WO2025047080A1 - Battery - Google Patents

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

This disclosure relates to batteries.

Patent Document 1 discloses a laminated battery in which the side surfaces of the battery element, which is made up of the outer edges of the positive electrode layer, solid electrolyte layer, and negative electrode layer, are coated with resin.

Patent document 2 also discloses a battery in which the battery element is covered with an insulating material.

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

In conventional technology, there is a demand for batteries that are highly reliable and safe.

A battery according to one embodiment 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. The insulating member has a first portion that contains 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 penetrates the first portion from the surface of the battery element to the outer surface of the insulating member.

This disclosure makes it possible to provide a battery with excellent reliability and safety.

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 example of the embodiment. FIG. 3 is a cross-sectional view and a plan view showing a schematic configuration of a battery according to a second modification of the embodiment. FIG. 4 is a cross-sectional view and a plan view showing a schematic configuration of a battery according to a third modification of the embodiment. FIG. 5 is a cross-sectional view and a plan view showing a schematic configuration of a battery according to a fourth modified example of the embodiment. FIG. 6 is a cross-sectional view and a plan view showing a schematic configuration of a battery according to a fifth modified example of the embodiment. FIG. 7 is a cross-sectional view and a plan view showing a schematic configuration of a battery according to a sixth modified example of the embodiment.

(Summary of the Disclosure)
As an outline of the present disclosure, an example of a battery according to the present disclosure is shown below.

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, the insulating member having a first portion that contains 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 penetrates the first portion from the surface of the battery element to the outer surface of the insulating member.

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 generates abnormal heat or burns, causing the internal pressure of the insulating member to rise, the second portion of the insulating member is selectively damaged, releasing the internal pressure. This prevents the insulating member and battery element from breaking into pieces and scattering into the surrounding area. These effects make it possible to realize a battery that is highly reliable and safe.

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

As a result, when the internal pressure of the insulating member increases, the second portion becomes more likely to be selectively damaged, making it easier for the internal pressure of the insulating member to be released.

Also, for example, the battery according to the third aspect of the present disclosure is the battery according to the second aspect, in which the second portion includes a plurality of the bubbles.

As a result, the internal pressure of the insulating member at which the second portion breaks and the airtightness of the insulating member can be adjusted by the number of bubbles. Therefore, for example, it is possible to obtain a highly reliable and safe battery that meets the purpose, taking into account the application, etc.

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

This allows the first and second parts to be formed using the same insulating resin depending on whether or not there are air bubbles, making it easy to form the insulating member.

Also, for example, a battery according to a fifth aspect of the present disclosure is a battery according to any one of the first to fourth aspects, in which the first portion includes a first insulating resin.

This allows the first part containing the battery element to adhere more closely to the battery element, preventing moisture and air from entering the battery element. In addition, the first insulating resin is more likely to absorb the expansion and contraction of the battery element caused by charge/discharge and thermal cycles. This makes it possible to prevent structural defects such as cracks from occurring in the insulating member and battery element. This allows for the realization of a highly reliable battery.

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

As a result, the first part can be formed by immersing the battery element in a material containing the first insulating resin and thermally curing it, making it easy to form the insulating member.

Also, for example, a battery according to a seventh aspect of the present disclosure is a battery according to any one of the first to sixth aspects, in which the second portion is softer than the first portion.

As a result, when the internal pressure of the insulating member increases, the second portion is more likely to be selectively damaged, making it easier for the internal pressure of the insulating member to be released.

Also, for example, a battery according to an eighth aspect of the present disclosure is a battery according to the seventh aspect, in which 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.

This allows the second part to adhere more easily to the battery element and the first part, improving the airtightness of the insulating member.

For example, the battery according to the ninth aspect of the present disclosure is the battery according to the eighth aspect, in which the second insulating resin is a thermosetting resin.

As a result, the second part can be formed by thermally curing the material containing the second insulating resin, making it easy to form the insulating member.

Also, for example, a battery according to a tenth aspect of the present disclosure is a battery according to the ninth aspect, in which the first insulating resin and the second insulating resin are thermosetting resins that harden by crosslinking, and the second insulating resin has a lower degree of crosslinking than the first insulating resin.

As a result, the second insulating resin can be made softer than the first insulating resin simply by adjusting the degree of cross-linking through the curing temperature, etc., making it easy to form the insulating member.

Also, for example, a battery according to an eleventh aspect of the present disclosure is a battery according to any one of the first to tenth aspects, in which the second portion includes thermally expandable particles.

As a result, when the battery element generates heat, the heat-expanding particles expand, making the second part more susceptible to damage. This makes it possible to prevent damage and fire around the battery, resulting in a highly reliable battery.

Also, for example, a battery according to a twelfth aspect of the present disclosure is a battery according to the eleventh aspect, in which the thermally expandable particles are foamable particles.

As a result, when the battery element heats up, the expandable particles expand, making the second part more susceptible to damage.

Also, for example, a battery according to a thirteenth aspect of the present disclosure is a battery according to the twelfth aspect, in which the expandable particles are composed of microcapsules filled with a volatile material.

This allows the expansion rate and expansion temperature of the foamable particles to be controlled by adjusting the type and content of the volatile material.

