Solid-state battery

Abstract

The present application provides a kind of solid battery, even in the case of mixing installation with extremely small component, short circuit can be prevented to occur and carry out high-density installation.The solid battery of the present application has: battery main body, including the positive electrode layer and negative electrode layer stacked across solid electrolyte layer, and with the first end face and the second end face of opposing, and the peripheral surface between the first end face and the second end face;First external electrode, set to the first end face;Second external electrode, set to the second end face;And protective layer, cover the peripheral surface of battery main body, the solid battery has in the stacking direction of positive electrode layer and negative electrode layer relative first main surface and second main surface.First external electrode covers the first end face, while covering the first end face side of the peripheral surface of battery main body through protective layer, second external electrode covers the second end face, while covering the second end face side of the peripheral surface of battery main body through protective layer.A pair of first protrusions and second protrusions are provided on the first main surface and the second main surface, the pair of first protrusions and second protrusions extend from the first external electrode to the second external electrode along the long side direction connecting the first external electrode and the second external electrode, and are located at the two end portions in the short side direction.

Description

Technical Field

[0001] This invention relates to a solid-state battery. More specifically, this invention relates to a stacked solid-state battery in which the constituent layers of the battery structural unit are stacked together. 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 secondary batteries, 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 to replace liquid electrolytes, are under development.

[0004] However, when small solid-state batteries are housed in the battery compartment of small electronic devices such as mobile devices and are mounted with dust inside, current leakage may occur between the terminals of different batteries. To address this, for example, a solution has been proposed that the thickness of the central portion of the solid-state battery is thinner than the thickness of its ends (e.g., Patent Document 1).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2016-1601 Summary of the Invention

[0008] The technical problem that the invention aims to solve

[0009] In recent years, with the miniaturization of components mounted on substrates, the thickness of masks used for solder printing has decreased. This is because a larger amount of solder printing increases the likelihood of short circuits between terminals and between adjacent components. On the other hand, in the case of mountable solid-state batteries, a certain size of the solid-state battery is required to ensure a certain level of battery capacity. Therefore, the mountable solid-state battery is more likely to become the largest component among the mounting parts of the substrate. Consequently, when mounting a solid-state battery with a shape like that in Patent Document 1 on a substrate, a large amount of solder printing is required, thus creating a problem of short circuits with other, extremely small mounting parts.

[0010] Figure 12This is a schematic cross-sectional view used to illustrate the situation, showing an example of a solid-state battery 100 and a tiny mounting component 200 mounted on a substrate 90. The solid-state battery 100 has a storage body having a positive electrode layer 101 and a negative electrode layer 102 stacked between a solid electrolyte layer 103. The positive electrode layer 101 is composed of a positive current collector layer 104 and a positive active material layer 105, and the negative electrode layer 102 is composed of a negative current collector layer 106 and a negative active material layer 107. The storage body is covered by a protective layer 115. The positive current collector layer 104 and the negative current collector layer 106 are respectively connected to terminal electrodes 116. When the mounting component 200 is mounted on the substrate 90, since the mounting component 200 is a tiny component, the thickness of the solder layer 96 used to ensure electrical connection with the wiring electrodes 93, 94 can be reduced. In contrast, in the case of solid-state battery 100, in order to ensure the electrical connection between wiring electrodes 91, 92 and terminal electrode 116, the thickness of solder layer 95 needs to be increased. This results in an increased amount of solder printing, which increases the possibility of short circuits between the solder and adjacent mounting components.

[0011] Therefore, the object of the present invention is to provide a solid-state battery that can be installed at high density without the occurrence of short circuits, even when the solid-state battery is mixed with extremely small components.

[0012] Technical solutions for solving technical problems

[0013] To solve the above-mentioned technical problems, a solid-state battery according to one aspect of the present invention comprises:

[0014] The battery body includes a positive electrode layer and a negative electrode layer stacked with a solid electrolyte layer in between, and has a first end face and a second end face opposite to each other, and a peripheral surface disposed between the first end face and the second end face;

[0015] A first external electrode is disposed on the first end face;

[0016] A second external electrode is disposed on the second end face; and

[0017] A protective layer covering the peripheral surface of the battery body.

[0018] The solid-state battery has a first principal surface and a second principal surface opposite to each other in the stacking direction of the positive electrode layer and the negative electrode layer, characterized in that...

[0019] The first external electrode covers the first end face and, simultaneously, covers one side of the first end face of the peripheral surface of the battery body through the protective layer.

[0020] The second external electrode covers the second end face and, simultaneously, covers one side of the second end face of the peripheral surface of the battery body through the protective layer.

[0021] A pair of first protrusions and a pair of second protrusions are provided on the first main surface and the second main surface. The pair of first protrusions and second protrusions extend from the first external electrode to the second external electrode along the long side direction connecting the first external electrode and the second external electrode, and are located at both ends in the short side direction.

[0022] Furthermore, another aspect of the electronic device according to the present invention comprises an elongated substrate and a solid-state battery according to one embodiment mounted on the substrate, characterized in that...

[0023] The long side of the substrate is aligned with the long side of the first and second external electrodes of the solid-state battery.

[0024] The effects of the invention

[0025] According to the present invention, a solid-state battery can be provided that can be installed at high density without the occurrence of short circuits, even when the solid-state battery is installed together with extremely small components. Attached Figure Description

[0026] Figure 1 This is a schematic top view illustrating an example of the structure of a solid-state battery according to Embodiment 1 of the present invention.

