All solid state battery

Abstract

To provide an all-solid battery capable of improving reliability in a structure.SOLUTION: In an all-solid battery, a plurality of unit cells is laminated, in which each unit cell comprises: a second collector layer; a third active material layer; a first solid electrolyte layer; a first active material layer; a first collector layer; a second active material layer; a second solid electrolyte layer; a fourth active material layer; and a third collector layer in this order. In each unit cell, at least the first collector layer constructs an extension part so as to be extended to an external side from the third active material layer and the fourth active material layer. A protective layer is continuously provided over one side surface, a side surface, and the other side surface of the extension part. In at least one unit cell, a buffer material is arranged in at least one of between an end part of the one side surface of the protective layer and the second collector layer, and between the end part of the other side surface of the protective layer and the third collector layer.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present application relates to an all-solid-state battery. [Background technology]

[0002] Patent Document 1 discloses a technology for preventing damage to a secondary battery caused by movement of the protective member due to contraction of the exterior body during decompression treatment in battery manufacture, in a secondary battery having an internal protective member that restricts deformation of the exterior body due to changes in internal pressure and prevents cracking of the exterior body welded parts.

[0003] Specifically, the document discloses a secondary battery including an electrode body having a terminal connection part in which multiple layers of current collecting foils are joined to each other, an exterior body composed of a pair of laminate films facing each other across the electrode body, with a welding part where the pair of laminate films are welded formed on the outer periphery, and a plate-shaped conductive member extending along the width direction, one end of which is connected to the terminal connection part and the other end of which is exposed to the outside of the exterior body, the secondary battery further including a terminal insertion hole through which the electrode terminal is inserted, a protective member disposed between the side edge part of the exterior body in the width direction and the electrode body, which restricts the contraction deformation of the exterior body toward the center in the width direction, and a movement restriction means for restricting the movement of the protective member toward the center in the width direction. The technology of Patent Document 1 includes a movement restriction means for restricting the movement of the protective member, thereby preventing contact between the protective member and the electrode body due to a depressurization process or the like, and preventing damage to the electrode body by the protective member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-184518 A Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, all-solid-state batteries have been proposed in which the area of ​​the negative electrode is larger than that of the positive electrode. In such all-solid-state batteries, the negative electrode is formed to extend in the width direction in the cross section in the stacking direction. Therefore, there is a problem of the negative electrode active material layer slipping off or short circuiting caused by contact between the extending negative electrode part (extension part) and the positive electrode current collector. In order to prevent such problems, a technology for covering the extension part with a protective layer has been proposed.

[0006] However, due to external pressure or decompression treatment during battery manufacturing, the ends of the current collector and the protective layer come into contact with each other, which may cause stress to concentrate on the current collector and break the current collector. In addition, due to stress concentration caused by the contact between the ends of the current collector and the protective layer, the protective layer and its internal extension may be damaged, which may cause a short circuit.

[0007] The technology of Patent Document 1 does not pay attention to such stress concentration. Therefore, there has been a demand for a technology that solves the above problems and further improves the reliability of all-solid-state batteries.

[0008] In view of the above circumstances, an object of the present application is to provide an all-solid-state battery capable of improving the structural reliability. [Means for solving the problem]

[0009] As one means for solving the above-mentioned problems, the present disclosure provides an all-solid-state battery formed by stacking a plurality of unit cells each including a first current collector layer, a first active material layer laminated on one surface of the first current collector layer, a second active material layer laminated on the other surface of the first current collector layer, a first solid electrolyte layer laminated on one surface of the first active material layer, a second solid electrolyte layer laminated on the other surface of the second active material layer, a third active material layer laminated on one surface of the first solid electrolyte layer, a fourth active material layer laminated on the other surface of the second solid electrolyte layer, a second current collector layer laminated on one surface of the third active material layer, and a third current collector layer laminated on the other surface of the fourth active material layer, or when the first active material layer and the second active material layer are negative electrode active material layers, the third active material layer and the fourth active material layer are positive electrode active material layers, and when the first active material layer and the second active material layer are positive electrode active material layers, the third active material layer and the fourth active material layer are negative electrode active material layers; in the unit batteries, at least the first current collector layer extends outward beyond the third active material layer and the fourth active material layer to form an extension portion, and a protective layer is continuously provided over one side surface of the extension portion, a side surface of the extension portion, and the other side surface of the extension portion; and in at least one unit battery, a buffer material is disposed at least either between an outer end of the one side surface of the protective layer and the second current collector layer or between an outer end of the other side surface of the protective layer in the width direction and the third current collector layer. Effect of the Invention

