Solid battery and method for manufacturing solid battery

Abstract

To provide a solid-state battery, capable of reducing a lamination space factor of a solid electrolyte as well as reducing resistivity.SOLUTION: A solid-state battery contains a lamination body formed by alternately laminating a positive electrode plate and a negative electrode plate, and a solid electrolyte layer is formed in a lamination surface of any one of the positive electrode plate and the negative electrode plate. In at least one of the positive electrode plate and the negative electrode plate, the solid electrolyte layer is formed in at least one part of an end surface. An area of the lamination surface of one electrode plate of the positive electrode plate and the negative electrode plate is larger than that of the lamination surface of the other electrode plate of the positive electrode plate and the negative electrode plate, and an external edge of the one electrode plate is arranged on the side outer than the external edge of the other electrode plate. In the one electrode plate, it is preferable that the solid electrolyte layer be formed in at least one of the end surface.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a solid battery and a method for manufacturing the same.

Background Art

[0002] Conventionally, as a secondary battery having a high energy density, lithium-ion secondary batteries have been widely popularized. A lithium-ion secondary battery has a structure in which a separator is present between a positive electrode and a negative electrode and is filled with a liquid electrolyte.

[0003] Since the electrolytic solution of a lithium-ion secondary battery is usually a flammable organic solvent, there has been a problem in particular with respect to safety against heat. Therefore, solid batteries using an inorganic solid electrolyte instead of an organic liquid electrolyte have been proposed. For example, techniques related to solid batteries including a laminate having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer have been proposed (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the solid battery described in Patent Document 1, a sheet-like solid electrolyte layer formed by pressure molding is disposed between each electrode layer. Since the sheet-like solid electrolyte layer requires strength, a thickness of about several tens of μm is required. For this reason, there has been room for improvement in terms of the increase in the stacking occupation ratio of the solid electrolyte and the increase in the resistivity due to the increase in the distance between the electrodes.

[0006] The present invention has been made in view of the above, and an object thereof is to provide a solid battery capable of reducing the stacking occupation ratio of a solid electrolyte and reducing the resistivity.

Means for Solving the Problems

[0007] (1) The present invention relates to a solid battery including a laminate formed by alternately laminating a positive electrode plate and a negative electrode plate, wherein a solid electrolyte layer is formed on at least one of the lamination surfaces of the positive electrode plate and the negative electrode plate.

[0008] According to the invention of (1), it is possible to provide a solid battery capable of reducing the occupation ratio of the solid electrolyte in the lamination and reducing the resistivity.

[0009] (2) The solid battery according to (1), wherein a solid electrolyte layer is formed on at least a part of the end face of at least one of the positive electrode plate and the negative electrode plate.

[0010] According to the invention of (2), insulation can be ensured between at least one of the end faces of the positive electrode plate and the negative electrode plate and the end face of the other electrode plate.

[0011] (3) The solid battery according to (1) or (2), wherein the area of the lamination surface of one of the positive electrode plate and the negative electrode plate is larger than the area of the lamination surface of the other of the positive electrode plate and the negative electrode plate, and the outer edge of the one electrode plate is disposed outside the outer edge of the other electrode plate, and a solid electrolyte layer is formed on at least a part of the end face of the one electrode plate.

[0012] According to the invention of (3), insulation between the electrode plates can be ensured even when a thin solid electrolyte layer is formed on the electrode plate instead of the sheet-like solid electrolyte layer.

[0013] (4) The solid battery according to (3), wherein a recess wider than the width of the electrode tab is provided at a position on the end face of the one electrode plate corresponding to the electrode tab extending from the other electrode plate, a solid electrolyte layer is formed in the recess, and a solid electrolyte layer is formed on the lamination surface of the one electrode plate.

[0014] According to the invention of (4), insulation can be ensured between the end face of one electrode plate and the electrode tab extending from the other electrode plate, and a laminate can be formed without forming a solid electrolyte layer on the other electrode plate, so that the manufacturing process of the solid battery can be simplified.

