Solid-state battery

Abstract

In one embodiment of the present application, a solid-state battery is provided. The solid-state battery is characterized by having at least one cell configuration unit along a stacking direction, the cell configuration unit having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer, the positive electrode layer and the negative electrode layer each including at least an active material layer, and having a side portion, the side portion having a terminal connection portion and a terminal non-connection portion, at least a portion of the terminal non-connection portion of at least one of the positive electrode layer and the negative electrode layer being surrounded by an insulating portion or a solid electrolyte portion in a plan view, the terminal non-connection portion having a contact region in direct contact with the insulating portion or the solid electrolyte portion and a non-contact region not in direct contact with the insulating portion or the solid electrolyte portion.

Description

Technical Field

[0001] This invention relates to a solid-state battery. Background Technology

[0002] Rechargeable batteries have long been used for various purposes. For example, they are used as power sources for electronic devices such as smartphones and laptops.

[0003] In this type of secondary battery, liquid electrolytes, such as organic solvents, have traditionally been used as the medium for ion movement. However, secondary batteries using liquid electrolytes suffer from problems such as electrolyte leakage. Therefore, solid-state batteries, which use solid electrolytes instead of liquid electrolytes, are being developed.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2007-5279 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] The solid-state battery 500' is configured as follows: at least one battery unit 100' is provided along the stacking direction, and the battery unit 100' has a positive electrode layer 10A', a negative electrode layer 10B' facing each other, and a solid electrolyte layer 20' between the positive electrode layer 10A' and the negative electrode layer 10B' (see reference). Figure 4 ).

[0009] The positive electrode layer 10A' comprises a positive current collector 11A' and a positive active material layer 12A', with one end of the positive current collector 11A' electrically connected to the positive terminal 200A'. The negative electrode layer 10B' comprises a negative current collector 11B' and a negative active material layer 12B', with one end of the negative current collector 11B' electrically connected to the negative terminal 200B'. In this configuration, the solid electrolyte layer 20' is sometimes disposed without gap between the opposing positive electrode layers 10A' and negative electrode layers 10B', and is disposed in contact with the side portion 30' (excluding the terminal connection portion) of each electrode layer (see reference). Figure 4 ).

[0010] As is known to those skilled in the art, during the charging of the solid-state battery 500', as ions move in the solid electrolyte between the positive electrode layer 10A' and the negative electrode layer 10B', the active material layer of each electrode layer expands due to the active material material that constitutes it (see reference). Figure 5 The following problems may arise during the expansion of this active material layer.

[0011] Specifically, when the active material layer expands during charging of the solid-state battery 500', the solid electrolyte layer 20', which is in contact with the sides 30' (excluding the terminal connection portions) of each electrode layer, expands less. Therefore, stress caused by the expansion of the active material layer is generated between the sides 30' (excluding the terminal connection portions) of each electrode layer and the solid electrolyte layer 20', on the side of the solid electrolyte layer 20' where the expansion is less. If this stress occurs, cracks 40' may be generated at the periphery of the solid-state battery 500', specifically at the periphery of the solid electrolyte layer 20' (see reference). Figure 6 as well as Figure 7 Because of this crack 40', moisture from the outside may penetrate into the electrode layer and solid electrolyte inside the solid battery 500', causing battery deterioration. Therefore, it becomes difficult to properly charge and discharge the solid battery 500'.

[0012] The present invention was made in view of this situation. That is, the main object of the present invention is to provide a solid battery capable of appropriately suppressing cracking during charging.

[0013] Technical solutions for solving technical problems

[0014] To achieve the above objectives, in one embodiment of the present invention, a solid-state battery is provided.

[0015] The battery has at least one battery unit along the stacking direction. The battery unit includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer.

[0016] The positive electrode layer and the negative electrode layer each include at least an active material layer and have a side portion, which is formed by a terminal connection portion and a terminal non-connection portion.

[0017] When viewed from above, at least a portion of the non-connected portion of the terminal of at least one of the positive electrode layer and the negative electrode layer is surrounded by an insulating portion or a solid electrolyte portion. The non-connected portion of the terminal has a contact area that is in direct contact with the insulating portion or the solid electrolyte portion and a non-contact area that is not in direct contact with the insulating portion or the solid electrolyte portion.

[0018] Invention Effects

[0019] According to one embodiment of the present invention, cracking of solid-state batteries during charging can be appropriately suppressed. Attached Figure Description

[0020] Figure 1 This is an exploded perspective view schematically representing a solid-state battery according to one embodiment of the present invention.

[0021] Figure 2 This is an exploded perspective view schematically representing a solid-state battery according to one embodiment of the present invention.

[0022] Figure 3 This is an exploded perspective view schematically representing a solid-state battery according to one embodiment of the present invention.

[0023] Figure 4 It is a schematic cross-sectional view representing an existing solid-state battery.

[0024] Figure 5 This is a schematic cross-sectional view of an existing solid-state battery having an active material layer that expands during charging.

[0025] Figure 6 This is a schematic cross-sectional view of an existing solid-state battery having a solid electrolyte layer that cracks during charging.

[0026] Figure 7 This is a schematic top view of an existing solid-state battery having a solid electrolyte layer that cracks during charging. Detailed Implementation

[0027] Before describing a solid-state battery according to one embodiment of the present invention, the basic structure of a solid-state battery will be described first. In this specification, "solid-state battery" broadly refers to a battery whose constituent elements are made of solids, and narrowly refers to an all-solid-state battery whose constituent elements (especially all constituent elements) are made of solids. In a preferred embodiment, the solid-state battery of the present invention is a stacked solid-state battery in which layers that form battery constituent units are stacked together, preferably such layers are made of sintered bodies. The term "solid-state battery" in this specification includes not only secondary batteries capable of repeated charging and discharging, but also primary batteries capable only of discharging. In one embodiment of the present invention, the solid-state battery is a secondary battery. The term "secondary battery" is not overly limited to this name; for example, it may also include energy storage devices.

