Secondary batteries

Abstract

To provide a secondary battery capable of improving structural efficiency.SOLUTION: A secondary battery includes a power generation element and an exterior part storing the power generation element therein, wherein the exterior part has a cylindrical part having openings in two opposite surfaces, an inner lid arranged in each of the openings, and a first resin arranged so as to each of the openings and the surface on the opening side of the inner lid, the first resin is arranged so as to fill between the cylindrical part and the inner lid, and the cylindrical part and the inner lid are integrated with each other by the first resin.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present application relates to a secondary battery. [Background technology]

[0002] Batteries such as lithium-ion secondary batteries are widely used as portable power sources for personal computers and mobile devices, and as power sources for vehicle drive. Laminated batteries are known as one example of such batteries. Laminated batteries have a structure in which a power generating element is sealed inside a laminated exterior body formed by overlapping film-like laminate sheets. Furthermore, laminated batteries have a sealed region formed by welding edges of opposing laminated exterior bodies together, with terminals electrically connected to the power generating element protruding outward from the inside of the laminated exterior body. This seals the power generating element inside the laminated exterior body. Furthermore, laminated batteries have a sealed region formed by overlapping and welding laminated sheets on the outside of the power generating element.

[0003] Conventionally, efforts have been made to reduce the size of battery structures. For example, Patent Document 1 discloses a technique for reducing the size of a laminated battery by folding the sealed area at the end of the battery. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-173900 Summary of the Invention [Problem to be solved by the invention]

[0005] Although the technology of Patent Document 1 makes it possible to reduce the size of laminated batteries, further improvements in the structural efficiency of secondary batteries have been desired.

[0006] Miniaturization of laminated batteries can be achieved, for example, by shortening the width of the sealing area (seal width) that sandwiches the electrode terminals. However, the seal width typically must exceed 3 mm. This is due to the following reasons: (1) A short seal width may prevent proper heat welding, resulting in poor sealing. (2) Because the laminate exterior body is not very rigid, a short seal width may cause the adhesive in the sealing area to peel off due to external impact, making it difficult to maintain the adhesive surface. (3) If the terminal is not parallel to the adhesive surface of the laminate exterior body during heat welding, a short seal width weakens the corrective force to restore the tilt, preventing proper heat welding and increasing the likelihood of poor sealing. (4) During heat welding, a short seal width increases the pressure per area applied to the sealing area by the heat welding head, which may cause the metal layer inside the laminate exterior body to penetrate the insulating layer and dig into the terminal. This is undesirable because it can cause a short circuit. For the above reasons, it has been difficult to reduce the seal width and make laminated batteries smaller.

[0007] Therefore, an object of the present disclosure is to provide a secondary battery that can improve structural efficiency. [Means for solving the problem]

[0008] As one aspect for solving the above-mentioned problems, the present disclosure provides a secondary battery comprising a power generating element and an exterior part that houses the power generating element, wherein the exterior part has a cylindrical part with openings on two opposing sides, inner lids that are placed on each opening, and a first resin that is placed so as to cover each opening and the opening-side surface of the inner lid, wherein the first resin is placed so as to fill the space between the cylindrical part and the inner lid, and the cylindrical part and the inner lid are integrated by the first resin.

[0009] The secondary battery may be in the following form: That is, the secondary battery may further include an electrode terminal connected to the power-generating element, the inner lid may have a surface disposed on the opening side of the cylindrical portion, a protruding portion protruding from the entire outer periphery of the surface toward the inside of the cylindrical portion, and a space surrounded by the protruding portion, at least one of the inner lids may have a through-hole on the surface, the electrode terminal may be disposed so as to pass through the through-hole, and a first resin disposed on the inner lid side through which the electrode terminal passes may further cover the outer periphery of at least a portion of the electrode terminal and fill the space between the through-hole and the electrode terminal, and the cylindrical portion, the inner lid, and the electrode terminal may be integrated with each other by the first resin.

[0010] The secondary battery may have the following configuration. That is, the exterior part may have a second resin filled therein, and the cylindrical part, inner lid, electrode terminals, and power generating element may be integrated with the second resin. Also, the power generating element may be wrapped in a resin film having insulating properties and water vapor barrier properties.

[0011] The cylindrical portion may be in the following form. That is, the cylindrical portion may be a cylindrical metal body or a metal laminate film formed into a cylindrical shape. Alternatively, the cylindrical portion may be composed of two U-shaped metal plates stacked upside down, with the ends of the metal plates overlapping on each of the opposing side surfaces of the cylindrical portion, and the cylindrical portion may have a third resin disposed to cover each of the side surfaces, and the ends of the overlapping metal plates may be integrated with the third resin. Alternatively, the cylindrical portion may be composed of a single metal plate, with the ends of the metal plates overlapping on one side surface of the cylindrical portion, and the cylindrical portion may have a third resin disposed to cover one of the side surfaces of the cylindrical portion, and the ends of the overlapping metal plates may be integrated with the third resin. [Effects of the Invention]

