Layered structure of all-solid-state battery, and method for manufacturing all-solid-state battery

Abstract

The present invention provides a layered structure of an all-solid-state battery having a plurality of layered structures in which a positive electrode layer and a frame that surrounds the periphery of the positive electrode layer are integrated, wherein the interface between the positive electrode layer and the frame of one of the plurality of layered structures and the interface between the positive electrode layer and the frame of another of the plurality of laminated structures, which is different from the one structure, are in different positions from one another as viewed from the layering direction of the structure.

Description

Layer structure of all-solid-state battery, manufacturing method of all-solid-state battery

[0001] The present invention relates to a laminate structure of an all-solid-state battery and a method for manufacturing an all-solid-state battery.

[0002] JP2021-77644A discloses a configuration in which, in an all-solid-state battery having a structure in which a solid electrolyte layer is sandwiched between a positive electrode layer and a negative electrode layer, a frame is arranged to surround the positive electrode layer, thereby protecting the side surface of the positive electrode layer and reducing short circuits between the positive electrode layer and the negative electrode layer.

[0003] However, in the case of the configuration of JP2021-77644A, the positive electrode layer expands and contracts during charging and discharging of the all-solid-state battery, creating a step in the thickness direction between the positive electrode layer and the frame, and this step may cause stress in the solid electrolyte layer, resulting in cracks.

[0004] Therefore, the present invention provides a stacked structure of an all-solid-state battery that suppresses the occurrence of cracks in the solid electrolyte layer, and a method for manufacturing the all-solid-state battery.

[0005] According to one aspect of the present invention, there is provided a stacked structure of an all-solid-state battery in which a plurality of structures, each of which is formed by integrating a positive electrode layer with a frame surrounding the periphery of the positive electrode layer, are stacked, and in this stacked structure, when viewed in the stacking direction of the structures, the position of the interface between the positive electrode layer and the frame of one of the plurality of stacked structures is different from the position of the interface between the positive electrode layer and the frame of another structure different from the one of the plurality of stacked structures.

[0006] FIG. 1 is a cross-sectional view (bottom) of an all-solid-state battery of this embodiment, and a plan view (top) showing a first edge and a second edge of a positive electrode layer constituting the all-solid-state battery. FIG. 2 is a partially enlarged view of FIG. 1. FIG. 3 is a cross-sectional view showing the initial state (before expansion / before contraction) of the all-solid-state battery of this embodiment. FIG. 4 is a cross-sectional view showing a state in which the positive electrode layer has contracted after the initial state shown in FIG. 3 in the all-solid-state battery of this embodiment. FIG. 5 is a cross-sectional view showing a state in which the positive electrode layer has expanded after the initial state shown in FIG. 3 in the all-solid-state battery of this embodiment. FIG. 6 is a cross-sectional view showing the initial state (before expansion / before contraction) of an all-solid-state battery of a comparative example. FIG. 7 is a cross-sectional view showing a state in which the positive electrode layer has contracted after the initial state shown in FIG. 6 in the all-solid-state battery of a comparative example. FIG. 8 is a cross-sectional view showing a state in which the positive electrode layer has expanded after the initial state shown in FIG. 6 in the all-solid-state battery of a comparative example. Fig. 9 is a diagram showing a manufacturing process (first stage) of the all-solid-state battery of this embodiment, in which Fig. 9(a) shows a state in which the material for the first cathode layer is applied to a cathode current collector foil, Fig. 9(b) shows a state in which the material for the frame is applied to the area surrounding the material for the cathode layer on the cathode current collector foil, and Fig. 9(c) shows a state in which the material for the second cathode layer is applied to the material for the first cathode layer and the material for the frame. Fig. 10 is a diagram showing a manufacturing process (second stage) of the all-solid-state battery of this embodiment, in which Fig. 10(d) shows a state in which the material for the second frame is applied to the area surrounding the material for the second cathode layer on the material for the first cathode layer and the material for the frame, and Fig. 10(e) shows the all-solid-state battery of this embodiment formed by pressing and drying. Fig. 11 is a diagram showing the manufacturing process of an all-solid-state battery of the comparative example, in which Fig. 11(a) shows a state in which the material for the first frame portion is applied to a positive electrode current collector foil in the shape of a rectangular frame, Fig. 11(b) shows a state in which the material for the first layer of the positive electrode layer is applied within the frame formed by the material for the first frame portion on the positive electrode current collector foil, and Fig. 11(c) shows an all-solid-state battery of the comparative example formed by pressing and drying. Fig. 12 is a cross-sectional view (lower diagram) of an all-solid-state battery of a modified example of this embodiment, and a plan view (upper diagram) of a first edge and a second edge of the positive electrode layer constituting the all-solid-state battery.

[0007] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0008] [Structure of All-Solid-State Battery] FIG. 1 is a cross-sectional view (lower diagram) of the all-solid-state battery of this embodiment, and a plan view (upper diagram) showing first edges 23A-23D and second edges 24A-24D of positive electrode layers 21A-21D that constitute the all-solid-state battery.

[0009] As shown in FIG. 1 (lower part), the all-solid-state battery of this embodiment has a structure in which, from the bottom, a positive electrode current collector foil 1, structures 2A-2D (positive electrode layers 21A-21D, frame portions 22A-22D), a solid electrolyte layer 3, a negative electrode layer 4, and a negative electrode current collector foil 5 are laminated, and these are packaged in a laminate exterior material (not shown).

[0010] The positive electrode current collector foil 1 is a thin plate made of a metal such as aluminum (Al). A positive electrode tab (not shown) is attached to the positive electrode current collector foil 1. The positive electrode tab (not shown) penetrates the laminate exterior material and is exposed to the outside, electrically connecting the positive electrode current collector foil 1 to the outside.

[0011] The structures 2A-2D include positive electrode layers 21A-21D and frame portions 22A-22D. The structures 2A-2D are stacked in four layers, but the number of layers can be set arbitrarily. The thicknesses of the structures 2A-2D are 20 μm-30 μm, respectively.