[0028] The term "sectional observation" as used in this specification refers to the state of a solid-state battery when viewed from a direction substantially perpendicular to the thickness direction based on the stacking direction of the active material layers constituting the solid-state battery. The terms "up-down direction" and "left-right direction," used directly or indirectly in this specification, correspond to the up-down and left-right directions in the figures, respectively. Unless otherwise stated, the same symbols or designations denote the same parts or locations or have the same meaning. In a preferred embodiment, it can be understood that the vertical direction pointing downwards (i.e., the direction of gravity) corresponds to the "downward direction," and its opposite direction corresponds to the "upward direction."

[0029] Unless otherwise stated, the various numerical ranges mentioned in this specification are intended to include both the lower and upper limits of the values ​​themselves. That is, taking the numerical range of 1 to 10 as an example, unless otherwise stated, it can be understood to include the lower limit value "1" as well as the upper limit value "10".

[0030] [The structure of a solid-state battery]

[0031] A solid-state battery is composed of at least two electrode layers, a positive electrode and a negative electrode, and a solid electrolyte. Specifically, a solid-state battery is composed of a battery element comprising a battery constituent unit, which is composed of a positive electrode layer, a negative electrode layer, and a solid electrolyte therebetween.

[0032] In the case of solid-state batteries, when the constituent layers are formed by firing, the positive electrode layer, negative electrode layer, and solid electrolyte form a sintered layer. Preferably, the positive electrode layer, negative electrode layer, and solid electrolyte are fired together integrally, so that the battery element forms a single sintered body.

[0033] The positive electrode layer is an electrode layer comprising at least a positive electrode active material. The positive electrode layer may further comprise a solid electrolyte. For example, the positive electrode layer is composed of a sintered body comprising at least positive electrode active material particles and solid electrolyte particles. In a preferred embodiment, the positive electrode layer is composed of a sintered body substantially comprising only positive electrode active material particles and solid electrolyte particles. On the other hand, the negative electrode layer is an electrode layer comprising at least a negative electrode active material. The negative electrode layer may further comprise a solid electrolyte. For example, the negative electrode layer is composed of a sintered body comprising at least negative electrode active material particles and solid electrolyte particles. In a preferred embodiment, the negative electrode layer is composed of a sintered body substantially comprising only negative electrode active material particles and solid electrolyte particles.

[0034] Positive and negative electrode active materials are substances that participate in electron exchange in a solid-state battery. Charge and discharge occur through the movement (conduction) of ions between the positive and negative electrode layers via the solid electrolyte. The positive and negative electrode layers are particularly preferably layers capable of intercalating or deintercalating lithium ions or sodium ions. That is, the solid-state battery is preferably an all-solid-state secondary battery in which lithium ions move between the positive and negative electrode layers via the solid electrolyte for charge and discharge.

[0035] (Positive electrode active material)

[0036] Examples of positive electrode active materials included in the positive electrode layer include at least one selected from the group consisting of lithium phosphate compounds with a NASICON-type structure, lithium phosphate compounds with an olivine-type structure, lithium-containing layered oxides, and lithium-containing oxides with a spinel-type structure. Examples of lithium phosphate compounds with a NASICON-type structure include Li3V2(PO4)3. Examples of lithium phosphate compounds with an olivine-type structure include Li3Fe2(PO4)3, LiFePO4, and / or LiMnPO4. Examples of lithium-containing layered oxides include LiCoO2 and / or LiCo. 1 / 3 Ni 1 / 3 Mn 1 / 3 O2, etc. Examples of lithium-containing oxides with a spinel-type structure include LiMn2O4 and / or LiNi. 0.5 Mn 1.5 O4, etc.

[0037] In addition, as a positive electrode active material capable of intercalating and deintercalating sodium ions, at least one can be selected from the group consisting of sodium phosphate compounds having a NASICON-type structure, sodium phosphate compounds having an olivine-type structure, sodium-containing layered oxides, and sodium-containing oxides having a spinel-type structure.

[0038] (Negative electrode active material)

[0039] Examples of negative electrode active materials included in the negative electrode layer include at least one element selected from the group consisting of oxides containing at least one element selected from the group consisting of Ti, Si, Sn, Cr, Fe, Nb, and Mo; graphite-lithium compounds; lithium alloys; lithium phosphate compounds with a NASICON-type structure; lithium phosphate compounds with an olivine-type structure; and lithium oxides with a spinel-type structure. Li-Al is an example of a lithium alloy. Li3V2(PO4)3 and / or LiTi2(PO4)3 are examples of lithium phosphate compounds with a NASICON-type structure. Li3Fe2(PO4)3 and / or LiCuPO4 are examples of lithium phosphate compounds with an olivine-type structure. Li4Ti5O is an example of a lithium oxide with a spinel-type structure. 12 wait.

[0040] In addition, as a negative electrode active material capable of intercalating and deintercalating sodium ions, at least one can be selected from the group consisting of sodium phosphate compounds having a NASICON-type structure, sodium phosphate compounds having an olivine-type structure, and sodium oxides having a spinel-type structure.

[0041] It should be noted that, in a preferred embodiment of the solid-state battery of the present invention, the positive electrode layer and the negative electrode layer are made of the same material.

[0042] The positive and / or negative electrode layers may contain conductive materials. Examples of conductive materials included in the positive and negative electrode layers include at least one metal such as silver, palladium, gold, platinum, aluminum, copper, and nickel, as well as carbon. While not particularly limited, carbon is preferred because it is difficult to react with the positive electrode active material, the negative electrode active material, and the solid electrolyte material, thus effectively reducing the internal resistance of the solid-state battery.

[0043] Furthermore, the positive and / or negative electrode layers may contain sintering aids. Examples of sintering aids include at least one selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, boron oxide, silicon oxide, bismuth oxide, and phosphorus oxide.