Also, for example, a battery according to a fourteenth aspect of the present disclosure is a battery according to the twelfth or thirteenth aspect, in which the foaming start temperature of the expandable particles is 150°C or higher and 250°C or lower.

As a result, when the battery element generates abnormal heat, the expandable particles expand, forming a vent path before the battery element and insulating components become excessively hot.

Also, 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, in which 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.

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

Also, 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, in which 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.

This allows the pressure at which the second section becomes a vent path to be increased.

Also, for example, a battery according to a seventeenth aspect of the present disclosure is a battery according to any one of the first to sixteenth aspects, in which the second portion is bent.

As a result, by adjusting the number of bent points in the second section and the manner in which they are bent, it is possible to adjust the internal pressure of the insulating member at which the second section breaks. It is also possible to adjust the position on the outer surface of the insulating member where the internal pressure is released.

Also, for example, a battery according to an 18th aspect of the present disclosure is a battery according to any one of the 1st to 17th aspects, in which the second portion is branched.

As a result, by adjusting the number of branches in the second section and the way in which they are branched, it is possible to adjust the internal pressure of the insulating member at which the second section breaks. It is also possible to adjust the position on the outer surface of the insulating member where the internal pressure is released.

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 disposed along the lead terminal.

This allows the internal pressure of the insulating material to be released along the rigid wall surface of the lead terminal. This makes it possible to form a vent path in the insulating material at a precise position.

Also, for example, a battery according to a twentieth aspect of the present disclosure is a battery according to any one of the first to nineteenth aspects, in which the lead terminal has a bent portion or a step within the insulating member.

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 in the lead terminal.

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

This improves the adhesion between the second part and the lead terminal. This prevents moisture and air from penetrating into the insulating material from the interface between the second part and the lead terminal, thereby preventing deterioration of the battery element.

Also, for example, a battery according to a twenty-second aspect of the present disclosure is a battery according to any one of the nineteenth to twenty-first aspects, in which the second portion includes a silane coupling agent.

This improves the adhesion between the second part and the lead terminal. This prevents moisture and air from penetrating into the insulating material from the interface between the second part and the lead terminal, thereby preventing deterioration of the battery element.

The following describes the embodiment in detail with reference to the drawings.

The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components 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 described in an independent claim are described as optional components.

In addition, in this specification, terms indicating the relationship between elements, such as "parallel," terms indicating the shape of an element, such as "rectangle," and numerical ranges are not expressions that express only a strict meaning, but are expressions that include a substantially equivalent range, for example, a difference of about a few percent.

Furthermore, each figure is not necessarily a precise illustration. In each figure, the same reference numerals are used for substantially the same configuration, and duplicate explanations are omitted or simplified.

In addition, in this specification and the drawings, the x-axis, y-axis, and z-axis refer to the three axes of a three-dimensional Cartesian coordinate system. In the following embodiment, the z-axis direction is the stacking direction of the battery elements. Furthermore, when the shape of the battery elements in a plan view is rectangular, the x-axis and y-axis are directions parallel to the first side of the rectangle and the second side perpendicular to the first side, respectively.

In addition, in this specification, the "stacking direction" corresponds to the direction perpendicular to the principal surface of each layer of the battery element. The "principal surface" is the surface with the largest area in each component.

In addition, in this specification, when referring to the "inside" and "outside" of the terms "inner" and "outer," the "inner" refers to the center side of the battery and the "outer" refers to the outer edge side of the battery.

In addition, in this specification, the terms "above" and "below" in the battery configuration do not refer to the upward (vertically upward) and downward (vertically downward) directions 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 "above" and "below" are applied not only to cases where two components are arranged with a gap between them and another component is present between the two components, but also to cases where two components are arranged in close contact with each other and are in contact with each other. In the following explanation, the negative side of the z axis is referred to as "below" or "lower side", and the positive side of the z axis is referred to as "above" or "upper side".

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

FIG. 1 is a cross-sectional view and a plan view showing the schematic configuration of a battery 1000 according to this embodiment. Specifically, FIG. 1(a) is a cross-sectional view of a 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 at the position indicated by line Ia-Ia in FIG. 1(b). Also, FIG. 1(b) shows the outlines of the battery element 400 and second portion 600, which are not actually visible, in dashed lines.

As shown in FIG. 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.

In the battery 1000 shown in FIG. 1, the insulating member 700 exposes portions of the lead terminals 800a and 800b, and contains and seals the battery element 400 and the remaining portions of the lead terminals 800a and 800b. Portions of the lead terminals 800a and 800b are pulled out from the insulating member 700 and exposed, and are connected to an external circuit, for example, as mounting terminal portions.

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 part of the battery element 400. When the internal pressure of the insulating member 700 increases, the second portion 600 selectively breaks to become a vent path that penetrates the first portion 500. The insulating member 700 seals the battery element 400, thereby suppressing deterioration of the characteristics of the battery element 400 due to moisture, air, etc. In addition, 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 to release the internal pressure. Therefore, it is possible to suppress the insulating member 700 and the battery element 400 from being entirely broken into pieces and scattering around. This can improve the reliability and safety of the battery 1000.

Below, each component of the battery 1000 will be described in detail with reference to Figure 1.

