Solid battery

Abstract

To provide a solid-state battery capable of preventing short circuits and breakdown due to rolling in electrode layers of an individual solid-state battery when a laminated body is stacked and then processed by a high-pressure press.SOLUTION: A solid-state battery 101 includes a laminated body 11, in which a positive electrode collector 1, a positive electrode active material layer 2, a solid electrolyte layer 3, a negative electrode active material layer 4, and a negative electrode collector 5 are stacked in this order and a conductive rigid body 6 made of a conductive rigid body. The laminated bodies 11 and the conductive rigid bodies 6 are arranged in alternating layers, and the conductive rigid bodies 6 are arranged on the outermost two sides in the stacking direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a solid-state battery.

Background Art

[0002] In recent years, technologies related to solid-state batteries using solid electrolytes, which have a high energy density and high thermal safety, have been proposed. When a solid-state battery is used for applications that require a large current and high voltage, such as motor drive for electric vehicles or hybrid electric vehicles, a solid-state battery in which a plurality of single cells are combined and modularized is used.

[0003] Patent Document 1 discloses a configuration in which a laminate constituting a solid-state battery is housed in a laminate film as an exterior body, and a plurality of laminate-type solid-state batteries are combined to form a battery module.

[0004] Further, Patent Document 2 discloses a method for manufacturing a solid-state battery, in which a laminate in which a positive electrode layer having a positive electrode current collector and a positive electrode active material, a solid electrolyte layer, and a negative electrode layer having a negative electrode active material layer and a negative electrode current collector are laminated in this order is pressed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the solid-state battery described in Patent Document 1, a plurality of solid-state batteries are pressed and fixed by sandwiching them between plates. However, if the multi-layered cells of the solid-state battery are simply pressed at a high pressure, the electrode layers of the individual solid-state batteries may be short-circuited or destroyed by rolling.

[0007] In addition, when applying the manufacturing method of the solid battery described in Patent Document 2 to the manufacturing of the solid battery, after individually pressing a huge number of laminates and then laminating a predetermined number of them, these processes become bottlenecks and there is also a problem that the manufacturing capacity cannot be increased.

[0008] The present invention has been made in view of the above, and an object thereof is to provide a solid battery capable of suppressing short circuits and breakage due to rolling in the electrode layers of individual laminates when high-pressure pressing is performed after laminating the laminates.

Means for Solving the Problems

[0009] (1) To achieve the above object, the present invention provides a laminate in which a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector are laminated in this order, and a conductive rigid body made of a conductive rigid body. The solid battery is provided, wherein the laminate and the conductive rigid body are alternately laminated, and the conductive rigid body is disposed on both outermost sides in the lamination direction.

[0010] (2) Further, the present invention provides an assembly in which a pair of laminates in which a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector are laminated in this order are laminated so that the positive electrode current collectors are in contact with each other, and a conductive rigid body made of a conductive rigid body. The solid battery is provided, wherein the assembly and the conductive rigid body are alternately laminated, and the conductive rigid body is disposed on both outermost sides in the lamination direction.

[0011] (3) In the solid battery according to (1) or (2), the end portion of the positive electrode active material layer in the plane direction may be disposed inside the end portion of the adjacent solid electrolyte layer in the plane direction.

[0012] (4) The solid battery according to any one of (1) to (3) may further include an insulating spacer provided outside the positive electrode active material layer in the plane direction.

Effects of the Invention

[0013] According to the present invention, it is possible to provide a solid-state battery that can suppress short circuits and breakage due to rolling in the electrode layers of individual laminates when high-pressure pressing is performed after laminating the laminates.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

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Figure 6

Modes for Carrying Out the Invention

[0015] <First Embodiment> Hereinafter, the first embodiment of the present invention will be described with reference to the drawings. However, the embodiments shown below are examples of this embodiment, and the present invention is not limited to the following.