[0010] The all-solid-state battery of the present disclosure is provided with a cushioning material at a predetermined position, which can improve the structural reliability of the all-solid-state battery. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a plan view of a unit battery 100. [Diagram 2] 2 is a cross-sectional view of the unit battery 100 taken along line AA in FIG. 1. [Diagram 3]13A and 13B are diagrams for explaining cushioning materials 61 and 62 which are other embodiments of the cushioning material. [Figure 4] 1 is a diagram for explaining an example of an arrangement mode of a cushioning material 60 in an all-solid-state battery 1000. FIG. [Diagram 5] 1 is a diagram for explaining an example of an arrangement mode of a cushioning material 60 in an all-solid-state battery 1000. FIG. [Figure 6] 1 is a diagram for explaining an example of an arrangement mode of a cushioning material 60 in an all-solid-state battery 1000. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] [All-solid-state battery 1000] Hereinafter, the all-solid-state battery of the present disclosure will be described with reference to an all-solid-state battery 1000 as one embodiment.

[0013] An all-solid-state battery 1000 is formed by stacking a plurality of unit batteries 100. Fig. 1 shows a plan view of the unit battery 100 observed from above in the stacking direction. Fig. 2 shows a cross-sectional view of the unit battery 100 cut along line AA in Fig. 1. Here, the top-to-bottom direction of the paper in Fig. 2 may be referred to as the stacking direction, the left-to-right direction of the paper as the width direction, and the back-to-front direction of the paper as the depth direction.

[0014] <100 unit batteries> The unit battery 100 includes a first current collector layer 11, a first active material layer 21 laminated on one surface of the first current collector layer 11, a second active material layer 22 laminated on the other surface of the first current collector layer 11, a first solid electrolyte layer 31 laminated on one surface of the first active material layer 21, a second solid electrolyte layer 32 laminated on the other surface of the second active material layer 22, a third active material layer 23 laminated on one surface of the first solid electrolyte layer 31, a fourth active material layer 24 laminated on the other surface of the second solid electrolyte layer 32, a second current collector layer 12 laminated on one surface of the third active material layer 23, and a third current collector layer 13 laminated on the other surface of the fourth active material layer 24.

[0015] Here, the first active material layer 21 and the second active material layer 22 are either a negative electrode active material layer or a positive electrode active material layer, and when the first active material layer 21 and the second active material layer 22 are negative electrode active material layers, the third active material layer 23 and the fourth active material layer 24 are positive electrode active material layers, and when the first active material layer 21 and the second active material layer 22 are positive electrode active material layers, the third active material layer 23 and the fourth active material layer 24 are negative electrode active material layers.

[0016] In the unit battery 100, at least the first current collector layer 11 extends outward beyond the third active material layer 23 and the fourth active material layer 24 to form an extension portion 40, and a protective layer 50 is continuously provided over one surface of the extension portion 40, the side surface of the extension portion 40, and the other surface of the extension portion 40. In the unit battery 100, a buffer material 60 is disposed at least either between an outer end 51 in the width direction of one surface of the protective layer 50 and the second current collector layer 12, or between an outer end 52 in the width direction of the other surface of the protective layer 50 and the third current collector layer 12.

[0017] (First current collector layer 11) The first current collector layer 11 may be made of a metal foil, a metal mesh, or the like. A metal foil is particularly preferred. Examples of metals constituting the first current collector layer 11 include Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, stainless steel, and the like. Cu is particularly preferred. The first current collector layer 11 may have some kind of coating layer (e.g., a carbon coating layer) on its surface for adjusting resistance. The first current collector layer 11 may be made of a plurality of layers. For example, the first current collector layer 11 may be made of a plurality of metal foils stacked together. The thickness of the first current collector layer 11 (the total thickness when the first current collector layer 11 is made of a plurality of layers; the same applies to other layers) is not particularly limited. For example, it is preferably 0.1 μm or more and 1 mm or less, and more preferably 1 μm or more and 100 μm or less. When the first active material layer 21 and the second active material layer 22 described later are negative electrode active material layers, the first current collector layer 11 functions as a negative electrode current collector layer. On the other hand, when the first active material layer 21 and the second active material layer 22 are positive electrode active material layers, the first current collector layer 11 functions as a positive electrode current collector layer.

