Solid state battery

Abstract

Provided is a solid-state battery. This solid-state battery comprises a solid-state battery stacked body having at least one battery constituting unit which comprises a positive electrode layer, a negative electrode layer, and a solid electrolytic layer interposed between the positive electrode layer and the negative electrode layer, the solid-state battery having outer terminals respectively provided to side surfaces facing the solid-state battery stacked layer, and further having an exterior member which covers the solid-state battery stacked body, wherein voids are present inside the exterior member on the side adjacent to the solid-state battery stacked body.

Description

[Technical field]

[0001] The present invention relates to a solid-state battery, and more specifically, to a solid-state battery in which an exterior member is provided so as to cover a solid-state battery stack. [Background technology]

[0002] 2. Description of the Related Art Secondary batteries that can be repeatedly charged and discharged have been used for various purposes. For example, secondary batteries are used as power sources for electronic devices such as smartphones and laptop computers.

[0003] In secondary batteries, liquid electrolytes are generally used as a medium for ion migration that contributes to charging and discharging. In other words, so-called electrolytic solutions are used in secondary batteries. However, in such secondary batteries, safety is generally required in terms of preventing leakage of the electrolytic solution. In addition, organic solvents and the like used in the electrolytic solution are flammable substances, so safety is also required in that respect.

[0004] Therefore, research is being conducted on solid-state batteries that use solid electrolytes instead of liquid electrolytes. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-220106 A [Patent Document 2] JP 2015-220107 A Summary of the Invention [Problem to be solved by the invention]

[0006] The present inventors realized that conventional solid-state batteries have problems to be overcome and found it necessary to take measures to address these problems. Specifically, the present inventors found the following problems:

[0007] For example, as shown in FIG. 15, a conventional solid-state battery 100 includes at least one battery unit 105 including a positive electrode layer 101, a negative electrode layer 102, and a solid electrolyte layer 103 interposed therebetween, arranged along the stacking direction. Such a battery unit includes an inorganic layer such as a silicon oxynitride thin film formed by sputtering as a waterproof layer 110 having a thickness of about 5 to 1000 nm. The inventors of the present application have found that a waterproof layer 110 having such a thickness cannot withstand the stress generated by the volume expansion and contraction of the battery unit during charging and discharging of the solid-state battery, and may crack or chip. The inventors of the present application have also found that if cracks or chips occur in the waterproof layer 110 made of such an inorganic layer, moisture or water vapor will penetrate into the battery unit, causing a significant decrease in the performance of the solid-state battery. Furthermore, in a conventional solid-state battery 100, a resin layer 120 formed from silicone rubber, fluororesin or the like may be provided on the upper side of the waterproof layer 110. However, the inventors' research has revealed that such a resin layer 120 allows water vapor to pass through and enter the battery body, and that the gas barrier properties are insufficient.

[0008] The present invention has been made in view of the above problems. That is, a main object of the present invention is to provide a solid-state battery including an exterior member capable of suppressing the occurrence of cracks, chips, and the like and having improved gas barrier properties. [Means for solving the problem]

[0009] The inventors of the present application attempted to solve the above problems by taking a new approach, rather than simply extending the conventional technology, and as a result, they have invented a solid-state battery that achieves the above-mentioned main object.

[0010] The present invention provides a solid-state battery, which includes a solid-state battery stack including at least one battery unit, for example along a stacking direction, including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer, and further includes external terminals, specifically, a positive electrode terminal and a negative electrode terminal, provided on opposing side surfaces of the solid-state battery stack, and further includes an exterior member covering the solid-state battery stack, and a gap is present on the side of the exterior member adjacent to the solid-state battery stack (or the interface) inside the solid-state battery stack. Effect of the Invention

[0011] In the present invention, a solid-state battery can be obtained that is capable of suppressing or preventing the occurrence of cracks, chips, etc., and is equipped with an exterior member having improved gas barrier properties against water vapor, etc. Note that the effects described in this specification are merely examples and are not limiting, and additional effects may also be provided. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing a solid-state battery stack that can be used in a solid-state battery according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view that shows a schematic exterior member that can be used in the solid-state battery according to one embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing another exterior member that can be used in the solid-state battery according to one embodiment of the present invention. [Figure 4] FIG. 4 is a schematic cross-sectional view showing an exterior member that can be used in a solid-state battery according to another embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic cross-sectional view showing a schematic view of another exterior member that can be used in a solid-state battery according to another embodiment of the present invention. [Figure 6] FIG. 6 is a schematic cross-sectional view showing a solid-state battery according to one embodiment of the present invention. [Figure 7]FIG. 7 is a schematic cross-sectional view showing a solid-state battery according to another embodiment of the present invention. [Figure 8] FIG. 8 is a photograph partially exemplarily illustrating a cross section of a solid-state battery according to one embodiment of the present invention. [Figure 9] FIG. 9 is a schematic diagram showing the presence of voids in the exterior member. [Figure 10] FIG. 10 is a schematic diagram showing the formation of a cut surface in a cross-sectional observation of an exterior member. [Figure 11] FIG. 11 shows a sample scanning electron micrograph (SEM) showing a cross section of a solid-state battery (scale bar: 10 μm). [Figure 12] FIG. 12 shows the "exterior member (inside)" and the "exterior member (outside)" separately in a sample scanning electron microscope (SEM) photograph showing a cross section of a solid-state battery (scale bar: 10 μm). [Figure 13] FIG. 13 shows a state in which both the "exterior member (inside)" and the "exterior member (outside)" in a sample of an electron microscope (SEM) photograph showing a cross section of a solid-state battery have been binarized. [Figure 14] FIG. 14 shows (A) a sample scanning electron microscope (SEM) photograph showing a cross section of a solid-state battery, (B) the sample in a state where the boundary between the “exterior member (inside)” and the “battery body (solid-state battery laminate)” is clearly defined and binarized, and (C) the state where the “exterior member (outside)” is binarized together with the “exterior member (inside)” without clearly defining the boundary between the “exterior member (inside)” and the “battery body (solid-state battery laminate)”. [Figure 15] FIG. 15 is a schematic cross-sectional view illustrating a conventional solid-state battery. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the "solid-state battery" of the present invention (e.g., the solid-state battery shown more specifically in Fig. 6 and Fig. 7), and in particular the "exterior member" (e.g., the exterior member shown in Figs. 2 to 5) that covers the solid-state battery laminate included in the solid-state battery will be described in detail. Although the description will be given with reference to the drawings as necessary, the contents shown in the drawings are merely shown as schematic examples for understanding the present invention, and the appearance and dimensional ratios may differ from the actual product.

[0014] In this specification, the term "cross-sectional view" refers to the shape of the solid-state battery when viewed from a direction approximately perpendicular to any thickness direction of the solid-state battery (in simple terms, for example, the shape when cut along a plane parallel to the thickness direction). The terms "upper and lower directions" and "left and right directions" used directly or indirectly in this specification correspond to the upper and lower directions and left and right directions in the drawings, respectively. The terms "front-rear direction" and "back-rear direction" used directly or indirectly in this specification correspond to the front-rear direction on the paper in the drawings. Unless otherwise specified, the same symbols or symbols indicate the same components or parts or have the same meanings. In a preferred embodiment, the vertically downward direction (i.e., the direction in which gravity acts) can be considered to correspond to the "downward direction" / "bottom side", and the opposite direction can be considered to correspond to the "upward direction" / "top side".

[0015] In the present invention, the term "solid-state battery" refers in a broad sense to a battery whose constituent electrolyte is made of a solid, and in a narrow sense to an all-solid-state battery whose constituent elements (particularly preferably all constituent elements) are made of a solid. In a preferred embodiment, the solid-state battery of the present invention is a laminated solid-state battery in which each layer constituting a battery constituent unit is laminated on top of each other, and preferably each such layer is made of a sintered body. The term "solid-state battery" includes not only so-called "secondary batteries" capable of repeated charging and discharging, but also "primary batteries" capable of only discharging. According to a preferred embodiment of the present invention, the "solid-state battery" is a secondary battery. The term "secondary battery" is not excessively limited to its name, and may include, for example, a power storage device.