[Battery element]
The battery element 400 has a laminated structure in which the first electrode layer 100, the solid electrolyte layer 300, and the second electrode layer 200 are laminated in this order. The planar shape of the battery element 400 is, for example, a rectangular shape. That is, the general shape of the battery 1000 is a flat 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 direction and the y-axis direction) or the maximum width. The planar shape of the battery element 400 may be other polygonal shapes such as a square shape, a hexagonal shape, or an octagonal shape, or may be a circular shape or an elliptical shape. In the drawings related to this specification, in the cross-sectional views showing the configuration of the battery, the thickness of each layer is exaggerated in order to make the layer structure of the battery element 400 easier to understand.

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

Sides 401 and 402 are back-to-back and parallel to each other. Sides 403 and 404 are back-to-back and parallel to each other. Furthermore, side surfaces 401, 402, 403 and 404 stand upright from each edge of main surfaces 405 and 406 in a direction intersecting main surfaces 405 and 406, specifically perpendicular to main surfaces 405 and 406. Side surfaces 401, 402, 403 and 404 are surfaces connecting main surfaces 405 and 406. Side surfaces 401, 402, 403 and 404 are, for example, parallel to the stacking direction of battery element 400. 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. In addition, 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.

In the example shown in FIG. 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.

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 in between, and are in contact with the solid electrolyte layer 300. The 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.

In the example shown in FIG. 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 each the same size in a plan view, and their respective contour shapes match, but this is not limited to the above. For example, the first active material layer 120 and the second active material layer 220 may have different external shapes. This makes it possible to determine the polarity (positive and negative poles) of the battery 1000 and correct the position by viewing 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), for example, and thus reduce polarity errors during production.

The first electrode layer 100 and the second electrode layer 200 are electrodes of opposite polarity. In this 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. In the following, an example will be described in which the first electrode layer 100 is a positive electrode layer including the first active material layer 120 and the first current collector 110 as the positive electrode active material layer and the positive electrode current collector, and the second electrode layer 200 is a negative electrode layer including the second active material layer 220 and the second current collector 210 as the negative electrode active material layer and the negative electrode current collector.

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.

The first active material layer 120 is in contact with one of the main surfaces 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.

The second active material layer 220 is in contact with one of the main surfaces 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.

The first current collector 110 and the second current collector 210 may each be formed of a material having electrical conductivity, 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 made of stainless steel, nickel (Ni), aluminum (Al), iron (Fe), titanium (Ti), copper (Cu), palladium (Pd), gold (Au) or platinum (Pt), or an alloy of two or more of these. The material of the first current collector 110 and the second current collector 210 may be appropriately selected in consideration of the fact that it does not melt or decompose during the manufacturing process, the temperature or pressure used, and the operating potential and electrical conductivity of the battery applied to the first current collector 110 and the second current collector 210. The material of the first current collector 110 and the second current collector 210 may also be selected according to the required tensile strength or heat resistance. The first current collector 110 and the second current collector 210 may be high-strength electrolytic copper foil or a clad material made by laminating foils of different metals.

The thickness 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. In addition, 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 adhesion at the interface between the first current collector 110 and the second current collector 210 and other layers, and improves the mechanical and thermal reliability and cycle characteristics of the battery 1000.

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

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. That is, 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 removed from the crystal structure at a potential higher than that of the negative electrode, and oxidation or reduction occurs accordingly. The type of the positive electrode active material can be appropriately selected according to the type of battery, and a known positive electrode active material 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 transition metal elements include lithium nickel composite oxides such as LiNi _x M _1-x O ₂ (wherein M is at least one element selected from the group consisting of Co, Al, Mn, V, Cr, Mg, Ca, Ti, Zr, Nb, Mo, and W, and x is 0<x≦1), layered oxides such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), and lithium manganate (LiMn ₂ O ₄ ), and lithium manganate (LiMn ₂ O ₄ , Li ₂ MnO ₃ , LiMO ₂ ) having a spinel structure, etc. Examples of phosphate compounds containing lithium and transition metal elements include lithium iron phosphate (LiFePO ₄ ) having an olivine structure, etc. In addition, sulfur (S) and sulfides such as lithium sulfide (Li ₂ S) can be used as the positive electrode active material, and in this case, the positive electrode active material particles can be coated with or added with lithium niobate (LiNbO ₃ ) or the like and used as the positive electrode active material. Note that only one of these materials may be used as the positive electrode active material, or two or more of these materials may be used in combination.

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 solid electrolytes, conductive assistants such as acetylene black, and binding binders such as polyethylene oxide or polyvinylidene fluoride. By mixing the positive electrode active material and other additive materials such as solid electrolytes in a predetermined ratio, the first active material layer 120 can improve the ionic conductivity in the first active material layer 120 and can also improve the electronic conductivity.

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

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 this embodiment, the second active material layer 220 covers the entire one main surface of the second current collector 210.

In this embodiment, the second active material layer 220 is a negative electrode active material layer, and therefore contains at least a negative electrode active material. In other words, the second active material layer 220 is a layer mainly composed of a negative electrode material such as a negative electrode active material. A negative electrode active material refers to a material in which metal ions such as lithium (Li) ions or magnesium (Mg) ions are inserted or removed from the crystal structure at a potential lower than that of the positive electrode, and oxidation or reduction occurs accordingly. The type of negative electrode active material can be appropriately selected depending on the type of battery 1000, and known negative electrode active materials can be used.