[0027] Figure 2 This is a schematic perspective view showing an example of the structure of a solid-state battery according to Embodiment 1 of the present invention.

[0028] Figure 3 It is along Figure 1 A schematic longitudinal section of line III-III'.

[0029] Figure 4 It is along Figure 1 A schematic longitudinal section of line IV-IV'.

[0030] Figure 5 This is a schematic diagram illustrating the effect of the solid-state battery according to Embodiment 1 of the present invention.

[0031] Figure 6 This is a schematic diagram illustrating the effect of the solid-state battery according to Embodiment 1 of the present invention.

[0032] Figure 7 This is a schematic diagram illustrating the effect of the solid-state battery according to Embodiment 1 of the present invention.

[0033] Figure 8This is a schematic top view illustrating an example of the structure of the solid-state battery according to Embodiment 2 of the present invention.

[0034] Figure 9 This is a schematic perspective view showing another example of a solid-state battery according to Embodiment 1 of the present invention.

[0035] Figure 10 This is a schematic perspective view showing another example of a solid-state battery according to Embodiment 1 of the present invention.

[0036] Figure 11 This is a schematic perspective view showing another example of a solid-state battery according to Embodiment 1 of the present invention.

[0037] Figure 12 This is a schematic cross-sectional view representing an example of an existing solid-state battery. Detailed Implementation

[0038] The "solid-state battery" of the present invention will now be described in detail. Although the description is based on the accompanying drawings as needed, the illustrations are merely schematic and exemplary for the purpose of understanding the invention, and the appearance and size ratios may differ from the actual product.

[0039] In this specification, the term "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 (particularly preferably all battery constituent elements) are made of solids. Alternatively, in a preferred embodiment, the solid-state battery of this invention is a stacked solid-state battery configured as layers forming battery structural units, preferably with such layers being sintered bodies. It should be noted that "solid-state battery" includes not only so-called "secondary batteries" capable of repeated charging and discharging, but also "primary batteries" capable only of discharging. In a preferred embodiment of this 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," etc.

[0040] In this specification, "planar observation" refers to the shape of the object viewed from above or below, based on the thickness direction along the stacking direction of the layers constituting the solid-state battery. Furthermore, "cross-sectional observation" refers to the shape viewed from a direction substantially perpendicular to the thickness direction relative to the stacking direction of the layers constituting the solid-state battery (in short, the shape when cut from a plane parallel to the thickness direction). Additionally, "long side direction" refers to the direction along the long side when viewing the solid-state battery in a planar manner, and "short side direction" refers to the direction along the short side when viewing the solid-state battery in a planar manner. It should be noted that in the accompanying drawings (… Figures 2-4In sections 8 to 11), for convenience, the stacking direction (height direction) of the solid-state battery is designated as T, the long side direction (length direction) of the solid-state battery is designated as L, and the short side direction (width direction) of the solid-state battery is designated as W. Furthermore, "short side direction cross-section view" as used in this specification refers to the cross-section when cut along the short side direction, and "long side direction cross-section view" refers to the cross-section when cut along the long side direction. Additionally, the terms "up-down direction" and "left-right direction" used directly or indirectly in this specification correspond to the up-down direction and left-right direction in the figures, respectively. Unless otherwise stated, the same reference numerals or symbols denote the same parts or locations or have the same meaning. In a preferred embodiment, it can be understood that the vertical direction downwards (i.e., the direction of gravity) corresponds to the "downward direction," and its opposite direction corresponds to the "upward direction."

[0041] Implementation Method 1

[0042] The solid-state battery according to this embodiment is characterized by comprising: a battery body including a positive electrode layer and a negative electrode layer stacked with a solid electrolyte layer between them, and having a first end face and a second end face facing each other, and a peripheral surface disposed between the first end face and the second end face; a first external electrode disposed on the first end face; a second external electrode disposed on the second end face; and a protective layer covering the peripheral surface of the battery body. The solid-state battery has a first main face and a second main face facing each other in the stacking direction of the positive electrode layer and the negative electrode layer. The first external electrode covers the first end face and covers the first end face side of the peripheral surface of the battery body with the protective layer in between. The second external electrode covers the second end face and covers the second end face side of the peripheral surface of the battery body with the protective layer in between. A pair of first protrusions and a second protrusion are provided on the first main face and the second main face. The pair of first protrusions and the second protrusions extend from the first external electrode to the second external electrode along the long side direction connecting the first external electrode and the second external electrode, and are located at both ends in the short side direction.

[0043] Figure 1 This is a schematic top view showing an example of the structure of the solid-state battery 1 according to this embodiment. Figure 2 This is a schematic 3D diagram of solid-state battery 1. Figure 3 It is along Figure 1 A schematic longitudinal section view of line III-III'. Figure 4 It is along Figure 1 A schematic longitudinal section of line IV-IV'.

[0044] like Figure 1As shown, the solid-state battery 1 includes: a battery body 2 having a first end face 2a and a second end face 2b facing each other, and a peripheral surface 2c disposed between the first end face 2a and the second end face 2b; a first external electrode 4 disposed on the first end face 2a; a second external electrode 5 disposed on the second end face 2b; and a protective layer 3 covering the peripheral surface 2c of the battery body 2.

