Secondary batteries

Abstract

To provide a rechargeable battery with a compact configuration yet high capacity. [Solution] A secondary battery according to one embodiment of the present disclosure comprises a battery element having a first electrode and a second electrode, and an outer casing member housing the battery element. The outer casing member includes a cylindrical wall portion having a laminated structure in which an adhesive resin layer, a metal foil, and a resin film are laminated in this order from the inside out, including a first open end, and a first electrode terminal plate joined to the adhesive resin layer at the first open end of the cylindrical wall portion. The thickness of the first portion of the adhesive resin layer sandwiched between the first electrode terminal plate and the metal foil is thinner than the thickness of the third portion of the adhesive resin layer excluding the first portion.

Description

Technical Field

[0001] The present disclosure relates to secondary batteries.

Background Art

[0002] Due to the widespread use of various electronic devices such as mobile phones, the development of secondary batteries is underway as a power source that is small and lightweight and can obtain a high energy density. This secondary battery includes a positive electrode, a negative electrode, and an electrolyte housed inside an exterior member, and various studies have been made on the configuration of the secondary battery (see, for example, Patent Document 1).

[0003] For example, Patent Document 1 describes a sealed power storage device including an electrode body in which a positive electrode body and a negative electrode body are laminated or wound via a separator, and an exterior case that houses the electrode body.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Various studies have been made to improve the performance of secondary batteries. However, there is still room for improvement in the performance of secondary batteries.

[0006] Therefore, it is desirable to provide a secondary battery having a high capacity while having a compact configuration.

Means for Solving the Problems

[0007] A secondary battery according to one embodiment of the present disclosure comprises a battery element having a first electrode and a second electrode, and an outer casing member housing the battery element. The outer casing member includes a cylindrical wall portion having a laminated structure in which an adhesive resin layer, a metal foil, and a resin film are laminated in that order from the inside out, including a first open end, and a first electrode terminal plate joined to the adhesive resin layer at the first open end of the cylindrical wall portion. The thickness of the first portion of the adhesive resin layer sandwiched between the first electrode terminal plate and the metal foil is thinner than the thickness of the third portion of the adhesive resin layer excluding the first portion. [Effects of the Invention]

[0008] According to one embodiment of the secondary battery of this disclosure, the outer casing includes a cylindrical wall portion having a laminated structure of metal foil and resin film, thus providing a configuration suitable for miniaturization and weight reduction while maintaining the size of the battery element. Therefore, the secondary battery of one embodiment of this disclosure has a compact configuration while having a high capacity.

[0009] Furthermore, the effects of this disclosure are not necessarily limited to those described herein, but may include any of the series of effects related to this technology described later. [Brief explanation of the drawing]

[0010] [Figure 1A] Figure 1A is a perspective view showing the configuration of a secondary battery as one embodiment of the present disclosure. [Figure 1B] Figure 1B is an exploded perspective view of the secondary battery shown in Figure 1A. [Figure 2] Figure 2 is a vertical cross-sectional view showing the cross-sectional configuration of the secondary battery shown in Figure 1A. [Figure 3] Figure 3 is an enlarged cross-sectional view showing a magnified view of a portion of the cross-sectional structure of the secondary battery shown in Figure 2. [Figure 4] Figure 4 is a partial cross-sectional view showing the configuration of the battery element shown in Figure 2. [Figure 5] Figure 5 is an enlarged cross-sectional view showing a magnified view of a portion of the cross-sectional configuration of the secondary battery of the first modified example. [Figure 6]FIG. 6 is an enlarged cross-sectional view showing an enlarged partial cross-sectional configuration of the secondary battery of the second modification. [Figure 7] FIG. 7 is an enlarged cross-sectional view showing an enlarged partial cross-sectional configuration of the secondary battery of the third modification. [Figure 8] FIG. 8 is an enlarged cross-sectional view showing an enlarged partial cross-sectional configuration of the secondary battery of the fourth modification.

MODE FOR CARRYING OUT THE INVENTION

[0011] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. The order of description is as follows. 1. One Embodiment 1-1. Configuration 1-2. Operation 1-3. Manufacturing Method 1-4. Action and Effect 2. Modifications of One Embodiment 2-1. First Modification 2-2. Second Modification 2-3. Third Modification 2-4. Fourth Modification

[0012] <1. One Embodiment> First, a secondary battery according to an embodiment of the present disclosure will be described.

[0013] The secondary battery described here has an appearance of a flat and columnar three-dimensional shape and is called a so-called coin type, button type, etc. As will be described later, this secondary battery has a pair of bottom portions facing each other and a side wall portion located between the pair of bottom portions. In this secondary battery, the height is smaller than the outer diameter. The "outer diameter" here is the maximum diameter (maximum outer diameter) of the bottom portion. In this secondary battery, the maximum diameters of each of the pair of opposing bottom portions are substantially equal to each other. Also, the "height" here is the maximum distance from the upper surface of one bottom portion to the lower surface of the other bottom portion. In the present embodiment, the direction in which the pair of bottom portions face each other is defined as the height direction Z.

[0014] The charge-discharge principle of the secondary battery is not particularly limited. Hereinafter, the case where the battery capacity is obtained by utilizing the occlusion and release of electrode reactants will be described. This secondary battery includes an electrolyte together with a positive electrode and a negative electrode. In this secondary battery, in order to prevent the deposition of electrode reactants on the surface of the negative electrode during charging, the charging capacity of the negative electrode is larger than the discharging capacity of the positive electrode. That is, the electrochemical capacity per unit area of the negative electrode is set to be larger than the electrochemical capacity per unit area of the positive electrode. Note that the secondary battery of the present embodiment is a secondary battery with a high charging voltage specification that can exhibit good cycle characteristics without reducing the energy density even when charged at a high voltage of 4.38 V or more.

[0015] The type of the electrode reactant is not particularly limited, but specifically, it is a light metal such as an alkali metal and an alkaline earth metal. The alkali metals are lithium, sodium, and potassium and the alkaline earth metals are beryllium, magnesium, calcium, and the like.

[0016] Hereinafter, the case where the electrode reactant is lithium will be taken as an example. A secondary battery in which the battery capacity is obtained by utilizing the occlusion and release of lithium is a so-called lithium-ion secondary battery. In this lithium-ion secondary battery, lithium is occluded and released in an ionic state.

