Solid-state battery

Abstract

To provide a solid-state battery capable of enhancing volume efficiency by minimizing the volume occupied by the insulator relative to the battery's volume.SOLUTION: A solid-state battery has an electrode laminate having a cathode current collector, a cathode active material layer, an electrolyte layer, an anode active material layer, and an anode current collector, stacked. The end face of the electrode laminate has granular deposits, and an insulating layer is stacked onto the end face of the electrode laminate containing the deposits.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Patent Document 1 discloses an all-solid-state battery in which the side surfaces of an electrode stack are covered with an insulating film. The insulating film is arranged such that an extension portion extending beyond the end surface of the stack in the stacking direction is bent toward the end surface of the electrode stack. Patent Document 2 discloses that an insulator is disposed on the side of the laminate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-13729 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-162353 Summary of the Invention [Problem to be solved by the invention]

[0004] In the all-solid-state battery described in Patent Document 1, the insulating film is folded and covered to ensure adhesion, which results in a problem of a corresponding increase in the volume occupied by the insulating film, resulting in a decrease in volumetric efficiency (the smaller the ratio of the volume occupied by the insulating film (insulator) to the total volume of the battery, the higher the volumetric efficiency). Furthermore, in Patent Document 2, the insulator is formed thick, which also increases the volume occupied by the insulator and reduces the volumetric efficiency.

[0005] In view of the above problems, the present disclosure has an object to provide a solid-state battery capable of increasing volumetric efficiency by keeping the volume occupied by an insulator low relative to the volume of the battery. [Means for solving the problem]

[0006] The inventors have found that in a structure in which an insulator (insulating layer) is disposed on the end face of an electrode laminate, by improving the adhesion between the insulating layer and the electrode laminate, it is possible to eliminate the need for a folding portion or to make the insulating layer thinner, thereby improving volumetric efficiency. More specifically, they have found that by interposing minute granular deposits between the electrode laminate and the insulating layer, the adhesion between them is improved, and have completed the present invention.

[0007] The present application discloses a solid-state battery having an electrode laminate formed by laminating a positive electrode current collector, a positive electrode active material layer, an electrolyte layer, a negative electrode active material layer, and a negative electrode current collector, the solid-state battery having granular deposits on end surfaces of the electrode laminate, and an insulating layer laminated on the end surfaces of the electrode laminate including the deposits.

[0008] In the electrode laminate, when a laminate having a positive electrode current collector, a positive electrode active material layer, an electrolyte layer, a negative electrode active material layer, a negative electrode current collector, a negative electrode active material layer, an electrolyte layer, a positive electrode active material layer, and a positive electrode current collector in this order is used as a unit laminate, and when the thickness of the unit electrode laminate is D1 (mm) and the size of the attachment in the stacking direction of the unit electrode laminate is D2 (mm), the electrode laminate may be configured so that D2 / D1 is smaller than 0.112.

[0009] The deposits are particulate matter originating from at least one of the positive electrode active material layer, the negative electrode active material layer, and the electrolyte layer, and the size of the deposits in the stacking direction of the electrode stack may be less than 15 μm.

[0010] The thickness of the insulating layer may be 0.1 μm to 15 μm. [Effects of the Invention]

[0011] According to the solid-state battery of the present disclosure, by having granular attachments on the end surfaces of the electrode laminate, it is possible to increase the adhesion between the electrode laminate and the insulating layer only at the end surfaces of the electrode laminate and / or to make the insulating layer thinner, thereby improving volumetric efficiency. [Brief explanation of the drawings]

[0012] [Figure 1]1 is a schematic plan view of a solid state battery 10. FIG. [Figure 2] 1 is a cross-sectional view schematically illustrating the layer structure of a solid-state battery 10. FIG. [Figure 3] FIG. 3 is an enlarged view of a part of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0013] 1 to 3 show a schematic diagram of a solid-state battery 10 according to one embodiment. FIG. 1 is a plan view of the solid-state battery 10, and FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1. FIG. 3 is an enlarged view of the portion indicated by B in FIG. 2. For the sake of convenience, FIGS. 1 to 3 show only the components necessary for the explanation, and omit the battery case and the like. Here, the solid-state battery refers to both an all-solid-state battery in which the electrolyte is a solid electrolyte, and a semi-solid-state battery in which at least a portion of the electrolyte is a solid electrolyte and which also contains an electrolytic solution. The following description will be given using an all-solid-state battery as an embodiment.