As the negative electrode active material, for example, carbon materials such as natural graphite, artificial graphite, graphite carbon fiber, or resin-sintered carbon, or alloy-based materials mixed with a solid electrolyte, etc. can be used. As the alloy-based material, for example, lithium alloys such as LiAl, LiZn, 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 , oxides of lithium and transition metal elements such as lithium titanate (Li ₄ Ti ₅ O ₁₂ ), metal oxides such as zinc oxide (ZnO) and silicon oxide (SiO _x ), etc. can be used. In addition, only one of these materials may be used as the negative electrode active material, or two or more of these materials may be used in combination.

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

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

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 contains at least a solid electrolyte.

The solid electrolyte may be any known solid electrolyte for batteries having ion conductivity. For example, a solid electrolyte that conducts metal ions such as lithium ions or magnesium ions may be used as the solid electrolyte. The type of solid electrolyte may be appropriately selected according to the type of conductive ions. 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 can be confirmed relative to the first active material layer 120 and the second active material layer 220 by, for example, evaluating a cross section cut flat by means of ion milling or the like with a micro Vickers. For example, when an indenter is pressed against the cross section with the same pressure, the larger the size of the indenter mark left is, the softer the layer is determined to be.

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, a lithium-containing sulfide such as 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} PO 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 -ZnS system can be used. As the oxide-based solid electrolyte, for example, lithium-containing metal oxides such as Li ₂ O—SiO ₂ or Li ₂ O—SiO ₂ -P ₂ O ₅ , lithium-containing metal nitrides such as Li _x P _y O _1-z N _z , lithium phosphate (Li ₃ PO ₄ ), or lithium-containing transition metal oxides such as lithium titanium oxide 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.

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.

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

The solid electrolyte layer 300 may be configured as an aggregate of solid electrolyte particles. The solid electrolyte layer 300 may also be configured as a sintered structure of the solid electrolyte.

[Insulating material]
The battery element 400 is embedded in the insulating member 700, and the insulating member 700 seals the battery element 400. Since 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 an outer shape corresponding to the shape of the battery element 400, for example, and in the example shown in FIG. 1, the outer shape of the insulating member 700 is a rectangular parallelepiped shape similar to that of the battery element 400. The insulating member 700 is, for example, a molded resin member formed by embedding the battery element 400 in the center and molding it with a mold. The insulating member 700 may also be formed by applying a resin material so as to cover the entire battery element 400. Since the insulating member 700 does not have a structure such as a laminate of films, for example, the effect of improving the reliability of the battery 1000 as described above is high.

The insulating member 700 has a first portion 500 that contains 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 the outer surface 701 of the insulating member 700. In the example shown in FIG. 1, the outer surface 701 includes a plurality of planes that face and are parallel to each of the side surfaces 401, 402, 403, and 404 and the main surfaces 405 and 406 of the battery element 400.

The first portion 500 covers all of the surfaces of the battery element 400 (in this embodiment, the sides 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 contacts the portions of the side surface 401 that are 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 manner, the effect of the insulating member 700 in improving the reliability of the battery 1000 can be enhanced.

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, releasing the internal pressure of the insulating member 700 to the outside of the insulating member 700.

The second part 600 is arranged to connect the battery element 400 contained in the first part 500 and the outer surface 701 of the insulating member 700. When the internal pressure of the insulating member 700 increases, the second part 600 selectively breaks and becomes a vent path that penetrates the first part 500 from the surface of the battery element 400 to the outer surface 701 of the insulating member 700. The second part 600 is surrounded by the first part 500 and is covered by the first part 500 except for the part that contacts the battery element 400 and the part that constitutes part of the outer surface 701 of the insulating member 700. In the outer surface 701 of the insulating member 700, no step is formed between the first part 500 and the second part 600, and the outer surface 701 is a flat surface. The second part 600 extends straight from the surface of the battery element 400 toward the outer surface 701 of the insulating member 700. The second part 600 may be bent.

The second portion 600 is also positioned to include the 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.

The second portion 600 includes a plurality of bubbles 601 and has a lower density than the first portion 500. Here, "density" does not mean the true density of the material of the first portion 500 and the second portion 600, but 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 independent bubbles, and even if the second portion 600 including the plurality of bubbles 601 exists, the sealing of the battery element 400 by the insulating member 700 is ensured. Some of the plurality of bubbles 601 may be interconnected bubbles. The shape of the bubbles 601 is spherical. The diameter of the bubbles 601 is, for example, 0.1 μm or more and 10 μm or less when converted into a true sphere. In this way, since the second portion 600 contains air bubbles 601 and has a lower density than the first portion 500, when the internal pressure of the insulating member 700 rises, 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 rises 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 is the pressure in the region inside the insulating member 700 where the battery element 400 is located.

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. Since 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 response to an increase in internal pressure due to heat generation or the like in the side portion of the battery element 400, which is prone to short circuits due to structural defects or deformation. In addition, the second portion 600 is in contact with the first electrode layer 100 at the side surface 401, which includes the positive electrode active material layer that is particularly prone to heat generation among the battery element 400.