[0012] The positive electrode layers 21A-21D are layers containing a positive electrode active material containing, for example, sulfur, and release lithium ions during charging and absorb lithium ions during discharging. The positive electrode layers 21A-21D are formed by preparing a paste-like mixture of a positive electrode active material (NMC) mainly composed of nickel, manganese, and cobalt, a solid electrolyte, a conductive additive, and a binder in a predetermined blend ratio, applying the mixture, and then pressing and drying, or by applying and sintering the mixture (see FIGS. 9 and 10).

[0013] The side surfaces of the positive electrode layers 21A-21D are inclined in a direction facing the solid electrolyte layer 3. Therefore, the positive electrode layers 21A-21D have a tapered shape in which the width (cross-sectional area) decreases toward the solid electrolyte layer 3 and increases toward the positive current collector foil 1. The angle of inclination is approximately 60 to 75 degrees.

[0014] The frame portions 22A-22D are formed of a material other than a material that absorbs and releases lithium ions. The frame portions 22A-22D are arranged so as to surround the periphery of the positive electrode layers 21A-21D. When the positive electrode layers 21A-21D have a rectangular shape in a plan view, the frame portions 22A-22D have a rectangular frame shape.

[0015] The inner side surfaces of the frame portions 22A-22D are in contact with the inclined side surfaces of the positive electrode layers 21A-21D and are inclined in a direction facing the positive electrode current collector foil 1.

[0016] The frame portions 22A-22D are formed by applying a paste material for the frame portions 22A-22D, similar to the positive electrode layers 21A-21D, and then pressing and drying, or by applying and then sintering (see FIG. 9).

[0017] The solid electrolyte layer 3 is disposed on the uppermost structure 2D. The solid electrolyte layer 3 is a layer containing a solid electrolyte such as a sulfide solid electrolyte or an oxide solid electrolyte as a main component. The solid electrolyte layer 3 is formed by mixing the solid electrolyte and a binder at a predetermined blending ratio to form a paste-like mixture, applying the mixture to the uppermost structure 2D, and then pressing and drying, or applying and then sintering.

[0018] A layer of an anode active material containing at least lithium metal or a lithium alloy, or a thin plate of stainless steel, etc. can be used as the anode layer 4. The anode layer 4 absorbs lithium ions during charging and releases lithium ions during discharging.

[0019] The negative electrode current collector foil 5 is a thin plate made of a metal such as stainless steel (SUS) or copper (Cu). A negative electrode tab (not shown) is attached to the negative electrode current collector foil 5. The negative electrode tab (not shown) penetrates the laminate exterior material and is exposed to the outside, electrically connecting the negative electrode current collector foil 5 to the outside.

[0020] As shown in FIG. 1 (lower part), the side surface of the positive electrode layer 21A forms an interface between the positive electrode layer 21A and the frame portion 22A, the side surface of the positive electrode layer 21B forms an interface between the positive electrode layer 21B and the frame portion 22B, the side surface of the positive electrode layer 21C forms an interface between the positive electrode layer 21C and the frame portion 22C, and the side surface of the positive electrode layer 21D forms an interface between the positive electrode layer 21D and the frame portion 22D.

[0021] As shown in FIG. 1 (lower part), the side surface of the positive electrode layer 21A has a first edge 23A that forms the end on the solid electrolyte layer 3 side and a second edge 24A that forms the end on the positive electrode current collector foil 1 side.

[0022] Similarly, the side surface of positive electrode layer 21B has a first edge 23B that forms the end on the solid electrolyte layer 3 side and a second edge 24B that forms the end on the positive electrode current collector foil 1 side; the side surface of positive electrode layer 21C has a first edge 23C that forms the end on the solid electrolyte layer 3 side and a second edge 24C that forms the end on the positive electrode current collector foil 1 side; and the side surface of positive electrode layer 21D has a first edge 23D that forms the end on the solid electrolyte layer 3 side and a second edge 24D that forms the end on the positive electrode current collector foil 1 side.

[0023] As shown in FIG. 1 (top), each of the first edges 23A-23D (solid lines) and the second edges 24A-24D (dashed lines) has four rectangular edges.

[0024] In this embodiment, the first edges 23A-23D have the same shape, and the second edges 24A-24D also have the same shape. However, the first edges 23A-23D and the second edges 24A-24D are arranged so that their parallel components do not overlap each other when viewed from the stacking direction (the stacking direction of the structures 2A-2D, the solid electrolyte layer 3, etc.).

[0025] One edge constituting the first edge 23A is positioned at a different position from the edges constituting the first edge 23B, the first edge 23C, the first edge 23D, the second edge 24A, the second edge 24B, the second edge 24C, and the second edge 24D that are parallel to that edge in question, when viewed from the stacking direction, in the surface direction (the direction perpendicular to the stacking direction).

[0026] One edge constituting the first edge 23B is arranged at a different position in the surface direction when viewed from the stacking direction from the edges that are parallel to the one edge among the edges that respectively constitute the first edge 23A, the first edge 23C, the first edge 23D, the second edge 24A, the second edge 24B, the second edge 24C, and the second edge 24D.

[0027] One edge constituting the first edge 23C is arranged at a different position in the surface direction when viewed from the stacking direction from the edges that are parallel to the one edge among the edges that respectively constitute the first edge 23A, the first edge 23B, the first edge 23D, the second edge 24A, the second edge 24B, the second edge 24C, and the second edge 24D.

[0028] One edge constituting the first edge 23D is arranged at a different position in the surface direction when viewed from the stacking direction from the edges that are parallel to the one edge among the edges that respectively constitute the first edge 23A, the first edge 23B, the first edge 23C, the second edge 24A, the second edge 24B, the second edge 24C, and the second edge 24D.

[0029] One edge constituting the second edge 24A is arranged at a different position in the surface direction when viewed from the stacking direction from the edges that are parallel to the one edge among the edges that respectively constitute the first edge 23A, the first edge 23B, the first edge 23C, the first edge 23D, the second edge 24B, the second edge 24C, and the second edge 24D.