[0016] In the following, first, the basic structure of the "solid-state battery" of the present invention will be described, and then the features of the solid-state battery of the present invention (particularly the "exterior member") will be described. The structure of the solid-state battery described here is merely an example for understanding the invention, and does not limit the invention.

[0017] [Basic structure of solid-state batteries] A solid-state battery comprises at least positive and negative electrode layers and a solid electrolyte layer (or solid electrolyte). Specifically, as shown in Fig. 1, a solid-state battery comprises a solid-state battery stack 10 (hereinafter sometimes referred to as a "battery body") that comprises at least one battery structural unit 5 along the stacking direction, the battery structural unit 5 comprising a positive electrode layer 1, a negative electrode layer 2, and a solid electrolyte layer (or solid electrolyte) 3 interposed therebetween.

[0018] In the solid-state battery of the present disclosure, there are no particular limitations on the laminate structure of the battery, in particular on the structure of the battery constituent units. The solid-state battery of the present disclosure may be a single cell including only a battery constituent unit composed of a positive electrode layer, a negative electrode layer, and a solid electrolyte layer (or solid electrolyte) interposed therebetween. In the solid-state battery of the present disclosure, such battery constituent units may be arranged in series or in parallel. From the viewpoint of stress dispersion, the battery constituent units may be arranged in parallel.

[0019] Preferably, the solid-state battery may have each of its constituent layers formed by firing, and the positive electrode layer, the negative electrode layer, the solid electrolyte layer, etc. may form sintered layers. For example, the positive electrode layer, the negative electrode layer, and the solid electrolyte layer may be fired together with each other, and thus the solid-state battery laminate may form an integral sintered body.

[0020] The positive electrode layer 1 is an electrode layer comprising at least a positive electrode active material. Thus, the positive electrode layer 1 may be a positive electrode active material layer mainly composed of a positive electrode active material. The positive electrode layer may further comprise a solid electrolyte, if necessary. In one embodiment, the positive electrode layer may be composed of a sintered body comprising at least positive electrode active material particles and solid electrolyte particles. On the other hand, the negative electrode layer 2 is an electrode layer that includes at least a negative electrode active material. Therefore, the negative electrode layer 2 may be a negative electrode active material layer that is mainly composed of a negative electrode active material. The negative electrode layer may further include a solid electrolyte, if necessary. In one embodiment, the negative electrode layer may be composed of a sintered body that includes at least negative electrode active material particles and solid electrolyte particles.

[0021] The positive electrode active material and the negative electrode active material are materials involved in the absorption and release of ions and the transfer of electrons to and from an external circuit in a solid-state battery. For example, ions move (conduct) between the positive electrode layer and the negative electrode layer via a solid electrolyte. The absorption and release of ions in the active material is accompanied by the oxidation or reduction of the active material, and the electrons or holes for such an oxidation-reduction reaction are transferred from the external circuit to the external terminal of the solid-state battery, and further to the positive electrode layer or the negative electrode layer, thereby proceeding with charging and discharging. The positive electrode layer and the negative electrode layer may be layers capable of absorbing and releasing lithium ions or sodium ions in particular. In other words, the solid-state battery may be an all-solid-state secondary battery in which lithium ions or sodium ions move between the positive electrode layer and the negative electrode layer via a solid electrolyte to charge and discharge the battery.

[0022] (Cathode active material) The positive electrode active material that can be contained in the positive electrode layer 1 may be at least one selected from the group consisting of a lithium-containing phosphate compound having a Nasicon structure, a lithium-containing phosphate compound having an olivine structure, a lithium-containing layered oxide, and a lithium-containing oxide having a spinel structure. An example of a lithium-containing phosphate compound having a Nasicon structure is Li3V2(PO4)3. An example of a lithium-containing phosphate compound having an olivine structure is Li3Fe2(PO4)3, LiFePO4, LiMnPO4, LiFe 0.6 Mn 0.4 Examples of lithium-containing layered oxides include LiCoO2, LiCo 1 / 3 Ni 1 / 3 Mn 1 / 3 O2, LiCo 0.8 Ni 0.15 Al 0.05Examples of lithium-containing oxides having a spinel structure include LiMn2O4, LiNi 0.5 Mn 1.5 Examples include O4.

[0023] In addition, examples of positive electrode active materials capable of absorbing and releasing sodium ions include at least one selected from the group consisting of sodium-containing phosphate compounds having a Nasicon structure, sodium-containing phosphate compounds having an olivine structure, sodium-containing layered oxides, and sodium-containing oxides having a spinel structure.

[0024] (Negative electrode active material) Examples of the negative electrode active material that can be included in the negative electrode layer 2 include at least one 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-containing phosphate compounds having a Nasicon structure, lithium-containing phosphate compounds having an olivine structure, and lithium-containing oxides having a spinel structure. An example of a lithium alloy is Li-Al. An example of a lithium-containing phosphate compound having a Nasicon structure is Li3V2(PO4)3, LiTi2(PO4)3, etc. An example of a lithium-containing phosphate compound having an olivine structure is Li3Fe2(PO4)3, LiCuPO4, etc. An example of a lithium-containing oxide having a spinel structure is Li4Ti5O 12 etc.

[0025] In addition, examples of negative electrode active materials capable of absorbing and releasing sodium ions include at least one selected from the group consisting of sodium-containing phosphate compounds having a Nasicon structure, sodium-containing phosphate compounds having an olivine structure, and sodium-containing oxides having a spinel structure.

[0026] The positive electrode layer and / or the negative electrode layer may contain a conductive assistant. The conductive assistant that may be contained in the positive electrode layer and the negative electrode layer may include at least one selected from the group consisting of metal materials such as silver, palladium, gold, platinum, copper, and nickel, and carbon.

[0027] Furthermore, the positive electrode layer and / or the negative electrode layer may contain a sintering aid, which may be at least one selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, boron oxide, silicon oxide, bismuth oxide, and phosphorus oxide.

[0028] (solid electrolyte) The solid electrolyte 3 is, for example, a material capable of conducting lithium ions or sodium ions. In particular, the solid electrolyte constituting the battery constituent unit in a solid-state battery forms a layer capable of conducting, for example, lithium ions between the positive electrode layer and the negative electrode layer. Specific examples of the solid electrolyte include lithium-containing phosphate compounds having a Nasicon structure, oxides having a perovskite structure, oxides having a garnet structure or a garnet-like structure, oxide glass ceramics-based lithium ion conductors, and the like. Examples of lithium-containing phosphate compounds having 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). An example of a lithium-containing phosphate compound having a Nasicon structure is Li 1.2 Al 0.2 Ti 1.8 (PO4)3, etc. An example of an oxide having a perovskite structure is La 0.55 Li 0.35 An example of an oxide having a garnet-type or garnet-like structure is Li7La3Zr2O 12Examples of the oxide glass ceramic lithium ion conductor that can be used include a phosphate compound containing lithium, aluminum, and titanium as constituent elements (LATP) and a phosphate compound containing lithium, aluminum, and germanium as constituent elements (LAGP). Examples of solid electrolytes capable of conducting sodium ions include sodium-containing phosphate compounds having a Nasicon structure, oxides having a perovskite structure, and oxides having a garnet structure or a garnet-like structure. Examples of sodium-containing phosphate compounds having a Nasicon structure include 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).

[0029] The solid electrolyte layer may contain a sintering aid. The sintering aid that may be contained in the solid electrolyte layer may be selected from the same materials as the sintering aids that may be contained in the positive electrode layer and / or the negative electrode layer, for example.