[0044] (Positive current collector / Negative current collector)

[0045] Although not essential elements of the electrode layer, the positive and negative electrode layers can each have a positive current collector and a negative current collector, respectively. The positive and negative current collectors can each be in the form of foils, but from the viewpoint of reducing the manufacturing cost and internal resistance of solid-state batteries through integral firing, they can also be in the form of sintered bodies. Materials with high conductivity are preferably used for the positive and negative current collectors, such as silver, palladium, gold, platinum, aluminum, copper, and nickel. In particular, copper is less reactive with the positive and negative active materials and the solid electrolyte material, thus reducing the internal resistance of the solid-state battery, and is therefore preferred. The positive and negative current collectors can also each have an electrical connection portion for external electrical connection, configured to be electrically connected to terminals. The positive and negative current collectors can each be in the form of foils. From the viewpoint of improving electronic conductivity and reducing manufacturing costs through integral firing, it is preferable that the positive and negative current collectors each have an integrally fired form. It should be noted that when the positive and negative current collectors have a fired body form, they can, for example, be composed of a fired body containing a conductive material and a sintering aid. The conductive material contained in the positive and negative current collectors can, for example, be selected from the same conductive materials that can be contained in the positive and / or negative electrode layers. The sintering aid contained in the positive and negative current collectors can, for example, be selected from the same sintering aids that can be contained in the positive and / or negative electrode layers.

[0046] The thickness of the positive current collector and the negative current collector is not particularly limited. For example, they can be 1 μm or more and 5 μm or less, especially 1 μm or more and 3 μm or less.

[0047] The thickness of the positive electrode layer and the negative electrode layer is not particularly limited. For example, they can be 2 μm or more and 50 μm or less, especially 5 μm or more and 30 μm or less.

[0048] (Solid electrolyte)

[0049] Solid electrolytes are materials capable of conducting lithium ions. Especially in solid-state batteries, solid electrolytes form the battery cells, creating a layer between the positive and negative electrode layers capable of conducting lithium or sodium ions. It should be noted that the solid electrolyte must at least be disposed between the positive and negative electrode layers. That is, the solid electrolyte can also exist around the positive and / or negative electrode layers, extending from between them. Specific examples of solid electrolytes include lithium phosphate compounds with a NASICON structure, oxides with a perovskite structure, and oxides with garnet-type or garnet-like structures. Examples of lithium phosphate compounds with a NASICON structure include Li... x M y (PO4)3 (1≤x≤2, 1≤y≤2, M is at least one selected from the group consisting of Ti, Ge, Al, Ga and Zr). As an example of a lithium phosphate compound having a NASICON structure, Li can be cited as an example. 1.2 Al 0.2 Ti 1.8 (PO4)3, etc. As an example of oxides with a perovskite structure, La can be cited. 0.55 Li 0.35 TiO3, etc. As an example of oxides with garnet-type or garnet-like structures, Li7La3Zr2O can be cited. 12 wait.

[0050] It should be noted that solid electrolytes capable of conducting sodium ions include, for example, sodium-phosphate compounds with a NASICON structure, oxides with a perovskite structure, and oxides with garnet-type or garnet-like structures. Among sodium-phosphate compounds with a NASICON structure, Na... x M y (PO4)3 (1≤x≤2, 1≤y≤2, M is at least one selected from the group consisting of Ti, Ge, Al, Ga and Zr).

[0051] Solid electrolytes may also contain sintering aids. The sintering aids contained in solid electrolytes may be selected from the same materials that may be contained in the positive and negative electrode layers.

[0052] The thickness of the solid electrolyte layer is not particularly limited; for example, it can be greater than 1 μm and less than 15 μm, especially greater than 1 μm and less than 5 μm.

[0053] (terminal)

[0054] Solid-state batteries typically include terminals (e.g., external electrodes). Specifically, terminals are provided on the sides of the solid-state battery. Specifically, terminals on the positive electrode side, connected to the positive electrode layer, and terminals on the negative electrode side, connected to the negative electrode layer, are provided on the sides of the solid-state battery. The terminals of the positive electrode layer are engaged with the ends of the positive electrode layer, specifically with leads formed at the ends of the positive electrode layer. Similarly, the terminals of the negative electrode layer are engaged with the ends of the negative electrode layer, specifically with leads formed at the ends of the negative electrode layer. In a preferred embodiment, from the viewpoint of engaging with the leads of the electrode layers, the terminals preferably contain glass or glass-ceramic. Furthermore, the terminals preferably contain a material with high conductivity. There are no particular limitations on the specific material of the terminals, but examples include at least one selected from the group consisting of silver, gold, platinum, aluminum, copper, tin, and nickel.

[0055] (Outer packaging)

[0056] The outer packaging is a component that can generally be formed on the outermost side of a solid-state battery, serving to provide electrical, physical, and / or chemical protection. The preferred materials for the outer packaging are those with excellent insulation, durability, and / or moisture resistance, and are environmentally safe.

[0057] The outer packaging is a layer that covers the surface of the battery element in a way that allows the leads of each electrode layer to be individually engaged with each external electrode. Specifically, the outer packaging covers the surface of the battery element in a way that allows the leads of the positive electrode layer to be engaged with the external electrodes on the positive electrode side, and simultaneously covers the surface of the battery element in a way that allows the leads of the negative electrode layer to be engaged with the external electrodes on the negative electrode side. That is, the outer packaging does not cover the entire surface of the battery element without gaps, but rather covers the battery element in a way that exposes the leads (ends of the electrode layers) of the electrode layers so that they can be engaged with the external electrodes.

[0058] [Characteristics of the solid-state battery of the present invention]

[0059] Based on the basic structure of a solid-state battery, the following describes the characteristic features of a solid-state battery according to one embodiment of the present invention.