[0030] One edge constituting the second edge 24B is arranged at a different position in the surface direction when viewed from the stacking direction from the edges that are parallel to the one edge among the edges that respectively constitute the first edge 23A, the first edge 23B, the first edge 23C, the first edge 23D, the second edge 24A, the second edge 24C, and the second edge 24D.

[0031] One edge constituting the second edge 24C is arranged at a different position in the surface direction when viewed from the stacking direction from the edges that are parallel to the one edge among the edges that respectively constitute the first edge 23A, the first edge 23B, the first edge 23C, the first edge 23D, the second edge 24A, the second edge 24B, and the second edge 24D.

[0032] One edge constituting the second edge 24D is arranged at a different position in the surface direction when viewed from the stacking direction from the edges that are parallel to the one edge among the edges that respectively constitute the first edge 23A, the first edge 23B, the first edge 23C, the first edge 23D, the second edge 24A, the second edge 24B, and the second edge 24C.

[0033] The amount of misalignment in the plane direction of the position of the interface between positive electrode layer 21A and frame portion 22A of structure 2A, the position of the interface between positive electrode layer 21B and frame portion 22B of structure 2B, the position of the interface between positive electrode layer 21C and frame portion 22C of structure 2C, and the position of the interface between positive electrode layer 21D and frame portion 22AD of structure 2D is set appropriately so that first edges 23A-23D and second edges 24A-24D are arranged as described above, taking into consideration the thicknesses of each of structures 2A-2D and the inclination angles of the side surfaces of positive electrode layers 21A-21D.

[0034] As shown in FIG. 2, the second edge 24A is an intersection (edge) between the main surface of the positive electrode current collector foil 1 on the positive electrode layer 21A side and the interface between the side surface of the positive electrode layer 21A and the inner side surface of the frame portion 22A.

[0035] The first edge 23A is an intersection line (edge) of the interface between the side surface of the positive electrode layer 21A and the inner side surface of the frame portion 22A and the main surface of the positive electrode layer 21B on the positive electrode layer 21A side.

[0036] The second edge 24B is an intersection line (edge) between the main surface of the positive electrode layer 21B on the frame portion 22A side and the interface between the side surface of the positive electrode layer 21B and the inner side surface of the frame portion 22B.

[0037] The first edge 23B is an intersection line (edge) between the interface between the side surface of the positive electrode layer 21B and the inner side surface of the frame portion 22B and the main surface of the positive electrode layer 21B on the frame portion 22C side.

[0038] The second edge 24C is an intersection line (edge) between the main surface of the positive electrode layer 21C on the positive electrode layer 21B side and the interface between the side surface of the positive electrode layer 21C and the inner side surface of the frame portion 22C.

[0039] The first edge 23C is an intersection line (edge) of the interface between the side surface of the positive electrode layer 21C and the inner side surface of the frame portion 22C and the main surface of the positive electrode layer 21D on the positive electrode layer 21C side.

[0040] The second edge 24D is an intersection line (edge) between the main surface of the positive electrode layer 21D on the frame portion 22C side and the interface between the side surface of the positive electrode layer 21D and the inner side surface of the frame portion 22D.

[0041] The first edge 23D is an intersection line (edge) of the interface between the side surface of the positive electrode layer 21D and the inner side surface of the frame portion 22D and the main surface of the solid electrolyte layer 3 on the positive electrode layer 21D side.

[0042] In the manufacturing process of the all-solid-state battery of this embodiment, as will be described later (FIGS. 9 and 10), the material of the positive electrode layers 21A-21D (first materials 21Aa-21Da), the material of the frame portions 22A-22D (second materials 22Aa-22Da), and the material of the solid electrolyte layer 3 are applied onto the positive electrode current collector foil 1, and then the resulting mixture is pressed in the stacking direction and dried. This pressing causes stress to concentrate around the multiple intersection lines (edges).

[0043] Furthermore, in the manufacturing process of the all-solid-state battery of this embodiment, similarly to the above, the materials for the positive electrode layers 21A-21D (first materials 21Aa-21Da), the materials for the frame portions 22A-22D (second materials 22Aa-22Da), and the material for the solid electrolyte layer 3 can also be applied to the positive electrode current collector foil 1, and then sintered. However, due to the shrinkage of the materials caused by this sintering, stress is concentrated around the multiple intersecting lines (edges) (the areas surrounded by the dashed circles in the figure).

[0044] However, as shown in Figure 2, the multiple intersecting lines (eight in Figure 2) are arranged at different positions in the planar direction when viewed from the stacking direction, thereby dispersing stress that may occur during pressing in the planar direction. This reduces the concentration of stress on each of the positive electrode layers 21A-21D, the frame portions 22A-22D, and the solid electrolyte layer 3, and reduces cracks that may occur in the positive electrode layers 21A-21D, the frame portions 22A-22D, and the solid electrolyte layer 3 during manufacturing. Note that if stress concentration around the second edges 24A-24D is low and cracks around these edges are unlikely to occur, the second edges 24A-24D may be arranged at positions that overlap each other in the stacking direction, i.e., at the same position in the planar direction.

[0045] [State of all-solid-state battery of this embodiment during charge and discharge] Fig. 3 is a cross-sectional view showing the initial state (before expansion / contraction) of the all-solid-state battery of this embodiment. Fig. 4 is a cross-sectional view showing the state of the all-solid-state battery of this embodiment when the positive electrode layers 21A-21D have contracted after the initial state shown in Fig. 3. Fig. 5 is a cross-sectional view showing the state of the all-solid-state battery of this embodiment when the positive electrode layers 21A-21D have expanded after the initial state shown in Fig. 3.

[0046] As shown in FIG. 3, in the initial state (before expansion / contraction), the thicknesses of the positive electrode layers 21A-21D and the thicknesses of the frame portions 22A-22D are the same, and no step is generated between them.