[0045] The battery body 2 has a laminated structure, forming a generally rectangular parallelepiped shape. The laminated structure includes at least one battery structural unit along the lamination direction. This battery structural unit comprises a positive electrode layer 21, a negative electrode layer 22, and a solid electrolyte layer 23 interposed therebetween. The battery body 2 has opposing first end faces 2a and 2b, and a peripheral surface 2c disposed between the first end faces 2a and 2b. It should be noted that the peripheral surface 2c has a first side face, a second side face, a third side face, and a fourth side face (none shown). The first and second side faces are aligned in the lamination direction of the positive and negative electrode layers (e.g., ...). Figure 2 Located in relative positions in the T direction, the third and fourth sides, for example, are in Figure 2 They are located at opposite positions in the W direction. For example... Figure 4 As shown, the end face of the positive electrode layer 21 is exposed on the first end face 2a, and the end face of the negative electrode layer 22 is exposed on the second end face 2b. Furthermore, the peripheral surface 2c of the battery body 2 is covered by a protective layer 3. It should be noted that the corners and edges of the battery body 2 can also be chamfered.

[0046] The solid-state battery 1 has a first main surface 1a and a second main surface 1b facing each other in the stacking direction of the positive electrode layer and the negative electrode layer, and a first side surface 1c and a second side surface 1d facing each other in the width direction of the solid-state battery 1. On the first main surface 1a and the second main surface 1b, a pair of first protrusions 11a and a second protrusion 11b are respectively provided, extending from the first external electrode 4 to the second external electrode 5 along the long side direction connecting the first external electrode 4 and the second external electrode 5, and located at both ends in the short side direction. The first protrusion 11a includes a protrusion 31a formed on the protective layer 3, and a protrusion 4a of the first external electrode 4 and a protrusion 5a of the second external electrode 5 located at both ends in the long side direction of the protrusion 31a. Similarly, the second protrusion 11b includes a protrusion 31b formed on the protective layer 3, and a protrusion 4b of the first external electrode 4 and a protrusion 5b of the second external electrode 5 located at both ends in the long side direction of the protrusion 31b.

[0047] The protrusions 31a and 31b formed in the protective layer 3 are provided at the edge along the long side of the solid battery 1 and protrude from the first main surface 1a or the second main surface 1b. In addition, the protrusions 4a and 4b of the first external electrode 4 and the protrusions 5a and 5b of the second external electrode 5 are provided at the apex of the solid battery 1 and protrude from the first main surface 1a or the second main surface 1b.

[0048] Here, the shape of the protrusion is not particularly limited; when viewed in cross-section along the short side, it can be rectangular, arc-shaped, curved, triangular, etc. Furthermore, as described later, in the short side direction, one or more intermediate protrusions can be provided between a pair of first protrusions 11a and second protrusions 11b located at both ends in the short side direction. It should be noted that in the figure, T represents the height direction of the solid-state battery A, L represents the length direction of the solid-state battery A, and W represents the width direction of the solid-state battery A. In this embodiment, the long side direction connecting the first external electrode 4 and the second external electrode 5 corresponds to the length direction of the solid-state battery A, the short side direction corresponds to the width direction of the solid-state battery A, and the stacking direction of the positive electrode layer and the negative electrode layer corresponds to the height direction.

[0049] The first external electrode 4 covers the first end face 2a of the battery body 2, and simultaneously covers the first end face 2a side of the peripheral surface 2c of the battery body 2 through the protective layer 3, and is electrically connected to the positive electrode layer 21. For example, as Figure 4 As shown, the first external electrode 4 is configured to cover the entire circumference of the first end face 2a side of the peripheral surface 2c of the battery body 2, separated by the protective layer 3, i.e., in a U-shaped cross-section. Furthermore, the second external electrode 5 covers the second end face 2b of the battery body 2, and simultaneously covers the second end face 2b side of the peripheral surface 2c of the battery body 2, separated by the protective layer 3, and is electrically connected to the negative electrode layer 22. For example, as... Figure 4 As shown, the second external electrode 5 can be arranged in a manner that covers the entire circumference of the second end face 2b side of the peripheral surface 2c of the battery body 2 through the protective layer 3, that is, the cross-section is U-shaped.

[0050] The effects of the present invention will be described below. Figure 5 This is a schematic perspective view showing the solid-state battery 1 mounted on a substrate 70. Solder is printed on pads 71 ​​and 72 of the substrate 70, and the solid-state battery 1 is mounted thereon. In this invention, since the first external electrode 4 and the second external electrode 5 of the solid-state battery 1 can directly contact the pads 71 ​​and 72, the amount of solder printed to ensure electrical connection between the pads 71 ​​and 72 and the first and second external electrodes 4 and 5 can be reduced. This reduces the possibility of short circuits between adjacent mounted components, enabling high-density mounting. It should be noted that reducing the amount of solder printed may reduce self-alignment, but in this invention, the surface area of ​​the first and second external electrodes can be increased without increasing the width of the solid-state battery 1. This increases the surface tension of the molten solder, thus suppressing the reduction in self-alignment. It should be noted that self-alignment refers to the adjustment of the mounted component's position using the surface tension of the molten solder.

[0051] in addition, Figure 6 This is another schematic perspective view showing the solid-state battery 1 mounted on the substrate 70. Even if the substrate is bent by an external force, resulting in warping in the bending direction, the solid-state battery 1 has a first protrusion and a second protrusion at both ends in the width direction of the first and second main surfaces. Therefore, the solid-state battery 1 can be supported by these four protrusions, which can suppress the formation of cracks and improve the mechanical strength of the solid-state battery 1.