[0017] [[ID=1**6**]](1-1. Configuration) FIG. 1A shows a perspective configuration of the secondary battery of the present embodiment. FIG. 1B shows the configuration of the secondary battery shown in FIG. 1A disassembled. FIG. 2 shows a vertical cross-sectional configuration along the height direction of the secondary battery shown in FIG. 1A. FIG. 3 shows an enlarged view of a partial vertical cross-section of the secondary battery shown in FIG. 2. However, in FIG. 3, only some components are shown.

[0018] For convenience, in the following explanation, the upper side of the paper in Figure 1 and Figure 2 will be described as the upper side of the secondary battery, and the lower side of the paper in Figure 1 and Figure 2 will be described as the lower side of the secondary battery.

[0019] The secondary battery described here has a three-dimensional shape in which the height H is smaller than the outer diameter D, as shown in Figure 1A; that is, a flat and columnar three-dimensional shape. The three-dimensional shape of the secondary battery shown in Figure 1A is flat and cylindrical. In this embodiment, the vertical direction of the paper in Figures 1A, 1B, and 2 is defined as the height direction Z. Therefore, the height H represents the dimension in the height direction Z of the secondary battery in this embodiment. The outer diameter D represents the dimension in the direction perpendicular to the height direction Z of the secondary battery in this embodiment.

[0020] The dimensions of a secondary battery are not particularly limited, but as an example, the outer diameter D is 3mm to 30mm and the height H is 0.5mm to 70mm. However, the ratio of the outer diameter D to the height H (D / H) is greater than 1. That is, the outer diameter D is greater than the height H. There is no particular upper limit to this ratio (D / H), but it is preferably 25 or less.

[0021] As shown in Figures 1A, 1B, and 2, this secondary battery comprises an outer casing 10, a battery element 40, a positive electrode lead 51, a negative electrode lead 52, and insulating films 62 and 63.

[0022] [Exterior components] As shown in Figures 1A, 1B, and 2, the exterior member 10 is a hollow structure having an internal space V for housing the battery element 40 and the like.

[0023] In the configuration example shown in Figure 1, the exterior member 10 has a flat and substantially cylindrical outer shape, corresponding to the three-dimensional shape of the secondary battery, which is flat and cylindrical. Specifically, the exterior member 10 has a pair of opposing bottoms M1 and M2, and a side wall M3 located between bottoms M1 and M2. That is, the side wall M3 connects bottoms M1 and M2 and surrounds the battery element 40. The upper end of the side wall M3 is connected to bottom M1. The lower end of the side wall M3 is connected to bottom M2. The planar shapes of bottoms M1 and M2 are circular. The side wall M3 is a cylindrical member with a circular planar shape.

[0024] Furthermore, the exterior member 10 has a positive terminal plate 11, a negative terminal plate 12, and a cylindrical wall portion 13. The positive terminal plate 11, the negative terminal plate 12, and the cylindrical wall portion 13 are joined to each other, and the internal space of the exterior member 10 is sealed. The positive terminal plate 11 constitutes the bottom portion M1, and the negative terminal The plate 12 constitutes the bottom portion M2, and the cylindrical wall portion 13 constitutes the side wall portion M3.

[0025] The cylindrical wall portion 13 has an internal space that penetrates in the height direction Z. That is, the cylindrical wall portion 13 includes an upper open end 13K1 and a lower open end 13K2 facing each other in the height direction Z. The upper open end 13K1 forms an upper opening that serves as an insertion port through which the battery element 40 can be inserted in the height direction Z. Similarly, the lower open end 13K2 may form a lower opening that serves as an insertion port through which the battery element 40 can be inserted in the height direction Z. The cylindrical wall portion 13 is made of a metal laminate film member having a laminated structure in which a metal foil 131 and a resin film 132 are bonded together.

[0026] As shown in Figures 1A and 1B, the positive terminal plate 11 is a substantially disc-shaped member that closes the upper opening of the cylindrical wall portion 13. The positive terminal plate 11 is joined to the upper open end 13K1 of the cylindrical wall portion 13 without any gaps. The positive terminal plate 11 includes an outer surface 11S1 extending along a horizontal plane perpendicular to the height direction Z, and an end face 11TS that circumfers along the outer edge of the outer surface 11S1. As shown in Figures 1A and 1B, the negative terminal plate 12 is a substantially disc-shaped member that closes the lower opening of the cylindrical wall portion 13. The negative terminal plate 12 is joined to the lower open end 13K2 of the cylindrical wall portion 13 without any gaps. The negative terminal plate 12 includes an outer surface 12S1 extending along a horizontal plane perpendicular to the height direction Z, and an end face 12TS that circumfers along the outer edge of the outer surface 12S1. In this embodiment of the secondary battery, the positive terminal plate 11, the cylindrical wall portion 13, and the negative terminal plate 12 are integrated to form the outer casing member 10. Therefore, the secondary battery of this embodiment has a structure in which the battery element 40 is sealed within the internal space V of the outer casing member 10.

[0027] The positive terminal plate 11 and the negative terminal plate 12 are external connection terminals for connecting to the outside world. The positive terminal plate 11 is connected to the positive electrode 41 (described later) of the battery element 40 via the positive lead 51. The negative terminal plate 12 is connected to the negative electrode 42 (described later) of the battery element 40 via the negative lead 52. Both the positive terminal plate 11 and the negative terminal plate 12 are conductive plate-shaped members made of, for example, a metal material. When using the secondary battery of this embodiment, the positive electrode 41 and the negative electrode 42 are connected to the electronic device via the positive terminal plate 11 and the negative terminal plate 12, respectively. Therefore, the electronic device can operate using the secondary battery as a power source.

[0028] The positive electrode terminal plate 11 contains one or more conductive materials, such as metal materials and alloy materials. Conductive materials include, for example, aluminum and aluminum alloys. The positive electrode terminal plate 11 may also be a clad material formed by rolling and bonding a metal layer made of one or more of the following: Fe (iron), Cu (copper), Ni (nickel), stainless steel, iron alloy, copper alloy, and nickel alloy, to an aluminum layer. More specifically, as the positive electrode terminal plate 11, a composite member having a three-layer structure of, for example, an Al (aluminum) layer, a stainless steel layer, and a nickel layer can be used. In this composite member, the Al layer is located inside the outer casing member 10 (on the internal space V side) and bonded to the positive electrode lead 51, and the nickel layer is arranged to be exposed on the outer surface 11S1 of the positive electrode terminal plate 11. The type of stainless steel is not particularly limited, but specifically, it includes SUS304 and SUS316.

