on which a 1 μm thick Ni plating layer is laminated can be used as the negative electrode current collector.

[0034] (Carbon coating layer) The carbon coating layer functions as an adhesive layer for bonding the negative electrode current collector to the negative electrode layer, and also as a conductive layer to ensure electrical conductivity between the negative electrode current collector and the negative electrode layer. Examples of carbon materials included in the carbon coating layer 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, mesocarbon microbeads (MCMB), and mesophase pitch carbon fiber (MCF).

[0035] (Exterior) The solid-state battery of this disclosure may further include an outer casing. The outer casing at least houses the electrode laminate described above. Examples of outer casings include laminate-type outer casings and case-type outer casings. A laminate-type outer casing may be formed from a laminate (laminate film) having a metal layer containing a metal such as aluminum and a heat-seal layer containing a resin that melts upon heating.

[0036] (Restraining member) The solid-state battery of this disclosure may further include a restraining member. The restraining member applies a restraining pressure in the thickness direction to the electrode stack described above. The restraining pressure applied in the thickness direction to the electrode stack may be, for example, 0.1 MPa or more, 1 MPa or more, or 5 MPa or more. The restraining pressure applied in the thickness direction to the electrode stack may be, for example, 100 MPa or less, 50 MPa or less, or 20 MPa or less.

[0037] <Method of manufacturing solid-state batteries> The method for manufacturing a solid-state battery according to the present disclosure includes the steps of forming a positive electrode layer and an insulating layer on at least one main surface of a positive electrode current collector, the insulating layer being in contact with the end of the positive electrode layer and being flush with the positive electrode layer, and forming a solid electrolyte layer on the positive electrode layer and the insulating layer such that its end overlaps the insulating layer. According to the method for manufacturing a solid-state battery according to the present disclosure, damage to the solid electrolyte layer can be prevented even when pressure is applied in the stacking direction of the positive electrode current collector, positive electrode layer and solid electrolyte layer. In particular, in the method for manufacturing a solid-state battery according to the present disclosure, it is preferable to densify the positive electrode layer by compressing the positive electrode layer and insulating layer in the stacking direction after forming the positive electrode layer and insulating layer on the main surface of the positive electrode current collector.

[0038] Next, in the method for manufacturing a solid-state battery according to the present disclosure, the negative electrode layer is formed such that, in a cross-sectional view along the stacking direction of the positive electrode current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, its edges overlap the solid electrolyte layer and the insulating layer.

[0039] Regarding the method for manufacturing a solid-state battery according to the present disclosure, taking the solid-state battery shown in Figure 1 as an example, first, a positive electrode layer 2 and an insulating layer 3 are formed on both 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 the insulating layer. Then, by sequentially forming a negative electrode layer 5, a carbon coating layer 6, and a negative electrode current collector 7 on the solid electrolyte layer 4, the solid-state battery shown in Figure 1 can be manufactured. At this time, it is preferable to form the positive electrode layer 2 and the insulating layer 3 on both main surfaces of the positive electrode current collector 1 and compress the positive electrode current collector 1 in the stacking direction X so as to sandwich it, thereby densifying the positive electrode layer 2 formed on both main surfaces of the positive electrode current collector 1. Then, the solid electrolyte layer 4 is formed after the positive electrode layer 2 has been densified. Alternatively, the positive electrode layer 2 and the solid electrolyte layer 4 can be densified simultaneously by compressing the positive electrode current collector 1 in the stacking direction X so as to sandwich it after the solid electrolyte layer 4 has been formed.

[0040] 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 the end of the negative electrode layer 5 on the positive electrode current collector tab side 1A overlaps with the solid electrolyte layer 4 and the insulating layer 3. Then, the carbon coat layer 6 in the laminate of the negative electrode current collector 7 and the carbon coat layer 6 is bonded to the negative electrode layer 5. This makes it possible to form the carbon coat layer 6 and the negative electrode current collector 7 on the negative electrode layer 5.