[0052] in addition, Figure 7 This is another schematic perspective view showing the solid-state battery 1 mounted on the substrate 70. When mounting using a mounting tool, as indicated by the arrows, stress tends to concentrate at specific locations, sometimes causing cracks in the solid-state battery 1. Even in such cases, the support of these four protrusions helps to suppress cracking of the solid-state battery 1, thus improving its mechanical strength. In particular, the cross-sectional shape of the protrusions, by using curved protrusions, easily mitigates stress concentration. As used in this specification, "curved" refers to a shape that bulges in the lamination direction relative to the first main surface 1a or the second main surface 1b and has rounded corners. Such a shape easily and appropriately mitigates stress concentration.

[0053] Furthermore, as will be discussed later, from the perspective of solid-state battery manufacturing (the perspective of impregnation with a protective layer paste), the first side 3c and the second side 3d opposite each other in the short side direction (W direction) of the solid-state battery can be curved surfaces (see reference). Figure 3 The term "curved surface" as used in this specification refers to a shape that is not perpendicular (90°) to the first main surface 1a or the second main surface 1b, but has rounded corners. When set to such a shape, even... Figure 7 When stress is concentrated at a specific location as indicated by the middle arrow, the first and second sides are curved surfaces, which can easily and appropriately mitigate the stress concentration.

[0054] Furthermore, the degree of curvature of protrusions 11a and 11b can be made different from that of protrusion 11b. This way, if the solid-state battery is asymmetrical, its left and right orientation can be determined during installation, preventing it from being installed in the wrong direction.

[0055] The materials used in the solid-state battery of the present invention will be described below.

[0056] When the various layers constituting a solid battery are formed by firing, the positive electrode layer, negative electrode layer, and solid electrolyte layer of the solid battery can form a firing layer. Preferably, the positive electrode layer, negative electrode layer, and solid electrolyte layer are fired together as a single unit, so the solid battery stack can form a single fired body.

[0057] (Positive electrode layer and negative electrode layer)

[0058] The positive electrode layer is an electrode layer containing at least a positive electrode active material. The positive electrode layer may also contain a solid electrolyte. For example, the positive electrode layer may be composed of a sintered body containing at least positive electrode active material particles and solid electrolyte particles. In a preferred embodiment, the positive electrode layer may be composed of a sintered body substantially containing only positive electrode active material particles and solid electrolyte particles. On the other hand, the negative electrode layer is an electrode layer containing at least a negative electrode active material. The negative electrode layer may also contain a solid electrolyte. For example, the negative electrode layer may be composed of a sintered body containing at least negative electrode active material particles and solid electrolyte particles. In a preferred embodiment, the negative electrode layer may be composed of a sintered body substantially containing only negative electrode active material particles and solid electrolyte particles.

[0059] Positive and negative electrode active materials are substances that participate in electron transfer in a solid-state battery. Ions move (conduct) between the positive and negative electrode layers via the solid electrolyte, thus transferring electrons and enabling charging and discharging. The positive and negative electrode layers are preferably layers capable of intercalating and deintercalating sodium ions or lithium ions (more preferably lithium ions). That is, the solid-state battery is preferably an all-solid-state secondary battery in which sodium ions or lithium ions move between the positive and negative electrode layers via the solid electrolyte for charging and discharging.

[0060] (Positive electrode active material)

[0061] Examples of positive electrode active materials capable of lithium ion intercalation / deintercalation 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 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.

[0062] Furthermore, 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. For example, in the case of sodium phosphate compounds, at least one can be selected from the group consisting of Na3V2(PO4)3, NaCoFe2(PO4)3, Na2Ni2Fe(PO4)3, Na3Fe2(PO4)3, Na2FeP2O7, Na4Fe3(PO4)2(P2O7), and NaFeO2 as a sodium-containing layered oxide.

[0063] Furthermore, the positive electrode active material can be, for example, an oxide, a disulfide, a chalcogenide, or a conductive polymer. Oxides can be, for example, titanium oxide, vanadium oxide, or manganese dioxide. Disulfides can be, for example, titanium disulfide or molybdenum sulfide. Chalcogenides can be, for example, niobium selenide. Conductive polymers can be, for example, disulfides, polypyrrole, polyaniline, polythiophene, poly(p-styrene), polyacetylene, or poly(phenylene oxide).

[0064] (Negative electrode active material)

[0065] Examples of negative electrode active materials capable of intercalating and deintercalating lithium ions 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), carbon materials such as graphite, 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. Examples of lithium alloys include Li-Al. Examples of lithium phosphate compounds with a NASICON-type structure include Li3V2(PO4)3 and / or LiTi2(PO4)3. Examples of lithium phosphate compounds with an olivine-type structure include Li3Fe2(PO4)3 and / or LiCuPO4. Examples of lithium oxides with a spinel-type structure include Li4Ti5O. 12 wait.

[0066] 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.

[0067] The positive and / or negative electrode layers may also contain conductive materials. Examples of conductive materials contained in the positive and negative electrode layers include at least one material composed of metals such as silver, palladium, gold, platinum, aluminum, copper, and nickel, as well as carbon.

[0068] Furthermore, the positive and / or negative electrode layers may also contain conductive materials. Examples of conductive materials 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.

[0069] 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.