The position where the second part 600 contacts the battery element 400 is not particularly limited, and the second part 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, and may be formed at any location that is likely to generate heat. The second part 600 may also contact the main surface 405 or 406 of the battery element 400. In this case, the second part 600 may contact the central region of the main surface 405 or 406 that is likely to generate heat during charging and discharging operations. By having the second part 600 contact the main surface 405 or 406, a vent path can be formed with good response to an increase in internal pressure caused by abnormal heat generation in the active material layer that is likely to generate heat during charging and discharging operations.

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, and the ridge line, and any insulating material may be used in 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 contact the main surface or 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.

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

The insulating member 700 is not particularly limited as long as it is made of an insulating material having insulating properties. In the present embodiment, the first portion 500 and the second portion 600 in the insulating member 700 are made of, for example, the same insulating material. The first portion 500 and the second portion 600 contain, for example, the same insulating resin. This makes it easy to form the insulating member 700. In addition, when the first active material layer 120, the second active material layer 220, and the solid electrolyte layer 300 are made of powder materials, the first portion 500 and the second portion 600 can enter the fine unevenness caused 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, and the adhesion between the first portion 500 and the second portion 600 and the battery element 400 is improved.

Examples of insulating resins include epoxy resins, silicone resins, acrylic resins, and fluororesins. The insulating resin may be a thermosetting resin. Thermosetting resins are resins that harden by crosslinking, such as epoxy resins, silicone resins, and acrylic resins.

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

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

[Lead terminal]
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 constant width and thickness.

The lead terminal 800a is connected to the first electrode layer 100 and is pulled 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 point other than the main surface 405, and is not in contact with the side surface of the battery element 400. The lead terminal 800b is connected to the second electrode layer 200 and is pulled 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 point other than the main surface 406, and is not in contact with the side surface 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.

The lead terminal 800a has bent portions 801a and 802a which are bent portions within the insulating member 700. The lead terminal 800a connected to the main surface 405 extends in a direction along the main surface 405 so as to protrude outside the side surface 402, then bends at the bent portion 801a to face the side surface 402 and extend in a direction along the side surface 402, and further bends at the bent portion 802a to extend in a direction away from the side surface 402, and is pulled out from the side surface of the insulating member 700. The portion of the lead terminal 800a between the bent portion 801a and the bent portion 802a faces the side surface 402 via the first portion 500. The bent lead terminal 800a lengthens the intrusion path when moisture, air, etc. intrude into the insulating member 700, and the intrusion of moisture and air into the insulating member 700 can be suppressed. 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 for connection to a mounting board, etc.

The lead terminal 800b has bent portions 801b and 802b which are bent portions within the insulating member 700. The lead terminal 800b connected to the main surface 406 extends in a direction along the main surface 406 so as to protrude outside the side surface 401, then bends at bent portion 801b to face the side surface 401 and extend in a direction along the side surface 401, and further bends at bent portion 802b to extend in a direction away from the side surface 401, and is pulled out from the side surface of the insulating member 700. The portion of the lead terminal 800b between bent portions 801b and 802b faces the side surface 401 via the first portion 500. The bent lead terminal 800b lengthens the intrusion path when moisture, air, etc. intrude into the insulating member 700, and the intrusion of moisture and air into the insulating member 700 can be suppressed. 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 for connection to a mounting board, etc.

Note that lead terminals 800a and 800b have two bent portions within insulating member 700, but the number of bent portions that lead terminals 800a and 800b have is not particularly limited and may be one or three or more. Also, lead terminals 800a and 800b do not have to have a bent portion within insulating member 700. Also, although both connection terminal portions of lead terminals 800a and 800b are provided on the underside of insulating member 700, at least one of them may be provided on the top or side of insulating member 700.

[Effects, etc.]
According to the above configuration, the battery element 400 is sealed with the insulating member 700 having the second portion 600, so that the insulating member 700 protects the battery element 400. Furthermore, when abnormal heat generation or burning occurs in the battery element 400 and the internal pressure of the insulating member 700 rises, the second portion 600 is selectively broken to become a vent path, so that the internal pressure can be released. Therefore, it is possible to prevent the insulating member 700 and the battery element 400 from being broken into pieces and scattering around. Therefore, for example, it is possible to prevent damage and fire around the battery 1000. With such an action and effect, a highly reliable and safe battery can be realized.

Comparing the configuration of the battery 1000 according to this embodiment with the configurations of the batteries described in Patent Documents 1 and 2, there are the following differences.

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 covered with resin. However, it does not have a structure to release pressure when the internal pressure inside the covering resin increases. In other words, the battery in Patent Document 1 differs from the configuration of battery 1000 in that it does not have a structure that serves as a vent path within the resin that covers the battery element. In such a configuration, there is a high possibility that the insulating members and battery element will break into pieces and scatter into the surrounding area. Therefore, if the battery generates abnormal heat, it may cause damage and fire around the battery.

Patent Document 2 also discloses a battery having a structure in which the battery element is covered with an insulating material. However, in the battery in Patent Document 2, the insulating material covering the battery element does not have a structure that serves as a vent path.

