Battery

Abstract

This battery (1000) comprises: a battery element (400) having a laminated structure in which a first electrode layer (100), a solid electrolyte layer (300), and a second electrode layer (200) are laminated in said order; and an insulating member (700) that seals the battery element (400). The insulating member (700) has: a first portion (500) that encloses the battery element (400); and a second portion (600) that is selectively damaged when the internal pressure of the insulating member (700) increases, and serves as a vent path that passes through the first portion (500) from the surface of the battery element (400) through to the outer surface (701) of the insulating member (700).

Description

battery

[0001] The present disclosure relates to batteries.

[0002] Patent Document 1 discloses a stacked battery in which the side surfaces of a battery element formed by the outer edges of a positive electrode layer, a solid electrolyte layer, and a negative electrode layer are coated with a resin.

[0003] Furthermore, Patent Document 2 discloses a battery having a structure in which a battery element is covered with an insulating member.

[0004] JP 2017-220447 A International Publication No. 2022 / 176318

[0005] There is a need in the art for batteries that are highly reliable and safe.

[0006] A battery according to one aspect of the present disclosure includes a battery element having a laminated structure in which a first electrode layer, a solid electrolyte layer, and a second electrode layer are laminated in this order, and an insulating member that seals the battery element, wherein the insulating member has a first portion that encloses the battery element and a second portion that selectively breaks when the internal pressure of the insulating member increases, to become a vent path that passes through the first portion from a surface of the battery element to an outer surface of the insulating member.

[0007] According to the present disclosure, a battery with excellent reliability and safety can be provided.

[0008] FIG. 1 is a cross-sectional view and a plan view showing a schematic configuration of a battery according to an embodiment. FIG. 2 is a cross-sectional view and a plan view showing a schematic configuration of a battery according to a first modified embodiment. FIG. 3 is a cross-sectional view and a plan view showing a schematic configuration of a battery according to a second modified embodiment. FIG. 4 is a cross-sectional view and a plan view showing a schematic configuration of a battery according to a third modified embodiment. FIG. 5 is a cross-sectional view and a plan view showing a schematic configuration of a battery according to a fourth modified embodiment. FIG. 6 is a cross-sectional view and a plan view showing a schematic configuration of a battery according to a fifth modified embodiment. FIG. 7 is a cross-sectional view and a plan view showing a schematic configuration of a battery according to a sixth modified embodiment.

[0009] (Summary of the Present Disclosure) As an overview of the present disclosure, an example of a battery according to the present disclosure will be described below.

[0010] For example, a battery according to a first aspect of the present disclosure includes a battery element having a laminated structure in which a first electrode layer, a solid electrolyte layer, and a second electrode layer are laminated in this order, and an insulating member that seals the battery element, wherein the insulating member has a first portion that encloses the battery element and a second portion that selectively breaks when the internal pressure of the insulating member increases, to become a vent path that passes through the first portion from the surface of the battery element to the outer surface of the insulating member.

[0011] As a result, the insulating member prevents moisture and air from entering the battery element, thereby preventing deterioration of the battery element's characteristics. Furthermore, if the battery element experiences abnormal heat generation or burnout, causing the internal pressure of the insulating member to rise, the second portion of the insulating member selectively breaks, releasing the internal pressure. This prevents the insulating member and battery element from breaking into pieces and scattering to the surrounding area. These effects enable the realization of a battery with excellent reliability and safety.

[0012] Also, for example, a battery according to a second aspect of the present disclosure is the battery according to the first aspect, wherein the second portion contains air bubbles and has a lower density than the first portion.

[0013] This makes it easier for the second portion to be selectively damaged when the internal pressure of the insulating member increases, making it easier for the internal pressure of the insulating member to be released.

[0014] Also, for example, a battery according to a third aspect of the present disclosure is the battery according to the second aspect, wherein the second portion includes a plurality of the bubbles.

[0015] This allows the internal pressure of the insulating member at which the second portion breaks and the airtightness of the insulating member to be adjusted by the number of bubbles, thereby making it possible to obtain a highly reliable and safe battery that meets the intended purpose, taking into account, for example, the application.

[0016] Furthermore, for example, a battery according to a fourth aspect of the present disclosure is the battery according to the second or third aspect, in which the first portion and the second portion contain the same insulating resin.

[0017] This allows the first portion and the second portion to be formed using the same insulating resin depending on whether or not there are bubbles, making it possible to easily form the insulating member.

[0018] Furthermore, for example, a battery according to a fifth aspect of the present disclosure is the battery according to any one of the first to fourth aspects, wherein the first portion includes a first insulating resin.

[0019] This allows the first portion containing the battery element to adhere more closely to the battery element, preventing moisture and atmospheric air from entering the battery element. Furthermore, the first insulating resin can more easily absorb the expansion and contraction of the battery element due to charge / discharge and thermal cycling. This prevents structural defects such as cracks from occurring in the insulating member and the battery element. This results in a highly reliable battery.

[0020] Furthermore, for example, a battery according to a sixth aspect of the present disclosure is the battery according to the fifth aspect, in which the first insulating resin is a thermosetting resin.

[0021] This allows the first portion to be formed by immersing the battery element in a material containing the first insulating resin and thermally curing the material, making it possible to easily form the insulating member.

[0022] Furthermore, for example, a battery according to a seventh aspect of the present disclosure is the battery according to any one of the first to sixth aspects, wherein the second portion is softer than the first portion.

[0023] This makes it easier for the second portion to be selectively damaged when the internal pressure of the insulating member increases, making it easier for the internal pressure of the insulating member to be released.

[0024] Also, for example, a battery according to an eighth aspect of the present disclosure is a battery according to the seventh aspect, wherein the first portion includes a first insulating resin and the second portion includes a second insulating resin that is softer than the first insulating resin.

[0025] This allows the second portion to be more easily brought into close contact with the battery element and the first portion, thereby improving the airtightness of the insulating member.

[0026] Furthermore, for example, a battery according to a ninth aspect of the present disclosure is the battery according to the eighth aspect, in which the second insulating resin is a thermosetting resin.

[0027] This allows the second portion to be formed by thermally curing the material containing the second insulating resin, making it possible to easily form the insulating member.

[0028] Also, for example, a battery according to a tenth aspect of the present disclosure is a battery according to the ninth aspect, wherein the first insulating resin and the second insulating resin are thermosetting resins that harden by cross-linking, and the second insulating resin has a lower degree of cross-linking than the first insulating resin.

[0029] This allows the second insulating resin to be made softer than the first insulating resin simply by adjusting the degree of cross-linking by the curing temperature or the like, making it possible to easily form the insulating member.

[0030] Furthermore, for example, a battery according to an eleventh aspect of the present disclosure is the battery according to any one of the first to tenth aspects, wherein the second portion includes thermally expandable particles.

[0031] This allows the heat-expanding particles to expand when the battery element generates heat, making the second portion more susceptible to damage, thereby preventing damage and fire from spreading to the periphery of the battery and achieving a highly reliable battery.

[0032] Furthermore, for example, a battery according to a twelfth aspect of the present disclosure is the battery according to the eleventh aspect, in which the thermally expandable particles are expandable particles.

[0033] This makes the expandable particles expand when the battery element generates heat, making the second portion more susceptible to breakage.

[0034] Furthermore, for example, a battery according to a thirteenth aspect of the present disclosure is the battery according to the twelfth aspect, wherein the expandable particles are formed of microcapsules filled with a volatile material.

[0035] This makes it possible to control the expansion rate and expansion temperature of the expandable particles by adjusting the type and content of the volatile material.

[0036] Furthermore, for example, a battery according to a fourteenth aspect of the present disclosure is the battery according to the twelfth or thirteenth aspect, wherein the expansion starting temperature of the expandable particles is 150°C or higher and 250°C or lower.

[0037] This allows the expandable particles to expand when the battery element generates abnormal heat, and allows a vent path to be formed before the battery element and insulating member reach excessively high temperatures.

[0038] Furthermore, for example, a battery according to a fifteenth aspect of the present disclosure is a battery according to any one of the first to fourteenth aspects, wherein the second portion is positioned to include a position where the distance between the battery element and the outer surface of the insulating member is shortest.

[0039] This reduces the pressure at which the second portion becomes a vent path.

[0040] Furthermore, for example, a battery according to a sixteenth aspect of the present disclosure is a battery according to any one of the first to fourteenth aspects, wherein the second portion is positioned to include a position where the distance between the battery element and the outer surface of the insulating member is longest.

[0041] This allows the pressure at which the second portion becomes a vent path to be increased.

[0042] Furthermore, for example, a battery according to a seventeenth aspect of the present disclosure is the battery according to any one of the first to sixteenth aspects, wherein the second portion is bent.

[0043] This allows the internal pressure of the insulating member at which the second portion breaks to be adjusted by adjusting the number of bent locations in the second portion and the manner in which the second portion is bent, and also allows the position on the outer surface of the insulating member at which the internal pressure is released to be adjusted.