[0070] (Solid electrolyte layer)

[0071] Solid electrolytes are substances capable of conducting sodium or lithium ions. Specifically, in solid-state batteries, the solid electrolyte layer, forming the battery structural unit, creates a layer between the positive and negative electrode layers capable of conducting sodium or lithium ions. It should be noted that the solid electrolyte only needs to be disposed at least between the positive and negative electrode layers. That is, the solid electrolyte can also exist around the positive and / or negative electrode layers, extending outwards from between them. Examples of solid electrolytes capable of conducting lithium ions include lithium-containing polyanionic compounds with a NASICON structure, oxides with a perovskite structure, oxides with garnet-type or garnet-like structures, and oxide glass-ceramic lithium-ion conductors. Examples of lithium-containing polyanionic compounds with a NASICON structure include lithium phosphate compounds such as 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. 12Examples of suitable lithium-ion conductors in oxide glass-ceramic systems include, for instance, phosphoric acid compounds containing lithium, aluminum, and titanium as constituent elements (LATP) and phosphoric acid compounds containing lithium, aluminum, and germanium as constituent elements (LAGP). Furthermore, examples of solid electrolytes capable of conducting sodium ions include sodium-containing phosphoric acid compounds with a NASICON structure, oxides with a perovskite structure, and oxides with garnet-type or garnet-like structures. Examples of sodium-containing phosphoric acid compounds with a NASICON structure include Na... x M y (PO4)3 (1≤x≤4, 1≤y≤2, M is selected from at least one of the group consisting of Zr, Ti, Ge, Al, Ga and Fe, etc., and a portion of P can be replaced by Si, S, etc.).

[0072] Solid electrolytes may contain conductive materials. The conductive materials contained in solid electrolytes may be selected from, for example, the same conductive materials that may be contained in the positive electrode layer and / or the negative electrode layer.

[0073] 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.

[0074] (protective layer)

[0075] A protective layer is typically formed on the outermost side of a solid-state battery for electrical, physical, and / or chemical protection. The protective layer contains ceramic powder and an inorganic binder. The ceramic contains at least one of a metal oxide, a metal nitride, and a metal carbide. Here, "metal" is defined as containing a half-metal. For example, the ceramic contains at least one of Al₂O₃ (alumina: bauxite), SiO₂ (silicon oxide: quartz), SiN (silicon nitride), AlN (aluminum nitride), and SiC (silicon carbide). The inorganic binder preferably contains a lithium phosphate compound. The lithium phosphate compound is preferably sintered. The lithium phosphate compound is preferably the same as that contained in the solid electrolyte layer. Furthermore, the composition or structure of the lithium phosphate compound contained in the outer packaging material and the solid electrolyte layer may be the same or different.

[0076] Furthermore, the protective layer is preferably integrally fired with the peripheral surface of the battery body. Here, the peripheral surface of the battery body with the protective layer integrally fired refers to the uppermost and lowermost layers of the battery body, as well as the side surfaces other than the first and second end faces where the first and second external electrodes are formed. The uppermost and lowermost layers of the battery body can be positive electrode layers or negative electrode layers, or a connecting layer bonded to the protective layer can be provided. By bonding the connecting layer to the protective layer, the integration of the battery body and the protective layer becomes easier. The connecting layer preferably uses a solid electrolyte layer containing a polyanionic compound. Here, as a solid electrolyte containing a polyanionic compound, examples include lithium phosphate compounds as lithium-ion conductors and sodium phosphate compounds as sodium-ion conductors.

[0077] Furthermore, from the perspective of integrated firing, the positive electrode layer, negative electrode layer, and solid electrolyte layer constituting the main body of the battery can contain at least one common element. Examples of this include the addition of Al₂O₃, SiO₂, MgO, etc., to the positive electrode layer in addition to the positive electrode active material and solid electrolyte; similarly, examples of the addition of Al₂O₃, SiO₂, MgO, etc., to the negative electrode layer in addition to the negative electrode active material and solid electrolyte; and examples of the addition of Al₂O₃, SiO₂, MgO, etc., to the solid electrolyte layer in addition to the solid electrolyte.

[0078] Furthermore, from the viewpoint of ensuring water vapor barrier properties and mechanical strength, the average thickness of the protective layer is 500 μm or less and 1 μm or more, preferably 100 μm or less and 5 μm or more. Here, the average thickness of the protective layer is calculated using the average thickness of 100 portions of the upper surface portion, lower surface portion, and side portion of the protective layer.

[0079] (External electrode)

[0080] Solid-state batteries generally have terminals (external electrodes). Specifically, a positive terminal (corresponding to a first external electrode) and a negative terminal (corresponding to a second external electrode) are provided on a first end face and a second end face located on opposite sides of the battery body. More specifically, a positive terminal connected to a positive electrode layer and a negative terminal connected to a negative electrode layer are provided. Such terminals are preferably made of materials with high conductivity. There are no particular limitations on the material of the external electrodes, and at least one material selected from the group consisting of silver, gold, platinum, aluminum, copper, tin, and nickel can be included.

[0081] [Solid-state battery manufacturing method]

[0082] The following describes the manufacturing method of the solid-state battery according to Embodiment 1 of the present invention.

[0083] The solid-state battery described in Embodiment 1 can be manufactured using a combination of green sheet processing, screen printing, and impregnation methods. In one embodiment, a solid electrolyte layer is formed by green sheet processing, a positive electrode layer and a negative electrode layer are formed by screen printing, and a protective layer is applied to the periphery of the stacked body by impregnation, thereby enabling the manufacture of a solid-state battery. It should be noted that the following description is based on this embodiment, but is not limited to it; a predetermined stacked body can also be formed using green sheet processing or screen printing.

[0084] (The process of forming unfired laminates)

[0085] First, a paste for a solid electrolyte layer is coated onto a substrate (e.g., a PET film). Additionally, pastes for a positive electrode layer, a negative electrode layer, an electrode separation section, and an outer packaging material are prepared.