[0060] The inventors of this application have conducted in-depth research on solutions for appropriately suppressing cracking during the charging of solid-state batteries. As a result, the inventors of this application have proposed a characteristic configuration in which the contact area between the non-connected portion of the electrode layer (excluding the connected portion) and the solid electrolyte portion or insulating portion surrounding the non-connected portion of the terminal is constructed in a manner not previously known.

[0061] It should be noted that, in this specification, "insulating portion" refers to a part made of insulating material that does not contain active material, and therefore expands less than the active material (layer) during charging of the solid-state battery. "Solid electrolyte portion" refers to a part made of solid electrolyte material with a relatively low content of active material, and therefore expands less than the active material (layer) during charging of the solid-state battery. "Terminal connection portion" refers to the portion where the side of the electrode layer connects to the terminal. "Terminal non-connection portion" refers to the portion where the side of the electrode layer is not connected to the terminal.

[0062] The following describes in detail, using the accompanying drawings, the configuration of a feature portion of a solid-state battery according to an embodiment of the present invention. It should be noted that, as described below, an embodiment of the present invention is based on a configuration in which at least a portion of the non-connected terminal portions on the sides of the positive and negative electrode layers, when viewed from above, is surrounded by an insulating portion or a solid electrolyte portion. In this specification, "side portion of the electrode layer (positive electrode layer / negative electrode layer)" may correspond to the outer edge and / or contour portion of the electrode layer when viewed from above.

[0063] Figure 1 This is an exploded perspective view schematically representing a solid-state battery according to one embodiment of the present invention.

[0064] like Figure 1 As shown, in one embodiment of the present invention, a solid-state battery 500I includes at least one battery constituent unit 100I along the stacking direction. The battery constituent unit 100I includes a positive electrode layer 10AI, a negative electrode layer 10BI, and a solid electrolyte layer 20I between the positive electrode layer 10AI and the negative electrode layer 10BI. The positive electrode layer 10AI includes a positive electrode active material layer, and the negative electrode layer 10BI includes a negative electrode active material layer.

[0065] The positive electrode layer 10AI includes a main face (or main portion) 13AI that is opposite to the solid electrolyte layer 20I in the stacking direction, and a side portion 14AI (14I) extending in a direction substantially perpendicular to the extending direction of the main face. The side portion 14AI has a terminal connection portion 15AI (15I) and a terminal non-connection portion 16AI (16I). The terminal connection portion 15AI of the side portion 14AI of the positive electrode layer 10AI is the portion that can be directly connected to the positive terminal. The terminal non-connection portion 16AI of the side portion 14AI of the positive electrode layer 10AI is the portion that is not connected to the positive terminal.

[0066] The negative electrode layer 10BI includes a main face (or main portion) 13BI that is opposite to the solid electrolyte layer 20I in the stacking direction, and a side portion 14BI (14I) extending in a direction substantially perpendicular to the extending direction of the main face. The side portion 14BI has a terminal connection portion 15BI (15I) and a terminal non-connection portion 16BI (16I). The terminal connection portion 15BI of the side portion 14BI of the negative electrode layer 10BI is the portion that can be directly connected to the negative terminal. The terminal non-connection portion 16BI of the side portion 14BI of the negative electrode layer 10BI is the portion that is not connected to the negative terminal.

[0067] As described above, one embodiment of the present invention is based on the premise that at least a portion of the terminal non-connection portion 16I on the side of the electrode layer (positive electrode layer / negative electrode layer) is surrounded by an insulating portion or a solid electrolyte portion 50I when viewed from above. Under this premise, when viewed from the electrode layer 10I along the direction of the insulating portion or solid electrolyte portion 50I, a technical feature of one embodiment of the present invention is that the terminal non-connection portion 16I of at least one of the positive electrode layer 10A1 and the negative electrode layer 10B1 has a contact area 17I that directly contacts the insulating portion or solid electrolyte portion 50I, and a non-contact area 18I that does not directly contact the insulating portion or solid electrolyte portion 50I.

[0068] The phrase "at least a portion of the non-connecting portion of the terminal is surrounded by an insulating portion or a solid electrolyte portion" as used in this specification refers to a state in which the insulating portion or solid electrolyte portion surrounds all or a portion of the non-connecting portion of the terminal on the side of the electrode layer (positive electrode layer / negative electrode layer) when viewed from above, including a non-contact area that is not in direct contact with the insulating portion or solid electrolyte portion. Furthermore, the term "contact area" as used in this specification refers to a constituent element of the non-connecting portion of the terminal on the side of the electrode layer, specifically the area that is in direct contact with the insulating portion or solid electrolyte portion surrounding a portion of the non-connecting portion of the terminal on the electrode layer when viewed from above. Conversely, the term "non-contact area" as used in this specification refers to a constituent element of the non-connecting portion of the terminal on the side of the electrode layer, specifically the area that is not in direct contact with the insulating portion or solid electrolyte portion surrounding a portion of the non-connecting portion of the terminal on the electrode layer when viewed from above. That is, neither the aforementioned "contact area" nor "non-contact area" is a constituent element of the terminal connection portion on the side of the electrode layer.

[0069] In the existing configuration, when viewed from above, the non-connected portion of the terminal on the side of the electrode layer is in contact with the insulating portion or the solid electrolyte portion, and is completely surrounded by the insulating portion or the solid electrolyte portion. That is, when the non-connected portion of the terminal is completely surrounded by the insulating portion or the solid electrolyte portion, the non-connected portion of the terminal consists only of the contact area that is in direct contact with the insulating portion or the solid electrolyte portion.

[0070] In contrast, according to the technical features of the present invention, the terminal non-connection portion 16I of the side portion 14I of the electrode layer 10I includes a non-contact area 18I that does not directly contact the insulating portion or the solid electrolyte portion 50I. This reduces the contact range between the terminal non-connection portion 16I and the insulating portion or the solid electrolyte portion 50I. Specifically, it reduces the contact range between the electrode layer 10I, which contains an active material layer with a large degree of expansion, and the insulating portion or the solid electrolyte portion 50I with a small degree of expansion. This provides locations where stress is generated on the side of the insulating portion or the solid electrolyte portion 50I with a small degree of expansion due to the active material layer with a large degree of expansion, as well as locations where stress is not generated or is difficult to generate.