[0044] Furthermore, for example, a battery according to an eighteenth aspect of the present disclosure is the battery according to any one of the first to seventeenth aspects, wherein the second portion is branched.

[0045] This makes it possible to adjust the internal pressure of the insulating member at which the second portion breaks by adjusting the number of branches in the second portion and the branching method, and also to adjust the position on the outer surface of the insulating member at which the internal pressure is released.

[0046] Also, for example, a battery according to a 19th aspect of the present disclosure is a battery according to any one of the 1st to 18th aspects, and includes a lead terminal connected to the first electrode layer or the second electrode layer and extending through the insulating member to the outside of the insulating member, and the second portion is arranged along the lead terminal.

[0047] This allows the internal pressure of the insulating member to be released along the rigid wall surface of the lead terminal, making it possible to form a vent path in the insulating member at a precise position.

[0048] Furthermore, for example, a battery according to a twentieth aspect of the present disclosure is the battery according to any one of the first to nineteenth aspects, wherein the lead terminal has a bent portion or a step within the insulating member.

[0049] This allows the pressure at which the second portion becomes a vent path to be adjusted by adjusting the degree and position of the bend or step of the lead terminal.

[0050] Furthermore, for example, a battery according to a twenty-first aspect of the present disclosure is the battery according to the nineteenth or twentieth aspect, in which the second portion includes a silicone resin.

[0051] This improves the adhesion between the second portion and the lead terminal, thereby preventing moisture and air from penetrating into the insulating member through the interface between the second portion and the lead terminal, thereby preventing deterioration of the battery element.

[0052] Furthermore, for example, a battery according to a twenty-second aspect of the present disclosure is the battery according to any one of the nineteenth to twenty-first aspects, wherein the second portion includes a silane coupling agent.

[0053] This improves the adhesion between the second portion and the lead terminal, thereby preventing moisture and air from penetrating into the insulating member through the interface between the second portion and the lead terminal, thereby preventing deterioration of the battery element.

[0054] Hereinafter, the embodiments will be specifically described with reference to the drawings.

[0055] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement positions, and connection configurations shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components that are not recited in independent claims are described as optional components.

[0056] Furthermore, in this specification, terms indicating the relationship between elements, such as parallelism, terms indicating the shape of elements, such as rectangle, and numerical ranges are not expressions that only express a strict meaning, but are expressions that also include a substantially equivalent range, for example, a difference of about a few percent.

[0057] In addition, the drawings are not necessarily strict illustrations, and the same reference numerals are used to designate substantially the same components in the drawings, and redundant explanations are omitted or simplified.

[0058] In this specification and the drawings, the x-axis, y-axis, and z-axis represent the three axes of a three-dimensional Cartesian coordinate system. In the following embodiments, the z-axis direction is the stacking direction of the battery elements. When the battery element has a rectangular shape in a plan view, the x-axis and y-axis are directions parallel to a first side of the rectangle and a second side perpendicular to the first side, respectively.

[0059] In this specification, the "stacking direction" corresponds to the direction perpendicular to the main surface of each layer of the battery element. The "main surface" is the surface of each component with the largest area.

[0060] In addition, in this specification, the "inside" and "outside" of the terms "inside" and "outside" refer to the center side of the battery and the outer edge side of the battery.

[0061] Furthermore, in this specification, the terms "upper" and "lower" in the battery configuration do not refer to the upper direction (vertically upper) and lower direction (vertically lower) in absolute spatial recognition, but are used as terms defined by a relative positional relationship based on the stacking order in the stacking configuration. Furthermore, the terms "upper" and "lower" are used not only when two components are arranged with a gap between them and another component is present between them, but also when two components are arranged closely together and the two components are in contact. In the following description, the negative side of the z axis is referred to as "lower" or "lower side," and the positive side of the z axis is referred to as "upper" or "upper side."

[0062] (Embodiment) [Battery Overview] First, an overview of the battery according to this embodiment will be described.

[0063] FIG. 1 is a cross-sectional view and a plan view showing a schematic configuration of a battery 1000 according to this embodiment. Specifically, FIG. 1(a) is a cross-sectional view of the battery 1000 according to this embodiment, and FIG. 1(b) is a plan view of the battery 1000 as seen from below in the z-axis direction. FIG. 1(a) shows a cross section taken along line Ia-Ia in FIG. 1(b). In addition, FIG. 1(b) shows the outlines of the battery element 400 and the second portion 600, which are not actually visible, in dashed lines.

[0064] 1 , the battery 1000 includes a battery element 400 including a first electrode layer 100, a solid electrolyte layer 300, and a second electrode layer 200, and an insulating member 700. The insulating member 700 seals the battery element 400. The first electrode layer 100 includes a first current collector 110 and a first active material layer 120. The second electrode layer 200 includes a second current collector 210 and a second active material layer 220. The battery 1000 further includes a lead terminal 800a electrically connected to the first electrode layer 100 and a lead terminal 800b electrically connected to the second electrode layer 200. The battery 1000 is, for example, an all-solid-state battery.

[0065] 1 , the insulating member 700 exposes portions of the lead terminals 800 a and 800 b, and encloses and seals the battery element 400 and the remaining portions of the lead terminals 800 a and 800 b. The portions of the lead terminals 800 a and 800 b are pulled out and exposed from the insulating member 700, and are connected to an external circuit, for example, as mounting terminals.

[0066] The insulating member 700 has a first portion 500 that forms the general shape of the insulating member 700 and a second portion 600. The second portion 600 is in contact with a portion of the battery element 400. When the internal pressure of the insulating member 700 increases, the second portion 600 selectively breaks, forming a vent path that penetrates the first portion 500. The insulating member 700 seals the battery element 400, thereby suppressing deterioration of the battery element 400's characteristics due to moisture, atmospheric air, and the like. Furthermore, since the insulating member 700 has the second portion 600, when the internal pressure of the insulating member 700 increases, the second portion 600 selectively breaks, releasing the internal pressure. This prevents the insulating member 700 and the battery element 400 from shattering and scattering around. This improves the reliability and safety of the battery 1000.

[0067] Each component of the battery 1000 will be described in detail below with reference to FIG.

[0068] [Battery Element] The battery element 400 has a layered structure in which a first electrode layer 100, a solid electrolyte layer 300, and a second electrode layer 200 are layered in this order. The planar shape of the battery element 400 is, for example, rectangular. That is, the general shape of the battery 1000 is a flattened rectangular parallelepiped. Here, "flat" means that the thickness (i.e., the length in the z-axis direction) is shorter than the length of each side of the main surface (i.e., the length in each of the x-axis and y-axis directions) or the maximum width. The planar shape of the battery element 400 may be other polygonal shapes such as a square, hexagon, or octagon, or may be a circular or elliptical shape. Note that in the drawings relating to this specification, in cross-sectional views showing the configuration of the battery, the thickness of each layer is exaggerated to make the layered structure of the battery element 400 easier to understand.

[0069] The battery element 400 includes four side surfaces 401 , 402 , 403 and 404 and two main surfaces 405 and 406 .

[0070] The side surfaces 401 and 402 are back-to-back and parallel to each other. The side surfaces 403 and 404 are back-to-back and parallel to each other. The side surfaces 401, 402, 403, and 404 stand upright from each edge of the main surfaces 405 and 406 in a direction intersecting the main surfaces 405 and 406, specifically perpendicular to the main surfaces 405 and 406. The side surfaces 401, 402, 403, and 404 are surfaces connecting the main surfaces 405 and 406. The side surfaces 401, 402, 403, and 404 are, for example, parallel to the stacking direction of the battery element 400. The main surfaces 405 and 406 are back-to-back and parallel to each other. In the example shown in FIG. 1 , the side surfaces 401, 402, 403, and 404 include the side surfaces of the first electrode layer 100, the solid electrolyte layer 300, and the second electrode layer 200, respectively. Furthermore, the main surface 405 is the upper surface of the battery element 400 , and the main surface 406 is the lower surface of the battery element 400 .

[0071] 1 , a portion of the side surface 401 of the battery element 400 is in contact with the second portion 600. Note that at least a portion of the side surfaces 402, 403, and 404 other than the side surface 401 of the battery element 400 and the main surfaces 405 and 406 may be in contact with the second portion 600.

[0072] The first electrode layer 100 includes a first current collector 110 and a first active material layer 120. The second electrode layer 200 includes a second current collector 210 and a second active material layer 220. The first electrode layer 100 and the second electrode layer 200 face each other with the solid electrolyte layer 300 sandwiched therebetween and are in contact with the solid electrolyte layer 300. The facing distance between the first electrode layer 100 and the second electrode layer 200 is, for example, 10 μm or more and 500 μm or less.