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

[Modification 1]
In the following, a first modified example of the embodiment will be described. In the following description of the first modified example, differences from the above embodiment will be mainly described, and descriptions of commonalities will be omitted or simplified. The same is true for the second and subsequent modified examples described below, and in the description of each modified example, differences from the above embodiment and each modified example will be mainly described, and descriptions of commonalities will be omitted or simplified.

FIG. 2 is a cross-sectional view and a plan view showing the schematic configuration of a battery 1100 according to a first variation of the embodiment. Specifically, FIG. 2(a) is a cross-sectional view of the battery 1100 according to this variation, and FIG. 2(b) is a plan view of the battery 1100 as viewed from below in the z-axis direction. FIG. 2(a) shows a cross section taken at the position indicated by line IIa-IIa in FIG. 2(b). Also, FIG. 2(b) shows the outlines of the battery element 400 and the second portion 610, which are not actually visible, in dashed lines.

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

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

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 form in the insulating member 710. The softness of the first portion 500 and the second portion 610 can be confirmed, for example, by evaluating the 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 indenter mark left behind, the softer the part is determined to be.

As long as the second portion 610 is formed of an insulating material softer than the first portion 500, the insulating material forming the first portion 500 and the second portion 610 is 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. For example, a material with a resin composition softer than the material constituting the first insulating resin is used for the second insulating resin. The first insulating resin and the second insulating resin are each 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. As a result, even if the same resin material before hardening is used, the degree of crosslinking can be lowered and the resin can be softened by changing the hardening temperature, specifically, by making the hardening temperature of the second insulating resin lower than the hardening temperature of the first insulating resin. Therefore, a second insulating resin softer than the first insulating resin can be easily formed.

The insulating member 710 can be produced, for example, by pouring the uncured resin material of the first portion 500 into a mold, and then placing the previously prepared second portion 610 in the mold and curing it, but the manufacturing method is not limited. 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. In addition, when the curing temperature is different between the first portion 500 and the second portion 610, for example, the uncured insulating resin of the first portion 500 is poured into a mold and cured so that a cavity is formed at the position of the second portion 610, and then the uncured insulating resin of the second portion 610 is poured into the formed cavity and cured. In addition, the insulating member 710 may be formed using the second portion 610 in which the uncured insulating resin has been cured in advance at a relatively low temperature.

[Modification 2]
Next, a second modification of the embodiment will be described.

FIG. 3 is a cross-sectional view and a plan view showing the schematic configuration of a battery 1200 according to a second variation of the embodiment. Specifically, FIG. 3(a) is a cross-sectional view of the battery 1200 according to this variation, and FIG. 3(b) is a plan view of the battery 1200 as viewed from below in the z-axis direction. FIG. 3(a) shows a cross section taken at the position indicated by line IIIa-IIIa in FIG. 3(b). Also, FIG. 3(b) shows the outlines of the battery element 400 and the second portion 620, which are not actually visible, in dashed lines.

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

The second portion 620 is configured such that the second portion 610 further includes a plurality of thermally expandable particles 602. The second portion 620 may be configured such that the second portion 600 further includes a plurality of thermally expandable particles 602. The second portion in other modified examples described below may also include thermally expandable particles 602.

The thermally expandable particles 602 are, for example, expandable particles. Expandable particles are particles that generate gas at a certain 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. There are no particular limitations on the type of microcapsules, so 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.

Thermal expansion resins are resins with a large thermal expansion coefficient, and examples of thermal expansion resins that can be used include polyamide (PA), polyimide, polyamideimide, wholly aromatic polyamide, polyetherimide, polysulfone, polyethersulfone, polyethylene terephthalate (PET), and the like, either 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.

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.

The temperature at which the second portion 620 becomes easily damaged 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 foaming start 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. In addition, expandable particles with different thermal expansion coefficients may be mixed and used as the expandable particles. The thermal expansion coefficient of the expandable particles can be observed by heating the expandable particles alone.

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. 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 is more easily thermally expandable 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.

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.

The above configuration makes it easier for a vent path to form in the battery 1200, and makes it possible to control the formation temperature over a wide range. This improves the safety of the battery 1200.

[Modification 3]
Next, a third modification of the embodiment will be described.

FIG. 4 is a cross-sectional view and a plan view showing the schematic configuration of a battery 1300 according to a third variation of the embodiment. Specifically, FIG. 4(a) is a cross-sectional view of the battery 1300 according to this variation, and FIG. 4(b) is a plan view of the battery 1300 as viewed from below in the z-axis direction. FIG. 4(a) shows a cross section taken at the position indicated by line IVa-IVa in FIG. 4(b). Also, FIG. 4(b) shows the outlines of the battery element 400 and the second portion 630, which are not actually visible, in dashed lines.

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

The second portion 630 has a different shape from the second portion 600 described above. The second portion 630 contains a plurality of bubbles 601 like 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.

The second portion 630 is branched and contacts the battery element 400 at multiple locations that are spaced apart from each other. In the second portion 630, the 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 side surface 401 of the battery element 400 at two locations, but the locations where the second portion 630 and the battery element 400 contact each other may include locations other than the side surface 401. The second portion 630 may also contact the battery element 400 at three or more locations.

By having the insulating member 730 have such a second portion 630, it is possible to form vent paths in the insulating member 730 that correspond to multiple locations in the battery element 400 where heat may be generated. In addition, by adjusting the number of branches in the second portion 630 and the way in which they are branched, it is possible to adjust the internal pressure of the insulating member 730 at which the second portion 630 breaks.