[0029] The negative electrode terminal plate 12 contains one or more conductive materials, such as metallic materials and alloy materials. Examples of conductive materials include Fe (iron), Cu (copper), Ni (nickel), stainless steel, iron alloys, copper alloys, and nickel alloys. The type of stainless steel is not particularly limited, but specifically, examples include SUS304 and SUS316.

[0030] The exterior member 10 may further have an adhesive resin layer 133. The positive terminal plate 11 is joined to the upper open end 13K1 of the cylindrical wall portion 13 via the adhesive resin layer 133. Negative terminal The plate 12 is joined to the lower open end 13K2 of the cylindrical wall portion 13 via an adhesive resin layer 133. More specifically, as shown in Figures 2 and 3, for example, the cylindrical wall portion 13 has an inner wall surface 13S facing the battery element 40. The inner wall surface 13S is covered by the adhesive resin layer 133. Here, the end face 11TS of the positive terminal plate 11 is joined to the inner wall surface 13S via the adhesive resin layer 133. Similarly, the end face 12TS of the negative terminal plate 12 is joined to the inner wall surface 13S near the lower open end 13K2 via the adhesive resin layer 133. With this structure, the positive terminal plate 11 and the metal foil 131 of the cylindrical wall portion 13 are electrically insulated, and the negative terminal plate 12 and the metal foil 131 of the cylindrical wall portion 13 are electrically insulated. Therefore, a short circuit between the positive terminal plate 11 and the negative terminal plate 12 is prevented.

[0031] The adhesive resin layer 133 may be made of a thermoplastic resin such as polypropylene or polyethylene. More specifically, an unoriented polypropylene (CPP) film is preferred. The thickness W133 of the adhesive resin layer 133 (see Figure 3) can be 10 μm or more and 100 μm or less. Preferably, the thickness W133 of the adhesive resin layer 133 is 20 μm or more and 50 μm or less. However, the thickness W133U of the portion of the adhesive resin layer 133 sandwiched in the gap between the positive electrode terminal plate 11 and the metal foil 131, and the thickness W133L of the portion sandwiched in the gap between the negative electrode terminal plate 12 and the metal foil 131, are both thinner than the thickness W133 of the portion excluding both the gap between the positive electrode terminal plate 11 and the metal foil 131 and the gap between the negative electrode terminal plate 12 and the metal foil 131.

[0032] The metal foil 131 constituting the cylindrical wall portion 13 is made of, for example, aluminum or stainless steel. The type of stainless steel is not particularly limited, but specifically, it is SUS304 and SUS316. Other materials that can be used to make up the metal foil 131 include iron, copper, nickel, iron alloys, aluminum alloys, copper alloys, and nickel alloys. The thickness of the positive terminal plate 11 and the negative terminal plate 12 should both be greater than the thickness of the metal foil 131. Furthermore, the rigidity of the positive terminal plate 11 and the rigidity of the negative terminal plate 12 should both be higher than the rigidity of the metal foil 131.

[0033] The resin film 132 can be constructed using polyamide resin or polyethylene terephthalate. It is preferable to use a resin with higher heat resistance than the resin material used for the adhesive resin layer 133.

[0034] [Battery element] The battery element 40 is a power generation element that carries out a charge-discharge reaction and is housed in the internal space V of the outer casing member 10, as shown in Figures 1B and 2. The battery element 40 includes a positive electrode 41 and a negative electrode 42. Here, the battery element 40 further includes a separator 43 and an electrolyte (not shown), which is a liquid electrolyte.

[0035] The center line PC shown in Figure 2 is a line segment corresponding to the center of the battery element 40 in the direction along the outer diameter D of the secondary battery (outer casing member 10). In other words, the position P0 of the center line PC corresponds to the position of the center of the battery element 40.

[0036] The battery element 40 is a so-called electrode winding. That is, in the battery element 40, as shown in Figures 2 and 4, for example, the positive electrode 41 and the negative electrode 42 are stacked radially R apart via a separator 43. The positive electrode 41, the negative electrode 42, and the separator 43 extend along both the winding direction θ and the height direction Z. The radial direction R is the radial direction perpendicular to the height direction Z of the cylindrical wall portion 13 of the outer casing member 10. As shown in Figure 2, the battery element 40 is wound with the stacked positive electrode 41, negative electrode 42, and separator 43 around the center line PC as the winding axis. The positive electrode 41 and the negative electrode 42 are wound while maintaining a state of facing each other via the separator 43. For this reason, a winding center space 40K is formed at the center of the battery element 40. This has been achieved. Figure 4 shows a cross-sectional view of a part of the battery element 40.

[0037] Here, the positive electrode 41, negative electrode 42, and separator 43 are wound such that the separator 43 is positioned at the outermost circumference and innermost circumference of the wound electrode body, respectively. The number of turns for each of the positive electrode 41, negative electrode 42, and separator 43 is not particularly limited and can be set arbitrarily. Also, at the outermost circumference of the battery element 40, the negative electrode 42 is positioned outside the positive electrode 41. That is, the outermost part of the positive electrode 41, which is located on the outermost circumference of the positive electrode 41 included in the battery element 40, is located inside the outermost part of the negative electrode 42, which is located on the outermost circumference of the negative electrode 42 included in the battery element 40. Here, the outermost part of the positive electrode is the outermost one turn of the positive electrode 41 in the battery element 40. The outermost part of the negative electrode is the outermost one turn of the negative electrode 42 in the battery element 40. On the other hand, at the innermost circumference of the battery element 40, it is preferable that the negative electrode 42 is positioned inside the positive electrode 41. In other words, the innermost negative electrode portion of the negative electrode 42 included in the battery element 40 is located inside the innermost positive electrode portion of the positive electrode 41 included in the battery element 40. Here, the innermost positive electrode portion is the innermost one-turn portion of the positive electrode 41 in the battery element 40. The innermost negative electrode portion is the innermost one-turn portion of the negative electrode 42 in the battery element 40.

[0038] The battery element 40 has a three-dimensional shape similar to the three-dimensional shape of the outer casing member 10. Specifically, the battery element 40 has a flattened and substantially cylindrical three-dimensional shape. Compared to the case where the battery element 40 has a three-dimensional shape different from the three-dimensional shape of the outer casing member 10, when the battery element 40 is housed inside the outer casing member 10, so-called dead space, specifically the gap between the outer casing member 10 and the battery element 40, is less likely to occur. As a result, the internal space of the outer casing member 10 is effectively utilized. Consequently, the volume of the element space increases, and the energy density per unit volume of the secondary battery increases.