[0018] (First active material layer 21 and second active material layer 22) In the unit battery 100, a first active material layer 21 is laminated on one side surface of the first current collector layer 11, and a second active material layer 22 is laminated on the other side surface of the first current collector layer 11. The first active material layer 21 may be composed of a plurality of layers. For example, an active material layer may be laminated on the surface of one active material layer, and the first active material layer 21 may be composed of the plurality of layers as a whole. The second active material layer 22 may also be composed of a plurality of layers. The first active material layer 21 and the second active material layer 22 are either a negative electrode active material layer or a positive electrode active material layer. In particular, it is preferable that they are negative electrode active material layers. The first active material layer 21 and the second active material layer 22 may be layers containing the same type of material or layers containing different materials. It is preferable that they are layers containing the same type of material. Hereinafter, the negative electrode active material layer will be described.

[0019] The negative electrode active material layer is a layer containing at least an active material. In addition to the active material, the negative electrode active material layer can optionally contain a solid electrolyte, a binder, a conductive assistant, and the like. The active material may be a known active material. Among known active materials, two materials having different potentials (charge / discharge potentials) at which a predetermined ion is absorbed and released can be selected, and the material showing a more noble potential can be used as the positive electrode active material described below, and the material showing a less noble potential can be used as the negative electrode active material. For example, in the case of constructing a lithium ion battery, silicon-based active materials such as Si, Si alloys, and silicon oxide; carbon-based active materials such as graphite and hard carbon; various oxide-based active materials such as lithium titanate; metallic lithium, lithium alloys, and the like can be used as the negative electrode active material. The solid electrolyte that can be contained in the negative electrode active material layer is preferably an inorganic solid electrolyte. This is because it has higher ion conductivity than organic polymer electrolytes. Also, this is because it has superior heat resistance compared to organic polymer electrolytes. Preferred inorganic solid electrolytes include, for example, lithium lanthanum zirconate, LiPON, Li 1+X AlXGe 2-XExamples of oxide solid electrolytes include (PO4)3, Li-SiO-based glass, and Li-Al-SO-based glass; and sulfide solid electrolytes such as Li2S-P2S5, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Si2S-P2S5, Li2S-P2S5-LiI-LiBr, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, and Li2S-P2S5-GeS2. In particular, sulfide solid electrolytes are preferred, sulfide solid electrolytes containing Li2S-P2S5 are more preferred, and sulfide solid electrolytes containing Li2S-P2S5-LiI-LiBr are even more preferred. Examples of binders that can be included in the negative electrode active material layer include butadiene rubber (BR), butylene rubber (IIR), acrylate butadiene rubber (ABR), and polyvinylidene fluoride (PVdF). Examples of conductive assistants that can be included in the negative electrode active material layer include carbon materials such as acetylene black and ketjen black, and metal materials such as nickel, aluminum, and stainless steel. The content of each component in the negative electrode active material layer may be the same as in the past. The shape of the negative electrode active material layer may also be the same as in the past. In particular, from the viewpoint of easily constructing the unit battery 100, a sheet-shaped negative electrode active material layer is preferable. In this case, the thickness of the negative electrode active material is preferably, for example, 0.1 μm or more and 1 mm or less, and more preferably 1 μm or more and 150 μm or less. However, it is preferable to determine the size (area and thickness) of the negative electrode active material layer so that the capacity of the negative electrode is larger than the capacity of the positive electrode.

[0020] (First solid electrolyte layer 31 and second solid electrolyte layer 32) In the unit battery 100, a first solid electrolyte layer 31 is laminated on one side surface of the first active material layer 21, and a second solid electrolyte layer 32 is laminated on the other side surface of the second active material layer 22. The first solid electrolyte layer 31 may be made of a plurality of layers. For example, a solid electrolyte layer may be laminated on the surface of one solid electrolyte layer, and the first solid electrolyte layer 31 may be made of a plurality of layers as a whole. The second solid electrolyte layer 32 may also be made of a plurality of layers. The first solid electrolyte layer 31 and the second solid electrolyte layer 32 may be layers containing the same type of material or layers containing different materials. They are preferably layers containing the same type of material.

[0021] The solid electrolyte layer is a layer containing at least an electrolyte. In addition to the solid electrolyte, the solid electrolyte layer can contain an arbitrary binder. The solid electrolyte is preferably the inorganic solid electrolyte described above, and more preferably a sulfide solid electrolyte. In this case, the sulfide solid electrolyte contained in the solid electrolyte layer is preferably a sulfide solid electrolyte containing Li2S-P2S5, and more preferably a sulfide solid electrolyte containing Li2S-P2S5-LiI-LiBr. The binder can be appropriately selected and used from the same binder as described above. The content of each component in the solid electrolyte layer may be the same as in the past. The shape of the solid electrolyte layer may also be the same as in the past. In particular, from the viewpoint of easily constructing the unit battery 100, a sheet-shaped solid electrolyte layer is preferable. In this case, the thickness of the solid electrolyte layer is preferably, for example, 0.1 μm to 1 mm, and more preferably 1 μm to 100 μm.

