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 invention comprises a positive electrode current collector, a positive electrode layer disposed on at least one main surface of the positive electrode current collector, a solid electrolyte layer disposed on the positive electrode layer, and an insulating layer in contact with the end of the solid electrolyte layer, wherein the end of the insulating layer opposite to the end in contact with the solid electrolyte layer is located in a position that overlaps with the positive electrode 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 electrolyte sheet for use in a solid electrolyte secondary battery, comprising a plate-shaped base containing a solid electrolyte and a plate-shaped reinforcing portion superimposed on the base on the outside of the base. Here, the reinforcing portion is made of an insulating material. Patent Document 1 states that the rigidity near the periphery can be increased, thereby reducing the risk of damage to the periphery of the solid electrolyte sheet.

[0004] Furthermore, Patent Document 2 discloses a solid-state battery in which a positive electrode layer, a solid electrolyte layer, and a negative electrode layer are stacked in this order, the outer edge of the solid electrolyte layer is outside the positive electrode layer and the negative electrode layer, and the portion of the solid electrolyte layer that does not overlap with the positive electrode layer and the negative electrode layer has a lower solid electrolyte content than the overlapping portion. According to Patent Document 2, reducing the solid electrolyte content in the non-overlapping portion can reduce production costs and suppress short circuits. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2024-86926 [Patent Document 2] Japanese Patent Publication No. 2023-107428 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, when pressure is applied in the stacking direction to a structure in which a positive electrode layer, a solid electrolyte layer, and a negative electrode layer are sequentially stacked on a positive electrode current collector, there is a risk that the edges of the solid electrolyte layer may be damaged. 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, a solid electrolyte layer disposed on the positive electrode layer, and an insulating layer in contact with the end of the solid electrolyte layer, wherein the end of the insulating layer opposite to the end in contact with the solid electrolyte layer is positioned to overlap with the positive electrode layer. <2> The system further comprises a negative electrode layer disposed on the solid electrolyte layer and the insulating layer, wherein the end of the negative electrode layer is located in a position overlapping with the insulating layer. <1> Solid-state batteries as described above. <3> The positive electrode current collector has a positive electrode current collector tab-side end connected to the positive electrode current collector tab, and on the positive electrode layer, the insulating layer and the solid electrolyte layer are arranged in this order from the positive electrode current collector tab-side end. <1> or <2> Solid-state batteries as described above. <4> An adhesive layer is provided between the positive electrode current collector and the positive electrode layer. <1> ~ <3> A solid battery as described in any one of the following. <5> The adhesive layer is conductive. <4> Solid-state batteries as described above. <6> The adhesive layer has a thickness of 0.5 μm to 1.5 μm. <4> Solid-state batteries as described above. <7> In a cross-sectional view along the lamination direction of the positive electrode current collector, the positive electrode layer, the solid electrolyte layer, and the insulating layer, the inclination angle of the end face of the solid electrolyte 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 solid electrolyte layer are within a range of ±10° with respect to the lamination direction. <1> ~ <6> A solid battery as described in any one of the following. <8> A method for manufacturing a solid-state battery, comprising the steps of forming a positive electrode layer on at least one main surface of a positive electrode current collector, and forming a solid electrolyte layer and an insulating layer in contact with the end of the solid electrolyte layer on the positive electrode layer, wherein the end of the insulating layer opposite to the end in contact with the solid electrolyte layer is positioned to overlap with the positive electrode layer. <9> The process further includes the step of forming a negative electrode layer such that its end overlaps the insulating layer. <8> A method for manufacturing a solid-state battery as described above. <10> In the step of forming the positive electrode layer, an adhesive layer is formed on one main surface of the positive electrode current collector, and the positive electrode layer formed on the transfer member is transferred to the adhesive layer. <8> or <9> A method for manufacturing a solid-state battery as described above. <11> The adhesive layer is conductive. <10> A method for manufacturing a solid-state battery as described above. <12> The adhesive layer has a thickness of 0.5 μm to 1.5 μm. <10> A method for manufacturing a solid-state battery as described above. <13> A positive electrode slurry containing a positive electrode active material is applied to the transfer member, and then the inclined surface of the peripheral edge of the applied positive electrode slurry is cut off. <10> A method for manufacturing a solid-state battery as described above. <14> In a cross-sectional view along the lamination direction of the positive electrode current collector, the positive electrode layer, the solid electrolyte layer, and the insulating layer, the inclination angle of the end face of the solid electrolyte 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 solid electrolyte layer are within a range of ±10° with respect to the lamination direction. <8> ~ <13> A method for manufacturing a solid battery as described in any one of the following. [Effects 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 the solid-state battery in a plan view seen from above is cut by a plane parallel to the first axis direction. [Figure 3] It is a cross-sectional view of a main part showing a process of forming a positive electrode layer on a transfer member. [Figure 4] It is a cross-sectional view of a main part showing a process of forming a solid electrolyte layer and an insulating layer on a transfer member. [Figure 5] It is a cross-sectional view of a main part showing the inclination angle of each end face of the solid electrolyte layer and the insulating layer formed on the transfer member. [Figure 6] It is a cross-sectional view of a main part of a solid-state battery shown as another embodiment of the present disclosure.