[0012] According to the secondary battery of the present disclosure, structural efficiency can be improved. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is a plan view of the secondary battery 100. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is a plan view of an example of a secondary battery in which a positive electrode terminal 31 and a negative electrode terminal 32 are arranged so as to protrude from the same surface in the width direction of an exterior part 20. [Figure 4] 1A is a plan view of the cylindrical portion 21. FIG. 1B is a cross-sectional view in the width direction. FIG. 1C is a side view of the cylindrical portion 21 as seen from the width direction. [Figure 5] 1(a) is a cross-sectional view of the vicinity of the opening 21a of the cylindrical portion 21 having protrusions 21b at each end of the thickness direction surface, and FIG. 1(b) is a cross-sectional view of the vicinity of the opening 21a of the cylindrical portion 21 having protrusions 21b bent inward. [Figure 6] (a) is a perspective view of the inner lid 22. (b) is a cross-sectional view taken along line bb in (a). (c) is a cross-sectional view taken along line cc in (a). [Figure 7] (a) is a cross-sectional view of the inner lid 22 having the taper 22e, and (b) is an example of use of the inner lid 22 having the taper 22e. [Figure 8] FIG. 1 is a comparison of longitudinal cross-sectional views of a conventional laminated battery (a) and a secondary battery 100 (b). [Figure 9] FIG. 1 is a plan view comparing a conventional laminated battery (a) and a secondary battery 100 (b). [Figure 10] FIG. 2 is a longitudinal cross-sectional view of a secondary battery 101. [Figure 11] FIG. 2 is a longitudinal cross-sectional view of a secondary battery 102. [Figure 12] FIG. 2 is a plan view of a power generating element 10 wrapped in a resin film 11. [Figure 13] 1(a) is a plan view of the cylindrical portion 121. FIG. 1(b) is a cross-sectional view of the cylindrical portion 121 in the width direction. [Figure 14] 1(a) is a plan view of the cylindrical portion 221. FIG. 1(b) is a cross-sectional view of the cylindrical portion 221 in the width direction. [Figure 15] 10 is a diagram showing one cooling mode of a secondary battery using a cylindrical portion 221. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] The secondary battery of the present disclosure will be described mainly using a secondary battery 100 as one embodiment. Fig. 1 shows a plan view of the secondary battery 100. Fig. 2 shows a cross-sectional view taken along line II-II in Fig. 1. In Figs. 1 and 2, the length direction of the secondary battery 100 is represented by x, the width direction of the secondary battery 100 is represented by y, and the thickness direction of the secondary battery 100 is represented by z. These directions are perpendicular to each other.

[0015] The secondary battery 100 includes a power generating element 10 and an exterior casing 20 that houses the power generating element 10. The secondary battery 100 also includes a positive terminal 31 and a negative terminal 32 (hereinafter, these may be collectively referred to as "electrode terminals 30") for connection to an external power source or a power load. The positive terminal 31 and the negative terminal 32 are arranged so as to protrude from different sides of the exterior casing 20 in the width direction. However, the arrangement positions of the positive terminal 31 and the negative terminal 32 are not limited thereto, and the positive terminal 31 and the negative terminal 32 may be arranged so as to protrude from the same side of the exterior casing 20 in the width direction. As an example, FIG. 3 shows a secondary battery in which the positive terminal 31 and the negative terminal 32 are arranged so as to protrude from the same side of the exterior casing 20 in the width direction.

[0016] <Power generation element 10> The power generating element 10 is formed by laminating a positive electrode current collecting foil, a positive electrode active material layer, an electrolyte layer, a negative electrode active material layer, and a negative electrode current collecting foil (hereinafter, these may be collectively referred to as "electrode elements"). The electrode elements are laminated in the thickness direction. There is no particular limit to the number of each electrode element to be laminated. The power generating element 10 in FIG. 2 has a configuration in which a plurality of these electrode elements are laminated. Furthermore, these electrode elements may be laminated so as to be electrically connected in series, or so as to be electrically connected in parallel.

[0017] The power generating element 10 in Fig. 2 has a sheet-like shape and is rectangular in plan view. However, the shape of the power generating element 10 is not particularly limited as long as it can be housed inside the exterior part 20. Furthermore, as shown in Fig. 2, each current collecting foil of the power generating element 10 may have tabs 11, 12 for connection to each electrode terminal 30. Tab 11 is provided on each positive current collecting foil and is electrically connected to positive terminal 31. Similarly, tab 12 is provided on each negative current collecting foil and is electrically connected to negative terminal 32.

[0018] The power generating element 10 may be subjected to a predetermined insulating treatment to prevent a short circuit due to contact with the cylindrical portion 21. For example, the power generating element 10 may be wrapped in an insulating film, an insulating sheet may be placed between the power generating element 10 and the cylindrical portion 21, or insulating tape may be attached to the inner surface of the power generating element 10 or the cylindrical portion 21. In this way, an insulating treatment may be performed in which a predetermined insulating layer is placed on the outer periphery of the power generating element 10.

[0019] The power generating element 10 and the cylindrical portion 23 may be in contact as long as either of them is insulated. In this case, the thickness of the inner lid terminal 22 may be thinner than the thickness of the power generating element 10 by the thickness of the first resin 23 filled between the cylindrical portion 21 and the inner lid terminal 22.

[0020] The power generating element 10 may be a solid-state battery or a liquid battery. A solid-state battery is preferable. The type of power generating element 10 is not particularly limited, and it may be a power generating element for a lithium-ion secondary battery or a power generating element for a sodium-ion secondary battery. The materials of the power generating element for a lithium-ion secondary battery are described below.

[0021] (Positive electrode current collecting foil, negative electrode current collecting foil) The positive electrode current collector foil and the negative electrode current collector foil are sheet-shaped metal foils. The metal constituting the positive electrode current collector foil and the negative electrode current collector foil is not particularly limited, but examples thereof include Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, stainless steel, etc. The metal constituting the positive electrode current collector foil is preferably Al. The material constituting the negative electrode current collector foil is preferably Cu.

[0022] The positive electrode current collector foil and the negative electrode current collector foil may have a coating layer (e.g., a carbon coating layer) on their surfaces to adjust the resistance. The thickness of the positive electrode current collector foil and the negative electrode current collector foil may be, for example, 0.1 μm or more and 1 mm or less.

[0023] (Cathode active material layer) The positive electrode active material layer is a sheet-like layer containing a positive electrode active material. The positive electrode active material is not particularly limited as long as it is a positive electrode active material that can be used in lithium-ion secondary batteries. Examples include various lithium-containing composite oxides such as lithium cobalt oxide, lithium nickel oxide, lithium manganate, lithium nickel cobalt manganate, and spinel-based lithium compounds.

[0024] The positive electrode active material layer may optionally contain a conductive additive or binder. The binder is not particularly limited as long as it is a binder that can be used in lithium ion secondary batteries. Examples include butadiene rubber (BR), butylene rubber (IIR), acrylate butadiene rubber (ABR), polyvinylidene fluoride (PVdF), etc. The conductive additive is not particularly limited as long as it is a conductive additive that can be used in lithium ion secondary batteries. Examples include carbon materials such as acetylene black and ketjen black, and metal materials such as nickel, aluminum, and stainless steel.