[0030] (Positive and negative electrode current collecting layers) The positive electrode layer 1 and the negative electrode layer 2 may each include a positive electrode current collecting layer and a negative electrode current collecting layer. The positive electrode current collecting layer and the negative electrode current collecting layer may each have the form of a foil, but may have the form of a sintered body from the viewpoint of reducing the manufacturing cost of the solid battery by co-firing and reducing the internal resistance of the solid battery. When the positive electrode current collecting layer and the negative electrode current collecting layer have the form of a sintered body, they may be composed of a sintered body containing a conductive assistant and a sintering assistant. The conductive assistant that may be contained in the positive electrode current collecting layer and the negative electrode current collecting layer may be selected from, for example, the same material as the conductive assistant that may be contained in the positive electrode layer and / or the negative electrode layer. The sintering assistant that may be contained in the positive electrode current collecting layer and / or the negative electrode current collecting layer may be selected from, for example, the same material as the sintering assistant that may be contained in the positive electrode layer and / or the negative electrode layer. In addition, the positive electrode current collecting layer and / or the negative electrode current collecting layer are not essential in the solid battery, and a solid battery without such a positive electrode current collecting layer and / or a negative electrode current collecting layer is also conceivable. In other words, the solid-state battery in the present invention may be a "current collector-less" solid-state battery.

[0031] (External terminal) The solid-state battery stack 10 may be provided with a terminal for connection to the outside (or an external device) (hereinafter, referred to as an "external terminal"). In particular, it is preferable that a terminal for connection to the outside is provided as an "end electrode" on the side surface of the solid-state battery stack 10. More specifically, as the external terminal, a positive electrode side terminal (positive electrode terminal) that can be electrically connected to the positive electrode layer 1 and a negative electrode side terminal (negative electrode terminal) that can be electrically connected to the negative electrode layer 2 may be provided (see, for example, 53A and 53B in FIG. 6 and 63A and 63B in FIG. 7). Such a terminal is preferably made of a material having a high electrical conductivity (or a conductive material). The material of the external terminal is not particularly limited, but may be at least one selected from the group consisting of gold, silver, platinum, tin, nickel, copper, manganese, cobalt, iron, titanium, and chromium.

[0032] [Features of the Solid-State Battery Disclosed Herein] A solid-state battery according to an embodiment of the present disclosure (hereinafter, sometimes referred to as the "solid-state battery of the present disclosure" or simply as the "solid-state battery" or "battery") includes a solid-state battery stack 10 (hereinafter, sometimes referred to as the "battery body") including at least one battery unit 5 along the stacking direction (or thickness direction or vertical direction) including a positive electrode layer 1, a negative electrode layer 2, and a solid electrolyte layer (or solid electrolyte) 3 interposed between the positive electrode layer 1 and the negative electrode layer 2, as shown in FIG. 1, for example. Furthermore, the solid-state battery according to the present disclosure can include a positive electrode terminal and a negative electrode terminal as external terminals that can be provided on the opposing left and right side surfaces of the solid-state battery stack, respectively (more specifically, see the external terminal 53 (more specifically, the positive electrode terminal 53A and the negative electrode terminal 53B) of the embodiment shown in FIG. 6 and the external terminal 63 (more specifically, the positive electrode terminal 63A and the negative electrode terminal 63B) shown in FIG. 7).

[0033] The solid-state battery of the present disclosure preferably includes an exterior member 11 that covers the battery body, as shown in Fig. 2, for example. It is preferable that a void 13 is present on the inner side (or interior) of the exterior member 11, adjacent to the battery body (more specifically, see also voids (53, 53') that may be included in the exterior members (51, 51') of the embodiment shown in Fig. 6).

[0034] In the present disclosure, "the side of the exterior member adjacent to the battery body (or the solid-state battery stack)" basically means a part or region that is inside or inside the exterior member and is geometrically close to or in contact with the battery body or the interface (the interface between the exterior member and the battery body). In the present disclosure, "the side of the exterior member adjacent to the battery body (or solid-state battery stack)" may also include the portion where the exterior member is in contact with the battery body, the boundary or interface between the exterior member and the battery body, and other layers that may be formed between the exterior member and the battery body (for example, an intermediate layer or a mixed layer that may be formed during manufacture).

[0035] In the present disclosure, the terms "boundary" and "interface" basically refer to the geometric boundary between the exterior member and the battery body. Such a boundary may also be included in the "side of the exterior member adjacent to the battery body (or solid-state battery laminate)."

[0036] For example, it is preferable that a gap 13 is present in the inner region of the exterior member 11 (see FIG. 2). In the present disclosure, the "inner region" refers to the region of the exterior member that is closer to the battery body. More specifically, the region indicated by the height of symbol H1 in FIG. 2 can be referred to as the "inner region". Therefore, in the present disclosure, the region of the exterior member that is farther from the battery body can be referred to as the "outer region".

[0037] In the present disclosure, the "inner region" may also include the portion where the exterior member is in contact with the battery body, the boundary or interface between the exterior member and the battery body, and other layers that may be formed between the exterior member and the battery body (e.g., intermediate layers or mixed layers that may be formed during manufacture).

[0038] The "existence of a gap on the inner side of the exterior member adjacent to the battery body (or solid-state battery stack)" and "existence of a gap in the inner region of the exterior member" will be briefly described with reference to FIG. 9, for example.

[0039] 9(A) shows a typical example of a void present inside an exterior member. The void may have an irregular, regular or geometric shape. In the present disclosure, such a case can also be interpreted as "a gap exists on the side of the exterior member adjacent to the battery body (or solid-state battery stack)" or "a gap exists in the inner region of the exterior member."

[0040] Fig. 9(B) is a schematic diagram showing a typical case where a void exists in a portion where the exterior member is in contact with the battery body. As shown in Fig. 9(B), at least a part of the void may exist in contact with the boundary or interface between the exterior member and the battery body. In the present disclosure, such a case can also be interpreted as "a gap exists on the side of the exterior member adjacent to the battery body (or solid-state battery stack)" or "a gap exists in the inner region of the exterior member."

[0041] Fig. 9(C) shows a case where a void exists inside the exterior member. However, in Fig. 9(C), an intermediate layer or a mixed layer is located between the exterior member and the battery body as another layer that may be formed during manufacturing. There is no particular limit to the thickness of the intermediate layer or the mixed layer. In Fig. 9(C), at least a part of the void exists in contact with the boundary or interface between the exterior member and the intermediate layer or the mixed layer. In the present disclosure, an "intermediate layer or mixed layer that may be formed during manufacturing" refers to any layer that may be located between an exterior member that may be formed during manufacturing and a battery main body (or a solid-state battery stack), and may be a layer in which a component or element that may be included in the exterior member and a component or element that may be included in the battery main body (or a solid-state battery stack) are mixed. In the present disclosure, such a case can also be interpreted as "a gap exists on the side of the exterior member adjacent to the battery body (or solid-state battery stack)" or "a gap exists in the inner region of the exterior member."

[0042] 9(D) shows that voids exist in an intermediate layer or a mixed layer that may be formed between the battery body and the exterior member, at least a part of which may be in contact with the boundary or interface between the exterior member and the battery body. In the present disclosure, such a case can also be interpreted as "a gap exists on the side of the exterior member adjacent to the battery body (or solid-state battery stack)" or "a gap exists in the inner region of the exterior member."

[0043] Hereinafter, the solid-state battery of the present disclosure, in particular the "exterior member" that may contain such voids, and particularly the "glass component", will be described in further detail with reference to FIG.

[0044] The exterior member 11 shown in Fig. 2 is capable of covering the periphery of the battery body, and more specifically, is a member capable of covering all of the surrounding surfaces except for the left and right side surfaces (or end surfaces) on which the external terminals of the battery body are provided (more specifically, see the exterior members (51, 51') in Fig. 6, etc.). Note that the exterior member 11, as shown in Fig. 2, for example, contains a glass component 12, which will be described in detail below, as a base material or matrix, and can function as a covering layer for the battery body.

[0045] Moreover, the exterior member 11 shown in FIG. 2 is disposed adjacent to or in contact with (for example, directly contacting) the solid-state battery stack, that is, the battery main body, below it (see, for example, FIG. 6).

[0046] The solid-state battery of the present disclosure is mainly characterized in that, as shown in Fig. 2, voids 13 are present in an inner region (e.g., below the exterior member 11 shown in Fig. 2) adjacent to the battery main body (e.g., the solid-state battery laminate 10 in Fig. 1) (or interface) inside (or inside) the exterior member 11 (more specifically, see Fig. 8). For convenience of explanation, the voids 13 are shown in the shape of a sphere with a circular cross section, but the shape of the voids 13 is not necessarily limited to a sphere.