[0071] As a result, compared to the existing configuration described above, the range of stress generated on the insulating portion or solid electrolyte portion 50I side due to the large expansion of the active material layer can be reduced. By reducing this stress range, the stress itself generated on the insulating portion or solid electrolyte portion 50I side due to the large expansion of the active material layer can be mitigated compared to the existing configuration described above. Therefore, the occurrence of cracks during charging of the solid battery 500I (500) can be appropriately suppressed.

[0072] It should be noted that one preferred embodiment of the present invention is as follows.

[0073] In one embodiment, it is preferable that, when viewed from above, the non-connected portion 16I of the terminal is partially surrounded by an insulating portion or a solid electrolyte portion 50I (see reference). Figure 1 ).

[0074] The phrase "the non-connected portion of the terminal is partially surrounded by the insulating portion or the solid electrolyte portion" as used in this specification means that, when viewed from above, the non-connected portion of the terminal on the side of the electrode layer (positive electrode layer / negative electrode layer) is not completely surrounded by the insulating portion or the solid electrolyte portion, or a portion of the non-connected portion of the terminal is not surrounded by the insulating portion or the solid electrolyte portion.

[0075] In this case, such as Figure 1 As shown, in the non-contact area 18I of the terminal non-connection portion 16I, a configuration can be provided in which the terminal non-connection portion 16I and the insulating portion or solid electrolyte portion 50I do not directly contact each other and are not opposite each other. From another point of view, a configuration can be adopted in which at least two insulating portions or solid electrolyte portions 50I that are separated from each other when viewed from above surround the terminal non-connection portion 16I. That is, this means that when viewed from above, the insulating portion or solid electrolyte portion 50I surrounding at least a portion of the terminal non-connection portion 16I becomes discontinuous.

[0076] According to this method, in the non-contact area 18I of the terminal non-connection portion 16I, the terminal non-connection portion 16I and the insulating portion or solid electrolyte portion 50I are not in direct contact, thus forming a configuration where the two are not opposed. Therefore, regardless of whether the electrode layer 10I expands before or after battery charging, contact between the non-contact area 18I and the insulating portion or solid electrolyte portion 50I can be appropriately suppressed. This provides suitable locations where stress is generated on the side of the insulating portion or solid electrolyte portion 50I with less expansion due to the active material layer with a large degree of expansion, as well as locations where such stress does not occur or is difficult to generate.

[0077] In one embodiment, it is preferable that a non-contact region 18II is disposed between adjacent contact regions 17II and another contact region 17II in the terminal non-connection portion 16II of electrode layer 10II (see reference). Figure 2 ).

[0078] In one embodiment of the invention, an insulating portion or solid electrolyte portion 50II surrounds the terminal non-connection portion 16II of the electrode layer 10II. This insulating portion or solid electrolyte portion 50II also has the advantage of protecting the electrode layer 10II and ensuring electronic insulation. Therefore, it is preferable to achieve stress relief while simultaneously protecting the electrode layer and ensuring electronic insulation by introducing a non-contact region 18II in the terminal non-connection portion 16II. From this viewpoint, it is preferable to arrange the non-contact region 18II between adjacent contact regions 17II.

[0079] In one approach, it is preferable that at least two non-contact areas are separated by a predetermined interval and configured separately (see reference). Figure 1 ).

[0080] As described above, according to one embodiment of the present invention, the terminal non-connection portion 16I of the side portion 14I of the electrode layer 10I can have a contact area 17I that directly contacts the insulating portion or the solid electrolyte portion 50I and a non-contact area 18I that does not directly contact the insulating portion or the solid electrolyte portion 50I. This non-contact area 18I can help reduce the contact range between the terminal non-connection portion 16I of the side portion 14I of the electrode layer 10I and the insulating portion or the solid electrolyte portion 50I. From the viewpoint of increasing the contribution to reducing this contact range, it is preferable to increase the number of non-contact areas 18I.

[0081] Specifically, the number of non-contact areas 18I is not limited to one, but preferably at least two (or more) (see reference). Figure 1 Therefore, compared to the case where the number of non-contact areas is one, the contact range between the terminal non-connection portion 16I and the insulating portion or solid electrolyte portion 50I can be further reduced. As a result, it becomes possible to further reduce the range of stress generated on the side of the insulating portion or solid electrolyte portion 50I with a smaller degree of expansion due to the active material layer with a large degree of expansion.

[0082] In one approach, as described above, these at least two non-contact areas 18II are more preferably configured regularly (refer to...). Figure 2 ).

[0083] As can be seen from the above, when at least two non-contact areas 18II are separated by a predetermined interval, the contact range between the terminal non-connection portion 16II and the insulating portion or solid electrolyte portion 50II can be further reduced compared to the case where the number of non-contact areas is one.

[0084] In this regard, when at least two non-contact regions 18II, which are components of the terminal non-connection portion 16II, are regularly arranged, the contact region 17II is also regularly arranged. Thus, it is possible to regularly provide portions where stress will occur on the insulating portion or solid electrolyte portion 50II side and portions where stress is not generated or is difficult to generate.

[0085] As a result, the tendency for stress to occur in the insulating or solid electrolyte portion 50II is suppressed, thus preventing uneven distribution of stress. Consequently, overall, stress mitigation is achieved uniformly and in a balanced manner. Therefore, the occurrence of cracks during charging of the solid-state battery 500II can be more effectively suppressed.

[0086] In one embodiment, viewed from above, at least two non-contact areas 18II are preferably arranged opposite each other (see reference). Figure 2 ).