[0025] When the secondary battery 100 is an all-solid-state battery, the positive electrode active material layer may optionally contain a solid electrolyte. The solid electrolyte is not particularly limited as long as it is a solid electrolyte that can be used in a lithium ion secondary battery. For example, it may be an organic polymer electrolyte or an inorganic solid electrolyte. An inorganic solid electrolyte is preferred. This is because it has higher ionic conductivity and superior heat resistance compared to organic polymer electrolytes. The inorganic solid electrolyte may be an oxide solid electrolyte or a sulfide solid electrolyte. A sulfide solid electrolyte is preferred. Examples of oxide solid electrolytes include lithium lanthanum zirconate, LiPON, and Li 1+X AlXGe 2-X Examples of sulfide solid electrolytes include (PO4)3, Li-SiO-based glass, Li-Al-SO-based glass, etc. Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Si2S-P2S5, Li2S-P2S5-LiI-LiBr, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li2S-P2S5-GeS2, etc.

[0026] The content of each component in the positive electrode active material layer may be appropriately set depending on the purpose. The surface of the positive electrode active material may be coated with an oxide layer such as a lithium niobate layer, a lithium titanate layer, or a lithium phosphate layer. The thickness of the positive electrode active material layer may be, for example, 0.1 μm or more and 1 mm or less.

[0027] (Negative electrode active material layer) The negative electrode active material layer is a sheet-like layer containing a negative electrode active material. The negative electrode active material is not particularly limited as long as it is a negative electrode active material that can be used in lithium-ion secondary batteries. Examples include silicon and Si alloys, silicon-based active materials such as silicon oxide, carbon-based active materials such as graphite and hard carbon, various oxide-based active materials such as lithium titanate, metallic lithium, and lithium alloys.

[0028] The negative electrode active material layer may optionally contain a conductive additive or binder. The conductive additive and binder can be appropriately selected from conductive additives and binders that can be used in the positive electrode active material layer. Furthermore, when the secondary battery 100 is an all-solid-state battery, the negative electrode active material layer may optionally contain a solid electrolyte. The solid electrolyte can be appropriately selected from solid electrolytes that can be used in the positive electrode active material layer.

[0029] The content of each component in the negative electrode active material layer may be appropriately set depending on the purpose. The thickness of the negative electrode active material layer may be, for example, 0.1 μm or more and 1 mm or less.

[0030] (electrolyte layer) When the secondary battery 100 is an all-solid-state battery, the electrolyte layer is a sheet-shaped solid electrolyte layer. The solid electrolyte layer includes a solid electrolyte. The solid electrolyte can be appropriately selected from solid electrolyte layers that can be used in a positive electrode active material layer. The solid electrolyte layer may also optionally include a binder. The binder can be appropriately selected from binders that can be used in a positive electrode active material layer. The content of each component in the solid electrolyte layer may be appropriately set depending on the purpose. The thickness of the solid electrolyte layer may be, for example, 0.1 μm or more and 1 mm or less.

[0031] When the secondary battery 100 is a liquid battery, the electrolyte layer includes an electrolyte solution and a separator. The electrolyte solution and separator are not particularly limited as long as they are suitable for use in lithium-ion secondary batteries. Examples of the separator include porous sheets (films) made of polyolefins such as polyethylene (PE) and polypropylene (PP). The thickness of the separator may be, for example, 0.1 μm to 1 mm. The electrolyte solution typically contains a non-aqueous solvent and a supporting salt. Examples of the non-aqueous solvent include carbonates, ethers, esters, nitriles, sulfones, and lactones. Examples of the supporting salt include LiPF6, LiBF4, lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(trifluoromethane)sulfonimide (LiTFSI). The concentration of the supporting salt in the electrolyte is not particularly limited, but may be, for example, 0.5 mol / L to 5 mol / L. The electrolyte may also contain optional components such as a gas generating agent, a film forming agent, a dispersant, and a thickener.

[0032] <Exterior part 20> The exterior part 20 has a cylindrical part 21 having openings 21a on two opposing surfaces, inner lids 22 arranged in each opening 21a, and a first resin 23 arranged so as to cover each opening 21a and the opening-side surface 22a of the inner lid 22. The first resin 23 is arranged so as to fill the gap between the cylindrical part 21 and the inner lid 22, and the cylindrical part 21 and the inner lid 22 are integrated by the first resin 23.

[0033] (Cylindrical portion 21) The cylindrical portion 21 has a hollow shape with openings 21a on two opposing surfaces. The openings 21a are provided on both longitudinal surfaces of the cylindrical portion 21. The cross section of the cylindrical portion 21 in the width direction is rectangular. However, the cross section of the cylindrical portion is not limited to this. Figure 4(a) shows a plan view of the cylindrical portion 21, (b) shows a cross section in the width direction, and (c) shows a side view of the cylindrical portion 21 as viewed from the width direction.

[0034] The cylindrical portion 21 is made of a metal having a high water vapor barrier property from the viewpoint of preventing deterioration of the power generating element. For example, a metal having a high water vapor barrier property is a metal having a water vapor permeability of 1.0×10 -4 g / m 2 The lower the water vapor permeability, the higher the water vapor barrier properties. Examples of such metals include aluminum, stainless steel, SUS, and duralumin. From the viewpoints of lightness and workability, aluminum may be used as the material for the cylindrical portion 21. Another advantage of aluminum is that it is inexpensive.

[0035] The water vapor permeability can be measured by the cup method in accordance with JIS Z 0208 or by the gas chromatography method in accordance with JIS K 7129.