[0039] (positive electrode) The positive electrode 41 is the first electrode used to carry out the charge-discharge reaction, and as shown in Figure 4, it includes a positive electrode current collector 41A and a positive electrode active material layer 41B.

[0040] The positive electrode current collector 41A has a pair of surfaces on which the positive electrode active material layer 41B is provided. The positive electrode current collector 41A contains a conductive material such as a metal material, and this metal material is such as aluminum.

[0041] The positive electrode active material layer 41B is provided on both sides of the positive electrode current collector 41A and contains one or more types of positive electrode active materials capable of intercalating and deintercalating lithium. However, the positive electrode active material layer 41B may be provided on only one side of the positive electrode current collector 41A. Furthermore, the positive electrode active material layer 41B may also contain a positive electrode binder and a positive electrode conductive agent. The method for forming the positive electrode active material layer 41B is not particularly limited, but specifically, it may be a coating method.

[0042] The positive electrode active material contains a lithium compound. This lithium compound is a general term for compounds that contain lithium as a constituent element, and more specifically, it is a compound that contains lithium along with one or more transition metal elements as constituent elements. This is because a high energy density can be obtained. However, the lithium compound may further contain one or more of any other elements (excluding lithium and transition metal elements). The type of lithium compound is not particularly limited, but specifically, it includes oxides, phosphoric acid compounds, silicate compounds, and borate compounds. Specific examples of oxides include LiNiO2, LiCoO2, and LiMn2O4, and specific examples of phosphoric acid compounds include LiFePO4 and LiMnPO4.

[0043] The positive electrode binder contains one or more of the following: synthetic rubber and polymer compounds. Synthetic rubber is styrene-butadiene rubber, while polymer compounds are polyvinylidene fluoride. The positive electrode conductive agent contains one or more of the following: carbon materials, and carbon materials are graphite, carbon black, acetylene black, and Ketjen black. However, the conductive material may also be a metal material or a polymer compound.

[0044] (Negative electrode) The negative electrode 42 is a second electrode used to advance the charge-discharge reaction, and as shown in Figure 4, it includes a negative electrode current collector 42A and a negative electrode active material layer 42B.

[0045] The negative electrode current collector 42A has a pair of surfaces on which the negative electrode active material layer 42B is provided. The negative electrode current collector 42A contains a conductive material such as a metal material, and this metal material is such as copper.

[0046] The negative electrode active material layer 42B is provided on both sides of the negative electrode current collector 42A and contains one or more types of negative electrode active materials capable of intercalating and deintercalating lithium. However, the negative electrode active material layer 42B may be provided on only one side of the negative electrode current collector 42A. Furthermore, the negative electrode active material layer 42B may also contain a negative electrode binder and a negative electrode conductive agent. Details regarding the negative electrode binder and negative electrode conductive agent are the same as the details regarding the positive electrode binder and positive electrode conductive agent. The method for forming the negative electrode active material layer 42B is not particularly limited, but specifically, it is one or more types from among coating, gas phase, liquid phase, thermal spraying, and firing (sintering).

[0047] The negative electrode active material contains either or both carbon materials and metallic materials because they allow for high energy density. Carbon materials include easily graphitizable carbon, poorly graphitizable carbon, and graphite (natural graphite and artificial graphite). Metallic materials are materials that contain one or more metallic elements and metalloid elements capable of forming alloys with lithium, such as silicon and tin, either or both. However, metallic materials may be elements, alloys, compounds, mixtures of two or more of these, or materials containing two or more phases. Specific examples of metallic materials are TiSi2 and SiO2. x (0 <x≦2、または0.2<x<1.4)などである。

[0048] Here, the height of the negative electrode 42 is greater than the height of the positive electrode 41. That is, as shown in Figure 4, the upper edge 42UT of the negative electrode 42 protrudes above the upper edge 41UT of the positive electrode 41, and the lower edge 42BT of the negative electrode 42 protrudes below the lower edge 41BT of the positive electrode 41. This is to prevent lithium released from the positive electrode 41 from depositing. This "height" is the dimension corresponding to the height H of the secondary battery described above, that is, the vertical dimension (height direction Z) in Figures 1 and 2, respectively. The definition of height explained here will be the same hereafter.

[0049] (Separator) As shown in Figures 2 and 4, the separator 43 is an insulating porous membrane placed between the positive electrode 41 and the negative electrode 42. The separator 43 allows lithium ions to pass through while preventing a short circuit between the positive electrode 41 and the negative electrode 42. The separator 43 contains a polymer compound such as polyethylene.

[0050] Here, as shown in Figure 2, the height of the separator 43 is greater than the height of the negative electrode 42. In other words, the separator 43 should protrude both above and below the negative electrode 42.

[0051] (electrolyte) The electrolyte is impregnated into the positive electrode 41, the negative electrode 42, and the separator 43, and contains a solvent and an electrolyte salt. The solvent contains one or more non-aqueous solvents (organic solvents) such as carbonate ester compounds, carboxylic acid ester compounds, and lactone compounds, and the electrolyte containing such a non-aqueous solvent is a so-called non-aqueous electrolyte. The electrolyte salt contains one or more light metal salts such as lithium salts.

[0052] [Positive lead] The positive lead 51 is housed in the internal space V of the outer casing member 10, as shown in Figure 2. The positive lead 51 is a connecting wire electrically connected to the positive electrode 41 and the positive terminal plate 11, respectively. Therefore, the positive terminal plate 11 (bottom M1) is electrically connected to the positive electrode 41 via the positive lead 51. The secondary battery shown in Figure 2 has one positive lead 51. However, the secondary battery may have two or more positive leads 51.

[0053] The positive lead 51 is connected to the positive current collector 41A so as to protrude upward from the upper end edge 41UT of the positive electrode 41. Also, as shown in Figure 2, the horizontal portion 511 of the positive lead 51 that extends along a horizontal plane perpendicular to the height direction Z is connected to the inner surface 11S2 of the positive terminal plate 11. The method of connecting the positive lead 51 is not particularly limited, but specifically, it is one or more types of welding methods such as resistance welding and laser welding. Details regarding the welding methods described here will also be used hereafter. The positive lead 51 is electrically insulated from the negative terminal plate 12 and the negative electrode 42 of the battery element 40. The horizontal portion 511 of the positive lead 51 is sandwiched between the positive terminal plate 11 and the battery element 40 in the height direction Z.