[0041] In the solid-state battery manufacturing method of this disclosure, the solid electrolyte layer 4 is formed such that its end face does not overlap with the positive electrode layer 2, but overlaps with the insulating layer 3. This prevents damage to the solid electrolyte layer 4, particularly damage near the end face of the solid electrolyte layer 4, even when pressure is applied to the solid-state battery in the stacking direction X. Furthermore, in the solid-state battery manufacturing method of this disclosure, the negative electrode layer 5 can be disposed after the positive electrode layer 2 has been densified, thus avoiding the application of large pressure to the negative electrode layer 5 in the stacking direction X.

[0042] <Another Embodiment 1> The solid-state battery of this disclosure is not limited to the configuration shown in Figure 1, and may have an adhesive layer between the positive electrode current collector, the positive electrode layer and the insulating layer. In this case as well, the positive electrode layer and the insulating layer are formed on at least one main surface of the positive electrode current collector, but a method can be employed in which an adhesive layer is formed on the one main surface of the positive electrode current collector, and the positive electrode layer and the insulating layer formed on the transfer member are transferred to the adhesive layer.

[0043] Specifically, 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, as shown in Figure 3. In the solid-state battery shown in Figure 3, the adhesive layer 9 is a single layer that covers the entire surface of both main surfaces of the positive electrode current collector 1, but it may also be formed in an island-like manner on parts of both main surfaces of the positive electrode current collector 1. In other words, the adhesive layer 9 may be a layer that covers the entire surface or in an island-like manner, as long as it has the function of bonding the positive electrode layer 2 and the insulating layer 3 to both main surfaces of the positive electrode current collector 1.

[0044] In particular, it is preferable that the adhesive layer 9 is conductive. If the adhesive layer 9 is conductive, an electrical connection between the positive electrode current collector 1 and the positive electrode layer 2 can be ensured even if the adhesive layer 9 is laminated as a single layer on the positive electrode current collector 1.

[0045] Furthermore, while the thickness of the adhesive layer 9 is not particularly limited, it 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 does not have conductivity, the positive electrode active material contained in the positive electrode layer 2 penetrates the adhesive layer 9, thereby ensuring an electrical connection between the positive electrode current collector 1 and the positive electrode layer 2.

[0046] The solid-state battery shown in Figure 3 is not particularly limited, but for example, as shown in Figure 4, a method can be applied in which a positive electrode layer 2, an insulating layer 3, and a transfer member 10 are formed, and the positive electrode layer 2 and insulating layer 3 are transferred to an adhesive layer 9 formed on a positive electrode current collector 1. Specifically, first, as shown in Figure 4(a), a positive electrode slurry containing positive electrode active material is applied to one main surface of the transfer member 10 to form the positive electrode layer 2. At this time, due to coating sagging of the positive electrode slurry applied to one main surface of the transfer member 10, the peripheral edge of the positive electrode layer 2 becomes an inclined surface. Then, as shown in Figure 4(b), the inclined surface caused by coating sagging in the positive electrode layer 2 is removed. Next, as shown in Figure 4(c), an insulating slurry containing insulating material is applied so as to contact the end face of the positive electrode layer 2. At this time, due to coating sagging of the insulating slurry, the peripheral edge of the insulating layer 3 becomes an inclined surface. Then, as shown in Figure 4(d), the inclined surface caused by coating sagging in the insulating layer 3 is removed. As described above, the positive electrode layer 2 and the insulating layer 3 can be formed on one main surface of the transfer member 10.

[0047] In the solid-state battery shown in Figure 3, by removing the inclined surfaces caused by coating sagging from the positive electrode layer 2 and the insulating layer 3, the usable area for the positive electrode layer 2 can be designed to be wider, thereby improving battery performance. Furthermore, in the solid-state battery shown in Figure 3, by removing the inclined surfaces caused by coating sagging from the insulating layer 3, the mechanical strength of the end of the insulating layer 3 on the positive electrode current collector tab side 1A can be improved. Specifically, as shown in Figure 5, the inclination angle α of the end face of the positive electrode layer 2 that is in contact with the insulating layer 3 and the inclination angle β of the end face of the insulating layer 3 opposite to the end face in contact with the positive electrode layer 2 are preferably in the range of ±10° with respect to the stacking direction X in the cross-sectional view, and more preferably in the range of ±5°. By setting these inclination angles α and β within this range, the usable area for the positive electrode layer 2 can be designed to be wider, thereby improving battery performance.