[0036] Here, the cylindrical portion 21 may be subjected to a predetermined insulating treatment to prevent short circuits due to contact with the power-generating element 10. For example, an insulating material such as an insulating resin sheet may be disposed between the power-generating element 10 and the cylindrical portion 21. The insulating material may be disposed, for example, between the thickness-wise surface of the power-generating element 10 and the cylindrical portion 21. This prevents electrical connection between the power-generating element 10 and the cylindrical portion 21 and prevents short circuits in the secondary battery 100. Alternatively, a metal laminate film (e.g., an aluminum laminate film) may be used in which at least the inner surface of the cylindrical portion 21 is covered with an insulating resin. This prevents electrical connection between the power-generating element 10 and the cylindrical portion 21 and prevents short circuits in the secondary battery 100 without the need for an insulating material. A metal laminate film is a multilayer body in which a resin (e.g., polypropylene, nylon, PET, etc.) is disposed on the surface of a metal layer. In this way, an insulating treatment may be performed to dispose a predetermined insulating layer on the inner periphery of the cylindrical portion 21.

[0037] However, the thickness of the metal layer of a metal laminate film is usually about 0.04 mm, which is relatively thin and therefore has the problem of low strength. Therefore, the cylindrical portion 21 is preferably made of a metal having a thickness of, for example, 0.05 mm to 0.2 mm, and more preferably 0.1 mm to 0.2 mm. Alternatively, a metal laminate film including a metal layer having a thickness within the above range may be used as the cylindrical portion 21. When a metal laminate film is used for the cylindrical portion 21, the metal laminate film is formed into a cylindrical shape.

[0038] The cylindrical portion 21 may have a protrusion 21b at an end in the length direction. Specifically, the cylindrical portion 21 may have a protrusion 21b on at least one of the thickness direction surface and the width direction surface at the end in the length direction. Providing the protrusion 21b serves to ensure an adhesive area with the first resin 23 and improve adhesive strength. The protrusion 21b refers to a portion that protrudes outward beyond the inner lid 22.

[0039] Fig. 5(a) shows a cross-sectional view of the vicinity of the opening 21a of the tubular portion 21, which has protrusions 21b at each end of the surface in the thickness direction. Fig. 5(b) shows a cross-sectional view of the vicinity of the opening 21a of the tubular portion 21, which has protrusions 21b bent inward.

[0040] The cylindrical portion 21 shown in FIG. 5(a) has protrusions 21b at each end of its thickness-direction surface. That is, the cylindrical portion 21 has a structure in which the end of its thickness-direction surface protrudes more than the end of its width-direction surface. As shown in FIG. 5(a), the protrusions 21b of the cylindrical portion 21 increase the adhesion area with the first resin 23, thereby improving adhesive strength. In other words, peeling of the first resin 23 can be suppressed. Peeling of the first resin 23 is undesirable because it would make it impossible to ensure water vapor barrier properties. Furthermore, as shown in FIG. 5(b), the protrusions 21b may be bent toward the inside of the cylindrical portion 21. This facilitates positioning of the inner lid 22. In this case, the opening formed by the two protrusions 21 becomes the opening 21a. The angle between the protrusions 21b and the surface of the cylindrical portion 21 (the surface having the protrusions 21b) is not particularly limited and can be any angle between 0° and 180°. Preferably, it is between 15° and 135°. The length of the protrusion 21b is not particularly limited, but is in the range of 0.5 mm to 2 mm, for example.

[0041] (Inner lid 22) The inner lids 22 are disposed in the respective openings 21a of the cylindrical portion 21. The inner lids 22 have a rectangular outer peripheral shape. However, the outer peripheral shape of the inner lids 22 is not particularly limited as long as it has a shape that conforms to the cross-sectional shape of the cylindrical portion 21 in the width direction. Fig. 6(a) shows a perspective view of the inner lid 22, (b) shows a cross-sectional view taken along line bb in (a), and (c) shows a cross-sectional view taken along line cc in (a).

[0042] The inner lid 22 has a surface 22a disposed on the opening 21a side of the cylindrical portion 21, a protruding portion 22b protruding from the entire outer periphery of the surface 22a toward the inside of the cylindrical portion 21, and a space 22c surrounded by the protruding portion 22b. The space 22c opens toward the inside of the cylindrical portion 21.

[0043] The "protruding portion 22b protruding from the entire outer periphery of the surface 22a toward the inside of the tubular portion 21" refers to portions protruding from both ends of the surface 22a in the thickness direction and both ends of the surface 22a in the width direction toward the inside of the tubular portion 21, and these portions are connected to each other at the corners of the surface 22a. In other words, the protruding portion 22b is a member protruding from the entire outer periphery of the surface 22a. The length L1 of the protruding portion 22b is not particularly limited, but it is sufficient that the length L1 exhibits sufficient water vapor barrier properties when the tubular portion 21 and the inner lid 22 are integrated with the first resin 23. For example, it may be 0.5 mm or more and 3 mm or less.

[0044] The surface 22a of the inner lid 22 has a through hole 22d, and the electrode terminal 30 (positive terminal 31 or negative terminal 32) is disposed so as to pass through the through hole 22d. When the electrode terminals 30 are disposed on different surfaces of the exterior part 20 in the width direction as shown in FIG. 1, both inner lids 22 have the through hole 22d. On the other hand, when the electrode terminals 30 are disposed on the same surface of the exterior part 20 in the width direction as shown in FIG. 3, it is sufficient that at least one of the inner lids 22 (the inner lid 22 on which the electrode terminal 30 is disposed) is provided with the through hole 22d. In this case, two through holes 22d may be provided so that each electrode terminal 30 is disposed therein. Alternatively, each electrode terminal 30 may be disposed in one through hole 22d.

[0045] The inner lid 22 may consist of one member, or two or more members. From the viewpoint of easily arranging the electrode terminal 30, the inner lid 22 may consist of two members cut so as to divide the length in the thickness direction so as to include the through-hole 22c. The inner lid 22 may also have a tapered portion 22e between the surface 22a and the protruding portion 22b. As an example, FIG. 7(a) shows a cross-sectional view of the inner lid 22 having the tapered portion 22e, and FIG. 7(b) shows an example of use of the inner lid 22 having the tapered portion 22e.