[0014] As can be seen from FIGS. 1 to 3, the solid state battery 10 includes an electrode stack 20, an insulating layer 30, and an attachment 40.

[0015] 1. Electrode laminate The electrode laminate 20 is a battery element of the all-solid-state battery, and includes a positive electrode current collector 21, a positive electrode active material layer 22, an electrolyte layer 23, a negative electrode active material layer 24, and a negative electrode current collector 25. In this embodiment, the positive electrode current collector 21, the positive electrode active material layer 22, the electrolyte layer 23, the negative electrode active material layer 24, the negative electrode current collector 25, the negative electrode active material layer 24, the electrolyte layer 23, the positive electrode active material layer 22, and the positive electrode current collector 21 are laminated in this order to form a unit laminate body 20a. The electrode laminate 20 is formed by stacking a plurality of unit laminate bodies 20a.

[0016] 1.1. Positive electrode current collector The positive electrode current collector 21 is a conductive layer. Therefore, the positive electrode current collector 21 is made of a metal foil, a metal mesh, or the like. Among these, a metal foil is particularly preferable. Examples of metals that can be used to make the positive electrode current collector 21 include Ni, Cr, Au, Pt, Al, Fe, Ti, Zn, alloys thereof, and stainless steel. The positive electrode current collector 21 may have a coating layer on its surface to adjust electrical resistance. For example, it may be a carbon coating. The thickness of the positive electrode current collector 21 is not particularly limited, but is preferably 0.1 μm to 1 mm, and more preferably 1 μm to 100 μm, for example.

[0017] The positive electrode current collector 21 may include a positive electrode current collector tab (not shown). The positive electrode current collector tab allows the positive electrode current collector layers to be easily electrically connected in parallel. The positive electrode current collector tab may be made of the same material as the positive electrode current collector 21, or a different material. Furthermore, the positive electrode current collector tab may have the same thickness as the positive electrode current collector 21, or a different thickness.

[0018] 1.2. Positive electrode active material layer The positive electrode active material layer 22 is a layer containing at least a positive electrode active material. When the solid state battery 10 is an all-solid state battery, in addition to the positive electrode active material, it may further contain a solid electrolyte, a binder, a conductive additive, and the like. A known active material may be used as the positive electrode active material. Among known active materials, two materials with different potentials (charge / discharge potentials) at which predetermined ions are absorbed and released can be selected, and the material showing the more noble potential can be used as the positive electrode active material, and the material showing the more base potential can be used as the negative electrode active material. For example, when configuring a lithium ion battery, lithium cobalt oxide, lithium nickel oxide, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 Examples include various lithium-containing composite oxides such as O2, lithium manganate, and spinel-based lithium compounds. The surface of the positive electrode active material may be coated with an oxide layer such as a lithium niobate layer, a lithium titanate layer, or a lithium phosphate layer. The solid electrolyte is preferably an inorganic solid electrolyte, as it has higher ionic conductivity and superior heat resistance compared to organic polymer electrolytes. Examples of inorganic solid electrolytes include oxide solid electrolytes such as lithium lanthanum zirconate and sulfide solid electrolytes such as Li2S-P2S5. In particular, sulfide solid electrolytes containing Li2S-P2S5 are preferred, and sulfide solid electrolytes containing 50 mol% or more of Li2S-P2S5 are more preferred. Various binders such as butadiene rubber (BR), styrene butadiene rubber (SBR), acrylate butadiene rubber (ABR), and polyvinylidene fluoride (PVdF) can be used. As the conductive additive, carbon materials such as acetylene black and ketjen black, and metal materials such as nickel, aluminum, and stainless steel can be used. The content of each component in the positive electrode active material layer 22 and the shape of the positive electrode active material layer 22 may be the same as in the past. In particular, a sheet-shaped positive electrode active material layer 22 is preferred from the viewpoint of facilitating the construction of the solid state battery 10. In this case, the thickness of the positive electrode active material layer 22 is preferably, for example, 0.1 μm to 1 mm, and more preferably 1 μm to 150 μm.