[0073] 1 , the first active material layer 120, the second active material layer 220, the first current collector 110, the second current collector 210, and the solid electrolyte layer 300 are all the same size and have the same contour shape in a plan view, but this is not limited to this. For example, the first active material layer 120 and the second active material layer 220 may have different contour shapes. This makes it possible to determine the polarity (positive / negative poles) of the battery 1000 and correct its position by, for example, observing the size relationship between the first active material layer 120 and the second active material layer 220 from the side (e.g., by image recognition), thereby reducing polarity errors during production.

[0074] The first electrode layer 100 and the second electrode layer 200 are electrodes of opposite polarity. In the present embodiment, one of the first electrode layer 100 and the second electrode layer 200 is a positive electrode layer including a positive electrode active material layer and a positive electrode current collector, and the other is a negative electrode layer including a negative electrode active material layer and a negative electrode current collector. Hereinafter, a case will be described as an example in which the first electrode layer 100 is a positive electrode layer including a first active material layer 120 and a first current collector 110 as a positive electrode active material layer and a positive electrode current collector, and the second electrode layer 200 is a negative electrode layer including a second active material layer 220 and a second current collector 210 as a negative electrode active material layer and a negative electrode current collector.

[0075] The first electrode layer 100 may be a negative electrode layer, and the second electrode layer 200 may be a positive electrode layer. Specifically, the first current collector 110 may be a negative electrode current collector, the first active material layer 120 may be a negative electrode active material layer, the second current collector 210 may be a positive electrode current collector, and the second active material layer 220 may be a positive electrode active material layer.

[0076] The first active material layer 120 is in contact with one main surface of the first current collector 110. The first current collector 110 may include a connection layer, which is a layer containing a conductive material, provided in a portion in contact with the first active material layer 120. A lead terminal 800a is connected to the other main surface of the first current collector 110. The other main surface of the first current collector 110 constitutes the main surface 405 of the battery element 400.

[0077] The second active material layer 220 is in contact with one main surface of the second current collector 210. The second current collector 210 may include a connection layer, which is a layer containing a conductive material, provided in a portion in contact with the second active material layer 220. A lead terminal 800b is connected to the other main surface of the second current collector 210. The other main surface of the second current collector 210 constitutes the main surface 406 of the battery element 400.

[0078] The first current collector 110 and the second current collector 210 may each be formed of a conductive material, and are not particularly limited. The first current collector 110 and the second current collector 210 may be, for example, a foil, plate, or mesh-like material made of stainless steel, nickel (Ni), aluminum (Al), iron (Fe), titanium (Ti), copper (Cu), palladium (Pd), gold (Au), platinum (Pt), or an alloy of two or more of these metals. The materials for the first current collector 110 and the second current collector 210 may be appropriately selected based on the characteristics of the material, such as the fact that they do not melt or decompose during the manufacturing process, the operating temperature, or the operating pressure, and the operating potential and conductivity of the battery applied to the first current collector 110 and the second current collector 210. The materials for the first current collector 110 and the second current collector 210 may also be selected based on the required tensile strength or heat resistance. The first current collector 110 and the second current collector 210 may be made of high-strength electrolytic copper foil or a clad material in which foils of different metals are laminated.

[0079] The thickness of each of the first current collector 110 and the second current collector 210 is, for example, 10 μm or more and 100 μm or less, but is not limited to this. At least one surface of the first current collector 110 and the second current collector 210 may be processed to have an uneven, rough surface in order to improve adhesion with the first active material layer 120 or the second active material layer 220. Furthermore, an adhesive component such as an organic binder may be applied to at least one surface of the first current collector 110 and the second current collector 210. This strengthens the bonding at the interfaces between the first current collector 110 and the second current collector 210 and other layers, thereby improving the mechanical and thermal reliability, as well as the cycle characteristics, of the battery 1000.

[0080] The first active material layer 120 is disposed between the first current collector 110 and the solid electrolyte layer 300. One main surface of the first active material layer 120 is in contact with the first current collector 110, and the other main surface is in contact with the solid electrolyte layer 300. In the present embodiment, the first active material layer 120 covers the entire one main surface of the first current collector 110.

[0081] In this embodiment, the first active material layer 120 is a positive electrode active material layer, and therefore contains at least a positive electrode active material. In other words, the first active material layer 120 is a layer mainly composed of a positive electrode material such as a positive electrode active material. The positive electrode active material is a material in which metal ions such as lithium (Li) or magnesium (Mg) are inserted or extracted into or from the crystal structure at a potential higher than that of the negative electrode, and oxidation or reduction occurs accordingly. The type of positive electrode active material can be appropriately selected depending on the type of battery, and known positive electrode active materials can be used. Examples of the positive electrode active material include compounds containing lithium and a transition metal element, such as oxides containing lithium and a transition metal element and phosphate compounds containing lithium and a transition metal element. Examples of oxides containing lithium and a transition metal element include LiNi ｘ M １－ｘ O ２ (wherein M is at least one element selected from Co, Al, Mn, V, Cr, Mg, Ca, Ti, Zr, Nb, Mo, and W, and x is 0<x≦1), lithium nickel composite oxides such as lithium cobalt oxide (LiCoO ２ ), lithium nickel oxide (LiNiO ２ ), lithium manganese oxide (LiMn ２ O ４ ), and lithium manganese oxide (LiMn) with a spinel structure. ２ O ４ , Li ２ MnO ３ , LiMO ２ As a phosphate compound containing lithium and a transition metal element, for example, lithium iron phosphate (LiFePO ) having an olivine structure is used. ４ ) and the like are used as the positive electrode active material. ２In this case, the positive electrode active material particles may contain sulfides such as lithium niobate (LiNbO ３ ) or the like may be coated or added to the cathode active material. The cathode active material may be a single material, or a combination of two or more materials.

[0082] As described above, the first active material layer 120, which is a positive electrode active material layer, only needs to contain at least a positive electrode active material. The first active material layer 120 may be a mixture layer composed of a mixture of a positive electrode active material and other additive materials. Examples of the additive materials that can be used include solid electrolytes such as inorganic solid electrolytes or sulfide-based solid electrolytes, conductive additives such as acetylene black, and adhesive binders such as polyethylene oxide or polyvinylidene fluoride. By mixing the positive electrode active material and other additive materials, such as a solid electrolyte, in a predetermined ratio, the first active material layer 120 can improve both ionic conductivity and electronic conductivity within the first active material layer 120.

[0083] The thickness of the first active material layer 120 is, for example, not less than 5 μm and not more than 300 μm, but is not limited to this.

[0084] The second active material layer 220 is disposed between the second current collector 210 and the solid electrolyte layer 300. The second active material layer 220 is in contact with the second current collector 210 on one main surface and in contact with the solid electrolyte layer 300 on the other main surface. In the present embodiment, the second active material layer 220 covers the entire one main surface of the second current collector 210.

[0085] In this embodiment, the second active material layer 220 is an anode active material layer and therefore includes at least an anode active material. That is, the second active material layer 220 is a layer mainly composed of an anode material such as an anode active material. An anode active material is a material in which metal ions such as lithium (Li) ions or magnesium (Mg) ions are inserted or extracted into or from the crystalline structure at a potential lower than that of the positive electrode, and oxidation or reduction occurs accordingly. The type of anode active material can be appropriately selected depending on the type of battery 1000, and known anode active materials can be used.

[0086] Examples of the negative electrode active material include carbon materials such as natural graphite, artificial graphite, graphite carbon fiber, and resin-baked carbon, and alloy materials that are mixed with a solid electrolyte. Examples of alloy materials include LiAl, LiZn, and Li ３ Bi, Li ３ Cd, Li ３ Sb, Li ４ Si, Li ４．４ Pb, Li ４．４ Sn, Li ０．１７ C, LiC ６ Lithium alloys such as lithium titanate (Li ４ Ti ５ O １２ oxides of lithium and transition metal elements such as zinc oxide (ZnO) and silicon oxide (SiO ｘ For the negative electrode active material, only one of these materials may be used, or two or more of these materials may be used in combination.

[0087] As described above, the second active material layer 220, which is the negative electrode active material layer, only needs to contain at least a negative electrode active material. The second active material layer 220 may be a mixture layer composed of a mixture of a negative electrode active material and other additive materials. Examples of other additive materials that can be used include solid electrolytes such as inorganic solid electrolytes or sulfide-based solid electrolytes, conductive additives such as acetylene black, and adhesive binders such as polyethylene oxide or polyvinylidene fluoride. By mixing the negative electrode active material and other additive materials, such as a solid electrolyte, in a predetermined ratio, the second active material layer 220 can improve both ionic conductivity and electronic conductivity within the second active material layer 220.

[0088] The thickness of the second active material layer 220 is, for example, not less than 5 μm and not more than 300 μm, but is not limited to this.

[0089] The solid electrolyte layer 300 is disposed between the first active material layer 120 and the second active material layer 220, and is in contact with both the first active material layer 120 and the second active material layer 220. The solid electrolyte layer 300 includes at least a solid electrolyte.