[0047] As shown in FIG. 4 , when the positive electrode layers 21A-21D contract due to charging the all-solid-state battery, a first step is formed between the positive electrode layer 21A and the frame portion 22A in such a manner that the first edge 23A is lower than the upper surface of the frame portion 22A, a second step is formed between the positive electrode layer 21B and the frame portion 22B in such a manner that the first edge 23B is lower than the upper surface of the frame portion 22B, a third step is formed between the positive electrode layer 21B and the frame portion 22B in such a manner that the first edge 23C is lower than the upper surface of the frame portion 22C, and a fourth step is formed between the positive electrode layer 21D and the frame portion 22D in such a manner that the first edge 23D is lower than the upper surface of the frame portion 22D.

[0048] When the first to fourth steps are formed, the members above the steps are deformed, and the shapes of the steps are transferred to the members above.

[0049] The shape of the first step is transferred in this order to the lower surface of frame portion 22B, which is above frame portion 22B in the stacking direction, the upper surface of frame portion 22B, the lower surface of positive electrode layer 21C, the interface between frame portion 22C and positive electrode layer 21C, the upper surface of frame portion 22C, the lower surface of frame portion 22D, and the upper surface of frame portion 22D, and the shape of the first step transferred to the upper surface of frame portion 22D is transferred to the lower surface of solid electrolyte layer 3.

[0050] The shape of the second step is transferred in this order to the lower surface of positive electrode layer 21C, which is above it in the stacking direction, the upper surface of positive electrode layer 21C, the lower surface of positive electrode layer 21D, the interface between frame portion 22D and positive electrode layer 21D, and the upper surface of frame portion 22D, and the shape of the second step transferred to the upper surface of frame portion 22D is transferred to the lower surface of solid electrolyte layer 3.

[0051] The shape of the third step is transferred to the lower surface of frame portion 22D, which is above it in the stacking direction, and then to the upper surface of frame portion 22D, and the shape of the third step transferred to the upper surface of frame portion 22D is transferred to the lower surface of solid electrolyte layer 3.

[0052] The shape of the fourth step is directly transferred to the lower surface of the solid electrolyte layer 3 .

[0053] As shown in FIG. 4 , the first step, the second step, the third step, and the fourth step are arranged at different positions in the surface direction, and therefore the positions at which the first step, the second step, the third step, and the fourth step are transferred on the lower surface of the solid electrolyte layer 3 are different from one another in the surface direction.

[0054] Therefore, even when positive electrode layers 21A-21D shrink, the steps formed by structures 2A-2D are dispersed in the planar direction in a manner that forms stepped steps on the lower surface of solid electrolyte layer 3, and the shear stress on solid electrolyte layer 3 is dispersed, thereby making it possible to suppress the occurrence of cracks in solid electrolyte layer 3.

[0055] As shown in FIG. 5 , when the positive electrode layers 21A-21D expand due to discharging the all-solid-state battery, a fifth step is formed between the positive electrode layer 21A and the frame portion 22A in such a manner that the first edge 23A is higher than the upper surface of the frame portion 22A, a sixth step is formed between the positive electrode layer 21B and the frame portion 22B in such a manner that the first edge 23B is higher than the upper surface of the frame portion 22B, a seventh step is formed between the positive electrode layer 21B and the frame portion 22B in such a manner that the first edge 23C is higher than the upper surface of the frame portion 22C, and an eighth step is formed between the positive electrode layer 21D and the frame portion 22D in such a manner that the first edge 23D is higher than the upper surface of the frame portion 22D.

[0056] When the fifth to eighth steps are formed, the members above each step are deformed, and the shapes of each step are transferred to the members above.

[0057] The shape of the fifth step is transferred in this order to the lower surface of frame portion 22B, which is above frame portion 22B in the stacking direction, the upper surface of frame portion 22B, the lower surface of positive electrode layer 21C, the interface between frame portion 22C and positive electrode layer 21C, the upper surface of frame portion 22C, the lower surface of frame portion 22D, and the upper surface of frame portion 22D, and the shape of the fifth step transferred to the upper surface of frame portion 22D is transferred to the lower surface of solid electrolyte layer 3.

[0058] The shape of the sixth step is transferred in this order to the lower surface of positive electrode layer 21C, which is above it in the stacking direction, the upper surface of positive electrode layer 21C, the lower surface of positive electrode layer 21D, the interface between frame portion 22D and positive electrode layer 21D, and the upper surface of frame portion 22D, and the shape of the sixth step transferred to the upper surface of frame portion 22D is transferred to the lower surface of solid electrolyte layer 3.

[0059] The shape of the seventh step is transferred to the lower surface of frame portion 22D, which is above it in the stacking direction, and then to the upper surface of frame portion 22D, and the shape of the seventh step transferred to the upper surface of frame portion 22D is transferred to the lower surface of solid electrolyte layer 3.

[0060] The shape of the eighth step is directly transferred to the lower surface of the solid electrolyte layer 3 .

[0061] As shown in FIG. 5 , the fifth step, the sixth step, the seventh step, and the eighth step are arranged at different positions in the surface direction, and therefore the positions at which the fifth step, the sixth step, the seventh step, and the eighth step are transferred on the lower surface of the solid electrolyte layer 3 are different from one another in the surface direction.

[0062] Therefore, even when positive electrode layers 21A-21D expand, the plurality of steps formed by structures 2A-2D are dispersed in the planar direction in a manner that forms stepped steps on the lower surface of solid electrolyte layer 3, thereby dispersing the shear stress on solid electrolyte layer 3, thereby suppressing the occurrence of cracks in solid electrolyte layer 3.

[0063] [State of Comparative All-Solid-State Battery During Charge and Discharge] Fig. 6 is a cross-sectional view showing the initial state (before expansion / contraction) of the comparative all-solid-state battery. Fig. 7 is a cross-sectional view showing the state of the comparative all-solid-state battery when the positive electrode layers 21A-21D have contracted after the initial state shown in Fig. 6. Fig. 8 is a cross-sectional view showing the state of the comparative all-solid-state battery when the positive electrode layers 21A-21D have expanded after the initial state shown in Fig. 6.