[Modification 4]
Next, a fourth modified example of the embodiment will be described.

FIG. 5 is a cross-sectional view and a plan view showing the schematic configuration of a battery 1400 according to a fourth variation of the embodiment. Specifically, FIG. 5(a) is a cross-sectional view of the battery 1400 according to this variation, and FIG. 5(b) is a plan view of the battery 1400 as viewed from below in the z-axis direction. FIG. 5(a) shows a cross section taken at the position indicated by line Va-Va in FIG. 5(b). Also, FIG. 5(b) shows the outlines of the battery element 400 and second portion 640, which are not actually visible, in dashed lines.

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

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 contains a plurality of bubbles 601 like 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.

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 part 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 outside the side surface 401 (negative side in the x-axis direction), but may be disposed along a part of that portion.

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 entering 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 silane coupling agent may be unevenly distributed at the interface between the second portion 640 and the lead terminal 800b. The second portion 640 may also contain both the silicone resin and the silane coupling agent.

As described above, in the battery 1400, the second portion 640 is arranged 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. Since the wall surface of the lead terminal 800b, which is made of a conductor, is not easily damaged, the vent path can be formed in a precise position. In addition, pressure tends to concentrate at the interface between the lead terminal 800b and the second portion 640, and a vent path is likely to be formed along the interface even at low pressure, so that a vent path is likely to be formed even at a relatively low pressure.

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

[Modification 5]
Next, a fifth modified example of the embodiment will be described.

FIG. 6 is a cross-sectional view and a plan view showing the schematic configuration of a battery 1500 according to a fifth variation of the embodiment. Specifically, FIG. 6(a) is a cross-sectional view of the battery 1500 according to this variation, and FIG. 6(b) is a plan view of the battery 1500 as viewed from below in the z-axis direction. FIG. 6(a) shows a cross section taken at the position indicated by line VIa-VIa in FIG. 6(b). Also, FIG. 6(b) shows the outlines of the battery element 400 and second portion 600, which are not actually visible, in dashed lines.

As shown in FIG. 6, the battery 1500 of this modified example differs from the battery 1000 of the first embodiment in that, instead of the insulating member 700, it has an insulating member 750 in which a second portion 600 is added to the insulating member 700.

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 401 and a second portion 600 that contacts the second electrode layer 200 at the side 402. The number of second portions 600 that the insulating member 750 has may be three or more. The position where the second portion 600 contacts the battery element 400 is not particularly limited. The insulating member 750 may have any of the second portions according to each modified example instead of at least one of the plurality of second portions 600.

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

[Modification 6]
Next, a sixth modified example of the embodiment will be described.

FIG. 7 is a cross-sectional view and a plan view showing the schematic configuration of a battery 1600 according to a sixth variation of the embodiment. Specifically, FIG. 7(a) is a cross-sectional view of the battery 1600 according to this variation, and FIG. 7(b) is a plan view of the battery 1600 as viewed from below in the z-axis direction. FIG. 7(a) shows a cross section taken at the position indicated by line VIIa-VIIa in FIG. 7(b). Also, FIG. 7(b) shows the outlines of the battery element 400 and second portion 660, which are not actually visible, in dashed lines.

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

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 like 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.

The second portion 660 is arranged to include the 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 FIG. 7(a). In the example shown in FIG. 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.

By positioning the second portion 660 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, the pressure at which a vent path is formed in the insulating member 760 can be increased. In addition, by extending the second portion 660 long, the intrusion of moisture, air, etc. into the insulating member 760 can be suppressed.

[Battery manufacturing method]
Next, an example of a method for manufacturing a battery 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 battery according to each modification of the embodiment can also be manufactured by appropriately applying the method for manufacturing the battery 1000. Note that the manufacturing method described below is only an example, and the manufacturing method for the battery according to the above-described embodiment and each modification is not limited to the following example.

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.

First, each paste used for printing the first active material layer 120 and the second active material layer 220 is prepared. As the solid electrolyte material used for the mixture of the first active material layer 120 and the second active material layer 220, for example, a glass powder of Li ₂ S-P ₂ S _5- based sulfide having an average particle size of about 2 μm and mainly composed of triclinic crystals is prepared. As this glass powder, one having a high ion conductivity of about 3×10 ⁻³ to 4×10 ⁻³ S/cm can be used. As the positive electrode active material, for example, a powder of Li.Ni.Co.Al composite oxide (LiNi _0.8 Co _0.15 Al _0.05 O ₂ ) having an average particle size of about 3 μm and a layered structure 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. As the negative electrode active material, for example, a powder of natural graphite having an average particle size of about 3 μm is used. A paste for a negative electrode active material layer is prepared in the same manner 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.

Next, copper foil with a thickness of, for example, about 15 μm is prepared as the material used for the first current collector 110 and the second current collector 210. The paste for the positive electrode active material layer and the 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 outer periphery of the printed matter is cut to a desired shape. In cutting, a so-called Thomson blade may be used, or a punching die or a laser may be used. In addition, the outer periphery may be inclined depending on the cutting method, for example, by cutting the sample at an angle.