[0054] In this way, the horizontal portion 511 of the positive electrode lead 51 extends along the inner surface 11S2, which is the lower surface of the positive electrode terminal plate 11, and the upper surface of the battery element 40, respectively, and is sandwiched between the positive electrode terminal plate 11 and the battery element 40. As a result, the horizontal portion 511 of the positive electrode lead 51 is held in place by the positive electrode terminal plate 11 and the battery element 40. Therefore, the positive electrode lead 51 is less likely to move inside the outer casing member 10. Even if the secondary battery is subjected to external forces such as vibration and shock, the positive electrode lead 51 is less likely to move, making it less likely to be damaged. Damage to the positive electrode lead 51 here refers to cracks in the positive electrode lead 51, breakage of the positive electrode lead 51, or detachment of the positive electrode lead 51 from the positive electrode 41.

[0055] The fact that the positive electrode lead 51 is difficult to move inside the outer casing 10 means that the battery element 40 is also difficult to move inside the outer casing 10. Therefore, when the secondary battery is subjected to vibration or shock, it is possible to avoid problems such as unwinding of the battery element 40, which is the electrode winding.

[0056] Furthermore, as shown in Figure 2, an insulating film 62 is placed between the horizontal portion 511 of the positive electrode lead 51 and the upper surface of the battery element 40. This insulates the positive electrode lead 51 from the negative electrode 42 of the battery element 40 via the insulating film 62, preventing a short circuit between the positive electrode lead 51 and the negative electrode 42. Alternatively, the horizontal portion 511 of the positive electrode lead 51 may be covered with an insulating sealant. This is because the positive electrode lead 51 is insulated from the negative electrode 42 via the sealant, preventing a short circuit between the positive electrode lead 51 and the negative electrode 42. The sealant is, for example, an insulating material that covers the periphery of the positive electrode lead 51, and is constructed by attaching two insulating tapes to the front and back surfaces of the positive electrode lead 51, respectively. The sealant contains one or more insulating materials such as insulating polymer compounds, and the insulating material is polyimide, for example.

[0057] Details regarding the forming material of the positive electrode lead 51 are the same as details regarding the forming material of the positive electrode current collector 41A. However, the forming material of the positive electrode lead 51 and the forming material of the positive electrode current collector 41A may be the same or different.

[0058] The connection position of the positive electrode lead 51 to the positive electrode 41 is not particularly limited and can be set arbitrarily. The positive electrode lead 51 is provided separately from the positive electrode current collector 41A. However, since the positive electrode lead 51 is physically continuous with the positive electrode current collector 41A, it may be integrated with the positive electrode current collector 41A.

[0059] [Negative lead] The negative electrode lead 52 is housed in the internal space V of the outer casing member 10, as shown in Figure 2. The negative electrode lead 52 is a connecting wire electrically connected to the negative electrode 42 and the negative electrode terminal plate 12, respectively. Therefore, the negative electrode terminal plate 12 (bottom M2) is electrically connected to the negative electrode 42 via the negative electrode lead 52. The secondary battery shown in Figure 2 has one negative electrode lead 52. However, the secondary battery may have two or more negative electrode leads 52.

[0060] As previously mentioned, the negative electrode lead 52 is connected to the negative electrode current collector 42A so as to protrude downward from the lower end edge 42BT of the negative electrode 42. Furthermore, as shown in Figure 2, the horizontal portion 521 of the negative electrode lead 52 that extends along a horizontal plane perpendicular to the height direction Z is connected to the inner surface 12S2 of the negative electrode terminal plate 12. The method of connecting the negative electrode lead 52 is not particularly limited, but specifically, it is one or more types of welding methods such as resistance welding and laser welding.

[0061] The negative lead 52 is electrically insulated from the positive terminal plate 11 and the positive electrode 41 of the battery element 40. The horizontal portion 521 of the negative lead 52 is sandwiched between the negative terminal plate 12 and the battery element 40 in the height direction Z.

[0062] In this way, the horizontal portion 521 of the negative electrode lead 52 extends along the inner surface 12S2, which is the upper surface of the negative electrode terminal plate 12, and the lower surface of the battery element 40, and is sandwiched between the negative electrode terminal plate 12 and the battery element 40. As a result, the horizontal portion 521 of the negative electrode lead 52 is held in place by the negative electrode terminal plate 12 and the battery element 40. Therefore, the negative electrode lead 52 is less likely to move inside the outer casing member 10. Even if the secondary battery is subjected to external forces such as vibration and shock, the negative electrode lead 52 is less likely to move, making it less likely to be damaged. Damage to the negative electrode lead 52 here refers to cracks in the negative electrode lead 52, the negative electrode lead 52 being cut, or the negative electrode lead 52 being detached from the negative electrode 42.

[0063] The fact that the negative electrode lead 52 is difficult to move inside the outer casing 10 means that the battery element 40 is also difficult to move inside the outer casing 10. Therefore, when the secondary battery is subjected to vibration or shock, it is possible to avoid problems such as unraveling of the battery element 40, which is the electrode winding.

[0064] Furthermore, as shown in Figure 2, an insulating film 63 is placed between the horizontal portion 521 of the negative electrode lead 52 and the lower surface of the battery element 40. This insulates the negative electrode lead 52 from the positive electrode 41 of the battery element 40 via the insulating film 63, preventing a short circuit between the negative electrode lead 52 and the positive electrode 41. Alternatively, the horizontal portion 521 of the negative electrode lead 52 may be covered with an insulating sealant. This is because the negative electrode lead 52 is insulated from the positive electrode 41 via the sealant, preventing a short circuit between the negative electrode lead 52 and the positive electrode 41.

[0065] Details regarding the material for forming the negative electrode lead 52 are the same as those regarding the material for forming the negative electrode current collector 42A. However, the material for forming the negative electrode lead 52 and the material for forming the negative electrode current collector 42A may be the same or different. Nickel is an example of a constituent material for the negative electrode lead 52.

[0066] The connection position of the negative electrode lead 52 to the negative electrode 42 is not particularly limited and can be set arbitrarily. Here, the negative electrode lead 52 is connected to the outermost part of the negative electrode 42 that constitutes the battery element 40, which is an electrode winding body.

[0067] The negative electrode lead 52 is provided separately from the negative electrode current collector 42A. However, since the negative electrode lead 52 is physically continuous with the negative electrode current collector 42A, it may be integrated with the negative electrode current collector 42A.