[0015] (5) A solid electrolyte layer is formed on the laminated surface of the positive electrode plate and the negative electrode plate, and a concave portion is provided at a position corresponding to the end portion of the electrode tab extending from the other electrode plate on the end face of the one electrode plate, and a solid electrolyte layer is formed in the concave portion. The solid battery according to (3).

[0016] According to the invention of (5), a laminate can be formed that can ensure insulation between the end face of one electrode plate and the electrode tab extending from the other electrode plate.

[0017] (6) Further, the present invention is a method for manufacturing a solid battery including a manufacturing process of an electrode for a solid battery, and the manufacturing process of the electrode for a solid battery includes an electrode material coating step of coating an electrode material on a current collector, and a drilling step of forming a hole portion in a part of the current collector coated with the electrode material, and a solid electrolyte coating step of coating a solid electrolyte on the current collector in which the hole portion is formed, and a cutting step of cutting the current collector coated with the solid electrolyte with a cutting line including the hole portion so that a concave portion is formed on the end face of the current collector. The present invention relates to a method for manufacturing a solid battery, which includes these steps in this order.

[0018] According to the invention of (6), an electrode plate having a solid electrolyte layer formed on at least a part of the end face can be efficiently manufactured, and the manufacturing cost of the solid battery can be reduced.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 3C

Figure 3D

Figure 4

Figure 5A

Figure 5B

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Figure 7A

Figure 7B

Figure 7C

Figure 7D

Figure 8

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Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0020] 《First Embodiment》 <Solid-state battery> FIG. 1 is a schematic cross-sectional view showing a solid-state battery 10 according to an embodiment of the present invention. As shown in FIG. 1, the solid-state battery 10 has a laminate 1 in which a plurality of positive electrode plates 20 and negative electrode plates 30 as electrode plates are alternately laminated. The laminate 1 is housed in an exterior body 5. The plurality of positive electrode plates 20 are electrically connected to the positive electrode 2, and the plurality of negative electrode plates 30 are electrically connected to the negative electrode 3. An insulator I is disposed around the positive electrode 2 and the negative electrode 3.

[0021] (Positive electrode plate) As shown in FIGS. 2 and 3A to 3D, the positive electrode plate 20 has a positive electrode current collector plate 21, a positive electrode active material layer 22 containing a positive electrode active material formed on the positive electrode current collector plate 21, a solid electrolyte layer 40 containing a solid electrolyte formed on the positive electrode active material layer 22, and a positive electrode tab 211 formed by extending the positive electrode current collector plate 21.

[0022] The positive electrode current collector plate 21 is not particularly limited and is composed of a known current collecting material that can be used for the positive electrode of a solid-state battery. For example, it is composed of aluminum, an aluminum alloy, stainless steel, nickel, iron, titanium, or the like.

[0023] The positive electrode active material constituting the positive electrode active material layer 22 is not particularly limited, and a known material that can occlude and release a charge transfer medium such as lithium ions can be appropriately selected and used. For example, lithium cobaltate, lithium nickelate, lithium manganate, hetero-element substituted Li-Mn spinel, lithium metal phosphate, lithium sulfide, sulfur, and the like can be mentioned. Specifically, LiCoO 2 , Li(Ni 5 / 10 Co 2 / 10 Mn 3 / 10 )O 2、 Li(Ni 6 / 10 Co 2 / 10 Mn 2 / 10 )O 2、 Li(Ni 8 / 10 Co 1 / 10 Mn 1 / 10 )O 2、 Li(Ni 0.8 Co 0.15 Al 0.05 )O 2、 Li(Ni 1 / 6Co 4 / 6 Mn 1 / 6 )O 2、 Li(Ni 1 / 3 Co 1 / 3 Mn 1 / 3 )O 2、 LiCoO 4 、LiMn 2 O 4 、LiNiO 2 、LiFePO 4 etc. may be mentioned. In the positive electrode active material layer 22, in addition to the positive electrode active material, optionally, a conductive assistant, a binder, etc. may be included.