Embodiments for Carrying Out the Invention

[0010] In the present disclosure, a numerical range indicated using “~” means a range including the numerical values described before and after “~” as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other stepwise descriptions. In the numerical ranges described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples. In the present disclosure, the term “step” includes not only an independent step but also the case where it cannot be clearly distinguished from other steps, as long as the intended purpose of the step is achieved. In the present 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, a solid electrolyte layer disposed on the positive electrode layer, and an insulating layer in contact with the end of the solid electrolyte layer, wherein the end of the insulating layer opposite to the end in contact with the solid electrolyte layer is located on the positive electrode layer. In the solid-state battery of this disclosure, even when pressure is applied in the stacking direction of the positive electrode current collector, positive electrode layer, and 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), the insulating layer protects the solid electrolyte layer and prevents damage to the solid electrolyte layer. If the solid electrolyte layer is damaged, it is conceivable that the battery performance may deteriorate due to problems such as further crack propagation from the damaged part, or lithium deposition due to non-uniform reactions at the damaged part. The solid-state battery of this disclosure suppresses the occurrence of these problems and maintains excellent battery performance.

[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 disposed on both main surfaces of the positive electrode current collector 1, an insulating layer 3 and a solid electrolyte layer 4 disposed on the positive electrode layer 2, 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 solid electrolyte layer 4 on the positive electrode layer 2 are arranged in this order starting from the positive electrode current collector tab-side end 1A. In addition, 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, an insulating layer 3 is provided at one end of the solid electrolyte layer 4, thereby protecting that end. As a result, in the solid-state battery shown in Figure 1, even when pressure is applied in the stacking direction of the positive electrode current collector 1, positive electrode layer 2, and solid electrolyte layer 4 (direction X in Figure 1), damage to the solid electrolyte layer 4, particularly damage to the end of the solid electrolyte layer 4, can be prevented.

[0016] Furthermore, in the solid-state battery of this disclosure, the end of the negative electrode layer 5, which is arranged on the solid electrolyte layer 4 and the insulating layer 3, is positioned to overlap with the insulating layer 3. That is, 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, the end of the negative electrode layer 5 on the positive electrode current collector tab side 1A is positioned to overlap with the insulating layer 3. As a result, in the solid-state battery of this disclosure, the end of the solid electrolyte layer 4 can be protected by the negative electrode layer 5, and damage to the end of the solid electrolyte layer 4 can be further prevented even when pressure is applied in the direction X in Figure 1. Moreover, in the solid-state battery shown in Figure 1, the solid electrolyte layer 4 and the insulating layer 3 are formed flush with the main surface of the positive electrode layer 2. That is, the solid electrolyte layer 4 and the insulating layer 3 are in contact at one end surface, and the main surface of the solid electrolyte layer 4 and the main surface of the insulating layer 3 form the same plane. As a result, in the solid-state battery of this disclosure, the edges of the solid electrolyte layer 4 can be more reliably protected by the negative electrode layer 5, and damage to the edges of the solid electrolyte layer 4 can be more effectively prevented even when pressure is applied in the direction X in Figure 1.