[0064] 6, in the initial state (before expansion / contraction), the thicknesses of the positive electrode layers 21A-21D and the frame portions 22A-22D are the same, and no step is generated between them. However, the first edges 23A-23D are arranged in positions where they overlap each other when viewed from the stacking direction, and the second edges 24A-24D are also arranged in positions where they differ from each other when viewed from the stacking direction.

[0065] 7, when the all-solid-state battery is charged, the positive electrode layers 21A-21D contract, and the first to fourth steps are formed in the same manner as described above. However, the first to fourth steps are arranged in positions that overlap each other when viewed from the stacking direction, and a step having a shape that is a combination of the shapes of the first to fourth steps is transferred to the lower surface of the solid electrolyte layer 3.

[0066] 8, when the all-solid-state battery is discharged, the positive electrode layers 21A-21D expand, and the fifth to eighth steps are formed in the same manner as described above. However, the fifth to eighth steps are arranged in positions that overlap each other when viewed from the stacking direction, and a step having a shape that is a combination of the shapes of the fifth to eighth steps is transferred to the lower surface of the solid electrolyte layer 3.

[0067] Therefore, the steps formed in structures 2A-2D due to the contraction or expansion of positive electrode layers 21A-21D are transferred to one location on the lower surface of solid electrolyte layer 3 without being dispersed in the planar direction, and the shear stress on solid electrolyte layer 3 cannot be dispersed, making it difficult to suppress the occurrence of cracks.

[0068] [Manufacturing Process of All-Solid-State Battery of This Embodiment] FIG. 9 is a diagram showing a manufacturing process (first stage) of the all-solid-state battery of this embodiment, in which FIG. 9( a) shows a state in which the material of the first layer of positive electrode layer 21A (first material 21Aa) is applied to the positive electrode current collector foil 1, FIG. 9( b) shows a state in which the material of frame portion 22A (second material 22Aa) is applied to the area surrounding the material of positive electrode layer 21A on the positive electrode current collector foil 1, and FIG. 9( c) shows a state in which the material of the second layer of positive electrode layer 21B (first material 21Ba) is applied to the material of the first layer of positive electrode layer 21A (first material 21Aa) and the material of frame portion 22A (second material 22Aa). 10(d) shows the state in which the material (second material 22Ba) for the second layer frame portion 22B has been applied to the area surrounding the material (first material 21Ba) for the second layer cathode layer 21B on the material (first material 21Aa) for the first layer cathode layer 21A and the material (second material 22Aa) for the frame portion 22A, and FIG. 10(e) shows the all-solid-state battery of this embodiment formed by pressing and drying. In the all-solid-state battery of this embodiment, the cathode layers 21A-21D, frame portions 22A-22D, and solid electrolyte layer 3 are formed by coating.

[0069] 9(a), a first material 21Aa, which will be the material for the positive electrode layer 21A, is applied to the positive electrode current collector foil 1. Before drying, the first material 21Aa is in a semi-solid state, and as shown in FIG.

[0070] 9(b), a second material 22Aa, which will be the material for the frame portion 22A, is applied so as to surround the periphery of the first material 21Aa on the positive current collector foil 1. The inner side surface of the second material 22Aa is in contact with the side surface of the first material 21Aa and is formed into a shape that follows the side surface, and is inclined in a direction facing the positive current collector foil 1. The outer side surface of the second material 22Aa is inclined so as to face upward.

[0071] 9( c), a first material 21Ba, which will be the material for the second layer of positive electrode layer 21B, is applied onto the first material 21Aa and second material 22Aa of the first layer. At this time, the first material 21Ba is applied so that a first edge 23B of the first material 21Ba is positioned at a different position in the surface direction from the first edge 23A and second edge 24A of the first material 21Aa when viewed from the stacking direction, and so that a second edge 24B of the first material 21Ba is positioned at a different position in the surface direction from the first edge 23A and second edge 24A of the first material 21Aa when viewed from the stacking direction.

[0072] As shown in Figure 10 (d), a second material 22Ba, which will be the material for the frame portion 22B of the second layer, is applied to the area on top of the first material 21Aa and second material 22Aa of the first layer and surrounding the first material 21Ba of the second layer.

[0073] Thereafter, although not shown (see FIG. 1 , etc.), a first material 21Ca, which will be the material for the third layer of positive electrode layer 21C, is applied onto the first material 21Ba and second material 22Ba for the second layer. At this time, first material 21Ca is applied so that a first edge 23C of first material 21Ca is positioned at a different position in the surface direction from the first edge 23A and second edge 24A of first material 21Aa and the first edge 23B and second edge 24B of first material 21Ba when viewed from the stacking direction, and so that a second edge 24C of first material 21Ca is positioned at a different position in the surface direction from the first edge 23A and second edge 24A of first material 21Aa and the first edge 23B and second edge 24B of first material 21Ba when viewed from the stacking direction.

[0074] A second material 22Ca, which will be the material for the frame portion 22C of the third layer, is applied to an area on the first material 21Ba and second material 22Ba of the second layer and surrounding the first material 21Ca of the third layer.

[0075] A first material 21Da, which will be the material for the positive electrode layer 21D in the fourth layer, is applied onto the first material 21Ca and the second material 22Ca in the third layer. In this case, the first material 21Da is applied so that the first edge 23D of the first material 21Da is positioned differently in the surface direction from the first edge 23A and second edge 24A of the first material 21Aa, the first edge 23B and second edge 24B of the first material 21Ba, and the first edge 23C and second edge 24C of the first material 21Ca when viewed from the stacking direction, and so that the second edge 24D of the first material 21Da is positioned differently in the surface direction from the first edge 23A and second edge 24A of the first material 21Aa, the first edge 23B and second edge 24B of the first material 21Ba, and the first edge 23C and second edge 24C of the first material 21Ca when viewed from the stacking direction.

[0076] A second material 22Da, which will be the material for the frame portion 22D of the fourth layer, is applied to the area surrounding the first material 21Da of the fourth layer on the first material 21Ca and second material 22Ca of the third layer.