[0047] For example, as shown in Fig. 2, by distributing voids 13 in an inner region of exterior member 11, voids 13 can act as a cushion to relieve stress that may occur due to volume expansion and contraction of the battery body during charging and discharging of the solid-state battery. This in turn can suppress or prevent cracking or chipping of exterior member 11, thereby suppressing or preventing the intrusion of water vapor or moisture into the battery body. In other words, voids 13 can further improve gas barrier properties against water vapor and the like.

[0048] In addition, in the solid-state battery of the present disclosure, it is preferable that the outer region of the exterior member 11, preferably the outer half (or upper half), contains relatively more glass component 12 than the inner region, preferably the inner half (or lower half), as shown in FIG. 2, for example. This configuration can also prevent or suppress the intrusion of water vapor and moisture into the battery body. In addition to the gas barrier properties, the strength, impact resistance, airtightness, moisture resistance, etc. of the exterior member 11 can be improved. Below, the "exterior member" and the "voids" and "glass components" contained therein will be described in more detail.

[0049] (Exterior materials) In the present disclosure, the term "exterior member" refers to a coating layer or exterior layer that can preferably cover the entire battery body of a solid-state battery (e.g., solid-state battery stack 10 shown in FIG. 1) and contains, for example, a "glass component" as a base material or matrix, which will be described in detail below. Such an exterior member is preferably composed of a sintered body containing a glass component or the like.

[0050] In the present disclosure, the term "glass component" refers to a composition or material containing glass as a main component (hereinafter, sometimes referred to as "glass material"). The glass material is not particularly limited, and may be at least one selected from the group consisting of silica glass (glass containing silicon oxide, silicon oxynitride, etc. as a main component), soda-lime glass, potash glass, borate-based glass, borosilicate-based glass, barium borosilicate-based glass, zinc borate-based glass, barium borate-based glass, bismuth borosilicate-based glass, bismuth zinc borate-based glass, bismuth silicate-based glass, phosphate-based glass, aluminophosphate-based glass, and zinc phosphate-based glass.

[0051] In this disclosure, "void" refers to one or more spaces or gaps or voids or cavities that may be formed within an exterior member (particularly a glass material). Exterior members (particularly glass materials) are generally airtight but hard and brittle. However, by forming a gap inside an exterior member (particularly a glass material) as in the present disclosure, it is possible to significantly prevent the occurrence of cracks, chips, and the like in such an exterior member while ensuring the gas barrier properties.

[0052] There is no particular limitation on the shape of the voids, in other words, they may have any shape, and the shape of the voids may be geometrically regular or irregular. For example, as shown in Fig. 2, the voids may be spherical with a cross section of a substantially circular shape, or may have a cross section of an ellipse, a rugby ball shape, a substantially triangular shape, a substantially rectangular shape, a substantially polygonal shape, a substantially cross shape, and / or a substantially star shape, or a random shape (see Fig. 9). Therefore, the exterior member (particularly the glass material) may have a random mixture of voids with a plurality of different shapes and dimensions.

[0053] The shape of the voids is ideally a sphere with a circular cross section. Also, it is preferable that the shape is close to a sphere with a circular cross section. From this viewpoint, the circularity may be within a range of 0.1 to 1.0.

[0054] There is no particular limitation on the dimensions of the gap. For example, as shown in FIG. 2, when the cross-sectional shape is approximately circular, the diameter or maximum diameter may be taken as the dimension of the gap. When the cross-sectional shape of the gap is another shape, the diameter calculated by converting the cross-sectional shape into a circle may be taken as the dimension of the gap. The size of the voids is, for example, within the range of 1 μm to 20 μm, and the average size of the voids that may be contained in the exterior member (particularly the glass material) is, for example, within the range of 3 μm to 20 μm. The size of such voids can be determined by image processing such as binarization of an electron microscope photograph of a cross section of the exterior member. Binarization will be described in detail below.

[0055] (cross section) More specifically, the cross section of the exterior member can be formed by the following method. For example, a solid-state battery is hardened with resin and then cut to the vicinity of the observation surface. The cut surface is polished with abrasive paper or the like to make it the observation surface. The polishing method is not particularly limited, but can be rough grinding using coarse abrasive paper, followed by polishing using abrasive paper or abrasives with small abrasive grain size. In addition, an automatic polishing machine, abrasive paper, ion milling, or chemical mechanical polishing (CMP) can be used for polishing. The polished surface after surface preparation can be imaged with an electron microscope and binarized using image processing software, and the porosity and / or pore size can be calculated. In addition, the cut surface for cross-sectional observation of the exterior member may be processed so that either surface serves as the bottom surface, but it is preferable to process the cut surface perpendicular to the bottom surface. Also, the cutting surface may be placed toward the front and processed at a position halfway along the depth (see FIG. 10, for example). There are no limitations on how the cross section is exposed, but it is preferable that the cross section is smooth. For example, a smooth cross section for observation can be obtained by embedding the sample in a cured resin, polishing it to expose the cross section, and then processing it by ion milling.

[0056] (void) The voids can be formed, for example, by using a void-forming agent when forming the exterior member, or by intentionally reducing the amount of the glass component. Such voids may include voids that may be formed as bubbles inside the exterior member due to gases (e.g., O2, CO2, CO, etc.) that may be generated during firing when the exterior member is formed by integral firing together with each layer that may be included in the battery body (i.e., when the battery body is formed as an integral sintered body). The void-forming agent may be, for example, an organic substance, such as a polymer (which is merely an example, but may be a polymer such as a polyolefin such as polyethylene and / or polypropylene). For example, an organic substance such as a binder (e.g., a polymer such as polypropylene) may be vaporized during firing, forming bubbles and thus voids inside the exterior member.

[0057] The void 13 may be present on the inside (or underside) of the exterior member 11 adjacent to the battery body (or interface) in the exterior member 11 shown in FIG. 2, for example. In other words, the void 13 may be present in an inner region of the exterior member 11 adjacent to the battery body (or interface), preferably in the inner half (or lower half). The void 13 may be in contact with the interface between the exterior member 11 and the battery body. In addition, the cross-sectional shape of the void is not necessarily limited to a circle.

[0058] More specifically, as shown in FIG. 2, it is preferable that gap 13 exists in a region in the thickness direction indicated by height H1 which is 50% or less, preferably 35% or less, of height H0 in the thickness direction of exterior member 11.

[0059] In addition, in the solid-state battery of the present disclosure, it is preferable that the inner region adjacent to the battery body (or interface) of the exterior member 11, preferably the inner half (or lower half), has a higher porosity than the outer half (or upper half), or that the voids 13 are relatively numerous. In other words, it is preferable that the voids 13 are unevenly distributed in the exterior member 11 in a thickness direction region indicated by H1 that is 50% or less of the height H0 in the thickness direction. Therefore, in the solid-state battery of the present disclosure, although the voids 13 may also be present in the outer region, preferably the outer half (or upper half), of the exterior member 11, it is preferable that the number, area, or volume of the voids 13 present in the inner region, preferably the inner half (or lower half), is greater than the number, area, or volume of the voids present in the outer region.

[0060] The height H0 of the exterior member 11 in the thickness direction is, for example, 500 μm or less.

[0061] In this way, the presence of more voids in the inner region adjacent to the battery body (or interface) inside the exterior member 11 can further mitigate expansion and contraction of the battery body and suppress cracking and chipping, thereby further improving the gas barrier properties.

[0062] Furthermore, inside the exterior member 11, the voids 13 may be unevenly distributed in a region indicated by a length L1 that is, for example, less than 100%, preferably 90% or less, of the length L0 of the exterior member 11 (e.g., the length perpendicular to the stacking direction of the solid-state battery stack) (i.e., from both ends of the exterior member 11).