[0086] Each paste can be prepared by wet mixing a specified 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 conductive material, with an organic carrier formed by dissolving an organic material in a solvent. The paste for the positive electrode layer contains a positive electrode active material, a conductive material, a solid electrolyte material, an organic material, and a solvent. The paste for the negative electrode layer contains a negative electrode active material, a conductive material, a solid electrolyte material, an organic material, and a solvent. The paste for the solid electrolyte layer contains a solid electrolyte material, a conductive material, an organic material, and a solvent. The paste for the electrode separation section contains an insulating material (e.g., a solid electrolyte material), a conductive material, an organic material, and a solvent. The paste for the protective layer contains a vitreous material, a crystalline material, an organic material, and a solvent.

[0087] 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.

[0088] The supporting substrate is not particularly limited as long as it can support the unfired laminate; for example, a substrate made of a polymer such as polyethylene terephthalate can be used. When the unfired laminate is held on the substrate for the firing process, a substrate that exhibits heat resistance to the firing temperature can be used.

[0089] As a solid electrolyte material contained in a paste for a solid electrolyte layer, powders composed of lithium phosphate compounds having a NASICON structure, oxides having a perovskite structure, and / or oxides having a garnet-type or garnet-like structure, as described above, can be used.

[0090] As a positive electrode active material contained in the paste for the positive electrode layer, at least one of the following can be used: lithium phosphate compound having a NASICON-type structure, lithium phosphate compound having an olivine-type structure, lithium layered oxide, and lithium oxide having a spinel-type structure.

[0091] As a negative electrode active material contained in the negative electrode layer paste, for example, a negative electrode active material containing 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), 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, as well as materials contained in the above-mentioned solid electrolyte paste and conductive materials, etc.

[0092] 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 above-mentioned organic material; for example, toluene and / or ethanol can be used.

[0093] As a conductive material, at least one selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, boron oxide, silicon oxide, bismuth oxide, and phosphorus oxide can be used.

[0094] A solid electrolyte layer sheet of a specified thickness is formed on a substrate (e.g., PET film) by drying a coated paste on a hot plate heated to above 30°C and below 50°C.

[0095] (Layering process of the battery body)

[0096] A solid electrolyte layer sheet is peeled off from a substrate. A positive electrode layer is formed on the solid electrolyte layer sheet by screen printing, and electrode separation portions are formed around the positive electrode layer by screen printing, thus fabricating a solid electrolyte layer sheet with an integrated positive electrode layer. Conversely, a negative electrode layer is formed on the solid electrolyte layer sheet by screen printing, and electrode separation portions are formed around the negative electrode layer by screen printing, thus fabricating a solid electrolyte layer sheet with an integrated negative electrode layer. These integrated solid electrolyte layer sheets with positive and negative electrodes are alternately stacked with solid electrolyte layers interspersed, resulting in a battery body with solid electrolyte layers as connecting layers at the top and bottom. Next, preferably, a hot-pressing process is performed at a specified pressure (e.g., approximately 50 MPa or more and approximately 100 MPa or less), followed by isotropic pressing at a specified pressure (e.g., approximately 150 MPa or more and approximately 300 MPa or less). This allows the fabrication of the specified battery body.

[0097] Next, a protective layer is formed by immersing the peripheral surface of the battery body in a protective layer paste. First, a protective layer is formed on the first and second sides by immersing the uppermost surface (corresponding to the first side) and the lowermost surface (corresponding to the second side) of the battery body in the protective layer paste. Next, a protective layer is formed on the third and fourth sides of the battery body, where the end faces of the positive and negative electrode layers are not exposed, by immersing them in the protective layer paste. At this time, the immersion in the protective layer paste is done in a manner that forms protrusions on the third and fourth sides. As a method for forming protrusions on the third and fourth sides, for example, a method of repeatedly immersing the third and fourth sides in the protective layer paste can be listed. Thus, by repeatedly immersing the third and fourth sides in the protective layer paste, such as... Figure 3 As shown, the first and second sides are curved surfaces. It should be noted that a method using a high-viscosity protective layer paste can be used instead of multiple impregnations. Alternatively, screen printing can be used. For example, a protective layer sheet is manufactured using the same method described in the preceding paragraphs, and the portion forming the protrusions is coated with a protective layer paste via screen printing to form protrusions. Then, the battery body is sandwiched between the protective layer sheets with the protrusions formed on the top and bottom layers for lamination.

[0098] (Firing process)

[0099] In the firing process, the unfired laminate is fired. Although this is only an example, firing is carried out by removing organic materials in a nitrogen atmosphere containing oxygen or in the atmosphere, for example at 500°C, followed by heating in a nitrogen atmosphere or in the atmosphere, for example at a temperature above 550°C and below 1000°C. Firing can be performed simultaneously with pressurization of the unfired laminate in the lamination direction (depending on the case, the lamination direction and a direction perpendicular to that lamination direction). It should be noted that firing can be performed once after a protective layer is applied to the battery body (simultaneous firing), or the protective layer can be applied after firing the battery body and then fired (sequential firing).

[0100] Next, external electrodes are added to the resulting laminate. A first external electrode is configured to be electrically connected to the positive electrode layer, and a second external electrode is configured to be electrically connected to the negative electrode layer. Here, the first external electrode is configured to cover the first end face of the battery body, and simultaneously cover the first end face side of the peripheral surface of the battery body through a protective layer. This results in a first external electrode with protrusions at all four corners. Similarly, the second external electrode is configured to cover the second end face of the battery body, and simultaneously cover the second end face side of the peripheral surface of the battery body through a protective layer. This results in a second external electrode with protrusions at all four corners. For example, it is preferable to form the external electrodes by impregnation in a metal paste or the like. The number of impregnations is not particularly limited, but two or more impregnations are preferred. Furthermore, although not particularly limited, the external electrodes are preferably made of at least one material selected from silver, gold, platinum, aluminum, copper, tin, and nickel.