[0077] The material for the solid electrolyte layer 3 is applied onto the first material 21Da and second material 22Da in the fourth layer, and then the negative electrode layer 4 and negative electrode current collector foil 5 are laminated on top of that in this order. The laminate is then pressed in the lamination direction and dried, or the entire structure is sintered. As a result, as shown in FIG. 10( e), the first materials 21Aa-21Da become the positive electrode layers 21A-21D, the second materials 22Aa-22Da become the frame portions 22A-22D, and the material for the solid electrolyte layer 3 becomes the solid electrolyte layer 3, thereby forming the all-solid-state battery of this embodiment.

[0078] [Manufacturing Process of All-Solid-State Battery of Comparative Example] FIG. 11 is a diagram showing the manufacturing process of the all-solid-state battery of the comparative example, in which FIG. 11( a) shows a state in which the material of the first-stage frame portion 22A (second material 22Aa) is applied to the positive electrode current collector foil 1 in the shape of a rectangular frame, FIG. 11( b) shows a state in which the material of the first-stage positive electrode layer 21A (first material 21Aa) is applied within the frame formed by the material of the first-stage frame portion 22A (second material 22Aa) on the positive electrode current collector foil 1, and FIG. 11( c) shows the all-solid-state battery of the comparative example formed by pressing and drying.

[0079] 11( a), a second material 22Aa that will be the material for the frame portion 22A is applied in a rectangular frame shape onto the positive electrode current collector foil 1. At this time, both the inner side surface and the outer side surface of the second material 22Aa are inclined so as to face upward.

[0080] 11B, the first material 21Aa, which will be the material for the positive electrode layer 21A, is applied so as to fill the rectangular recess formed by the second material 22Aa. At this time, the side surface of the first material 21Aa contacts the inner side surface of the second material 22Aa and is formed to follow the shape of the inner side surface. The side surface of the first material 21Aa is inclined in a direction facing the positive electrode current collector foil 1.

[0081] Thereafter, the first materials 21Ba-21Da and the second materials 22Ba-22Da are applied in the same manner as in the all-solid-state battery of this embodiment ( FIGS. 9 and 10 ), but in the order of second material 22Ba, first material 21Ba, second material 22Ca, first material 21Ca, second material 22Da, and first material 21Da. Then, on top of the fourth layer of first material 21Da and second material 22Da, the material for solid electrolyte layer 3 is applied, and then the negative electrode layer 4 and negative electrode current collector foil 5 are stacked in this order. The resultant structure is then pressed in the stacking direction and dried, or the entire structure is sintered, thereby forming the all-solid-state battery of the comparative example shown in FIG. 11( c).

[0082] 11C, in the all-solid-state battery of the comparative example, the first material 21Da is applied after the second material 22Da is applied, so that the upper surface of the first material 21Da may be higher than the upper surface of the second material 22Da. In this case, the first material 21Da that comes into contact with the material of the solid electrolyte layer 3 during pressing may leak out and cover the second material 22Da.

[0083] In this case, the leaked portion of the positive electrode layer 21D formed by pressing, drying, etc. can also become a path for the flow of lithium ions, which may cause the charge / discharge reaction to become uneven in the surface direction, resulting in a decrease in the charge and discharge amounts.

[0084] On the other hand, in the all-solid-state battery of this embodiment (see FIG. 10 ), the first material 21Da is applied first, and then the second material 22Da is applied, which prevents the upper surface of the first material 21Da from being higher than the upper surface of the second material 22Da and prevents the material of the positive electrode layer 21D, which comes into contact with the material of the solid electrolyte layer 3 during pressing, from covering the material of the fourth-stage frame portion 22D. Therefore, the all-solid-state battery of this embodiment can have more stable charge and discharge performance than the all-solid-state battery of the comparative example.

[0085] [All-Solid-State Battery According to a Modification of the Present Embodiment] FIG. 12 is a cross-sectional view (lower diagram) of an all-solid-state battery according to a modification of the present embodiment, and a plan view (upper diagram) of first edges 23A-23D and second edges 24A-24D of positive electrode layers 21A-21D constituting the all-solid-state battery.

[0086] As shown in FIG. 12 (lower diagram), the all-solid-state battery of the modified example has a configuration similar to that of the all-solid-state battery shown in FIG. 1 etc., but as shown in FIG. 12 (upper diagram), positive electrode layers 21A-21D and frame portions 22A-22D are concentrically arranged when viewed from the stacking direction.

[0087] As shown in FIG. 12 (lower diagram), the positive electrode layers 21A-21D are arranged so that the widths thereof are as follows: positive electrode layer 21A<positive electrode layer 21B<positive electrode layer 21C<positive electrode layer 21D.

[0088] As shown in FIG. 12 (top diagram), from the inside, the first edge 23A of the positive electrode layer 21A, the first edge 23B of the positive electrode layer 21B, the second edge 24A of the positive electrode layer 21A, the second edge 24B of the positive electrode layer 21B, the first edge 23C of the positive electrode layer 21C, the first edge 23D of the positive electrode layer 21D, the second edge 24C of the positive electrode layer 21C, and the second edge 24D of the positive electrode layer 21D are arranged in this order, and the edges are arranged at different positions in the planar direction without overlapping with each other in the stacking direction.

[0089] As a result, when the modified all-solid-state battery is pressed to form, the stress concentrations that occur around the first edges 23A-23D and around the second edges 24A-24D are dispersed in the planar direction without overlapping with each other as viewed from the stacking direction, thereby reducing the occurrence of cracks in the positive electrode layers 21A-21D, the frame portions 22A-22D, and the solid electrolyte layer 3 during the manufacture of the modified all-solid-state battery.

[0090] Furthermore, since first edges 23A-23D are dispersed in the planar direction without overlapping with each other when viewed from the stacking direction around the entire periphery, the occurrence of cracks in solid electrolyte layer 3 during charge and discharge of the all-solid-state battery of the modified example can be efficiently reduced.