[0016] [Solid-State Battery] FIG. 1 is a cross-sectional exploded view showing the configuration of a solid-state battery 101 according to the first embodiment of the present invention. The solid-state battery 101 according to this embodiment includes a plurality of laminates 11 and a plurality of conductive rigid bodies 6 made of a conductive rigid body. As shown in FIG. 1, in the solid-state battery 101, the laminates 11 and the conductive rigid bodies 6 are alternately laminated, and the conductive rigid bodies 6 are arranged on both outermost sides in the lamination direction. That is, the solid-state battery 101 is manufactured by laminating the laminates 11 in a state of being sandwiched between the conductive rigid bodies 6 and then compressed.

[0017] (Laminate) The laminate 11 according to this embodiment is configured by laminating a positive electrode current collector 1, a positive electrode active material layer 2, a solid electrolyte layer 3, a negative electrode active material layer 4, and a negative electrode current collector 5 in this order. The positive electrode layer of the laminate 11 is composed of the positive electrode current collector 1 and the positive electrode active material layer 2, and the negative electrode layer is composed of the negative electrode active material layer 4 and the negative electrode current collector 5.

[0018] (Positive electrode layer) The positive electrode layer is a layer composed of at least the positive electrode active material layer 2 containing a positive electrode active material and the positive electrode current collector 1. As the positive electrode active material, a material capable of releasing and occluding a charge transfer medium can be appropriately selected and used. From the viewpoint of improving the charge transfer medium conductivity, a solid electrolyte may be optionally included. Also, a conductive aid may be optionally included to improve conductivity. Further, from viewpoints such as expressing flexibility, a binder may be optionally included. For the solid electrolyte, conductive aid, and binder, those generally used in solid-state batteries can be used.

[0019] The positive electrode active material can be the same as those used in the positive electrode layer of a general solid-state battery and is not particularly limited. For example, in the case of a lithium-ion battery, a layered active material containing lithium, a spinel-type active material, an olivine-type active material, etc. can be mentioned. Specific examples of the positive electrode active material include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), LiNi p Mn q Co r O2 (p + q + r = 1), LiNi p Al q Co r O2 (p + q + r = 1), lithium manganate (LiMn2O4), hetero-element-substituted Li-Mn spinel represented by Li1 + xMn2 - x - yMyO4 (x + y = 2, M = at least one selected from Al, Mg, Co, Fe, Ni, and Zn), lithium titanate (oxide containing Li and Ti), lithium metal phosphate (LiMPO4, M = at least one selected from Fe, Mn, Co, and Ni), etc. can be mentioned.

[0020] The positive electrode current collector 1 is not particularly limited as long as it has a function of collecting current of the positive electrode layer, and examples thereof include aluminum, aluminum alloy, stainless steel, nickel, iron, and titanium. Among them, aluminum, aluminum alloy, and stainless steel are preferable. Further, examples of the shape of the positive electrode current collector include a foil shape and a plate shape.

[0021] In the laminate 11 according to the present embodiment, it is preferable that the end portion of the positive electrode active material layer 2 in the plane direction is arranged inside the plane direction than the end portion of the adjacent solid electrolyte layer 3 in the plane direction. Thereby, short circuit can be more reliably suppressed.

[0022] (Solid electrolyte layer) The solid electrolyte layer 3 is a layer laminated between the positive electrode layer and the negative electrode layer, and is a layer containing at least a solid electrolyte material. Charge transfer medium conduction between the positive electrode active material and the negative electrode active material can be performed through the solid electrolyte material contained in the solid electrolyte layer.

[0023] The solid electrolyte material is not particularly limited as long as it has charge transfer medium conductivity, and examples thereof include sulfide solid electrolyte materials, oxide solid electrolyte materials, nitride solid electrolyte materials, halide solid electrolyte materials, etc. Among them, sulfide solid electrolyte materials are preferable. This is because the charge transfer medium conductivity is higher than that of oxide solid electrolyte materials.