[0090] The solid electrolyte may be any known solid electrolyte for batteries that has ion conductivity. For example, a solid electrolyte that conducts metal ions, such as lithium ions or magnesium ions, may be used. The type of solid electrolyte may be selected appropriately depending on the type of ions to be conducted. The solid electrolyte layer 300 may be softer than the first active material layer 120 and the second active material layer 220. The softness of the solid electrolyte layer 300 relative to the first active material layer 120 and the second active material layer 220 can be confirmed, for example, by evaluating a cross section flattened by ion milling or other means using a micro-Vickers spectroscope. For example, when an indenter is pressed against the cross section with the same pressure, the larger the size of the indentation mark left behind, the softer the layer is determined to be.

[0091] As the solid electrolyte, for example, an inorganic solid electrolyte such as a sulfide-based solid electrolyte or an oxide-based solid electrolyte can be used. As the sulfide-based solid electrolyte, for example, Li ２ S-P ２ S ５ system, Li ２ S-SiS ２ system, Li ２ S-B ２ S ３ system, Li ２ S-GeS ２ system, Li ２ S-SiS ２ -LiI system, Li ２ S-SiS ２ -Li ３ P.O. ４ system, Li ２ S-Ge ２ S ２ system, Li ２ S-GeS ２ -P ２ S ５ system, or Li ２ S-GeS ２ Lithium-containing sulfides such as ZnS-based can be used. ２ O—SiO ２ Or Li ２ O—SiO ２ -P ２ O５ Lithium-containing metal oxides such as Li ｘ P ｙ O １－ｚ N ｚ lithium-containing metal nitrides such as lithium phosphate (Li ３ P.O. ４ ), or a lithium-containing transition metal oxide such as lithium titanium oxide, etc., can be used. As the solid electrolyte, only one of these materials may be used, or two or more of these materials may be used in combination. In the present embodiment, the solid electrolyte layer 300 includes, as an example, a solid electrolyte having lithium ion conductivity.

[0092] The solid electrolyte layer 300 may contain, in addition to the above solid electrolyte material, a bonding binder such as polyethylene oxide or polyvinylidene fluoride.

[0093] The thickness of the solid electrolyte layer 300 is, for example, not less than 5 μm and not more than 500 μm, but is not limited to this.

[0094] The solid electrolyte layer 300 may be formed as an aggregate of solid electrolyte particles, or may be formed as a sintered structure of the solid electrolyte.

[0095] [Insulating Member] The battery element 400 is embedded in the insulating member 700, and the insulating member 700 seals the battery element 400. Because the battery element 400 is embedded and sealed in the insulating member 700, the reliability of the battery 1000 can be improved in various respects, such as impact resistance, mechanical strength, short-circuit suppression, and moisture resistance. The insulating member 700 has, for example, an outer shape corresponding to the shape of the battery element 400. In the example shown in FIG. 1 , the outer shape of the insulating member 700 is a rectangular parallelepiped similar to that of the battery element 400. The insulating member 700 is, for example, a molded resin member formed using a mold with the battery element 400 embedded in its center. Alternatively, the insulating member 700 may be formed by applying a resin material so as to cover the entire battery element 400. Because the insulating member 700 does not have a structure such as a laminated film, for example, it is highly effective in improving the reliability of the battery 1000 as described above.

[0096] The insulating member 700 has a first portion 500 that encloses the battery element 400, and a second portion 600 that is disposed so as to penetrate the first portion 500 from the surface of the battery element 400 to an outer surface 701 of the insulating member 700. In the example shown in Fig. 1 , the outer surface 701 includes a plurality of flat surfaces that face and are parallel to the side surfaces 401, 402, 403, and 404 and the main surfaces 405 and 406 of the battery element 400, respectively.

[0097] The first portion 500 covers all of the surfaces of the battery element 400 (in this embodiment, the side surfaces 401, 402, 403, and 404 and the main surfaces 405 and 406) that are not in contact with the second portion 600. The first portion 500 is in contact with the portion of the side surface 401 that is not in contact with the second portion 600, as well as the entire surfaces of the side surfaces 402, 403, and 404. By having the first portion 500 cover most of the surface of the battery element 400 in this way, the effect of the insulating member 700 in improving the reliability of the battery 1000 can be enhanced.

[0098] When the internal pressure of the insulating member 700 increases, the second portion 600 selectively breaks, forming a vent path that penetrates the first portion 500 from the surface of the battery element 400 to the outer surface 701 of the insulating member 700. In other words, when the internal pressure of the insulating member 700 increases, the second portion 600 breaks before the first portion 500 does, and releases the internal pressure of the insulating member 700 to the outside of the insulating member 700.

[0099] The second portion 600 is disposed to connect the battery element 400 contained in the first portion 500 to the outer surface 701 of the insulating member 700. When the internal pressure of the insulating member 700 increases, the second portion 600 selectively breaks, forming a vent path that penetrates the first portion 500 from the surface of the battery element 400 to the outer surface 701 of the insulating member 700. The second portion 600 is surrounded by the first portion 500, and is covered by the first portion 500 except for a portion that contacts the battery element 400 and a portion that constitutes part of the outer surface 701 of the insulating member 700. There is no step between the first portion 500 and the second portion 600 on the outer surface 701 of the insulating member 700, and the outer surface 701 is a flat surface. The second portion 600 extends straight from the surface of the battery element 400 toward the outer surface 701 of the insulating member 700. The second portion 600 may be curved.

[0100] In addition, the second portion 600 is disposed so as to include a position where the distance between the battery element 400 and the outer surface 701 of the insulating member 700 is shortest. In the example shown in Fig. 7, the second portion 600 extends from the side surface 401 toward the portion of the outer surface 701 of the insulating member 700 that is closest to the side surface 401. This makes it possible to reduce the pressure at which a vent path is formed in the insulating member 700.

[0101] The second portion 600 includes a plurality of bubbles 601 and has a lower density than the first portion 500. Here, "density" does not refer to the true density of the material of the first portion 500 and the second portion 600, but rather refers to the apparent density including the bubbles 601. The second portion 600 is filled with an insulating material except for the plurality of bubbles 601. The bubbles 601 are closed bubbles, and even if the second portion 600 includes a plurality of bubbles 601, the insulating member 700 can still seal the battery element 400. Some of the plurality of bubbles 601 may be interconnected. The bubbles 601 are spherical. The diameter of the bubbles 601 is, for example, 0.1 μm or more and 10 μm or less when converted into a perfect sphere. In this way, because the second portion 600 contains the bubbles 601 and has a lower density than the first portion 500, when the internal pressure of the insulating member 700 increases, the second portion 600 is selectively damaged by the internal pressure, a vent path is formed in the insulating member 700, and the internal pressure is released. In other words, when the internal pressure of the insulating member 700 increases and exceeds a predetermined pressure, the second portion 600 is damaged preferentially over the first portion 500, and a vent path is formed that penetrates the insulating member 700 between the battery element 400 and the outer surface 701 of the insulating member 700. Here, the internal pressure of the insulating member 700 refers to the pressure in the region inside the insulating member 700 where the battery element 400 is disposed.

[0102] In the battery 1000 shown in FIG. 1 , the second portion 600 is in contact with a portion of the side surface 401 of the battery element 400. Specifically, the second portion 600 is in contact with only a portion of the side surface 401 of the battery element 400 among the surfaces of the battery element 400. Because the second portion 600 is in contact with the side surface 401 of the battery element 400, a vent path can be formed with good responsiveness in response to an increase in internal pressure due to heat generation or the like in the side surface portion of the battery element 400, which is prone to short circuits due to structural defects, deformation, or the like. Furthermore, the second portion 600 is in contact with the first electrode layer 100, which includes a positive electrode active material layer that is particularly prone to heat generation within the battery element 400, at the side surface 401.

[0103] The position where the second portion 600 contacts the battery element 400 is not particularly limited, and the second portion 600 may contact the entire side surface 401 of the battery element 400, or may contact a side surface of the battery element 400 other than the side surface 401, or may be formed at any location that is likely to generate heat. The second portion 600 may also contact the main surface 405 or 406 of the battery element 400. In this case, the second portion 600 may contact the central region of the main surface 405 or 406 that is likely to generate heat during charge and discharge operations. By having the second portion 600 contact the main surface 405 or 406, a vent path can be formed with good responsiveness in response to an increase in internal pressure due to abnormal heat generation in the active material layer that is likely to generate heat during charge and discharge operations.

[0104] The second portion 600 may also be in contact with a portion of the ridge line, which is the intersection between the side surface and the main surface of the battery element 400. For example, the second portion 600 may be in continuous contact from the side surface 401 to the main surface 405 of the battery element 400. In this case, different insulating materials may be used depending on the location where the second portion 600 contacts, such as the side surface, the main surface, or the ridge line, and any insulating material may be used for each location in terms of the heat generation temperature and impact resistance of the battery element 400. In this way, by having the second portion 600 in contact with the main surface or the ridge line of the battery element 400, a vent path can be formed in any location of the battery element 400 that is prone to heat generation or burnout.