[0091] [Effects of the Present Embodiment] The stacked structure of the all-solid-state battery of the present embodiment includes a plurality of stacked structures 2A-2D, each of which is formed by integrating positive electrode layers 21A-21D and frame portions 22A-22D surrounding the peripheries of the positive electrode layers 21A-21D. When viewed from the stacking direction of the structures 2A-2D, the position of the interface (first edge 23A, second edge 24A) between the positive electrode layer 21A and the frame portion 22A of one (for example) structure 2A of the plurality of stacked structures 2A-2D is different from the position of the interface (first edge 23B-23D, second edge 24B-24D) between the positive electrode layer 21B-21D and the frame portion 22B-22D of another (for example) structure 2B-2D that is different from the one (for example) structure 2A of the plurality of stacked structures 2A-2D.

[0092] With the above configuration, the positive electrode layers 21A-21D contract when the all-solid-state battery is charged, and the positive electrode layers 21A-21D expand when the all-solid-state battery is discharged. This causes multiple steps to be formed between the positive electrode layers 21A-21D and the frame portions 22A-22D, and these multiple steps are transferred to the solid electrolyte layer 3. However, in the structures 2A-2D, the positions of the interfaces between the positive electrode layers 21A-21D and the frame portions 22A-22D differ in the planar direction between one (for example) structure 2A and another (for example) structure 2B-2C that is different from the one (for example) structure 2A, and therefore the positions at which the multiple steps are formed also differ in the planar direction. Therefore, even when the positive electrode layers 21A-21D contract and expand, the multiple steps formed in the structures 2A-2D are dispersed in the planar direction in a manner that forms step-like steps on the lower surface of the solid electrolyte layer 3, thereby dispersing the shear stress on the solid electrolyte layer 3, thereby suppressing the occurrence of cracks in the solid electrolyte layer 3.

[0093] In this embodiment, the side surfaces (first edges 23A-23D, second edges 24A-24D) that form the interfaces (first edges 23A-23D, second edges 24A-24D) of the positive electrode layers 21A-21D are inclined with respect to the stacking direction.

[0094] During pressing, stress is concentrated in the areas surrounding the first edges 23A-23D and the second edges 24A-24D, which are the ends in the stacking direction of the interfaces of the positive electrode layers 21A-21D. Therefore, stress is concentrated in specific portions of positive electrode layer 21A and frame portion 22A sandwiched between the region surrounding first edge 23A and the region surrounding second edge 24A, specific portions of positive electrode layer 21B and frame portion 22B sandwiched between the region surrounding first edge 23B and the region surrounding second edge 24B, specific portions of positive electrode layer 21C and frame portion 22C sandwiched between the region surrounding first edge 23C and the region surrounding second edge 24C, specific portions of positive electrode layer 21D and frame portion 22D sandwiched between the region surrounding first edge 23D and the region surrounding second edge 24D, and solid electrolyte layer 3, which may cause cracks to occur in positive electrode layers 21A-21D, frame portions 22A-22D, and solid electrolyte layer 3 during pressing. However, with the above-described configuration, the side surfaces are inclined, so that first edge 23A and second edge 24A are at different positions in the surface direction, first edge 23B and second edge 24B are at different positions in the surface direction, first edge 23C and second edge 24C are at different positions in the surface direction, and first edge 23D and second edge 24D are at different positions in the surface direction, thereby dispersing the locations where stress concentrates in the surface direction. Therefore, it is possible to reduce the occurrence of cracks in positive electrode layers 21A-21D, frame portions 22A-22D, and solid electrolyte layer 3 due to the concentration of stress during pressing.

[0095] In this embodiment, of the multiple stacked structures 2A-2D, a solid electrolyte layer 3 is stacked on structure 2D, which is one of a pair of ends in the stacking direction, and the side surface (of positive electrode layers 21A-21D) is inclined in a direction facing the solid electrolyte layer 3.

[0096] With the above configuration, when the structures 2A-2D are formed by coating, for example, the material of the positive electrode layer 21D (first material 21Da) is applied first, and then the material of the frame portion 22D (second material 22Da) is applied. Therefore, the upper surface of the material of the positive electrode layer 21D (first material 21Da) is higher than the upper surface of the material of the frame portion 22D (second material 22Da), and leakage of the material of the positive electrode layer 21D (first material 21Da) onto the upper surface of the material of the frame portion 22D (second material 22Da) during pressing can be reduced. This stabilizes the charge / discharge performance of the all-solid-state battery.

[0097] In this embodiment, the side surfaces of the positive electrode layers 21A-21D include first edges 23A-23D that form one of a pair of ends in the stacking direction of the positive electrode layers 21A-21D and are arranged on the solid electrolyte layer 3 side, and second edges 24A-24D that form the other of the pair of ends in the stacking direction of the positive electrode layers 21A-21D. When viewed from the stacking direction, the first edge 23A of one (for example) structure 2A of the multiple stacked structures 2A-2D is located on the solid electrolyte layer 3 side. (For example) structure 2A is positioned at a position spaced apart from where it overlaps with the first edge 23B-23D of another (for example) structure 2B-2C different from structure 2A and where it overlaps with the second edge 24B-24D of the other (for example) structure 2B-2C, and further, the second edge 24A of one (for example) structure 2A is positioned at a position spaced apart from where it overlaps with the first edge 23B-23D of the other (for example) structure 2B-2D and where it overlaps with the second edge 24B-24D of the other (for example) structure 2B-2D.

[0098] As described above, stress is concentrated during pressing in the regions surrounding the first edges 23A-23D and second edges 24A-24D, which are the ends of the interfaces of the positive electrode layers 21A-21D in the stacking direction. However, the multiple (eight in this embodiment) regions where stress is concentrated are positioned at different positions in the planar direction (direction perpendicular to the stacking direction) when viewed from the stacking direction, thereby dispersing stress that may occur during pressing in the planar direction (direction perpendicular to the stacking direction). This reduces stress concentration in each of the positive electrode layers 21A-21D, frame portions 22A-22D, and solid electrolyte layer 3, and reduces cracks that may occur in the positive electrode layers 21A-21D, frame portions 22A-22D, and solid electrolyte layer 3 during manufacturing.