[0024] (Negative electrode plate) As shown in FIGS. 2 and 3A to 3D, the negative electrode plate 30 includes a negative electrode current collector plate 31, a negative electrode active material layer 32 containing a negative electrode active material formed on the negative electrode current collector plate, a solid electrolyte layer 40 containing a solid electrolyte formed on the negative electrode active material layer 32, and a negative electrode tab 311 formed by extending the negative electrode current collector plate 31.

[0025] The negative electrode current collector plate 31 is not particularly limited and is composed of a known current collecting material that can be used for the negative electrode of a solid battery. For example, it is composed of nickel, copper or a copper alloy, stainless steel, etc.

[0026] The negative electrode active material constituting the negative electrode active material layer 32 is not particularly limited, and a known material that can occlude and release a charge transfer medium such as lithium ions can be appropriately selected and used. For example, lithium transition metal oxides such as lithium titanate, transition metal oxides such as TiO 2 、Nb 2 O 3 and WO 3 etc., Si, SiO, metal sulfides, metal nitrides, and carbon materials such as artificial graphite, natural graphite, graphite, soft carbon and hard carbon, and metal lithium, metal indium and lithium alloys, etc. may be mentioned. In the negative electrode active material layer 32, in addition to the negative electrode active material, optionally, a conductive assistant, a binder, etc. may be included.

[0027] The solid electrolyte layer 40 is a layer having a thickness of about several micrometers formed on the positive electrode active material layer 22 and the negative electrode active material layer 32, which are the lamination surfaces of the laminate 1, and is a layer containing at least a solid electrolyte material that is a solid or gel-like electrolyte. Through the above solid electrolyte material, charge transfer between the positive electrode active material and the negative electrode active material can be performed. The solid electrolyte material contained in the solid electrolyte layer 40 is not particularly limited, and for example, a sulfide solid electrolyte material, an oxide solid electrolyte material, a nitride solid electrolyte material, a halide solid electrolyte material, etc. can be used.

[0028] By forming the solid electrolyte layer 40 on the positive electrode active material layer 22 and the negative electrode active material layer 32, the thickness of the solid electrolyte layer 40 can be made about several micrometers, so that the stacking occupation ratio of the solid electrolyte can be reduced and the resistivity can be reduced. Further, due to the configuration described below, the solid-state battery 10 has the advantages that it can ensure insulation between electrodes while having a thin solid electrolyte layer, and can further simplify the manufacturing process and structure.

[0029] [Laminate] FIG. 2 is a diagram showing an overview of the laminate 1 according to the present embodiment. In the present embodiment, the area of the lamination surface of the positive electrode plate 20 as one electrode plate is larger than the area of the lamination surface of the negative electrode plate 30 as the other electrode plate. The outer edge of the positive electrode plate 20 is arranged outside the outer edge of the negative electrode plate 30 so as to include the outer edge of the negative electrode plate 30. Thereby, as shown in FIGS. 3A to 3C, an insulation distance L1 can be ensured between the end face of the positive electrode plate 20 and the end face of the negative electrode plate 30. In the following description, one electrode plate is described as the positive electrode plate 20 and the other electrode plate is described as the negative electrode plate 30, but one electrode plate may be the negative electrode plate and the other electrode plate may be the positive electrode plate.

[0030] A recess 23 is formed in the end face of the positive electrode plate 20 which is one electrode plate. As shown in FIG. 2, the recesses 23 are respectively arranged at positions corresponding to both ends of the negative electrode tab 311. The solid electrolyte layer 40 is formed on the end face of the recess 23. Thereby, an insulation distance L3 can be ensured between the portion of the positive electrode plate 20 excluding the recess 23 and the negative electrode tab 311.