By the above process, 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.

Then, a paste for a solid electrolyte layer is prepared by dispersing the above-mentioned glass powder in an organic solvent or the like. Then, the above-mentioned 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 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. Then, the first electrode layer 100 and the second electrode layer 200 on which the solid electrolyte layer 300 is laminated are laminated so that the two solid electrolyte layers 300 face each other and are in contact with each other. As a result, a laminate in which the first electrode layer 100, the solid electrolyte layer 300, and the second electrode layer 200 are laminated is obtained.

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

Next, two lead terminals 800a and 800b are prepared. For example, flat plates of stainless steel (SUS) with a thickness of 300 μm are prepared as the lead terminals 800a and 800b. The lead terminal 800a is joined to the main surface 405 of the battery element 400 with a silver-based conductive resin, and the lead terminal 800b is joined 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, from 1 hour to 2 hours. In this manner, the lead terminals 800a and 800b are connected to the battery element 400.

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

Next, epoxy resin, for example, is placed in a mold as a thermosetting resin for the insulating member 700, and the battery element 400 to which the lead terminals 800a and 800b are 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 about 100 μm is used to inject gas from the tip of the dispenser at a predetermined position in the epoxy resin repeatedly an arbitrary number of times to form multiple bubbles 601. Any gas can be used as the gas, such as air, nitrogen, argon, or carbon dioxide. The diameter of the bubbles 601 can be controlled by the diameter of the dispenser and the amount of gas injected. By intermittently repeating the injection of gas, multiple bubbles 601 can be created individually. The injected gas is stabilized to a minimum volume by the surface tension of the epoxy resin, and becomes a spherical, independent bubble. To provide a large bubble 601, the amount of gas injected can be increased. Note that equipment other than a dispenser may be used to inject the gas.

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

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

In the above-mentioned manufacturing method, an example is shown in which the paste for the first active material layer 120, the paste for the second active material layer 220, and the paste for the solid electrolyte layer 300 are applied by printing, but this is not limited to this. In addition, examples of printing methods include the doctor blade method, calendar method, spin coating method, dip coating method, inkjet method, offset method, die coating method, and spray method.

Other Embodiments
Although the battery according to the present disclosure has been described above based on the embodiment and each modified example, the present disclosure is not limited to these embodiment and each modified example. As long as it does not deviate from the gist of the present disclosure, various modifications conceived by a person skilled in the art to the embodiment and each modified example, and other forms constructed by combining some of the components in the embodiment and each modified example are also included in the scope of the present disclosure.

For example, in the above 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, but is not limited to this. The battery element 400 may be an element in which multiple laminates of the first electrode layer 100, the solid electrolyte layer 300, and the second electrode layer 200 are stacked.

Also, for example, in the above embodiment and each modified example, the second portions 600, 610, 620, 630, 640, 650, and 660 may not have air bubbles 601 if they are more susceptible to breakage than the first portion 500.

Furthermore, the above-described embodiment and each modified example may be modified, substituted, added, omitted, etc. in various ways within the scope of the claims or their equivalents.

The battery disclosed herein can be used, for example, as a secondary battery such as an all-solid-state lithium-ion battery for use in various electronic devices or automobiles.

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 (22)

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;
an insulating member that seals the battery element;
The insulating member is
A first portion containing 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.
battery. The second portion includes air bubbles and has a lower density than the first portion.
10. The battery of claim 1. The second portion includes a plurality of the bubbles.
3. The battery of claim 2. The first portion and the second portion contain the same insulating resin.
The battery according to claim 2 or 3. The first portion includes a first insulating resin.
The battery according to any one of claims 1 to 3. The first insulating resin is a thermosetting resin.
6. The battery of claim 5. The second portion is softer than the first portion.
The battery according to any one of claims 1 to 3. the first portion includes a first insulating resin;
the second portion includes a second insulating resin that is softer than the first insulating resin;
8. The battery of claim 7. The second insulating resin is a thermosetting resin.
9. The battery of claim 8. the first insulating resin and the second insulating resin are thermosetting resins that are hardened by crosslinking,
The second insulating resin has a lower degree of cross-linking than the first insulating resin.
10. The battery of claim 9. The second portion includes thermally expandable particles.
The battery according to any one of claims 1 to 3. The thermally expandable particles are expandable particles.
12. The battery of claim 11. The expandable particles are composed of microcapsules filled with a volatile material.
13. The battery of claim 12. The expansion starting temperature of the expandable particles is 150° C. or more and 250° C. or less.
13. The battery of claim 12. the second portion is disposed so as to include a position where a distance between the battery element and an outer surface of the insulating member is shortest.
The battery according to any one of claims 1 to 3. the second portion is disposed so as to include a position where the distance between the battery element and the outer surface of the insulating member is longest.
The battery according to any one of claims 1 to 3. The second portion is bent.
The battery according to any one of claims 1 to 3. The second portion is branched.
The battery according to any one of claims 1 to 3. 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;
The second portion is disposed along the lead terminal.
The battery according to any one of claims 1 to 3. The lead terminal has a bent portion or a step in the insulating member.
20. The battery of claim 19. The second portion includes a silicone resin.
20. The battery of claim 19. The second portion includes a silane coupling agent.
20. The battery of claim 19.

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