[0063] The voids 13 may exist in a cross-sectional view at a ratio of, for example, 2% to 20%, and preferably 3% to 15%, of the total area of ​​the exterior member 11. Such a ratio can be determined by image processing such as binarization of an electron microscope photograph of the cross section of the exterior member.

[0064] In the solid-state battery of the present disclosure, the exterior member may preferably be a water vapor barrier film. In other words, the exterior member covers the top and bottom surfaces as well as the front and rear surfaces of the solid-state battery so as to preferably serve as a barrier to prevent moisture from entering the solid-state battery. In the broad sense, the term "barrier" used in this specification means that the exterior member has a water vapor permeability preventing property to such an extent that water vapor from the external environment does not pass through the exterior member and cause inconvenient deterioration of the characteristics of the solid-state battery. In the narrow sense, the term "barrier" means that the exterior member has a water vapor permeability of 1.0×10 -3 g / (m 2 Therefore, in short, the water vapor barrier film is preferably 0 to 1.0×10 -3 g / (m 2 ·Day). The "water vapor permeability" here refers to the permeability measured using a gas permeability measuring device, Model GTms-1, manufactured by Advance Riko Co., Ltd., under measurement conditions of 40°C, 90% RH, and a differential pressure of 1 atm. In particular, in the case of a Nasicon-type structure, the solid-state battery has a capacity of 1.0×10 -3 g / (m 2 It is preferable that the water vapor transmission rate is less than 100%.

[0065] The exterior member 11, particularly the glass component 12, may further contain an inorganic filler 24, for example as shown in FIG.

[0066] The inorganic filler 24 is not particularly limited and may be at least one selected from the group consisting of various ceramics, such as oxides, nitrides, and carbides, such as alumina, silica, and zirconia, etc. By adding such an inorganic filler, it is possible to further improve, for example, strength, impact resistance, airtightness, and / or moisture resistance.

[0067] The inorganic filler 24 may or may not be unevenly distributed in the exterior member 21. The inorganic filler 24 may be uniformly dispersed. The inorganic filler 24 is present in a proportion of, for example, 10% to 90% of the total area of ​​the exterior member 21 in a cross-sectional view. This proportion can be determined by image processing such as binarization from an electron microscope photograph of a cross-section of the exterior member.

[0068] In addition, the exterior member 21, glass component 22, and void 23, as well as the height H2 and length L2 in the thickness direction, shown in Figure 3, can correspond to the exterior member 11, glass component 12, and void 13, as well as the height H1 and length L1 in the thickness direction, shown in Figure 2, respectively.

[0069] In the solid-state battery of the present disclosure, the exterior member may have, for example, a "two-layer structure" composed of a "first exterior member" and a "second exterior member", or may have a structure of two or more layers (for example, an intermediate layer or mixed layer that may be formed during manufacture, a third exterior member, a fourth exterior member, a fifth exterior member, etc.). In an embodiment, in the solid-state battery of the present disclosure, the exterior member preferably has a structure of two or more layers.

[0070] For example, in the embodiment shown in FIG. 4, the exterior member (for example, the exterior member 11 shown in FIG. 2) may have a configuration in which the exterior member is separated into two layers, a first exterior member 31 and a second exterior member . In the embodiment shown in FIG. 4, for example, the solid-state battery stack 10 shown in FIG.

[0071] 4, it is preferable that the first exterior member 31 is provided adjacent to the battery body (or interface), that the second exterior member 35 is provided adjacent to the first exterior member 31 on the side opposite to the battery body, and that voids 33 exist in the first exterior member 31. Note that in the solid-state battery of the present disclosure, voids may exist in the second exterior member 35, but it is preferable that the number, area, or volume of voids is smaller than the number, area, or volume of voids 33 contained in the first exterior member 31.

[0072] It is preferable that the first exterior member 31 and the second exterior member 35 each independently contain a glass component (or glass material) (32, 36), and that voids 33 exist in the glass component 32 of the first exterior member 31. Note that the voids 33 contained in the first exterior member 31 (specifically, the glass component 32) can correspond to the voids 13 in Fig. 2, and the glass components (32, 36) that can be contained in the first exterior member 31 and the second exterior member 35 can each independently use the glass components described above (hereinafter, the glass component that can be contained in the first exterior member 31 will be referred to as the "first glass component 32", and the glass component that can be contained in the second exterior member 35 will be referred to as the "second glass component 36").

[0073] In first exterior member 31 shown in FIG. 4, first glass component 32 is preferably present at a ratio of, for example, 10% to 60% of the total area of ​​first exterior member 31 in cross section.

[0074] In the embodiment shown in FIG. 4, the thickness T1 of the first exterior member 31 is equal to the total thickness T a It is preferable that the thickness is 50% or less of ("thickness T1 of the first exterior member 31" + "thickness T2 of the second exterior member 35").

[0075] In the second exterior member 35 shown in FIG. 4, the second glass component 36 is present in a proportion of, for example, 100% or less, preferably 30% to 80%, relative to the total area of ​​the second exterior member 35 in a cross-sectional view.

[0076] In the embodiment shown in FIG. 4, the thickness T2 of the second exterior member 35 is equal to the total thickness T a It is preferable that the ratio is greater than 50%.

[0077] The first exterior member 31 and the second exterior member 35 may each independently further contain the inorganic filler described above.

[0078] Each of the first exterior member 31 and the second exterior member 35 may contain an inorganic filler.

[0079] Alternatively, either the first exterior member 31 or the second exterior member 35 may contain an inorganic filler.

[0080] 5, the first exterior member 41 may include a first inorganic filler 44, and the second exterior member 45 may include a second inorganic filler 47. The first inorganic filler 44 that may be included in the first exterior member 41 and the second inorganic filler 47 that may be included in the second exterior member 45 may be the same or different.

[0081] In the embodiment shown in Fig. 5, a first glass component 42 and voids 43 that may be contained in a first exterior member 41 may correspond to the first glass component 32 and voids 33 that may be contained in the first exterior member 31 shown in Fig. 4. Also, a second glass component 46 that may be contained in a second exterior member 45 shown in Fig. 5 may correspond to the second glass component 36 shown in Fig. 4.

[0082] 5, the ratio of the first glass component 42 in the first exterior member 41 is preferably 20% or less of the total volume of the first exterior member 41. The presence of the glass component at such a ratio ensures a more sufficient amount of voids 43 in the first exterior member 41. Therefore, the multiple voids 43 act as a cushion to relieve stress that may be generated due to volumetric expansion and contraction of the battery body during charging and discharging of the solid-state battery, and thus cracking and chipping of the first exterior member 41 can be suppressed or prevented. As a result, the intrusion of water vapor and moisture into the battery body can be suppressed or prevented.

[0083] 5, the proportion of the second glass component 46 in the second exterior member 45 is preferably 50% or more with respect to the total volume of the second exterior member 45. The presence of the glass component at such a proportion ensures a more sufficient amount of the glass component in the second exterior member 45. Therefore, the strength, impact resistance, airtightness, and / or moisture resistance of the second exterior member 45 can be improved.

[0084] 5, the role of each layer can be clarified by dividing the exterior member into at least two layers, a first exterior member 41 and a second exterior member 45. Therefore, in the solid-state battery of the present disclosure, the exterior member preferably has a two-layer structure or a structure of two or more layers.

[0085] In the case of the exterior member of the present disclosure, when the exterior member has a structure of two or more layers, the boundary between the layers does not necessarily have to be linear. In addition, depending on the type of glass component selected, for example, when the same glass component is used, the boundary between the layers may not be visible to the naked eye or with a microscope, etc.

[0086] In the solid-state battery of the present disclosure, when the exterior member is a sintered body, the boundary between the glass component and the inorganic filler may not be visible or visible with a microscope, depending on the material selected, for example, when ceramic is used as the inorganic filler.