[0068] [Insulating film] As shown in Figure 2, the insulating film 62 is an insulating member positioned between the positive electrode lead 51 and the battery element 40 in the height direction Z. Here, the insulating film 62 has a ring-shaped planar form with an opening at a location corresponding to the winding center space 40K in the height direction Z. The insulating film 62 may contain one or more types of insulating materials such as insulating polymer compounds. The insulating material contained in the insulating film 62 is polyimide, for example.

[0069] As shown in Figure 2, the insulating film 63 is an insulating member positioned between the negative electrode lead 52 and the battery element 40 in the height direction Z. Here, the insulating film 63 has a ring-shaped planar form with an opening at a location corresponding to the winding center space 40K in the height direction Z. Details regarding the material forming the insulating film 63 are the same as those regarding the material forming the insulating film 62. However, the material forming the insulating film 63 and the material forming the insulating film 62 may be the same or different from each other.

[0070] [others] Furthermore, the secondary battery may also include one or more other components. Specifically, the secondary battery is equipped with a safety valve mechanism. This safety valve mechanism disconnects the electrical connection between the outer casing member 10 and the battery element 40 when the internal pressure of the outer casing member 10 reaches a certain level. The causes of the internal pressure of the outer casing member 10 reaching a certain level include a short circuit occurring inside the secondary battery and the secondary battery being heated from the outside. The location of the safety valve mechanism is not particularly limited, but it is preferable that the safety valve mechanism be provided at either the bottom M1 or M2.

[0071] Furthermore, the secondary battery may have an insulator other than the insulating films 62 and 63 between the outer casing 10 and the battery element 40. This insulator includes one or more types of insulating films and insulating sheets, etc., and prevents short circuits between the outer casing 10 and the battery element 40. The installation range of the insulator is not particularly limited and can be set arbitrarily.

[0072] Furthermore, the exterior member 10 is provided with an opening valve. This opening valve opens when the internal pressure of the exterior member 10 reaches a certain level, thereby releasing the internal pressure. The location of the opening valve is not particularly limited, but among them, the bottom part M1 or M2 is preferred, and the bottom part M2 is more preferred, similar to the location of the safety valve mechanism described above.

[0073] (1-2.Operation) During charging of the secondary battery, lithium is released from the positive electrode 41 in the battery element 40, and this lithium is absorbed into the negative electrode 42 via the electrolyte. Conversely, during discharging of the secondary battery, lithium is released from the negative electrode 42 in the battery element 40, and this lithium is absorbed into the positive electrode 41 via the electrolyte. During these charging and discharging processes, lithium is absorbed and released in an ionic state.

[0074] (1-3. Manufacturing method) Next, the manufacturing method of the secondary battery of this embodiment will be described. The following description will refer to Figures 1A to 4.

[0075] Here, in order to form the exterior member 10, a positive terminal plate 11, a cylindrical wall portion 13, and a negative terminal plate 12 are prepared, which are physically separated from each other, as shown in Figure 1B. Next, for example, with the end face 12TS of the negative terminal plate 12 in contact with the lower open end 13K2 of the cylindrical wall portion 13, the end face 12TS is bonded to the lower open end 13K2 by heating and pressurizing the contact point.

[0076] [Fabrication of the positive electrode] First, a positive electrode mixture is prepared by mixing positive electrode active material, positive electrode binder, and positive electrode conductive agent. Next, a paste-like positive electrode mixture slurry is prepared by adding the prepared positive electrode mixture to an organic solvent. Subsequently, the positive electrode mixture slurry is applied to both sides of the positive electrode current collector 41A to form a positive electrode active material layer 41B. Finally, the positive electrode active material layer 41B is compressed and molded using a roll press or the like. In this case, the positive electrode active material layer 41B may be heated, or the compression molding may be repeated multiple times. This produces the positive electrode 41.

[0077] [Fabrication of the negative electrode] The negative electrode 42 is manufactured using the same procedure as that used for manufacturing the positive electrode 41. Specifically, a negative electrode mixture, which consists of a negative electrode active material, a negative electrode binder, and a negative electrode conductive agent, is added to an organic solvent to prepare a paste-like negative electrode mixture slurry. Then, the negative electrode mixture slurry is applied to both sides of the negative electrode current collector 42A to form a negative electrode active material layer 42B. After this, the negative electrode active material layer 42B is compressed and molded using a roll press or the like. This completes the manufacturing of the negative electrode 42.

[0078] [Preparation of electrolyte solution] The electrolyte salt is added to the solvent. This disperses or dissolves the electrolyte salt in the solvent, thus preparing the electrolyte solution.

[0079] [Assembly of rechargeable batteries] First, using a welding method such as resistance welding, the positive lead 51 is connected to the positive electrode 41 (positive electrode current collector 41A), and the negative lead 52 is connected to the negative electrode 42 (negative electrode current collector 42A).

[0080] Next, the positive electrode 41 and the negative electrode 42 are stacked with a separator 43 in between, and then a wound body is produced by winding the stacked material including the positive electrode 41, the negative electrode 42, and the separator 43. This wound body has the same configuration as the battery element 40, except that the positive electrode 41, the negative electrode 42, and the separator 43 are not impregnated with electrolyte.

[0081] Next, the insulating film 63 and the wound bodies to which the positive lead 51 and negative lead 52 are connected are housed inside the cylindrical wall portion 13 through the upper opening of the cylindrical wall portion 13. At this time, the negative lead 52 is connected to the negative terminal plate 12 using a welding method such as resistance welding. Subsequently, the insulating film 62 is placed on top of the wound bodies.

[0082] Next, the positive lead 51 is connected to the positive terminal plate 11 using a welding method such as resistance welding.

[0083] Next, electrolyte is injected into the cylindrical wall portion 13 through the upper opening. This impregnates the wound body, which includes the positive electrode 41, the negative electrode 42, and the separator 43, with the electrolyte, thereby fabricating the battery element 40, which is an electrode wound body.

[0084] Next, the upper opening is closed with the positive terminal plate 11, and with the end face 11TS of the positive terminal plate 11 in contact with the upper open end 13K1 of the cylindrical wall portion 13, heating and pressurizing are applied to the contact point to bond the end face 11TS to the upper open end 13K1. This forms the exterior member 10, and the battery elements 40 and the like are housed in the internal space V of the exterior member 10, completing the assembly of the secondary battery.

[0085] [Stabilization of secondary batteries] The assembled secondary battery is then charged and discharged. Various conditions, such as ambient temperature, number of charge / discharge cycles, and charge / discharge conditions, can be set arbitrarily. This causes a coating to form on the surface of the negative electrode 42, etc., thereby electrochemically stabilizing the state of the secondary battery. Thus, the secondary battery is completed.