[0087] As described above, if at least two non-contact areas 18II are arranged separately at a predetermined interval, the contact range between the terminal non-connection portion 16II and the insulating portion or solid electrolyte portion 50II can be further reduced compared to the case where the number of non-contact areas is one.

[0088] Regarding this, when at least two non-contact regions 18II, which are components of the terminal non-connection portion 16II, are arranged opposite each other when viewed from above, areas where stress is not generated or is difficult to generate on the insulating portion or solid electrolyte portion 50II side can also be arranged opposite each other. That is, this means that stress-relieving portions are opposite each other. As a result, compared to the case where at least two non-contact regions 18II are arranged laterally on the same side at a predetermined interval, the stress-relieving portions are not unevenly distributed on one side. Therefore, overall, stress relief can be achieved uniformly and well. Therefore, the occurrence of cracks during charging of the solid battery 500II can be more appropriately suppressed.

[0089] In one embodiment, provided that at least two non-contact regions 18II are separately configured, it is preferable that the contact region 17II, which is in direct contact with the insulating part or the solid electrolyte part 50II, and the non-contact region 18II, which is not in direct contact with the insulating part or the solid electrolyte part 50II, are alternately configured (see reference). Figure 2 ).

[0090] As can be seen from the above, if at least two non-contact areas 18II are separated by a predetermined interval and arranged separately, the contact range between the terminal non-connection portion 16II and the insulating portion or solid electrolyte portion 50II can be further reduced compared to the case where the number of non-contact areas is one.

[0091] Regarding this point, the greater the number of non-contact areas 18II, the more the contact range between the terminal non-connection portion 16II and the insulating portion or solid electrolyte portion 50II can be further reduced, which can help alleviate overall stress. However, this is not necessarily good from the viewpoint of protecting the electrode layer and ensuring electronic insulation. Therefore, by alternately arranging the aforementioned contact areas 17II and the aforementioned non-contact areas 18II, a specified number / quantity of contact areas 17II can be ensured, and the insulating portion or solid electrolyte portion 50II can be ensured to have a discontinuous form when viewed from above. Thus, overall, it is possible to more appropriately balance (1) stress alleviation, (2) protection of the electrode layer, and (3) ensuring electronic insulation.

[0092] Furthermore, similarly, from the viewpoint of appropriately balancing stress relief, electrode layer protection, and ensuring electronic insulation, it is preferable to limit the proportion of the non-contact area 18II within the terminal non-connection portion 16II to a specified range, which also ensures the contact area 17II to a certain extent. From this viewpoint, the ratio of the area of ​​the non-contact area 18II, which is not in direct contact with the insulating portion or solid electrolyte portion 50II, to the total area of ​​the terminal non-connection portion 16II can be 0.05 or more and 0.3 or less. Thus, the range of the aforementioned non-contact area 18II is limited, and the contact area 17II can be ensured to a certain extent, thereby appropriately protecting the electrode layer and ensuring electronic insulation.

[0093] In one embodiment, under top-down viewing, the non-contact regions 18I, 18III are preferably located at the corners 60I, 60III of the electrode layers 10I, 10III (see reference). Figure 1 as well as Figure 3 ).

[0094] During battery charging, the insulating portion or solid electrolyte portion does not extend significantly relative to the expansion of the electrode layers, thus generating stress. The corners or vicinity of the electrode layers 10I and 10III, where stress is most difficult to disperse due to their curved shape when viewed from above, are particularly prone to concentration. From this perspective, it is preferable to provide non-contact regions 18I and 18III at the corners 60I and 60III of the electrode layers 10I and 10III. This eliminates the need for insulating or solid electrolyte portions to surround the corners of the electrode layers where stress tends to concentrate. As a result, the stress generated on the insulating or solid electrolyte portion side can be more appropriately mitigated overall. Therefore, the occurrence of cracks during charging of the solid batteries 500I and 500III can be more appropriately suppressed.

[0095] [Method for manufacturing a solid-state battery according to the present invention]

[0096] The following describes a method for manufacturing a solid-state battery according to one embodiment of the present invention. It should be noted that this manufacturing method is merely an example, and it is explained in advance that other methods (such as screen printing) may be used.

[0097] A solid-state battery according to one embodiment of the present invention can be manufactured using a green sheet method that primarily utilizes green sheets. In one embodiment, after forming a predetermined laminate using the green sheet method, a solid-state battery according to one embodiment of the present invention can finally be manufactured. It should be noted that the following description is based on this method, but is not limited thereto; the predetermined laminate can also be formed using methods such as screen printing.

[0098] (The process of forming unfired laminates)

[0099] First, a paste for a solid electrolyte layer, a paste for a positive electrode active material layer, a paste for a positive electrode current collector layer, a paste for a negative electrode active material layer, a paste for a negative electrode current collector layer, a paste for an insulating layer, and a paste for a protective layer are coated on each substrate (e.g., PET film).

[0100] Each paste can be prepared by wet mixing a predetermined constituent material of each layer, appropriately selected from the group consisting of a positive electrode active material, a negative electrode active material, a conductive material, a solid electrolyte material, an insulating material, and a sintering aid, with an organic carrier obtained by dissolving an organic material in a solvent. The paste for the positive electrode active material layer, for example, includes a positive electrode active material, a conductive material, a solid electrolyte material, an organic material, and a solvent. The paste for the negative electrode active material layer, for example, includes a negative electrode active material, a conductive material, a solid electrolyte material, an organic material, and a solvent. As a paste for the positive electrode current collector layer / negative electrode current collector layer, for example, at least one material selected from the group consisting of silver, palladium, gold, platinum, aluminum, copper, and nickel can be used. The paste for the solid electrolyte layer, for example, includes a solid electrolyte material, a sintering aid, an organic material, and a solvent. The paste for the protective layer, for example, includes an insulating material, an organic material, and a solvent. The paste for the insulating layer, for example, includes an insulating material, an organic material, and a solvent.