[0087] A Preferred Embodiment As merely one example, a preferred embodiment of the solid-state battery of the present disclosure is shown in FIG. 6 as a "solid-state battery 50". The solid-state battery 50 may include a solid-state battery laminate (i.e., a battery body) including at least one battery unit 5 including a positive electrode layer 1, a negative electrode layer 2, and a solid electrolyte layer 3 interposed therebetween, for example, as shown in FIG. 1, arranged, for example, along the stacking direction. On the opposing left and right side surfaces (or end faces) of such a battery body, external terminals 53, for example, a positive electrode terminal 53A and a negative electrode terminal 53B, may be provided facing each other. The solid-state battery 50 includes exterior members (51, 51') that cover the battery body.

[0088] More specifically, the solid-state battery 50 is provided with exterior members (51, 51') that cover the periphery (upper and lower surfaces and front and rear surfaces) of the battery body except for the left and right side surfaces (or end surfaces). In the cross-sectional view shown in Fig. 6, exterior members 21 as shown in Fig. 3, for example, are arranged above and below the battery body so as to face each other vertically (see, for example, the exterior members (51, 51') shown in Fig. 6). In the illustrated embodiment, external terminals (53A, 53B) are also arranged on the left and right side surfaces (or end surfaces) of the exterior members (51, 51'), but the left and right side surfaces of the exterior members (51, 51') may or may not be covered with such external terminals.

[0089] A void (53, 53') may be present on the inner side (e.g., the inner region, preferably the inner half) of the exterior member (51, 51') that can cover the battery body and that is adjacent to the battery body (or the interface). Therefore, the void (53, 53') can relieve stress that may be generated due to the volumetric expansion and contraction of the battery body during charging and discharging of such a solid-state battery, and thus cracking or chipping of the exterior member (51, 51') can be suppressed or prevented. As a result, the intrusion of water vapor or moisture into the battery body can be suppressed or prevented.

[0090] Moreover, the proportion of the glass component (52, 52') is high in the outer region, preferably the outer half, of the exterior member (51, 51'), which further improves the gas barrier property against water vapor and the like in the exterior member (51, 51').

[0091] Furthermore, since an inorganic filler (54, 54') may be contained inside the exterior member (51, 51') that covers the battery body, the strength, impact resistance, airtightness, and / or moisture resistance of the exterior member (51, 51') can be further improved.

[0092] In the solid-state battery 50, the exterior members (51, 51') may be changed to the exterior member 11 shown in FIG.

[0093] Another preferred embodiment of the solid-state battery of the present disclosure is shown in FIG. 7 as a "solid-state battery 60". The solid-state battery 60 may include a solid-state battery laminate (i.e., a battery body) including at least one battery unit 5 including a positive electrode layer 1, a negative electrode layer 2, and a solid electrolyte layer 3 interposed therebetween, for example, as shown in FIG. 1, arranged, for example, along the stacking direction. A positive electrode terminal 63A and a negative electrode terminal 63B may be provided facing each other as external terminals 63 on the opposing left and right side surfaces (or end faces) of such a battery body. The solid-state battery 60 includes a first exterior member (61, 61') and a second exterior member (65, 65') as exterior members of a two-layer structure that cover the battery body.

[0094] More specifically, the solid-state battery 60 may be provided with a first exterior member (61, 61') and a second exterior member (65, 65') that cover the periphery (upper and lower surfaces and front and rear surfaces) of the battery body except for the left and right side surfaces (or end surfaces). In the cross-sectional view shown in FIG. 7, the first exterior member (61, 61') and the second exterior member (65, 65') are arranged above and below the battery body so as to face each other vertically as a two-layer structure (see FIG. 5). In the illustrated embodiment, external terminals (63A, 63B) are also arranged on the left and right side surfaces (or end surfaces) of the first exterior member (61, 61') and the second exterior member (65, 65'), but the left and right side surfaces of the first exterior member (61, 61') and the second exterior member (65, 65') may or may not be covered with such external terminals.

[0095] The first exterior member (61, 61') that directly covers the battery body may have voids (63, 63'). Therefore, the voids (63, 63') can relieve stress that may occur due to volume expansion or contraction of the battery body during charging and discharging of such a solid-state battery, and thus cracking or chipping of the first exterior member (61, 61') can be suppressed or prevented. As a result, the intrusion of water vapor or moisture into the battery body can be suppressed or prevented.

[0096] Furthermore, the second exterior member (65, 65') has a higher proportion of glass components (66, 66') than the first exterior member (61, 61'). This makes it possible to further improve the gas barrier properties of the second exterior member (65, 65') against water vapor and the like.

[0097] Since the first exterior member (61, 61') and the second exterior member (65, 65') that cover the battery body may contain a first inorganic filler (64, 64') and a second inorganic filler (67, 67'), respectively, the strength, impact resistance, airtightness, and / or moisture resistance of the first exterior member (61, 61') and the second exterior member (65, 65'), particularly the second exterior member (65, 65'), can be further improved.

[0098] In the solid-state battery 60, the first exterior member (61, 61') and the second exterior member (65, 65') may be changed to the first exterior member 31 and the second exterior member 35 shown in FIG.

[0099] In addition, in any of the above embodiments, the solid-state battery can be used in a wide range of temperatures because the voids that may be included in the exterior member can be expected to provide a heat insulating effect. For example, the solid-state battery of the present disclosure can withstand mounting of the solid-state battery to a substrate by reflow soldering or the like. Therefore, the solid-state battery of the present disclosure can be used as a chip-type surface-mount device (SMD).

[0100] In the above embodiment, it is preferable that the positive electrode layer 1 and the negative electrode layer 2 are layers capable of absorbing and releasing lithium ions. With such a configuration, the secondary battery of the present disclosure can be used as a lithium ion secondary battery.

[0101] The solid-state battery of the present disclosure is not limited to the above embodiment. The solid-state battery of the present disclosure can be manufactured, for example, by a printing method such as a conventionally known screen printing method, a green sheet method using a green sheet, or a combination method thereof. However, the manufacturing method of the solid-state battery of the present disclosure is not limited to the above method.

[0102] (Binarization) Binarization can be performed, for example, using “Fiji imageJ” (https: / / imagej.net / Fiji), which is an open source, public domain image processing software.

[0103] For example, a cross-sectional photograph taken by an electron microscope as shown in Figure 11 is binarized using the image processing software "Fiji imageJ" and the porosity, etc. are calculated.

[0104] The porosity of each of the "exterior material (outer)" and "exterior material (inner)" can be binarized by dividing it into "exterior material (outer)" and "exterior material (inner)" as shown in Figure 12, for example.

[0105] There are no particular limitations on the conditions for binarization as long as the voids can be recognized. For example, in the image processing software "Fiji imageJ," binarization can be performed with the default setting of "Default" or "Auto" (see Figure 13).

[0106] When the boundary between the "exterior member (inside)" and the "battery body (or solid-state battery laminate)" is not clear (see, for example, FIG. 14(A)), the boundary may be made clearer by drawing a line such as a white line using, for example, a drawing function (see FIG. 14(B)). For example, the thickness of the white line may be set to a pixel count of 1 μm or less. Note that such lines such as white lines can be construed as being included in the "exterior member (inside)" in this disclosure.

[0107] For binarization of the "exterior material (outside)", see Figure 14(C).

[0108] In order to enable proper analysis of the image in the image analysis after binarization, it is preferable to acquire the image in advance so that the objects are parallel along the lateral direction (horizontal direction). The range is set so that the entire exterior component (outer component) is included so that all voids in the exterior component (inner component) can be recognized, and the range is also set so that the analysis areas of the "exterior component (outer component)" and "exterior component (inner component)" are the same. For example, to make the area of ​​the "exterior material (outside)" the same as the area of ​​the "exterior material (inside)", the thickness of the exterior material can be measured in advance, and then the analysis range can be appropriately determined by using this as a guide and referring to the length shown in the "imageJ" window when specifying the range.

[0109] By measuring the area of ​​voids in the specified range, the "void ratio (%)" (or void area ratio (%)) can be determined. Specifically, the void ratio (%) may be determined by selecting "Analyzeparticles".

[0110] For example, the size of the void is 0.785 to 400 μm2 It is preferable to determine the porosity within a range of 0.1 to 1.0 (corresponding to a circular diameter of 1 to 20 μm), and the circularity within a range of 0.1 to 1.0. From these values, the cross section of the void can be converted into a circle and the diameter thereof can be determined.