[0019] 1.3. Electrolyte layer The electrolyte layer 23 is a layer containing at least an electrolyte. When the solid-state battery 10 is an all-solid-state battery, the electrolyte layer 23 can contain a solid electrolyte and, optionally, a binder. The solid electrolyte is preferably the inorganic solid electrolyte described above. The binder can be appropriately selected from the same binders as those used in the positive electrode active material layer 22. The content of each component in the electrolyte layer 23 and the shape of the electrolyte layer 23 may be the same as those of conventional ones. In particular, a sheet-like electrolyte layer 23 is preferred from the viewpoint of facilitating the construction of the solid-state battery 10. In this case, the thickness of the electrolyte layer 23 is preferably, for example, 0.1 μm to 1 mm, more preferably 1 μm to 100 μm, and even more preferably 1 μm to 15 μm.

[0020] 1.4.Negative electrode active material layer The negative electrode active material layer 24 is a layer containing at least a negative electrode active material. When the solid-state battery 10 is an all-solid-state battery, in addition to the negative electrode active material, it can further contain, optionally, a solid electrolyte, a binder, a conductive additive, and the like. Known active materials can be used as the active material. Among known active materials, two materials with different potentials (charge / discharge potentials) at which a predetermined ion is absorbed and released can be selected, and the material exhibiting the more noble potential can be used as the positive electrode active material, and the material exhibiting the more base potential can be used as the negative electrode active material. For example, when constructing a lithium-ion battery, carbon materials such as graphite and hard carbon, various oxides such as lithium titanate, Si and Si alloys, or metallic lithium and lithium alloys can be used as the negative electrode active material. The solid electrolyte, binder, and conductive additive may be selected appropriately from the same materials as those used in the positive electrode active material layer 22 .

[0021] The content of each component in the anode active material layer 24 and the shape of the anode active material layer 24 may be the same as in the past. In particular, from the viewpoint of facilitating the construction of the solid-state battery 10, a sheet-shaped anode active material layer 24 is preferred. In this case, the thickness of the anode active material layer 24 is preferably, for example, 0.1 μm to 1 mm, and more preferably 1 μm to 100 μm. However, it is preferable to determine the thickness of the anode active material layer 24 so that the capacity of the anode is greater than the capacity of the cathode.

[0022] 1.5. Negative electrode current collector The negative electrode current collector 25 is a current collector and may be made of a metal foil, a metal mesh, or the like. Metal foil is particularly preferred. Examples of metals that may form the negative electrode current collector 25 include Cu, Ni, Fe, Ti, Co, Zn, and stainless steel. The surface of the negative electrode current collector 25 may have some kind of coating layer for adjusting contact resistance. For example, it may be a carbon coating. The thickness of the negative electrode current collector 25 is not particularly limited. For example, it is preferably 0.1 μm to 1 mm, and more preferably 1 μm to 100 μm.

[0023] The negative electrode current collector 25 includes a negative electrode current collector tab 25a (see FIG. 1). The negative electrode current collector tab 25a allows the negative electrode current collector layers to be easily electrically connected in parallel. The negative electrode current collector tab 25a may be made of the same material as the negative electrode current collector 25, or a different material. Furthermore, the negative electrode current collector tab 25a may have the same thickness as the negative electrode current collector 25, or a different thickness.

[0024] 1.6. Unit Laminate In this embodiment, a unit laminate body 20a is formed by stacking a positive electrode current collector 21, a positive electrode active material layer 22, an electrolyte layer 23, a negative electrode active material layer 24, a negative electrode current collector 25, a negative electrode active material layer 24, an electrolyte layer 23, a positive electrode active material layer 22, and a positive electrode current collector 21 in this order. A plurality of unit laminate bodies 20a are stacked to form an electrode laminate body 20. Here, the size D1 (see FIG. 3) of one unit laminate body 20a in the stacking direction is not particularly limited, but can be, for example, about 130 μm to 150 μm.

[0025] 2. Insulation layer The insulating layer 30 is made of a layer of an insulator having electrical or ionic insulating properties. Preferably, the insulating layer 30 has electrical and ionic insulating properties. Such an insulating layer can be made of paper or a polymer such as polyimide.