[0022] (Third active material layer 23 and fourth active material layer 24) In the unit battery 100, a third active material layer 23 is laminated on one side surface of the first solid electrolyte layer 31, and a fourth active material layer 24 is laminated on the other side surface of the second solid electrolyte layer 32. The third active material layer 23 may be composed of a plurality of layers. For example, an active material layer may be laminated on the surface of one active material layer to configure the third active material layer 23 as a whole of the plurality of layers. The fourth active material layer 24 may also be composed of a plurality of layers. When the first active material layer 21 and the second active material layer 22 are negative electrode active material layers, the third active material layer 23 and the fourth active material layer 24 are positive electrode active material layers. On the other hand, when the first active material layer 21 and the second active material layer 22 are positive electrode active material layers, the third active material layer 23 and the fourth active material layer 24 are negative electrode active material layers. In particular, the third active material layer 23 and the fourth active material layer 24 are preferably positive electrode active material layers. The third active material layer 23 and the fourth active material layer 24 may be layers containing the same type of material or layers containing different materials. They are preferably layers containing the same type of material. The positive electrode active material layer will be described below.

[0023] The positive electrode active material layer is a layer containing at least an active material. In addition to the active material, the positive electrode active material layer can optionally contain a solid electrolyte, a binder, a conductive assistant, and the like. The active material may be a known active material. Among known active materials, two materials having different potentials (charge / discharge potentials) at which a predetermined ion is absorbed and released can be selected, and the material showing a more noble potential can be used as the positive electrode active material, and the material showing a less noble potential can be used as the above-mentioned negative electrode active material. For example, when a lithium ion battery is constructed, lithium cobalt oxide, lithium nickel oxide, LiNi can be used as the positive electrode active material. 1 / 3 Co 1 / 3 Mn 1 / 3Various lithium-containing composite oxides such as lithium ion oxide, lithium manganate, and spinel-based lithium compounds can be used. The surface of the positive electrode active material may be coated with an oxide layer such as a lithium niobate layer, a lithium titanate layer, or a lithium phosphate layer. The solid electrolyte that can be contained in the positive electrode active material layer is preferably the inorganic solid electrolyte described above. In particular, a sulfide solid electrolyte is preferable, a sulfide solid electrolyte containing Li2S-P2S5 is more preferable, and a sulfide solid electrolyte containing Li2S-P2S5-LiI-LiBr is even more preferable. Examples of binders that can be contained in the positive electrode active material layer include butadiene rubber (BR), butylene rubber (IIR), acrylate butadiene rubber (ABR), and polyvinylidene fluoride (PVdF). Examples of conductive assistants that can be contained in the positive electrode active material layer include carbon materials such as acetylene black and ketjen black, and metal materials such as nickel, aluminum, and stainless steel. The content of each component in the positive electrode active material layer may be the same as that of the conventional one. The shape of the positive electrode active material layer may be the same as that of the conventional positive electrode active material layer. In particular, a sheet-shaped positive electrode active material layer is preferable from the viewpoint of easily constructing the unit battery 100. In this case, the thickness of the positive electrode active material layer is preferably, for example, 0.1 μm or more and 1 mm or less, and more preferably 1 μm or more and 150 μm or less.

[0024] (Second current collector layer 12 and third current collector layer 13) In the unit battery 100, the second current collector layer 12 is laminated on one side surface of the third active material layer 23, and the third current collector layer 13 is laminated on the other side surface of the fourth active material layer 24. The second current collector layer 12 may be made of a plurality of layers. For example, the second current collector layer 12 may be formed by overlapping a plurality of metal foils. The third current collector layer 13 may also be made of a plurality of layers. The second current collector layer 12 and the third current collector layer 13 may be layers containing the same type of material or layers containing different materials. Preferably, they are layers containing the same type of material. Furthermore, the first current collector layer 11 and the second current collector layer 12 may be layers containing the same type of material or layers containing different materials. Preferably, they are layers containing different materials. Furthermore, the first current collector layer 11 and the third current collector layer 13 may be layers containing the same type of material or layers containing different materials. Preferably, they are layers containing different materials.