[0101] It should be noted that the above manufacturing method describes the case where the solid battery is a lithium-ion secondary battery. However, by using a negative electrode active material and a positive electrode active material that can intercalate and deintercalate sodium ions, and a solid electrolyte that can conduct sodium ions, a solid battery that is a sodium-ion secondary battery can also be manufactured.

[0102] (Implementation Method 2)

[0103] This embodiment relates to an electronic device, characterized in that the electronic device comprises an elongated substrate and a solid-state battery according to Embodiment 1 mounted on the substrate, wherein the long side direction of the substrate is consistent with the long side direction of the first external electrode and the second external electrode connected to the solid-state battery.

[0104] Figure 8 This is a schematic top view illustrating an example of the structure of the electronic device according to this embodiment. A solid-state battery 1 is mounted on a long, narrow substrate 70. In this embodiment, the long side direction of the first external electrode 4 and the second external electrode 5 connecting the solid-state battery 1 is aligned with the long side direction of the long, narrow substrate 70. Generally, in the case of a long, narrow substrate 70, the long side direction is easily bent by external forces, leading to warping; conversely, the short side direction is less prone to bending. The solid-state battery 1 has a first protrusion and a second protrusion extending in the long side direction connecting the first external electrode 4 and the second external electrode 5 on opposing first and second main surfaces. Therefore, the support of these four protrusions helps to suppress cracking in the solid-state battery 1. This improves the mechanical strength of the solid-state battery 1.

[0105] The substrate can be any long strip shape; there are no particular limitations. For example, printed circuit boards (PCBs) can be used. PCBs are generally made of paper and glass cloth, which are less prone to bending in the fiber direction (corresponding to the long side direction) and less likely to warp. Therefore, by using a PCB, and aligning its fiber direction with the long side direction of the first and second external electrodes of the solid-state battery, cracking in the solid-state battery can be further suppressed.

[0106] Any electronic device that uses a solid-state battery is acceptable; there are no specific limitations. Examples include power devices, IoT devices, wearable devices, and real-time clocks (RTCs).

[0107] The embodiments of the present invention have been described above, but only typical examples have been exemplified. Therefore, the present invention is not limited thereto, and those skilled in the art will readily understand that various methods can be considered without changing the spirit of the present invention.

[0108] For example, in Embodiment 1, a solid battery 1 with a pair of first protrusions and a second protrusion located at both ends in the short side direction was described as a protrusion. However, in the short side direction, one or more intermediate protrusions may be provided between the pair of first protrusions and the second protrusions. In addition, regarding the shape of the protrusion, it may be rectangular, arc-shaped, curved, triangular, or other shapes when viewed in cross-section in the short side direction.

[0109] Figures 9-11 This is a schematic perspective view showing an example of a solid-state battery with one or more central protrusions. Figure 9 The solid-state battery 81 shown is an example in which an intermediate protrusion 12c is provided between a pair of first protrusions 12a and second protrusions 12b. The protrusion has a rectangular shape when viewed in cross-section along its short side. Here, the first protrusion 12a includes a protrusion 32a formed on the protective layer 32, and protrusions 41a of the first external electrode 41 and 51a of the second external electrode 51 located at both ends of the protrusion 32a along its long side. Similarly, the second protrusion 12b includes a protrusion 32b formed on the protective layer 32, and protrusions 41b of the first external electrode 41 and 51b of the second external electrode 51 located at both ends of the protrusion 32b along its long side. The intermediate protrusion 12c includes a protrusion 32c formed on the protective layer 32, and protrusions 41c of the first external electrode 41 and 51c of the second external electrode 51 located at both ends of the protrusion 32c along its long side.

[0110] in addition, Figure 10The solid-state battery 82 shown is an example in which an intermediate protrusion 13c is provided between a pair of first protrusions 13a and second protrusions 13b. The protrusion has a triangular shape when viewed from above in the short-side direction. Here, the first protrusion 13a includes a protrusion 33a formed on the protective layer 33, and protrusions 42a of the first external electrode 42 and 52a of the second external electrode 52 located at both ends of the protrusion 33a in the long-side direction. Similarly, the second protrusion 13b includes a protrusion 33b formed on the protective layer 33, and protrusions 42b of the first external electrode 42 and 52b of the second external electrode 52 located at both ends of the protrusion 33b in the long-side direction. The intermediate protrusion 13c includes a protrusion 33c formed on the protective layer 33, and protrusions 42c of the first external electrode 42 and 52c of the second external electrode 52 located at both ends of the protrusion 33c in the long-side direction.

[0111] in addition, Figure 11 The solid-state battery 83 shown is an example in which an intermediate protrusion 14c is provided between a pair of first protrusions 14a and second protrusions 14b. The protrusion has a curved shape when viewed in cross-section along its short side. Here, the first protrusion 14a includes a protrusion 34a formed on the protective layer 34, and protrusions 43a of the first external electrode 43 and 53a of the second external electrode 53 located at both ends of the protrusion 34a along its long side. Similarly, the second protrusion 14b includes a protrusion 34b formed on the protective layer 34, and protrusions 43b of the first external electrode 43 and 53b of the second external electrode 53 located at both ends of the protrusion 34b along its long side. The intermediate protrusion 14c includes a protrusion 34c formed on the protective layer 34, and protrusions 43c of the first external electrode 43 and 53c of the second external electrode 53 located at both ends of the protrusion 34c along its long side. It should be noted that... Figures 9-11 In the diagram, the number of convex parts in the middle is not limited to the number shown in the diagram; as long as it is 1 or more, it is acceptable.