[0101] In wet mixing, a medium can be used; specifically, ball milling or adhesive milling can be used. On the other hand, wet mixing methods without a medium can be used, such as sand milling, high-pressure homogenizer method, or kneading dispersion method.

[0102] A paste for a specified solid electrolyte layer can be prepared by wet mixing of a specified solid electrolyte material and a sintering aid, and by dissolving an organic material in a solvent to obtain an organic carrier. It should be noted that, as mentioned above, examples of solid electrolyte materials include lithium phosphate compounds with a NASICON structure, oxides with a perovskite structure, and oxides with a garnet-type or garnet-like structure. Examples of lithium phosphate compounds with a NASICON structure include Li... x M y (PO4)3 (1≤x≤2, 1≤y≤2, M is at least one selected from the group consisting of Ti, Ge, Al, Ga and Zr). As an example of a lithium phosphate compound having a NASICON structure, Li can be cited as an example. 1.2 Al 0.2 Ti 1.8 (PO4)3, etc. As an example of oxides with a perovskite structure, La can be cited. 0.55 Li 0.35 TiO3, etc. As an example of oxides with garnet-type or garnet-like structures, Li7La3Zr2O can be cited. 12 wait.

[0103] The positive electrode active material included in the paste for the positive electrode active material layer is, for example, at least one selected from the group consisting of lithium phosphate compounds having a NASICON-type structure, lithium phosphate compounds having an olivine-type structure, lithium-containing layered oxides, and lithium-containing oxides having a spinel-type structure.

[0104] The insulating material included in the paste for the insulating layer may be, for example, composed of glass materials, ceramic materials, etc. The insulating material included in the paste for the protective layer is preferably, for example, at least one selected from the group consisting of glass materials, ceramic materials, thermosetting resin materials, and photocurable resin materials.

[0105] The organic material contained in the paste is not particularly limited, and at least one polymeric material selected from the group consisting of polyvinyl alcohol acetal resin, cellulose resin, polyacrylic acid resin, polyurethane resin, polyvinyl acetate resin, and polyvinyl alcohol resin can be used. The solvent is not particularly limited as long as it can dissolve the aforementioned organic material; for example, toluene and / or ethanol can be used.

[0106] The negative electrode active material included in the paste used as the negative electrode active material layer is, for example, an oxide selected from the group consisting of at least one element selected from the group consisting of at least one element selected from the group consisting of Ti, Si, Sn, Cr, Fe, Nb and Mo, a graphite-lithium compound, a lithium alloy, a lithium phosphate compound having a NASICON-type structure, a lithium phosphate compound having an olivine-type structure, and a lithium oxide having a spinel-type structure.

[0107] As a sintering aid, it can be at least one selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, boron oxide, and silicon oxide.

[0108] The coated paste is dried on a hot plate heated to 30–50°C, thereby forming solid electrolyte layer sheets, positive electrode sheets, and negative electrode sheets of specified thicknesses on a substrate (e.g., PET film).

[0109] Next, each sheet is peeled off from the substrate. After peeling, the sheets of each component of the battery unit are sequentially stacked along the lamination direction.

[0110] During this lamination stage, a solid electrolyte sheet or an insulating sheet is screen-printed onto the side region of the electrode sheet. Specifically, the solid electrolyte sheet or insulating sheet is formed to surround the non-connected portion of the electrode sheet's side surface, excluding the portion where terminals will be connected later. In particular, in one embodiment of the invention, the solid electrolyte sheet or insulating sheet is formed by screen printing such that a portion of the non-connected portion of the electrode sheet's outer edge is in direct contact with the solid electrolyte sheet or insulating sheet, while the remaining portion is not in contact with the solid electrolyte sheet or insulating sheet.

[0111] Next, hot pressing is preferably performed using a specified pressure (e.g., about 50 to about 100 MPa), followed by isotropic pressing using a specified pressure (e.g., about 150 to about 300 MPa). This allows the formation of a specified laminate.

[0112] (Firing process)

[0113] The resulting laminate is then fired. This firing is carried out by heating in a nitrogen atmosphere, for example, at 600°C to 1000°C.

[0114] Next, terminals are mounted on the resulting laminate. The terminals are configured to be electrically connected to both the positive and negative electrode layers, respectively. For example, the terminals are preferably formed by sputtering or the like. Although not particularly limited, the terminals are preferably made of at least one material selected from silver, gold, platinum, aluminum, copper, tin, and nickel. Furthermore, a protective layer is preferably formed by sputtering, spraying, or the like to a degree that does not cover the terminals.

[0115] Therefore, it is possible to properly manufacture a solid-state battery according to one embodiment of the present invention.

[0116] In a solid-state battery according to one embodiment of the present invention, compared with the conventional case where the non-connected portion of the electrode layer on the side of the electrode layer is in contact with the insulating portion or the solid electrolyte portion and is completely surrounded by the insulating portion or the solid electrolyte portion when viewed from above, it is possible to provide a region in the non-connected portion of the terminal where the insulating portion or the solid electrolyte portion is not directly in contact with the active material layer, which is a component of the electrode layer.

[0117] Therefore, compared to the existing configuration described above, the contact area between the electrode layer, including the active material layer with a large degree of expansion, and the insulating portion or solid electrolyte portion with a small degree of expansion can be reduced. Consequently, compared to the case where the non-connected portion of the electrode layer's side terminal is completely surrounded by the insulating portion or solid electrolyte portion when viewed from above, it is possible to provide areas where stress is generated on the side of the insulating portion or solid electrolyte portion with a small degree of expansion due to the active material layer with a large degree of expansion, as well as areas where such stress does not occur or is difficult to generate.