[0017] The cross-sectional view along the stacking direction X mentioned above refers to the view of a cross-section obtained by cutting a solid battery along the stacking direction X of the battery stacking structure, and more specifically, the view of a cross-section passing through the positive electrode current collector tab end 1A and the end opposite to the positive electrode current collector tab end 1A. More specifically, if the solid battery shown in Figure 1 is a prismatic battery, the cross-sectional view along the stacking direction X can be the cross-sectional view obtained by cutting the rectangle, viewed from above in plan, along 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 end 1A and the end insulation portion 8.

[0018] Furthermore, the solid-state battery shown in Figure 1 includes an adhesive layer 9 between the positive electrode current collector 1 and the positive electrode layer 2. In this case, the adhesive layer 9 is formed on one main surface of the positive electrode current collector 1, and the positive electrode layer 2 can be arranged by transferring the positive electrode layer 2, which is formed on a transfer member, to the adhesive layer 9, as will be described in detail later. In the solid-state battery shown in Figure 1, the adhesive layer 9 is formed as a single layer so as to cover 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 adhering the positive electrode layer 2 to both main surfaces of the positive electrode current collector 1.

[0019] 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.

[0020] 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.

[0021] Furthermore, in the solid-state battery shown in Figure 1, as will be described in detail later, when the solid electrolyte layer 4 and the insulating layer 3 are manufactured by coating them with slurry, inclined surfaces are formed due to coating sagging, but it is preferable to remove these inclined surfaces. This allows for a wider area to be designed as the solid electrolyte layer 4, thereby improving battery performance. Also, in the solid-state battery shown in Figure 1, removing the inclined surfaces caused by coating sagging in the insulating layer 3 improves the mechanical strength of the end of the insulating layer 3 on the positive electrode current collector tab side end 1A. Specifically, the inclination angle α of the end face of the solid electrolyte layer 4 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 that is in contact with the solid electrolyte layer 4 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, a wider area to be designed as the solid electrolyte layer 4 can be designed, thereby improving battery performance.

[0022] In the solid-state battery configured as described above, the end of the insulating layer 3, which is placed on the positive electrode layer 2, opposite to the end that contacts the solid electrolyte layer 4, is positioned to overlap with the positive electrode layer 2. As a result, even when pressure is applied to the solid-state battery in the stacking direction X, the insulating layer 3 protects the solid electrolyte layer 4, preventing damage to the solid electrolyte layer 4, especially damage near the end face of the solid electrolyte layer 4. If the solid electrolyte layer 4 is damaged, problems such as further crack propagation from the damaged area and lithium deposition due to uneven reactions at the damaged area can lead to a deterioration in battery performance. The solid-state battery shown in Figure 1 can suppress the occurrence of these problems and maintain excellent battery performance.

[0023] Here, applying pressure in the stacking direction X means applying pressure in a direction that sandwiches the positive electrode current collector 1, positive electrode layer 2, insulating layer 3 and solid electrolyte layer 4, negative electrode layer 5 and negative electrode current collector 7. Although not shown, the solid battery may further include a restraining member that restrains these positive electrode layer 2, insulating layer 3, solid electrolyte layer 4, negative electrode layer 5 and 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 be, for example, 100 MPa or less, 50 MPa or less, or 20 MPa or less. Even if the above-mentioned pressure is applied by the restraining member, the solid 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.