[0031] As shown in FIG. 3C, the negative electrode tab 311 has a solid electrolyte layer 40 formed on the lamination surface with a certain length L2 in the tab extension direction. Thereby, an insulation distance L2 can be ensured between the negative electrode tab 311 and the end face of the positive electrode plate 20. On the other hand, since the negative electrode tab 311 does not have the solid electrolyte layer 40 on the end face, when the positive electrode plate 20 does not have the recess 23, the insulation distance on the intersection line between the end face of the negative electrode tab 311 and the end face of the positive electrode plate 20 cannot be ensured. However, in the present embodiment, as shown in FIG. 3D, the positive electrode plate 20 has a pair of recesses 23 in which the solid electrolyte layer 40 is formed in a range including the intersection line with the end face of the negative electrode tab 311, that is, at positions corresponding to both ends of the negative electrode tab 311. Therefore, insulation between the positive electrode plate 20 and the negative electrode tab 311 can be ensured.

[0032] <Method for manufacturing a solid-state battery> As shown in FIG. 11, the method for manufacturing a solid-state battery according to the present embodiment includes a positive electrode plate manufacturing step S1, a negative electrode plate manufacturing step S2, a lamination step S3, and a pressing step S4.

[0033] As shown in FIG. 11, the positive electrode plate manufacturing step S1 includes, in this order, an electrode material coating step S11, a drying step S12, a punching step S13, a solid electrolyte coating step S14, a drying step S15, and a cutting step 16.

[0034] As shown in FIG. 8, the electrode material coating step S11 is a step of forming a positive electrode active material layer 22 on both surfaces of the sheet-like positive electrode current collector 21. The method for forming the positive electrode active material layer 22 is not particularly limited. For example, a method of preparing a positive electrode composite material containing a positive electrode active material and applying the positive electrode composite material on a positive electrode current collector can be mentioned. The method of application is also not particularly limited, and examples include a doctor blade method, spray coating, screen printing, and the like. The drying step S12 is a step of drying the applied positive electrode composite material, and the drying method is not particularly limited.

[0035] The drilling step S13 is a step of forming holes in a sheet-like positive current collector plate 21 having positive electrode active material layers 22 formed on both sides. The method of forming the holes is not particularly limited, and conventionally known methods such as a method of performing drilling with a punching die and a method by laser processing can be used.

[0036] The solid electrolyte coating step S14 is a step of forming solid electrolyte layers 40 on both sides of a sheet-like positive current collector plate 21 having positive electrode active material layers 22 formed on both sides and having holes formed therein, as shown in FIG. 8. The method of forming the solid electrolyte layers 40 is not particularly limited, and examples thereof include methods of coating the solid electrolyte by a doctor blade method, spray coating, screen printing, etc., similar to the electrode material coating step S11. By coating the solid electrolyte on the positive current collector plate 21 having holes formed therein, the solid electrolyte can wrap around the end faces of the holes, and the solid electrolyte layers 40 can also be formed on the end faces of the holes. The drying step S15 is a step of drying the applied solid electrolyte layers 40, and the drying method is not particularly limited.

[0037] The cutting step S16 is a step of forming a positive electrode plate 20 having a recess 23 formed on the end face by cutting the sheet-like positive current collector plate 21 along a cutting line including the holes formed in the drilling step S13. Also, a positive electrode tab 211 is formed by the cutting step S16.

[0038] According to the positive electrode plate manufacturing step S1 having the above steps, a positive electrode plate 20 having a recess 23 formed on the end face and a solid electrolyte layer 40 formed on the end face of the recess 23 can be manufactured. That is, before cutting the sheet-like positive current collector plate 21, a positive electrode plate 20 having a solid electrolyte layer 40 formed on at least a part of the end face by coating the solid electrolyte on the end face of the hole can be manufactured, which is preferable from the viewpoint of the production efficiency of the positive electrode plate 20.

[0039] As shown in Fig. 11, the negative electrode plate manufacturing process S2 includes a pole material coating process S21, a drying process S22, a solid electrolyte coating process S23, a drying process S24, and a cutting process 25 in this order. Each process of the negative electrode plate manufacturing process S2 has the same processes as the positive electrode plate manufacturing process S1 except that it does not have the drilling process S13 as shown in Fig. 9.