[0046] The inner lid 22 may be made of a material with high water vapor barrier properties from the viewpoint of preventing deterioration of the power generating element. A material with high water vapor barrier properties is, for example, a material with a water vapor permeability of 1.0×10 -4 g / m 2A material with a life of less than 24 hours. Such materials include, for example, metal and glass. From the viewpoint of workability, metal may be used as the material for the inner lid 22. Examples of metal include aluminum, stainless steel, SUS, and duralumin. From the viewpoint of lightness and workability, aluminum may be used as the material for the inner lid 22. Another advantage of aluminum is that it is inexpensive.

[0047] Here, if the inner lid 22 is made of metal, a predetermined insulation treatment may be performed to prevent short circuits due to contact between the inner lid 22 and the power generating element 10, the cylindrical portion 21, and the electrode terminal 30. For example, to prevent short circuits due to contact between the inner lid 22 and the power generating element 10, an insulating material such as an insulating resin sheet may be disposed between the inner lid 22 and the power generating element 10. This prevents electrical connection between the power generating element 10 and the inner lid 22 and prevents short circuits in the secondary battery 100. Furthermore, to prevent short circuits due to contact between the inner lid 22 and the cylindrical portion 21, a laminated metal may be used in which at least the inner surface of the cylindrical portion 21 is covered with an insulating resin. This prevents electrical connection between the power generating element 10 and the cylindrical portion 21 and prevents short circuits in the secondary battery 100 without the need for an insulating material. Furthermore, to prevent short circuits due to contact with the cylindrical portion 21, the outer periphery of the inner lid 22 may be wrapped in an insulating film, or insulating tape may be attached to the outer periphery of the inner lid 22. In this way, an insulating process may be performed by disposing a predetermined insulating layer on the outer periphery of the inner lid 22. Furthermore, in order to prevent a short circuit due to contact between the inner lid 22 and the electrode terminal 30, an insulating process may be performed by disposing a predetermined insulating layer on either the through hole 22d or the electrode terminal 30.

[0048] (First resin 23) The first resin 23 is arranged so as to cover each opening 21a and the surface 22a of the inner lid 22 facing the opening. The first resin 23 is also arranged so as to fill the space between the cylindrical portion 21 and the inner lid 22, and the cylindrical portion 21 and the inner lid 22 are integrated by the first resin 23. When an electrode terminal 30 is arranged in the inner lid 22, the first resin 23 is also arranged so as to cover at least a portion of the outer periphery of the electrode terminal 30 and to fill the space between the through-hole 22d and the electrode terminal 30. The cylindrical portion 21, the inner lid 22, and the electrode terminal are integrated by the first resin 23. This allows the secondary battery 100 to ensure sufficient water vapor barrier properties.

[0049] As shown in FIG. 2 , the first resin 23 covers the opening 21 a and the surface 22 a of the inner lid 22 facing the opening 21 a, and also fills the gap between the tubular portion 21 and the inner lid 22. The "gap between the tubular portion 21 and the inner lid 22" refers to the gap between the inner surface of the tubular portion 21 and the outer periphery of the inner lid 22. The opening 21 a covered by the first resin 23 refers to the surface of the gap facing the opening 21 a. To form such a gap, the inner lid 22 is preferably made slightly smaller than the outer shape of the tubular portion 21. By disposing the first resin 23 as described above, the tubular portion 21 and the inner lid 22 are integrated by the first resin 23. While it is sufficient for the first resin 23 to fill at least a portion of the gap between the tubular portion 21 and the inner lid 22, it is preferable to fill the entire gap as shown in FIG. 2 from the viewpoint of ensuring water vapor barrier properties. However, as described below, when filling the inside of the tubular portion 21 with the second resin 24, the second resin 24 may be placed in addition to the first resin 23 in the gap formed between the tubular portion 21 and the inner lid 22.

[0050] Furthermore, the first resin 23 covers the entire outer periphery of at least a portion of the electrode terminal 30 and fills the gap between the electrode terminal 30 and the through hole 22d. "The entire outer periphery of at least a portion of the electrode terminal 30" refers to the entire outer periphery of a region of a predetermined length extending outward from the surface 22a of the electrode terminal 30. The predetermined length is length L2 in FIG. 2. "The gap between the electrode terminal 30 and the through hole 22d" refers to the gap between the outer periphery of the electrode terminal 30 and the inner surface of the through hole 22d. To form such a gap, it is preferable to make the through hole 22d slightly larger than the electrode terminal 30. By disposing the first resin 23 as described above, the inner lid 22 and the electrode terminal 30 are integrated by the first resin 23.

[0051] In this way, the exterior part 20 fills the paths (gaps) through which water vapor penetrates from the outside to the inside with the first resin 23, and therefore can sufficiently prevent water vapor from penetrating into the interior of the exterior part 20. In other words, this means that the exterior part 20 may have gaps through which water vapor can penetrate between the tubular part 21 and the inner lid 22 and between the electrode terminal 30 and the through-hole 22. Because such gaps are filled with the first resin 23, the tubular part 21 and the inner lid 22 do not need to be designed strictly.

[0052] Here, "integration" means that the materials are bonded with resin and integrated to the extent that they can be recognized as a single component. "Integration" using the first resin can be achieved by placing an intermediate member, which includes the cylindrical portion 21 housing the power generating element 10 and the inner lid 22 disposed in the opening 21a of the cylindrical portion 21, in a predetermined mold, and then injecting the first resin into the mold and allowing it to harden. In this way, the exterior body 20 can be manufactured by integral molding using the first resin 23.

[0053] Here, as shown in Figure 7(b), if the inner lid 22 has a tapered portion 22e, the first resin 23 can enter between the tapered portion 22e and the tubular portion 21, thereby increasing the adhesive area between the first resin 23 and the inner lid 22 and improving the adhesive strength between these components.

[0054] The length L2 from the end of the first resin 23 to the surface 22a of the inner lid 22 on the opening side is not particularly limited, but may be in the range of 0.5 mm or more and 2 mm or less in consideration of the water vapor barrier property.