[0025] The second current collector layer 12 and the third current collector layer 13 may be made of a metal foil or a metal mesh. In particular, a metal foil is preferred. Examples of metals constituting the second current collector layer 12 and the third current collector layer 13 include Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, stainless steel, and the like. In particular, Al is preferred. The second current collector layer 12 and the third current collector layer 13 may have some kind of coating layer (e.g., a carbon coating layer) on the surface thereof for adjusting the resistance. FIG. 2 shows the second current collector layer 12 and the third current collector layer 13 in which a carbon coating layer is disposed at a position in contact with the second active material layer 22 and the third active material layer 23, respectively. That is, in FIG. 2, the second current collector layer 12 has a second current collector foil 12a and a carbon coating layer 12b, and the third current collector layer 13 has a third current collector foil 13a and a carbon layer 13b.

[0026] The thickness of each of the second current collector layer 12 and the third current collector layer 13 is not particularly limited. For example, it is preferably 0.1 μm or more and 1 mm or less, and more preferably 1 μm or more and 100 μm or less. In the unit battery 100, when the first active material layer 21 and the second active material layer 22 are negative electrode active material layers, the second current collector layer 12 and the third current collector layer 13 function as positive electrode current collector layers. On the other hand, when the first active material layer 21 and the second active material layer 22 are positive electrode active material layers, the second current collector layer 12 and the third current collector layer 13 function as negative electrode current collector layers.

[0027] (Extending part 40) In the unit battery 100, at least the first current collector layer 11 extends outward beyond the third active material layer 23 and the fourth active material layer 24 to form the extension portion 40. In other words, when viewed in the stacking direction of the layers, the area of ​​the first current collector layer 11 is larger than each of the areas of the third active material layer 23 and the fourth active material layer 24. The extension portion 40 may include at least the first current collector layer 11. Preferably, at least the first current collector layer 11, the first active material layer 21, and the second active material layer 22 extend outward beyond the third active material layer 23 and the fourth active material layer 24 to form the extension portion 40. More preferably, as shown in Fig. 2, the first current collector layer 11, the first active material layer 21, the second active material layer 22, the first solid electrolyte layer 31, and the second solid electrolyte layer 32 extend outward beyond the third active material layer 23 and the fourth active material layer 24 to form an extension portion 40. The extension lengths of the first current collector layer 11, the first active material layer 21, the second active material layer 22, the first solid electrolyte layer 31, and the second solid electrolyte layer 32 may be the same or different. Preferably, the respective extension lengths are approximately the same as shown in Fig. 2.

[0028] <Protective layer 50> In the unit battery 100, the protective layer 50 is continuously provided over one side surface of the extension portion 40, the side surface of the extension portion 40, and the other side surface of the extension portion 40. As shown in FIG. 2, the protective layer 50 may have a substantially C-shaped cross section in the lamination direction. The protective layer 50 may be an insulating resin tape or an insulating resin. In terms of adhesion and processability, an insulating resin is preferable. Examples of the insulating resin include hot melt resin and ultraviolet curing resin. The ultraviolet curing resin is preferable. The type of ultraviolet curing resin is not particularly limited, and any general ultraviolet curing resin can be used. For example, cationic polymerization type and radical polymerization type ultraviolet curing resins can be used. In addition, the protective layer 50 may contain a filler from the viewpoint of improving the reliability of the thickness. The type of the filler is not particularly limited, and particles made of various materials can be used.

[0029] In the unit battery 100, the first current collector layer 11, the first active material layer 21, the second active material layer 22, the first solid electrolyte layer 31, and the second solid electrolyte layer 32 preferably extend outward beyond the third active material layer 23 and the fourth active material layer 24 to form the extension portion 40, and the protective layer 50 is preferably provided continuously over one side surface, the side surface, and the other side surface of the extension portion 40. This makes it possible to more reliably prevent the first current collector layer 11 and the first active material layer 21 from contacting the second current collector layer 12, and to more reliably prevent the first current collector layer 11 and the second active material layer 16 from contacting the third current collector layer 13. That is, short-circuiting of the positive electrode and the negative electrode can be further suppressed. In addition, the extension portion 40 can be further suppressed from sliding down.

[0030] The thickness of the protective layer 50 is not particularly limited. The thickness of the protective layer 50 may be appropriately determined in consideration of the balance between the volumetric energy density of the battery and the insulating function. For example, it is preferable that the thickness of the protective layer 50 on one side surface of the extension portion 40 is thinner than the thickness of the third active material layer 23, and it is preferable that the thickness of the protective layer 50 on the other side surface of the extension portion 40 is thinner than the thickness of the fourth active material layer 24. The thickness of the protective layer 50 on the side surface of the extension portion 40 may be thick. The protective layer 50 may be in contact with the side surface of the third active material layer 23 or the side surface of the fourth active material layer 24, or a gap may exist between the protective layer 50 and the side surface of the third active material layer 23 or the side surface of the fourth active material layer 24.