[0024] Examples of the sulfide solid electrolyte material include Li2S-P2S5, Li2S-P2S5-LiI, etc. in the case of a lithium ion battery. The description of "Li2S-P2S5" means a sulfide solid electrolyte material formed using a raw material composition containing Li2S and P2S5, and the same applies to other descriptions.

[0025] On the other hand, examples of the oxide solid electrolyte material include NASICON type oxides, garnet type oxides, perovskite type oxides, etc. in the case of a lithium ion battery. Examples of the NASICON type oxide include oxides containing Li, Al, Ti, P, and O (e.g., Li1.5 Al 0.5 Ti 1.5 (PO4)3) can be cited. As the garnet-type oxide, for example, an oxide containing Li, La, Zr, and O (for example, Li7La3Zr2O 12 ) can be cited. As the perovskite-type oxide, for example, an oxide containing Li, La, Ti, and O (for example, LiLaTiO3) can be cited.

[0026] (Negative electrode layer) The negative electrode layer is a layer composed of at least a negative electrode active material layer 4 containing a negative electrode active material and a negative electrode current collector 5. From the viewpoint of improving the charge transfer medium conductivity, it may optionally contain a solid electrolyte. Also, for improving conductivity, it may optionally contain a conductive aid. Further, from the viewpoint of exhibiting flexibility, etc., it may optionally contain a binder. For the solid electrolyte, conductive aid, and binder, those generally used in solid batteries can be used.

[0027] The negative electrode active material is not particularly limited as long as it can occlude and release a charge transfer medium. For example, in the case of a lithium-ion battery, lithium transition metal oxides such as lithium titanate (Li4Ti5O 12 ), transition metal oxides such as TiO2, Nb2O3, and WO3, metal sulfides, metal nitrides, and carbon materials such as graphite, soft carbon, and hard carbon, and metal lithium, metal indium, and lithium alloys, etc. can be cited. Also, the negative electrode active material may be in powder form or in thin film form.

[0028] The negative electrode current collector 5 is not particularly limited as long as it has a function of collecting current of the negative electrode layer. Examples of the material of the negative electrode current collector include nickel, copper, and stainless steel, etc. Also, examples of the shape of the negative electrode current collector include foil shape, plate shape, etc.

[0029] (Conductive rigid body) A plurality of conductive rigid bodies 6 are used to sandwich a plurality of laminates 11. Further, by using a material having conductivity as the conductive rigid body 6, the conductive rigid body 6 electrically connects between the plurality of laminates 11. When the laminate 11 and the conductive rigid body 6 are alternately laminated and the conductive rigid bodies 6 are arranged on both outermost sides in the lamination direction, short circuits and breakages due to rolling can be suppressed in the electrode layers (positive electrode layer, negative electrode layer) of the individual laminates 11 when the solid battery 101 is press-processed.

[0030] The material of the conductive rigid body 6 is not particularly limited as long as it is a material having conductivity, but it is preferably a metal material, and particularly preferably stainless steel (SUS). The size of the conductive rigid body 6 is preferably larger in the planar direction than the electrode layer of the laminate 11 facing the conductive rigid body 6. The thickness of the conductive rigid body 6 is preferably several hundred μm.

[0031] [Manufacturing method] The manufacturing method of the solid battery 101 according to the present embodiment will be described below. However, the solid battery 101 according to the present embodiment can be manufactured with appropriate modifications within the scope of the object of the present invention.

[0032] (Manufacturing method of positive electrode layer) The positive electrode layer can be manufactured by disposing a positive electrode mixture containing a positive electrode active material on the surface of the positive electrode current collector 1. As the manufacturing method of the positive electrode layer, the same method as the conventional method can be used, and the positive electrode can be manufactured by either a wet method or a dry method. Hereinafter, the case of manufacturing the positive electrode by the wet method will be described.