[0055] In this way, the secondary battery 100 uses the exterior 20 to seal the power generating element 10 instead of a conventional laminate exterior body, thereby providing water vapor barrier properties equivalent to or superior to those of conventional laminate exterior bodies. Furthermore, with conventional laminate exterior bodies, sealing defects can occur when the power generating element is housed inside and its edges are heat-sealed. In such cases, water vapor can enter through the defective sealing, making it impossible to ensure water vapor barrier properties. In contrast, the secondary battery 100 uses the first resin 23 to seal the power generating element 10 inside the exterior 20, making sealing defects extremely unlikely to occur. Therefore, there is no need to conduct a water vapor barrier property test (leak test) after the secondary battery 100 is manufactured.

[0056] From the viewpoint of preventing deterioration of the power generating element, a resin having water vapor barrier properties is used as the first resin 23. The resin having water vapor barrier properties is, for example, a resin having a water vapor permeability of 1.0×10 -4 g / m 2 24 hours or more 50 x 10 -4 g / m 2 The resin is a resin having a life of 24 hours or less. The type of such resin is not particularly limited, but examples thereof include thermoplastic resins. Examples of thermoplastic resins include polypropylene and polyester.

[0057] <Electrode terminal 30> The electrode terminal 30 includes a positive electrode terminal 31 and a negative electrode terminal 32, and is electrically connected to the power generating element 10. Specifically, the positive electrode terminal 31 is electrically connected to the positive electrode current collector foil (tab 11), and the negative electrode terminal 32 is electrically connected to the negative electrode current collector foil (tab 12). The connection method is not particularly limited, and the electrode terminal and the current collector foil may be joined using ultrasonic waves, for example.

[0058] As described above, the electrode terminal 30 is disposed so as to penetrate the through-hole 22d of the inner lid 22 and protrudes outward from the opening 21a. The first resin 23 covers the entire outer periphery of at least a portion of the electrode terminal 30 and fills the gap between the electrode terminal 30 and the through-hole 21, thereby integrating the inner lid 22 and the electrode terminal with the first resin 23.

[0059] The material of the electrode terminal 30 is not particularly limited, and can be appropriately selected from metals that can be used for current collector foils.

[0060] <Structural efficiency> Next, the structural efficiency achieved by the secondary battery 100 will be described. Figures 8 and 9 show a comparison between a conventional laminated battery and the secondary battery 100. Figure 8 is a comparison of longitudinal cross-sectional views of the conventional laminated battery (a) and the secondary battery 100 (b). Figure 9 is a comparison of plan views of the conventional laminated battery (a) and the secondary battery 100 (b).

[0061] As shown in Figure 8(a), a conventional laminated battery has a terminal portion (region A) protruding from the laminated outer casing, a heat-sealed portion (region B) where the laminated outer casing is heat-sealed, a joint portion (region C) where the electrode terminal and the current collecting foil are joined, and a current collecting foil portion (region D) where multiple current collecting foils connected to the power generating element are present.

[0062] As shown in FIG. 8(b), the length of the portions of the secondary battery 100 corresponding to regions A and D is equivalent to that of a conventional laminated battery. On the other hand, by using the exterior part 20, the length of the portions of the secondary battery 100 corresponding to regions B and C can be made shorter than that of a conventional laminated battery. Specifically, this is as follows.

[0063] First, we explain why the length of the portion corresponding to region B is shortened. Region B (seal width) in conventional laminated batteries typically needs to be set to a length greater than 3 mm. This is due to the following reasons: (1) A short seal width can prevent proper heat welding, resulting in poor sealing. (2) Because the laminate exterior body is not very rigid, a short seal width can cause the adhesive in the seal area to peel off due to external impact, resulting in the adhesive surface being insufficient. (3) During heat welding, if the terminal is not parallel to the adhesive surface of the laminate exterior body, a short seal width weakens the corrective force to return the inclination to its original position, preventing proper heat welding and increasing the likelihood of poor sealing. (4) During heat welding, a short seal width increases the pressure per area applied to the seal area by the heat welding head, which can cause the metal layer inside the laminate exterior body to penetrate the insulating layer and dig into the terminal. This is undesirable because it can cause a short circuit.

[0064] On the other hand, the secondary battery 100 uses an exterior part 20 in which the cylindrical part 21 and the inner lid 22 are integrated with a first resin 23. This integration with the first resin 23 significantly reduces poor adhesion between the cylindrical part 21 and the inner lid 22. Furthermore, proper adhesion is possible even when the inner lid 22 is tilted and the gap between the cylindrical part 21 and the inner lid 22 is not parallel. Furthermore, because thermal welding is not performed, short circuits rarely occur. Furthermore, integration with the first resin 23 ensures rigidity, thereby preventing peeling of the adhesive. Therefore, the length (L1 + L2) of the portion of the secondary battery 100 corresponding to region B of a conventional laminated battery can be set to 3 mm or less. It may also be 2 mm or less. Therefore, the width of the portion of the secondary battery 100 corresponding to region B can be made shorter than that of a conventional laminated battery.

[0065] Next, the reason why the length of the portion corresponding to region C is shortened will be explained. As shown in FIG. 8, the inner lid 22 of the secondary battery 100 has a space 22c inside the protrusion 22b, and the electrode terminal 30 and the current collecting foil are joined in the space 22c. In this way, the secondary battery 100 can effectively utilize the space 22c of the inner lid 22. Therefore, in the secondary battery 100, the length of the portion corresponding to region C can be shortened in appearance. Also, as shown in FIG. 8(b), the secondary battery 100 can also fulfill the roles of regions B and C in one region. This allows the secondary battery 100 to have a more efficient structure than conventional laminated batteries.

[0066] Next, we will explain Figure 9. As shown in Figure 9, conventional laminated batteries require heat-sealed sections S on up to four sides of the outer periphery. In contrast, as described above, the structural efficiency of the secondary battery 100 is improved by the exterior section 20 at both ends in the length direction. Furthermore, because the secondary battery 100 uses the cylindrical section 21, which is a cylindrical metal body, heat-sealed sections are not required on both sides in the width direction. Therefore, the secondary battery 100 has a structural efficiency in this respect. Furthermore, the absence of heat-sealed sections on both sides in the width direction also improves the water vapor barrier property.