[0105] In the example shown in FIG. 1, the insulating material is in contact with the battery element 400 in the second portion 600 , but the bubbles 601 may be in contact with the battery element 400 .

[0106] The insulating member 700 is not particularly limited as long as it is formed of an insulating material having insulating properties. In the present embodiment, the first portion 500 and the second portion 600 of the insulating member 700 are formed of, for example, the same insulating material. The first portion 500 and the second portion 600 contain, for example, the same insulating resin. This facilitates the formation of the insulating member 700. Furthermore, when the first active material layer 120, the second active material layer 220, and the solid electrolyte layer 300 are formed of powder materials, the first portion 500 and the second portion 600 can penetrate into the fine irregularities formed by the powder material on the side surfaces of the first active material layer 120, the second active material layer 220, and the solid electrolyte layer 300, thereby improving the adhesion between the first portion 500 and the second portion 600 and the battery element 400.

[0107] Examples of insulating resins include epoxy resin, silicone resin, acrylic resin, and fluororesin. The insulating resin may be a thermosetting resin. The thermosetting resin is a resin that hardens by crosslinking, such as epoxy resin, silicone resin, or acrylic resin.

[0108] The first portion 500 and the second portion 600 may also contain an insulating oxide such as aluminum oxide, zirconium oxide, or titanium oxide. The first portion 500 and the second portion 600 may be formed from a mixed material of an insulating resin and an insulating oxide. The first portion 500 and the second portion 600 may also have a laminated structure of multiple layers that differ in at least one of composition and shape. Examples of the layer shape include a foil, a plate, and a mesh. The laminated structure may include, for example, a layer made of a soft resin material on the outer surface 701 side and a layer made of a hard plate-like insulating oxide on the battery element 400 side.

[0109] The insulating material of the first portion 500 and the second portion 600 may be appropriately selected in consideration of the fact that it does not melt or decompose during normal manufacturing processes, at normal temperatures or under normal pressures, and in consideration of the operating potential and conductivity of the battery element 400 applied to the first portion 500 and the second portion 600, and the stress associated with the expansion and contraction of the battery element 400. The insulating material of the first portion 500 and the second portion 600 may also be selected in consideration of the required tensile strength or heat resistance.

[0110] [Lead Terminals] The lead terminals 800a and 800b electrically connect an external circuit and the battery element 400. The lead terminals 800a and 800b are foil- or plate-shaped conductors made of metal such as nickel, stainless steel, aluminum, iron, or copper. In the example shown in Fig. 1, the lead terminals 800a and 800b have a uniform width and thickness.

[0111] The lead terminal 800a is connected to the first electrode layer 100 and is drawn out to the outside of the insulating member 700 through the insulating member 700. The lead terminal 800a is connected to the first current collector 110 of the first electrode layer 100 at the main surface 405. The lead terminal 800a is not connected to the battery element 400 at any location other than the main surface 405, and is not in contact with the side surfaces of the battery element 400. The lead terminal 800b is connected to the second electrode layer 200 and is drawn out to the outside of the insulating member 700 through the insulating member 700. The lead terminal 800b is connected to the second current collector 210 of the second electrode layer 200 at the main surface 406. The lead terminal 800b is not connected to the battery element 400 at any location other than the main surface 406, and is not in contact with the side surfaces of the battery element 400. The lead terminals 800a and 800b are connected to the first current collector 110 and the second current collector 210, respectively, by, for example, a conductive adhesive or solder (not shown). The lead terminals 800a and 800b may be welded to the first current collector 110 and the second current collector 210, respectively.

[0112] Lead terminal 800a has bent portions 801a and 802a that are bent within insulating member 700. Lead terminal 800a, connected to main surface 405, extends in a direction along main surface 405 so as to protrude outward from side surface 402, then bends at bent portion 801a to face side surface 402 and extend in a direction along side surface 402, and then bends at bent portion 802a to extend in a direction away from side surface 402, and is drawn out from the side surface of insulating member 700. The portion of lead terminal 800a between bent portions 801a and 802a faces side surface 402 via first portion 500. The bending of lead terminal 800a lengthens the intrusion path for moisture, air, and the like when they infiltrate insulating member 700, thereby suppressing the intrusion of moisture and air into insulating member 700. The portion of the lead terminal 800a that is pulled out from the insulating member 700 extends downward along the side of the insulating member 700, then wraps around to the underside of the insulating member 700, and the end of the lead terminal 800a forms a connection terminal portion with a mounting substrate, etc.

[0113] Lead terminal 800b has bent portions 801b and 802b that are bent within insulating member 700. Lead terminal 800b connected to main surface 406 extends in a direction along main surface 406 so as to protrude outward from side surface 401, then bends at bent portion 801b to extend in a direction along side surface 401 facing side surface 401, and further bends at bent portion 802b to extend in a direction away from side surface 401, and is drawn out from the side surface of insulating member 700. A portion of lead terminal 800b between bent portions 801b and 802b faces side surface 401 via first portion 500. The bending of lead terminal 800b lengthens the intrusion path for moisture, air, and the like when they infiltrate insulating member 700, thereby suppressing the intrusion of moisture and air into insulating member 700. The portion of the lead terminal 800b that is pulled out from the insulating member 700 extends downward along the side of the insulating member 700, then wraps around to the underside of the insulating member 700, and the end of the lead terminal 800b forms a connection terminal portion with a mounting substrate, etc.

[0114] Although lead terminals 800a and 800b have two bent portions within insulating member 700, the number of bent portions that lead terminals 800a and 800b have is not particularly limited and may be one, or may be three or more. Also, lead terminals 800a and 800b do not have to have any bent portions within insulating member 700. Also, although the connection terminal portions of lead terminals 800a and 800b are both provided on the lower surface of insulating member 700, at least one of them may be provided on the upper surface or side surface of insulating member 700.

[0115] [Effects, etc.] According to the above configuration, the battery element 400 is sealed with the insulating member 700 having the second portion 600, thereby protecting the battery element 400. Furthermore, if abnormal heat generation or burnout occurs in the battery element 400 and the internal pressure of the insulating member 700 increases, the second portion 600 selectively breaks and becomes a vent path, allowing the internal pressure to be released. This prevents the insulating member 700 and the battery element 400 from breaking into pieces and scattering to the surrounding area. Therefore, for example, damage and fire spreading around the battery 1000 can be prevented. These effects enable a highly reliable and safe battery to be realized.

[0116] When the configuration of the battery 1000 according to this embodiment is compared with the configurations of the batteries described in Patent Documents 1 and 2, the following differences are found.

[0117] Patent Document 1 discloses a stacked battery in which the side surfaces formed by the outer edges of the positive electrode layer, solid electrolyte layer, and negative electrode layer are coated with resin. However, the battery does not have a structure to release pressure if the internal pressure within the coated resin increases. That is, the battery in Patent Document 1 differs from the battery 1000 in that the resin coating the battery element does not have a structure that serves as a vent path. With such a configuration, there is a high possibility that the insulating member and battery element will break into pieces and scatter into the surrounding area. Therefore, if the battery generates abnormal heat, there is a possibility that the area around the battery will be damaged and catch fire.

[0118] Furthermore, Patent Document 2 discloses a battery having a structure in which a battery element is covered with an insulating member. However, in the battery disclosed in Patent Document 2, the insulating member covering the battery element does not have a structure that serves as a vent path.

[0119] In contrast to these, the battery 1000 according to the present embodiment is provided with the insulating member 700 having the second portion 600 that serves as a vent path, thereby improving reliability and safety as described above. Furthermore, Patent Documents 1 and 2 do not disclose or suggest the configuration described in the present embodiment in which the insulating member 700 has the second portion 600.

[0120] [Variation 1] Variation 1 of the embodiment will be described below. Note that in the following description of Variation 1, differences from the above embodiment will be mainly described, and explanations of commonalities will be omitted or simplified. The same applies to Variations 2 and subsequent variations described below; in the description of each variation, differences from the above embodiment and each variation will be mainly described, and explanations of commonalities will be omitted or simplified.

[0121] 2A and 2B are cross-sectional and plan views showing a schematic configuration of a battery 1100 according to a first modified example of the embodiment. Specifically, FIG. 2A is a cross-sectional view of the battery 1100 according to this modified example, and FIG. 2B is a plan view of the battery 1100 as viewed from below in the z-axis direction. FIG. 2A shows a cross section taken along line IIa-IIa in FIG. 2B. In addition, FIG. 2B shows the outlines of the battery element 400 and the second portion 610, which are not actually visible, in dashed lines.

[0122] As shown in Figure 2, the battery 1100 of this modified example differs from the battery 1000 of the embodiment in that it has an insulating member 710 having a first portion 500 and a second portion 610 instead of the insulating member 700 having a first portion 500 and a second portion 600.