[0040] The lamination process S3 is a process of laminating the positive electrode plate 20 manufactured by the positive electrode plate manufacturing process S1 and the negative electrode plate 30 manufactured by the negative electrode plate manufacturing process S2.

[0041] The pressing process S4 is a process of integrating the laminated positive electrode plate 20 and negative electrode plate 30 by sandwiching and pressing them with a press or the like.

[0042] Hereinafter, other embodiments of the present invention will be described. For configurations similar to those described above, the description may be omitted.

[0043] 《Second Embodiment》 Fig. 4 is a diagram showing an overview of the laminate 1a of the solid battery according to the second embodiment. The laminate 1a is formed by alternately laminating the positive electrode plate 20a and the negative electrode plate 30a. In the laminate 1a, the extending directions of the positive electrode tab 211 and the negative electrode tab 311 are directions away from each other. Except for the above, the configuration of the laminate 1a is the same as that of the laminate 1. The outer edge of the positive electrode plate 20a is arranged outside the outer edge of the negative electrode plate 30a so as to include the outer edge of the negative electrode plate 30a. Thereby, as shown in Figs. 5A and 5B, an insulation distance L1 can be ensured between the end face of the positive electrode plate 20a and the end face of the negative electrode plate 30a. A concave portion is formed on the end face of the positive electrode plate 20a, which is one of the electrode plates, and the concave portion is arranged at positions corresponding to both ends of the negative electrode tab 311 as shown in Fig. 4. Thus, the configuration of the present invention can be applied to solid batteries in which the extending directions of the tabs used for in-vehicle applications or the like are different.

[0044] 《Third Embodiment》 FIG. 6 is a diagram showing an overview of the laminate 1b of the solid-state battery according to the third embodiment. As shown in FIGS. 7A to 7D, the laminate 1b is formed by alternately laminating the positive electrode plates 20b and the negative electrode plates 30b. In the present embodiment, the solid electrolyte layer 40 is formed on the lamination surface of the positive electrode plate 20b, which is one of the electrode plates, but the solid electrolyte layer 40 is not formed on the lamination surface of the negative electrode plate 30b, which is the other electrode plate. In the following description, similar to the first embodiment, the configuration of the positive electrode plate 20b as one of the electrode plates and the configuration of the negative electrode plate 30b as the other electrode plate may be interchanged, with one of the electrode plates being the negative electrode plate and the other electrode plate being the positive electrode plate.

[0045] Similar to the first embodiment, the area of the lamination surface of the positive electrode plate 20b as one of the electrode plates is larger than the area of the lamination surface of the negative electrode plate 30b as the other electrode plate. The outer edge of the positive electrode plate 20b is disposed outside the outer edge of the negative electrode plate 30b so as to include the outer edge of the negative electrode plate 30b. Thereby, as shown in FIGS. 7A to 7D, an insulating distance L1 can be secured between the end surface of the positive electrode plate 20b and the end surface of the negative electrode plate 30b.

[0046] The negative electrode plate 30b does not have a solid electrolyte layer on its lamination surface. Therefore, as shown in FIG. 7C, no solid electrolyte layer is formed on the surface of the negative tab 311 either. For this reason, it is necessary to ensure insulation between the negative tab 311 and the positive electrode plate 20b.

[0047] A concave portion 23b is formed on the end surface of the positive electrode plate 20b, which is one of the electrode plates. The concave portion 23b is disposed at a position corresponding to the negative tab 311 as shown in FIG. 6. Different from the concave portion 23, the concave portion 23b is a single concave portion and is wider than the width of the negative tab 311. The solid electrolyte layer 40 is formed on the end surface of the concave portion 23b. The concave portion 23b can secure an insulating distance L3 between the portion of the positive electrode plate 20b excluding the concave portion 23b and the negative tab 311.