[0024] 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 is placed on the main surface of the positive electrode current collector 1, and then the positive electrode layer 2 can be densified by compressing it in the stacking direction. Subsequently, the insulating layer 3, the solid electrolyte layer 4, and the negative electrode layer 5 are sequentially placed on the positive electrode layer 2. In other words, when manufacturing the solid-state battery, the negative electrode layer 5 can be placed 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.

[0025] 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.

[0026] <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.

[0027] (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), lithium titanate, lithium metal phosphate (such as LiMPO4, where M is one or more selected from Fe, Mn, Co, and Ni), and various other lithium-containing oxides may be used. In particular, when the cathode active material contains a lithium-containing oxide that includes at least Li, at least one of Ni, Co, and Mn, and O as constituent elements, a higher effect can be expected. As the cathode active material, only one type may be used alone, or two or more types may be combined and used.

[0028] The shape of the cathode active material may be a common shape as the cathode active material of the battery. The cathode active material may be, for example, particulate. The cathode active material may be solid, hollow, have voids, or be porous. The cathode active material may be primary particles or secondary particles formed by aggregation of a plurality of primary particles. Also, a protective layer containing an ion-conductive oxide may be formed on the surface of the cathode active material. This makes it easier to suppress the reaction between the cathode active material and a sulfide (such as 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.

[0029] (Solid electrolyte) As the solid electrolyte contained in the solid electrolyte layer, it is preferable to include at least one solid electrolyte type selected from the group of solid electrolytes consisting of sulfide solid electrolytes, oxide solid electrolytes, and halide solid electrolytes.

[0030] 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 thereof 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).

[0031] 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 with 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 with 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 with at least one selected from the group consisting of Na, K, Mg, Ca, and Zn. A part of S may be substituted with a halogen. The halogen is at least one of F, Cl, Br, and I.

[0032] 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 part of O in Li3PO4 is replaced by N), and examples of the Li-B-O-based solid electrolyte include Li3BO3, a compound in which part of O in Li3BO3 is replaced by C, etc.

[0033] 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 and the like.

[0034] (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 electrode layer described above and used. The solid electrolyte layer may be a single layer or a multilayer structure of two or more layers.

[0035] 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.

[0036] (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.

[0037] (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.

[0038] 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.

[0039] (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).

[0040] (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.

[0041] (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.

[0042] <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 on at least one main surface of a positive electrode current collector, and forming a solid electrolyte layer and an insulating layer in contact with the end of the solid electrolyte layer on the positive electrode layer, wherein the end of the insulating layer opposite to the end in contact with the solid electrolyte layer is positioned to overlap with the positive electrode layer. According to the method for manufacturing a solid-state battery according to the present disclosure, even when pressure is applied in the stacking direction of the positive electrode current collector, positive electrode layer and solid electrolyte layer, the insulating layer can protect the solid electrolyte layer and prevent damage to the solid electrolyte layer.

[0043] Furthermore, the method for manufacturing a solid-state battery of the present disclosure further includes a step of forming a negative electrode layer such that its end overlaps the insulating layer. In the method for manufacturing a solid-state battery of the present disclosure, the negative electrode layer is formed such that its end overlaps 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.

[0044] 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 is formed on both main surfaces of the positive electrode current collector 1. Then, an insulating layer 3 and a solid electrolyte layer 4 are formed on the positive electrode layer 2, with their ends overlapping the positive electrode layer 2. 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.

[0045] The manufacturing method for a solid-state battery according to this disclosure is not particularly limited, but as shown in Figure 3, the positive electrode layer 2 can be arranged by forming the positive electrode layer 2 on a transfer member 10 and transferring the positive electrode layer 2 to an adhesive layer 9 formed on a positive electrode current collector 1. Specifically, first, as shown in Figure 3(a), a positive electrode slurry containing positive electrode active material is coated onto 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 coated onto one main surface of the transfer member 10, the peripheral edge of the positive electrode layer 2 becomes an inclined surface. Subsequently, although not shown, it is preferable to densify the positive electrode layer 2 formed on the main surface of the transfer member 10 by compressing it so as to sandwich the transfer member 10. Then, as shown in Figure 3(b), the inclined surface caused by coating sagging in the positive electrode layer 2 is cut off. In this way, the positive electrode layer 2 can be formed on one main surface of the transfer member 10.