[0067] As described above, the secondary battery 100 has a significantly improved structural efficiency compared to conventional laminated batteries.

[0068] Here, we will explain the advantages of the secondary battery 100 compared to a secondary battery in which the power generating element is sealed using a laminated exterior body and an inner lid. By placing the inner lid over the opening of the cylindrical laminated exterior body and thermally welding the laminated exterior body to the outer surface of the inner lid, it is believed that the secondary battery's structural efficiency can be improved compared to conventional laminated batteries. This is because the internal space of the inner lid can be utilized. However, because the laminated exterior body and the inner lid are bonded by thermal welding, it is difficult to reduce the seal width to 3 mm or less. Specifically, this is due to the following reasons: (1) A short seal width may result in poor sealing. (2) Because the laminated exterior body is not very rigid, a short seal width may cause the adhesive in the sealed area to peel off due to external impact, resulting in the adhesive surface not being maintained. (3) Furthermore, when the inner lid tilts due to external impact, the ability to return the tilt to its original position is weakened, which may result in the adhesive surface not being properly maintained. (4) During thermal welding, if the outer surface of the inner lid is not parallel to the welded surface of the laminated exterior body, a short seal width weakens the ability to correct the tilt, increasing the likelihood of poor sealing. Furthermore, if the laminated exterior body is formed into a cylindrical shape, a sealing area may be required on the side. For these reasons, the secondary battery 100 has improved structural efficiency compared to secondary batteries that combine a laminated exterior body and an inner lid.

[0069] There are also advantages in manufacturing. When heat welding the laminated exterior body and the outer circumferential surface of the inner lid, there is a problem that the inner lid cannot be held down from the inside, making the heat welding difficult. On the other hand, in the secondary battery 100, these components can be integrated by placing the tubular portion 21 and the inner lid 22 in a predetermined mold and filling it with the first resin 23, so this problem does not arise. Furthermore, because the power generating element 10 is accommodated in the tubular portion 21 and then integrated in the predetermined mold, the assembly of each component is easier and the dimensional accuracy is better than when a laminated exterior body is used.

[0070] <Prevention of Short Circuit Between the Power-Generating Element 10 and the Exterior Part 20> When the cylindrical portion 21 and the inner lid 22 are made of metal, an insulating material may be disposed between the power generating element 10 and these members, as described above, in order to prevent a short circuit due to contact between the power generating element 10 and these members. Specific embodiments for disposing the insulating material will be described below.

[0071] First, a description will be given of a secondary battery 101 in which the inside of the exterior part 20 is filled with the second resin 24. Fig. 10 shows a longitudinal cross-sectional view of a secondary battery 101 in which the entire inside of the exterior part 20 is filled with the second resin 24.

[0072] As shown in FIG. 10 , the exterior part 20 has a second resin 24 filled therein. The second resin 24 can be the same resin as the first resin 23. In FIG. 10 , the second resin 24 is disposed throughout the interior of the exterior part 20, but this is not limited thereto and it is sufficient that the second resin 24 is disposed in a position where the power generating element 10 and the exterior part 20 can come into contact with each other. Preferably, the second resin 24 is disposed throughout the interior of the exterior part 20.

[0073] In this way, by providing the exterior part 20 with the second resin 24 inside, the tubular part 21, the inner lid 22, the electrode terminals 30, and the power-generating element 10 can be integrated with the second resin 24. This makes it possible to suppress short circuits caused by contact between the power-generating element 10 and the exterior part 20. For example, even if a predetermined insulating layer is disposed on the power-generating element 10 or the exterior part 20, there is a risk that the insulating layer will be broken by an external impact, causing contact between the power-generating element 10 and the exterior part 20 and resulting in a short circuit. In contrast, by disposing the second resin 24 inside the exterior part 20, it is possible to more effectively suppress contact between the power-generating element 10 and the exterior part 20 than when only an insulating layer is disposed, thereby suppressing short circuits in the battery.

[0074] Furthermore, the secondary battery 100 can further improve its water vapor barrier properties by including the second resin 24. Furthermore, by integrating the various components with the second resin 24, movement of the power generating element 10 due to external impact can be suppressed, thereby suppressing breakage of the current collecting foil and tabs 11 and 12 due to movement of the power generating element 10. In addition, chipping or slipping off of the power generating element 10 due to external impact can also be suppressed.

[0075] The method for filling the interior of the exterior part 20 with the second resin 24 is not particularly limited. For example, holes for injecting the second resin 24 may be formed in predetermined locations of the tubular part 21 and / or the inner lid 22. The shape of the holes is not particularly limited and may be circular, elliptical, or rectangular. At least one hole may be formed in the tubular part 21, and at least one hole may be formed in the inner lid 22. For example, as shown in FIG. 4(c), multiple holes 21c and 21d of different shapes may be formed in the side surface of the tubular part 21. Furthermore, as shown in FIG. 6(a), multiple holes 22f may be formed in the surface 22a of the inner lid 22. Note that when a power generating element for a liquid battery is used as the power generating element, a predetermined electrolyte may be injected through the holes after the second resin 24 has been filled.

[0076] Next, a secondary battery 102 in which the power generating element 10 is wrapped in a resin film 13 having insulating properties and water vapor barrier properties will be described. Fig. 11 shows a longitudinal cross section of the secondary battery 102 in which the power generating element 10 is wrapped in the resin film 13. Fig. 12 shows a plan view of the power generating element 10 wrapped in the resin film 13.