[0123] The second portion 610 has a different hardness from the second portion 600. The second portion 610 includes a plurality of bubbles 601, similar to the second portion 600, and has a lower density than the first portion 500. The shape and arrangement of the second portion 610 are the same as those of the second portion 600.

[0124] The second portion 610 is softer than the first portion 500. This makes the second portion 610 more likely to be selectively damaged when the internal pressure of the insulating member 710 increases, making it easier for a vent path to be formed in the insulating member 710. The softness of the first portion 500 and the second portion 610 can be confirmed, for example, by evaluating their relative softness using a micro-Vickers test. For example, when an indenter is pressed against a cross section with the same pressure, the larger the size of the indentation mark left behind, the softer the material is determined to be.

[0125] As long as the second portion 610 is formed of an insulating material softer than the first portion 500, the insulating materials forming the first portion 500 and the second portion 610 are not particularly limited. For example, the first portion 500 includes a first insulating resin, and the second portion 610 includes a second insulating resin softer than the first insulating resin. The second insulating resin may have a resin composition softer than the material constituting the first insulating resin. The first insulating resin and the second insulating resin may each be a thermosetting resin that hardens by crosslinking, such as an epoxy resin, a silicone resin, or an acrylic resin. The second insulating resin may have a lower degree of crosslinking than the first insulating resin. This allows the second insulating resin to be softer by changing the curing temperature, specifically, by lowering the curing temperature of the second insulating resin compared to the first insulating resin, even when the same pre-cured resin material is used. Therefore, a second insulating resin softer than the first insulating resin can be easily formed.

[0126] The insulating member 710 can be produced, for example, by pouring the uncured resin material of the first portion 500 into a mold, then placing the previously prepared second portion 610 inside and curing it; however, the manufacturing method is not limited thereto. For example, the uncured insulating resin of the first portion 500 may be poured into a mold, and then the uncured insulating resin of the second portion 610 may be poured in. Furthermore, when the curing temperatures of the first portion 500 and the second portion 610 are different, for example, the uncured insulating resin of the first portion 500 may be poured into a mold and cured so as to form a cavity at the position of the second portion 610, and then the uncured insulating resin of the second portion 610 may be poured into the formed cavity and cured. Alternatively, the insulating member 710 may be formed using the second portion 610, whose uncured insulating resin has been cured in advance at a relatively low temperature.

[0127] [Modification 2] Next, Modification 2 of the embodiment will be described.

[0128] 3A and 3B are cross-sectional and plan views showing a schematic configuration of a battery 1200 according to a second modification of the embodiment. Specifically, FIG. 3A is a cross-sectional view of the battery 1200 according to this modification, and FIG. 3B is a plan view of the battery 1200 as viewed from below in the z-axis direction. FIG. 3A shows a cross section taken along line IIIa-IIIa in FIG. 3B. In addition, FIG. 3B shows the outlines of the battery element 400 and the second portion 620, which are not actually visible, in dashed lines.

[0129] As shown in FIG. 3 , the battery 1200 of this modification differs from the battery 1100 of the first modification in that it has an insulating member 720 having a first portion 500 and a second portion 620 instead of an insulating member 710 having a first portion 500 and a second portion 610.

[0130] The second portion 620 has a configuration in which the above-described second portion 610 further includes a plurality of thermally expandable particles 602. Note that the second portion 620 may have a configuration in which the above-described second portion 600 further includes a plurality of thermally expandable particles 602. Furthermore, the second portion in another modified example described below may include the thermally expandable particles 602.

[0131] The thermally expandable particles 602 are, for example, expandable particles. Expandable particles are particles that generate gas at a predetermined temperature, and are composed of, for example, microcapsules filled with a volatile material. In the microcapsules, for example, tiny capsules made of a thermoplastic resin are filled with a volatile material. The microcapsules are not particularly limited as long as they are electrochemically stable. Various insulating materials can be used for the capsule portion of the microcapsules, and for example, a thermally expandable resin is used.

[0132] The thermally expandable resin is a resin with a large thermal expansion coefficient among resins, and examples of the thermally expandable resin include polyamide (PA), polyimide, polyamideimide, wholly aromatic polyamide, polyetherimide, polysulfone, polyethersulfone, polyethylene terephthalate (PET), etc., and these can be used alone or in combination. Microcapsules with a median diameter of 1 μm or more and 10 μm or less at room temperature can be used.

[0133] The volatile material in the microcapsules is liquid at room temperature (e.g., 23°C), and this volatile material boils and turns into gas due to heat generation from the battery element 400, causing the microcapsules to expand significantly. Various types of volatile materials can be used, such as hydrocarbons, halogenated hydrocarbons, and alkylsilanes.

[0134] The temperature at which the second portion 620 becomes susceptible to breakage can be adjusted by selecting the boiling point of the volatile material in the microcapsules and the softening temperature of the thermally expandable resin. The expansion initiation temperature of the expandable particles may be, for example, 100°C or higher and 300°C or lower, 150°C or higher and 250°C or lower, 200°C or lower, or 180°C or lower. The thermal expansion coefficient of the expandable particles may be, for example, 30 times or higher and 80 times or lower. Furthermore, a mixture of expandable particles with different thermal expansion coefficients may be used as the expandable particles. The thermal expansion coefficient of the expandable particles can be observed by heating the expandable particles alone.

[0135] The expandable particles are not limited to the microcapsules described above, but may be any particles that generate gas at a predetermined temperature. For example, the expandable particles may be particles of an expandable material alone, such as solid particles of a sublimable material or solid particles of a thermally decomposable material. Furthermore, the thermally expandable particles 602 are not limited to expandable particles, but may be non-expandable particles as long as they are made of a material that expands more easily than the insulating material that constitutes the first portion 500. For example, the non-expandable particles may be particles of the thermally expandable resin described above.

[0136] By including the thermally expandable particles 602 in the second portion 620, the second portion 620 is more likely to be selectively damaged when the battery element 400 generates heat, and a vent path is more likely to be formed in the insulating member 720. The thermally expandable particles 602 may also be in contact with the battery element 400. This allows a vent path to be formed with good responsiveness when the battery element generates abnormal heat.

[0137] The above configuration makes it easier to form a vent path in the battery 1200, and also makes it possible to control the temperature at which the vent path is formed over a wide range, thereby improving the safety of the battery 1200.

[0138] [Modification 3] Next, Modification 3 of the embodiment will be described.

[0139] 4A and 4B are cross-sectional and plan views showing a schematic configuration of a battery 1300 according to a third modification of the embodiment. Specifically, FIG. 4A is a cross-sectional view of the battery 1300 according to this modification, and FIG. 4B is a plan view of the battery 1300 as viewed from below in the z-axis direction. FIG. 4A shows a cross section taken along line IVa-IVa in FIG. 4B. In addition, FIG. 4B shows the outlines of the battery element 400 and the second portion 630, which are not actually visible, in dashed lines.

[0140] As shown in FIG. 4 , the battery 1300 of this modified example differs from the battery 1000 of embodiment 1 in that it includes an insulating member 730 having a first portion 500 and a second portion 630 instead of the insulating member 700 having a first portion 500 and a second portion 600.

[0141] The second portion 630 has a different shape from the above-described second portion 600. The second portion 630 includes a plurality of bubbles 601 similar to the second portion 600, and has a lower density than the first portion 500. The insulating material constituting the second portion 630 is, for example, the same as that of the second portion 600, but may also be the same as that of the second portion 610 or 620.

[0142] The second portion 630 is branched and contacts the battery element 400 at multiple locations that are spaced apart from one another. In the second portion 630, the respective portions that contact the battery element 400 at multiple locations join together, and the second portion 630 is exposed at one location on the outer surface 701 of the insulating member 730. In the example shown in Fig. 4, the second portion 630 contacts the battery element 400 at two locations on the side surface 401, but the locations where the second portion 630 and the battery element 400 contact may include locations other than the side surface 401. Furthermore, the second portion 630 may contact the battery element 400 at three or more locations.

[0143] By having such second portion 630 in insulating member 730, vent paths corresponding to multiple locations that may generate heat in battery element 400 can be formed in insulating member 730. Furthermore, by adjusting the number of branches in second portion 630 and the way in which they are branched, the internal pressure of insulating member 730 at which second portion 630 breaks can be adjusted.

[0144] [Modification 4] Next, Modification 4 of the embodiment will be described.

[0145] 5A and 5B are cross-sectional and plan views showing a schematic configuration of a battery 1400 according to a fourth modification of the embodiment. Specifically, FIG. 5A is a cross-sectional view of the battery 1400 according to this modification, and FIG. 5B is a plan view of the battery 1400 as viewed from below in the z-axis direction. FIG. 5A shows a cross section taken along line Va-Va in FIG. 5B. In addition, FIG. 5B shows the outlines of the battery element 400 and the second portion 640, which are not actually visible, in dashed lines.