[0033] The positive electrode layer is manufactured by a process of obtaining a positive electrode active material paste containing a positive electrode active material and a solvent, and a process of applying the positive electrode active material paste onto the surface of the positive electrode current collector 1 and drying it to form a positive electrode active material layer 2 on the surface of the positive electrode current collector 1. For example, a positive electrode active material paste can be obtained by mixing and dispersing a positive electrode active material in a solvent. The solvent used in this case is not particularly limited and may be appropriately selected according to the properties of the positive electrode active material, solid electrolyte, etc. For example, a non-polar solvent such as heptane is preferable. For the mixing and dispersion of the positive electrode active material and the solvent, various mixing and dispersion devices such as an ultrasonic dispersion device, a shaker, and a Filmix (registered trademark) can be used. The solid content in the positive electrode active material paste is not particularly limited.

[0034] By applying the thus obtained positive electrode active material paste onto the surface of the positive electrode current collector 1 and drying it to form a positive electrode active material layer 2 on the surface of the positive electrode current collector 1, a positive electrode layer can be obtained. As a means for applying the positive electrode paste onto the surface of the positive electrode current collector 1, known coating means such as a doctor blade can be used. The total thickness (the thickness of the positive electrode) of the dried positive electrode active material layer 2 and the positive electrode current collector 1 is not particularly limited, but for example, from the viewpoints of energy density and lamination properties, 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. Further, the positive electrode may be optionally produced through a pressing process. Also, the positive electrode layer may be manufactured by applying the positive electrode active material paste onto the surface of a resin film, drying it to form a positive electrode active material layer 2, and peeling off the resin film. In this case, it is preferable to previously apply a release agent to the resin film.

[0035] (Method for manufacturing a solid electrolyte layer) The solid electrolyte layer 3 can be manufactured, for example, through processes such as pressing a solid electrolyte. Alternatively, the solid electrolyte layer 3 can also be manufactured through a process of applying a solid electrolyte paste, which is prepared by dispersing a solid electrolyte or the like in a solvent, onto the surface of a substrate or an electrode. The solvent used in this case is not particularly limited and may be appropriately selected according to the properties of the binder and the solid electrolyte. The thickness of the solid electrolyte layer 3 varies greatly depending on the configuration of the battery. 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.

[0036] (Method for manufacturing the negative electrode layer) Similar to the positive electrode layer, the negative electrode layer can be manufactured, for example, by putting a negative electrode active material or the like into a solvent and then dispersing it with an ultrasonic disperser or the like to obtain a negative electrode mixture paste, applying the paste onto the surface of the negative electrode current collector 5, and then drying it. The solvent used in this case is not particularly limited and may be appropriately selected according to the properties of the negative electrode active material or the like. The thickness of the negative electrode layer is preferably, for example, 0.1 μm or more and 1 mm or less, and more preferably 1 μm or more and 100 μm or less. Also, the negative electrode can be manufactured through a pressing process. The negative electrode mixture paste can be applied onto the surface of a resin film and dried to form a negative electrode active material layer 4, and then the resin film can be peeled off to manufacture the negative electrode layer. In this case, it is preferable to apply a release agent to the resin film in advance.

[0037] (Method for manufacturing the laminate) In this embodiment, for example, there is a step of manufacturing the laminate 11 by laminating the above positive electrode layer, the solid electrolyte layer 3, and the negative electrode layer in this order. As for the lamination method, a known method can be adopted. Also, at this time, the manufactured laminate 11 may be subjected to a pressing process.

[0038] By having the step of pressing the laminate 11, the adhesion of the laminate 11 is improved. As the means for pressing, general methods such as uniaxial or biaxial pressing and roll pressing can be used. When pressing, it is preferable to press until the interfaces of each layer are joined and in a dense state.