[0111] In the samples shown in Figs. 11 to 14, the porosity of the "exterior member (inside)" was "3.793%", and the porosity of the "exterior member (outside)" was "1.511%".

[0112] By such binarization, the ratio of "porosity of exterior material (inside)" / "porosity of exterior material (outside)" can be obtained. The ratio of "porosity of exterior member (inside)" / "porosity of exterior member (outside)" is, for example, greater than 1.0, preferably 1.1 or more, and more preferably 2 or more and 10 or less. The upper limit of the ratio may be, for example, 10, 9, 8, 7, 6, 5, 4, or 3. For example, in the samples shown in Figs. 11 to 14, the ratio of "porosity of exterior member (inside)" / "porosity of exterior member (outside)" was "2.5".

[0113] In the exterior member (inside), voids may exist in a cross-sectional view at a ratio of, for example, 2% to 20%, preferably 4% to 20%, of the total area of ​​the exterior member (inside) (see FIG. 4).

[0114] In the case where the exterior member (outer) contains voids, such voids may exist in a proportion of, for example, 2% or more and 20% or less, preferably 2% or more and 10% or less, of the total area of ​​the exterior member (outer) in a cross-sectional view (see Figure 4).

[0115] The solid-state battery of the present disclosure will be described in more detail below with reference to examples. Note that the solid-state battery of the present disclosure is not limited to the description of the following examples. EXAMPLES

[0116] Example 1 A solid-state battery 60 according to the embodiment shown in FIG. 7 was fabricated. (i) Preparation of solid-state battery stack The solid-state battery laminate can be manufactured by a printing method such as a screen printing method, a green sheet method using a green sheet, or a combination of these methods. In other words, the solid-state battery laminate may be manufactured in accordance with a conventional manufacturing method for solid-state batteries (therefore, raw materials such as the solid electrolyte, organic binder, solvent, optional additives, positive electrode active material, and negative electrode active material described below may be those used in the manufacture of known solid-state batteries).

[0117] (Laminated block formation) A slurry was prepared by mixing a solid electrolyte, an organic binder, a solvent, and optional additives. The slurry was then molded into a sheet having a thickness of about 10 μm after firing. A paste for a positive electrode was prepared by mixing a positive electrode active material, a solid electrolyte, a conductive additive, an organic binder, a solvent, and any additives. Similarly, a paste for a negative electrode was prepared by mixing a negative electrode active material, a solid electrolyte, a conductive additive, an organic binder, a solvent, and any additives. The positive electrode paste was printed on the sheet, and if necessary, a current collecting layer was printed on it. Similarly, the negative electrode paste was printed on the sheet, and if necessary, a current collecting layer was printed on it. A laminate was obtained by alternately stacking sheets printed with the positive electrode paste and sheets printed with the negative electrode paste. Incidentally, the outermost layer (uppermost layer and / or lowermost layer) of the laminate may be an electrolyte layer, an insulating layer, or an electrode layer.

[0118] (Battery sintered body formation) The laminate was pressure-bonded and integrated, and then cut to a predetermined size. The cut laminate was then degreased and fired to obtain a sintered laminate. The laminate may be degreased and fired before cutting, and then cut.

[0119] (ii) Formation of external terminals For example, as shown in FIG. 7, a silver (Ag) paste was applied to at least the entire left side surface (end surface) and the entire right side surface (end surface) of the solid-state battery laminate, and the paste was heated and cured on a hot plate at 200° C. for 30 minutes to form external terminals (positive terminal 63A, negative terminal 63B) made of silver (Ag).

[0120] (iii) Formation of the Characteristic Part of the Invention (Exterior Member) A paste for a first exterior member and a paste for a second exterior member were prepared as follows. A paste for a first exterior member and a paste for a second exterior member were laminated as green sheets in a two-layer structure around the periphery of the unfired laminate block, except for the side surface on which the external terminals were formed, and the green sheets were fired integrally with the solid-state battery laminate as described above. Paste for the first exterior component A paste containing a glass material, an inorganic filler, an organic binder, and a solvent was prepared. In addition, the ratio of the glass material to the inorganic filler in the paste for the first exterior member was adjusted so that the volume ratio of the glass component to the inorganic filler contained in the first exterior member (61, 61') after firing was 20 / 80. ·Paste for second exterior component A paste containing a glass material, an inorganic filler, an organic binder, and a solvent was prepared. In addition, the ratio of the glass material to the inorganic filler in the paste for the second exterior member was adjusted so that the volume ratio of the glass component / inorganic filler contained in the second exterior member (65, 65') after firing was 50 / 50. In the solid-state battery 60 of Example 1, the gaps (63, 63') included in the first exterior member (61, 61') were formed by gases (O2, CO2, CO, etc.) generated from each layer of the laminate block when integrally sintered with the solid-state battery laminate.

[0121] Example 2 A solid-state battery was fabricated in the same manner as in Example 1, except that no inorganic filler was used in the paste for the first and second exterior members, and the number of layers in the solid-state battery laminate was increased. After the solid-state battery was solidified with resin, it was cut up to the observation surface (see Figure 10). The cut surface was polished with abrasive paper to make it even with the observation surface. Specifically, the solid-state battery was embedded in a cured resin, polished to expose the cross section, and then processed by ion milling to form a smooth cross section for observation. The cross section of the solid-state battery was photographed using a scanning electron microscope (SEM) (see Figure 11 (scale bar: 10 μm)) and binarized using image processing software (“Fiji imageJ” (https: / / imagej.net / Fiji)) (see Figure 14). (Binarization) The electron micrograph scale bars were normalized to the length (10 μm) ("Known Distance") and the unit of measurement (micrometer (μm)) ("Unit of Length") to the distance per pixel ("Distance in pixels"). The distance in pixels was 33 (Pixel aspect ratio = 1.0). The images were divided into "exterior parts (outside)" and "exterior parts (inside)" and binarized (see Figure 12). In the image processing software “Fiji imageJ,” binarization was performed using the default setting of “Default” and “Auto” (see Figs. 13 and 14 ).

[0122] The boundary between the "exterior material (inside)" and the "battery body (or solid-state battery laminate)" is clearly indicated by a white line (pixel count of 1 μm or less) (see FIG. 14(B)). Such a white line is interpreted as being included in the "exterior material (inside)". For binarization of the "exterior material (outside)", see Figure 14(C). The range of image analysis was set so that the analysis areas of the "exterior material (outside)" and "exterior material (inside)" were the same. The void area was measured for the specified range to determine the "void ratio (%)" (or void area ratio (%)) (void area 0.785 to 400 μm 2(corresponding to a circular diameter ("Circularity") of 1-20 μm, with a circularity in the range of 0.1-1.0). The porosity of the "exterior material (inner side)" was "3.793%", and the porosity of the "exterior material (outer side)" was "1.511%". The ratio of "porosity of exterior material (inside)" / "porosity of exterior material (outside)" was "2.5".

[0123] From the above, it was demonstrated that in the solid-state battery produced in Example 2, the "porosity of the exterior member (inside)" was greater than the "porosity of the exterior member (outside)".

[0124] Although the solid-state battery of the present disclosure has been described above with reference to various embodiments and examples, these are merely typical examples. Therefore, it will be easily understood by those skilled in the art that the present disclosure is not limited thereto and various aspects are conceivable.