[0026] 1 to 3, such insulating layers 30 are arranged so as to be laminated on the end faces (along the periphery) that form the thickness (direction in which each layer is laminated) of the electrode laminate 20. In this embodiment, as can be seen from FIG. 1, the insulating layers 30 are arranged on two long sides and one short side (the short side on which the negative electrode current collector tab 25a is not arranged) of the electrode laminate 20, which is rectangular in plan view. However, this is not limited to this, and insulating layers may be provided on only the long sides, only the short sides, only one side, or all sides except for the area of ​​the negative electrode current collector tab 25a.

[0027] The thickness of the insulating layer 30 (the size in the direction perpendicular to the direction in which the layers in the electrode stack 20 are stacked, T in FIG. 3) is not particularly limited, but can be 0.1 μm to 20 μm. From the viewpoint that a thinner thickness can improve volumetric efficiency, it is 15 μm or less, more preferably 10 μm or less.

[0028] When the insulating layer 30 is made of a polymer (resin), the insulating layer 30 can be formed by applying the resin before hardening to the end surface of the electrode laminate 20 and then hardening it by an appropriate method (e.g., heating or irradiating with light).

[0029] 3. Adhesion The deposits 40 are granular members. As can be seen from FIG. 3, the deposits 40 are disposed between the end faces of the electrode stack 20 and the insulating layer 30. By using such an attachment 40, the adhesion of the insulating layer 30 to the electrode stack 20 can be improved by having the attachment 40 on the end surface of the electrode stack 20 due to an anchor effect, etc., and it is possible to eliminate the need for a folded portion as in Patent Document 1, or to use a thinner insulating layer than in Patent Document 2, thereby improving volumetric efficiency.

[0030] The size of the attachment 40 is not particularly limited, but it is preferably small enough to prevent short circuits. Specifically, the size of the attachment 40 in the stacking direction of the electrode stack 20 (D2 (μm) in FIG. 3) is preferably smaller than the thickness of the electrolyte layer 23, and more preferably less than 15 μm. In addition, in relation to the thickness of the unit stack body 20a (D1 (μm) in FIG. 3), the ratio of D2 to D1, expressed as D2 / D1, is preferably less than 0.112. Although not particularly limited, D2 is preferably 1 μm or more from the viewpoint that effective adhesion (anchor effect) can be exhibited by having a certain size or more. Although not particularly limited, it is preferable that the shape of the attachment 40 is irregular, which can enhance the anchoring effect. However, the shape is not limited to this and may be spherical or oval.

[0031] Furthermore, the attachment 40 is preferably a particulate material resulting from (detached from) the positive electrode active material layer 22, the negative electrode active material layer 24, and the electrolyte layer 23 included in the electrode laminate 20. This allows for the use of cutting powder generated in the process of shaping the electrode laminate 20 by cutting (slicing) the electrode laminate 20 as the attachment. In other words, it is possible to reduce the time and effort required for the process of separately attaching the attachment to the end face of the electrode laminate and for removing the cutting powder generated. [Explanation of symbols]

[0032] 10...Solid-state battery, 20...Electrode laminate, 20a...Unit laminate, 21...Positive electrode current collector, 22...Positive electrode active material layer, 23...Electrolyte layer, 24...Anode active material layer, 25...Anode current collector, 30...Insulating layer, 40...Attachment

Claims

1. A solid-state battery having an electrode laminate in which a positive electrode current collector, a positive electrode active material layer, an electrolyte layer, a negative electrode active material layer, and a negative electrode current collector are laminated, The electrode stack has granular deposits on an end surface thereof, and an insulating layer is laminated on the end surface of the electrode stack including the deposits. solid state battery.

2. in the electrode laminate, a laminate having the positive electrode current collector, the positive electrode active material layer, the electrolyte layer, the negative electrode active material layer, the negative electrode current collector, the negative electrode active material layer, the electrolyte layer, the positive electrode active material layer, and the positive electrode current collector in this order is defined as a unit laminate; 2. The solid-state battery according to claim 1, wherein, when the thickness of the unit laminate body is D1 (mm) and the size of the attachment in the stacking direction of the unit laminate body is D2 (mm), D2 / D1 is smaller than 0.

112.

3. 2. The solid-state battery according to claim 1, wherein the attachment is a particulate matter originating from at least one of the positive electrode active material layer, the negative electrode active material layer, and the electrolyte layer, and the size of the attachment in the stacking direction of the electrode stack is less than 15 μm.

4. 4. The solid state battery according to claim 1, wherein the insulating layer has a thickness of 0.1 μm to 15 μm.

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