[0048] Incidentally, when transferring the positive electrode layer 2 and the insulating layer 3 to the adhesive layer 9 using the transfer member 10, as shown in Figure 4, instead of cutting off the inclined surfaces caused by coating sagging on both the positive electrode layer 2 and the insulating layer 3, it is also possible to cut off only the inclined surface of the insulating layer 3. In this case, as shown in Figure 6, in the cross-sectional view, the inclination angle of the end face of the insulating layer 3 opposite to the end face in contact with the positive electrode layer 2 is closer to 90° than the inclination angle of the end face of the positive electrode layer 2 in contact with the insulating layer 3. In this case, as shown in Figure 7(a), a positive electrode slurry containing positive electrode active material is applied to one main surface of the transfer member 10 to form the positive electrode layer 2. At this time, due to coating sagging of the positive electrode slurry applied to one main surface of the transfer member 10, the end of the positive electrode layer 2 becomes an inclined surface. Subsequently, as shown in Figure 7(b), an insulating slurry containing insulating material is applied so as to cover the inclined surface of the positive electrode layer 2. At this time, due to coating sagging of the insulating slurry, the end of the insulating layer 3 becomes an inclined surface. Subsequently, as shown in Figure 7(c), the inclined surface caused by coating sagging in the insulating layer 3 is removed. In this way, a positive electrode layer 2 having an inclined surface and an insulating layer 3 from which the inclined surface has been removed can be formed on one main surface of the transfer member 10.

[0049] In the solid-state battery shown in Figure 6, the mechanical strength of the end of the insulating layer 3 on the positive electrode current collector tab side 1A can be improved by removing the inclined surface caused by coating sagging in the insulating layer 3. Specifically, as shown in Figure 8, the inclination angle δ of the end face of the insulating layer 3 opposite to the end face in contact with the positive electrode layer 2 can be made closer to 90° than the inclination angle γ of the end face of the positive electrode layer 2 in contact with the insulating layer 3. This improves the mechanical strength of the end of the insulating layer 3 on the positive electrode current collector tab side 1A. <Types and uses of batteries> The type of solid-state battery is not particularly limited, but is typically a lithium-ion battery. Furthermore, the solid-state battery in this disclosure may be a primary battery or a secondary battery, but is preferably a secondary battery. This is because it can be repeatedly charged and discharged, making it useful, for example, as an in-vehicle battery. The solid-state battery may be a semi-solid-state battery having a gel layer containing an electrolyte and a polymer between the electrode and the solid electrolyte, or it may be an all-solid-state battery using a solid electrolyte. The solid electrolyte may contain less than 10% by mass of the electrolyte relative to the total amount of electrolyte. The solid-state battery is preferably an all-solid-state battery.

[0050] The applications of the battery disclosed herein are not particularly limited. Typical applications include power sources for vehicles, electronic equipment, and electrical storage systems. It may also be used as a power source for other mobile devices (e.g., railways, ships, aircraft), or as a power source for electrical products such as information processing devices. Among these, the battery disclosed herein is preferably used as a power source for vehicles, and more preferably as a power source for hybrid vehicles, plug-in hybrid vehicles, or electric vehicles. Examples of vehicles include electric four-wheeled vehicles, electric two-wheeled vehicles, gasoline-powered vehicles, and diesel-powered vehicles. Examples of electric four-wheeled vehicles include battery electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), and hybrid electric vehicles (HEVs). Examples of electric two-wheeled vehicles include electric motorcycles and electric-assist bicycles. [Explanation of symbols]