[0086] (1-4. Action and Effects) As described above, in the secondary battery of this embodiment, the exterior member 10 that houses the battery element 40 has a cylindrical wall portion 13 having a laminated structure of metal foil 131 and resin film 132, a positive electrode terminal plate 11 joined to the upper open end 13K1 of the cylindrical wall portion 13, and a negative electrode terminal plate 12 joined to the lower open end 13K2 of the cylindrical wall portion 13. Therefore, compared to the case in which an exterior member made of a metal can is used, for example, the dimensions of the exterior member 10 can be reduced without reducing the size of the battery element 40. Specifically, by constructing the cylindrical wall portion 13, which has a shape with higher mechanical strength compared to the positive electrode terminal plate 11 and the negative electrode terminal plate 12, from a metal laminate film member, it is possible to make it thinner, lighter, and smaller. On the other hand, by constructing the positive electrode terminal plate 11 and the negative electrode terminal plate 12 from a rigid metal plate-shaped member, the overall mechanical strength of the exterior member 10 is improved, and the shape of the cylindrical wall portion 13 and the exterior member 10 can be maintained even when external force is applied.

[0087] Therefore, according to the secondary battery of this embodiment, the size of the battery element 40 can be maintained while the outer casing member 10 can be made thinner, lighter, and smaller. Thus, the secondary battery of this embodiment can achieve high capacity despite its compact configuration. Furthermore, the secondary battery of this embodiment, having the above configuration, has excellent sealing properties despite its simple structure, and can prevent electrolyte leakage. Moreover, it can avoid problems such as damage to the positive electrode lead 51, damage to the negative electrode lead 52, and short circuits between the positive electrode 41 and the negative electrode 42. Thus, the secondary battery of this embodiment also has high reliability. In contrast, for example, in the case of a secondary battery in which the entire outer casing member is made of metal laminate film material, the mechanical strength is low and the reliability is inferior. Moreover, since the positive electrode terminal and the negative electrode terminal need to be taken out from the gap at the bonding location of the metal laminate film material, this results in a decrease in volume efficiency.

[0088] In particular, in the secondary battery of this embodiment, since the outer surface 11S1 and the inner surface 11S2 are flat surfaces perpendicular to the height direction Z, the ratio of the volume of the battery element 40 to the volume of the outer casing member 10 can be increased, and a higher capacity efficiency can be obtained. Also, in the secondary battery of this embodiment, since the inner surface 11S2 and the inner surface 12S2 are flat surfaces perpendicular to the height direction Z, the battery element 40 can occupy the internal space V of the outer casing member 10 without waste. Therefore, a higher capacity efficiency can be obtained.

[0089] Furthermore, in the secondary battery of this embodiment, since the outer shape of the outer casing member 10 is cylindrical, it can have higher mechanical strength compared to, for example, when the outer casing member has a rectangular prism shape or an elliptical shape. However, the secondary battery of this disclosure also includes cases where the outer casing member has a rectangular prism shape or an elliptical shape.

[0090] Furthermore, if the secondary battery is a lithium-ion secondary battery, sufficient battery capacity can be stably obtained by utilizing the intercalation and deintercalation of lithium.

[0091] <2. Modified Examples of One Embodiment> (First variation) Next, with reference to Figure 5, an exterior member 10A as a first modified example of one embodiment of the present disclosure will be described. Figure 5 is an enlarged cross-sectional view of a part of the exterior member 10A as the first modified example, and corresponds to Figure 3, which shows an enlarged view of a part of the exterior member 10 of the above embodiment. In the exterior member 10 of the above embodiment, the entire inner wall surface 13S of the cylindrical wall portion 13 is covered with an adhesive resin layer 133. In contrast, in the exterior member 10A of the first modified example, instead of the adhesive resin layer 133, an adhesive resin layer 14 is provided in the gap between the end face 11TS of the positive terminal plate 11 and the inner wall surface 13S, and in the gap between the end face 12TS of the negative terminal plate 12 and the inner wall surface 13S, respectively. Except for this point, the configuration of the exterior member 10A of the first modified example is substantially the same as the configuration of the exterior member 10 of the above embodiment. Note that the adhesive resin layer 14 can be made of the same material as the adhesive resin layer 133. A secondary battery equipped with the exterior member 10A of the first modified example can be expected to have the same effects as a secondary battery equipped with the exterior member 10 of the above embodiment.

[0092] (Second variation) Next, with reference to Figure 6, an exterior member 10B as a second modification of one embodiment of the present disclosure will be described. Figure 6 is an enlarged cross-sectional view of a part of the exterior member 10B as the second modification, and corresponds to Figure 3, which shows an enlarged view of a part of the exterior member 10 of the first embodiment. In the exterior member 10B of the second modification, a projection 111 is provided on the outer edge of the positive terminal plate 11 that protrudes toward the negative terminal plate 12, and a projection 121 is provided on the outer edge of the negative terminal plate 12 that protrudes toward the positive terminal plate 11. In addition, in the exterior member 10B, an adhesive resin layer 14 is provided in the gap between the upper end surface 13US of the cylindrical wall portion 13 and the positive terminal plate 11, and in the gap between the lower end surface 13LS of the cylindrical wall portion 13 and the negative terminal plate 12. Except for these points, the configuration of the exterior member 10B of the second modification is substantially the same as the configuration of the exterior member 10 of the first embodiment. The same effects as those of the secondary battery equipped with the exterior member 10 of the first embodiment can be expected in a secondary battery equipped with the exterior member 10 of the first embodiment.

[0093] (Third variation) Next, with reference to Figure 7, an exterior member 10C as a third modification of one embodiment of the present disclosure will be described. Figure 7 is an enlarged cross-sectional view of a part of the exterior member 10C as the third modification, and corresponds to Figure 3, which shows an enlarged view of a part of the exterior member 10 of the first embodiment. In the exterior member 10C of the third modification, a projection 111 is provided on the outer edge of the positive terminal plate 11 that protrudes toward the negative terminal plate 12, and a projection 121 is provided on the outer edge of the negative terminal plate 12 that protrudes toward the positive terminal plate 11. Except for these points, the configuration of the exterior member 10C of the third modification is substantially the same as the configuration of the exterior member 10 of the first embodiment. A secondary battery equipped with the exterior member 10C of the third modification has higher mechanical strength than a secondary battery equipped with the exterior member 10 of the first embodiment.