[0118] As a result, compared to the existing configuration described above, the range of stress generated on the insulating or solid electrolyte side, where the active material layer expands significantly, can be reduced. By reducing this stress generation range, the overall stress generated on the insulating or solid electrolyte side, where the active material layer expands significantly, can be mitigated compared to the existing configuration described above. Therefore, the occurrence of cracks during solid-state battery charging can be appropriately suppressed.

[0119] The foregoing has described one embodiment of the present invention, but it is merely a typical example illustrating the scope of the invention. Therefore, those skilled in the art will readily understand that the present invention is not limited thereto and various modifications are permissible.

[0120] Industrial availability

[0121] The solid-state battery according to one embodiment of the present invention can be applied to various fields of envisioned energy storage. Although only illustrative, the solid-state battery according to one embodiment of the present invention can be applied to the following fields: electrical, information, and communication fields using mobile devices such as mobile phones, smartphones, smartwatches, laptops, and mobile devices such as digital cameras, activity meters, ARM computers, and electronic paper; home and small industrial applications (such as power tools, golf carts, and home, care, and industrial robots); large industrial applications (such as forklifts, elevators, and port cranes); transportation systems (such as hybrid vehicles, electric vehicles, buses, trams, electric-assisted bicycles, and electric motorcycles); power systems (such as various power generation systems, load conditioners, smart grids, and general household energy storage systems); medical applications (such as medical devices like headphones and hearing aids); pharmaceutical applications (such as medication management systems); and the Internet of Things (IoT) field; space and deep-sea applications (such as space probes and underwater research vessels).

[0122] Explanation of reference numerals in the attached figures

[0123] 10I, 10II, 10III: Electrode layers; 10AI, 10AII, 10AIII, 10A': Positive electrode layers; 10BI, 10BII, 10BIII, 10B': Negative electrode layers; 12A': Positive electrode active material layer; 12B': Negative electrode active material layer; 14I, 14II, 14III: Side portions of electrode layers; 14AI, 14AII, 14AIII: Side portions of positive electrode layers; 14BI, 14BII, 14BIII: Side portions of negative electrode layers; 15I, 15II, 15III: Electrode terminal connection portions; 15AI, 15AII, 15A III: Positive terminal connection portion; 15BI, 15BII, 15BIII: Negative terminal connection portion; 16I, 16II, 16III: Non-connected portion of electrode terminals; 16AI, 16AII, 16AIII: Non-connected portion of positive terminal; 16BI, 16BII, 16BIII: Non-connected portion of negative terminal; 17I, 17II, 17III: Contact area directly in contact with the insulating part or solid electrolyte part, which are components of the non-connected portion of the electrode terminals; 17AI, 17AII, 17AIII: Contact area directly in contact with the insulating part or solid electrolyte part, which are components of the non-connected portion of the positive terminal. 17BI, 17BII, 17BIII: Contact areas that directly contact the insulating part or solid electrolyte part, which is a component of the negative terminal and is not directly connected; 18I, 18II, 18III: Non-contact areas that do not directly contact the insulating part or solid electrolyte part, which is a component of the electrode terminal and is not directly connected; 18AI, 18AII, 18AIII: Non-contact areas that do not directly contact the insulating part or solid electrolyte part, which is a component of the positive terminal and is not directly connected; 18BI, 18BII, 18BIII: Contact areas that directly contact the insulating part or solid electrolyte part, which is a component of the positive terminal and is not directly connected; Non-contact areas where the insulating part or solid electrolyte part of the non-connected part of the negative terminal does not directly contact; 20I, 20II, 20III, 20': solid electrolyte layer; 30': side of electrode layer; 40': crack; 50I, 50II, 50III: insulating part or solid electrolyte part; 100I, 100II, 100III, 100': battery building unit; 200A': positive terminal; 200B': negative terminal; 300I, 300II, 300III: outer packaging; 500I, 500II, 500III, 500': solid battery.

Claims

1. A solid-state battery, The battery has at least one battery unit along the stacking direction. The battery unit includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer. The positive electrode layer and the negative electrode layer each include at least an active material layer and have a side portion, which is formed by a terminal connection portion and a terminal non-connection portion. Viewed from above, at least a portion of the non-connected terminal portion of at least one of the positive electrode layer and the negative electrode layer is surrounded by an insulating portion or a solid electrolyte portion. The non-connected terminal portion has a contact area that directly contacts the insulating portion or the solid electrolyte portion and a non-contact area that does not directly contact the insulating portion or the solid electrolyte portion. The area of ​​the non-contact region that is not in direct contact with the insulating part or the solid electrolyte part is 0.05 or more and 0.3 or less relative to the total area of ​​the non-connected portion of the terminal.

2. The solid-state battery according to claim 1, wherein, When viewed from above, the non-connected portion of the terminal is partially surrounded by the insulating portion or the solid electrolyte portion.

3. The solid-state battery according to claim 1, wherein, When viewed from above, at least two of the insulating portions or the solid electrolyte portions, which are separated from each other, surround the non-connected portion of the terminal.

4. The solid-state battery according to claim 1, wherein, When viewed from above, the insulating portion or solid electrolyte portion surrounding the non-connected portion of the terminal is discontinuous.

5. The solid-state battery according to claim 1, wherein, The non-contact area is disposed between one adjacent contact area and another contact area.

6. The solid-state battery according to claim 1, wherein, At least two of the non-contact areas are separated by a predetermined interval and configured separately.

7. The solid-state battery according to claim 6, wherein, The at least two non-contact areas, separated by the prescribed interval, are regularly arranged.

8. The solid-state battery according to claim 1, wherein, When viewed from above, the at least two non-contact areas are arranged opposite each other.

9. The solid-state battery according to claim 1, wherein, The contact area and the non-contact area are arranged alternately.

10. The solid-state battery according to claim 1, wherein, When viewed from above, the non-contact area is located at the corner of the electrode layer.

11. The solid-state battery according to any one of claims 1 to 10, wherein, The positive electrode layer and the negative electrode layer are layers capable of inserting and de-intercalating lithium ions.

Images