[0146] As shown in FIG. 5 , the battery 1400 of this modified example differs from the battery 1000 of embodiment 1 in that it includes an insulating member 740 having a first portion 500 and a second portion 640 instead of the insulating member 700 having a first portion 500 and a second portion 600.

[0147] The second portion 640 differs from the second portion 600 in that it is disposed along the lead terminal 800b. The second portion 640 is in contact with the lead terminal 800b. The second portion 640 includes a plurality of bubbles 601, similar to the second portion 600, and has a lower density than the first portion 500. The insulating material constituting the second portion 640 is, for example, the same as that of the second portion 600, but may also be the same as that of the second portion 610 or 620.

[0148] 5 , the second portion 640 is disposed along the location where the bent portions 801b and 802b of the lead terminal 800b are formed, and the second portion 640 is also bent. A portion of the second portion 640 is disposed between the side surface 401 and a portion of the lead terminal 800b that faces the side surface 401 due to the bend at the bent portion 801b. The second portion 640 may be disposed along the lead terminal 800a. The second portion 640 is disposed along the entire portion of the lead terminal 800b that is located outside the side surface 401 (the negative side in the x-axis direction), but may also be disposed along a portion of that portion.

[0149] The second portion 640 may contain a silicone resin or a silane coupling agent. This improves the adhesion between the second portion 640 and the lead terminal 800b. This prevents moisture and air from penetrating into the insulating member 740 from the interface between the second portion 640 and the lead terminal 800b, thereby preventing deterioration of the battery element 400. The silicone resin or the silane coupling agent may be unevenly distributed at the interface between the second portion 640 and the lead terminal 800b. Alternatively, the second portion 640 may contain both the silicone resin and the silane coupling agent.

[0150] As described above, in the battery 1400, the second portion 640 is disposed along the lead terminal 800b, so that the internal pressure of the insulating member 740 can be released along the rigid wall surface of the lead terminal 800b. Because the wall surface of the lead terminal 800b, which is made of a conductor, is less likely to be damaged, a vent path can be formed at a precise position. Furthermore, pressure tends to concentrate at the interface between the lead terminal 800b and the second portion 640, making it easier for a vent path to form along the interface even at low pressure, making it easier for a vent path to form even at relatively low pressure.

[0151] Furthermore, in the battery 1400, the lead terminal 800b has bent portions 801b and 802b, and therefore the internal pressure of the insulating member 740, in which the second portion 640 serves as a vent path, can be adjusted by adjusting the degree and position of the bend of the lead terminal 800b. Furthermore, the lead terminal 800b may have a step due to a change in thickness of the lead terminal 800b, instead of or in addition to the bent portions 801b and 802b. This also makes it possible to adjust the internal pressure in which the second portion 640 serves as a vent path.

[0152] [Modification 5] Next, Modification 5 of the embodiment will be described.

[0153] 6A and 6B are cross-sectional and plan views showing a schematic configuration of a battery 1500 according to a fifth variation of the embodiment. Specifically, FIG. 6A is a cross-sectional view of the battery 1500 according to this variation, and FIG. 6B is a plan view of the battery 1500 as viewed from below in the z-axis direction. FIG. 6A shows a cross section taken along line VIa-VIa in FIG. 6B. In addition, FIG. 6B shows the outlines of the battery element 400 and the second portion 600, which are not actually visible, in dashed lines.

[0154] As shown in FIG. 6 , the battery 1500 of this modified example differs from the battery 1000 of embodiment 1 in that, instead of the insulating member 700, it is provided with an insulating member 750 in which another second part 600 is added to the insulating member 700.

[0155] The insulating member 750 has a plurality of second portions 600. In the example shown in FIG. 6 , the insulating member 750 has two second portions 600: a second portion 600 that contacts the first electrode layer 100 at the side surface 401, and a second portion 600 that contacts the second electrode layer 200 at the side surface 402. The number of second portions 600 included in the insulating member 750 may be three or more. There are no particular limitations on the position at which the second portions 600 contact the battery element 400. The insulating member 750 may have any of the second portions according to the respective modified examples instead of at least one of the plurality of second portions 600.

[0156] By having the insulating member 750 have a plurality of second portions 600, vent paths corresponding to a plurality of locations in the battery element 400 where heat may be generated can be formed in the insulating member 750.

[0157] [Modification 6] Next, Modification 6 of the embodiment will be described.

[0158] 7A and 7B are cross-sectional and plan views showing a schematic configuration of a battery 1600 according to a sixth variation of the embodiment. Specifically, FIG. 7A is a cross-sectional view of the battery 1600 according to this variation, and FIG. 7B is a plan view of the battery 1600 as viewed from below in the z-axis direction. FIG. 7A shows a cross section taken along line VIIa-VIIa in FIG. 7B. In addition, FIG. 7B shows the outlines of the battery element 400 and the second portion 660, which are not actually visible, in dashed lines.

[0159] As shown in FIG. 7 , the battery 1600 of this modified example differs from the battery 1000 of embodiment 1 in that it includes an insulating member 760 having a first portion 500 and a second portion 660 instead of the insulating member 700 having a first portion 500 and a second portion 600.

[0160] The second portion 660 differs from the second portion 600 in the arrangement within the insulating member 760. The second portion 660 includes a plurality of bubbles 601, similar to the second portion 600, and has a lower density than the first portion 500. The insulating material constituting the second portion 660 is, for example, the same as that of the second portion 600, but may also be the same as that of the second portion 610 or 620.

[0161] The second portion 660 is disposed so as to include a position where the distance between the battery element 400 and the outer surface 701 of the insulating member 760 is longest. The distance between the battery element 400 and the outer surface 701 of the insulating member 760 at a certain position on the outer surface 701 is the distance from the certain position to the nearest surface of the battery element 400 in a cross-sectional view of the portion including the battery element 400 as shown in (a) of Figure 7. In the example shown in Figure 7, the second portion 660 extends from the ridge where the side surface 401 and the main surface 405 intersect toward the ridge of the outer surface 701 that is nearest to the ridge.

[0162] The second portion 660 is disposed so as to include the position where the distance between the battery element 400 and the outer surface 701 of the insulating member 760 is longest, thereby increasing the pressure at which a vent path is formed in the insulating member 760. Furthermore, the long extension of the second portion 660 can suppress the intrusion of moisture, air, and the like into the insulating member 760.

[0163] [Battery Manufacturing Method] Next, an example of a battery manufacturing method according to the present embodiment will be described. The following description will focus on a method for manufacturing the battery 1000 according to the above-described embodiment. The batteries according to each modification of the embodiment can also be manufactured by appropriately applying the manufacturing method for the battery 1000. Note that the manufacturing method described below is just an example, and the manufacturing methods for the batteries according to the above-described embodiment and each modification are not limited to the following example.

[0164] In the following description, the first active material layer 120 is a positive electrode active material layer, the first current collector 110 is a positive electrode current collector, the second active material layer 220 is a negative electrode active material layer, and the second current collector 210 is a negative electrode current collector. Therefore, the first electrode layer 100 is a positive electrode layer, and the second electrode layer 200 is a negative electrode layer.

[0165] First, pastes are prepared for use in printing the first active material layer 120 and the second active material layer 220. The solid electrolyte material used in the mixture for each of the first active material layer 120 and the second active material layer 220 is, for example, Li SiO 2 having an average particle size of approximately 2 μm and containing triclinic crystals as its main component. ２ S-P ２ S ５A glass powder of a sulfide system is prepared. This glass powder contains 3×10 －３ From 4 x 10 －３ As the positive electrode active material, for example, a layered Li-Ni-Co-Al composite oxide (LiNi) having an average particle diameter of about 3 μm can be used. ０．８ Co ０．１５ Al ０．０５ O ２ ) powder is used. A paste for a positive electrode active material layer is prepared by dispersing a mixture containing the above-mentioned positive electrode active material and the above-mentioned glass powder in an organic solvent or the like. In addition, as the negative electrode active material, for example, powder of natural graphite having an average particle size of about 3 μm is used. Similarly, a paste for a negative electrode active material layer is prepared by dispersing a mixture containing the above-mentioned negative electrode active material and the above-mentioned glass powder in an organic solvent or the like.

[0166] Next, copper foil having a thickness of, for example, approximately 15 μm is prepared as the material to be used for the first current collector 110 and the second current collector 210. A paste for the positive electrode active material layer and a paste for the negative electrode active material layer are printed in a predetermined shape on one surface of each copper foil by screen printing. The thickness at this time is, for example, 20 μm to 30 μm. The paste for the positive electrode active material layer and the paste for the negative electrode active material layer are dried, for example, at 80°C to 130°C, to a thickness of 12 μm to 18 μm. Then, as necessary, the periphery of the printed matter is cut to a desired shape. A so-called Thomson blade, a punching die, or a laser may be used for cutting. The outer peripheral surface may also be inclined depending on the cutting method, for example, by cutting the sample at an angle.