[0094] (Fourth variation) Next, with reference to Figure 8, an exterior member 10D as a fourth modification of one embodiment of the present disclosure will be described. Figure 8 is a cross-sectional view showing the schematic configuration of the exterior member 10D as the fourth modification, and corresponds to Figure 2, which represents the exterior member 10 of the above embodiment. In the exterior member 10D of the fourth modification, the inner surface 11S2 of the positive terminal plate 11 and the inner surface 12S2 of the negative terminal plate 12 are curved surfaces that are convex toward the outside of the exterior member 10D. Except for these points, the configuration of the exterior member 10D of the fourth modification is substantially the same as the configuration of the exterior member 10 of the above embodiment. A secondary battery equipped with the exterior member 10D of the fourth modification has higher mechanical strength than a secondary battery equipped with the exterior member 10 of the above embodiment.

[0095] Although the present technology has been described above with reference to one embodiment and several modifications, the configuration of the present technology is not limited to the configuration described in one embodiment and several modifications, and can be modified in various ways.

[0096] Specifically, the outer shape of the exterior component is cylindrical, but this disclosure is not limited to this. For example, a secondary battery may have an exterior component having a prismatic or elliptical shape. In the case of a prismatic exterior component, the corners may be rounded.

[0097] Furthermore, while the above embodiment of the secondary battery illustrates a case where both the outer surface of the first electrode terminal plate and the outer surface of the second electrode terminal plate of the exterior member are flat surfaces, this disclosure is not limited thereto. For example, at least one of the outer surface of the first electrode terminal plate and the outer surface of the second electrode terminal plate may include recesses or protrusions.

[0098] Furthermore, while we have described the case where the electrode reactant is lithium, the electrode reactant is not particularly limited. Therefore, as mentioned above, the electrode reactant may be other alkali metals such as sodium and potassium, or alkaline earth metals such as beryllium, magnesium, and calcium. In addition, the electrode reactant may be other light metals such as aluminum.

[0099] The effects described herein are illustrative only, and the effects of this disclosure are not limited to those described herein. Therefore, other effects may be obtained with respect to this disclosure.

[0100] Furthermore, this disclosure may take the following forms: <1> A battery element having a first electrode and a second electrode, An outer casing member housing the aforementioned battery element and Equipped with, The exterior member is, A cylindrical wall portion having a laminated structure of metal foil and resin film, including a first open end and a second open end facing each other in a first direction, A first electrode terminal plate joined to the first open end of the cylindrical wall portion, The second electrode terminal plate is joined to the second open end of the cylindrical wall portion. has Secondary battery. <2> The exterior member further comprises an adhesive resin layer, The first electrode terminal plate is joined to the first open end of the cylindrical wall portion via the adhesive resin layer. The second electrode terminal plate is joined to the second open end of the cylindrical wall portion via the adhesive resin layer. the above <1> The rechargeable battery described. <3> The cylindrical wall portion has an inner wall surface facing the battery element, The aforementioned inner wall surface is covered with an adhesive resin layer. The first electrode terminal plate extends along a first plane perpendicular to the first direction and includes a first end face. The second electrode terminal plate extends along the first surface and includes a second end surface. The first end face is joined to the inner wall surface via the adhesive resin layer, The second end face is joined to the inner wall surface via the adhesive resin layer. the above <1> or <2> The rechargeable battery described. <4> Each of the first electrode terminal plate and the second electrode terminal plate is made of a metallic material. the above <1> from <3> A rechargeable battery as described in one of the following. <5> The thickness of both the first electrode terminal plate and the second electrode terminal plate is greater than the thickness of the metal foil. the above <1> from <4> A rechargeable battery as described in one of the following. <6> The rigidity of both the first electrode terminal plate and the second electrode terminal plate is higher than the rigidity of the metal foil. the above <1> from <5> A rechargeable battery as described in one of the following. [Explanation of symbols]

[0101] 10...Exterior component, M1, M2...Bottom, M3...Side wall, 11...Positive terminal plate, 11S1...Outer surface, 11S2...Inner surface, 11TS...End face, 12...Negative terminal plate, 12S1...Outer surface, 12S2...Inner surface, 12TS...End face, 13...Cylindrical wall, 13K1...Upper open end, 13K2...Lower open end, 13S...Inner wall surface, 131...Metal foil, 132...Resin film, 133...Adhesive resin layer, 40...Battery element, 41...Positive electrode, 41A...Positive electrode current collector, 41B...Positive electrode active material layer, 42...Negative electrode, 42A...Negative electrode current collector, 42B...Negative electrode active material layer, 51...Positive electrode lead, 52...Negative electrode lead, 62, 63...Insulating film, PC...Center line, V...Internal space.

Claims

1. A battery element having a first electrode and a second electrode, An outer casing member housing the aforementioned battery element and Equipped with, The exterior member is, A cylindrical wall portion having a laminated structure in which an adhesive resin layer, a metal foil, and a resin film are laminated in this order from the inside out, including a first open end, The first electrode terminal plate, which is joined to the adhesive resin layer at the first open end of the cylindrical wall portion, It has, The thickness of the first portion of the adhesive resin layer sandwiched between the first electrode terminal plate and the metal foil is thinner than the thickness of the third portion of the adhesive resin layer excluding the first portion. Secondary battery.

2. The device further comprises a first lead connecting the first electrode and the first electrode terminal plate, The first lead has a horizontal portion extending along a first plane perpendicular to the first direction, The horizontal portion is sandwiched between the first electrode terminal plate and the battery element in the first direction. The secondary battery according to claim 1.

3. The metal foil has an inner wall surface facing the battery element, The inner wall surface is covered by the adhesive resin layer. The first electrode terminal plate extends along a first plane perpendicular to the first direction and includes a first end face. The first end face is joined to the inner wall surface via the adhesive resin layer. The secondary battery according to claim 1.

4. The first electrode terminal plate has a first projection, The first projection includes the first end face which is joined to the inner wall surface via the adhesive resin layer. The secondary battery according to claim 3.

5. The first electrode terminal plate is made of a metal material. A secondary battery according to any one of claims 1 to 4.

6. The thickness of the first electrode terminal plate is greater than the thickness of the metal foil. A secondary battery according to any one of claims 1 to 4.

7. The rigidity of the first electrode terminal plate is higher than that of the metal foil. A secondary battery according to any one of claims 1 to 4.

8. The horizontal portion is welded to the inner surface of the first electrode terminal plate. The secondary battery according to claim 2.

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