[0099] The method for manufacturing an all-solid-state battery of this embodiment is a method for manufacturing an all-solid-state battery in which a plurality of structures 2A-2D, each of which is formed by integrating positive electrode layers 21A-21D and frame portions 22A-22D surrounding the positive electrode layers 21A-21D, are stacked, and the method comprises the steps of: forming structure 2A by applying (for example) a first material 21Aa that will be the material of positive electrode layer 21A and (for example) a second material 22Aa that will be the material of frame portion 22A in an arrangement of positive electrode layer 21A and frame portion 22A; and then applying (for example) a new first material 21Ba and a new second material 22Ba on structure 2A in an arrangement of positive electrode layer 21B and frame portion 22B to form new structure 2B on structure 2A. and then a new structure is placed on top of the structure. This process is repeated to stack a plurality of structures 2A-2D, and first materials 21Aa-21Da and second materials 22Aa-22D are applied so that, when viewed from the stacking direction of structures 2A-2D, the position of the interface (first edge 23A, second edge 24A) between positive electrode layer 21A and frame portion 22A of one (for example) structure 2A of the plurality of stacked structures 2A-2D is different from the position of the interface (first edge 23B-23D, second edge 24B-24D) between positive electrode layer 21B-21D and frame portion 22B-22D of another structure 2B-2D that is different from one structure 2A of the plurality of stacked structures 2A-2D.

[0100] According to the above method, the positive electrode layers 21A-21D contract when the all-solid-state battery is charged, and the positive electrode layers 21A-21D expand when the all-solid-state battery is discharged. This causes multiple steps to be formed between the positive electrode layers 21A-21D and the frame portions 22A-22D, and these multiple steps are transferred to the solid electrolyte layer 3. However, in the structures 2A-2D, the positions of the interfaces between the positive electrode layers 21A-21D and the frame portions 22A-22D differ in the planar direction between one (for example) structure 2A and another (for example) structure 2B-2C that is different from the one (for example) structure 2A, and therefore the positions at which the multiple steps are formed also differ in the planar direction. Therefore, even when the positive electrode layers 21A-21D contract and expand, the multiple steps formed in the structures 2A-2D are dispersed in the planar direction in a manner that forms step-like steps on the lower surface of the solid electrolyte layer 3, thereby dispersing the shear stress on the solid electrolyte layer 3, thereby suppressing the occurrence of cracks in the solid electrolyte layer 3.

[0101] In this embodiment, when forming structures 2A-2D, first material 21Aa-21Da is applied and then second material 22Aa-22Da is applied. More specifically, when forming structure 2A, first material 21Aa is applied and then second material 22Aa is applied, when forming structure 2B, first material 21Ba is applied and then second material 22Ba is applied, when forming structure 2C, first material 21Ca is applied and then second material 22Ca is applied, and when forming structure 2D, first material 21Da is applied and then second material 22Da is applied.

[0102] According to the above method, for example, the material of the positive electrode layer 21D (first material 21Da) is applied first, and then the material of the frame portion 22D (second material 22Da) is applied. Therefore, the upper surface of the material of the positive electrode layer 21D (first material 21Da) is higher than the upper surface of the material of the frame portion 22D (second material 22Da). This reduces leakage of the material of the positive electrode layer 21D (first material 21Da) onto the upper surface of the material of the frame portion 22D (second material 22Da) during pressing. This stabilizes the charge / discharge performance of the all-solid-state battery.

[0103] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

Claims

1. A stacked structure of an all-solid-state battery in which a plurality of structures each having a positive electrode layer and a frame surrounding the periphery of the positive electrode layer integrated together are stacked, wherein, when viewed from the stacking direction of the structures, the position of the interface between the positive electrode layer and the frame of one of the plurality of stacked structures is different from the position of the interface between the positive electrode layer and the frame of another of the plurality of stacked structures that is different from the one of the plurality of stacked structures.

2. The stacked structure of an all-solid-state battery according to claim 1, wherein the side surface forming the interface of the positive electrode layer is inclined with respect to the stacking direction.

3. The stacked structure of an all-solid-state battery according to claim 2, wherein a solid electrolyte layer is stacked on one of a pair of end portions in the stacking direction among the plurality of stacked structures, and the side surface is inclined in a direction facing the solid electrolyte layer.

4. The stacked structure of an all-solid-state battery according to claim 3, wherein the side surface includes a first edge that forms one of a pair of ends of the positive electrode layer in the stacking direction and that is located on the solid electrolyte layer side, and a second edge that forms the other of the pair of ends of the positive electrode layer in the stacking direction, and when viewed from the stacking direction, the first edge of one of the plurality of stacked structures is located at a position that is separated from a position where it overlaps with the first edge of another structure different from the one of the plurality of stacked structures and a position where it overlaps with the second edge of the other structure, and further the second edge of the one structure is located at a position that is separated from a position where it overlaps with the first edge of the other structure and a position where it overlaps with the second edge of the other structure.

5. A method for manufacturing an all-solid-state battery in which a plurality of structures each having a positive electrode layer and a frame surrounding the positive electrode layer are stacked together, the method comprising: forming the structure by applying a first material that is to be the material of the positive electrode layer and a second material that is to be the material of the frame in a manner that results in the arrangement of the positive electrode layer and the frame; then applying a new first material and a new second material onto the structure in a manner that results in the arrangement of the positive electrode layer and the frame, thereby arranging the new structure on the structure; and repeating this process to stack a plurality of the structures; and applying the first material and the second material so that, when viewed in the stacking direction of the structures, the position of the interface between the positive electrode layer and the frame of one of the plurality of stacked structures is different from the position of the interface between the positive electrode layer and the frame of another of the plurality of stacked structures that is different from the one structure.

6. The method for manufacturing an all-solid-state battery according to claim 5, wherein the first material is applied before the second material is applied when forming the structure.

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