[0112] Based on the above Figures 9-11 The solid-state battery shown, by providing one or more intermediate protrusions between a pair of first and second protrusions, increases the surface area of ​​the first and second external electrodes without increasing the width of the solid-state battery. This further improves mounting strength. Furthermore, the increased surface area of ​​the first and second external electrodes further increases the surface tension of the molten solder, further suppressing the reduction of self-alignment. Additionally, even if the substrate warps due to external force, the intermediate protrusion provides further support, further suppressing crack formation in the solid-state battery. This further improves the mechanical strength of the solid-state battery.

[0113] Industrial availability

[0114] The solid-state battery according to one embodiment of the present invention can be applied to various fields where batteries or energy storage are envisioned. Although only an example, the solid-state battery of the present invention can be applied to the following fields: electrical information and communication fields using mobile devices, etc. (e.g., electrical and electronic equipment fields including mobile phones, smartphones, laptops, digital cameras, activity meters, ARM computers, electronic paper, RFID tags, card-type electronic money, smartwatches, and other small electronic devices or mobile devices); household and small industrial applications (e.g., power tools, golf carts, home, care, and industrial robots); large industrial applications (e.g., forklifts, elevators, port cranes); transportation systems (e.g., hybrid vehicles, electric vehicles, buses, trams, electric-assisted bicycles, electric motorcycles, etc.); power systems (e.g., various power generation, load conditioners, smart grids, general household energy storage systems, etc.); medical applications (medical devices such as headphones and hearing aids); pharmaceutical applications (medical management systems, etc.); and IoT fields; space and deep-sea applications (e.g., space probes, underwater research vessels, etc.), etc.

[0115] Explanation of reference numerals in the attached figures

[0116] 1: Solid-state battery; 1a: First main surface; 1b: Second main surface; 1c: First side surface; 1d: Second side surface; 11a, 12a, 13a, 14a: First protrusions; 11b, 12b, 13b, 14b: Second protrusions; 12c, 13c, 14c: Middle protrusions; 2: Battery body; 2a: First end face; 2b: Second end face; 2c: Peripheral surface; 3, 32, 33, 34: Protective layers; 31a, 32a, 33a, 34a: Protrusions of the protective layer; 3 1b, 32b, 33b, 34b: Protrusions of the protective layer; 32c, 33c, 34c: Protrusions of the protective layer; 4, 41, 42, 43: First external electrode; 4a, 41a, 42a, 43a: Protrusions of the first external electrode; 5, 51, 52, 53: Second external electrode; 5a, 51a, 52a, 53a: Protrusions of the second external electrode; 21: Positive electrode layer; 22: Negative electrode layer; 23: Solid electrolyte layer; 70: Substrate; 71, 72: Pads.

Claims

1. An mounting-type solid-state battery, comprising: The battery body includes a positive electrode layer and a negative electrode layer stacked with a solid electrolyte layer in between, and has a first end face and a second end face opposite to each other, and a peripheral surface disposed between the first end face and the second end face; A first external electrode is disposed on the first end face; A second external electrode is disposed on the second end face; and The protective layer covers only the peripheral surface of the battery body. The mounted solid-state battery has a first main surface and a second main surface opposite to each other in the stacking direction of the positive electrode layer and the negative electrode layer, wherein... The first external electrode covers the first end face and, simultaneously, covers one side of the first end face of the peripheral surface of the battery body through the protective layer. The second external electrode covers the second end face and, simultaneously, covers one side of the second end face of the peripheral surface of the battery body through the protective layer. A pair of first protrusions and a pair of second protrusions are provided on the first main surface and the second main surface. The pair of first protrusions and second protrusions extend continuously from the first external electrode to the second external electrode along the long side direction connecting the first external electrode and the second external electrode, and are located at both ends in the short side direction perpendicular to the long side direction.

2. The mounting-type solid-state battery according to claim 1, wherein, The mounting solid-state battery further includes one or more third protrusions extending along the long side direction between the first protrusion and the second protrusion on the first main surface and the second main surface.

3. The mounting-type solid-state battery according to claim 1, wherein, The first protrusion or the second protrusion includes a protrusion formed on the protective layer, a protrusion formed on the first external electrode, and a protrusion formed on the second external electrode.

4. The mounting-type solid-state battery according to any one of claims 1 to 3, wherein, The mounting solid-state battery has a first side and a second side opposite to each other in the short side direction, and the first protrusion and the second protrusion form a portion of the first side and the second side.

5. The mounting-type solid-state battery according to claim 4, wherein, The first side and the second side are curved surfaces.

6. The mounting-type solid-state battery according to any one of claims 1 to 3, wherein, The first protrusion and the second protrusion have a curved shape when viewed in cross-section along the short side.

7. The mounting-type solid-state battery according to claim 6, wherein, The degree of curvature of the first protrusion is different from that of the second protrusion.

8. An electronic device comprising an elongated substrate and a mounting-type solid-state battery according to any one of claims 1 to 7 mounted on said substrate, wherein, The long side of the substrate is aligned with the long side of the first and second external electrodes of the mounting solid-state battery.

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