[0039] (Method for manufacturing a solid-state battery) The solid-state battery 101 according to the present embodiment includes, for example, a plurality of conductive rigid bodies 6 and a plurality of laminates 11. After the laminates 11 are laminated in a state of being sandwiched between the conductive rigid bodies 6, they are manufactured by being pressurized at a high pressure. As the means for pressing, general methods such as uniaxial or biaxial pressing and roll pressing can be used. When pressing, it is preferable to press until the conductive rigid body 6 and the laminate 11 are in a dense state.

[0040] According to the solid-state battery 101 according to the present embodiment, the following effects are achieved. That is, in the solid-state battery 101 according to the present embodiment, the laminates 11 and the conductive rigid bodies 6 are alternately laminated, and the conductive rigid bodies 6 are arranged on both outermost sides in the lamination direction. As a result, when the laminates 11 are laminated and then subjected to a pressing process, since all the laminates 11 are sandwiched by the conductive rigid bodies 6, it is possible to suppress short circuits and breakage due to rolling in the electrode layers of the individual laminates 11. Here, FIG. 5 is an exploded cross-sectional view of a conventional solid-state battery 201. In the conventional solid-state battery 201, the laminates 21 are continuously arranged at the center in the lamination direction, and since both sides of the laminate 11 are not sandwiched by the conductive rigid bodies 6, short circuits and breakage due to rolling occur in the electrode layer, but according to the present embodiment, this can be suppressed.

[0041] <Second Embodiment> Next, a second embodiment of the present invention will be described with reference to the drawings. Regarding the configurations common to the first embodiment, the description thereof will be omitted as appropriate. However, the following embodiments are illustrative of the present embodiment, and the present invention is not limited to the following.

[0042] [Solid-state battery] FIG. 2 is a cross-sectional view showing the configuration of the solid-state battery 102 according to the second embodiment of the present invention. The solid-state battery 102 according to the present embodiment is different from the solid-state battery 101 according to the first embodiment in that an insulating spacer 7 is provided on the outer side in the plane direction of the positive electrode active material layer 2, and other configurations are the same as those of the first embodiment.

[0043] (Insulating spacer 7) The insulating spacer 7 is installed on the outer side in the plane direction of the positive electrode active material layer 2 of the laminate 12 and electrically insulates between the positive electrode layer and the negative electrode layer of the laminate 12. The insulating spacer 7 is not particularly limited as long as it is an insulating material, and known materials can be applied. By providing the insulating spacer 7 on the outer side in the plane direction of the positive electrode layer constituting the laminate 12, when a plurality of laminates 12 are laminated and then high-pressure pressed to manufacture the solid-state battery 102, suppression of short circuits due to destruction of the electrode layer becomes more reliable. This insulating spacer 7 can be installed by fabricating the laminate 12 by a manufacturing method similar to the manufacturing method of the laminate 11 described in the first embodiment and then inserting it between the solid electrolyte layer 3 from the outer side in the plane direction of the positive electrode active material layer 2. Alternatively, similar to the formation of the positive electrode active material layer 2, it is also possible to form the insulating spacer 7 by applying a paste containing the constituent material of the insulating spacer 7 and drying it.

[0044] According to the solid-state battery 102 according to the present embodiment, the same effects as those of the first embodiment are achieved. In addition, since the insulating spacer 7 is provided on the outer side in the plane direction of the positive electrode active material layer 2, when the laminate 12 is laminated and then high-pressure pressed, suppression of short circuits of the electrode layer due to rolling becomes more reliable.

[0045] <Third Embodiment> Next, the third embodiment of the present invention will be described with reference to the drawings. The description of the configurations common to the first and second embodiments will be appropriately omitted. However, the following embodiments are examples of the present embodiment, and the present invention is not limited to the following.

[0046] [Solid-state battery] FIG. 3 is a cross-sectional view showing the configuration of the solid-state battery 103 according to the third embodiment of the present invention. The solid-state battery 103 according to the present embodiment is different from the solid-state battery 101 according to the first embodiment in that it includes an aggregate 13 formed by laminating a pair of laminates having the same configuration as the laminate 11 of the first embodiment such that the positive electrode current collectors 1 are in contact with each other, and in that the aggregate 13 and the conductive rigid body 6 are alternately laminated. Other configurations are the same as those of the first embodiment.