[0167] Through the above steps, a first electrode layer 100 is obtained in which a first active material layer 120 is laminated on a first current collector 110. Also, a second electrode layer 200 is obtained in which a second active material layer 220 is laminated on a second current collector 210.

[0168] Next, a paste for a solid electrolyte layer is prepared by dispersing the above-described glass powder in an organic solvent or the like. Then, the above-described paste for a solid electrolyte layer is printed on the first active material layer 120 and the second active material layer 220 using a metal mask. The paste for a solid electrolyte layer is then dried, for example, at a temperature of 80°C or higher and 130°C or lower. As a result, the solid electrolyte layer 300 is laminated on each of the first electrode layer 100 and the second electrode layer 200. The first electrode layer 100 and the second electrode layer 200, each having the solid electrolyte layer 300 laminated thereon, are then laminated such that the two solid electrolyte layers 300 face each other and contact each other. This results in a laminate in which the first electrode layer 100, the solid electrolyte layer 300, and the second electrode layer 200 are laminated.

[0169] Next, a sheet having a thickness of about 70 μm and an elastic modulus of 5×10 ６ An elastic sheet of about 300 MPa is inserted into the laminate. With this configuration, pressure is applied to the laminate via the elastic sheet. Thereafter, the pressure mold is pressed for 90 seconds while being heated to 50° C. at a pressure of 300 MPa, for example, to obtain the battery element 400.

[0170] Next, two lead terminals 800a and 800b are prepared. For example, 300 μm thick stainless steel (SUS) flat plates are prepared as the lead terminals 800a and 800b. The lead terminal 800a is bonded to the main surface 405 of the battery element 400 with a silver-based conductive resin, and the lead terminal 800b is bonded to the main surface 406 of the battery element 400 with a silver-based conductive resin, and the conductive resin is thermally cured. The curing temperature is, for example, one hour or more and two hours or less. In this manner, the lead terminals 800a and 800b are connected to the battery element 400.

[0171] The lead terminals 800a and 800b are bent so as not to come into contact with the side surfaces of the battery element 400, and bent portions 801a, 802a, 801b, and 802b are formed.

[0172] Next, a thermosetting resin, such as epoxy resin, is placed in a mold as the raw material for the insulating member 700, and the battery element 400, with the lead terminals 800a and 800b connected, is immersed and placed in a predetermined position. In other words, the battery element 400 is embedded in the epoxy resin that forms the insulating member 700. At this time, a needle-shaped dispenser with a diameter of approximately 100 μm is used, for example, to repeatedly inject gas from the tip of the dispenser at predetermined positions in the epoxy resin, thereby forming multiple bubbles 601. Any gas, such as air, nitrogen, argon, or carbon dioxide, can be used as the gas. The diameter of the bubbles 601 can be controlled by the diameter of the dispenser and the amount of gas injected. By intermittently injecting the gas, multiple bubbles 601 can be individually created. Due to the surface tension of the epoxy resin, the injected gas stabilizes to a minimum volume, forming spherical, closed bubbles. To create larger bubbles 601, the amount of gas injected can be increased. Note that gas injection can also be performed using equipment other than a dispenser.

[0173] The epoxy resin is then thermally cured. The curing temperature depends on the thermosetting resin, but is, for example, 180°C or higher and 230°C or lower. This forms an insulating member 700 having a first portion 500 containing the battery element 400 and a second portion 600 containing a plurality of bubbles 601. Furthermore, in the above method, the first portion 500 and the second portion 600 are integrally formed. The curing time is, for example, 1 hour or higher and 2 hours or lower. After curing, the lead terminals 800a and 800b exposed from the insulating member 700 are bent to form the connection terminal portions of the battery 1000. In this manner, the battery 1000 is obtained.

[0174] The method and order of forming battery 1000 according to this embodiment are not limited to the above example. For example, second portion 600 having multiple bubbles 601 formed therein may be produced separately from first portion 500, and then second portion 600 may be immersed in the epoxy resin that will become first portion 500 to form insulating member 700. Alternatively, multiple bubbles 601 may be formed by adding a foaming agent that foams at a temperature equal to or lower than the curing temperature to a thermosetting resin such as epoxy resin before curing.

[0175] In the above-described manufacturing method, the paste for first active material layer 120, the paste for second active material layer 220, and the paste for solid electrolyte layer 300 are applied by printing, but the method is not limited to this. Examples of printing methods include doctor blade, calendar, spin coating, dip coating, inkjet, offset, die coating, and spraying.

[0176] (Other Embodiments) While the battery according to the present disclosure has been described above based on the embodiments and modifications, the present disclosure is not limited to these embodiments and modifications. As long as they do not deviate from the gist of the present disclosure, various modifications that would occur to a person skilled in the art to the embodiments and modifications, and other forms constructed by combining some of the components of the embodiments and modifications, are also included in the scope of the present disclosure.

[0177] For example, in the above-described embodiment and each modified example, the battery element 400 includes one each of the first electrode layer 100, the solid electrolyte layer 300, and the second electrode layer 200. However, this is not limiting. The battery element 400 may be an element in which a plurality of stacked bodies each including the first electrode layer 100, the solid electrolyte layer 300, and the second electrode layer 200 are stacked.

[0178] Furthermore, for example, in the above-described embodiment and each modification, the second portions 600 , 610 , 620 , 630 , 640 , 650 and 660 may not have bubbles 601 as long as they are more easily broken than the first portion 500 .

[0179] Furthermore, the above-described embodiments and modifications can be subject to various changes, substitutions, additions, omissions, etc. within the scope of the claims or their equivalents.

[0180] The battery according to the present disclosure can be used as a secondary battery such as an all-solid-state lithium-ion battery used in various electronic devices or automobiles, for example.

[0181] 1000, 1100, 1200, 1300, 1400, 1500, 1600 Battery 100 First electrode layer 110 First current collector 120 First active material layer 200 Second electrode layer 210 Second current collector 220 Second active material layer 300 Solid electrolyte layer 400 Battery element 401, 402, 403, 404 Side surface 405, 406 Main surface 500 First portion 600, 610, 620, 630, 640, 660 Second portion 601 Air bubbles 602 Thermally expandable particles 700, 710, 720, 730, 740, 750, 760 Insulating member 701 Outer surface 800a, 800b Lead terminal 801a, 801b, 802a, 802b bending part

Claims

1. A battery comprising: a battery element having a laminated structure in which a first electrode layer, a solid electrolyte layer, and a second electrode layer are laminated in this order; and an insulating member sealing the battery element, wherein the insulating member has: a first portion that contains the battery element; and a second portion that selectively breaks when internal pressure of the insulating member increases, to become a vent path that passes through the first portion from a surface of the battery element to an outer surface of the insulating member.

2. The battery of claim 1, wherein the second portion contains air bubbles and has a lower density than the first portion.

3. The battery according to claim 2, wherein the second portion includes a plurality of the gas bubbles.

4. The battery according to claim 2 or 3, wherein the first portion and the second portion contain the same insulating resin.

5. The battery according to claim 1, wherein the first portion includes a first insulating resin.

6. The battery according to claim 5, wherein the first insulating resin is a thermosetting resin.

7. The battery according to any one of claims 1 to 3, wherein the second portion is softer than the first portion.

8. The battery according to claim 7, wherein the first portion includes a first insulating resin, and the second portion includes a second insulating resin softer than the first insulating resin.

9. The battery according to claim 8, wherein the second insulating resin is a thermosetting resin.

10. The battery according to claim 9, wherein the first insulating resin and the second insulating resin are thermosetting resins that harden by cross-linking, and the second insulating resin has a lower degree of cross-linking than the first insulating resin.

11. The battery according to any one of claims 1 to 3, wherein the second portion includes thermally expandable particles.

12. The battery according to claim 11, wherein the thermally expandable particles are expandable particles.

13. The battery of claim 12, wherein the expandable particles are composed of microcapsules filled with a volatile material.

14. The battery according to claim 12, wherein the expandable particles have an expansion initiation temperature of 150°C or higher and 250°C or lower.

15. The battery according to any one of claims 1 to 3, wherein the second portion is positioned so as to include a position where the distance between the battery element and the outer surface of the insulating member is shortest.

16. The battery according to any one of claims 1 to 3, wherein the second portion is positioned so as to include a position where the distance between the battery element and the outer surface of the insulating member is longest.

17. The battery of any one of claims 1 to 3, wherein the second portion is curved.

18. The battery of any one of claims 1 to 3, wherein the second portion is branched.

19. The battery according to any one of claims 1 to 3, further comprising a lead terminal connected to the first electrode layer or the second electrode layer and extending through the insulating member to the outside of the insulating member, and the second portion is disposed along the lead terminal.

20. The battery according to claim 19, wherein the lead terminal has a bend or step in the insulating member.

21. The battery of claim 19, wherein the second portion comprises a silicone resin.

22. The battery of claim 19, wherein the second portion includes a silane coupling agent.

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