[0051] 1...Positive electrode current collector 2…Positive electrode layer 3…Insulating layer 4...Solid electrolyte layer 5…Negative electrode layer 5A…1st negative electrode layer 5B…Second negative electrode layer 6…Carbon coating layer 7…Negative electrode current collector 7A...1st negative electrode current collector 7B…Second negative electrode current collector 8…End insulation 9...Adhesive layer 10…Transfer material

Claims

1. Positive electrode current collector and A positive electrode layer is disposed on at least one main surface of the positive electrode current collector, An insulating layer is provided on one main surface of the positive electrode current collector, in contact with the end of the positive electrode layer, and arranged flush with the positive electrode layer. A solid-state battery comprising: a positive electrode layer and a solid electrolyte layer disposed on the insulating layer, with its end overlapping the insulating layer.

2. The solid battery according to claim 1, wherein the positive electrode current collector has a positive electrode current collector tab-side end connected to the positive electrode current collector tab, and the insulating layer and the positive electrode layer are arranged in this order from the positive electrode current collector tab-side end.

3. The solid battery according to claim 1, wherein an adhesive layer is provided between the positive electrode current collector, the positive electrode layer and the insulating layer.

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

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

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

7. The solid battery according to claim 1, wherein, in a cross-sectional view along the stacking direction of the positive electrode current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the inclination angle of the end face of the positive electrode layer in contact with the insulating layer and the inclination angle of the end face of the insulating layer opposite to the end face in contact with the positive electrode layer are within the range of ±10° with respect to the stacking direction.

8. The solid battery according to claim 1, wherein, in a cross-sectional view along the lamination direction of the positive electrode current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the angle of inclination of the end face of the insulating layer opposite to the end face in contact with the positive electrode layer is closer to 90° than the angle of inclination of the end face of the positive electrode layer in contact with the insulating layer.

9. A step of forming a positive electrode layer and an insulating layer that is in contact with the end of the positive electrode layer and is flush with the positive electrode layer on at least one main surface of the positive electrode current collector, A method for manufacturing a solid battery, comprising the step of forming a solid electrolyte layer on the positive electrode layer and the insulating layer such that its edges overlap the insulating layer.

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

11. The method for manufacturing a solid battery according to claim 9, wherein in the step of forming the positive electrode layer and the insulating layer, an adhesive layer is formed on one main surface of the positive electrode current collector, and the positive electrode layer and the insulating layer formed on the transfer member are transferred to the adhesive layer.

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

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

14. A method for manufacturing a solid battery according to claim 11, comprising: coating the transfer member with a positive electrode slurry containing a positive electrode active material; then cutting off the inclined surface of the peripheral edge of the coated positive electrode slurry; coating the positive electrode slurry containing an insulating material in contact with the peripheral edge of the positive electrode slurry; and then cutting off the inclined surface of the peripheral edge of the coated insulating slurry.

15. A method for manufacturing a solid battery according to claim 14, wherein, in a cross-sectional view along the stacking direction of the positive electrode current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the inclination angle of the end face of the positive electrode layer that is in contact with the insulating layer and the inclination angle of the end face of the insulating layer opposite to the end face that is in contact with the positive electrode layer are within the range of ±10° with respect to the stacking direction.

16. A method for manufacturing a solid battery according to claim 11, comprising: coating the transfer member with a positive electrode slurry containing a positive electrode active material; then coating the transfer member with an insulating slurry containing an insulating material so as to cover the inclined surface of the peripheral edge of the coated positive electrode slurry; and then cutting off the inclined surface of the peripheral edge of the coated insulating slurry.

17. A method for manufacturing a solid battery according to claim 16, wherein, in a cross-sectional view along the lamination direction of the positive electrode current collector, the positive electrode layer, the insulating layer, and the solid electrolyte layer, the angle of inclination of the end face of the insulating layer opposite to the end face in contact with the positive electrode layer is closer to 90° than the angle of inclination of the end face of the positive electrode layer in contact with the insulating layer.

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