[0047] (Aggregate) As described above, the aggregate 13 according to the present embodiment is formed by laminating a pair of laminates in which a positive electrode current collector 1, a positive electrode active material layer 2, a solid electrolyte layer 3, a negative electrode active material layer 4, and a negative electrode current collector 5 are laminated in this order such that the positive electrode current collectors 1 are in contact with each other. The aggregate 13 is produced by joining the positive electrode current collectors of the pair of laminates described above, and a conventionally known method can be adopted as the joining method.

[0048] According to the solid-state battery 103 according to the present embodiment, the same effects as those of the first embodiment are achieved. Here, FIG. 6 is an exploded cross-sectional view of a conventional solid-state battery 202. In the conventional solid-state battery 202, an aggregate 22 is continuously arranged at the center in the stacking direction, and both sides of the aggregate 22 are not sandwiched by the conductive rigid body 6. Therefore, when a short circuit or breakage due to rolling occurs in the electrode layer, this can be suppressed according to the present embodiment. Further, according to the present embodiment, since the solid-state battery 103 includes an aggregate 13 formed by laminating a pair of laminates in which a positive electrode current collector 1, a positive electrode active material layer 2, a solid electrolyte layer 3, a negative electrode active material layer 4, and a negative electrode current collector 5 are laminated in this order such that the positive electrode current collectors 1 are in contact with each other, an increase in output power due to direct connection of the electrode layers can be expected.

[0049] <Fourth Embodiment> Next, a fourth embodiment of the present invention will be described with reference to the drawings. The description of the configurations common to the first to third embodiments will be appropriately omitted. However, the following embodiments are examples of the present embodiment, and the present invention is not limited to the following.

[0050] [Solid-state battery] FIG. 4 is a cross-sectional view showing the configuration of a solid-state battery 104 according to a fourth embodiment of the present invention. The solid-state battery 104 according to the present embodiment is different from the solid-state battery 103 according to the third embodiment in that an insulating spacer 7 is provided on the outer side in the plane direction of the positive electrode active material layer 2, and other configurations are the same as those of the third embodiment. The insulating spacer 7 has the same configuration as the insulating spacer 7 of the second embodiment.

[0051] According to the solid-state battery 104 according to the present embodiment, the effects of the first to third embodiments are further enhanced.

[0052] The present invention is not limited to the above embodiments, and modifications and improvements within the scope that can achieve the object of the present invention are included in the present invention.

Description of Reference Numerals

[0053] 1 Positive electrode current collector 2 Positive electrode active material layer 3 Solid electrolyte layer 4 Negative electrode active material layer 5 Negative electrode current collector 6 Conductive rigid body 7 Insulating spacer 11, 12, 21, 22 Laminated body 13, 14 Aggregate 101, 102, 103, 104 Solid-state battery

Claims

1. A laminate comprising one positive electrode current collector, one positive electrode active material layer, one solid electrolyte layer, one negative electrode active material layer, and one negative electrode current collector, wherein the positive electrode current collector, the positive electrode active material layer, the solid electrolyte layer, the negative electrode active material layer, and the negative electrode current collector are laminated in this order and configured; and a conductive metal material; wherein one of the laminates and the conductive metal material are alternately laminated, and the conductive metal material is disposed on both outermost sides in the lamination direction; a solid battery, wherein the size of the conductive metal material is larger in the planar direction than the electrode layer of a single laminate facing the conductive metal material.

2. The solid battery according to claim 1, wherein an end portion of the positive electrode active material layer in the planar direction is disposed inside the end portion of the adjacent solid electrolyte layer in the planar direction.

3. The solid battery according to claim 1 or 2, further comprising an insulating spacer provided outside the positive electrode active material layer in the planar direction.

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