[0031] <Buffer material 60> In at least one unit battery 100, a buffer material 60 is disposed at least one of between an end 51 on the outer side in the width direction (the right side of the paper in FIG. 2 ) of one side surface of the protective layer 50 and the second current collector layer 12 and between an end 52 on the outer side in the width direction of the other side surface of the protective layer 50 and the third current collector layer 13. Preferably, in at least one unit battery 100, the buffer material 60 is disposed on the outer side in the stacking direction between the end 51 on the outer side in the width direction of one side surface of the protective layer 50 and the second current collector layer 12 and between the end 52 on the outer side in the width direction of the other side surface of the protective layer 50 and the third current collector layer 13. More preferably, in at least one unit battery 100, the buffer material 60 is disposed both between the end 51 on the outer side in the width direction of one side surface of the protective layer 50 and the second current collector layer 12 and between the end 52 on the outer side in the width direction of the other side surface of the protective layer 50 and the third current collector layer 13.

[0032] The embodiment in which "the buffer material 60 is disposed between the widthwise outer end 51 (end 52) of one side surface (other side surface) of the protective layer 50 and the second current collector layer 12 (third current collector layer 13)" includes, for example, an embodiment in which the buffer material 60 is disposed at the widthwise outer end 51 (end 52) of one side surface (other side surface) of the protective layer 50, and an embodiment in which the buffer material 60 is disposed at the other side surface (one side surface) of the second current collector layer 12 (third current collector layer 13) at a position overlapping with the widthwise outer end 51 (end 52) of the one side surface (other side surface) of the protective layer 50 as viewed in the stacking direction. The ends 51, 52 are, for example, within a range of 0.1 mm to 1 mm inward from the widthwise outer end of the one side surface (other side surface) of the protective layer 50.

[0033] FIG. 2 shows an embodiment in which a buffer material 60 is disposed at a position on the other side surface (one side surface) of the second current collector layer 12 (third current collector layer 13) that overlaps with an end 51 (end 52) on the width direction outer side of the one side surface (other side surface) of the protective layer 50 as viewed in the stacking direction. As shown in FIG. 2, the buffer material 60 is preferably disposed not only at a position overlapping with the end 51 (end 52) but also with a certain width. The thickness of the buffer material 60 may be such that it does not come into contact with the protective layer 50. The range of the buffer material 60 in the depth direction is not particularly limited as long as it is disposed within a range in which the current collector layer and the ends 51 and 52 of the protective layer 50 can come into contact with each other. The buffer material 60 may be disposed across the depth direction of the current collector layer.

[0034] 2, the second current collector layer 12 and the third current collector layer 13 have the carbon coating layers 12b and 13b disposed only in the areas that contact the third active material layer 23 and the fourth active material layer 24, respectively, and therefore the cushioning material 60 is disposed directly on the second current collector foil 12a and the third current collector foil 13a. However, the arrangement of the cushioning material 60 is not limited to this, and when the carbon coating layers 12b and 13c are disposed up to positions where they overlap the ends 51 and 52, the cushioning material 60 may be disposed on the surfaces of the carbon coating layers 12b and 13c.

[0035] Next, FIG. 3 shows a configuration in which cushioning materials 61, 62 are arranged at the outer end 51 (end 52) in the width direction of one surface (other surface) of the protective layer 50.

[0036] FIG. 3(a) shows a form in which a buffer material 61 is disposed at the end 51 (end 52) on the outer side in the width direction of one side surface (other side surface) of the protective layer 50. As shown in FIG. 3(a), the buffer material 61 is disposed so as to cover the ends 51, 52. The size of the buffer material 61 is not particularly limited as long as it is large enough to cover the ends 51, 52. As shown in FIG. 3(a), the buffer material 61 may be disposed from one side surface of the end of the protective layer 50 to at least a part of the side surface. The buffer material 61 is sized so as not to come into contact with the second current collector layer 12 (third current collector layer 13). The range of the buffer materials 61, 62 in the depth direction is not particularly limited as long as it is disposed within a range in which the current collector layer and the ends 51, 52 of the protective layer 50 can come into contact with each other. The buffer materials 61, 62 may be disposed throughout the depth direction of the protective layer 50.

[0037] 3(b) shows an embodiment in which the buffer material 62 is provided continuously over one surface, the side surface, and the other surface of the protective layer 50. The length of the one surface (other surface) of the buffer material 62 in the stacking direction is not particularly limited, as long as it is long enough not to contact the second current collector layer 12 (third current collector layer 13). The length of the side surface of the buffer material 62 in the width direction is not particularly limited, and may be set appropriately.