[0048] The positive electrode plate 20b has a concave portion 23b that is wider than the width of the negative tab 311, and the solid electrolyte layer 40 is formed on the end surface of the concave portion 23b as shown in FIG. 7C. Thereby, insulation between the positive electrode plate 20b and the negative tab 311 can be ensured.

[0049] The laminate 1b according to this embodiment can ensure insulation from the positive electrode plate 20b without forming a solid electrolyte layer on the surface of the negative electrode plate 30b. Thereby, the manufacturing process of the solid-state battery having the laminate 1b can be simplified.

[0050] <Manufacturing Method of Solid-State Battery> As shown in FIG. 12, the manufacturing method of the solid-state battery according to this embodiment includes a positive electrode plate manufacturing process S1, a negative electrode plate manufacturing process S2a, a lamination process S3, and a pressing process S4. The manufacturing method of the solid-state battery according to this embodiment includes the positive electrode plate manufacturing process shown in FIG. 10. The positive electrode plate manufacturing process shown in FIG. 10 is the same as the positive electrode plate manufacturing process S1 according to the first embodiment, except that the size of the hole formed by the drilling process S13 is large enough to form a recess 23b wider than the width of the negative electrode tab 311.

[0051] As shown in FIG. 12, the negative electrode plate manufacturing process according to this embodiment includes a negative electrode plate manufacturing process S2a. The negative electrode plate manufacturing process S2a is the same as the negative electrode plate manufacturing process S2 according to the first embodiment, except that it does not include a solid electrolyte coating process S23 and a drying process S24. Thereby, the manufacturing process of the solid-state battery can be simplified.

[0052] As shown in FIG. 12, the manufacturing method of the solid-state battery according to this embodiment includes a lamination process S3 and a pressing process S4 similar to those of the first embodiment.

[0053] As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, and those obtained by making appropriate modifications are also included in the scope of the present invention.

Explanation of Reference Numerals

[0054] 10 Solid-state battery 1, 1a, 1b Laminate 20, 20a, 20b Positive electrode plate (one of the electrode plates) 211 Positive electrode tab 23, 23b Recess 30, 30a, 30b Negative electrode plate (the other electrode plate) 311 Negative electrode tab (electrode tab) 40 Solid electrolyte layer

Claims

1. A solid-state battery including a laminate formed by alternately laminating a positive electrode plate and a negative electrode plate, wherein a solid electrolyte layer is formed on at least one of the lamination surfaces of the positive electrode plate and the negative electrode plate, the area of the lamination surface of one of the positive electrode plate and the negative electrode plate is larger than the area of the lamination surface of the other of the positive electrode plate and the negative electrode plate, and the outer edge of the one electrode plate is disposed outside the outer edge of the other electrode plate, a solid electrolyte layer is formed on the lamination surfaces of the positive electrode plate and the negative electrode plate, a concave portion is formed on an end surface of the one electrode plate, and the concave portion includes a pair of concave portions formed at positions corresponding to both ends of an electrode tab extending from the other electrode plate, a solid-state battery in which a solid electrolyte layer is formed only on the end surfaces of the concave portions among the end surfaces of the one electrode plate.

2. The concave portion includes a concave portion formed at a position corresponding to the electrode tab extending from the other electrode plate on the end surface of the one electrode plate and wider than the width of the electrode tab, The solid-state battery according to claim 1, wherein a solid electrolyte layer is formed on the lamination surface of the one electrode plate.

3. A method for manufacturing the solid-state battery according to claim 1, including a manufacturing process for an electrode for a solid-state battery, wherein the manufacturing process for the electrode for a solid-state battery includes a pole material coating step of coating an electrode material on a current collector plate, a drilling step of forming a hole portion in a part of the current collector plate coated with the electrode material, a solid electrolyte coating step of coating a solid electrolyte on the current collector plate in which the hole portion is formed, and a cutting step of cutting the current collector plate coated with the solid electrolyte along a cutting line including the hole portion so that the concave portion is formed on the end surface of the current collector plate, in this order.

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