[0046] Furthermore, the method for manufacturing a solid-state battery according to this disclosure is not particularly limited, but as shown in Figure 4, the insulating layer 3 and the solid electrolyte layer 4 can be arranged by forming the insulating layer 3 and the solid electrolyte layer 4 on a transfer member 10 and transferring the insulating layer 3 and the solid electrolyte layer 4 onto the positive electrode layer 2. Specifically, first, as shown in Figure 4(a), a solid electrolyte slurry containing a solid electrolyte is applied to one main surface of the transfer member 10 to form the solid electrolyte layer 4. At this time, due to coating sagging of the solid electrolyte slurry applied to one main surface of the transfer member 10, the peripheral edge of the solid electrolyte layer 4 becomes an inclined surface. Then, as shown in Figure 4(b), the inclined surface caused by coating sagging in the solid electrolyte layer 4 is removed. Next, as shown in Figure 4(c), an insulating slurry containing an insulating material is applied so as to contact the end face of the solid electrolyte layer 4. 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. Subsequently, although not shown in the diagram, it is preferable to compress the transfer member 10 so as to sandwich it, thereby densifying the solid electrolyte layer 4 formed on the main surface of the transfer member 10. In this way, the insulating layer 3 and the solid electrolyte layer 4 can be formed on one main surface of the transfer member 10.

[0047] By removing the inclined surfaces caused by coating sagging in the insulating layer 3 and the solid electrolyte layer 4, the usable area for the solid electrolyte layer 4 can be designed to be wider, thereby improving battery performance. Furthermore, by removing the inclined surfaces caused by coating sagging in 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 solid electrolyte layer 4 that is in contact with the insulating layer 3 and the inclination angle β of the end face of the insulating layer 3 that is opposite to the end face that is in contact with the solid electrolyte layer 4 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 solid electrolyte layer 4 can be designed to be wider, thereby improving battery performance.

[0048] Subsequently, the negative electrode layer 5 is formed on the insulating layer 3 and the solid electrolyte layer 4 so that its edges overlap with 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 allows the carbon coat layer 6 and the negative electrode current collector 7 to be formed on the negative electrode layer 5.

[0049] According to the manufacturing method of the solid-state battery of this disclosure, the insulating layer 3 and the solid electrolyte layer 4 are arranged such that the end of the insulating layer 3 opposite to the end of the insulating layer 3 that contacts the solid electrolyte layer 4 overlaps with the positive electrode layer 2. According to the manufacturing method of the solid-state battery of this disclosure, even if pressure is applied in the stacking direction of the positive electrode current collector 1, the positive electrode layer 2, and the solid electrolyte layer 4, the insulating layer 3 can protect the solid electrolyte layer 4, and damage to the solid electrolyte layer 4, especially damage near the end face of the solid electrolyte layer 4, can be prevented. Furthermore, according to the manufacturing method of the solid-state battery of this disclosure, the negative electrode layer 5 can be arranged after the positive electrode layer 2 has been densified, so that a large pressure is not applied to the negative electrode layer 5 in the stacking direction X.

[0050] <Another Embodiment 1> The solid-state battery of this disclosure is not limited to the configuration shown in Figure 1, and may have a configuration without an adhesive layer 9 between the positive electrode current collector 1 and the positive electrode layer 2. That is, as shown in Figure 6, the positive electrode layer 2 may be disposed on at least one main surface of the positive electrode current collector 1. In this case, the positive electrode layer 2 is formed by coating the positive electrode slurry containing the positive electrode active material onto at least one main surface of the positive electrode current collector 1 and drying it. At this time, due to the coating runout of the positive electrode slurry, the peripheral edge of the positive electrode layer 2 becomes an inclined surface.