[0038] 2 and 3(a) and (b), the buffer materials 60, 61, and 62 are disposed at positions where the second or third current collector 12 or 13 and the end portion of the protective layer 50 can come into contact with each other. This makes it possible to suppress and alleviate stress concentration caused by contact between the second or third current collector 12 or 13 and the end portions 51 and 52 of the protective layer 50.

[0039] The buffer material is preferably made of a material softer than the protective layer 50. If the buffer material is made of a material harder than the protective layer 50, the current collector may be broken due to contact between the buffer material and the current collector. For example, the buffer material is preferably made of a resin having an elastic modulus in the range of 1 MPa to 500 MPa. Such a resin can be appropriately selected from hot melt resins, ultraviolet curable resins, etc.

[0040] FIG. 4 shows the arrangement of the cushioning material 60 in the all-solid-state battery 1000. As described above, the all-solid-state battery 1000 is formed by stacking a plurality of unit batteries 100. However, it is not necessary that the cushioning material 60 is arranged in all the unit batteries 100. That is, the cushioning material 60 may be arranged in at least one unit battery 100 among the plurality of unit batteries 100. For example, the cushioning material 60 may be arranged in at least one or both of the unit batteries 100 on the outside in the stacking direction of the all-solid-state battery 1000, may be arranged in the unit batteries 100 on the inside in the stacking direction, or may be arranged in all the unit batteries 100. In particular, from the viewpoint of suppressing contact between the ends of the second or third current collectors 12, 13 and the protective layer 50 due to external pressure or decompression treatment of the all-solid-state battery, it is preferable that the cushioning material 60 is arranged in at least one or both of the unit batteries 100 on the outside in the stacking direction of the all-solid-state battery 1000. FIG. 4 shows an example in which a cushioning material 60 is disposed on both unit batteries 100 that are disposed on the outer sides in the stacking direction of the all-solid-state battery 1000.

[0041] 5 and 6 show examples of arrangement of the cushioning material 60 in the all-solid-state battery 1000. Fig. 5 shows an example in which the cushioning material 60 is arranged only in the unit batteries 100 inside in the stacking direction of the all-solid-state battery 1000. Fig. 6 shows an example in which the cushioning material 60 is arranged in all the unit batteries 100 arranged in the all-solid-state battery 1000.

[0042] <Other configurations> A current collecting tab connected to each current collecting layer may be provided in the all-solid-state battery 1000. The all-solid-state battery 1000 may be housed in a laminate exterior body such as an Al laminate exterior body.

[0043] <Effects> In the all-solid-state battery 1000, by disposing a cushioning material at a predetermined position of the unit battery 100, it is possible to suppress and alleviate stress concentration caused by contact between the ends of the current collector and the protective layer 50 due to external pressure or decompression treatment during manufacturing. This makes it possible to suppress damage to the current collector. In addition, it is possible to suppress damage to the protective layer 50 and the extension portion 40 therein, and therefore to suppress short circuits caused by this. Therefore, the all-solid-state battery 1000 can improve structural reliability.

[0044] There may be cases where burrs or thorns are present on the protective layer 50. Even in such cases, by disposing a cushioning material at a predetermined position, it is possible to prevent the burrs or thorns from coming into contact with the current collector, and therefore to prevent the current collector from being broken by the burrs or thorns.

[0045] [Manufacturing method of all-solid-state battery 1000] The method for producing the all-solid-state battery 1000 is not particularly limited, but for example, it can be produced as follows.

[0046] First, a first active material layer 21 is laminated on one surface of the first current collector layer 11, a second active material layer 22 is laminated on the other surface of the first current collector layer 11, a first solid electrolyte layer 31 is laminated on one surface of the first active material layer 21, a second solid electrolyte layer 32 is laminated on the other surface of the second active material layer 22, a third active material layer 23 is laminated on one surface of the first solid electrolyte layer 31, and a fourth active material layer 24 is laminated on the other surface of the second solid electrolyte layer 32.

[0047] Here, the first active material layer 21 and the second active material layer 22 are either a negative electrode active material layer or a positive electrode active material layer, and when the first active material layer 21 and the second active material layer 22 are negative electrode active material layers, the third active material layer 23 and the fourth active material layer 24 are positive electrode active material layers, and when the first active material layer 21 and the second active material layer 22 are positive electrode active material layers, the third active material layer 23 and the fourth active material layer 24 are negative electrode active material layers. In addition, at least the first current collector layer 11 is extended outward in the width direction beyond the third active material layer 23 and the fourth active material layer 24 to form an extension portion 40.