[0125] (Aspect 1) a solid-state battery laminate including at least one battery constituent unit including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer; external terminals provided on opposing side surfaces of the solid-state battery stack; A solid-state battery further comprising an exterior member covering the solid-state battery stack, wherein a gap is present on an inner side of the exterior member adjacent to the solid-state battery stack (or an interface). (Aspect 2) 2. The solid-state battery of claim 1, wherein the voids are present in a proportion of 2% to 20% of a total area of ​​the exterior member in a cross-sectional view. (Aspect 3) 3. The solid-state battery of claim 1, wherein the void is present in an inner region of the exterior member adjacent to the solid-state battery stack (or an interface). (Aspect 4) 4. The solid-state battery of embodiment 3, wherein the inner region of the exterior member adjacent to the solid-state battery stack (or interface) has a higher porosity than the outer region. (Aspect 5) The solid-state battery according to any one of aspects 1 to 4, wherein the exterior member comprises a glass component, and the voids are present in the glass component. (Aspect 6) 6. The solid-state battery of embodiment 5, wherein the exterior member further comprises an inorganic filler. (Aspect 7) a solid-state battery laminate including at least one battery constituent unit including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer; external terminals provided on opposing side surfaces of the solid-state battery stack; Further, an exterior member that covers the solid-state battery stack is provided, a solid-state battery, wherein the exterior member has a two-layer structure or a structure of two or more layers including a first exterior member and a second exterior member, the first exterior member is provided adjacent to the solid-state battery stack (or an interface), the second exterior member is provided adjacent to the first exterior member on the side opposite to the solid-state battery stack, and a gap exists in the first exterior member. (Aspect 8) 8. The solid-state battery of claim 7, wherein the voids are present in a proportion of 2% to 20% of the total area of ​​the first exterior member in a cross-sectional view. (Aspect 9) The solid-state battery of aspect 7 or 8, wherein the second exterior member also includes voids, and a ratio of a porosity of the first exterior member to a total area of ​​the first exterior member in a cross-sectional view / a porosity of the second exterior member to a total area of ​​the second exterior member is 1.1 or more. (Aspect 10) 8. The solid-state battery of embodiment 7, wherein the exterior member has a structure of two or more layers. (Aspect 11) 8. The solid-state battery of claim 7, wherein the first exterior member and the second exterior member each comprise a glass component, and the voids are present in the glass component of the first exterior member. (Aspect 12) 12. The solid-state battery of claim 5 or 11, wherein the glass component is at least one selected from the group consisting of silica glass, soda-lime glass, potash glass, borate-based glass, borosilicate-based glass, barium borosilicate-based glass, zinc borate-based glass, barium borate-based glass, bismuth borosilicate-based glass, bismuth zinc borate-based glass, bismuth silicate-based glass, phosphate-based glass, aluminophosphate-based glass, and zinc phosphate-based glass. (Aspect 13) 13. The solid-state battery of embodiment 11 or 12, wherein the first exterior member and / or the second exterior member further comprises an inorganic filler. (Aspect 14) 13. The solid-state battery of claim 11 or 12, wherein one of the first exterior member and the second exterior member contains an inorganic filler. (Aspect 15) Water vapor permeability is 1.0×10 -3 g / (m 2 15. The solid-state battery according to any one of aspects 1 to 14, wherein the average lifetime is less than 100 days. (Aspect 16) 16. The solid-state battery according to any one of aspects 1 to 15, wherein the positive electrode layer and the negative electrode layer are layers capable of absorbing and releasing lithium ions. [Industrial Applicability]

[0126] The solid-state battery of the present invention can be utilized in various fields where battery use or power storage can be envisaged. Although merely illustrative, the solid-state battery of the present invention can be used in the electrical, information, and communication fields in which electrical and electronic devices are used (for example, electrical and electronic devices fields or mobile device fields including small electronic devices such as mobile phones, smartphones, notebook computers, digital cameras, activity meters, arm computers, electronic paper, wearable devices, RFID tags, card-type electronic money, and smart watches), household and small industrial applications (for example, power tools, golf carts, household, nursing care, and industrial robots), large industrial applications (for example, forklifts, elevators, and port cranes), transportation systems (for example, hybrid automobiles, electric automobiles, buses, trains, electrically assisted bicycles, and electric motorcycles), power system applications (for example, various power generation, road conditioners, smart grids, and general household installation-type power storage systems), medical applications (medical devices such as earphone hearing aids), pharmaceutical applications (medical management systems), and the IoT field, as well as space and deep sea applications (for example, space probes, submersible research vessels, and the like). [Explanation of symbols]

[0127] 1,101 Positive electrode layer 2,102 Negative electrode layer 3,103 Solid electrolyte layer (or solid electrolyte) 5,105 battery units 10 Solid-state battery stack (or battery body) 11, 21, 51 Exterior materials 12,22,52 Glass components 13,23,33,43,53,63 void 24,54 Inorganic filler 31, 41, 61 First exterior member 32, 42, 62 First glass component 35, 45, 65 Second exterior member 36, 46, 66 Second glass component 44,64 First inorganic filler 47,67 Second inorganic filler 50,60 solid state battery 100 Conventional solid-state batteries 110 Waterproof layer 120 Resin layer 53,63,130 External terminal 53A, 63A, 130A Positive terminal 53B,63B,130B Negative terminal

Claims

1. 1. A solid-state battery comprising: a solid-state battery stack including at least one battery unit including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer; external terminals provided on opposing side surfaces of the solid-state battery stack; a solid-state battery further comprising an exterior member covering the solid-state battery stack and containing a glass component, wherein voids exist in an inner region of the exterior member adjacent to the solid-state battery stack, and the inner region has a larger porosity than an outer region of the exterior member.

2. The solid-state battery according to claim 1 , wherein the voids are present in a proportion of 2% to 20% of the total area of ​​the exterior member in a cross-sectional view.

3. A solid-state battery as described in claim 1 or 2, wherein the void is present in the glass component.

4. The solid-state battery according to claim 3 , wherein the exterior member further comprises an inorganic filler.

5. A solid-state battery according to any one of claims 1 to 4, wherein the glass component is at least one selected from the group consisting of silica glass, soda-lime glass, potash glass, borate glass, borosilicate glass, barium borosilicate glass, zinc borate glass, barium borate glass, bismuth borosilicate glass, bismuth zinc borate glass, bismuth silicate glass, phosphate glass, aluminophosphate glass and zinc phosphate glass.

6. 1. A solid-state battery comprising: a solid-state battery stack including at least one battery unit including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer; external terminals provided on opposing side surfaces of the solid-state battery stack; The solid-state battery stack is covered with an exterior member containing a glass component, a solid-state battery, wherein the exterior member has a two-layer structure or a structure of two or more layers including a first exterior member and a second exterior member, the first exterior member is provided adjacent to the solid-state battery stack, the second exterior member is provided adjacent to the first exterior member on a side opposite to the solid-state battery stack, and a gap exists in the first exterior member.

7. The solid-state battery according to claim 6 , wherein the voids are present in a proportion of 2% to 20% of the total area of ​​the first exterior member in a cross-sectional view.

8. The solid-state battery according to claim 6 or 7, wherein the second exterior member also includes voids, and a ratio of a porosity of the first exterior member to a total area of ​​the first exterior member in a cross-sectional view to a porosity of the second exterior member to a total area of ​​the second exterior member is 1.1 or more.

9. The solid-state battery according to claim 6 , wherein the exterior member has a structure of two or more layers.

10. The solid-state battery according to claim 6 , wherein the first exterior member and the second exterior member each comprise a glass component, and the voids are present in the glass component of the first exterior member.

11. 11. The solid-state battery according to claim 10, wherein the glass component is at least one selected from the group consisting of silica glass, soda-lime glass, potash glass, borate-based glass, borosilicate-based glass, barium borosilicate-based glass, zinc borate-based glass, barium borate-based glass, bismuth borosilicate-based glass, bismuth zinc borate-based glass, bismuth silicate-based glass, phosphate-based glass, aluminophosphate-based glass, and zinc phosphate-based glass.

12. The solid-state battery according to claim 10 or 11, wherein each of the first exterior member and the second exterior member further comprises an inorganic filler.

13. The solid-state battery according to claim 10 , wherein one of the first exterior member and the second exterior member contains an inorganic filler.

14. The exterior member has a water vapor permeability of 1.0 x 10 －３ g / (m ２ The solid-state battery according to any one of claims 1 to 13, wherein the battery life is less than 100 days.

15. The solid-state battery according to any one of claims 1 to 14, wherein the positive electrode layer and the negative electrode layer are layers capable of absorbing and releasing lithium ions.

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