[0077] As shown in FIGS. 11 and 12 , the resin film 13 has a cylindrical shape and has an opening on the side where the electrode terminal 30 is disposed. The resin film 13 encases the entire power generating element 10. In FIG. 12 , components disposed inside the resin film 13 are indicated by dotted lines. The resin film 13 may encase at least a portion of the electrode terminal 30 in addition to the power generating element 10. For example, as shown in FIG. 11 , an end of the resin film 13 may pass through the through-hole 22d of the inner lid 22 and encase the electrode terminal 30 disposed inside the first resin 23. This allows the resin film 13 to be fixed by the first resin 23. Enclosing the entire power generating element 10 with the resin film 13 in this manner can prevent short circuits due to contact between the power generating element 10 and the exterior casing 20. Furthermore, the inclusion of the resin film 13 in the secondary battery 100 can further improve the water vapor barrier property.

[0078] The resin film 13 may be any resin film having insulating properties and water vapor barrier properties. For example, it may be a resin film on which aluminum or silica is vapor-deposited. The type of resin is not particularly limited, but examples thereof include polypropylene and polyethylene terephthalate.

[0079] Alternatively, the power generating element 10 may be wrapped in the resin film 13 and the inside of the exterior part 20 may be filled with the second resin 24 .

[0080] <Other forms of the cylindrical portion> From the viewpoint of structural efficiency, the cylindrical portion 21 may be a cylindrical metal body or a metal laminate film formed into a cylindrical shape, as shown in FIG. 3 . A cylindrical metal body is preferable. However, such a cylindrical portion has the problem that it is difficult to accommodate the power generating element 10 inside. Therefore, the following cylindrical portions 121 and 221, which make it easier to accommodate the power generating element 10, may be used.

[0081] First, the cylindrical portion 121 will be described. FIG. 13(a) shows a plan view of the cylindrical portion 121, and FIG. 13(b) shows a widthwise cross-sectional view of the cylindrical portion 121. As shown in FIG. 13, the cylindrical portion 121 is composed of two metal plates 121a and a third resin 121d. The metal plates 121a are U-shaped members each having a bottom surface 121b and protruding portions 121c protruding in the same direction from opposing ends of the bottom surface 121b. As shown in FIG. 13(b), the two metal plates 121a are stacked upside down, and the protruding portions 121c of the two metal plates 121a are stacked on each other on the opposing side surfaces (widthwise surfaces) of the cylindrical portion 121. A third resin 121c is then disposed to cover each side surface of the cylindrical portion 121. Specifically, third resin 121c entirely covers the side surfaces of protruding portions 121c of overlapping metal plates 121a and fills gaps between protruding portions 121c of overlapping metal plates 121a, thereby integrating the ends of overlapping metal plates 121a with third resin 121c.

[0082] Because the cylindrical portion 121 includes two metal plates 121a, the power generating element 10 is placed inside one of the metal plates 121a, and then the other metal plate 121a is placed on top of it upside down, and the protruding portions 121c of the metal plate 121a are integrated with the third resin 121d to form the cylindrical portion 121. In this way, by using the cylindrical portion 121, the power generating element 10 can be easily accommodated inside the cylindrical portion 121.

[0083] Next, the cylindrical portion 221 will be described. FIG. 14(a) shows a plan view of the cylindrical portion 221, and FIG. 14(b) shows a widthwise cross-sectional view of the cylindrical portion 221. As shown in FIG. 14, the cylindrical portion 221 is composed of one metal plate 221a and a third resin 221d. The metal plate 221a is formed into a cylindrical shape, and the end 221b of the metal plate 221a overlaps with one side surface of the cylindrical portion 221. The third resin 221c is arranged so as to cover the side surface where the end 221b overlaps. Specifically, the third resin 221c entirely covers the side surface of the overlapping end 221b and fills the gap between the end 221b of the overlapping metal plate 221a. As a result, the end 221b of the overlapping metal plate 221a is integrated with the third resin 221c.

[0084] Because the cylindrical portion 221 is made of a single metal plate 121a, the cylindrical portion 221 can be fabricated by placing the power generating element 10 inside the cylindrical metal plate 221a and then integrating the end portion 221b with the third resin 121c. In this way, by using the cylindrical portion 221, the power generating element 10 can be easily housed inside the cylindrical portion 221. Furthermore, as shown in FIG. 15 , the secondary battery can be easily cooled by bringing the side of the cylindrical portion 221 where the third resin 221c is not arranged into contact with a predetermined cooling unit X. Note that this type of cooling can also be applied to a secondary battery using the cylindrical portion 21.

[0085] The metal plate used in the above two embodiments may be a simple metal plate or a metal laminate film. A metal plate is preferable. The type of metal may be a metal with high water vapor barrier properties. The third resin used in the above two embodiments may be the same resin as the first resin 23. Furthermore, "integration" using the third resin can be achieved by placing the overlapping metal plates 121a or the cylindrically formed metal plate 221a in a predetermined mold, and injecting the third resin into the mold and allowing it to harden. This allows the cylindrical portions 121 and 221 to be manufactured.

[0086] The secondary battery of the present disclosure has been described above mainly using the secondary battery 100 as one embodiment. As described above, the secondary battery of the present disclosure can achieve structural efficiency. The secondary battery of the present disclosure can be used for any purpose. For example, the secondary battery of the present disclosure can be used as an in-vehicle secondary battery. [Explanation of symbols]

[0087] 10 Power generation elements Tabs 11 and 12 13 Resin film 20 Exterior part 21, 121, 122 Cylindrical part 21a opening 21b Projection 21c hole 21d hole 22 Inner lid 22a side 22b Projection 22c space 22d through hole 22e Tapered section 22f hole 23 First Resin 24 Second Resin 30 electrode terminal 31 Positive terminal 32 Negative terminal 100, 101, 102 secondary battery 121a, 221a metal plate 121b Bottom 121c Protrusion 121d, 221c Third Resin 221b End

Claims

[Claim 1] a power generating element and an exterior part that houses the power generating element; the exterior part has a cylindrical part having openings on two opposing surfaces, inner lids arranged on the openings, and a first resin arranged to cover the openings and the opening-side surfaces of the inner lids; the first resin is disposed so as to fill a space between the cylindrical portion and the inner lid, The power generating element is wrapped in a resin film that has insulating and water vapor barrier properties. Secondary battery.

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