[0048] The positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer can be prepared by a known method. For example, when preparing the positive electrode active material layer, the material constituting the positive electrode active material layer is dispersed in a predetermined organic solvent to form a slurry, and the slurry is applied to the surface of the current collector layer or the substrate, and then dried to obtain the positive electrode active material layer. The solid electrolyte layer and the negative electrode active material layer can also be prepared by a similar method. Then, the layers are stacked as described above, and pressed at a predetermined pressure to make the layers adhere to each other.

[0049] Next, the protective layer 50 is continuously disposed over one side surface, the side surface, and the other side surface of the extension portion 40. When a resin tape is used as the material of the protective layer 50, it is sufficient to simply attach the resin tape to the extension portion 40. When an insulating resin is used as the material of the protective layer 50, the insulating resin is disposed on the extension portion 40 and then cured to form the protective layer 50. A method for forming such a protective layer 50 is known. For example, JP 2020-004697 A can be referred to.

[0050] Next, the buffer material 60 is disposed. When the buffer material 60 is disposed on the protective layer 50, a resin material is disposed at a predetermined position on the protective layer 50, and then cured, so that the buffer material 60 can be disposed on the protective layer 50. When the buffer material 60 is disposed on the second current collector layer 12 and / or the third current collector layer 13, a resin material is disposed at a predetermined position on these current collector layers, and then cured, so that the buffer material 60 can be disposed on the second current collector layer 12 and / or the third current collector layer 13. As described above, it is sufficient that the buffer material 60 is disposed in at least one unit battery among the plurality of unit batteries 100.

[0051] Then, the second current collector layer 12 is laminated on one surface of the third active material layer 23, and the third current collector layer 13 is laminated on the other surface of the fourth active material layer 24, thereby obtaining a unit battery 100. Furthermore, by laminating the obtained unit batteries 100, an all-solid-state battery 1000 can be obtained. The obtained all-solid-state battery 1000 may be appropriately accommodated in a battery case such as an Al laminate exterior body. [Explanation of symbols]

[0052] 11 First current collector layer 12 Second current collector layer 13 Third current collector layer 21 First active material layer 22 Second active material layer 23 Third active material layer 24 Fourth active material layer 31 First solid electrolyte layer 32 Second solid electrolyte layer 40 Extension 50 protective layer 60 Cushioning material 100 unit batteries 1000 solid state battery

Claims

[Claim 1] A first current collector layer; a first active material layer laminated on one surface of the first current collector layer; a second active material layer laminated on the other surface of the first current collector layer; a first solid electrolyte layer laminated on one surface of the first active material layer; a second solid electrolyte layer laminated on the other surface of the second active material layer; a third active material layer laminated on one surface of the first solid electrolyte layer; a fourth active material layer laminated on the other surface of the second solid electrolyte layer; and a second current collector layer laminated on one surface of the third active material layer; a third current collector layer laminated on the other surface of the fourth active material layer; In an all-solid-state battery formed by stacking a plurality of unit cells comprising: the first active material layer and the second active material layer are either a negative electrode active material layer or a positive electrode active material layer, when the first active material layer and the second active material layer are negative electrode active material layers, the third active material layer and the fourth active material layer are positive electrode active material layers, and when the first active material layer and the second active material layer are positive electrode active material layers, the third active material layer and the fourth active material layer are negative electrode active material layers, In the unit battery, at least the first current collector layer extends outward beyond the third active material layer and the fourth active material layer to form an extension portion, a protective layer is continuously provided over one side surface of the extension portion, a side surface of the extension portion, and the other side surface of the extension portion; the thickness of the protective layer provided on one side surface of the extension portion is thinner than the thickness of the third active material layer; the thickness of the protective layer provided on the other side surface of the extension portion is thinner than the thickness of the fourth active material layer; in at least one of the unit batteries, a buffer material is disposed at least one between an outer end portion in the width direction of one surface of the protective layer and the second current collector layer and between an outer end portion in the width direction of the other surface of the protective layer and the third current collector layer, the buffer material is disposed on the other surface of the second current collector layer at a position overlapping an outer end in the width direction of the one surface of the protective layer as viewed in the stacking direction; and / or the buffer material is disposed on one surface of the third current collector layer at a position overlapping an outer end in the width direction of the other surface of the protective layer as viewed in the stacking direction, The thickness of the buffer material is such that the buffer material does not come into contact with the protective layer. All-solid-state battery.

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