[0051] Subsequently, by arranging the insulating layer 3 and the solid electrolyte layer 4 on the positive electrode layer 2 using the method shown in Figure 4, and then arranging the negative electrode layer 5, carbon coating layer 6, and negative electrode current collector 7, a solid-state battery as shown in Figure 6 can be manufactured. In the solid-state battery shown in Figure 6, the end of the insulating layer 3 arranged on the positive electrode layer 2 that is opposite to the end in contact with the solid electrolyte layer 4 is positioned to overlap with the positive electrode layer 2. As a result, even if pressure is applied to the solid-state battery in the stacking direction X, the insulating layer 3 protects the solid electrolyte layer 4, preventing damage to the solid electrolyte layer 4, especially damage near the end face of the solid electrolyte layer 4. If the solid electrolyte layer 4 is damaged, it is conceivable that battery performance may deteriorate due to problems such as further crack propagation from the damaged area and lithium deposition due to uneven reactions at the damaged area. The solid-state battery shown in Figure 6 can suppress the occurrence of these problems and maintain excellent battery performance.

[0052] Furthermore, in the solid-state battery shown in Figure 6, 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, the positive electrode layer 2 can be densified by first placing the positive electrode layer 2 on the main surface of the positive electrode current collector 1 and then compressing it in the stacking direction. Subsequently, the insulating layer 3, the solid electrolyte layer 4, and the negative electrode layer 5 are sequentially placed on the positive electrode layer 2. In other words, when manufacturing the solid-state battery, the negative electrode layer 5 can be placed 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. <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.

[0053] 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]

[0054] 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, A solid electrolyte layer disposed on the positive electrode layer and an insulating layer in contact with the end of the solid electrolyte layer, A solid-state battery comprising the above, wherein the end of the insulating layer opposite to the end in contact with the solid electrolyte layer is located in a position that overlaps with the positive electrode layer.

2. The solid battery according to claim 1, further comprising a negative electrode layer disposed on the solid electrolyte layer and the insulating layer, wherein the end of the negative electrode layer is located in a position overlapping with the insulating layer.

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

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

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

6. The solid battery according to claim 4, wherein the adhesive layer has a thickness of 0.5 μm to 1.5 μm.

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 solid electrolyte layer, and the insulating layer, the inclination angle of the end face of the solid electrolyte 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 solid electrolyte layer are within the range of ±10° with respect to the stacking direction.

8. A step of forming a positive electrode layer on at least one main surface of a positive electrode current collector, A step of forming a solid electrolyte layer and an insulating layer in contact with the end of the solid electrolyte layer on the positive electrode layer. A method for manufacturing a solid battery, comprising: a part of the insulating layer, wherein the end of the insulating layer opposite to the end in contact with the solid electrolyte layer is positioned to overlap with the positive electrode layer.

9. The method for manufacturing a solid battery according to claim 8, further comprising the step of forming a negative electrode layer such that its end overlaps the insulating layer.

10. The method for manufacturing a solid battery according to claim 8, wherein in the step of forming the positive electrode layer, an adhesive layer is formed on one main surface of the positive electrode current collector, and the positive electrode layer formed on the transfer member is transferred to the adhesive layer.

11. The method for manufacturing a solid battery according to claim 10, wherein the adhesive layer is conductive.

12. The method for manufacturing a solid battery according to claim 10, wherein the adhesive layer has a thickness of 0.5 μm to 1.5 μm.

13. A method for manufacturing a solid battery according to claim 10, comprising coating the transfer member with a positive electrode slurry containing a positive electrode active material, and then cutting off the inclined surface of the peripheral edge of the coated positive electrode slurry.

14. A method for manufacturing a solid battery according to claim 8, wherein, in a cross-sectional view along the stacking direction of the positive electrode current collector, the positive electrode layer, the solid electrolyte layer, and the insulating layer, the inclination angle of the end face of the solid electrolyte 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 solid electrolyte layer are within the range of ±10° with respect to the stacking direction.

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